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From: Jon Danniken on 16 Mar 2010 09:37
123Jim wrote:
> Another suggestion I read somewhere
> was to use a wick. Copper I think. The idea I think is to heat the
> solder, apply some copper wire to it, and it might be attracted to
> the copper and remove it's molten self from the joint. but I never
> reached the point where solder of any quantity in my Dell jack made
> it to the liquid state. I began to think it was no ordinary solder
> but solder that would only be liquid above any heat I could apply.

Solder wick is used between the iron and the solder. You heat up the braid
(like you would a wire you are soldering), and the hot braid melts the
solder into it.

Not sure why you aren't able to melt the solder, though, although the new
silver solders can be a bear to work with.

Jon


From: larry moe 'n curly on 16 Mar 2010 10:08


123Jim wrote:
>
> I was trying to replace a power jack on an inspiron 1501 laptop. An
> operation I have avoided for some time due to the possible outcome being the
> catastrophic destruction of the motherboard or components thereof.
>
> I removed the motherboard , but could not melt the solder sufficiently to
> release the power jack. I used two different 30 watt soldering irons with
> sharp and not so sharp iron points and one 100 watt soldering gun.
>
> My technique leaves a lot to be desired: place motherboard on newspaper,
> place finger under motherboard next to jack, apply iron to one joint at a
> time so that it melts the solder and pushes through. unfortunately there
> being 8 joints and stubborn solder made it impossible to move. The best way
> would be to heat all eight joints simultaneously, but I have no idea how to
> achieve that.

BadCaps.net has a guide for unsoldering capacitors, and there are
probably some YouTube videos about soldering and desoldering. 30W
isn't enough power for multilayer boards, especially for components
that go through holes (as opposed to surface mount components),
especially if they go into the ground or power planes, as power
connectors do. OTOH 100W is way too much power, and soldering guns
don't work very well on circuit boards. I'd use a 50W iron with a
very clean, well-tinned tip, preferably a chisel tip. A clean tip
conducts heat a LOT better than a dirty one does, so frequently wipe
off the tip with a damp cloth or paper towel or copper or brass curly
hair (stocked next to the Brillo pads), not with a sponge (leaves a
coating on the tip). Apply regular 60-63% tin, 37-40% lead solder to
the joints because the solder used by the factory has a higher melting
point, even if it's not lead-free. Try to suck it up with copper
desoldering braid (Radio Shack, electronic parts supplies, about
0.080" wide is a good size). Cut off the used braid immediately after
it absorbs solder because dangling used braid will divert heat away
from the soldering joint. When the hole is clear of solder, wiggle
the lead sideways to make sure it's broken free from the solder, and
do NOT pull out the lead or the copper traces will pull out. If more
than a very thin layer of solder remains and you can't get rid of it,
start all over by applying fresh solder.

Some people use solder suckers instead of braid, and the best ones
have a spring-loaded plunger instead of a turkey baster rubber bulb.
But one problem with them is that they jerk and bump the circuit board
when the spring is released, and that may cause damage. Some people
fix that by attaching a very short length of rubber tubing to the tip
to absorb the shocks, but don't use vinyl because it will melt.
Silicone rubber is best (hobby shops, medical supplies -- non-sterile
can be a lot cheaper than sterile).

The safest way to remove solder, without using an electrically
operated vacuum pump, is with a special low temperature solder called
Chip Quik. It's not cheap, about $1 an inch, but is still a lot less
than a new motherboard. There's a YouTube video showing its use.

You should first practice on some junked circuit boards that have at
least 4 layers of copper.
From: 123Jim on 16 Mar 2010 10:35

"larry moe 'n curly" <larrymoencurly(a)my-deja.com> wrote in message
news:afd15ec9-9d99-4b98-b345-7bb751b39202(a)z1g2000prc.googlegroups.com...
>
>
> 123Jim wrote:
>>
>> I was trying to replace a power jack on an inspiron 1501 laptop. An
>> operation I have avoided for some time due to the possible outcome being
>> the
>> catastrophic destruction of the motherboard or components thereof.
>>
>> I removed the motherboard , but could not melt the solder sufficiently
>> to
>> release the power jack. I used two different 30 watt soldering irons with
>> sharp and not so sharp iron points and one 100 watt soldering gun.
>>
>> My technique leaves a lot to be desired: place motherboard on newspaper,
>> place finger under motherboard next to jack, apply iron to one joint at a
>> time so that it melts the solder and pushes through. unfortunately there
>> being 8 joints and stubborn solder made it impossible to move. The best
>> way
>> would be to heat all eight joints simultaneously, but I have no idea how
>> to
>> achieve that.
>
> BadCaps.net has a guide for unsoldering capacitors, and there are
> probably some YouTube videos about soldering and desoldering. 30W
> isn't enough power for multilayer boards, especially for components
> that go through holes (as opposed to surface mount components),
> especially if they go into the ground or power planes, as power
> connectors do. OTOH 100W is way too much power, and soldering guns
> don't work very well on circuit boards. I'd use a 50W iron with a
> very clean, well-tinned tip, preferably a chisel tip. A clean tip
> conducts heat a LOT better than a dirty one does, so frequently wipe
> off the tip with a damp cloth or paper towel or copper or brass curly
> hair (stocked next to the Brillo pads), not with a sponge (leaves a
> coating on the tip). Apply regular 60-63% tin, 37-40% lead solder to
> the joints because the solder used by the factory has a higher melting
> point, even if it's not lead-free. Try to suck it up with copper
> desoldering braid (Radio Shack, electronic parts supplies, about
> 0.080" wide is a good size). Cut off the used braid immediately after
> it absorbs solder because dangling used braid will divert heat away
> from the soldering joint. When the hole is clear of solder, wiggle
> the lead sideways to make sure it's broken free from the solder, and
> do NOT pull out the lead or the copper traces will pull out. If more
> than a very thin layer of solder remains and you can't get rid of it,
> start all over by applying fresh solder.
>
> Some people use solder suckers instead of braid, and the best ones
> have a spring-loaded plunger instead of a turkey baster rubber bulb.
> But one problem with them is that they jerk and bump the circuit board
> when the spring is released, and that may cause damage. Some people
> fix that by attaching a very short length of rubber tubing to the tip
> to absorb the shocks, but don't use vinyl because it will melt.
> Silicone rubber is best (hobby shops, medical supplies -- non-sterile
> can be a lot cheaper than sterile).
>
> The safest way to remove solder, without using an electrically
> operated vacuum pump, is with a special low temperature solder called
> Chip Quik. It's not cheap, about $1 an inch, but is still a lot less
> than a new motherboard. There's a YouTube video showing its use.
>
> You should first practice on some junked circuit boards that have at
> least 4 layers of copper.


