Soldering iron problems

[Antony Gelberg]

Hi,

I know this should be simple but isn't. I need to resolder a DC power
connector on a laptop, due to dry joints.

I can't find my old, rarely used soldering iron, so I went to Maplin and
bought their cheapo 30W soldering iron.
http://www.maplin.co.uk/module.aspx?ModuleNo=32909&doy=13m6

I would have thought that is good enough for PCB soldering, but I can barely
get the old solder on the board to melt, let alone re-solder the joint. I
can't work like this, I'm going to arse about for hours and still not get it
done properly. Is the problem likely to be the fine point nib that it came
with? I have always used flat-tip bits in the past. Or is the Maplin iron
crap, and should I have bought the Antek 30W instead -
http://www.maplin.co.uk/Module.aspx?ModuleNo=45545&&source=14&doy=13m6 ?

All advice appreciated.

I should mention that I also tried my 100W soldering gun, like this one:
http://tinyurl.com/2z8ehn .

No luck here, but then I have always hated this tool and never been able to
use it effectively. It's rated for 12 seconds use in a minute (don't know
what happens if you go above that), but takes about 9 seconds to even get hot
enough to melt solder. Are these crap, or am I not using the thing properly?

Antony

 

[Antony Gelberg]

Make sure the tip is tight.
Yep.

Make sure you're using the correct solder?, 60 tin and 40 lead for
repair work.
Use some extra solder paste to clean the area..
It's possible you have Lead Free Solder, that's hard to work with..

It is lead free, but that doesn't matter when I'm trying to desolder the OEM
joint. I think it's just not hot enough but I'm surprised - I thought 30W
would be plenty.

 

[mc]

Do some practicing with other things first. A few things:

- As someone pointed out, you may have lead-free solder, which has a higher
melting point. But you should use it for the repair, since the connector
probably has the same stuff already on it.

- There may be an invisible coating on the soldering iron tip, or it may not
be properly tinned. The last couple of mm of the tip should have a coating
of melted solder, applied by you.

- Some coaxial connectors have a nickel (?) coating that is hard to solder.
Using fine sandpaper on them really helps, as does a rotary wire brush.

Your soldering iron looks fine (low-end, of course). Is the tip tightly
attached? Try loosening and retightening the screw while it is hot (use
care).

 

[Jamie]

Hi,

I know this should be simple but isn't. I need to resolder a DC power
connector on a laptop, due to dry joints.

I can't find my old, rarely used soldering iron, so I went to Maplin and
bought their cheapo 30W soldering iron.
http://www.maplin.co.uk/module.aspx?ModuleNo=32909&doy=13m6

I would have thought that is good enough for PCB soldering, but I can barely
get the old solder on the board to melt, let alone re-solder the joint. I
can't work like this, I'm going to arse about for hours and still not get it
done properly. Is the problem likely to be the fine point nib that it came
with? I have always used flat-tip bits in the past. Or is the Maplin iron
crap, and should I have bought the Antek 30W instead -
http://www.maplin.co.uk/Module.aspx?ModuleNo=45545&&source=14&doy=13m6 ?

All advice appreciated.

I should mention that I also tried my 100W soldering gun, like this one:
http://tinyurl.com/2z8ehn .

No luck here, but then I have always hated this tool and never been able to
use it effectively. It's rated for 12 seconds use in a minute (don't know
what happens if you go above that), but takes about 9 seconds to even get hot
enough to melt solder. Are these crap, or am I not using the thing properly?

Antony

Make sure the tip is tight.
Make sure you're using the correct solder?, 60 tin and 40 lead for
repair work.
Use some extra solder paste to clean the area..
It's possible you have Lead Free Solder, that's hard to work with..

 

[Antony Gelberg]

Do some practicing with other things first. A few things:

- As someone pointed out, you may have lead-free solder, which has a higher
melting point. But you should use it for the repair, since the connector
probably has the same stuff already on it.

I'm just trying to desolder the existing joints at the moment.

- There may be an invisible coating on the soldering iron tip, or it may not
be properly tinned. The last couple of mm of the tip should have a coating
of melted solder, applied by you.

It does.

- Some coaxial connectors have a nickel (?) coating that is hard to solder.
Using fine sandpaper on them really helps, as does a rotary wire brush.

But would this stop me desoldering existing joints?

Your soldering iron looks fine (low-end, of course). Is the tip tightly
attached? Try loosening and retightening the screw while it is hot (use
care).

It's back in the packaging. Don't think swapping it for a 50W iron is a
better idea? How about a flat tip instead of fine point?

