Chris: Whatever way you decide to define your pads, use the same type on the component and the board.
Non-solder mask defined pad advantages: � No point-of-stress concentration at edge mask and solder ball � No CTE mismatch at edge mask and solder ball � More space for routing traces between pads Non-solder mask disadvantages: � Smaller pads have poorer adhesion strength, performance in rework and multiple reflows, and heat dissipation Solder mask defined pad advantages: � Larger pads have better adhesion strength, performance in rework and multiple reflows, and heat dissipation Solder mask defined pad disadvantages: � Potential stress concentrations may start solder-joint cracking sooner � Less space to route traces between pads
Good luck on your new CAD
Dave F
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