日本語
I just got back some prototype PCBs from a PCB manufacturer and I noticed that they took out the solder mask between the pads of a QFN-40, 0.4mm pitch footprint.
I asked for the reason and they said their minimum solder mask bridge is 10mil (0,254mm). This constraint is not listed in their manufacturing capabilities, btw.
How important is it actually to have solder mask between the pads? For the prototypes and hand-soldering it didn't appear to be an issue, the PCB works as expected, would it be more critical for an actual PCBA run?
- Comments(1)
A****min
Jun 19.2019, 09:30:50
It is fairly usual.
They are assuming you are using a thin solder paste screen & having no mask between the pins will help the QFN sit hard against the board if there are any small placement misalignments.
So ................. use minimum solder paste to do the job to avoid shorted pins.
