Hi Graham - yep, that's what I suspected. If they are following the
IPC/EIA JSTD-002C, they should be using a flux in accordance with
paragraph 3.2.2. which is a rosin type flux but has a very specific
recipe. The 002C committee changed the flux at Revision B and some folks
haven't noticed the change yet (hummm, if you are running a solderability
test, shouldn't you read the method!). The 002 committee made the flux
change based on an industry round robin test and the new flux formulation
provides better testing consistency and reproducibility. There's nothing
wrong with your soldering iron/RMA flux test - it would defined as a
soldering-ability test. The objective of the JSTD-002C test protocols is
to provide a common baseline measure of the solderability of a component
finish and your soldering iron test is the same measurement but includes
specific attributes reflective of your soldering process. In 002C
Appendix E, there is a listing of the test flux products that were
submitted to the 002 committee - see if the flux being used is on that
list.
Dave
[log in to unmask]
02/09/2009 05:39 AM
To
"TechNet E-Mail Forum" <[log in to unmask]>, <[log in to unmask]>
cc
Subject
RE: [TN] Part solderability
Hi David
When I talked with them on Friday they told me they were using a rosin
flux and following J-STD-002. I didn't ask brand.
The one thing I asked them to do is to put a soldering iron on a few
leads (one at a time) and reflow the dip coating. We have found that we
can dip tin these parts here with RMA flux, and have them look great,
but when we try to install them in CCAs it's a disaster. We found that
applying a soldering iron on the lead we would find the solder would
dewet. (Not sure dewet is the right term, but hopefully you see what I
mean) I'm sure my test is not J-STD-002 compliant, but it works for
me...
regards,
- Graham
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of David D. Hillman
Sent: Friday, February 06, 2009 8:03 PM
To: [log in to unmask]
Subject: Re: [TN] Part solderability
Hi Graham - Please find out what flux (i.e. product name: Kester XXX or
Alpha YYY or Indium ZZZ, etc.) the component fabricator used in his
test.
Also find out which solderability specification did they use
(IPC-JSTD-002C or MIL-STD-XXX) and which solderability test method did
they use (Method A or B or...). If you can get those facts, I can tell
you if they followed the specification requirements. My guess is that
they used an incorrect flux.
Dave Hillman
JSTD-002 specification Chairman
[log in to unmask]
Graham Collins <[log in to unmask]> Sent by: TechNet
<[log in to unmask]>
02/06/2009 08:12 AM
Please respond to
TechNet E-Mail Forum <[log in to unmask]>; Please respond to
[log in to unmask]
To
[log in to unmask]
cc
Subject
[TN] Part solderability
Hi guys.
A while back I rejected a bunch of parts due to non wetting when we went
to solder them.
The manufacturer has come back with a response to our guys, saying that
they did a steam aging test on them and they passed fine. He wants to
discuss it with us.
Obviously this is not good - they pass his test but I can't solder the
things. Which makes me suspect his test... but makes him suspect my
process. I don't know enough about steam aging tests to discuss this
well. Obviously I need to ask what kind of flux he is using, but
anything
else?
Our process is SnPb, we use RMA flux, and the wave soldering machine
runs
at 500F for the pot. This is on an assembly that we have happily built
for about 7 years, with the same manufacturer of part, and no process
changes that I can identify as significant. The part is what I would
call
marginally solderable, if we hand solder it and put a fair bit of heat
to
the lead we can get it to solder, but not well or easily. No previous
soldering issues with the part.
regards,
Graham Collins
Halifax Production Engineering
L-3 communications Electronic Systems
(902) 873-2000 ext. 6215
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