A printed circuit board (PCB) mechanically supports and electrically connects electronic components using conductive tracks, pads and other features etched from copper sheets laminated onto a non-conductive substrate. PCBs can be single sided (one copper layer), double sided (two copper layers) or multi-layer. Conductor on different layers are connected with plated-through holes called vias. Advanced PCBs may contain components - capacitors, resistors or active devices - embedded in the substrate.
Introduction
Multilayer circuit boards at least three conductive layer, two layer surface, and the rest of the layer were synthesized in insulation board. The electrical connection between them is usually through cross circuit board plated through hole. Until further instructions, multilayer printed circuit board and double panel, usually plated through hole plate. In a single panel, even double panel, due to the cross limited number can be realized, these requirements cant get a satisfactory answer. In the case of a large number of interconnection and cross demand, circuit board to achieve a satisfactory performance, it must be expanded to more than two layer board layer, thus appeared the multilayer circuit board.
Multilayer circuit board easy to distinguish
Circuit board according to decide how much of the wiring process difficulty and machining price, ordinary circuit board with single line and double line, commonly known as the single panel and double panel, high-end electronic products, however, because of product space design factors, in addition to the surface wiring, internal stack multilayer circuit, the process of production, made each layer after line, again through the optical device positioning, pressing, let the superposition of multi-layer circuit in a piece of circuit board. Also known as multilayer circuit board. All is greater than or equal to 2 layer PCB, can be called the multilayer circuit board. Multilayer circuit board and can be divided into, multi-layer rigid circuit board, multilayer circuit board, hard and soft layers of hard and soft combination of circuit board.
Multiwire is a patented technique of interconnection which uses machine-routed insulated wires embedded in a non-conducting matrix (often plastic resin). It was used during the 1980s and 1990s. (Kollmorgen Technologies Corp, U.S. Patent 4,175,816 filed 1978) Multiwire is still available in 2010 through Hitachi. There are other competitive discrete wiring technologies that have been developed (Jumatech [2], layered sheets).
Since it was quite easy to stack interconnections (wires) inside the embedding matrix, the approach allowed designers to forget completely about the routing of wires (usually a time-consuming operation of PCB design): Anywhere the designer needs a connection, the machine will draw a wire in straight line from one location/pin to another. This led to very short design times (no complex algorithms to use even for high density designs) as well as reduced crosstalk (which is worse when wires run parallel to each otherwhich almost never happens in Multiwire), though the cost is too high to compete with cheaper PCB technologies when large quantities are needed.
The birth of multilayer circuit board
Due to the increase in density of integrated circuit packaging, led to interconnect highly concentrated, this makes more substrate using a necessity. In the layout of printed circuit boards, the design of unforeseen problems, such as noise, stray capacitance, crosstalk. Printed circuit board design, therefore, must be committed to make the minimum line length and avoid parallel routes, etc. Clearly, in a single panel, even double panel, due to the cross limited number can be realized, these requirements cant get a satisfactory answer. In the case of a large number of interconnection and cross demand, circuit board to achieve a satisfactory performance, it must be expanded to more than two layer board layer, thus appeared the multilayer circuit board. Therefore making multilayer circuit board is designed for complex and/or electronic circuits that are sensitive to noise to choose the appropriate path of wiring to provide more degrees of freedom. Multilayer circuit boards at least three conductive layer, two layer surface, and the rest of the layer were synthesized in insulation board. The electrical connection between them is usually through cross circuit board plated through hole. Until further instructions, multilayer printed circuit board and double panel, usually plated through hole plate.
More substrate is stacked together two or more circuit manufacturing, and reliably predefined mutual connection between them. Because before all the layers of crushed together, has completed the drilling and plating, this technology from the start, in violation of the traditional production process. The two layers inside is composed of traditional double panel, the outer is different, they are composed of independent single panel. Before crushing, the substrate will be drilling, hole plating, graphic transfer, development and etching. By drilling of outer layer is a signal, it is through the hole on the inside edge to form a balanced copper ring be plated through such a way. Then each layer of roller compacted together to form more substrate, the substrate the wave crest welding can be used for more () between the components connected to each other.
RCC may be in a hydraulic press or done in the middle of super pressure tank (autoclave). In hydraulic press, the prepared material (used in pressure stack) is placed in cold or warm up under the pressure of the (high glass transition temperature of the material in the temperature of the 170-180 ). Glass transition temperature is amorphous polymers (resin), or part of the crystalline polymer amorphous region from quite a hard, brittle state changes into a viscous, rubber state temperature.
Substrate is put into use in electronic equipment (computer, military equipment), especially in the case of weight and volume overload. However, this can only be use more substrate cost increase in exchange for a space
And reduce weight. In high speed circuit, the substrate is also useful, they can provide the PCB designer with more than two layers of the plate to lay wires, and provide greater grounding and power supply area.
Multilayer PCB design method
Before designing multilayer PCB, designers need to first according to the size of the circuit, the size of the circuit board, and the requirements of electromagnetic compatibility (EMC) to determine the structure of circuit board, which is decided to adopt 4 layer and 6 layer, or the number of multilayer circuit board. Determine the layer, and then determine how electricity layer and placed within different signal on the layer distribution. This is the problem of multi-layer PCB cascade structure choice. Cascade structure is an important factor affecting PCB EMC performance, is also an important means to restrain electromagnetic interference. This section will introduce multi-layer PCB cascade structure related content.
1.1. The number of layers and superposition principle
Determine the cascade structure of multilayer PCB need to consider more factors. In wiring ways, layer number of the more the wiring, but plate cost and difficulty also increases. For manufacturers, cascade structure symmetry or not is the focus of the need to pay attention to when PCB manufacturing, so the layer number of choice need to consider all aspects of the demand, in order to achieve the best balance.
For experienced designers, after fulfilling the components of the preliminary layout, bottlenecks for PCB wiring place emphasis on analysis. Combined with other EDA tools to analyze circuit board wiring density; Then integrated signal such as difference lines with special wiring requirements, such as sensitive signal lines to the number and variety of determine the signal of the layer number; Then according to the requirement of the power supply, isolation, and the kinds of anti-interference to determine the number of electric layer within. In this way, the whole circuit board layer number is basic assurance.
Determine the circuit board after the number of layers, the next job is reasonably arranged each layer placed the order of the circuit. In this step, the main factors to consider are the following two points.
(1) special signal layer distribution.
(2) power supply layer and the distribution of the strata.
If PCB layers, the more special signal layer, formation and the power of the more the kinds of permutation and combination, how to determine which combination is the optimal and the more difficult, but the general rule has the following several.
(1) signal should layer and an inner electrode layer adjacent power/ground (interior), using the electrical layer of copper film for signal provide shielding.
(2) the internal power supply should be tight coupling between layer and formation, that is, between the internal power supply layer and formation of medium thickness should take smaller values, in order to improve the power supply layer and formation, the capacitance between the resonant frequency. Internal power supply Layer and formation between the medium thickness in Protel Layer Stack Manager (set in the Layer Stack Manager). Select [Design] / [the Layer Stack Manager..." Command, the system pop-up the layer stack manager dialog box, use the mouse to double-click the Prepreg text, pop-up dialog box shown in figure 11-1, can be in the dialog box change the Thickness of insulation layer Thickness of options.
Figure 11-1 set insulation layer thickness
If the potential difference between the power and ground is not big, can use smaller thickness of insulating layer, such as 5 mil (0.127 mm).
(3) circuit of the high speed signals transmission layer should be the middle tier, and sandwiched between two electrode layer in between. Within these two electric layer of copper film can provide electromagnetic shielding for high speed signal transmission, but also can effectively limit the radiation of high-speed signal within two electricity between layers, no foreign interference.
