Did BGA (PWB?) substrate warp, causing the non-contacts?
Did the motherboard PWB that the BGA is reflowed to warp?

 -Michael Alderete
Aerojet

 ----------
From:  rob starr[SMTP:[log in to unmask]]
Sent:  Wednesday, July 09, 1997 4:13 PM
To:  ipc
Subject:  BGA Question

Hello there, an engineer friend of mine suggested asking this question to
this address for advise.

I have some separation of BGA contact from PCBs,  the pad size is 20 mil,
the balls are 30 mil, the pitch is 50 mils.  the board is Fr-4 , 0.062 ".   
4
layer

is this configuration acceptable or what changes to the pad could be made
to improve solderability?


thanks in advance,

 [log in to unmask]

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