I've noticed similar 'goo' with repairs I have done on TV / VCR remotes. I
always use IPA. However, the outer touch surface of the elastomer pads
usually show a brown 'goo' on the wipe or swab after cleaning, and the
internal surfaces leave a black 'goo' on the wipe or swab. I'm thinking the
elastomer pads are printed with a carbon ink to make the connection when
pressed against the interleaved 'pitch fork' pads on the board. The plated
pads on the board usually leave a brown 'goo' on the wipe or swab. After a
thorough cleaning, I usually leave the pieces on a paper towel for a couple
of hours to dry, then reassemble the components. I've even performed this
routine on a remote that was dropped into a fish tank! Still works good to
this day! I have also noticed that repairs done on units that reside in
smokers dwellings reveal a darker brown 'goo'. I've never noticed any type
of sealing compound, such as dielectric silicone grease or glue on hand held
units taken apart for repair.
If you have access to one, a SEM should reveal the chemistry behind the
brown 'goo' phenomenon. Or maybe you could send a 'goo' sample to your local
CSI lab to see if there is any DNA within it. ???
My favorite tool is the Victorinox 'Swiss Champ', don't know what I would do
without it, except carry around a small tool box!
Dave Simonik
Sanmina-SCI
Owego NY Division
-----Original Message-----
From: Blair K. Hogg [mailto:[log in to unmask]]
Sent: Friday, November 05, 2004 9:42 AM
To: [log in to unmask]
Subject: A Friday question
Greetings 'netters:
Had the occasion last night to perform surgery on a cordless telephone, the
buttons had become dysfunctional rendering the phone basically unusable.
I've done this on other phones before, and each time have found that the
elastomer switch panel and printed circuit board have become coated with
some kind of "goo".
I believe that this "goo" is the accumulation of skin oils which somehow
migrate into the phone and get under the elastomer, but have thought that
perhaps some manufacturers intentionally put some kind of compound on the
elastomer for some reason (sealing?). I'm leaning toward the skin oil
explanation, since we make products here with elastomer switch panels and
have never used any sealing compound during assembly. Anyone else out there
doing this kind of assembly and do you put anything on the elastomer during
assembly?
Also, in the past I've cleaned up the elastomer with drug store IPA (91%),
but here I was last night working in the kitchen with a Swiss army knife
(one with all the tools on it) and there next to me was the sink and a
bottle of Palmolive detergent. Well, I though, aqueous wash, and went at it.
It worked pretty well, but after reassembly the left over moisture began
condensing on the window and it was hard to see the display. I'm sure this
will clear up after a while, though.
So what do you cleaning gurus think is the best way to remove the "goo",
whatever it is? IPA or Palmolive? Is Palmolive a saponifier or a surfactant,
or both?
Happy Friday,
Blair
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