(4) avoid direct adjacent two signal layers. Easy introduction of crosstalk between adjacent signal layer, resulting in circuit function failure. In between the two signals to join the plane can effectively avoid the crosstalk.
(5) multiple grounding electrode layer can effectively reduce the grounding impedance. For example, A signal layer and B signals using separate ground plane, can effectively reduce the common mode interference.
(6) symmetry of layer structure of give attention to two or morethings.
1.2 the cascade structure commonly used
Through the example of 4 layer board below will show how the optimization way of permutation and combination of various kinds of cascade structure.
For the commonly used 4 layer board, there are several cascade mode (from top to bottom).
(1) Siganl_1 (Top), GND (Inner_1), POWER (Inner_2), Siganl_2 (Bottom).
(2) Siganl_1 (Top), POWER (Inner_1), GND (Inner_2), Siganl_2 (Bottom).
(3) POWER (Top), Siganl_1 (Inner_1), GND (Inner_2), Siganl_2 (Bottom).
Obviously, plan 3 power supply layer and formation, lack of effective coupling should not be used.
Then plan 1 and 2 should be how to choose? Under normal circumstances, the designers will choose solution 1 as the structure of the 4 layer board. Reason not scheme 2 shall not be used, but the general PCB are placed at the top level components only, so the plan 1 is relatively appropriate. But when need to be placed on the top floor and the underlying components, and internal power formation between the layer and the thickness is bigger, poor coupling, you need to consider which layer arranged less signal lines. For solution 1, the bottom line is less, can be used in a large area of copper film layer with POWER coupling; On the other hand, if the components main arrangement in the bottom, you should choose to plan 2 plate.
If using the cascade structure as shown in figure 1-1, the power supply layer and ground layer itself has coupling, considering the requirement of the symmetry, generally USES plan 1.
After complete the 4 layer board of cascade structure analysis, the following 6 layer board through a combination of examples to illustrate the permutation and combination of 6 layer board cascade structure mode and optimizing method.
(1) Siganl_1 (Top), GND (Inner_1), Siganl_2 (Inner_2), Siganl_3 (Inner_3), POWER (In).
Scheme adopted 4 signal layer 1 and layer 2 internal power/ground plane, with more signal layer, is advantageous to the wiring between components work, but the defects of the scheme is also evident, characterized by the following two aspects.
1) power supply layer and ground layer separate far away, not fully coupling.
2) signal layer Siganl_2 (Inner_2) and Siganl_3 (Inner_3) directly adjacent to the signal isolation is not good, prone to crosstalk.
(2) Siganl_1 (Top), Siganl_2 (Inner_1), POWER (Inner_2), GND (Inner_3), Siganl_3 (In).
Plan 1, 2 relative to the power supply layer and ground layer with fully coupled, than those of plan 1 has a certain advantage, but Siganl_1 (Top) and Siganl_2 (Inner_1) and Siganl_3 (Inner_4) and Siganl_4 (Bottom) layer directly adjacent signal, signal isolation is not good, easy to occur the crosstalk problem is not solved.
(3) Siganl_1 (Top), GND (Inner_1), Siganl_2 (Inner_2), POWER (Inner_3), GND (Inner_).
Relative to the plan 1 and 2, the solution to reduce a signal layer 3, more an inner layer, although for wiring level decreased, but the scheme solves the scheme 1 and scheme 2 common defects.
1) power supply layer and ground layer tightly coupled.
Within each signal layer
2) with electric layer adjacent directly, and other signal layer are the effective isolation, crosstalk is not easy to happen.
3) Siganl_2 GND (Inner_2) and two electric layer (Inner_1) and POWER (Inner_3) adjacent, can be used to transmit signals at a high speed. Two electrical layer can effectively block outside of Siganl_2 (Inner_2) layer interference and Siganl_2 (Inner_2) to outside interference.
Synthesis of 3 aspects, obviously is a kind of optimization, at the same time, the scheme of 3 and 6 layer board commonly used cascade structure.
Through the analysis of the above two examples, believe that the reader has to have a certain understanding of cascade structure, but in some cases, a single solution can not meet the requirements of all, it is need to consider the design principle of priority issues. Unfortunately due to the PCB board layer is closely related to the design and the characteristics of the actual circuit, anti-jamming performance and the design emphasis of the different circuit is different, so in fact did not determine the priority of these principles is available for reference. But what is clear is that design principle 2 (internal power between layer and formation should be tightly coupled) need to first met when the design, in addition if need high-speed transmission signal in the circuit, then the design principle of 3 (circuit of high speed signals transmission layer should be the middle layer, and between electricity within two layer) must be satisfied. A multilayer laminated structure is presented in table 1-1 reference solution, for readers reference.
2.1 general principles of the components layout
Designers need to follow the general principle in the process of printed circuit board layout are as follows.
(1) components single best placed. If need double placed components, placed in the Bottom Layer (Bottom) pin type components, it is possible to cause the circuit board is not easy to put, is unfavorable to welding, so in the underlying Layer (Bottom) only best placed SMT components, similar to common computer graphics components on the PCB layout method. Only when the single placed on the circuit board of a do silk screen layer, easy to reduce costs.
(2) the reasonable arrangement of the position of the interface components and direction. In general, as a circuit board and the outside world (power supply, signal lines) connection of the connector components, often at the edge of the circuit board, such as serial port and parallel port. If placed in the middle of the circuit board, apparently for wiring, may also be unable to connect with other components of the block. Also should pay attention to the direction of the interface, when placed interface allows the cable to successfully lead, away from the circuit board. Interface place after the completion, should use String interface components (String) clearly indicate the type of the interface; For class interface power supply shall be marked voltage grade, prevent caused by wrong wiring circuit board burned.
(3) high pressure components and low voltage components should have wide electrical isolation belt between the best. That is to say, dont put the difference in voltage grade components together, for electrical insulation already so, also has great benefits for the signal isolation and anti-interference.
(4) that is close to the electrical connection components best placed together. This is the layout of the modular thought.
(5) for the components of the noise, the clock generator and vibration, high frequency components, for example, when placed should try to place them near the CPU clock input. Large current circuit and switch circuit is easy to generate noise, in the layout of these components or modules should be far away from the logic control circuit and storage circuit of high-speed signal circuit, if possible, try to adopt the way of control board combined with the power board, using the interface to connect to, in order to improve the anti-interference ability and the work reliability of circuit board as a whole.
(6) around the power and chip try to place the filter capacitor and decoupling capacitor. Decoupling capacitors and filtering capacitance circuit board layout is to improve the power quality, an important measure to improve anti-interference ability. In practice, go line of printed circuit boards, pin connection and wiring are likely to bring a larger parasitic inductance, thus resulting in high frequency power source waveform and waveform ripple and burr, and between power supply and to place a 0.1 F decoupling capacitor can effectively filter out the high frequency ripple and burr. If circuit boards using the patch capacitor, patch capacitance should be close to the components of the power supply pins. For the power conversion chip, or the power input, it is best to decorate a 10 F or larger capacitance, to further improve the quality of power supply.
(7) the serial number of components should be close to the components of the border to decorate, uniform size, direction and tidy, not with components, holes and overlap welding plate. Components or connector pins 1 said direction; Is the sign of the cathode should be clearly marked on the PCB, is not permitted to cover; Power conversion components (such as DC/DC converter, linear transformation power supply and switching power supply) side should have enough heat dissipation space and installation space, with sufficient welding outer space, etc.
2.2 general principles of the components wiring
Design personnel in the process of PCB wiring needs to follow the general principles are as follows.
