Step one PCB design: PCB copy board's early work
1, using schematic design tool to draw schematics, and generates a corresponding netlist . Certainly , in some special cases , such as circuit boards is relatively simple, has had a netlist , etc. can not be schematic design , PCB design system directly into the PCB design system , you can directly access parts packaging , labor generate a netlist .
2 , manually change the network table is defined without pads on their feet and some other components fixed schematic connected to the network and it did not define any physical connection to ground or protect land. The inconsistency of some of the schematic and PCB footprint library Pin Pin name changed to the name of the device and PCB footprint library of consistent , especially , such as transistors .
PCB Design Step two: draw their own definition of non-standard package library device
Recommended that the devices themselves drawn into a library dedicated to establish their own PCB design files .
PCB Design Step three: Set PCB design environment and draw printed circuit board version of the middle frame with hollow etc.
1 , the first step into the PCB copy board system is set up after the PCB design environment , including setting the grid size and type , the cursor type , version layer parameters , routing parameters and so on. Most parameters can use the system default values, and these parameters after setting meet personal habits , do not go after the modification .
2 , the printed circuit board planned , primarily determines the frame board , including the size of circuit boards and the like. To be placed in a fixed place to put the pad hole of appropriate size . Available for 3mm screws 6.5 ~ 8mm outside diameter and 3.2 ~ 3.5mm diameter pads can be transferred from another board or PCB izard in the standard plate .
Note: Before drawing board to the frame , be sure to set the current layer Keep Out layer , which prohibits the wiring layer .
PCB design of the four steps : Open all use to copy board PCB library files , transferred netlist file and modify parts package
This step is a very important aspect , automatic routing PCB netlist is the soul , but also the impression of schematic design and design of the interface circuit boards , only after the network table is loaded to the circuit wiring version .
In the schematic design process , ERC check the package does not involve the issue of the part. Therefore , schematic design , the parts of the package may be forgotten , can be modified or supplemented in accordance with the design part of the package in the case of the introduction of the network table .
Of course , you can artificially generated netlist directly in the PCB, and specify the parts package.
PCB Design Step five: location arranged circuit board copy board part of the package, also known as the parts layout
Protel99 enables automatic layout, you can also manually layout. If automatic layout , run "Tools" below "Auto Place", use this command , you need to have enough patience. The key layout is the layout , most designers in the form of a manual layout. Use the mouse to select a component , press and hold the left mouse button , dragging the component to reach the destination , release the button , the element is fixed . Protel99 in layout adds some new tricks . New interactive layout options include automatic selection and automatic alignment. Use automatic selection method can quickly gather a similar package of components, and then rotate , expand and organize into groups , you can move to the desired position on the board . Upon completion of a simple layout , use automatic alignment neatly expand or tighten a package similar elements.
Tip: automatic selection , use Shift + X or Y and Ctrl + X or Y to expand and tighten selected X, Y direction component.
Note : the layout of parts , the mechanical structure should be from heat, electromagnetic interference, and other aspects to facilitate future wiring considered. Prior arrangement with the mechanical dimensions related devices and locking devices , and accounted for a large position devices and circuits core components , and then a small external components .
Six Steps PCB copy board : according to the situation and then make appropriate adjustments and then the entire device is locked
If the board space allows you can put some similar experiments on board wiring board area . For large board , should be more in the middle of fixing screw holes. Board has heavy devices or larger edge connectors and other devices should also force plus fixed screw holes , if there is a need to put in place a number of test pads , plus the best on the schematic . The hole is too small to change the pads too big , all fixed network definition screw holes pad to ground or protect land.
Put away look at the actual results with VIEW3D function , save.
Seven steps of PCB design : PCB board layout rules set to change
Routing rules are set for each specification cabling ( like using level, some of the rules of each group width , vias spacing, wiring topology , etc. , through the Menu at Design-Rules derived from the other board, and then import this board ) this step does not have to be set every time , according to personal habits , set it once .
Select Design-Rules generally need to re- set the following points:
1, the safety distance (Routing label Clearance Constraint)
It provides for the alignment must be maintained between the board via different networks , such as the distance from the pad . General board can be set to 0.254mm, compared with an empty board can be set to 0.3mm, more dense patch board can be set to 0.2-0.22mm, very few manufacturers of printing plate processing capacity in the 0.1-0.15mm, if it can levy you will be able to get them to agree to set this value. 0.1mm or less is absolutely prohibited.
2 , the level of alignment and orientation (Routing label Routing Layers)
Here can be set using the alignment layer and each of the main alignment direction . Please note that the patch panel with only a single top-level , single- line type only the bottom of the panel , but not in the power supply layer plywood set here ( you can Design-Layer Stack Manager , tap the top or bottom , with Add Plane add, double-click the left mouse button set point after the layer using Delete to delete ) , mechanical layer is not set here ( you can select to use a mechanical layer in Design-Mechanical Layer and choose whether depending on whether and displayed simultaneously in single display mode ) .
