This command allows you to import and associate an IPC-D-356 and 356A format netlist into your design.
When importing IPC-D-356/A files, VisualCAM associates the net information for each layer in the input file to the conductive layers of the current design. Occasionally, you may encounter an IPC-D-356/A file that contains probe information for some of the inner layers. If you have a file of this type, you should make sure the appropriate layers are loaded in the current design. The layers will be associated in the same order they are encountered in the IPC-D-356/A file.
Since an IPC-D-356/A netlists contain information pertaining solely to pads and not traces, VisualCAM must generate an internal netlist prior to importing an IPC-D-356 netlist to ensure that your database contains a full and complete netlist after importing. While this may sound redundant, this prepares your data for an "automatic netlist comparison". This first step in the netlist comparison feature produces a report file detailing any differences between the internal and imported (external) netlist. When you run the Netlist Compare function, you are presented with a graphical comparison of the internal and external netlists, where VisualCAM highlights the discrepancies noted in the report. You will not have to "hunt and peck" through the report file and use the Query commands to find the issues.
If your goal is to perform a netlist comparison, see the Comparing Netlists tutorial for complete instructions. This topic will only cover the steps necessary for importing an IPC-D-356/A netlist.
Use File|Import|Import Wizard to import your Gerber data or File|Open to a previously-created VisualCAM .vcam file.
If you opened a .vcam file that already contains a netlist, select the File|Import|Netlist|IPC-D-356 command to import the external netlist. Then continue with step 9.
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If your database does not already contain a netlist, use the Setup|Layers command or the Navigator, make sure that each layer is "tagged" with the correct layer type. This is required so that the system understands what each layer is.
Remove any extraneous data on your electrical layers that are outside the perimeter of the board, such as title blocks, targets, crop marks, etc.
Tip: We recommend that any documentation for the board be done on a separate Drawing layer. If you wish to keep the data, placing it on a drawing layer assures it will not interfere with any processing, such as netlist extraction.
If you have any drawn pads in your database, select one of the Tools|Convert|Drawn Pads commands to convert them to flashes.
Use the Analysis|DRC/MRC command to make sure your layers are properly aligned. If any layers are misaligned, you can use the Edit|Align Layers command to align them.
Use the Tools|Pad Removal|Stacked command to remove any redundant pads.
Select the Tools|Netlist|Generate command, or use the Navigator shortcut command, to extract a netlist from your data.
Select the File|Import|Netlist|IPC-D-356 command, and select the desired netlist file from the Import IPC-D-356 dialog box.
After you import the netlist, a new External Net layer is created. Viewed by itself, this layer appears to contain no data. However, this layer contains the external netlist information, and links the external net points to the appropriate top/inner/bottom layer net test points. To view the points, turn on the associated top, bottom, and inner layers, and the external net layer. The net points are displayed in four ways for easy reference:
If net names are not provided in the IPC-D-356 file you imported, the system will automatically assign a unique net name as appropriate.
Below are examples of possible error message that can come from importing an IPC-D-356/A file, and what they mean:
No IPC data for location 2.8750, 3.7500 Layer:1
There is a pad on this layer that does not have any matching IPC information.
No Gerber data for location 1.5980, 4.3800 ID 45:() idx 43
There was an IPC-D-356 record for this location, but no Gerber data.
Gerber Net Re-assignment: VisualCAM net 78
Locations: 1.7980,0.8300 and 2.7980,4.2800
IPC nets 55:() 171:()
The IPC file has tried to associate the 2 nets, "55:()" and "171:()", to the VisualCAM net number 78
IPC Net Re-assignment: VisualCAM nets 123 250
Locations: 2.0980,1.0300 and 3.7980,4.3800
IPC net 78:()
The IPC file has tried to give the same net information "78:()" to the VisualCAM nets 123 and 250.