Backplane PCB manufacturing has been a specialized nature of the product . Back thicker than conventional PCB board and heavy , and accordingly its heat capacity is also large . Given the slow cooling back , so to lengthen the length of reflow oven . It needs to be at the outlet of the forced air cooling to the temperature reduced to a backplate safety operation.
PCB backplane technology introduction
Users of the core layer is thinner , more layers need to bring back the opposite for the two delivery systems requirements . When there is a large power applications card into the backplane , copper layer thickness must be moderate in order to provide the necessary current to ensure that the card can work properly. All these factors result in increased average weight back , this requires additional conveyor belts and feeding system must be able not only to a large size sheet materials safely , but it must also be take into account the fact that the weight gain . Because back thicker than conventional PCB and drilling holes also much more, and therefore easily lead to processing liquid outflow phenomenon . In order to minimize the amount of fluid carrying the guide hole and eliminate any possibility of residual impurities and drying , high-pressure washing and air blower to clean the drilling method is extremely important.
Since more and more applications require the user board layers , layer alignment will become very important. Inter-layer alignment tolerances required convergence . This convergent plate size becomes more demanding ambassador . Patterning processes are all generated at a temperature and humidity controlled environment. Exposure device at the same environment, the entire area in front of the figure and the figure is 0.0125mm need to maintain tolerance requires the use of a CCD camera before and after the completion of the layout of the place. After etching , drilling system using four internal shelves perforation. Piercing through the circuit board, the position accuracy remains 0.025mm, repeatable capacity 0.0125mm. Piercing needle is then inserted into the pin , the inner layer of the etching position , while the inner layer are bonded together . Perforation after using this etching method can fully guarantee the drilling and etching copper aligned , forming a solid ring design structure. However, with the user requirements in terms of PCB traces in a smaller area laid more lines, the fixed costs of the board remain unchanged, the required etching copper smaller size , requiring better interlayer copper bit . Fixtures and equipment must be capable of transmitting simultaneously conveying large size and heavy plate panels .
In addition to the drilling requirements of the plating layer of uniform thickness , the outer layer backplane designers generally on the copper surface uniformity has different requirements. Some designs etched in the outer few signal lines . On the other hand , faced with high data rate and impedance control line demand , the external layer is disposed near solid copper foil becomes very necessary to make use of the EMC shield . Since the user requires more layers, thus ensuring etching before bonding to the inner layer defect identification and isolation is very critical . To achieve the effective impedance of the backplane and reproducibly controlled etch line width, thickness and tolerances become critical indicators . In this case, the method can be used to ensure AOI etched copper pattern and design data match. Using the impedance model by the AOI to set linewidth tolerance , in order to determine and control the impedance of the line width variation sensitivity.
Traditionally , for reliability reasons, tend to use passive components on the backplane . However, to maintain the active plate fixed costs , BGA more active devices on the backplane design . Component mounting apparatus must not only be able to put a smaller size capacitors and resistors , but also must be able to operate the additional silicon package components . In addition , the backplane large sets of standardized equipment required to install the bed should be large and heavy backplanes for fine positional tolerance can also be shifted.
PCB backplane design and detection points
Growing user can work in an increasingly complex for large-size high-bandwidth backplane under unprecedented demand , resulting in the need to go beyond the conventional PCB manufacturing line equipment processing capacity . Especially the larger back sizes, heavier , thicker , more piercing than standard PCB layers and requirements . In addition, they require width and tolerances become more sophisticated , we need a hybrid bus structure and assembly techniques.
Backplane PCB manufacturing has been a specialized nature of the product . The design parameters and most other boards are very different , the production needs to meet a number of stringent requirements, noise margin and backplane signal integrity design also requires compliance with specific design rules. These characteristics led to its backplane there is a huge difference in the equipment specifications and equipment and other manufacturing requirements.
Backplane size and weight requirements for the delivery system
The biggest difference between the conventional and the backplate is PCB board size, heavy weight and large raw material substrate (panel) processing problems . Standard size PCB manufacturing equipment for typical 24x24 inches. The user is required to telecommunications users , especially larger size backplane . Thus promoting the delivery tool for large-size panels recognition and purchase requirements. Designers to solve large pin-count connector alignment problems have an additional layer of copper to make the backplane layers increases. Stringent EMC requirements and impedance conditions increase the number of layers in the design to ensure sufficient shielding effect , reduce crosstalk , and to enhance the signal integrity.
When there is a large power applications card into the backplane , the thickness of the copper layer must be moderate in order to provide the required current , ensure that the card can work properly. All these factors lead to an increase in the average weight of the backplane , and this requires additional conveyor belt system must not only be able to transfer a large sized plate materials safely , and its weight must also be taken into account also the fact .
Users of the core layer thinner layers need more back on the conveyor system brings the two diametrically opposed requirements. Conveyors and conveying device can be hand picked and transported without damage to a thickness less than 0.10mm (0.004 inches) of large-size thin film, on the other hand must also be capable of delivering 10mm (0.394 inches) thick , 25 kg ( 56 lbs ) weight the board and the board can not afford .
