Talking creepy things, has anyone of you performed practical tests to 
confirm theoretical calculations on life of BGA boards?  We sell products 
with life expectancy like 20  years minimum.  Theory is one thing, but what 
will really happen after five years, ten years, fifteen year...? Allright, 
so many design variants, so many factors and difficulties to jugdge the 
result. If I put the question this way: do any of you fear that your BGA 
board will be failure reported long before the guaranteed TTF?  ......Ja. 
ja, I know. Noone will let the whole world know.  My question suits better 
in the waste bin. We have done ver 100,000 tempcycles on BGA boards, and I 
hoped that someone (mad) had done same.
/Inge

--------------------------------------------------
From: "Roger Mack" <[log in to unmask]>
Sent: den 14 April 2010 07:23
To: <[log in to unmask]>
Subject: [TN] solder creep charts

> Does anyone have a detailed solder creep graph (shear stress N/mm² vs.
> time to rupture) for tin lead solder?
> I have been using Figure 4.35 from Klein Wassink's Soldering in
> Electronics. This graph starts at a shear stress of 1.
> We have run a ProE computer model that shows a shear stress value of
> 0.6N/mm² on the connector pins of two boards that are mounted together. We
> have placed some samples to bake at the maximum service condition
> temperature to validate the computer model is realistic. It does not take
> much of an extrapolation error on a small text book graph to be off by an
> order of magnitude.
>
>
>
> Roger Mack  P.Eng.
> Manufacturing Specialist
> Parker Hannifin Electronic Controls
> Electronic Controls Division
> 1305 Clarence Avenue
> Winnipeg, MB  R3T 1T4 Canada
> direct 204 453 3339 x373
> [log in to unmask]
> www.parker.com/ecd
>
>
>
>
>
> PLEASE NOTE: The preceding information may be confidential or
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