PCB best design method: four things that need to be taken into account when transferring PCB schematic to layout. All the examples mentioned in this article are developed using the Multisim design environment, but the same concepts apply when using different EDA tools.
Initial schematic transfer
Through the netlist file will be transferred to the layout of the layout of the environment in the course of the device will also transmit information, netlist, layout information and the initial line width settings.
Here are some recommended steps for the layout design phase:
1. set the grid and unit to the appropriate value. In order to achieve a more precise layout control of the components and the line, the device grid, the copper grid, the grid and the SMD grid can be designed as 1mil.
The 2 circuit board frame blank area and vias Shecheng required value. PCB manufacturers may have specific minimum or nominal recommended values for blind and buried holes.
3. according to the PCB manufacturer's ability to set the corresponding pad / hole parameters. Most PCB manufacturers are able to support drilling holes with a diameter of 10mil and a smaller hole diameter of 20mil.
4. design rules according to requirements.
5. set the custom shortcut keys for the common layer so that the layer can be switched quickly (and the hole is created) when wiring.
Update by labeling
Annotation is the process of transferring design changes from the schematic to the layout or from the layout to the schematic. Backward Annotation (layout to schematic) and forward annotation (schematic to layout) are key to maintaining accurate design. In order to protect the work that has been done, it is necessary to backup and archive the current version and layout files before any important forward or backward annotation steps.
Reset the device
Device re numbering is a function of the number of components on a PCB in a specified order. The reference mark should be sorted from top to bottom and left to right by PCB. This makes it easier to locate the device on the board during assembly, testing and error checking.
Processing the last minute device or netlist changes
The last moment of the PCB device or netlist change is undesirable, but sometimes because of device availability problems or the detection of the last minute design error and had to. If you need to change the components or netlist, it should be done in the schematic, and then forward to the layout of the tool. Here are some tips:
1. if you add a new device after the layout design begins, increase the resistance and the network. After being marked forward, the resistor will be displayed as an out of plane component in the outer frame of the circuit board, and at the same time the flight line indicates the connection network. The component is then moved to the outer frame of the circuit board and the wiring is normal.
2. the change of the back label and the reference label can work well, such as the re layout.
Positioning device by highlighting
In the PCB layout process, a way to navigate through a specific component or line in a schematic is to use the highlight selection function. This feature allows you to select an element or a line (or multiple objects), and then see where they are located in the schematic. This feature is especially useful in matching bypass capacitors and their corresponding IC connections. On the other hand, it is possible to locate a particular element or line in the layout while browsing the schematic.