Between the inner plate thickness (0.1mm, 0.004 inches) and the backplate thickness ( up to 10mm, 0.39 inch) away from the finished two orders of magnitude , which means the delivery system must be strong enough , they can be safely transferred through the processing zone . Because back thicker than conventional PCB and drilling holes also much more, and therefore easily lead to processing liquid outflow phenomenon . 30,000 holes of 10mm Heavy backplane specification , can be easily adsorbed to the surface tension by the guide holes in the machining liquid out a little . To minimize the amount of liquid carrying the guide hole and eliminate any possibility of drying the residual impurities , high pressure flushing and the air blower for cleaning the drilling method is extremely important .
Alignment layer
Due to an increasing number of applications require the user board layers , counterpoint between the layers will become very important. Inter-layer alignment tolerances required convergence . This convergent plate size becomes more demanding ambassador . All processes are layout at a certain temperature and humidity controlled environment produced . Exposure device at the same environment, the entire area in front of tolerance and Figure chart needs remain 0.0125mm (0.0005 inches). To achieve this accuracy , requires the use of a CCD camera before and after completion of the layout position .
After etching , drilling system using four internal shelves perforation. Piercing through the circuit board, the position accuracy remains 0.025mm (0.001 inch) repeatable capacity 0.0125mm (0.0005 inches). Piercing needle is then inserted into the pin , the position of the inner etched , while the inner layer are bonded together .
Initially , the use of such an etching method can be sufficiently perforated to ensure alignment of the drilling and etching the copper to form a cyclic rugged design structure . However, with the user requirements in a smaller area of the line laid in more PCB traces , the fixed costs of the board in order to maintain constant , the etching of the copper plate is required smaller size , requiring copper to better interlayer bit . To achieve this goal , the purchase of X-ray drilling machine approaches can be used. The device is able to achieve in 1092 × 813mm (43 × 32 in.) maximum size of the board to drill a hole position accuracy of 0.025mm (0.001 inch). Its usage in two ways:
1. observed by X -ray machines on each floor etched copper , with drilling to determine the best location.
2. drilling machine storage statistics, records deviation and divergence of bits of data relative to the theoretical values. This SPC data back to the front of the processing operations such as selection of raw materials , processing parameters and layout drawing , etc., in order to help reduce its rate of change , continuous improvement process .
Although any of the plating process the plating process is similar to the standard , but the large size of the unique characteristics of the backing plate , there are two main differences must be considered.
Fixtures and equipment must be capable of transmitting simultaneously conveying large size and heavy plate panels . 1092x813mm (43x32 inches ) the large size of raw materials base weight up to 25 kg ( 56 lbs ) . Substrate must be safely grasp the transport and processing . Processing tank (tank) must be designed to be deep enough to accommodate the board into, and the entire chamber must remain uniform plating characteristics.
In the past, users are press-fit backplane connector is specified , which relies on copper plating uniformity requirements overweight . Backplane thickness of 0.8mm to produce 10.0mm (0.03 inches to 0.394 inches ) of the variation . Existence of various aspect ratio and size of the substrate becomes large, so that the uniformity of the plating becomes critical indicators . To achieve the required performance uniform must be used periodically reverse ( "pulse " ) plating control equipment. Also, you must make the necessary agitation to maintain as uniform plating conditions .
In addition to the drilling requirements of the plating layer of uniform thickness , the uniformity of the copper backplane designers outer layer on the surface generally have different requirements . Some designs etched in the outer few signal lines . On the other hand , demand for high data rate and facing the impedance control circuit , disposed near the solid outer layer copper foil will become necessary to make use of the EMC shield .
Detect
Since the user requires more layers, and thus ensure that, before etching adhesive layer on the inner defect identification and isolation is very crucial. To achieve the effective impedance of the backplane and reproducibly controlled etch line width, thickness and tolerances become critical indicators . In this case , the method can be used to guarantee matching AOI etched copper pattern and design data . Using the impedance model by the AOI to set linewidth tolerance , in order to determine and control the impedance of the line width variations of sensitivity.
Backplane and the trend is placed on the active backplane large size multi- loop drilling , to jointly promote the conducting elements loaded in order to carry out strict inspection before the bare board necessary for efficient production .
Increasing the number of drill holes on the backplane means bare board test fixture will become very complicated , despite the use of special fixtures can greatly shorten the unit test time. To shorten the production process and prototype manufacturing time , using double-sided flying probe fixture, be programmed with the original design data , to ensure consistency with the user 's design requirements and reduce costs , shorten time to market.
PCB backplane for drilling
To solve a diamond drilling technique thick backplane PCB drilling , because the need to drill two holes drilled through to complete processing of drill positioning system design , drilling and processing of positive and negative sequence twice drilling drills have special requirements , such as the size of the design .