 

[BH]

Do some practicing with other things first. A few things:

- As someone pointed out, you may have lead-free solder, which has a higher
melting point. But you should use it for the repair, since the connector
probably has the same stuff already on it.

- There may be an invisible coating on the soldering iron tip, or it may not
be properly tinned. The last couple of mm of the tip should have a coating
of melted solder, applied by you.

- Some coaxial connectors have a nickel (?) coating that is hard to solder.
Using fine sandpaper on them really helps, as does a rotary wire brush.

Your soldering iron looks fine (low-end, of course). Is the tip tightly
attached? Try loosening and retightening the screw while it is hot (use
care).

Mass is more important that wattage.

BH

 

[Arfa Daily]

Hi,

I know this should be simple but isn't. I need to resolder a DC power
connector on a laptop, due to dry joints.

I can't find my old, rarely used soldering iron, so I went to Maplin and
bought their cheapo 30W soldering iron.
http://www.maplin.co.uk/module.aspx?ModuleNo=32909&doy=13m6

I would have thought that is good enough for PCB soldering, but I can
barely
get the old solder on the board to melt, let alone re-solder the joint. I
can't work like this, I'm going to arse about for hours and still not get
it
done properly. Is the problem likely to be the fine point nib that it
came
with? I have always used flat-tip bits in the past. Or is the Maplin
iron
crap, and should I have bought the Antek 30W instead -
http://www.maplin.co.uk/Module.aspx?ModuleNo=45545&&source=14&doy=13m6 ?

All advice appreciated.

I should mention that I also tried my 100W soldering gun, like this one:
http://tinyurl.com/2z8ehn .

No luck here, but then I have always hated this tool and never been able
to
use it effectively. It's rated for 12 seconds use in a minute (don't know
what happens if you go above that), but takes about 9 seconds to even get
hot
enough to melt solder. Are these crap, or am I not using the thing
properly?

Antony

If the laptop was manufactured fairly recently, it will have been
constructed with lead-free solder - dull grey looking joints, and the board
may have "Pb Free" or "PbF" either etched or silk screened on it. If it is
lead-free, then there is your first problem, as the melting point is higher
than solder that you are used to. The second problem is that you are
attempting to solder a fairly large component, that will leech heat out of
an iron very quickly, which brings us to the next point that the iron used
must have good thermal inertia to overcome this effect, and a pointy tip is
far from ideal to achieve this. Also, 30 watts may be a bit on the low side,
particularly if it is lead-free solder. On the other hand, I would have said
that the job *could* be done with that iron, by a person used to soldering
daily. Remember for a start that old solder - even leaded - is much more
difficult to melt than new, and it is usual to feed some new solder into an
old joint, before sucking or wicking the joint clean.

As far as your Weller gun goes, this should easily be able to cope. I still
have my original one of these with a black bakelite casing, from when they
first came out over 40 years ago, and it still works as good as new. Yours
should certainly not take 9 seconds to get hot. 3 seconds tops. The problem
is that you are not slackening and re-tightning the bit-wire retainer nuts.
These irons work by the bit being a short circuit across a single turn
transformer secondary, the primary being a coil connected directly across
the mains. The single turn produces a low voltage, but with huge amounts of
amps flowing round it, via the copper bit-wire, which then gets very hot as
a result. However, the surface of this (soft) copper wire oxidises from the
heat, and the resistance of the contact points, under the retainer nuts,
goes up. It only needs to go up by a few tens of milliohms, to significantly
reduce the current flowing round the shorted turn, and hence the amount of
heat being generated in the bit.

Click the iron's trigger on, and whilst holding it on, take your bit
retainer nut spanner, and back each nut off a half turn, and re-tighten, one
at a time. That should then give you virtually 'instant' heat each time you
trigger it on, for the rest of the soldering session. You should repeat this
procedure whenever you get the iron out to use. As far as exceeding the duty
cycle of the gun, I have done this many many times. The effect is that the
case becomes uncomfortably hot to hold, as a result of the transformer
primary winding overheating. I suppose that if you managed to hold onto it
for long enough, the insulation on the wire making the winding would fail,
but I think that you would be seriously burning your hand by the time this
happened, and already, your nose would be telling you to stop ...

Arfa

 

[Jamie]

It is lead free, but that doesn't matter when I'm trying to desolder the OEM
joint. I think it's just not hot enough but I'm surprised - I thought 30W
would be plenty.

