Making two PCBs out of one project

Layout
1

I see there is an old thread about this, but I’m assuming there might have been some changes to how KiCad works (seeing that there have been multiple major version increases).

I would like to have an audio board and an auxiliary board. The audio board does the actual signal processing, the auxiliary board should feature the input jacks (probably not the jacks mounted on board), the footswitch, the DC input, the star ground and the LED circuitry. The connections between the boards should ideally be done with a ribbon cable or something of the sort. Is there a way to manage two different PCBs in one project? Or should I simply separate the two?

2

  1. Separate into two projects.

  2. Put in one board, but have a V-cut going between the sections so you can separate them. Might cost you just as much if the fab charges for the panelisation.

2 Likes
3

Probably not the perfect solution but you could lay them out on one board and put a row of closely packed small drill-holes.

I’ve seen real boards use this technique to create boards that snap in two with your hands.

I assume it’s a bit more cost effective to build/test them as one, and break later.

4

V-cut or mouse bites indeed!

5

Setting up the V-Cut machine probably takes quite a lot of time, and you have to pay for their time. If it’s for just a few PCB’s, you can consider just adding a few mm in between your PCB, and then cut it with a circular saw or other tools you have available at home.

Yes, there is that too.
The “cheap” PCB services rely on a pooling system, in which big panels are made with PCB’s from many customers. Small PCB’s are easier to handle by their nesting software then big PCB, and often you have to pay extra, or your order gets refused when the PCB fab sees there are two PCB’s in a single design. So check with your PCB manufacturer first.

6

V-cut have to go through whole panel. Do you order whole panel? If not than your PCB is probably on one panel with others having different dimensions - no way to have straight line through the panel. Or they make panel containing only your PCB - all panel processing costs are divided by 1 order.

But you have a right to have holes (different shapes) in your PCB. I use it often ordering PCB (single PCB) like I showed here:

7

The replies so far have concentrated entirely on the mechanical fabrication aspect. There is something else to consider: electrical connectivity, and the results you will get from the ERC.

Your two boards will be connected by ribbon cable, and thus there will presumably be two of whatever connector you are using, one for each end. You know this. The ERC does not know this, and will give a bunch of warnings and airwires.

You can of course ignore those errors. The risk is that you get into the habit of ignoring the airwires and thus miss any other errors, unrelated to the ribbon connectors (I have done this several times, resulting in bodge wires or board re-spins to fix it.

I have considered making a new component “pair of connectors” which has internal connections, but am not sure actually how to do that at the footprint level, so the two ends can be positioned separately.

8

I actually quite like the quick and dirty mouse bites approach to separate the two halves of the PCB. The only problem, at that point, is that the two halves should be somewhat comparable in dimensions (to make them easier to break off cleanly), while one of the two “halves” is only supposed to be, like, 3x3cm. So I’m not sure it would be easy to make it work. Not a big problem, anyway.