Hi,
I would like to have overlapping components. I’m adding test connector to my RF circuit. I would have three options to attach resistor or capacitor. I’m obviously getting lot of DRC errors, since I’m violating PAD to PAD clearance. I have created custom rule for courtyard overlap, but I’m not sure how to overcome PAD to PAD clearance issue?
You don’t . . . you live with/ignore it.
Or you just create your own custom footprint where no pads overlap.
But there are 3 discrete components and symbols in the schematic . . . they can’t all link to one footprint.
But only one of them can be assembled.
In such case I would do my symbol and footprint (both having 3 pins/pads).
I was thinking of making it like a 3 pin device with passive pins.
The decision if its a cap, a resistor and which of the pads are connected are made during soldering anyway, right?
It is not ideal to make new symbol and footprint, since it not possible to change default configuration in schematic. With current solution, I can select, which configuration is active with “do not populate”.
I understood that you just decide it at assemble time and need not to have that decision be visible at schematic and in PCB editor. I understood that you are doing a kind of prototype PCB to check something.
Looking at the clearance circles in your picture - you will have clearance problem even you will have only one resistor there.
I think there are a way (I didn’t tried it) to specify smaller clearance near fine pitch footprint and bigger clearance at the PCB rest. It could work here.
Yes, you have understood my goal correctly. There is another clearance problem with trace. I’m using coplanar waveguide and I would need 0.5mm clearance. 0402 capacitor is too small, so I have used custom rule zone over the component with 0.4mm clearance. This solution does not work with overlapping pads.
Is there any reason, apart from saving a bit of space, for not just using three separated footprints next to each other but not overlapping?
You probably have smaller clearance than 0.4mm between ‘combined’ pads so custom rule should specify smaller clearance. For my PCBs I use 0.2mm clearance.
When I had footprint with pitch 0.4mm (pad 0.22) I have specified clearance for PCB to 0.18 or 0.179.
Space is one thing, but overlapping as triangle would be more close to ideal RF circuit.
My design rule is 0.15mm minimum clearance.