(1) components printed line spacing of setting principles. Amount of space between different network constraints are produced by electric insulation, process and component size and other factors. Such as a pin spacing is 8 mil chip components, then the chip of the Clearance Constraint] cannot be set to 10 mil, designers need to separate this chip set a 6 mil design rules. At the same time, the distance between set to take into account the manufacturers production capacity.
In addition, the influence of components is an important factor in electrical insulation, if two components or network of potential difference is bigger, be considered for electrical insulation problems. Clearance in general environment safe voltage of 200 V/mm, or 5.08 V/mil. So when the same piece of circuit board when there are both high voltage circuit and low voltage circuit, you need to pay special attention to enough safe distance.
(2) line corner the choice of the form of line. In order to make the circuit board is easy to manufacture and beautiful, in the corner of the design need to set the line pattern, can choose to 45 , 90 and arc. Generally do not use the sharp corner, had better use circular arc transition or 45 transition, the 90 or avoid more sharp corner transition.
Between wires and solder joint is smooth as far as possible, avoid the small feet, tears filling method can be used to solve. When the center distance between the welding plate is smaller than a bonding pad diameter D, the width of the wire may be the same and the diameter of the welding plate; If the center distance between the welding plate is greater than the D, the width of the wire is not greater than the diameter of the welding plate.
Wire through between two bonding pad and not connected with, should keep their largest and equal spacing, the same uniform spacing between the wire and cable should be equal and maintain maximum.
(3) printed line width determination method. By wire line width is effected through the current level and anti-jamming and so on factors, the greater the flow through the current, the line should be more wide. Power cord should be wider than signal lines. In order to guarantee the stability of the ground potential (affected by changes to current size small), ground wire should be wider. Experimental results show: when printed wire of copper film thickness is 0.05 mm, printed wire carrying capacity can be calculated, according to the 20 a/was 0.05 mm thick, 1 mm wide wire can be through the current of 1 a. So for the general line 10 ~ 30 mil width can meet the requirements; High voltage, large current signal lines wide in the equal to 40 mil, line to line spacing greater than 30 mil. In order to guarantee the peel strength of the wire and working reliability, to the extent permitted in the plate area and density, as wide as possible wire should be used to reduce the line impedance, and improve the anti-jamming ability.
For the power cord and the width of the ground, to ensure the stability of the waveform, under the condition of the circuit board wiring space allows, bold as far as possible, normally need at least 50 mil.
(4) printed wiring of anti-interference and electromagnetic shielding. The main interference wires are introduced by the interference between wires, power supply cord into the the crosstalk between the interference and signal lines, reasonable arrangement and layout of line and grounding method can effectively reduce the interference sources, make the design of the circuit board has better emc performance.
For high frequency or some other important signal, such as the clock signal, on the one hand, it will try to get the line width, on the other hand can take the form of package to make the signal lines around it with isolated (is to use a closed ground will signal lines "package", is equivalent to add a layer of earth shield).
For analog ground and digital ground to separate wiring, cannot mix. If you need the uniform analog ground and digital ground for a potential, often should adopt the way of one-point earthing, which is to select only one point connect analog ground and digital ground, prevent a ground loop, and create the potential deviation.
After completion of the wiring should be at the top and bottom place without laying wires apply to large area of the grounding copper film, also known as coated copper, used to reduce the ground impedance, thereby weakening the high frequency signal, the ground at the same time, large area ground can have inhibitory effect on electromagnetic interference.
One of the circuit board via brings about 10 pf parasitic capacitance, is especially detrimental for high-speed circuit; At the same time, too many holes would also reduce PCB mechanical strength. Therefore, when wiring, should as far as possible to reduce the amount of the through hole. In addition, in the use of transmission through hole (hole), commonly used solder instead. This is because the circuit board, which may be because some causes of processing of transmission via (hole) were not wearing, and bonding pad must be through when processing, this also is equivalent to brought convenient to produce.
The above is the general principles of the PCB layout and wiring, but in practice, the layout of the components and wiring is still a very flexible work, the layout and the connections of the components is not the only way, the result of the layout to a large extent depends on the designers experience and thoughts. Can say, there is no a standard to judge the layout and wiring scheme of right and wrong, and can only compare relatively better. So the above layout and wiring principle as a design reference only, the practice is the only standard of judgment.
2.3 the special requirements of multilayer PCB layout and wiring
Compared with the simple single plate and double board, multilayer PCB layout and wiring has its unique requirements. For multilayer PCB layout, sum up is to arrange the different power supply and the layout of the types of components. Its purpose is to bring electricity in the back of the segmentation is convenient, but also can effectively improve the anti-interference ability of between components.
The so-called reasonable arrangement of the power supply and to the layout of the type of components, is to use the same power level and the same type of components together as far as possible. For example, when a + on circuit principle diagram, + 5 V, 3.3 V? 5 v, + 15 v,? 15 v, voltage grade, the designer should use the same voltage grade of components placed centrally in the circuit board of a certain area. Certainly is not the only standard of the layout, the layout principles as well as the layout of the other principles should be considered (the general principles of the double board layout), which requires the designer according to the actual demand to comprehensive consideration of various factors, to meet other layout principle, on the basis of as far as possible will use the same power level and type of components together. For multilayer PCB wiring, sum up is: go signal lines and go after the power cord. This is because the power of the sandwich plate and is usually done by electric connection within the layer. The advantage is to simplify signal layer go line, and the electrical layer through the large area of copper film connection way to effectively reduce the grounding impedance and power equivalent resistance, improve the anti- interference ability of the circuit; At the same time, the large area of copper film is allowed by the maximum current is increased.
Under normal circumstances, the designers need to type first reasonable arrangement of the power supply and the layout of the components, both other layout principles, and then according to the method introduced in the previous section for wiring components (only), after the completion of the split within electrical layer, determine the electrical layer network label of each part, finally through on electricity and signal layers in the hole and the bonding pad for connection. Welding plate and a hole through the electrical layer, and with the same network label from the bonding pad or some not corrode copper film is connected to the electricity layer, and does not belong to the network around the welding plate corrosion of copper film is completely off, that is not with the electrical conduction layer.
3. The middle tier to create and set up
Layer, is in the PCB layers between the top and bottom, the structure shown in figure 1-1, readers can understand the annotations in the reference. The middle layer in the process of production is how to implement? Simply sandwich plate is to suppress multiple single plate and double plate, the middle layer is the original single panel and double panel at the top or bottom. In PCB production process, you first need to on a substrate (generally using synthetic resin material) on both sides of the apply of copper film, and then through light painting and other technology transfer drawings of wire connection relationship to the PCB board (printed in drawing wire, welding plate and the hole coated to protect it, and prevent the part of the copper film corrosion in the corrosion process), and then by means of chemical etching (FeCl3 or H2O2 as the main component of corrosion liquid) there will be no corrosion protection of copper film laminating machine, finally complete drilling, silk-screen printing layer and so on post-processing work, such basic completed a PCB board. Similarly, multilayer PCB is in more than one plate layer adopts the suppression process again after the completion of the compressed into a piece of circuit board, and to reduce the cost and via interference, multilayer PCB often was not much thicker than the double plate and single board, which makes up of multilayer PCB board layer relative to the ordinary double-layer plate and the thickness of single layer board often smaller, lower mechanical strength, higher demand for processing. So the multilayer PCB production costs compared with the ordinary double plate and the single board will be expensive.
