14 Nov
2005
14 Nov
'05
5:32 p.m.
From: "Allison" <ajp166 at
bellatlantic.net>
>
>Subject: removing parts from PCBs
> From: compoobah at valleyimplants.com
> Date: Fri, 11 Nov 2005 20:31:31 -0600
> To: <cctalk at classiccmp.org>
>
>I've seen several references to using torches to remove DIPs from PCBs. Are
there any specific things to keep in mind to avoid heat damage? Are you talking
propane plumber's blowtorches?
Dang, thats one long line!
Yes, work fast.
Myself I torch the bottom and use a spring loaded chip extractor.
That and a pliers or tiny screwdriver to straighten any bent
pins keeping it in the board.
Success rate to date is 99% (board was known bad before salvage).
Allison
Hi
I've used peanut oil and a fry pan. Then wash the
parts in detergent to remove the oil. You need to wear
gloves and goggles as safety gear. Hot peanut oil
in your eye is not something I'd like to even think about.
Make sure that the assembler didn't bend the corner leads
of the ICs. If they did, you'll need to straighten them
before the oil, using a soldering iron.
It just seems to me that the oil method is a little more
controlled than a torch.
Dwight
14 Nov
14 Nov
6:01 p.m.
On 11/14/2005 at 9:32 AM Dwight K. Elvey wrote:
I've used peanut oil and a fry pan. Then wash the
parts in detergent to remove the oil. You need to wear
gloves and goggles as safety gear. Hot peanut oil
in your eye is not something I'd like to even think about.
Make sure that the assembler didn't bend the corner leads
of the ICs. If they did, you'll need to straighten them
before the oil, using a soldering iron.
It just seems to me that the oil method is a little more
controlled than a torch.
That's downright scary--oil fires are nasty. And burns from oil that hot
(I've had them from cooking) take a long time to heal.
I've heard plenty about the big 30-quart propane-fired turkey fryers
catching fire. I'm not so sure that I'd like to try your method, although
it sounds interesting.
Is synthetic automotive oil flammable at desoldering temperatures?
When I'm removing the bottom bow cap of a large tuba, I simply put the
entire bow on an old propane barbeque grill that has the bottom rack lined
with firebrick. No direct flame and the result is that in a few minutes of
heating the big assembly falls apart. I may try the same setup to desolder
an old board to see if it fares any better than a torch.
Cheers,
Chuck
6:17 p.m.
Chuck Guzis wrote:
On 11/14/2005 at 9:32 AM Dwight K. Elvey wrote:
True, but it is no less risky than normal cooking with oil - plus it'd
give a much more even heat than a torch. Might give that a try sometime.
Cooking oil is probably cheaper than torch gas too :)
My only caution would be that gold/ceramic ICs tend to have markings
printed on with an ink that detergent will remove quite nicely (made
that mistake once when cleaning a PCB, won't be doing it again :) Other
components seem to survive such cleanings quite happily though.
cheers
Jules
I've used peanut oil and a fry pan. Then wash
the
parts in detergent to remove the oil. You need to wear
gloves and goggles as safety gear. Hot peanut oil
in your eye is not something I'd like to even think about.
Make sure that the assembler didn't bend the corner leads
of the ICs. If they did, you'll need to straighten them
before the oil, using a soldering iron.
It just seems to me that the oil method is a little more
controlled than a torch.
That's downright scary--oil fires are nasty. And burns from oil that hot
(I've had them from cooking) take a long time to heal. 
15 Nov
15 Nov
10:06 a.m.
At 06:17 PM 11/14/05 +0000, Jules wrote:
My only caution would be that gold/ceramic ICs tend to have markings
printed on with an ink that detergent will remove quite nicely (made
that mistake once when cleaning a PCB, won't be doing it again :) Other
components seem to survive such cleanings quite happily though.
Speaking of gold/white ceramic ICs. I found a stash of NOS RCA 1801 CPUs
last week. Some of them were stored in that nasty black antistatic foam
that disintegrates with age and the ICs are now fused with the foam. I've
tried to pull a couple of them out and some of the legs broke off of them.
Does anyone know a way to dissolve the foam or anothe rway to get the ICs
out without damaging them? Luckily many of the CPUs are still in their
original RCA packages so they're PRISTINE!
Joe
3:30 p.m.
>>>> "Joe" == Joe R <rigdonj
at cfl.rr.com> writes:
Joe> At 06:17 PM 11/14/05 +0000, Jules wrote:
> My only caution would be that gold/ceramic ICs
tend to have
> markings printed on with an ink that detergent will remove quite
> nicely (made that mistake once when cleaning a PCB, won't be doing
> it again :) Other components seem to survive such cleanings quite
> happily though.
Joe> Speaking of gold/white ceramic ICs. I found a stash of NOS RCA
Joe> 1801 CPUs last week. Some of them were stored in that nasty
Joe> black antistatic foam that disintegrates with age and the ICs
Joe> are now fused with the foam. I've tried to pull a couple of them
Joe> out and some of the legs broke off of them. Does anyone know a
Joe> way to dissolve the foam ...
Don't know if it will help here, but I keep a bottle of lacquer
thinner around the garage. It dissolves lots of stuff -- it's the
best thing I have found for removing adhesive labels of all kinds
(other than benzene which is hard to get these days). It also attacks
most types of plastic, so it isn't suitable for cleaning them. But it
might be good for dissolving one.
If that doesn't work, try acetone. Usually, if a plastic is soluble
at all, it will be soluble in one of those two. (Hm, not always --
vinyl requires something special. Look at the ingredients list on a
waterbed patch kit. Hexane? Something like that.)
paul
3:53 p.m.
On 11/15/2005 at 10:06 AM Joe R. wrote:
Speaking of gold/white ceramic ICs. I found a stash
of NOS RCA 1801
CPUs
last week. Some of them were stored in that nasty black
antistatic foam
that disintegrates with age and the ICs are now fused with the foam. I've
tried to pull a couple of them out and some of the legs broke off of them.
Does anyone know a way to dissolve the foam or anothe rway to get the ICs
out without damaging them? Luckily many of the CPUs are still in their
original RCA packages so they're PRISTINE!
I'd first try soaking the mess in acetone (available at any hardware
store); if that didn't work, try some methylene chloride, which will
dissolve most anything that's dissolvable. You can get it (or at least
liquid paint strippers that contain it) at most good paint stores.
Follow precautions printed on the container. Fumes from either of these
are nasty. Methylene chloride is murder on your skin and eyes and is a
class 3 carcinogen.
Cheers,
Chuck
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cclist＠sydex.com -
dwight.elvey＠amd.com -
julesrichardsonuk＠yahoo.co.uk -
pkoning＠equallogic.com -
rigdonj＠cfl.rr.com