I would like to take an informal survey of BGA pad design styles.


1.   Are you using soldermask defined pads or pads that are clear of 
mask? (by soldermask defined pads I mean, the copper land is larger 
than the soldermask opening allowing the soldermask to define the BGA 
attachment site)

2. If you use Soldermask defined pads do you allow the soldermask to 
fall off the pad (misregistration)?   If not how much registration do 
you allow for to keep the soldermask on the pad?

3.  Do you experience problems with mask lifting during rework?


Thanks for the help..looking forward to the discussion.



Douglas Jeffery
Electrotek,Inc.







  

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