We did this for BGA pads, but have not thought about other types. So, this may or may not apply for those.
Pad defined by:||Advantages||Disadvantages Non-solder mask||No point-of-stress concentration at edge mask and solder ball||Smaller pads have poorer adhesion strength, performance in rework and multiple reflows, and heat dissipation ||No CTE mismatch at edge mask and solder ball|| ||More space for routing traces between pads|| Solder mask||Larger pads have better adhesion strength, performance in rework and multiple reflows, and heat dissipation||Potential stress concentrations may start solder-joint cracking sooner ||||Less space to route traces between pads
Finally, we'd suggest using the same type of pad on the board as are on the BGA interposer.
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