DIY Soldering iron tip... The best material?

Discussion in 'General Electronics Chat' started by FallknivenF1, Dec 27, 2014.

  1. FallknivenF1

    Thread Starter New Member

    Dec 27, 2014
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    Hi all, my first post here so i hope it's okay :D

    Anyways. I've only recently got into the hobby of hi-fi repair, and have sourced a relatively decent 40 watt Weller temp control station to start out with. The only issue so far is that the stock Weller tips seem to degrade surprisingly quickly even with the best of care :eek:. This has led me to take interest in going down the DIY route, so i need to ask...

    What is the best material for a DIY tip used at around 380 degrees celcius? I understand Copper is favorable for it's thermal conductivity but also it will degrade even faster, steel and iron will prove to be more durable but i doubt the performance will be astounding. How would Brass, Aluminium and bronze behave?

    Would love to hear your opinions and possibly your experience on this matter, it would be a huge help. :)

    - Jordan
     
  2. #12

    Expert

    Nov 30, 2010
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    What? Doesn't Weller sell Ironclad tips for that one, or does the lead free solder eat through iron? And what amount of time is surprising? Most of us get years out of a Weller brand Ironclad soldering tip.
     
  3. takao21203

    Distinguished Member

    Apr 28, 2012
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    It took me years to ruin the original tips from the soldering station, by piercing, and mostly by overheating.

    Now I got new one's, from 2 sellers, still using the first one (it developed kind of a crack from overheating, but the tip area is still intact)

    Aluminium tip, great idea.

    Bronze also not bad the tin will dissolve the copper.

    380C is a bit high temperature, for lead solder 200C is enough, while tin based also only needs 260C.

    Melting point is even lower.
     
  4. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    Buy the genuine weller tips from digikey.com for $6 or $8 each.
     
  5. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    Welcome to the forum!
    'Fraid not, Takao. Have you ever tried tinning ali using normal solder?

    My 15W iron currently has a solid silver tip ~2mm square section. No probs so far.
     
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  6. takao21203

    Distinguished Member

    Apr 28, 2012
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    Real silver? Maybe gold or platin would last a long time- if it isnt dissolved, only problem is the price.
     
  7. #12

    Expert

    Nov 30, 2010
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    I'm afraid gold will make an amalgam (and be dissolved) and platinum can not be tinned.

    Gopher should know the answer to this one.
     
  8. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    Yes. A couple of $/£ gets you a few inches/cm of small-section rod/wire/bar from jewellers/craft suppliers. You can force fit the silver into the drilled end of a worn-out normal bit.
     
  9. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    I usually assume the companies that have been doing it for years know best.

    Kester - a big producer of solder claims that lead free solder eats tips. A tin/lead solder will let a tip last 3. Of this while a tin free solder will eat the tip in 3 weeks. Shortened life is mainly from the higher operating temp - not corrosiveness of solder. Kester does not offer a tip material recommendation.

    Weller, a big name in soldering irons and tips, only states that their copper core tips are iron plated (industry standard) that are thin plated with nickel and chromium and pre-tinned with lead-free solder.

    Page 4 here
    http://www.kester.com/kester-content/uploads/2013/06/Lead-free-Handsoldering.Final_.4.19.06.pdf

    Weller has a good summary of how to extend the tip life
    - use the lowest possible temp possible
    - clean the tip (sponge is ok, metal wool is better - see link below
    - user must re-tin immediately after sponge or metal wool cleaning of tip (before setting it back in stand or soldering). This keeps the oxygen off of the steel
    WELLER PRESENTATION TO SALES REPS - LEAD FREE SOLDERING
    http://www.elexp.com/Images/Weller_Coping_with_Lead_Free.pdf

    Since it is very difficult (impossible?) to plate true alloys - just because electro-chemistry doesn't work that way- we are stuck with elemental metals.

    A platinum or gold plated tip may seem inert to solder, it is likely going to be so thin to make it cheap that it will wear quickly when actually soldering (abrasion and subsequent oxidation of metals below the surface). Therefore, we are stuck with iron/nickel/chromium.

    I would avoid lead-free if possible.
     
  10. tcmtech

    Well-Known Member

    Nov 4, 2013
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    Most any heavy masonry nail or screw once ground down to a point and fitted in a gun tends to work very well and never wears out.;)

    Granted it may not be as thermally conductive as copper but you are working with a pretty short stout piece so it's not really a problem.
     
  11. ian field

    Distinguished Member

    Oct 27, 2012
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    A company I used to work for, that made ultrasonic cleaning and plastic welding equipment - also (occasionally) made an ultrasonic solder dip for tinning aluminium parts.

