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Hi

For QFPs, the positional tolerance of the leads (of bent lead 
specification) is calculated based on the deviation of the Max Matl 
Condition (MMC) of the leads from the center line of the solder-pad.

Does anyone know how the positional tolerance for the solder balls are 
calculated ? We are trying to set up a specification for the solder-ball 
inspection. Is there a method specified under JEDEC, EIA, EIAJ, IPC ... etc 
that we can reference to ?


regards

Jeff-MH Tan
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