But because of the existence of the middle layer of a multilayer wiring more easily, this is also the main purpose of the sandwich plate. In practice, however, multilayer PCB threatening the manual wiring put forward higher request, makes the designers need to get more help of EDA software; At the same time, the existence of the middle tier can makes the power supply and signal transmission in the different layers of plate, the signal isolation and anti-jamming performance will be better, and the widespread application of copper connect power and ground network can effectively reduce the line impedance, and decrease for common grounding caused land potential deviation. So often use a multilayer structure of the PCB board than ordinary double-layer plate and the monolayer plate has better anti-jamming performance.
3.1 the creation of a middle tier
Settings provides a special Layer in the Protel system and management tools - Layer Stack Manager (the Layer Stack Manager). This tool can help the designer to add, modify, and delete the work layer, and the properties of the layer are defined and modified. Select [Design] / [the Layer Stack Manager..." Command, the pop-up as shown in figure 11-2 layer stack manager properties dialog box.
Pictured above is a 4 layer PCB layer stack manager interface. In addition to the top (TopLayer) and bottom (BottomLayer), there are two internal Power supply layer (Power) and the ground plane (GND), the position of these layers are clearly shown in the figure. Double-click on the layers name or click the Properties button to pop up layer Properties dialog box, as shown in figure 11-3.
There are three options in the dialog box can be set.
(1) Name is used to specify the Name of the layer.
(2) Copper thickness: specify the layer thickness of Copper film, the default value is 1.4 mil. The thicker the copper film is the same width of the wire can withstand the greater carrying capacity.
(3) the Net name: in the drop-down list to specify the layer network is connected. This option can only be used to set the electricity layer, signal layer without this option. If the inside electrode layer is only one network "+ 5 v", for example, you can specify here network name; But if the electrical layer needs to be split into several different areas, then dont specify the network name here.
In between the layers and insulation material as a carrier of the circuit board, or used for electrical isolation. Which is the Core and Prepreg insulation materials, but the Core is the double-sided has copper film and the connections of the plank, and segregation of Prepreg is only used for layer insulation material. Both the Properties of the same Settings dialog box, and then double-click the Core or Prepreg, or click the Properties button to pop up after insulation materials insulation property Settings dialog. As shown in figure 11-4.
The thickness of the insulating layer and interlayer pressure, related factors, such as signal coupling, etc, in front of the layer selection and superposition principle has been introduced. If there is no special requirements, generally choose the default values.
In addition to the "Core" and "Prepreg" two kinds of insulating layer, and usually have the bottom on the top of the circuit board insulation. Click on the Top left corner of the figure 11-2 Top Dielectric Dielectric (top-level insulation) or Bottom (the underlying insulation) before the selection box choose whether to display insulation layer, click the Settings button to the right of the insulation properties.
To set the options at the top and bottom insulation Layer has a cascade mode selection drop-down list below, you can choose different transfer mode: LayerPairs Layer (in Pairs), Internal Layer Pairs (electrical Layer Pairs) and Build - up (important). Mentioned in front, sandwich plate is actually made up of multiple suppression and double board or single board, choose different patterns, said pressed by different methods in the actual production, so as shown in figure 11-5 of the "Core" and "Prepreg" position is also different. Layer model in pairs, for example, is the two double powder an insulating layer (Prepreg), electric layer model is two single powder in pairs within a double plate. Layer usually USES the default Layer Pairs (in Pairs) model.
In the layer shown in figure 11-2 stack manager properties Settings dialog box on the right side of a column layer button operation, the function of each button below.
(1) the Add Layer: Add signal Layer in the middle. For example, the need to add a high-speed signal between the GND and Power layer, should first choose GND layer, as shown in figure 11-6. Click Add Layer button, can Add a signal under the GND Layer Layer, as shown in figure 11 to 7, the default name for MidLayer1, MidLayer2 ... and so on. Double-click on the layers name or click the Properties button to set the layer Properties.
(2) the Add parts relate: Add the electrical layer. Adding methods and adding signal layer of the same. First choice needs to be added in the position of the electrode layer, and then click the button, the electric layer within the specified layer below add, the default name for Internal Plane1, InternalPlane2,? , and so on. Double-click on the layers name or click the Properties button to set the layer Properties.
(3) Delete: Delete a layer. In addition to the top and the bottom cant be deleted, other signal layer and inner layer can be deleted, but the wiring in the middle of the signal layer and layer has been integral in electricity cannot be deleted. Choose need to delete the layer, click the button, the pop-up dialog box shown in figure 11-8, click Yes button, the layer is removed.
(4) Move Up, Move Up a layer. Choice needs to move up the layer (layer can be a signal, it can also be electric layer), click the button, then the layer move a layer at the meeting, but not more than the top.
(5) Move Down, Move Down a layer. Similar to Move Up button, click the button, the layer will Move down a layer, but not more than the bottom.
(6) the Properties: Properties button. Click the button, the pop-up similar as shown in figure 11-3 the layer properties dialog box.
3.2 the middle tier of Settings
Completion of the layer stack manager related Settings, click the OK button to exit the layer stack manager, can be done in PCB editor interface related operations. On the middle layer operation, need to first set up the middle layer is displayed in the PCB editor interface. Select "Design"/" Options..." Command, the pop-up as shown in figure 11 to 9 option Settings dialog box, under an Internal planes of the electricity option box only, display inner electrode layer.
After the complete set, you can see at the bottom of the PCB editor environment display layer, as shown in figure 11 to 10. Use the mouse to click on the PCB board label can switch different layers to operate. If not used to the system default color, you can select "Tools"/" Preferences..." Under the command of Colors options for a custom color of each layer, the related content has been introduced in chapter 8, for readers reference.
4. The electrical layer design
Sandwich plate relative to the ordinary double plate and single board is a very important advantage of signal and power can be distributed on the different plate layer, increase the degree of signal isolation and anti-jamming performance. Electricity within a copper film layer, the copper film is divided into several isolated areas, each area of the copper film through a hole with a particular power or ground is linked together, so as to simplify the power and ground network line, at the same time can effectively reduce power resistance.
4.1 electrical layer design related
Electric layer is usually within the whole sheet copper film, and the welding of copper film with the same network name plate inside through electrical layer when the system will automatically connect with the copper film. Bonding pad/through the inner hole and connection of electric layer, and copper film and other do not belong to the network the safety of the welding plate spacing can be on the Power Plane Clearance option Settings. Selection/Design Rules... Command, click the Manufacturing options, including the Power of Plane Clearance and Power Plane Connect Style options associated with electrical layer inside, its content is introduced as follows.
(1). The Power Plane Clearance
This rule is used to set the electric layer security spacing, mainly refers to no Internet connection and the electrical layer of bonding pad and the hole and the electrical layer security spacing, as shown in figure 11 to 11. At the time of manufacture, no Internet connection and the electrical layer of bonding pad in through electrical layer around the copper film is corrosion, corrosion of the size of the ring is, the value of the constraint set.
(2). The Power Plane Connect Style
This rule is used to set the electric welding plate and the layer forms. Mainly refers to a network connection with the electrical layer within the welding plate and the hole and the electrical connection between the form. As shown in figure 11-12.
Click the Properties (attributes) button, pop-up its rules Settings dialog box, as shown in figure 11-13. , the applicable scope of the rules on the left side of the dialog box to Rule the Attributes on the right side of the drop-down list to choose connection mode: Relief Connect, Direct Connect and No Connect. Direct Connect directly connected, the electric welding plate inside through layer did not drop the copper film around the corrosion, electric welding plate and inside layer copper film directly connected; No connect to show No connection, that is, with the copper film network bonding pad of the same name will not be connected to the inside electrode layer; Designers usually use the system default Relief Connect connection forms, the rules of the Settings dialog box shown in figure 11-13.
