Hello Techies
If I might add to this thread and the comments of both Gerard and Bev:
As a relatively new member of the IEC TC91 WG3, with responsibilities for
solderability test standards, and a manufacturer of such equipment, I have
been thrown in to the deep-end and been obliged to consider the rationale
for this test method. As I have learned, it was created as a quantitative,
repeatable test to measure the robustness of the surface finish under test.
As with any good measurement practice, and in order to give meaningful
results irrespective of the test location, it is necessary to remove as many
variables as possible. Hence the use of only 2 fluxes - SMNA that was used
for the good old rosin based processes - and Actiec 2 & 5 for "no-clean"
processes. Only 1 alloy is recommended: 60/40 Sn/Pb.
The globule test was introduced in order to deal with smaller SMD components
that would give more accurate results than dipping an 0402 into a bath.
Both techniques are somewhat more accurate than "eyeballing", surely?
Some folks have tried to introduce their own alloy and flux, some are even
planning to test with solder paste - yet these stray miles away from the
basic intent of good metrology.
As for the transition to lead-free processes, the jury is still out in
regard to the alloy, the flux and the test temperature. Soon there will be
revisions to both IPC J-STD002 and 003 that will be based upon a huge Round
Robin test programme involving some 20,000 tests. I think it fair to say
that Dip & Look did not yield very good Gage R&R, but Dave Hillman and the
team will no doubt elaborate on that in due course.
Hope this helps
--
Regards Graham Naisbitt
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>
> -----Original Message-----
> From: Luigi Cantagallo [mailto:[log in to unmask]]
> Sent: Wednesday, May 25, 2005 2:00 AM
> To: [log in to unmask]
> Subject: [TN] Wetting balance
>
>
> Hello Technetters,
>
> I have questions about wetting balance.
> We intend to use a wetting balance not to accept/reject supplied SMD's (Our
> SMD's are 1 to 5 years old) but to minimize the risk of solderability
> defects in production (Low volume, SnPb technology).
> So we don't apply J-STD-002D criterium but we try to find them to
> corroborate wetting balance and production results.
> On some tests (Wetting balance calibrated and in order, same type of flux,
> same alloy) on same component lots, we have not a perfect correspondence
> between wetting balance and visual inspections results in production (Vapor
> phase soldering). One of the case is "Good at the solderability test/Defect
> in production" and this one is the most risky.
> Somebody have experience with that kind of problem?
> What actions have you made ?
>
> Thanks for answers.
>
> Best regards,
>
> CANTAGALLO Luigi
>
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