Werner,
What I am trying to say is that issues of ground plane configuration will probably not lead to a reliability issue directly, unless they cause issues during reflow of the BGA. But if the ground pour is done using soldermask-defined pads, the soldermask-defined pads can lead to premature failure of the SJ. My understanding (gained from a direct question I asked you in your class) was that the soldermask can constrict the solder during CTE expansion and contraction. Did I not understand you correctly?
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Werner Engelmaier /*
Sent: Thursday, September 17, 2009 12:32 PM
To: [log in to unmask]
Subject: Re: [TN] fractured SJs due to soldermask compression
Hi Chris,
First, never heard of "fractured SJs due to soldermask compression during cyclic operation"—solder mask is much too soft and too thin; now, if you talk encapsulants that is a different story.
Second, "all of the other issues pale in the face of fractured SJs due to soldermask compression during cyclic operation"—even if it were an issue, a failure is a failure is a failure—'nough said.
Werner
-----Original Message-----
From: Chris Ball <[log in to unmask]>
To: [log in to unmask]
Sent: Thu, Sep 17, 2009 1:07 pm
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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