This Tutorial demonstrates how to import PCB outlines from 3D CAD software to DesignSpark PCB
It is often the case that a board is designed for a known enclosure, for example one of the standard boxes available on the market or a box designed for a previous product. One way to create a PCB outline is to measure the enclosure and reproduce the dimensions in DSPCB. Alternatively dimensions can be taken from a datasheet (if one exists). The most reliable method though is to import dimensions from a 3D model of the enclosure, this is especially true for more complicated shapes. Simple shapes should not be underestimated though, it becomes apparent why when we imagine a produced prototype where mounting holes are several milimeters off and the board no longer fits the casing.
An example enclosure
For this tutorial we will import a PCB outline for the part BOCUBE IP67 enclosure, RS Part Number 7739461. It had been edited in a Mechanical CAD tool and a PCB outline was isolated and saved as AutoCAD DXF file
Importing the Board Outline file
In DSPCB select File>Import...
In the dialog browse to the DXF file with your PCB outline and click 'Open'
A DXF import dialog will appear. Ensure to select Import As 'Board', ensure units are consistent with your MCAD software (DXF format does not carry units) and the scale is set to '1' for most of the cases. You can save these settings with a Map File especially if your DXF file contains more layers
Note: if you are getting warinings or errors it means the DXF file you are trying to import is not suitable. Try to keep the import DXFs simple and you will get it working every time! Board outlines must be closed, non-intersecting (convex) shapes. For example they should not include segments that actually don't join up, DSPCB will not be able to convert these to a board shape.
Note 2: DesignSpark PCB will try to import DXF files as well as possible, you might get a warning similar to this: Warning (line 9298): Board Outlines must be closed and non-intersecting. Some shapes of these types have been created. These have been removed and replaced by open shapes on a non-electrical layer. If not possible to import as PCB outline, DSPCB will still import as shapes on all layers - which can be used as a template to manually draw a PCB outline on top
Checking & housekeeping
It is a good practice to verify the imported PCB outline dimensions against the original DXF file. Click on selected edges and view the bottom right corner od the screen:
We want to keep the Board shape (green) only for the true board outline so let's add pads for the mounting holes:
On the opposite sides of the holes there are some rectangular keepout areas for board supports, these can be drawn on the bottom silk layer to ensure no components go in these areas. The next step is to disable all layers from the Interaction Bar (shortcut F9) and delete the unwanted green PCB outline shapes. The end result is:
This can be exported to Mechanical CAD software with the IDF export from DesignSpark PCB (click here for instructions) to gain absolute confidence all important dimensions are in agreement with the enclosure
If you have any suggestions on how to improve this tutorial please drop us a comment below