I think everybody will agree that soldermask-defined BGAs pads will always impact overall reliability for the under 30 mil dia ball BGAs...
So pour away, but don't design in soldermask-defined pads for your fine pitch BGAs...
Paul
Paul Edwards
Surface Art Engineering
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Vladimir Igoshev
Sent: Thursday, September 17, 2009 10:56 AM
To: [log in to unmask]
Subject: Re: [TN] fractured SJs due to soldermask compression
Chris,
What made you think compression?? Of solder mask has anything to do with the failure? Solder mask on SMD pads can act as a stress concentrator promoting crack formation, but I don't think it has anything to do with its compression or expansion.
Regards,
Vladimir
SENTEC
------Original Message------
From: Chris Ball
Sender: TechNet
To: [log in to unmask]
ReplyTo: TechNet E-Mail Forum
ReplyTo: [log in to unmask]
Sent: Sep 17, 2009 13:07
Subject: [TN] fractured SJs due to soldermask compression
Hello,
Starting a new branch here.
"All of the other issues pale in the face of fractured SJs due to
soldermask compression during cyclic operation."
Is this concern specifically for BGAs, or the same for any soldermask
defined pad, even including selectively waved through-hole (PbFree)?
Thanks,
-Chris
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