Why is my soldering so bad?!

  1. waddycall

    waddycall Member

    Messages:
    1,102
    United Kingdom
    I’ve recently had a steep learning curve with soldering. I had been letting the iron get dirty and overheat burning the tip. I now keep the tip clean using a damp sponge and occasionally clean the tip right off and re-tin it by wrapping flux core solder around the tip when it’s cold and then turning the iron on.
    If the tip isn’t tinned (covered in nice shiny solder) you won’t get quick heat transfer and end up cooking stuff like I was.
     
    Last edited: May 22, 2020 at 9:37 PM
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  2. Parm

    Parm We Will Do Whatever It Takes

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    Same here, just use solder and job done
     
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  3. Gwil Member

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    Portugal
    I am overly familiar with that 'dull lead' look......

    Seriously, lots of expert advice which I will be trying out shortly. Gotta keep on keeping on.
     
  4. dobbslc

    dobbslc Forum Supporter

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    It might be worth changing the solder you have, it could just be crap or have no flux in it.
     
  5. The_Yellow_Ardvark

    The_Yellow_Ardvark Member

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    Some core flux solder can dry out into had lumps and makes it all but useless.
     
  6. Maker

    Maker nEw mEmBeR

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    Don't ask questions
    What tip are you using? Cheap irons always seem to come with a blunt point, like a biro. No idea what they're for but it's not soldering! The "bevel" type are much better, I use them for everything.
    [​IMG]
    The "440" on the far right is the only one I'd ever use, a sharp point makes sense for fine SMD work and a bigger bevel might be useful for thick wires, everything else is fairly useless imo. I machine my own tips from copper bar and conveniently, a bevel is the easiest to make. :D
     
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  7. MCKDAVID Member

    electrical solder has changed over the years to lead free, doesn't flow as well in my opinon, but certainly better for the health of the employees using it every day.
     
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  8. 8ob

    8ob Forum Supporter

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    On anything that can be washed off I am with @mtt.tr and use an active flux (I use everflux), cant see it being any more corrosive than the Bakers fluid of old. For small electrical jobs I have found the fluxed core solders more than adequate, not so sure about the residue on that stuff or whether it should be cleaned off .

    Bob
     
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  9. MetalMonkey Member

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    281
    Location:
    UK
    The flux in the solder is OK for small joints, tinning wire etc, but additional flux does really help on larger components, especially on SMD or where you are reworking a joint.
    Get a good iron with a small tip, I prefer angle tips to chisel and most importantly, good quality solder. A lot of the cheap solder is recycled rubbish in dubious mixes that just won't give you a good joint no matter what you do.
    Keep the tip clean, I usually wet mine with solder and then wipe the solder off before starting a joint to ensure it is spotless. Don't bother with those hopeless wet sponges, get a brass wool cleaner thing, much better.

    The rest is a steady hand and practice.

    Oh and lead free will always look a bit dull, that is normal.
     
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  10. Gwil Member

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    566
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    Ok, I now have a shopping list, and have binned my Chinese iron! My tools, materials and technique all need to be seriously rebooted.

    Thanks everyone.
     
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  11. arther dailey Member

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    3,730
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    Southampton England
    one thing to remember is most sheathed copper wire when stripped also has a light varnish on the wire, clean this off and tin first , often pays to strip off more sheath than you need clean and tin , then cut the tinned wire to the length you need and solder to joint.
     
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  12. eSCHEn

    eSCHEn Bit Wrangler Staff Member

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    You don’t need spend a lot of money to get a decent iron Gwil. I can thoroughly recommended the T12 knockoff from Banggood et al. Review at https://www.mig-welding.co.uk/forum/threads/t12-soldering-iron.95188/.
     
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  13. bricol Member

    Messages:
    959
    N.Yorks, UK
    Before the bin men come for that Chinese iron, try it again.

    Tin the wires first - small amount of solder melted on tip, apply tip to wire - the molten solder will allow heat conduction to the wire better. Add solder to the wire from the other side - melt the solder into the wire, not the iron. When its flowed into the strands, remove solder and iron. Do the other other wire(s). Trim to suitable joint length if needed - bigger wires, a longer overlap, smaller wires, shorter overlap.

    Bring wires together - now when I was younger, I seemed to be able to do this without wobbling, and I could see what I was doing. Now I use something to hold at least one of the wires, and occasionally a magnifying lens on a stand if the wires or components are small. Small blob of molten solder on the iron, bring wires together, touch the iron - the blob aids heat transfer, the tinning on the wires melt, the solder runs together, the joint is made - very rarely do I have to add more solder. Remove the iron, hold steady for the few seconds for the solder to solidify. Done.