My desoldering tool can do up to 60 watts/. I would get something in
the line of 45 watts or so for desoldering Lead Free or, mix in some
Leaded solder to soften it.

 

[Antony Gelberg]

Mass is more important that wattage.

Mass of the tip, correct?

 

[W Gray]

Greetings.

I hope this message finds you well.

This may sound like a dumb question, but have you tinned the tip of your
soldering iron?

-W Gray

 

[Steve Sousa]

Hi,

I know this should be simple but isn't. I need to resolder a DC power
connector on a laptop, due to dry joints.

I can't find my old, rarely used soldering iron, so I went to Maplin
and
bought their cheapo 30W soldering iron.
http://www.maplin.co.uk/module.aspx?ModuleNo=32909&doy=13m6

I would have thought that is good enough for PCB soldering, but I can
barely
get the old solder on the board to melt, let alone re-solder the
joint. I

Hello:

The why's of your problem have been explained by other posters.
You can solder your dc jack with your 30 watt or the pistol, better yet,
get a friend and use both, however, there is a trick to it: you have to
preheat the pcb.

To do so, get a hair drier, set it on max and slowly start heating a
large area of the board from a distance of 20cms (8inch), then start
aproaching and concentrating on the jack, it takes about 5 minutes to do
it properly, your board will be very warm overall, then heat the board
directly above and bellow the jack with the hairdrier nearly touching
them, do this for about 3 seconds each side, repeat about 4 or 5 times,
then and only then use the solder iron to remove the jack, if you have a
friend you can use both irons, the pistol on the ground connection the
other on the other pins. the jack should fall off. be very gentle with
the pistol if you use it, because the board is allready hot, such beast
will easily damage it if you aproach it like you did when it was cold.

P.S: to use the pistol *first* heat it enough to melt solder *then*
touch the parts then turn on-off-on-off at about 1Hz.

Best regards

Steve Sousa

 

[Jerry G.]

The soldering iron has to have the right temperature, and have enough
BTU's to heat the connection. Make sure you are using 60-40 type
solder.

A proper soldering station is what is normaly used. This will allow
for proper temperature control, and can put out enough BTU's of heat.

If you do not have a lot of experience at soldering on to circuit
boards, it is very easy to damage the solder pads and traces on the
board. This is especialy true with multi-layer boards. This type of
damage takes a lot of experience to fix, it is not easily repairable.
Not having the proper tools and experience can usually lead to
damaging the circuit board, and sometimes the components that are
being heated.


Jerry G.
======

 

[Smitty Two]

It is lead free, but that doesn't matter when I'm trying to desolder the OEM
joint. I think it's just not hot enough but I'm surprised - I thought 30W
would be plenty.

You need flux. I'm surprised my friend Arfa didn't mention that in his
otherwise thorough treatise.

 

[mc]

I'm just trying to desolder the existing joints at the moment.

Ah. They may have a clear plastic coating.

It's back in the packaging. Don't think swapping it for a 50W iron is
a
better idea? How about a flat tip instead of fine point?

30W is plenty for electronics; 15W would do.

 

[Arfa Daily]

You need flux. I'm surprised my friend Arfa didn't mention that in his
otherwise thorough treatise.

Hi Smitty

I was taking that as a 'given' by assuming that the OP was using
conventional flux-cored solder for his attempts, so flux would be
automatically put into the equation when new solder was added to the old to
help the melting process. However, if he's not, you're dead right, and I
should probably have made that clearer as being part of the reason for
adding new solder to the old joint ;-)

Arfa

 

[Morse]

Hi,

I know this should be simple but isn't. I need to resolder a DC power
connector on a laptop, due to dry joints.

I can't find my old, rarely used soldering iron, so I went to Maplin and
bought their cheapo 30W soldering iron.
http://www.maplin.co.uk/module.aspx?ModuleNo=32909&doy=13m6

I would have thought that is good enough for PCB soldering, but I can
barely
get the old solder on the board to melt, let alone re-solder the joint. I
can't work like this, I'm going to arse about for hours and still not get
it
done properly. Is the problem likely to be the fine point nib that it
came
with? I have always used flat-tip bits in the past. Or is the Maplin
iron crap, and should I have bought the Antek 30W instead -
http://www.maplin.co.uk/Module.aspx?ModuleNo=45545&&source=14&doy=13m6 ?

All advice appreciated.

Antony,

If you can borrow a temperature controlled iron, preferably one in the
45-50watt region, with a fairly broad tip, you should be able to do the job
fairly easily.