Layer 1 is generally used for mechanical drawing board sub border ;
Mechanical layer 3 is generally used for mechanical structures , such as the drawing board sub- block strip on ;
4 layer board machinery generally used for painting the ruler and comments, etc. , specific to their use in PCB Wizard to export a structure look PCAT
3 , through-hole shape (Routing label Routing Via Style)
It provides manual and automatic routing when automatically generated via the inner and outer diameter , were divided into minimum, maximum and preferred value , which is the most important choice for value , the same below .
4 , trace width (Routing label Width Constraint)
It specifies the width of the manual and automatic routing traces . Throughout the first palette ranges generally take 0.2-0.6mm, add some network or other groups (Net Class) line width settings, such as the ground , +5 volt power cord, AC power cord, power output cable and power pack and so on. Network group can be pre- defined in the Design-Netlist Manager in good ground is generally optional 1mm width , various power lines are generally optional 0.5-1mm width , line width and the current relationship between the printed board is about 1 per mm width allows amps of current , specific information can be found . When the preferred value is too large diameter makes SMD pads during automatic routing can not go on, it will automatically enter the SMD pads of some trace width reduced to the minimum width and between the pads , which is the entire Board width constraint board , it's the lowest priority , when that first meet the network cabling and network groups , such as the width constraints. Below is an example of
5 , the shape of the copper connection settings (Manufacturing label Polygon Connect Style)
Relief Connect recommended width of wires taken Conductor Width 0.3-0.5mm 4 wires 45 or 90 degrees.
The rest of the general availability of its original default values , but as the pitch wiring topologies , power level and shape matching network connections may need to set the length of other items .
Select Tools-Preferences, Interactive Routing Options bar at which the ( push encountered traces of other different network traces , Ignore Obstacle to pass through , Avoid Obstacle to block off ) election Push Obstacle mode and select the Automatically Remove ( automatic Remove excess traces ) . Defaults bar Track and Via , also can change it , generally do not have to move them.
Do not want to have placed in the area of traces FILL filling layers, such as lying beneath the feet and put the crystal radiator where the wiring layer , to put on the tin at the appropriate FILL in the Top or Bottom Solder.
Printed wiring rules set also one of the key circuit board design requires extensive practical experience.
Step Eight PCB design : printed circuit board wiring and manual adjustments automatic
1 , click the menu command Auto Route / Setup for automatic routing feature set
Select Add Testpoints addition to all items , especially select one of the Lock All Pre-Route option , Routing Grid optional 1mil so on. Automatic routing PROTEL before the start will give you a recommended value can not ignore it or to its recommended value , this value is smaller board more easily pass 100% of the cloth , but the greater difficulty and time spent wiring .
2 , click the menu command Auto Route / All start automatic routing
If the General can not be completely handmade cloth or UNDO proceed once ( do not use the Undo feature all the wiring , it will remove all pre-wired and free pads , vias ) after adjustments to the layout or routing rules , re- wiring . Upon completion do a DRC, wrong is corrected. Placement and routing process, if found wrong schematic diagram should be updated and network tables, manually change the network table ( with the first step ) , and then reinstall the network table cloth .
3 , the initial wiring manual adjustment
Need bold ground , power lines, power lines, bold output , a few lines around too much heavy fabric look, eliminate some unnecessary vias with VIEW3D function again look at the actual results . Optional manual adjustments Tools-Density Map view wiring density , red is the most dense, followed by yellow , green loose, press the End key on your keyboard to refresh the screen after reading . The red part of the general alignment should be adjusted to loose some , until it becomes yellow or green.
PCB Design Step Nine: switch to single display mode ( click the menu command Tools / Preferences, select the Display dialog bar Single Layer Mode)
The line drawing of each wiring layer neat and beautiful. Reference manual adjustment should always do DRC, because sometimes some lines will be disconnected and you may go a few lines from a good break in the middle of it , when the fast is completed can be printed out separately for each wiring layer to facilitate change lines when , during which must always check with the 3D density map display and functionality .
Finally cancel single display mode, save.
PCB Design Step ten: If the device needs to re- label can click the menu command Tools / Re-Annotate and choose a good direction , press the OK button.
And back to the schematic and select Tools-Back Annotate choosing the *. WAS newly generated file , press the OK button. Some of the schematic label should be re- drag to beautiful , all of it done and after the passage of DRC , drag and drop all the characters to the appropriate location silkscreen .
Try not to pay attention to the characters on the elements below or above the pad vias . For oversized characters can be appropriately reduced , DrillDrawing layer can demand put some coordinates (Place-Coordinate) and size ((Place-Dimension).
Last name put on printed board design version number, company name, date processing documents for the first time , the Indian board file name, file number and other information processing (see the figure shown in the fifth step ) . And available programs provided by third parties to add annotations , such as graphics and Chinese companies ROTEL99 BMP2PCB.EXE and macros potential PCB and PROTEL99SE special character input program package FONT.EXE so on.