    If you have interchangeable tips, then use a tip suitable for the wire or component size - small tips for small, bigger for larger. Larger wires and components drag the heat out the tip and your're left trying to heat it up - the heat sinks away down the wire and you end up with melted insulation too. Soldering a wire into an eyelet or similar things - tin both, probably wire first, eyelet second, as the eyelet keeps the heat so when you come to bring them together and reapply heat to the eyelet first to melt the tinning again, it takes less time - bring the wire into the molten solder in the eyelet so it melts the wire tinning . . . apply more solder if needed, to the molten puddle, not the iron tip. Hold still until it cools - usually the solder dulling and bit more is enough.

    Very rarely use extra flux - probably when soldering dirty old wires in cars - clean the corrosion off with a scotchbrite pads, apply flux and tin as well as possible. I try to avoid soldering many wires in cars unless it's straight wire to wire in-line oing - to add connectors etc. Mates wo worked for Lucas producing fighter jet wiring looms told me the solder wicks down the wire and the wire will fracture from vibration at the end of the solder - crimp terminals instead. So if it's good enough for them, it;s good enough for me. If I have to solder, I will had heatshrink to support the wire for a half inch or so.

    That's worked for me with my dads Weller 25W iron when I was kid until the tip burnt away soldering tiny wires in radio control units for racing model cars, to the bigger wires for battery packs and motor connections (I still use a radio transmitter I modified to add servo reversing switches over 35 ys ago), small 15W irons on delicate components, 100W Draper gun, 150W wooden handled massive copper tip, takes half and hour to warm up, fabric corded iron my dad had and my current temp controlled Circuit City iron - which more than likely is simply left on full welly all the time. I didn't have quite so much success with the big copper one heated in the cooker gas flame though :)

    Biggest mistake I think people make is to melt the solder on the iron, while not having the actual wire or component hot enough - the solder has to melt into/on to the wire to work.
     
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  14. anjum Member

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    1,150
    Location:
    London UK
    Get some tip cleaner. It comes in a little tin which you push the hot iron tip into and wipe off on a wet soldering sponge or bit of folded up kitchen paper if you are tight like me
    Then tin the tip and solder as above
     
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  15. Hopefuldave Intergalactic pot-mender

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    The Shed of Danger, surrey, England
    Not only doesn't flow as well, it creeps when hot / under stress so it has a shorter reliable lifespan - there's a reason aviation, military, medical and other "life critical" devices are exempt from the lead-free requirement. If employees are using it every day (i.e. soldering at a bench) they should have fume extraction anyway, the colophony in resin flux is a known asthma sensitiser.

    Dave H. (the other one)
     
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  16. anjum Member

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    1,150
    Location:
    London UK
    Last edited: May 23, 2020 at 4:06 PM
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  17. Gwil Member

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    566
    Location:
    Portugal
    Almost a workshop manual! Thanks, I do think I'm guilty of the last point in particular. Often it's because the tip is as big as the item (so wrong tip) and there's no room to play with, so the solder melts on the iron while the work is comparatively cold.

    I also use crimps and heat shrink where possible, and my boat electrics never had a failure, or the bikes I've rebuilt. I was advised by a sparks years ago never to solder joints where vibration was present if at all possible. Sometimes though it's the only choice.
     
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  18. anjum Member

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    1,150
    Location:
    London UK
    Where joints are prone to vibration them some sort of stress relief should be used. Hook joints with lacing and glue to pcb's etc. Fairly obvious if you think about the joint as a weight in the centre of a string.
    I used to teach Mil-217e to solder operatives it or it's latest replacement is the ultimate guide to wiring and soldering. A bit OTT for most use but cars are pretty hostile environments.
     
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  19. bricol Member

    Messages:
    959
    N.Yorks, UK
    I'm a mechanical design engineer (who can swing whatever tool is needed most of the time, so I tend to get listened to on the shop floor) but had an interest in electronics when younger. A school mate, (infact still a mate now) was much more into it and went on into electronics design etc told me I was doing it wrong - always melting to the wire, not the iron. My soldering improved immediately.

    I trial cars - completely rewired the current one when I got it - a lot abuse, with damp, dirt and vibration - over a decade of abuse and no wiring problems (yet!)
     
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  20. sako243

    sako243 Member

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    Location:
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    Not usually required and in some cases really it's to be avoided. Previous job we built a lot of extremely high end SDRs and the process of cleaning the PCB caused more harm than good when it came to RF performance. Rework had to be done neatly to eliminate the need for cleaning.

    See above, if it's done nearly in the first instance shouldn't need it.

    @anjum's post covers it, in applications where a lot of vibration is used then strain relief should be provided. A well done solder joint should outlast a crimped one but it's more difficult to get right, especially in a production line. An bad crimp is far worse from experience. The main reason crimping took over was efficiency and speed on the production line. The proper crimp should guarantee consistent results.

    I've had more involvement in automotive, military and space based electronics than most and there's never been a real difference between soldered and crimped. We choose a connector based off application and go with it be it soldered or crimped or both.
     
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