Preface:
Generally, we put in 4.0mm thickness above , the board member has a typical crimp hole design called PCB backplane. The main features of the backplane PCB board size is large , the current size exceeds has not uncommon 1000mm; high thickness , typically 4.0-6.0mm, sometimes even up to 10.0mm. In addition , the main row of holes for PCB backplane connector , customers dimensional tolerances that type of hole , hole copper quality , and even shaped hole has very strict requirements . Due to limitations of mechanical drilling capability , PCB backplane drilling technology is the whole process is a key factor . Solutions to technical problems drilling thick PCB backplane lot of drilling is one of them . Mechanical drilling technology breakthroughs for drilling capacity constraints of the problem , the drill can be completed without special custom backplane PCB drilling thick , thick PCB backplane for batch processing obvious advantages .
1 . The range of applications for drilling
Also known as the pros and cons of diamond drilling industry , is divided into two sides step to complete the drilling of a processing method , the first drill hole is controlled deep drilling , drill through the second hole . The drilling method because of the through holes drilled from the same two complete, requires two drilling location, thus high design requirements for Drill ! Usually due to poorly designed or positioned drilling drills twice the size of the design is unreasonable, there will be " stepped hole " defects have fatal consequences for the PCB assembly crimping devices.
PCB backplane row of jacks are very huge number of drill to drill two holes through the process to complete , in order to produce a reasonable use of resources , through trials to material type ( Our main five categories ) and the thickness of two parameter is the factor we identified in table I need to apply for drilling plate processing technology .
2 . The design of the positioning hole drilled
Conventional Drill holes into three general design , but because of the need to change the face of the diamond drilling process , the degree of alignment of the two boreholes demanding initial class board processing, is easy to operate, reducing the positive and negative drill errors caused by switching , we designed four positioning holes for positioning the center of the plate symmetrically . The advantage of this design is the positioning holes : the first controls the drilling depth of the pin hole without re- drilling , drilling only to reload the reverse plate can be eliminated to bring the two positioning pins play error . However, processing results show that four-hole positioning processing methods still have " stepped bore " bad produce .
In order to reduce the " stepped bore " bad , we use is called "over positioning" Drill method . MACHINERY will two or more repeating the positioning element limit the degree of freedom of a workpiece or a phenomenon known as over several positioning. For drilling for , just consider X, Y direction of the positioning method is: the positioning hole is designed to six , six plates are symmetrically positioned holes .
Technology Introduction
Backplane PCB manufacturing has been a specialized nature of the product . Back thicker than conventional PCB board and heavy , and accordingly its heat capacity is also large . Given the slow cooling back , so to lengthen the length of reflow oven . It needs to be at the outlet of the forced air cooling to the temperature reduced to a backplate safety operation.
Users of the core layer is thinner , more layers need to bring back the opposite for the two delivery systems requirements . When there is a large power applications card into the backplane , copper layer thickness must be moderate in order to provide the necessary current to ensure that the card can work properly. All these factors result in increased average weight back , this requires additional conveyor belts and feeding system must be able not only to a large size sheet materials safely , but it must also be take into account the fact that the weight gain . Because back thicker than conventional PCB and drilling holes also much more, and therefore easily lead to processing liquid outflow phenomenon . In order to minimize the amount of fluid carrying the guide hole and eliminate any possibility of residual impurities and drying , high-pressure washing and air blower to clean the drilling method is extremely important.
Since more and more applications require the user board layers , layer alignment will become very important. Inter-layer alignment tolerances required convergence . This convergent plate size becomes more demanding ambassador . Patterning processes are all generated at a temperature and humidity controlled environment. Exposure device at the same environment, the entire area in front of the figure and the figure is 0.0125mm need to maintain tolerance requires the use of a CCD camera before and after the completion of the layout of the place. After etching , drilling system using four internal shelves perforation. Piercing through the circuit board, the position accuracy remains 0.025mm, repeatable capacity 0.0125mm. Piercing needle is then inserted into the pin , the inner layer of the etching position , while the inner layer are bonded together . Perforation after using this etching method can fully guarantee the drilling and etching copper aligned , forming a solid ring design structure. However, with the user requirements in terms of PCB traces in a smaller area laid more lines, the fixed costs of the board remain unchanged, the required etching copper smaller size , requiring better interlayer copper bit . Fixtures and equipment must be capable of transmitting simultaneously conveying large size and heavy plate panels .
In addition to the drilling requirements of the plating layer of uniform thickness , the outer layer backplane designers generally on the copper surface uniformity has different requirements. Some designs etched in the outer few signal lines . On the other hand , faced with high data rate and impedance control line demand , the external layer is disposed near solid copper foil becomes very necessary to make use of the EMC shield . Since the user requires more layers, thus ensuring etching before bonding to the inner layer defect identification and isolation is very critical . To achieve the effective impedance of the backplane and reproducibly controlled etch line width, thickness and tolerances become critical indicators . In this case, the method can be used to ensure AOI etched copper pattern and design data match. Using the impedance model by the AOI to set linewidth tolerance , in order to determine and control the impedance of the line width variation sensitivity.
Traditionally , for reliability reasons, tend to use passive components on the backplane . However, to maintain the active plate fixed costs , BGA more active devices on the backplane design . Component mounting apparatus must not only be able to put a smaller size capacitors and resistors , but also must be able to operate the additional silicon package components . In addition , the backplane large sets of standardized equipment required to install the bed should be large and heavy backplanes for fine positional tolerance can also be shifted.
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