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Author Topic: Soldering - what am I doing wrong?  (Read 3887 times)

RipSlider

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Soldering - what am I doing wrong?
« on: October 18, 2007, 02:17:42 PM »

Hello all.

This is a slightly embarrassing question, but I am, honestly, struggling to make simple solder joints in wires at the moment.

The issue is that the joints either seem very dull and rough, which is a poor joint, or dirty, with black streaks in a shiny soldered joint.

This is my process, I will give an example from last night of soldering up a wiring harness for my boat:

1) dip wire A in flux briefly
2) Twist wire
3) Dip soldering iron into flux
4) wipe rapidly in a clean damp rag
5) Tin the wire ( Use iron to get wire hot, and then run in solder and let it wick )
6) Push wire through motors connection terminal and twist
7) Re-heat with iron
8) run solder into now hot joint


Of note is that the iron's tip is constantly discoloured aqnd I haven' found any way top get it to a "clean" colour, and that the solder seems to be very low in lead content, as when I've tinned a wire it will hardly bend at all it's that stiff.

So, is it my technique, an issue with the iron or an issue with the solder?

Any thoughts at all greatly appreciated.

Steve
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HS93 (RIP)

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Re: Soldering - what am I doing wrong?
« Reply #1 on: October 18, 2007, 02:28:58 PM »

Do you tin the Iron before you re heat if not it will not transfer the heat, I have found if you don't tin the iron after cleaning you will take to long to transfer heat .

Peter
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Peterm

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Re: Soldering - what am I doing wrong?
« Reply #2 on: October 18, 2007, 03:33:16 PM »

I just use flux-cored solder.   Make sure the bits to be joined are clean, apply solder and iron to each end in turn, hold the ends together and apply iron.   Works for me, (and has done for the last 45 years.)   Pete M
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malcolmfrary

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Re: Soldering - what am I doing wrong?
« Reply #3 on: October 18, 2007, 03:37:32 PM »

For 'lectric soldering, I rely on flux cored solder.  Olde worlde irons used to need tinning, which involved much attacking with a file, then getting it hot and dabbing with cored solder in the active area, then a quick wipe to reveal a silvery area.  Modern irons usually have iron coated tips and must never be filed for tinning, as this effectively destroys them.   Get hot, dab of cored solder and wipe to leave a surface of liquid solder on the tip which ensures maximum heat transfer.
If the wire is heavy and untinned, the flux and solder treatment helps, but if the wire is pre-tinned, all that is needed is a quick dab to ensure that the tinned surface has had any layer of oxide removed.
When the mechanical join is made (posh way of saying the wire is wrapped round the tag/other wire) I dab the end of the tip to ensure liquid solder there, touch the joint and apply solder.  Take the iron away as soon as the solder runs, joints a good 'un.  
The secrets are
1 Clean
2 Speed - the iron needs to be hot enogh and big enough so that it doesn't cool down too quickly when in contact with the workpiece.
3 Clean
4 If possible, avoid separate flux, use cored solder
5 Clean
After making the joint, wipe the tip so that it is Clean for the next one.
Stranded wire can be a problem if it has gained an oxide layer, as cleaning it is almost impossible to do reliably.  An acid flux gives the problem of ensuring removal which is vital as thin wires are very easily eaten away, especially when electricty is involved due to electrolysis.
Have a look for someone selling leaded solder, the new muck seems to be a disaster waiting to happen.
There is a most instuctive thread ekswhere about structural soldering, but circuit soldering is a different world.
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bigford

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Re: Soldering - what am I doing wrong?
« Reply #4 on: November 11, 2007, 07:52:51 AM »

what do you use to clean off the flux after your done ??
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HS93 (RIP)

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Re: Soldering - what am I doing wrong?
« Reply #5 on: November 11, 2007, 08:04:02 AM »

I use Isopropyl alcohol I think they call it Denatured alcohol over there. I get a small Paint brush followed by a small brass brush  or if it can be dipped (without damage to othere parts). some people use  Cellulose Thinners.

Peter
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Colin Bishop

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Re: Soldering - what am I doing wrong?
« Reply #6 on: November 11, 2007, 10:33:54 AM »

Quote
I use Isopropyl alcohol I think they call it Denatured alcohol over there.

Thanks for that tip. I bought 10 litres of it in a French supermarket a year or so ago for use in my 1:1 boat's alcohol stove (it cost about 7) but I'm finding it is coming in useful for all sorts of things - one more for the list.

Don't let it near Tamiya acrylic painted surfaces though, strips off the paint like lightning!
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RipSlider

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Re: Soldering - what am I doing wrong?
« Reply #7 on: November 11, 2007, 12:19:58 PM »

Well gentlemen.

A progress report on the soldering:

I tried again, closely following the instructions provided. And I still ended up with dreadful joints.

So, using my initiative, I swore at it, and then passed it to my friend to solder up. And it's come back wonderfully.

Hurrah for accepting defeat and passing the buck!

