Steve,
Maybe the change in fillet appearance is just a matter properly optimizing
your fluxer parameters. Apply craft paper or thermal imaging paper to the
topside of a bare board and run it through the fluxer portion of your wave.
The flux will stain the paper giving you a good idea if your getting good
flow through and enough flux on your board.
Hope this helps some.
Scott
-----Original Message-----
From: Stephen R. Gregory [mailto:[log in to unmask]]
Sent: Monday, December 06, 1999 7:21 PM
To: [log in to unmask]
Subject: [TN] Spray Fluxers and Topside solder fillets...
Hi ya'll!
Well, I started wave-soldering with my new beast today, and promptly got
into
a head-butting contest with QA. We switched from foam fluxing to spray
fluxing, and there's problem with QA...(what's new? sheesh...)
The issue that they're having a problem with is the topside fillet
appearance. It does appear that the parts that have a clinch or parts that
have a stand-up/lock-in prep to the leads on them, may not have the
feathered, tapering fillet that rises above the surface of the PCB like we
saw with a foam fluxer, or with leads that drop-in straight to the board. In
my opinion, there's not a problem, and the fillets meet class-II, but here
it's so hard to teach a old dawg new tricks, as far as they're concerned;
"They don't look like they used to...". The fillets are perfectly fine on
the
bottomside, wetting 360-degrees, but on the top they may not fully taper
above the board and may be depressed a bit, but no more than 75%. and the
fillets are wetted to the barrel higher up than it has on the lead...so
under
a microscope, the fillet looks to taper down to the lead. The inspectors are
calling this non-wetting to the lead. I'm saying BS...the fillets are
acceptable. QA is trying to get me to re-wave the boards!...or have the
joints reworked by hand! Sheesh...does it ever end?
Anyways, have those of you that have had experience with spray fluxers ever
run into this issue? I'm using a Kester 2331-ZX (pretty active), but it's a
foam fluxer formula, but I'm still getting good coverage by spraying it. I
was told that I might need to get a spray formula if I didn't get good
coverage.
Any inputs?
-Steve Gregory-
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