The solder joint forms through the Conductor extension and keep connected with electric layer within the insulation clearance, which in the Conductor Width option set the export of Conductor Width; Conductors export, the number of options in the conductor can choose 2 or 4; The width of Expansion option set in the conductor extension; Air - Gap options set in the insulating Gap width.
4.2 electrical layer segmentation method
In the previous sections of this chapter has introduced the choice of a multilayer laminated structure, the establishment of electric layer and related set inside, within this section mainly introduce a multilayer electric layer segmentation methods, steps and the reference for readers.
(1) before the layer division within the electricity, you first need to define an inner layer, it has been introduced in the previous section, this place is no longer here. Select [Design] / [Split Planes... ] Command, the pop-up as shown in figure 11-14 of electric layer dialog segmentation. The dialog box in the Current split planes bar in electric layer has integral area of the middle finger. In this case, the electrical layer has not been split, shown in figure 11-14, so the Current split planes column is blank. Under the Current split planes of the Add, Edit, and Delete button to Add new power supply area respectively, to Edit the selected network and to Delete the selected network. Button at the bottom of the Show Selected Split Plane View option is used to set whether to display the current select layer in electric diagram of the segmentation area. If you select this option, will show up in electric in the box below the layer is divided by the area in the area of thumbnails, among them with electrical layer network within the pins of the same name, bonding pad or the attachment will be highlighted in the thumbnail, dont choose this option is not highlighted. Show Net For options, select this option, if within the defined within the electrical layer has to the electrical layer specifies the network, is shown in the options at the top of the box with the network connection and pins with the same situation.
(2) click the Add button, the pop-up as shown in figure 11 to 15 electricity layer division in Settings dialog.
As shown in figure 11 to 15 in the dialog, Track Width used to set the drawing border line Width, but also in the electric network within the same region between the insulation of the spacing, so usually will Track Width is larger. Suggest that readers will input unit when the input value. If there only enter Numbers, not the input unit, the system will default to the current PCB units in the editor.
Within segmentation of the specified Layer option is used to set electric Layer, here can choose electric Power &gnd inside Layer. In this case, there are many kinds of voltage grade, so you need to split the Power within the electrical layer to provide different levels of voltage components.
Connect to the.net option is used to specify the divided region is connected network. Usually in electric layer is used for power supply and network layout, but in the Connect to Net the drop-down list as you can see, the inner layer of the whole network can be connected to the network signal, used in signal transmission, dont just general designer. Weak signals required by the voltage and current, small requirement to the wire, and power supply current is big, need a smaller equivalent internal resistance. So general signal in signal layer line, dedicated to the power supply and electrical layer network connections.
(3) click on the figure 11-15 electricity layer segmentation OK button in the dialog box, enter the network area borders drawn state. Electric layer frame in the drawing, the user generally will be other levels of information hiding, only show the current editor of power within the layer, convenient for frame drawing. Select "Tools"/" Preferences..." Command, the pop-up dialog box shown in figure 11-16. Select the Display options, and then choose the Single Layer Mode check box, as shown in figure 11-16. So, in addition to the current working layer Power, the remaining layers are hidden, display as shown in figure 11-17.
Electric layer within the division, because the integral area will all the networks pin and welding plate are included, so users often need to know the pins with the same name with the power supply network and the distribution of welding plate, for segmentation. On the left side of the tool, Select the VCC network Browse PCB (as shown in figure 11 to 18), click the Select button will light up the network selection.
As shown in figure 11-19 for the VCC network lit after selection, network Numbers as VCC welding plate and pin with other network label welding plate and pin. Chose the same network after welding plate, when drawing the boundary can divide these pads are incl, , uded in the range. At this time the power network can not through signal layer of attachment but directly through the welding plate is connected to the ele, ctrode layer.
(4) in electrical layer segmentation area of the drawing.
Select [Design] / [Split Planes... ] Command, the pop-up as shown in figure 11-14 of electric layer dialog segmentation, click the Add button, the pop-up as shown in figure 11 to 15 electricity layer division in Settings dialog. First select the 12 v network, click the OK button, the cursor into a cross shape, at this point you can layer, electricity to dividing up the work.
When drawing frame border, can press "Shift + spacebar" to change the corner of the walk line shape, also can press the Tab key to change the electrical layer properties. After drawing a closed area (start and end overlap), the system automatically pop up as shown in figure 11-20 of electric layer dialog, segmentation in the dialog box you can see an area has been split, in PCB editor interface display as shown in figure 11-21.
After adding the inside electrode layer, a larger 12 v pad, you can see the solder not connected to wires (as shown in figure 11-22 (a)), but in appeared on the bonding pad of a "+" sign, said that the bonding pad is connected and inner electrode layer.
The current work layer switch to Power, you can see the solder layer, electric connection status. Due to the electrical layer is usually the whole sheet copper film, so the figure 11-22 (b) in the welding plate as shown in the surrounding parts will be corroded in the production process, visible GND and layer within the electric insulation.
After adding 12V ??inner layer region may also add other network according to actual needs, the Power that is the inner layer divided into several different mutually isolated regions, each connected to a different power networks. Finalize the results shown in Figure 11-23.
Within the complete electrical layer after segmentation, can be in as shown in figure 11-20 of the dialog box to edit and delete has placed within the electrical layer network. Click the Edit button will pop up as shown in figure 11-15 of the electrical layer properties dialog box, in the dialog box you can change the electric layer upon layer surface in the line width, and the connection of the network, but cant modify the shape of the border. If not satisfied with the boundary and shape the direction of the, click the Delete button, only redraw boundaries; Or choose [Edit] / [Move] / [Split Plane] command to modify the electrical boundary layer, the control point on the moving boundary to change the shape of the boundary, as shown in figure 11-24. After the completion of the confirmation dialog click Yes button in the pop-up redrawn to complete.
After adding 12V inner layer region may also add other network according to actual needs, the Power that is the inner layer divided into several different mutually isolated regions, each connected to a different power networks. Finalize the results shown in Figure 11-23.
After completion of the split within the layer, you can edit and delete have been placed within the network layer in the dialog box shown in Figure 11-20. Click the Edit button to pop up the layer properties dialog box shown in Figure 11-15 shown in this dialog box you can modify the border line width, the surface layers of electrical and network connections, but can not modify the shape of the boundary. If you are not satisfied with the direction and shape of the border, you can only click the Delete button to redraw the boundaries; or select [Edit] / [Move] / [Split Plane Vertices] command to modify the layer boundary line, this time by moving the control points to change the shape of the boundary of the boundary, as shown in Figure 11-24. Upon completion of the confirmation dialog box, click the Yes button to complete redraw.
Problems. So to try to ensure that the PCB design boundaries without going through the pads with the same network name.
( 3 ) when the boundary layer in the drawing , due to objective reasons , if not the same network to all the pads are included, the traces can then put these pads are connected via signal layers. However, in the practical application of multilayer boards , you should try to avoid this situation . Because if a signal layer traces the way these pads connected with the inner layer , which is equivalent to a larger resistor ( signal layer trace resistance ) and smaller resistance ( inner layer copper film resistor ) in series the key advantage is that the use of multilayer connect power and ground through a large area of the copper film to effectively reduce the line impedance , reducing PCB grounding resistance caused by ground shift , improved robustness. So in the actual design and should be avoided by wires connecting the power network .
( 4 ) the local network and the power distribution network in different layers of the electrical surface to play better electrical isolation and immunity effect.
( 5 ) For the SMD components , pads or vias can be placed at the pin to connect to the inner layer , can also lead to a short wire from the pin at ( stubby lead should try to reduce line impedance ) , and placed at the end of the wire to connect the pads and vias , as shown in Figure 11-27 .
