We have a PCB with a detector that must be positioned at a particular height above a mounting surface. Our plastic parts are slightly undersized, so we must add some space (0.4 mm) between our PCB and the mounting surface in order to position the detector in the proper place.
The geometry is such that changing the board thickness doesn't solve the problem. We will eventually change our plastic mold to make up for the incorrect dimension, but we need to keep producing parts in the meanwhile.
We are looking for cheap and easy ways to create this space without making our assemblers fiddle around with shims, which can be dropped, misplaced, forgotten, etc.
I'm thinking that perhaps we can solder a washer-like part onto the PCB surface around the screw holes, if such a product exists. Or perhaps there is a way to recess the detector into the PCB somehow. Do such techniques or PCB surface shims exist? Can anyone recommend another method to tackle this problem?