When passing a PCB schematic to layout these six things must be mastered

When passing the PCB schematic to the layout design, there are many things to consider. To sum up, it is basically the following six things. Please check and fill in the gaps by yourself~

Device information, netlist, layout information, and initial trace width settings are also passed in the process of passing the schematic to the layout environment through the netlist file

1.

Here are some recommended steps to prepare for the layout design phase:

1) Set raster and units to suitable values. In order to achieve finer layout control over components and traces, the device grid, copper grid, via grid and SMD grid can be designed to be 1mil.

2) Set the blank area and vias of the circuit board frame to the required values. PCB manufacturers may have specific minimum or nominal recommendations for blind and buried via settings.

3) Set the corresponding pad/via parameters according to the capability of the PCB manufacturer. Most PCB manufacturers can support smaller vias with a drill diameter of 10mil and a pad diameter of 20mil.

4) Set design rules as required.

5) Set custom shortcut keys for commonly used layers to quickly switch layers (and create vias) when routing.

2.

Handling errors during schematic transfer

A common error during schematic transfer is a non-existent or incorrect package assignment.

It should be noted that if there is a device in the schematic that is not packaged, a warning message will pop up indicating that the virtual component cannot be exported. In this case, no default footprint information will be passed to the layout and the component will simply be removed from the layout.

A warning message indicating a mismatch is also generated during the delivery if the package is passed but does not correctly match a valid package shape.

Correct footprint assignments in the schematic, or create a valid footprint for any device. After correction, perform the forward dimensioning step to update and synchronize the design information.

3.

Update the design with callouts

Annotation is the process of passing design changes from schematic to layout or from layout to schematic. Back annotation (layout to schematic) and forward annotation (schematic to layout) are the keys to keeping designs accurate

To protect the work that has been done, a backup and archive of the current version of the schematic and layout files is required prior to any important forward or reverse annotation steps.

Don't try to make changes in both schematic and layout at the same time. Make changes to only one part of the design (either schematic or layout), then perform the correct annotation steps to synchronize the design data.

4.

Renumber the device

Component renumbering is a function of renumbering components on a PCB in a specific order.

Reference numbers should be ordered from top to bottom and left to right on the PCB.

This makes it easier to locate components on the board during assembly, test, and troubleshooting.

5.

Handling last-minute device or netlist changes

Last-minute PCB device or netlist changes are not desirable, but are sometimes necessary due to device availability issues or detection of last-minute design errors. If it is a component or netlist that needs to be changed, it should be done in the schematic and then forwarded to the layout tool through forward annotation.

Here are some tips:

If adding a new device (such as a pull-up resistor on an open-drain output) after the layout has been started, add resistors and nets to the design from the schematic. After forward labeling, the resistor will appear outside the board frame as an unlayout component, with flying leads indicating the connection to the net. Next move the components inside the board frame and perform normal routing.

Back callouts work well with reference number changes, such as back layout renumbering.

6.

Select the positioning device by highlighting

During the PCB layout process, one way to browse specific components or traces in the schematic is to use the 'highlight selection' feature. This feature allows you to select a component or a trace (or multiple objects) and see where they are in the schematic.

This feature is especially useful when matching bypass capacitors to their corresponding IC connections. Conversely, you can locate specific components or traces in the layout while browsing the schematic.