Need to make land pattern for smd through hole socket http://multimedia.3m.com/mws/mediawebse … 6E666666–
Is it ok to put dill holes that overlap the smd pad?
It can cause problems wicking solder away from the pads during reflow.
Looking at the recommended pattern, the holes are at the very edge of the pads.
Leon’s concern is valid, but in this case the holes would preferably not be plated, eliminating wicking.
When there are plated holes in a SMD pad (eg vias in the middle of QFN pads) I often reduce the problem by “tenting” the vias on the other side of the PCB. That is, you cover the holes with soldermask on the side of the PCB you don’t want to solder to. Some of the epoxy soldermask penetrates into the via holes, largely preventing any wicking of solder.
I’ve had problems with SMD connectors in the past - I think that pad sizes recommended by manufacturers tend to be too small, and can easily lead to mechanical failure if force is applied. We learned this the hard way with a batch of ~200 boards that experienced a lot of failures (~20%). It turns out that the copper pads were slightly lifting from the PCB, causing microscopic cracks in the copper.
We increased the pad size, and added vias to tie the pads to identical pads on the other side of the PCB. The soldermask opening was the same size as the manufacturer’s recommended pad. Since then, no failures, and soldering was easy enough with reflow / hot plate soldering techniques.
