On Fri, 22 Apr 2011 21:09:14 -0700 (PDT), spamtrap1888
wrote:

On Apr 22, 4:46*pm, Jeff Liebermann wrote:

*At
first, I thought that someone had spilled some liquid into the laptop.
Nope, because all the corrosion is BETWEEN the PCB and the plastic,
with nothing on top of the plastic. *The plastic covering was totally
clean.

Liquid might have landed on the PCB but then wicked between the
plastic sheet and the PCB, where surface tension held it in place.

Nope. Look at the photos. Most of the rot is in isolated patches
with no fluid connections to the edge. Also, the "protective" plastic
sheet has some kind of glue smeared on one side, covering the entire
area. It will take considerable effort to remove it. I don't think
anything can creep underneath (including capillary action).

*There's no corrosion in the area that's NOT under the
"protective" covering, so it seems whatever did the damage, was
volatile.

The surface area of any trapped liquid is relatively tiny.

True. It also took years for the stuff to finally eat away the
copper. Mostly, it ate the areas around the PCB vias (holes), which
again points to something during manufacture. Probably a tiny amount.
Were it not for the "protective" plastic trapping the stuff, it would
have probably evaporated away.

The customer has 3 other identical laptops. *I just inspected them
(through the DVD slot), and found no corrosion. *

I'm not sure I'll be able to fix this one as the rotted traces in this
area are very tiny. *It's probably not worth the effort for a 9 year
old laptop.

The corrosion is not bridging the traces? Is the corrosion conductive?

I can't tell yet. It's definately eating away the traces because the
failure is lack of on/off and lack of charging (so far). Bridging
would cause other problems. Incidentally, I checked all the fuses and
power buses. They're fine.

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com
# http://www.LearnByDestroying.com AE6KS