    Apparently - you can solder aluminium sheet by heating it from underneath, melt a blob of solder on top and scour the oxide layer from within the blob, using a glass-fibre brush.

    If you make a soldering tip of aluminium and tin it with the special solder for aluminium - you will then be able to carry on using it with ordinary solder.
     
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  12. #12

    Expert

    Nov 30, 2010
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    @GopherT , please address these questions: Will gold be dissolved in solder? Will platinum refuse to be wetted by solder?
     
  13. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    Learn something new every day...
    Gold does dissolve into tin solders. Gold plated leads on transistors & solid gold binding wires wet out well then for inter metallics (alloys) of tin and gold.

    Another big producer of specialty solders - copper or gold leads to the silicon chip type of solder is indium corporation. Here is a blurb from them on gold...
    http://blogs.indium.com/blog/eric-bastow/intermetallics

    I don't know about platinum at low temperatures. Molten metals is normally not a common thing in the chemistry lab but, surprisingly, it has been a big part of my job in the past 3 years. I'll look into it.
     
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  14. #12

    Expert

    Nov 30, 2010
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    At least I guessed the gold part correctly. :p

    Au would make a miserable soldering tip because it would be eroded even quicker than copper.
     
    Last edited: Dec 28, 2014
    GopherT likes this.
  15. FallknivenF1

    Thread Starter New Member

    Dec 27, 2014
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    Hi everyone, thanks for all the replies. So it would seem Ali and Steel/iron is a no go from what you are saying. I guess it's factory replacements for me then, I'll switch to tin/lead solder as you advise and see how I get on.

    - Jordan
     
  16. ian field

    Distinguished Member

    Oct 27, 2012
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    Iron is used - but its a poor heat conductor, so its plated onto a copper core to prevent the copper alloying and dispersing into the solder joints.
     
  17. MrAl

    Well-Known Member

    Jun 17, 2014
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    Hi,

    The total thermal resistance is related to the length of the object and it's cross sectional area. The resistance goes up as the length increases and goes down as the cross sectional area goes up. This means a long tip will not solder as well as a short tip, and a very thick metal tip will solder better than a thin tip.

    While also looking at the thermal properties of several metals, we find that iron and steel are about 8 times less thermally conductive than copper. This is not very good at all. This means to get the same soldering ability from a steel tip as a copper tip we'd need a tip that is either:
    1. 2.83 times the diameter as the copper tip, or
    2. 8 times shorter than the copper tip, or
    3. 2 times shorter and 2 times the diameter as the copper tip.

    Using #3, a tip half the length and twice the diameter will mean the steel tip will solder about as well as the copper tip. So a 1.5 inch long 1/8 inch diameter copper tip is about the same as a 0.75 inch long 1/4 inch diameter steel tip.

    Now we turn to the forgotten metal alloy, Brass...

    Common brass has thermal resistivity about 4 times that of copper, so it's about twice better than steel or iron to begin with.

    To get the same characteristics as that of copper, we could use a tip made of brass that is the same length as the copper tip but has twice the diameter. If we use the same tip diameter we'd have to shorten the tip by four times, so a thicker tip works better.
    If we choose to shorten the tip by 25 percent we can get by with a tip diameter of 1.73 times the copper tip diameter. Shortening the tip by 25 percent means a 1 inch tip turns into a 3/4 inch tip for example.

    So the best bets here are:
    1. Steel, 2 times shorter and 2 times the diameter, or
    2. Brass, same length as copper tip with 2 times the diameter, or 0.75 times the length of the copper tip and 1.7 times the diameter of the copper tip.

    Just to note, i've used brass for my tips for a long time. The main thing to remember is that it either has to be much shorter than the original copper tip or of greater diameter. If the tip screws in then the larger diameter has to be turned down first to the right diameter for the screw threads.
    Hobby stores sell short lengths of brass stock, as well as some hardware stores, which are made of common brass.
    I've also used regular soft steel 10 penny nails in a pinch, but they are not as good as brass. They do tap for screw threads easily though, and so does the brass.

    Just to note, using a tip that is too long or not thick enough can result in cold solder joints. It's not too hard to test a newly created tip though, just try to solder with it and see if it solders the same as with the copper tip. It should melt the solder just as fast and wet the joint just as well when soldering a typical joint.

    Also, line voltage can dip sometimes which causes the iron itself to cool a little bit. Try to make sure you get the right line voltage for the iron. Keep in mind that a 10 percent drop in line voltage results in a 20 percent reduction in heating power.
     
    Last edited: Jan 1, 2015
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