( 6 ) placed on the decoupling capacitors . Mentioned in the vicinity of the chip should be placed 0.01F decoupling capacitors for power class chip , it should be placed 10 F or greater filter capacitor to filter circuits and ripple frequency interference , and with as short wire connected to the pin on the chip , and then connect to the inner layer through the pad .
( 7 ) If you do not split the layer , the inner layer of the Properties dialog box, select directly connected to the network can be, and no longer need the layer segmentation tool.
5. multilayer design principles Summary
1 ) . PCB components required libraries
(1) PCB board components used must be properly packaged , including part of the pin sizes , pin spacing, pin number , size , and direction of the border and the like.
(2) polar components ( electrolytic capacitors , diodes, transistors , etc. ) is negative or pin number should be in the library and PCB components on the PCB marked.
(3) PCB library components pin numbers and schematic components pin numbers should be consistent , for example, described in the previous section of the diode PCB library component library pin number and pin number principles inconsistent problems.
( 4 ) requires the use of a heat sink fins size components should be considered when drawing components , including packaging , components and heat sinks can become a form of drawing together the whole package.
( 5 ) internal diameter pin and pad components to match the inner diameter slightly larger than the pin pad size components to install .
2 ) . PCB component placement requirements
( 1) The components are arranged uniformly , the same functional module components should be as close to the arrangement .
( 2 ) using the same type of power supply and ground together in a network part is arranged as far as possible , in favor of the complete electrically connected to each other through the inner layer
Pick .
( 3 ) Interface components should be placed aside , with the string specified interface type , the wiring should leave a direction generally leads to the circuit board.
( 4 ) power conversion components ( such as transformers , DC / DC converters, three-terminal regulator , etc. ) should leave enough space for heat dissipation .Pin or reference point
( 5 ) components should be placed on the grid , in favor of wiring and beautiful.
( 6 ) filter capacitor can be placed in the back of the chip, close to the chip s power and ground pins .
( 7 ) The first pin or logo to identify the direction of the components should be marked on the PCB , components can not be overwritten .
( 8 ) label components should be close to the border components , uniform size , direction and tidy , do not overlap with the pads and vias can not be placed in yuan
The device after the installation area covered .
3 ) . PCB wiring requirements
( 1 ) should be isolated from the power supply different voltage levels , power traces should not cross .
( 2 ) traces the arc using 45 corner or around the corner , not allowed to have sharp corners form .
(3) PCB traces directly connected to the center pad , the pad is connected with the wire width must not exceed the size of the pad diameter.
( 4 ) high-frequency signal line width of not less than 20mil, external land lines surround , isolated from other ground .
( 5 ) the interference source (DC / DC converter , crystal, transformers, etc. ) do not bottom wiring to avoid interference .
( 6 ) as bold and ground power lines in space permitting, the width of the power cord is not less than 50mil.
( 7 ) low-voltage, low-current signal linewidth 9 ~ 30mil, under the circumstances as bold as space permits .
( 8 ) the spacing between the signal lines should be greater than 10mil, the power cord should be greater than the spacing between 20mil.
( 9 ) large current signal line width should be greater than 40mil, spacing should be greater than 30mil.
( 10 ) The minimum size is preferred outside diameter vias 40mil, the inner diameter of 28mil. When the connection between the top and bottom with a wire , preferably pads.
( 11 ) does not allow a signal line disposed on the inner layer .
( 12 ) within the width of the gap layer between the different regions is not less than 40mil.
( 13 ) when drawing boundaries , try not to let the pad area by the boundary line to connect to .
( 14 ) laid on the top and bottom copper , recommended to set the width greater than the width of the grid completely covers the free space , and does not leave dead copper , while maintaining 30mil (0.762mm) above the pitch line and the other ( copper can before setting safety spacing, change it back after the completion of the original copper safe spacing value ) .
( 15 ) After wiring is complete tear of the pad for processing .
( 16 ) device and an external metal shell module ground .
( 17 ) placed mounting and soldering pads .
(18) DRC check and correct.
4 ) . Layered PCB requirements
( 1 ) power plane should be close to ground level , there are tightly coupled with the ground plane and arranged under the ground plane.
( 2 ) the signal layer and the inner layer should be adjacent to other signals not directly adjacent layers .
( 3 ) the digital and analog circuit isolation. If conditions permit, the analog signal lines and digital signal lines layered arrangement and shielded
Measures ; If you need the same signal level layout , you need to use the buffer zone , the way to reduce the interference lines ; analog and digital circuits
The power and ground should be isolated from each other , can not be mixed .
( 4 ) high-frequency circuits of external interferences , the best individual arrangements using both the upper and lower layer directly adjacent to the intermediate layer to transmit a signal to take advantage of the copper film layer is to reduce external interference.
6, Multilayer PCB laminate technology
Printed circuit board according to the layer to have single panel, double panel and sandwich plate. The making craft of single and double panel is simple! This paper is in the process of Multilayer PCB laminate technology! Multilayer printed circuit board is composed of more than three layers of conductive graphics layer and insulation layer alternately by laminated gluing together and form of the PCB, and meet the design requirements stipulated conductive graphics interconnection between the layers. It has high density, small volume, light weight, high reliability, etc, output value is the highest, fastest growing type of PCB products. With towards high-speed, multi-functional electronic technology, large capacity and portable low consumption direction development, the application of multilayer printed circuit board is more and more widely, its layers and the density is becoming more and more high, the corresponding structure is becoming more and more complex. Laminated technology, refers to the use of half cure piece (by epoxy glass cloth dipping, baking to solvent is made of a sheet material. The resin B stage, under the effect of temperature and pressure, the liquid and can be quickly solidified and complete bonding.) The conductive graphics of gluing technology under high temperature and high pressure.
Multilayer PCB laminate technology according to the positioning system adopted by the different, can be divided into laminated before positioning system technology (PIN - LAN) and positioning system after laminated technology (MASS - LAM). The former location accuracy is high, but low efficiency, high cost, only applies to the number of high-level, high precision production of multilayer printed circuit board, and the latter while positioning accuracy is low, but high efficiency, low cost, so this method is the present domestic most of the PCB manufacturer for laminated process method is generally used to mass production.
1) before positioning system lamination technology
1.1 before positioning system introduction
Circuit graphics positioning system is throughout the multilayer film production, graphic transfer inside and outside layer, laminated and CNC drilling process, such as a common problems. Every layer of multilayer PCB circuit graphics, relative to other layers must be accurate positioning, to ensure that multi-layer PCB circuit between each layer can be correctly connected to the hole metallization. For the number of high-level, high density and large panels laminated is particularly important.
Review of a multilayer laminated making used pin positioning method, there are two round hole pin positioning method, a hole slot pin positioning method, three round hole or four round hole positioning method, and this article will introduce four slots positioning method. The positioning method is a Multiline company, using its provide a series of four slots positioning equipment, in the lining of the photographic template, to produce four slots on the single chip. Then use the corresponding four grooved pin to achieve graphics transfer, laminated, laminated and CNC drilling and a series of process of the position.
1.2 positioning system before laminating process
According to former positioning system of multilayer PCB laminate, mostly adopts the single chip laminated technology in the past, in the process of the whole inner graphic production, of one side of the external layer of protection, not only brought trouble to make, and the production efficiency is low; Especially for four layer board can produce the problem such as the plate warping. The copper foil laminated technology widely used now, every mouth can suppress 2 ~ 3 pieces, improve the production efficiency, and fundamentally solve the four layer board surface buckling problem in production. (if using laminated after positioning system, while still using the same press, as a result of not using heavy molds, protect the compressor every opening can be suppressed even 6 piece of sandwich plate.) Here is only a brief introduction to the copper foil laminated technology USES.
