Re: Dell Laptop component level repair
- From: Jeff Liebermann <jeffl@xxxxxxxxxx>
- Date: Tue, 08 Apr 2008 06:42:58 -0700
On Tue, 8 Apr 2008 05:59:50 -0400, "Michael Kennedy"
<Mikek400@xxxxxxxxxxxxxxxxxxx> wrote:
Thats a cool trick. Sounds better than blasting it with a heat gun and
blowing other componenents off the board. Have to try it on some junk boards
and see how it works.
Mike
<http://www.youtube.com/watch?v=eT_xuSI-gDw>
I found it really easy to overshoot. However, the failure is not
melting components or torching the board. It's having the BGA "drift"
or move sufficiently to short between connections. Some BGA chips are
also designed to have some air gap under the chip. If I over compress
this air gap to zero, I get more shorts caused by squeezing the solder
bumps into each other.
That's the problem with the C-clamp method. It localizes the heat,
but potentially squashes the solder bumps. The trick is apparently
not to over tighten the C-clamp. (I haven't tried this yet).
I did my best by first injecting some "no clean" liquid rosin flux
under the BGA before applying heat. The flux provided the necessary
oxidation protection, but also provided some protection against
shorting between pads.
Another trick I used it cut out the bottom of a somewhat larger
diameter tin can to use as a heat shield. I place it around the
burning cat food can. That fit inside the aluminum foil heat shield.
The problem wasn't burning components. It was melting the plastic
case because I was too lazy to remove ALL the plastic parts.
A few more tricks.
I had one success using a block of scrap aluminum on top of the chip
and a propane torch. It was a fairly small diameter BGA array, where
the cat food can was too large. Applying the heat about 1/2" above
the chip was very useful to prevent torching the board.
I put a heavy steel bolt or two as a weight at the bottom of the
burning can in order to keep it from moving around. Don't use a
painted can. Try to find a can with a flat bottom to maximize the
contact area surface. Use alcohol, not kerosene as some articles have
suggested, unless you enjoy the diesel stench.
I tried using some silicon grease, which had an interesting advantage.
When heated, whatever solvent is used to make it flow, gets
evaporated. The remaining silicon is more of a powder than a liquid,
which acts something like a glue. This kept the cat food can from
moving around. I cleaned off the mess afterwards with alcohol.
I'll try to remember to do a video next time.
--
Jeff Liebermann jeffl@xxxxxxxxxx
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
.
- References:
- Dell Laptop component level repair
- From: Mike S
- Re: Dell Laptop component level repair
- From: Jeff Liebermann
- Re: Dell Laptop component level repair
- From: Mike S
- Re: Dell Laptop component level repair
- From: Jeff Liebermann
- Re: Dell Laptop component level repair
- From: Michael Kennedy
- Dell Laptop component level repair
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