8 Jun
2012
8 Jun
'12
3:30 a.m.
I have two Mac logic boards (an LC and a Quadra 700) which came
to me after the PRAM batteries had exploded, leaving a pretty
awful mess. The good news is that there doesn't seem to be any
permanent trace damage, and none of the surrounding parts were
blown away except for a cheap, easily-replaced SMT diode.
However, the last bits of the terminals for the battery holders
are still in the holes. With careful application of abrasives
and solvent, I managed to clean them to shiny metal, but they're
resisting desoldering pretty well (they seem to be mostly rust
or similar corroded detritus at this point).
Anyone have tips on removing corroded battery terminals from a
PCB?
- Dave
8:40 a.m.
On Jun 8, 2012, at 11:32 AM, Chuck Guzis wrote:
On 8 Jun 2012 at 6:30, David Riley wrote:
The big problem is that the ground terminal connects to an
internal plane, not a surface trace. I'd be worried about
removing the hole plating with the drill. I suppose, since
it's going to ground, it would be easy enough to white-wire
to another known ground point, but I'd like to avoid that
approach if possible.
Still, it should work if all else fails.
- Dave
Anyone have tips on removing corroded battery
terminals from a
PCB?
Given that it's a battery, why not just drill them out? 
9:28 a.m.
On 8 Jun 2012 at 11:40, David Riley wrote:
The big problem is that the ground terminal connects
to an
internal plane, not a surface trace. I'd be worried about
removing the hole plating with the drill. I suppose, since
it's going to ground, it would be easy enough to white-wire
to another known ground point, but I'd like to avoid that
approach if possible.
Use enough heat--those inner ground-plane connections will suck the
soul out of a standard 40W TC iron. As others have mentioned, add
solder to it while you work.
--Chuck
9 Jun
9 Jun
9:08 a.m.
On Jun 8, 2012, at 12:28 PM, Chuck Guzis wrote:
On 8 Jun 2012 at 11:40, David Riley wrote:
Right - I have enough desoldering experience to know to keep
it wet (it's more intuitive than you might think, as molten
lead is a much better heat carrier than a point contact). I
guess it's getting about time for me to upgrade from the 30W
Weller fire-starter I've been using for years, though.
I guess most of my question boils down to the fact that the
pins seem to have corroded all the way through, so I didn't
think they'd be particularly amenable to conventional
extraction. CAIG Flux-Off seems to do fairly well for
removing the worst of the corrosion once sufficiently abraded,
but I suppose DeOx-It would be a better candidate if I had any.
- Dave
The big problem is that the ground terminal
connects to an
internal plane, not a surface trace. I'd be worried about
removing the hole plating with the drill. I suppose, since
it's going to ground, it would be easy enough to white-wire
to another known ground point, but I'd like to avoid that
approach if possible.
Use enough heat--those inner ground-plane connections will suck the
soul out of a standard 40W TC iron. As others have mentioned, add
solder to it while you work. 
6:45 a.m.
Right - I have enough desoldering experience to know
to keep
it wet (it's more intuitive than you might think, as molten
lead is a much better heat carrier than a point contact). I
guess it's getting about time for me to upgrade from the 30W
Weller fire-starter I've been using for years, though.
I guess most of my question boils down to the fact that the
pins seem to have corroded all the way through, so I didn't
think they'd be particularly amenable to conventional
extraction. CAIG Flux-Off seems to do fairly well for
removing the worst of the corrosion once sufficiently abraded,
but I suppose DeOx-It would be a better candidate if I had any.
Dave, I'd recommend the Hakko FX-888. It's a very nice iron and can be
had for around $80.
g.
--
Proud owner of F-15C 80-0007
http://www.f15sim.com - The only one of its kind.
http://www.diy-cockpits.org/coll - Go Collimated or Go Home.
Some people collect things for a hobby. Geeks collect hobbies.
ScarletDME - The red hot Data Management Environment
A Multi-Value database for the masses, not the classes.
http://www.scarletdme.org - Get it _today_!
Buying desktop hardware and installing a server OS doesn't make a
server-class system any more than sitting in a puddle makes you a duck.
[Cipher in a.s.r]
8 Jun
8 Jun
12:41 p.m.
On 8 Jun 2012 at 6:30, David Riley wrote:
Do you _know_ that there are no connections to internal layers of the
board? Drilling out the solder will most likely damage the throuhg-hole
plating.
-tony
Anyone have tips on removing corroded battery
terminals from a
PCB?
Given that it's a battery, why not just drill them out?
1:26 p.m.
On 8 Jun 2012 at 20:41, Tony Duell wrote:
Do you _know_ that there are no connections to
internal layers of the
board? Drilling out the solder will most likely damage the
throuhg-hole plating.
As David noted, if the connection is to the buried ground plane,
alternate connections are available, should you slip with your #70
bit.
--Chuck
12:37 p.m.
However, the last bits of the terminals for the
battery holders
are still in the holes. With careful application of abrasives
and solvent, I managed to clean them to shiny metal, but they're
Have you tried a weak acid, like citric acid? I've found thst helps a lot.
resisting desoldering pretty well (they seem to be
mostly rust
or similar corroded detritus at this point).
Anyone have tips on removing corroded battery terminals from a
PCB?
The other thing that often helps is to melt some new sodler onto the
connections.
-tony
4896
days inactive
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days old
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