(1) a curing slice preparation
(a) in clean and dust-free environment, will be cut into strip coil, and then use paper cutting knife cut into piece, size according to the monolithic blank width enlarge to 10 mm;
(b) in the positioning hole position, into a pile with a bench drill positioning hole, aperture is bigger than locating pin diameter 1.5 ~ 2.0 mm;
(c) every half piece has broken fiber, big grain on curing glue, impurity defects should be removed, operation should be Dai Qingjie yarn gloves, it is strictly prohibited to hand sweat, oil pollution;
(d) cutting half curing, to wear a mask to avoid inhaling powder tree. Wear gown trousers, avoid tree powder stick to the skin and cause itching or irritation. At the same time, should avoid tree powder into eyes;
(e) cutting processing good half cure piece, should be promptly put in more than 1 x 10-1 Tuo vacuum ark, excluding volatile and damp, ban into the oven or refrigerator and moisture, prevent aging, bonding. In a vacuum storage cabinet platoon is wet should be greater than 48 hours
(f) should be carried out on the new half curing performance measurement. As the growth of the storage period, material aging, directly affect the fluidity and gelation time, it is closely related to the quality of the product, is the basis of process parameters. On performance measurement and calculation, see the section quality control.
(2) inner monolithic black and dry
(a) the inner black PCB process
upper plate → unoil → wash →wash → Microetching → The secondary countercurrent washing → preimpregnation → melanism → wash → wash → Also protect the → hot wash → wash→The lower
(b) using ammat company provides the darkening of the solution;
(c) the corrosion rate control range: 1.0 2.0 mu m/cycle.
(d) black weighing control range: 0.2 0.35 mg/cm2.
(e) after the appearance of the dry, the surface is black, graze without black powder falling;
(f) inspection after laminated peel strength test, the peeling strength should be above 2.0 N/mm;
(g) after the black single chip with hook hanging in the electrothermal constant temperature drying box, 90 ~ 100 ℃, drying at least 60 minutes.
( 3 ) Other requirements before loading mode
(a) new leader of die application will protect the oil clean gasoline at the surface should be cleared with the mold resin dust, dirt , can not scratch the surface of the cleaning process , the mold surface may not have pits and projections of particles ;
(b) with 0.05mm polyester film for stripping material, to prevent the outflow of epoxy resin and die bonding, die cut material dimension greater than about 15 ~ 20mm, the site of punching or drilling dowel pins , dowel pins aperture greater than 2mm ;
(c) hobs should pad about 10 layers of kraft paper , on the one hand as a buffer layer of heat transfer , while protecting the furnace board without strain. For uneven mold , pin up on the die, the die size less than 200mm × 200mm who should be the appropriate measures, or does not allow direct pressure to prevent the causing local deformation , damage stove plate flatness ;
(d) prepreg model number of sheets of prepreg fill should be based on the total thickness of the inner piece , product design thickness requirements or process card labeling process requirements, while pressing the actually used , the actual performance and the actual thickness of the pressure test after to decide ( fill prepreg , 1080 shall not be less than two , to prevent the phenomenon of micro- bubbles caused due to insufficient amount of glue ) ;
(e) For larger mold weight and prevent injured and out of the mold .
( 4 ) into the mold preload
Prior to preload into the mold , the press should be heated to 175 ± 2 ℃, into the mold to ensure begin immediately after lamination .
(a) 100T PHI press :
Pre- pressure : 0.8 ~ 1.5Mpa (8 ~ 15 kg / cm ) , time: 4 to 8 minutes ;
(b) 140T really Compressor (OEM companies ) :
Pre- pressure : 0.56 ~ 0.7Mpa (80 ~ 100 lbs. / Square inch ) , Time: 7 to 8 minutes ;
After preloading squish one minute ;
(c) after preloading pressure applied into the mold , the size is generally determined by the prepreg situation . When prepreg flow was reduced, may be appropriate to increase the preload pressure.
(d) Characteristics time by preloading stage prepreg , laminating temperature , buffer paper thickness , size of PCB and PCB layers affected .
If preloading period is too short , the full pressure is applied too early will cause excessive loss of resin , and in severe shortage of rubber , layered ; If preloading period is too long , too late, that full pressure is applied between layers of air and volatiles copies are not completely excluded , the gap has not been filled resin will produce bubbles and other defects in the multilayer . Therefore , it is important to grasp the opportunity to pressure changes .
When the prepreg flow index below 30 %, should be shortened pre-press time , or even directly from full pressure operation.
In short , due to the characteristics of the relationship between pre-press cycle and prepreg very close, pre-press cycle is not the same level , pressure test must be passed in multilayer laminated good basis for a comprehensive inspection on the pre- pressure cycles make the appropriate adjustments before formally put into production .
(5) ShiQuan pressure and heat/pressure
After the preloading, on the premise of keeping constant temperature, turn pressure ShiQuan operation. And according to the requirements of the process parameters of heat/pressure.
(a) 100 t PHI press:
All pressure: 1.5 ~ 3.0 Mpa (15 ~ 30 kg/cm2), time: 90 minutes;
(b) 140 t vacuum compressor (OEM) : All pressure: 1.12 ~ 1.4 Mpa (160 ~ 200 pounds per square inch), time: 80 minutes;
(c) when half cure piece of fluidity decrease, can be appropriately increased pressure. Completely finished bubble, caulking, ensure that the thickness and the best resin content.
(d) pressure switches used high temperature transformation way. When half the curing temperature of up to 115 ~ 125 ℃, from preloading to total pressure.
(6) temperature preservation pressure (cold) Total pressure and heat/pressure after the operation, cold press operation can adopt the following ways:
(a) stop heat press, under the condition of the pressure unchanged, laminate cooling to room temperature;
(b) laminate to cold press machine, cold press operation.
(7) the mold, mold release
(a) after the laminate temperature down to room temperature, open press, take out the mold;
(b) on the demoulding special work table, remove the mould pin, remove the laminate.
(8) to remove waste flow glue edge
(a) laminated discharge residual glue, irregular salivate, thickness is not consistent, to ensure that after the punching and application shears to scrap edge cutting, cutting to the edge of blank, but it can't destroy the positioning hole;
(b) when the board face appear distorted or bow bend uneven phenomenon, should be dealt with leveling, warps quantity control in the range of 0.5% of the diagonal.
(9) print Numbers
After pressing the multilayer board of semi-finished products, the two outer for copper foil, to prevent confusion, immediately with seal characters on the blank of product profile for print out the figure number and suppress record number, the handwriting must be clear, does not cause the wrong number.
(10) after curing processing
Board to be included in the electrothermal constant temperature drying box, heated to 140 ℃ and keep 4 hours.
2) after laminated positioning system technology
2.1 after positioning system introduction
After positioning system is adopted to improve the multilayer printed circuit board production, without multilayer positioning equipment, direct use of copper foil and half cured. And adopts the production of the base material for copper-clad laminated, besides saving laminated positioning device, also it can save and the inner line production layer of protection of dry film and production operation; In addition, the base material and equipment, can be fully used to increase the number of press each opening of the platen, improve production efficiency.
Particular way is: (1) in each inner graphics border lines, according to the technological requirements add 3 hole location hole mark;
(2) inner graphics border lines outside the four corners, according to the technological requirements add tool hole mark;
(3) to make the inner graphics, and in the corners of coining tool hole;
(4) inner black of single chip processing;
(5) laminated front panel operation (for more than four layers of laminated, by means of special rivets in among the inner hole located in riveting, to ensure that the interlayer contact ratio; among the inner fill half cure piece according to the requirements of process.) ;
(6) according to the technological requirements for laminating operation;
(7) plate, hole line, secondary shear plate, in the position for milling copper, drill positioning hole operation.