Step eleven PCB Design : Teardrop fill vias and pads for all
Fill teardrop increase their fastness, but the line will become more difficult to see the board . Order by pressing the keyboard keys S and A (Select All ) , then select Tools-Teardrops, select the General tab of the first three , and select Add and Track mode, if you do not put the final document into the DOS version PROTEL format file the words can also be used in other modes , press the OK button. After the completion of the sequence by pressing X and A keys keyboard (all not selected ) . For patch and single panel must be added .
Twelve Steps PCB design : Place the copper area
The design rules in the temporary safe distance to 0.5-1mm and clear error flag , choose Place-Polygon Plane placing the copper ground wire networks in each wiring layer ( try to use octagonal rather than circular to wrap pads. eventually turn into a DOS file format , be sure to choose octagonal ) . The following figure is an example of setting the copper placed at the top :
After the setup is complete , press OK twist , the need to draw borders copper area , finally time to draw a side , you can simply press the right mouse button to start the copper . It defaults between your start and end points with a straight line is always connected to the circuit at higher frequencies selectable Grid Size larger than Track Width, follow the grid lines.
Place the rest of the copper wiring corresponding to several layers observed a large area on the copper layer is no place in the other place to put a clad layer vias , double-click at any point within the copper area and select one of laminates after direct point OK, then you can update this point Yes laminates . Several copper-clad laminates repeatedly several times until each layer are more full. The design rules where changed back to the original value of the safety distance .
Step Thirteen PCB design : The last to do it again DRC
Choose one Clearance Constraints Max / Min Width Constraints Short Circuit Constraints and Un-Routed Nets Constraints these items, press the button Run DRC , wrong is corrected. All save correctly .
Step fourteen PCB design : support for PROTEL99SE format (PCB4.0) processing factory in the document directory under watch case , export the file as a * PCB files ; support for PROTEL99 format (PCB3.0) processing factory , you can save the file as PCB 3.0 binaries do DRC. After passing exit without saving . In the case of viewing the document directory to export the file as a *. PCB files. Since a large part of the current manufacturers can do under DOS PROTEL AUTOTRAX painted board, so the following steps it is to produce a DOS version of the PCB document essential:
1 , the contents of all the mechanical layer changed to mechanical layer 1 , in the case of viewing the document directory , the network tables exported as *. NET file , open the PCB document in the watch case , the PCB export to PROTEL PCB 2.8 ASCII FILE format the *. PCB files.
2, with PROTEL FOR WINDOWS PCB 2.8 open PCB file, select Save As from the File menu and choose Autotrax format saved as a file can be opened under DOS .
3, with PROTEL AUTOTRAX DOS under open this file. Individual strings may want to re- drag or resize . All feet on decentralization chip components may produce case XY pad size interchangeable, adjust them one by one . After the big four columns XY pad SMD IC will be all interchangeable , can automatically adjust the half , one by one manually changed , please save at any time , this process is prone to human error. PROTEL DOS version but no UNDO function . If you previously chose cloth laminates and arc to wrap pad , so now all connected to the network have been basically manually delete one by one and modify these arcs are very tired , so we must be in front of recommendation used to wrap octagonal pads . Once these are completed, with the export front netlist for DRC Route of Separation Setup, the value should be smaller than the WINDOWS version , wrong is corrected , DRC until all through so far.
GERBER can also generate and drill files directly to the manufacturers choose File-CAM Manager Press Next> button out six options , Bom for the parts list table , DRC design rule checking reports , Gerber of Gerber files , NC Drill to drill hole document , Pick Place automatic pick and place files , Test Points test points for the report . Follow the prompts to select Gerber after a step down to do . Production capacity of some parameters related to the need to provide a printing plate manufacturer . Up until you press Finish . On the generated Gerber Output 1 Right click , select Insert NC Drill drill files added , and then choose Generate CAM Files Right generating real output file , you can export the Gerber files with CAM350 open and check. Note that the output power level is negative .
Fifteen steps of PCB design : send Email or copy disk to processing factories, indicate board material and thickness ( for general board , the thickness of 1.6mm, large plates available 2mm, RF microstrip boards typically 0.8-1mm around , and the dielectric constant of the board should be given other indicators ) , quantity, need special attention , such as the processing of the Department . Email issued a call to manufacturers after confirmation within two hours of receipt or not.
Produce and export the BOM file format after editing to conform to internal requirements .
The relevant part of the chassis frame machined screw hole connectors, etc. ( ie, the first part of the other unrelated select the Delete ) , export to metric dimensions of AutoCAD R14 DWG format files to mechanical designers .
Collate and print a variety of documents. Such as parts lists , device assembly drawings ( and should note on the printed scale) , installation and wiring instructions and so on.
