Making Slots in FreePCB

I have been using FreePCB to layout the boards I design. It is getting a little old and no longer has all the capabilities I desire. But it has all the pads I have designed over the years for hand building of SMT boards. I needed a pad for a component ( USB C connector with through hole pins) that requires slots for correct assembly. I have figured out a relatively easy way to design and produce such pads.

Making A Simple Plated Through Linear Slotted Pad in FreePCB.

You will use 2 surface mount pads on the top and bottom layers. And two through hole drilled pads. Call them holes one and two. I will assume you know or can figure out how to place the pads in relation to each other. Either manually or by using the set function included on each pad.

To get a proper CAM file you will have to connect all the pads together. First do this on a schematic that has all the pins connected, surface mount and through hole. That gives you a good net list.

After you lay down the component with slots in FreePCB and complete the wiring, on the top layer connect the surface mount pad to hole one. And then connect it to hole two. Lay down the "wires (traces)" as you do each connection.

Do the same for the bottom surface mount pad. Finally connect the two drilled pads together. I do that on the top and bottom layers. It may only be necessary on one layer. I haven't checked.

When editing the CAM drill file, the file you start with will look something like this. This file has eight holes for four slots ==>

.....
T02
X015624Y007852
X016215Y007852
X015624Y004447
X016215Y004447
X017093Y007852
X017408Y007852
X017093Y004447
X017408Y004447
T03
.....


The file with working slots will look like this ==>

.....
T02
X015624Y007852G85X016215Y007852
X015624Y004447G85X016215Y004447
X017093Y007852G85X017408Y007852
X017093Y004447G85X017408Y004447
T03
.....

Connecting the pads together with traces as suggested above eliminates DRC errors. Do a ratline recalculation before doing a Design Rule Check. I have checked this on Gerbv and another rendering program. They both show correct slots. As does OSH Park in their rendering of the completed board.

There is an online discussion about this method of making slots in FreePCB. You can find it here.


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