To clarify, the failures (ie. solder joint opens) seen during stress testing were occuring in the solder joint (on PBGAs, typically between the component and the joint; ie. the "top" of the solder column).

The failures at the pad/substrate or pad/component interface were ONLY occuring when we tried to remove the components to examine the amount of dye penetration (after applying and curing the dye penetrant).  It is this "how to" related to the dye penetration test I was intested in.

I have tried to access the Motorola site referenced and I get an error (site down??)  Any new address suggestions??

Thanks for the help.

Jim

> ----------
> From:         Jean-Paul Clech[SMTP:[log in to unmask]]
> Reply To:     TechNet E-Mail Forum.;[log in to unmask]
> Sent:         Thursday, January 14, 1999 7:38 AM
> To:   [log in to unmask]
> Subject:      Re: [TN] Dye Penetration Testing of BGA solder joints
>
> In a message dated 99-01-13 19:42:26 EST, you write:
> << 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.   >>
>
> James,
> Guidelines for the dye penetrant procedure are available in a Motorola ".pdf"
> file on BGA reliability . Last reference I had for this document was:
> http://www.mot-sps.com/solutions/wired/pbga/pbga.html
> (or do a search for "BGA reliability" at: http://mot2.indirect.com/cgi-
> bin/search)
>
> Failures at the interface between the BGA substrate and pads may and do occur
> under your test conditions. They are an indication of not enough adhesion /
> robustness in the pad area (even after a couple of joints have failed
> elsewhere). One possible solution (if you are still in the design phase) is to
> redesign with a larger copper area under the solder mask.
> As mentionned by Per, you can also test at higher temperature which will help
> shift the failures from the pad/substrate to the solder joint. It all depends
> on what your goal is for that test and what your strength requirements are.
>
> Jean-Paul
> _____________________________________________________
> Jean-Paul Clech
> EPSI Inc., P. O. Box 1522, Montclair, NJ 07042, USA
> tel: +1 (973)746-3796, fax: +1 (973)655-0815
> SMT / BGA / CSP Reliability Specialists
> home page: http://members.aol.com/Epsiinc1/index.html
>
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