We use Amtech 4300 and clean with DI water.
We have not had problems with cleaned boards and we could not induce
problems on cleaned boards.
While classified as L0, which might suggest that it could be used as a
"no-clean", we have found that it is not suitable for us as a "no-clean"
flux for rework applications in our customers service environment.
1. In its green state we were able to grow dendrites on test boards very
easily. We were able to grow dendrites in the residue from the wire core
solder. After seeing reflow temperatures we could not grow dendrites. So, as
a rework flux there are some issues.
2. In humid environments, during cold tests where the boards are subject to
frost, we found the residue became corrosive and it was again easy to grow
dendrites in the residue.
This is not an IPC test, I don't think there are any makers of flux that
would suggest the flux residue be exposed to a condensing environment.
So, is it real? It depends. It is not SMQ-92J. We found the residue of this
material to be much more stable in our tests.
Then there is the paste performance itself. 92J is really nice stuff on the
one hand, on the other we were not as happy with their Pb-Free materials.
Maybe they are getting better formulas.
We have been very happy with LF-4300 paste performance and consistency.
The upside on our line is one flux and one cleaning process for everything.
The downside is the residues do not behave like rosin based flux residue.
If they did, they would not wash off very easily would they?
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Robert Kondner
Sent: Wednesday, January 21, 2009 3:04 PM
To: [log in to unmask]
Subject: [TN] No Clean that can be removed?
Hi,
For the no clean fluxes that are removed with a saponifier, can you name a
couple or point me in the right direction?
I found that some no cleans had a wider temperature/time process window
than any of the OA fluxes but we never found anything that cleans Alpha
6100. Through hole and rework was forcing up to clean (water based) and
washing the no cleans cause problems.
The Alpha 6100 was a no clean and a stenciled board could sit for a few
days without a complete dry out of the paste. But the 6100 residue DOES NOT
CLEAN OFF in anything I found.
I would love to find a no clean with a wide temp window and no dry out,
like the Alpha 6100, but is also easy to remove. My previous understanding
was all water soluble fluxes were variations on OA flux which require
cleaning.
When I saw that 4300 I was very surprised. Is it for real?
Thanks,
Bob Kondner
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D.
Sent: Wednesday, January 21, 2009 2:47 PM
To: [log in to unmask]
Subject: Re: [TN] Strange Mask Appearance
There are many no-clean residues that are easily cleaned in a good machine
wash process with a saponifier added.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Kane, Joseph E (US
SSA)
Sent: Wednesday, January 21, 2009 1:42 PM
To: [log in to unmask]
Subject: Re: [TN] Strange Mask Appearance
Steve:
How can a no-clean flux be water-washable? If you leave residue on there,
any moisture encountered in service would attack it, dissolving and
spreading ionic contaminants, and causing corrosion, shorts, lifting of
coating.
And if it's something that you must clean anyway, why not use something more
active, with a wider process window?
Or what am I missing?
-Joe
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory
Sent: Wednesday, January 21, 2009 11:04 AM
To: [log in to unmask]
Subject: Re: [TN] Strange Mask Appearance
Hi Bill!
Yes, I would like your photos, thank-you very much.
To respond to Tan Geok Ang, the flux we used for the rework is Amtech 4300,
a solvent-based (ethanol), water washable no-clean. I know the picture looks
like the area around the screw heads is delaminated, but it is not. The
copper is relieved around the holes for the hardware in the inner planes and
that may contribute to the appearance that there's delamination.
Here's a photo of the same exact place on the same exact board after doing
nothing but heating the PCB up to 125 C. as I described in my earlier post.
http://stevezeva.homestead.com/files/Mask_Discoloration_After_Heating.jp
g
And the "before" photo:
http://stevezeva.homestead.com/files/Mask_Discoloration.jpg
Pretty dramatic change huh?
Steve
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of [log in to unmask]
Sent: Tuesday, January 20, 2009 1:59 PM
To: [log in to unmask]
Subject: Re: [TN] Strange Mask Appearance
Steve- I'm probably the culprit that put that report on TN long ago- and
again recently. Liquid solder masks often use fumed silica as
filler/thickener to keep it in place. This is often sold under the Cab-O-Sil
tradename.
Aggressive cleaning agents can dissolve off part of the under or un cured
solder mask polymer, exposing the while silica filler. When you heat the
undercured mask, it will soften and allow the filler to sink down into the
polymer, so the solder mask all looks green again.
Re the curing from wave solder, this may not work if you are working with a
UV cured mask. That's why it is important to monitor the output of UV lamps,
which not all shops do, thinking that UV lamps behave the same as
incandescent
lamps- which they don't.
Yes, the heat gun is a very inexpensive $0.05 test, quick, easy and requires
no instrumentation.
(Steve- I have some photos of the differences between one, two and three
passes under UV lamps to show the difference if you'd like them. If so, pls
give me a mailing address.)
Bill Kenyon
Global Centre Consulting
3336 Birmingham Drive
Fort Collins, CO 80526
Tel: 970.207.9586 Cell: 970.980.6373
**************A Good Credit Score is 700 or Above. See yours in just 2 easy
steps!
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