PCB design flow is divided into six steps: netlist input, rule setting, component layout, wiring, inspection, review, and output.
2.1 Netlist input
There are two ways to enter the netlist. One is to use PowerLogic’s OLE PowerPCB Connection function.
Send Netlist, applying OLE function, can keep the schematic and PCB diagram consistent at all times, and minimize the possibility of error.
Another method is to load the netlist directly into the PowerPCB, select File->Import, and enter the netlist generated by the schematic into
2.2 Rule settings
If you have already set the PCB design rules in the schematic design phase, you don’t have to set it up.
These rules, because when entering the netlist, the design rules have been entered into the PowerPCB with the netlist. If the design rules are modified
Then, the schematic must be synchronized to ensure that the schematic and the PCB are consistent. In addition to the design rules and layer definitions, there are some rules.
Need to set up, such as Pad Stacks, you need to modify the size of the standard via. If the designer has created a new pad or
The hole must add Layer 25.
PCB design rules, layer definitions, via settings, and CAM output settings have been created as default startup files with the name
Default.stp, after the netlist input comes in, according to the actual situation of the design, the power network and ground are assigned to the power layer and
Strata, and set other advanced rules. After all the rules are set, in PowerLogic, use OLE
Rules From PCB function of PowerPCB Connection, update the rule settings in the schematic, guarantee the schematic and PCB
The rules of the graph are consistent.
2.3 Component layout
After the netlist is input, all the components will be placed at the zero points of the work area, overlapping, the next step is to put this
These components are separated and placed neatly according to some rules, that is, component layout. PowerPCB provides two methods, hand cloth
Bureau and automatic layout. 2.3.1 Manual layout
- The structural dimensions of the tool printed board are drawn with the board outline.
- Disperse the components (Disperse Components) and the components will be arranged around the edge of the board.
- Move the components one by one, rotate them, place them inside the edge of the board, and arrange them neatly according to certain rules.
2.3.2 Automatic layout
PowerPCB provides automatic layout and automatic local cluster layout, but for most designs, the results are not ideal.
Not recommended. 2.3.3 Notes
- The first principle of the layout is to ensure the wiring rate of the wiring, pay attention to the connection of the flying line when moving the device, and the device with the connection relationship
Put together pieces
- Separate digital and analog devices and keep them as far away as possible
- Decoupling capacitors as close as possible to the VCC of the device
- Consider the future soldering when placing the device, not too dense
- Increase the efficiency of the layout by using the Array and Union functions provided by the software.
There are also two ways to route, manual routing and automatic routing. PowerPCB provides a very powerful manual routing function.
Including automatic push, online design rule checking (DRC), automatic routing is performed by Spectra’s routing engine, usually these two
The method used together, the common steps are manual – automatic – manual.
2.4.1 Manual wiring
- Before auto-routing, first manually lay some important networks, such as high-frequency clocks, main power supplies, etc. These networks are often
There are special requirements for trace distance, line width, line spacing, shielding, etc. Other special packages, such as BGA, are very easy to route.
Difficult to have rules, but also use manual wiring.
- After the automatic wiring, the wiring of the PCB should be adjusted by manual wiring.
2.4.2 Automatic wiring
After the manual routing is over, the remaining network is handed over to the autorouter from the cloth. Select Tools->SPECCTRA to start
The interface of the Spectra router, set the DO file, press Continue to start the automatic routing of the Spectra router.
If the cloth pass rate is 100 after the bundle, then you can manually adjust the wiring; if less than 100, the layout or manual
There is a problem with the wiring, you need to adjust the layout or manual wiring until all the wiring.
- Power cord and ground wire should be as thick as possible
- Decoupling capacitors should be directly connected to VCC
- When setting the Spectra DO file, first add the Protect all wires command to protect the manual cloth from being automatically
Wiring the cloth
- If there is a hybrid power layer, the layer should be defined as Split/mixed Plane, which is divided and laid out before wiring.
After the line, use Pour Manager’s Plane Connect for copper cladding
- Set all device pins to the thermal pad mode by setting Filter to Pins, selecting all pins, and repairing
Change the attribute and tick the Thermal option.
- Open the DRC option during manual routing, using Dynamic Route (Dynamic Route)
Checked items have Clearance, Connectivity, and High Speed.
And the power layer (Plane), these items can be selected by Tools->Verify Design. If the high-speed gauge is set
Then, you must check, otherwise, you can skip this item. Check for errors, you must modify the layout and wiring.
Some errors can be ignored, for example, some of the connectors’ outlines are placed outside the board frame, and the spacing is checked out.
Wrong; after each modification of the traces and vias, the copper must be re-applied once.
Review according to the “PCB checklist”, including design rules, layer definition, line width, spacing, pads, via settings;
It is also important to review the rationality of the device layout, the routing of the power supply and ground network, and the routing and shielding of the high-speed clock network.
Coupling capacitor placement and connection, etc.. If the review fails, the designer must modify the layout and wiring. After passing the test, the reviewer and the design
2.7 Design output
The PCB design can be output to a printer or output illuminating file. The printer can print the PCB layered for designers and complexes.
Check the inspection; the light painting file is handed over to the manufacturer of the board to produce the printed board. The output of the light painting file is very important, which is related to this design.
The success or failure of the meter, the following will focus on the notes on the output of the light painting file.
- The layers that need to be output have a wiring layer (including a top layer, bottom layer, intermediate wiring layer), and power layer (including VCC layer and GND).
Layer), silkscreen layer (including top screen printing, bottom screen printing), solder mask (including top layer solder mask and bottom solder mask), in addition
To generate a drilling file (NC Drill)
- If the power layer is set to Split/Mixed, then select Routing in the Document item of the Add Document window.
And before each output of the lithographic file, the PCB diagram should be copper-clad using Pour Manager’s Plane Connect;
If it is set to CAM Plane, select Plane. When setting the Layer item, add Layer25, in Layer25.
Select Pads and Vias in the layer. In the Device Settings window (press Device Setup), change the value of Aperture to 199.
- Select the Board Outline when setting the Layer for each layer.
- When setting the layer of the silkscreen layer, do not select Part Type, select the top layer (bottom layer) and the silkscreen layer’s Outline,
- When setting the Layer of the solder mask, selecting the via hole means that no solder mask is added on the via hole, and the via hole is not selected to indicate the home solder mask, depending on the specific situation.
- When creating a drilling file, use the default settings of PowerPCB, do not make any changes.
- After all the lithography files are output, open and print with CAM350, and check by the designer and reviewer according to the “PCB checklist”.