Steve
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Re: Soldering - what am I doing wrong?
« Reply #8 on: November 11, 2007, 12:31:43 PM »

Looking at what you are doing I would start by tinning the iron then the wire stop the dipping things in flux , as long as you are using NON fluxed solder for wire what is there is enough, clean the tag on the motor with a bit of wet and dry (dry) then tin it , wipe the iron on a damp sponge to clean  RE TIN  (no extra flux) put the two together and heat.
you need to make shore your iron is a nice and shinny when just tinned , you will not transfer heat with a dry iron.
have a play with some scraps of brass and wire, also make shore your iron tip it tight  as a loose tip will cool very quick and will not get up to temperature.

Peter
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Admhawk

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Re: Soldering - what am I doing wrong?
« Reply #9 on: November 11, 2007, 03:52:23 PM »

A couple of things,

Isopropyl alcohol is fantastic for cleaning a lot of things, flux, paint brushes, resin castings before painting etc.

New solder is going leadless and requires a higher temp tip.

Tips should be cleaned with a damp sponge or rag just prior to use, tinned, used, then tinned again to be left for the next time (never leave a clean tip on a cold solder iron, seal it from the air with a layer of solder to prevent corrosion). You might have an old tip (no clean metal to hold the tinning), it might be too small for the job, tips left clean without plating will corrode and not work well. Never use a file or sandpaper on a modern plated tip, through it out and buy a new one.

Liquid solder works fantastic. Rosin core solder is popular among hobbyists, but rarely used by professionals.

Rough, dull surface means not enough heat transfer. ( a trick would be to pile the solder on a hot tip so that it is just about to drip off, then place on joint and let the heat transfer without moving the tip until it all flows off.)

Black bits mean contamination. (carbon from tip or burnt insulation or flux on wire)

Regards,
Darren

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HS93 (RIP)

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Re: Soldering - what am I doing wrong?
« Reply #10 on: November 11, 2007, 04:02:05 PM »


Rosin core solder is popular among hobbyists, but rarely used by professionals.


What for soldering wires?
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Re: Soldering - what am I doing wrong?
« Reply #11 on: November 11, 2007, 05:57:56 PM »

Well I spend 30 odd years as a "professional" solderer in telephone exchanges and we never used anything but cored solder
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Circlip

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Re: Soldering - what am I doing wrong?
« Reply #12 on: November 11, 2007, 06:29:16 PM »


    Are you still a professional Frankie?  Trouble is with todays ELFIN, we can't be trusted not to poison ourselves
    with Lead and resin (rosin) fumes. Look at Yorkshire fittings,  my tin of FLUXITE, passed down, is superb for
    plumbing jobs, and I managed to 'Acquire' enough reels of ' cored' for any future electronics projects but although
    it hasn't completely dissapeared yet I wonder how long?
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funtimefrankie

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Re: Soldering - what am I doing wrong?
« Reply #13 on: November 11, 2007, 07:02:39 PM »


    Are you still a professional Frankie?  Trouble is with todays ELFIN, we can't be trusted not to poison ourselves
    with Lead and resin (rosin) fumes. Look at Yorkshire fittings,  my tin of FLUXITE, passed down, is superb for
    plumbing jobs, and I managed to 'Acquire' enough reels of ' cored' for any future electronics projects but although
    it hasn't completely dissapeared yet I wonder how long?
No I retired some years ago ;D. I too have a nice big bobbin of cored solder, hopefully enough to see me out.

If anyone wants a couple of yards of real Mans' solder PM me
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wombat

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Re: Soldering - what am I doing wrong?
« Reply #14 on: November 11, 2007, 07:50:36 PM »

Every electronic manufacturing facility I have been in uses rosin cored solder wire for manual assembly of through-hole components where wave soldering is not practical. It is still the method of choice for repairs. Solder paste is great for surface mount components but does not really cut it for through-hole.

I don't see Rosin cored solder wire going away for a long time - it is the best way of controlling the amount of flux used

Riplslider, if you are getting dull joints there are a couple of possibilities....

1/. You are using lead-free solder. Cure - live with it, lead-free joints tend to be dull in colour

2/. You have not got a solid mecanical connection - if the joint moves while it is cooling, the quality of the joint will be poor, especially if there is movment when the solder goes through the "pasty" zone.  Cure - ensure a good mechanical connection either by twisting the wires or by wrapping thin tinned copper wire.

3/. You have tried to cool the joint down too quicky by blowing on it. Cure - don't do it.


Wom
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Circlip

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Re: Soldering - what am I doing wrong?
« Reply #15 on: November 11, 2007, 08:19:14 PM »


  Yes Wombat, our boards were fluxed and waved. My 'Evaluation' TV set used to flare on one colour and could
   cured with a thump on the RHS of the cabinet. This treatment  wouldn't sort it after a couple of years and after
   a strip down and an extensive search the pin on a soldered  in socket was found to have been 'eaten' by the flux.
   We also used to solder in IC sockets but found the flux used to wick up the legs of the sockets, eventually eating
    the IC legs. Yes we solved it.
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barriew

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Re: Soldering - what am I doing wrong?
« Reply #16 on: November 12, 2007, 10:18:57 AM »

I use Isopropyl alcohol I think they call it Denatured alcohol over there. I get a small Paint brush followed by a small brass brush  or if it can be dipped (without damage to othere parts). some people use  Cellulose Thinners.