Thanks, good stuff.


From: 123Jim on 16 Mar 2010 10:35

"123Jim" <jnkjnjnini(a)uhnuhnunuhnuy.invalid> wrote in message
news:hnnht7$f95$1(a)news.eternal-september.org...
> Hi all,
> I was trying to replace a power jack on an inspiron 1501 laptop. An
> operation I have avoided for some time due to the possible outcome being
> the catastrophic destruction of the motherboard or components thereof.
>
> I removed the motherboard , but could not melt the solder sufficiently to
> release the power jack. I used two different 30 watt soldering irons with
> sharp and not so sharp iron points and one 100 watt soldering gun.
>
> My technique leaves a lot to be desired: place motherboard on newspaper,
> place finger under motherboard next to jack, apply iron to one joint at a
> time so that it melts the solder and pushes through. unfortunately there
> being 8 joints and stubborn solder made it impossible to move. The best
> way would be to heat all eight joints simultaneously, but I have no idea
> how to achieve that.
>
> what I need is a nice soldering guide, specifically for computer parts.
>
> any ideas?
> cheers

Thanks to all those who have replied.
I learned a lot!


From: Paul on 16 Mar 2010 10:56
123Jim wrote:

> Great stuff...
>
> I also found this;
> http://www.aaroncake.net/electronics/desolder.htm
>
> I should have used a solder pump or a wick on the miniscule amount of solder
> I managed to melt .. at least I think I did..
>
> If I had added ordinary solder to the joints I was heating .. would that
> have allowed the heat to melt the target joint? .. I tried that briefly, but
> the solder just bounced past the target joint . and threatened to make a
> mess .. so I only tried it once and gave up.
>
> The laugh is I have some things I would like to try again .. but I won't be
> disassembling this laptop again until it is officially dead for a second
> time. :)
>
>

One reason the solder won't melt, is when there is a solid copper plane
connected to the plated component hole. The solid copper acts as
a heat sink, and drains heat from the soldering iron tip. There
are PCB design techniques to improve the situation, but modern
board designs don't seem to be too interested in that. And the reason
for that, is the factory soldering equipment, like IR reflow, just
heats up everything during the soldering process, and it doesn't
matter that hand soldering would be made tougher by the way the PCB
is designed.

You can tin the tip of the iron, to put a "fresh coat" on it and improve
thermal conductivity. But the practice of doing that, can dissolve the
metal of the tip of the iron. So it could result in you needing to purchase
a new tip sooner. But my experience is, it is better to tin the tip of
the iron occasionally, then just "burn it brown" and make it totally
non-conductive. I've worked with plenty of people who just ruin the
tips on the irons they use. I tend to shut off my iron when not using
it, and tin and clean the tip when I'm done.

You can also melt a little solder, in an effort to get heat to
flow into the hole. But if the PCB is sinking all the heat, you
can end up with a blobby mess, and the need to say more curse words.

The largest iron I've seen personally, is the one in metal shop in
school. We used to make tin plate boxes with those irons, and they
run somewhere around 200-250W. But the tip on those irons is so big,
you'd never get it near electronics.

At one time, I used to do soldering with the gun style device.
Until I burned it out, by exceeding the duty cycle. I would
never recommend buying one of those to someone now, as it
is easy to get carried away and overheat it. The pencil style
irons can have grounded tips, or better provision for electrostatic
discharge, than the gun style solution. If the pencil iron has
a three pronged plug, then chances are the tip is grounded. And that
may allow your antistatic bench setup, to better protect the project
you're working on. (All devices, including soldering iron tip, are
at the same electrostatic potential.) That avoids tiny "arcs and
sparks" that might damage sensitive components.

http://upload.wikimedia.org/wikipedia/commons/thumb/d/d7/SolderGun.jpg/800px-SolderGun.jpg

Paul
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