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Finished my "investigation". Attached word doc, Steve, could you put it on your site?
Can anybody comment or give an advice?
Thanks,
Gaby
----- Original Message -----
From: Gabriela Bogdan
To: [log in to unmask] ; [log in to unmask]
Sent: Tuesday, January 29, 2008 8:49 PM
Subject: Re: [TN] Microvoids immersion silver
Decided to investigate further to qualify our vendors.
4BGA + 2 circuits and assembly.
Will cross section bare, after paste+reflow, after BGA assembly and also X-ray and dye and pry.
At least I will have fun.
Gaby
----- Original Message -----
From: [log in to unmask]
To: [log in to unmask] ; [log in to unmask]
Sent: Tuesday, January 29, 2008 8:35 PM
Subject: Re: [TN] Microvoids immersion silver
Hi Gaby,
I take it what you are seeing are 'champagne voids.'
Voids like these are 'encouraged by rough topography copper, excessive Ag thickness, some solder paste choices and rapid cool-down after reflow. But as Donald Cullen says in his comprehensive paper, it "requires the “Perfect Storm” of a rather contrived combination of parameters" to produce planar micro-voiding.
Well Gaby, now you know it—you are "Perfect." ;-)
Werner
**************
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