Craig,
Is there any organization that meets to discuss issues like this?
Thanks,
Steve
At 03:37 PM 6/8/2001 -0400, you wrote:
>Steve,
>
>Your complaint, if I read it correctly, is a classic one for all of those
>people that follow industry and military specifications regarding
>reliability, such as MIL-STD-217, and accelerated testing, such as JEDEC.
>The reality is that reliability does not work with a one-size-fits-all
>approach, but instead is sensitive to materials, geometry, and lifetime
>environmental loads.
>
>Many groups take a physics-of-failure approach to reliability, which allow
>them to accurately predict time-to-failure using a knowledge of wearout
>failure mechanisms, validated failure models, and acceleration factors that
>correleate results of accelerated tests to expected field behavior.
>
>Best Regards
>Craig
>
>
>-----Original Message-----
>From: TechNet [mailto:[log in to unmask]]On Behalf Of Steve Joy
>Sent: Tuesday, June 05, 2001 12:10 PM
>To: [log in to unmask]
>Subject: [TN] voids in BGA, but really reliability in general
>
>
>I am a little confused about BGA voids and reliability.
>
>How many field returns per year do we collectively see? My experience over
>the last several years was 0. Don't recall ever seeing one. But we all
>build to specs that mathematically predict some defects. So where are they?
>
>So it must meaqn the spec requirements are excessively tight. The
>characteristic life curves I developed showed that assemblies are
>incredibly robust. Of course, that is using the accepted acceleration
>factors.
>
>Which is my point. Why can't we use realistic (or better-experimentally
>defined) limits? I have run assemblies beyond 1K cycles (of -45C to 85C)
>with 70% voids and seen no failures. I am talking millions of joints in
>many package styles.
>
>Is there any industry group looking at this kind of problem?
>
>Steve
>
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