Hi Chris,

 

The normal board thickness tolerance is about +/-.007in. . Typical solder thickness as paste is about .006 in. nom. If the part floats to the top of the solder joint it will be something less than .006 or if the switch leads sink to the copper surface in the molten solder then it will be flush with the board surface… how much tolerance on the lead bend? Mounting? Brackets? Front panel? Etc… What if the board warps? I can see why you are looking for some sort of spec to refer to, however, there may not be one. I certainly am not aware of one that could help… perhaps someone else knows of something they could refer you to… but the only method I know is to fully look at ALL the possibilities and work through the math.

 

Best regards,

 

 

Hello All,

A mechanical designer is doing a tolerance stackup on one of our layouts and asked what we allow for the height of the solder between the board and the part. I babbled a while about how it's not that simple, then rooted around in IPC specs a while but couldn't find anything more definitive than "wetting is evident" for a value. I need to get back to him with a max value of some sort.

Does anyone out there have a value they plug in for stackup analysis?

We have SMT push-button switches and need to know where the top of the button will be relative to the surface of the PCB, min/max.

Thanks in Advance,
Chris
 


 

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