Prototype PCB Assembly Advertising Machine Motherboard
PCB design process is divided into six steps: table input, rule setting, component layout, lining, inspection, review and output.
1.1 network table input
There are two ways to input network table. One is to use OLE PowerPCB Connection function of PowerLogic. Select Send Netlist and OLE application function to keep the schematic diagram and PCB diagram consistent at any time and minimize the possibility of error.
Another method is to load the network table directly in PowerPCB, select file->Import, and input the network table generated by the schematic diagram.
1.2 rule setting
If the PCB design rules have been set up in the schematic design stage, you do not need to set these rules anymore, because the design rules have been entered into the PowerPCB along with the network table when the network table is entered.If the design rules are modified, the schematic diagram must be synchronized to ensure that the schematic diagram is consistent with the PCB. Except for the design rules and Layer definitions, there are other rules that need to be set up, such as the Pad Stacks that need to change the size of the standard stack. If the designer creates a new solder pad or hole, be sure to add Layer 25.
PCB design rules, layer definition, through hole setting, CAM output setting have been made into the Default startup file, the name is default.stp, after the network table input, according to the actual situation of the design, the power network and ground are allocated to the power layer and ground layer, and other advanced rules are set.In PowerLogic, the Rules From PCB function of OLEPowerPCB Connection is used to update the rule settings in the schematic diagram to ensure that the schematic diagram and the rules of the PCB diagram are consistent.
1.3 component layout
After the input of the grid table, all the components will be placed at the zero point of the working area and overlapped together. The next step is to separate these components and arrange them in order according to some rules, that is, the components layout of PowerPCB provides two methods, manual layout and automatic layout.
1.3.1 manual layout
1. Draw Board Outline by using the structure size of printed circuit board.
2. Disperse Components to make them be arranged around the edge of circuit board.
3. Move and rotate the components one by one, place them within the pcb edge, and arrange them in order based on certain rules.
1.3.2 automatic layout
PowerPCB provides automatic layout and automatic local cluster layout, but for most designers, the effect is not ideal.It is not recommended.
1.3.3 matters needing attention
A. The first principle of layout is to ensure the distribution rate of lining, pay attention to the connection of flying lines when moving devices, and put devices connected together.
B. Digital devices and simulator components should be separated and kept away from each other as far as possible.
C. Decoupling capacitance should be as close as possible to the VCC of device.
D. Future welding should be considered when placing devices, not too dense.
E. Use Array and Union functions provided by the software to improve the efficiency of layout.