2.2 positioning system after laminating process
Cutting half cure piece→ The inner single piece of black →The inner walkthrough plate → Row plate → laminated → patch→ Some hole line → After the cutting board → Making plate, → After the baking plate →Milling to positioning hole copper sheet →Positioning hole →The quality inspection
(1) cutting half cured
Half of the roll will solidify size requirements as stipulated in the process, on the special curing cutting machine cut into the required size of the chunks. Half curing types mainly include 1080, 2116 and 7628.
(a) According to the specified materials and plate process, calculation need to cut half piece of the number of curing;
(b) cutting half cure piece before (and after), need to clean the table;
(c) pulling away half cure piece from the roller shelf to the required size, after cutting,
(d) after cutting each volume, need a vacuum cleaner gettering sala tree of powder;
(e) Dai Qingjie gloves during operation;
(f) resin cloth do not flex, do not have any impurities, and maintain dry resin cloth;
(g) All landowners cut half piece of purifying workshop to curing, and control the temperature and humidity.
According to the requirements of the above half of cutting piece can be directly used in curing row plate and then laminating production.
(2) inner monolithic black
(a) inner monolithic darkening use: in addition to the oil - micro corrosion - presoak - black - after leaching process;
(b) using the Mac Dermid company provides the black liquid medicine;
(c) after the black plate of drying condition is: temperature 110 ~ 120 ℃ 45 minutes;
(d) after the black plate in a row between the storage time of valid for 48 hours.
(3) the inner walkthrough board
More than six layer and layer of the multilayer needs for the operation.
(a) according to the selection process indicating the inner half of black monolithic between curing type and quantity;
(b) according to the single tool hole position on the half cure piece of round hole punch the corresponding;
(c) will be half of black monolithic and intermediate sandwich curing in tool hole position, using special rivet rivet;
(d) the operation should be carried out within the purification room, and the need for temperature and humidity control.
(4) row plate
Will be approved by black treated four layer board or the walkthrough plate after six layer and above board, according to the process of the drainage plate method and half-and-half curing to the request of the quantity and size and outer copper foil, in a BOOK.
(a) the base plate and the fixed number of kraft paper, shipped to the special line of plate on the table;
(b) according to the technological requirements check half solidification and copper foil;
(c) with a special wax cloth clean steel plate, and placed in a brown paper;
(d) put the copper foil on the steel plate, pay attention to smooth down, then with wax between steel and copper foil clean once again: (there is also a clean steel and copper foil in advance, and USES the hot melt adhesive stick method of copper foil will stick together.)
(e) half of the required curing on the copper foil, perhaps with a clear sundry;
( f ). Put the lining board on the resin cloth, eliminate possible adhesion on the lining plate of debris (with makeup, need according to the technological requirements for the arrangement of inner plate);
(g) All landowners puts half cure piece of lining board (placed before must flip);
(h) Today the required of the copper foil on half cure piece, copper foil smooth upward;
(i) Pet-name ruby with wax cloth to clean the copper foil surface, and at the same time puts good clean side of the plate on the copper foil;
(j) Attending again another surface clean steel plate;
(k) repeated (d) to attending the operation until the complete process of every BOOK number of laminated composite board;
(l) the required number of kraft paper on the steel plate, and then put the aluminum panel on the kraft paper, this BOOK plate is complete.
(5) the laminated
program temperature increasing and adopted by preloading by turn pressure until the high pressure laminated model. Press used for 800 t vacuum laminating machine, for the configuration of two hot-pressing machine, a cold press machine.
(a) before laminating, check that the oven door rubber edge is normal;
(b) charging, check whether the temperature at 155 ~ 165 ℃
(c) according to the process of the laminated parameters, by analogy to adjust the pressure;
(d) for pressure plate charging, vacuum and 60 ~ 70 MMHG, hot pressing according to the technological requirements, the entire process takes about 140 minutes;
(e) will complete the hot plate to cold press machine, the calibration of pressure to 160 kg/cm2 for cold press operation, takes 80 minutes;
(f). Considering the cold press time, the two best hot press platen of interval time is 90 minutes.
(g) the laminating process, need to have automatic temperature curve drawing instrument, moreover has yet to record information about the clamp, is advantageous for the quality tracking. See the following table 3.
(6) patch
(a) discharge every BOOK in the top panel, remove the kraft paper;
(b) removal of steel plate, and clean; (all the steel plate must be separated with sponge pieces.)
(c) with the number plate with a marker pen to write on the edge, and placed in a movable table; (between separated with kraft paper board.
(d) repeat (2) - (3) the operation until the demolition of all board.
(7) hole line
(a)Reference process of plate method, in not decoloring pen points out three positioning hole position of each plate;
(b) and plate number of the corresponding template with a pencil, draw the corners of sheet metal;
(c) every six floors above board, point positioning hole or crossed, can first presented four hole tools and sheet metal in the four nail holes overlapping position right after, can point hole line.
(8) after cutting board
(a) the shear plane with kraft paper, paper can't touch any stains or debris;
(b) according to the process of the product appearance size, reference line position, after the school completed the shear size cutting board;
(c) after cut the first board, subject to size inspection. After qualified, cut the rest of the board;
(d) between the plate and the plate must be separated by kraft paper.
(e) Also can make the shape of the number plate frame in advance, puts the plate on the blanking. (can improve the production efficiency and the dimensions of consistency.)
(9) Making plate
Will play Shanghai the top right corner of each plate board, avoid the phenomenon of mixed plate. (operation, plate should be flat on the stage, do not end up in their hands, curved plate.)
(10) After the baking plate
Sheet contraction in stable condition, eliminate the failure to remove stress within the cold press, facilitate customer connect plate immediately after the drilling operation.
(a) will have a number plate of sheet metal, with wax cloth to clean on the surface, is consistent with the size of the kraft paper separation between plate;
(b) before charging, first clean every fold at the bottom of the thick steel plate, and then into the plate. Each pack no more than 15 pieces, each pile of thin plate panel should be placed a;
(c) the baking plate for 4 hours, the temperature control in 125 ~ 135 ℃ (each batch plate charging and released, all needs to fill in the record.)
(d) sheet after, need to cool to room temperature, can operation of next working procedure.
(11) milling to positioning hole copper sheet
Marking location hole cut size and location of the sandwich plate, using special milling surface copper of the copper sheet machine milling to positioning hole position, in order to arrange another procedure operation. (need kraft paper separate plate, and avoid scratching and wear and tear.)
(12) Positioning hole
Drone with laminated positioning hole is special and, in three positioning hole. (semi-automatic and fully automatic drone.)
About PCBway
Since 2003 PCBWAY has been the leading PCB quick turn manufacturer specializing in both Prototype and Production quantities, Initially produced single-sided and double-sided printed circuit boards for the consumer electronics market. PCBWAY is ranked among the top 4 board fabricators in asia and is well-known for its expedited turn time capabilities and its reliable best on-time shipping record.
Today, we have over 450 operators with high modern facilities to manufacture multi-layer PCB up to 12 layers. Backing up with a group of professional engineers, and well established quality system. PCBWay has grown to become a major PCB manufacturer in Asia to serve in diverse customers base such as electronics appliance, communication, educational electronics, power supplies, Automationsetc.
Our mission is to become one of leading PCB manufacturer that provide in high quality product with total customer satisfaction.
For more information about PCB, or to learn more about the online quote and ordering process, please visit //www.PCBway.com.
