I wish to add a question.
Did you experience this failure on perhaps mechanically stressed BGA's?
If so, the crack under the pads may be present before rework...
And why do you rework?
Shorts or opens?
Opens may be caused by lifted pads and connector break .
Are the failed pads locations random or on specific locatios?-(CORNERS??)
Gaby
----- Original Message -----
From: "Kane, Amol (349)" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Friday, August 25, 2006 2:29 PM
Subject: [TN] Copper Pad Peel Strength
> Dear Technetters,
> We are having instances where copper pads (Under BGAs) are being lifted
> off ENIG Boards almost too easily during rework. We use the same thermal
> profile on each board (for the same component removal) and only some show
> this phenomenon. Is there a test or standard to test the copper adhesion @
> incoming to see whether it's the fab (i.e. are the boards coming to us
> with poor copper adhesion strength to being with) or the process that's
> doing this. The board is heated upto 120 C when the component is reflowed
> for removal. Also, is there data to show the decrease in Cu adhesion
> strength with temp?
>
> Thanks,
>
> Amol Kane
> M.S (Industrial Eng.)
> Process Engineer
> Harvard Custom Manufacturing, Inc.
> 941 Route 38 Owego, NY 13827
> Phone: (607) 687-7669 x349
> [log in to unmask]
> www.harvardgrp.com
>
>
>
>
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