Interesting  - I note in the conclusions in the opening paragraph that they
state on the QFP failures:

" Failures in Sn-plated QFP components were probably due to batch related
solderability issues."

If you look at the "batch" you will find that this was:

4.3.5 QFP Electrical Testing
No electrical test failures occurred in any of the following combinations:
- Batch A (SAC solder with SnPb QFPs)
- Batch B (SnPbAg solder with SnPb QFPs)
- Batch D (SnPbAg solder with Sn QFPs)
- Batches E2, E3, E4 and E5 (Contaminated solder with Sn QFPs)
Electrical failures occurred only in the following batch between 1000 and
2000 thermal
cycles
- Batch E1, 4 failures (SAC solder with Sn QFPs)


Since in any experiment of this sort all other variables are removed, such
as component batch, reflow profile, solder batch et al to avoid skewing the
results I draw the conclusion by looking at this data that the "batch" they
are referring to is actually a tin finish component with SAC alloy
combination, and that anyone using this combo is in for an interesting time
unless he is right in the "sweet spot" of a reflow profile.


I find it extraordinary and very Interesting that they actually did not use
any 63/37 for the BGA trials (or any of the other testing given it's market
share historically) - I wonder why that would have been - anyone know??



John




John Burke

(408) 515 4992

-----Original Message-----
From: TechNet [ <mailto:[log in to unmask]> mailto:[log in to unmask]] On Behalf
Of N Burtt
Sent: Friday, January 05, 2007 8:01 AM
To: [log in to unmask]
Subject: Re: [TN] Qualification of ROHS Components with tin/lead Solder

THE NPL project report

"Measuring the reliability of electronics assemblies during the transition
period to lead-free soldering."

can be downloded free at

 <http://tinyurl.com/t6vlt> http://tinyurl.com/t6vlt

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