Hi Jim,

We did dye penetration testing of plastic BGAs a few years ago (see
"Reliability of Ball Grid Array Packages in an Automotive Environment",
Proc. Surface Mount International, 1997, pp. 85-92). The trick is to let
the solder creep when you remove the package. We achieved that by gluing
a steel hook on top of the package with a high-strength epoxy (make sure
that the surface is clean before you apply the glue) and a weight of 10
kg was then attached to the hook, applying a vertical pull force. With
time, sometimes for several hours, and in some cases with a little help
from elevating the temperature to approximately 85 degree C, all BGAs
could be removed in a consistent way.

Hope this will help you. Please contact me if you want to discuss it
further.

Per-Erik Tegehall
IVF
SWEDEN

Phone: +46 31 706 61 48
Fax: +46 31 27 61 30
Email: [log in to unmask]


> ----------
>
> As part of our BGA reliability testing we would like to perform dye
> penetration testing of some of our BGA solder joints (typically after
> they've seen vibration and/or thermal stress tests.)
>
> I've seen references to dye penetration tests being done (and even
> photo's of joints); what I am looking for is a reference to a person
> that actually has done this.  We've tried and frankly are having
> difficulties (with plastic BGAs) "popping off" the BGA to look at the
> solder joint.  Typically, we tend to fail at the interface between the
> substrate (sometimes the PWB, sometimes the interposer) and the pad
> rather than in the solder joint.  Now this happens EVEN on parts that
> have gone through extensive life testing (thermal cycle/shock) and
> gone "open".  We've cross sectioned some parts and the solder joints
> (many of them) are in fact cracked.
>
> I have a feeling there is a "technique" to this and I want to talk
> first hand with a person that's "got the touch".
>
> Thanks for your assistance.
>
> --------------------------------------------------------
> Jim Maguire
> Boeing Phantom Works
> E/E M&P
> Phone (253)657-9063
> Fax (253)657-8903
> email:  [log in to unmask]
> ---------------------------------------------------------
> ---------------------------------------------------------
> Jim Maguire
> Boeing Phantom Works
> E/E M&P
> (253)657-9063
> email:  [log in to unmask]
> ---------------------------------------------------------
>
>

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