Hi Werner,
If class 1 is accepting 50% filling of through holes with solder and
class 3 is accepting full PTH, I hope you agree that the solder joints
strength are not the same?

What I wanted to clarify, is that with lead free process, beside the
known failures such whiskers, lifted pads etc., the DOA / short terms
failures are mostly bad solder joints (SMT and through holes) happened
because the small process window (PCB and components finish type / i.e
short storage / shelf life and hi peak temperature). 

I have seen lot of reliability tests evaluation of Lead free including
life cycles, talking about the difference between the alloys.  I didn't
see lot of tests evaluation dealing about the bad solder joints / low
yield happened because the small process window.

Best Regards
Reuven ROKAH 
e mail: [log in to unmask]


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Werner Engelmaier
Sent: Thursday, May 31, 2007 12:30 AM
To: [log in to unmask]
Subject: Re: [TN] RoHS compliant laptop with early failure

Hi Reuven,
Actually, it is not quality but inadequate or non-existant DfR [design
for 
Reliability]. Solder joints are subject to the same creep-fatigue
whether they 
are Class 1 or Class 3-the difference may be that the operational
environment 
may-may- be more severe for Class 3 product. But I have seen Class 1, or
more 
accurately Class 0 (Class minus 1?) [unsupported holes] in automotive 
under-the-hood environments.

Werner



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