Peter

Isopropyl alcohol and denatured alcohol are two different things. Denatured is normally ethyl alcohol ( as in booze) with the addition of methyl alcohol - to stop you drinking the good stuff :D

Isopropyl alcohol is used for many cleaning jobs - I first came across it as a young computer operator - we used it to clean the heads on tape drives.

Barrie
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sheerline

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Re: Soldering - what am I doing wrong?
« Reply #17 on: November 12, 2007, 10:51:58 AM »

Just jumping in on this post with my own experience... bin soldering all my life. I noted that you mentioned your tinned and cleaned bit always dried to a dull colour... perhaps your iron is to hot! This may also cause the black streaks on your joints which may be burnt flux. When the flux is burnt off in this manner, the solder will always end up with a dull finish ,look dry and not form around the joint in a nice shiny co-hesive fashion.
Personally, I always use a temperature controlled soldering iron as it can be set to the best operating temperature for the joint. As most solder is now lead free, it is more difficult to produce the desired finish so the answer is to raise the iron temperature above that of leaded solder and although the solder is still classified as 'multicore fluxed', I now use 'Fluxite' paste in addition and this makes all the difference to the finished joint.
 I am of the opinion that the raised temperature used for multicore lead free solder is just a bit to high for the flux within and burns it off before the joint has cooled, leaving you with rough looking joints.. hence the Fluxite. I simply twist the wire strands together, dip them in the flux and push them through the motor terminals. I dip my multicore solder in the flux also and dab it onto the iron bit to 'wet' it then apply both heat and solder to the joint and hey presto, it all flows together. Remove the heat immediately this happens because if you don't, you will simply burn off the flux and end up with a dry looking lumply joint again.
It all takes longer to say than do of course.
Just as a footnote, I have had this tin of Fluxite for years....... I suppose its' still availabe??
If you are going to solder, get the right kit for the job.....a temperature controlled soldering iron , usually a type up to around 50Watts will do just about anything you need for electrical and electronic work and they come with interchangable bits and a fully variable transformer base station which gives the iron a terperature range of 150degC to 420degC. A good Christmas present??
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HS93 (RIP)

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Re: Soldering - what am I doing wrong?
« Reply #18 on: November 12, 2007, 11:32:50 AM »

I use Isopropyl alcohol I think they call it Denatured alcohol over there. I get a small Paint brush followed by a small brass brush  or if it can be dipped (without damage to othere parts). some people use  Cellulose Thinners.

Peter

Isopropyl alcohol and denatured alcohol are two different things. Denatured is normally ethyl alcohol ( as in booze) with the addition of methyl alcohol - to stop you drinking the good stuff :D

Isopropyl alcohol is used for many cleaning jobs - I first came across it as a young computer operator - we used it to clean the heads on tape drives.

Barrie

  Yes but can they both  be used to clean without leaving a residue ?

Peter
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Re: Soldering - what am I doing wrong?
« Reply #19 on: November 12, 2007, 12:35:43 PM »


     But surely the flux is only there to  chemically clean the areas so the solder will 'wet' the components to be joined?
     Invariably the heat of soldering usually burns off the flux residue, yes i know it's a fine line NOT to overcook the joint,
     but the residue canalso be washed off with - hope no elfins - cellulose thinners or acetone. (Don't let glue sniffers
     read this) ;D
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sheerline

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Re: Soldering - what am I doing wrong?
« Reply #20 on: November 12, 2007, 02:48:22 PM »

Cellulose is good for washing off flux....but beware of surrounding plastics. Iso propyl is also g0od and won't damage plastics but neither product will clean off 'cooked' flux which has turned black due to overheating. Ideally, when the joint has been correctly soldered, you should not have any burnt residue remaining but this ruddy lead free solder rubbish is not as user friendly as the 'proper' leaded stuff. The last time I bought leaded solder was earlier this year, it is/was made by Multicore and came from RS components, their stock number is  554-923, the solder is 1.2mm dia and is about the right size for most jobs. Not sure if it is still available. I still find the addition of Fluxite invaluable in obtaining excellent muck free solder joints even when using this solder. O0
Hope this helps.
Chris
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Admhawk

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Re: Soldering - what am I doing wrong?
« Reply #21 on: November 13, 2007, 12:23:51 AM »

Seems I made a general assumption about rosin core solder. I didn't mean to imply it wasn't any good, I do use it for larger jobs, but the liquid solder works better for me for things of a more delicate nature.

My experience as an electronics technologist and qualified military spec solderer is that any work bench with an industrial sized solder station uses flux and solid solder, no rosin core. However, my experience has been gained in the industrial maintenance fields. It surprises me to hear an electronic board manufacturer uses rosin core solder, but I suppose it shouldn't, there are many ways to do things in this world.

The important thing here is that the original problem in the first post has been taken care of, happy boating!
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