I'll send angled view pics from our tin whisker boards. Like yours, low %age
of voids. Customer thinks voids are causing the electrical issues, I don't.
Will try to determine that the voids really are voids, and not dewettings.
If they are, then electrical problems can occur (e.g. skip plating). Voids
never use to cause electrical failures. Even as much as 50% voids solder
joints work and can have a normal life cycle.
/Inge
----- Original Message -----
From: "Paul Edwards" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Thursday, September 03, 2009 10:15 PM
Subject: Re: [TN] BGA Voids
Larry,
Sounds like the reflow profile is too hot on the bottom side...
Paul
Paul Edwards
Surface Art Engineering
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Larry Dzaugis
Sent: Thursday, September 03, 2009 9:54 AM
To: [log in to unmask]
Subject: [TN] BGA Voids
I have a 5-10% void on a bottom side BGA that grows to a 20-40% void when
the top side is assembled and reflowed.
Paste lead free OM338, profile is peak temp is 246 for 60 seconds.
Immersion tin board finish.
Why would the void expand on a second reflow? There are 22 BGA's on this
assembly. Only a few are growing voids, most voids seen are in the 5-10% or
less range.
Two parts are in the process of cross sectioning, to verify where the void
really is. Only have in line x-ray capablility, no angled views.
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