I am currently involved in Black Belt project which has focussed on
Wavesolder defects. We wave 0805 SMT assemblies and the majority of the
defects are shorts on SOIC's. Approximately 50% of the solder shorts are on
the back 2 pins, with the remaining shorts being distributed randomly
across the other pins. We do not use thief pads but have elongated the pad.
The current size is 0.5mm / 2mm.


Do we realy need thief pads because as we are seeing 50% of the solder
shorts distributed randomly across all other pins? and is it possible to
achieve sub 50 ppm (DPMO) for SOIC's?

Has anybody tried using a pad design that increments in length as they
progress to the back pins? I am looking to set up a test pcb that will
optimise the pad design, any suggestions on other pad shapes.

Any help on this problem would be greatly received.

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