Hi James, IPC LF Listservers,

I know this is for Werner, yet I wanted to add a point.

<----From you note---->
>So, at what point can we believe the evidence of our eyes?


Back a LONG long time ago I was a lowly high volume soldering engineer and
was given the task of comparing the first large scale introduction of OSP
(Entek) in comparison to some other PCB finishes. The OSP guys (which I
liked and still do) tried as hard as they could removing oxides and
tinkering with their process yet on a visual level the solderability of OSP
didn't compare with the finishes of the day for the componetry, fluxes.
OSP "eyes viewed" solderability was erratic since sometimes it was as good
yet not always, nor consistent.

I was overruled by management and the process was approved because of
company and industry rules of what is a minimially good in specifications
for solder joints. Lands, leads, and other stuff did not pass visual
inspection; as good as, with SnPb yet were specification acceptable.

So when you say "our eyes" please don't say that SAC looks as good as SnPb
in all situations since it DOES NOT look as good nor wet as good or as
completely. It also sometimes has a very rough bumpy texture which in SnPb
would be indicative of contaminants, outgassing, etc.


Yours in Engineering, Dave
Y i Engr, MA/NY DDave

>The IDEALS project arrived at a statement pretty much along the lines
>you criticize below back in 1998/9 (we said "functionally equivalent" if
>memory serves), and many have since.  I agree that caveats are required
>to circumscribe statements on "reliability", but clearly it is the case
>that practical experiments on real PCBs do show (and here I search for a
>phrase) a broad correspondence in behaviour between SnPb and Pb-free.
>
>So, at what point can we believe the evidence of our eyes?  What will
>define, say in IPC-7095 terms, the believable test?

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