What is happening is the large area of the multilayer PCB, combined with the
rather large track area, is siphoning away the heat from the tip and
chilling it. The iron is not temperature controlled so cannot compensate,
so its temperature drops below the required heat to melt solder.

If you keep trying with your iron, you will soon destroy the socket, board
and PCB pads- the job must be done quickly with a hot iron. I have replaced
several laptop power connectors and feel that a cheap hobbyist's iron in
the majority of cases would be quite inadequate.


Try eBay- I've seen old Weller magnastat soldering stations for about 15
UKP. Usually tatty to look at but they do a great job. I still use one
myself! The temperature is set by tip selection, and there's not much they
can't do with a hot tip fitted. Alternatively there's occasionally Antex
stations with user-variable temperature dials which go for a reasonable
amount. If you intend on servicing your own stuff you really need a
temperature controlled iron.

I should mention that I also tried my 100W soldering gun, like this one:
http://tinyurl.com/2z8ehn .

No luck here, but then I have always hated this tool and never been able
to
use it effectively. It's rated for 12 seconds use in a minute (don't know
what happens if you go above that), but takes about 9 seconds to even get
hot
enough to melt solder. Are these crap, or am I not using the thing
properly?

Soldering guns are OK for the appropriate job but not really for PCB use
because they can only administer very high heat for short bursts and need
cooling off time before they can be operated again.

To answer your question- exceeding the time will burn out the transformer
inside! The one I once used went off with quite a loud pop!

Morse

 

[mc]

If you can borrow a temperature controlled iron, preferably one in the

45-50watt region, with a fairly broad tip, you should be able to do the
job
fairly easily.

What is happening is the large area of the multilayer PCB, combined with
the
rather large track area, is siphoning away the heat from the tip and
chilling it. The iron is not temperature controlled so cannot compensate,
so its temperature drops below the required heat to melt solder.

If you keep trying with your iron, you will soon destroy the socket, board
and PCB pads- the job must be done quickly with a hot iron. I have
replaced
several laptop power connectors and feel that a cheap hobbyist's iron in
the majority of cases would be quite inadequate.

I agree. When I said earlier that 30 watts is plenty, I hadn't quite
realized he was wanting to remove something with a substantial amount of
metal that needs heating up.

 

[Michael Kennedy]

I agree. When I said earlier that 30 watts is plenty, I hadn't quite
realized he was wanting to remove something with a substantial amount of
metal that needs heating up.

I've had success doing what you want to by using the largest iorn I can find
and working really fast so that you don't destroy the board. I'd immagine a
45 - 50 Watt iorn would work well. Just don't leave the iorn on the board
more than a few seconds, just long enough to liquify the solder and add some
more. You will cook those solder pads if you use too small of an iorn or
take too long with a big one!

Mike

 

[Smitty Two]

If you can borrow a temperature controlled iron, preferably one in the
45-50watt region, with a fairly broad tip, you should be able to do the
job
fairly easily.

What is happening is the large area of the multilayer PCB, combined with
the
rather large track area, is siphoning away the heat from the tip and
chilling it. The iron is not temperature controlled so cannot compensate,
so its temperature drops below the required heat to melt solder.

If you keep trying with your iron, you will soon destroy the socket, board
and PCB pads- the job must be done quickly with a hot iron. I have
replaced
several laptop power connectors and feel that a cheap hobbyist's iron in
the majority of cases would be quite inadequate.

I agree. When I said earlier that 30 watts is plenty, I hadn't quite
realized he was wanting to remove something with a substantial amount of
metal that needs heating up.[/QUOTE]

OP: Again - Before you invest $100 or more in a quality iron - which I
highly recommend - beg, borrow, buy or steal a couple of ounces of
liquid flux. A drop or two will make a world of difference in your
ability to reflow the old solder. Trust me on this one. You might just
be able to get by with the light duty iron if you use flux, and you'll
need it anyway even if you buy the better iron. And don't use the point
of the tip. Choke up on it a bit, where there's more thermal mass.

 

[GregS]

I've had success doing what you want to by using the largest iorn I can find
and working really fast so that you don't destroy the board. I'd immagine a
45 - 50 Watt iorn would work well. Just don't leave the iorn on the board
more than a few seconds, just long enough to liquify the solder and add some
more. You will cook those solder pads if you use too small of an iorn or
take too long with a big one!

After working with the Weller rework station, all the other irons seem
way to large for the hand. The Weller being smaller in size is not small
on watts. 80 watts. Pleasure to work with.When I need big watts, i get
out the 250 watt Radio Shack gun.


greg