Steve: We also run an Electrovert Electra. We use Alpha's 871-25 OA flux,
similar to your 2331 which we have also used, applied by foam fluxing.
Looking at your photos it's hard to tell but the "Dross Particles" appear
more like solder webbing than dross and the "More Dross" does look like
dross.
I'm discounting a problem with the soldermask cure or board design because
you say it's happening with all your boards. However you may want to verify
soldermask cure as a sanity check.
1. My first guess is that you are drying out the flux on the board. The flux
no longer can act as a lubricant/thermal insulator and the solder and dross
stick to the board surface. Obviously insufficient flux deposition,
excessive preheat, slow conveyor speed can all contribute. Is it
re-occurring in a given band or area where there may be lack of flux or a
hot spot in the preheaters?
If item 1 is not the case consider the following:
2. Are you running the chipwave? This can be a large generator of dross. We
clean both the chip and Lambda wave pots of dross every two hours.
3. Is the overflow on the Lambda wave set correctly? If not you will not get
the proper overflow and dross will build in the wave.
4. How often do you remove and clean the chipwave and Lambda nozzles? We
remove and clean every 80 hrs of operation. These have a tendency to build
up dross which comes up thru the wave.
5. How often do you teardown the entire solderpot and pull everything out
for a complete cleaning? We do a complete teardown every 1000 hrs. You would
be amazed at how much dross and residue is built up inside the pot and it's
internal components.
Regards
Michael Barmuta
Staff Engineer
Fluke Corp.
Everett WA
425-446-6076
Regards
-----Original Message-----
From: Steve Gregory [mailto:[log in to unmask]]
Sent: Thursday, October 10, 2002 6:58 AM
To: [log in to unmask]
Subject: [TN] Dross particles sticking to soldermask...
Mornin' all,
I've got a problem here that's giving me a little headache. As you may know,
we got a new wave solder machine not too long ago, an Electrovert Electra.
For the past couple of weeks we've had a problem with dross particles
sticking to the soldermask. It's happening across all our boards, whether or
not we use an OA flux or RMA. Go to: http://www.stevezeva.homestead.com and
look at Dross Particles, and More Dross.
As you can see, it's not that bad, but it's irritating. The particles don't
want to come off without mechanically brushing the board either, and again
it doesn't matter if it's OA flux or RMA. If we run them through our
cleaners without brushing the boards, the particles will remain.
Our pot is clean, it's de-drossed every morning. We're using Kester 2331ZX
OA, and Alpha 16-125 RMA. It's being applied by a OptiFlux ultrasonic spray
fluxer.
The boards look great coming out of wave except for these random bits of
dross sticking to the mask. Solder joints look great, no dross in them at
all...just sticking to the mask.
Got me kind of puzzled...anybody ever have this happen to them?
Thanks!
-Steve Gregory-
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