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What Are All The Clues On Soldering Irons?

Discussion in 'Electronics & Electrics' started by abrogard, Jan 16, 2019.

  1. abrogard

    abrogard Member

    Jul 8, 2009
    murray bridge. s.a.
    I bought a new iron - 60W - because none of mine seemed hot enough. Just a little old fashioned rugged electronic organ amp board to work on.

    Now I find it won't tin the tip.

    And makes a dubious job of soldering a component in and I think it is because of that.

    Generally heat gets transferred from the tip into the job via the solder on the tip, that's what I've always thought. So if it won't tin and there's no solder on it you're beat before you start.

    And though it gets hotter in the hand than any iron I've ever had the tip seems very cool. Nothing's happening on the board. When unsoldering the solder isn't melting.

    But it is also the most pointed tip I've ever had. It'd seem to me perhaps pointed tips transfer less heat than a wider tip would. Yes? No?

    So I google for help/info and I find people saying 'file the tip', and others saying 'never file the tip' and some saying 'scratch the tip' and others saying 'don't', and some saying use baker's flux on it and others saying 'never use Bakers flux.. it's plumbers flux, it'll kill your board' and some saying use on 1mm flux cored and others saying use 3.2mm flux cored and some saying don't use flux cored, use flux and solder...

    And some saying that's a bad iron. Some irons are just bad. And some saying that's a bad tip - tips are specially cleverly made, not just lumps of iron and that tip ain't.

    and that's without getting into the heat of the thing.

    or the tip shape.

    Anyone got all the clues so's I can get up to speed in a hurry? I've got four trannies to solder in and the quicker the better.

    Last edited: Jan 16, 2019
  2. goldpenis

    goldpenis Member

    Jan 19, 2002
    Your tip is probably oxidised and requires a clean. From memory, the selected tip should be 2/3rds the width of the pad/item you're trying to solder; any less and you will most likely not get enough heat or dwell on the pad and cause damage. Any more and you cause damage to the area external to the pad.
    Last edited: Jan 16, 2019
  3. aXis

    aXis Member

    Jun 27, 2001
    Kalgoorlie, WA
    Some tips are coated and you shouldn't file those as you'll never be able to re-tin them. If there's no coating then file away and try to tin it again.

    Personally I find the pointed tips nearly useless, they have way too small a surface area. I prefer the angled flat face here - https://www.hakko.com/english/tip_selection/type_bc_c.html
    Us as big a tip as you can handle based on the sensitivity of the job as it will keep it's heat longer.

    You only need a small amount of solder (or none) on the tip. The tip should contact the work-piece and heat it up, then you introduce the solder to the work-piece. The flux then goes right on the job (not the iron) and the solder will wet properly.

    Check if you have lead free solder or not. I had real trouble with it - it needs much hotter temperatures, crystalises too easy and oxidises fast. I ended up going back to lead based and it's heaps better.
    Personally I like fine 1mm flux cored solder - it melts easier and allows more control on fine work. It works OK on larger jobs too, you'll just have to use more.
  4. Technics

    Technics Member

    Apr 29, 2002
    Brisbane, AU
    That's a lot to take in. The difference in opinion you have read on things like the type of solder could be explained by the different applications of soldering from tiny SMD components to heavy gauge wiring and obviously people's different personal preferences. Most tips are copper but plated with iron, nickel (sometimes) and chrome. This is to prevent oxidation and to allow solder to stick but prevent it from slowly eroding the copper core. If you damage the plating then the copper will start to dissolve into the molten solder on the tip.

    You are correct in what you say about pointed tips. There are other factors that affect heat transfer but that is certainly one of them. Ideally, on a new soldering iron the tip should be pre-tinned but in some cases they rely on the plating to prevent oxidation of the tip before the iron gets to the customer. That sounds like the case here. In all likelihood some oxidation has occurred despite this plating and the flux in the solder you are using is not aggressive enough to remove it. In this case, short of returning the iron you can try to remove this oxidation. The reason bakers flux is not recommended is because the acids it contains can corrode the components and traces on PCBs. It might be possible to try it just to clean the tip, followed by careful cleaning and tinning with a proper solder suitable for electronics. This should probably be done several times to ensure as much of the acid flux is removed as possible. There are special tip cleaner/tinners you can use (https://www.kitronik.co.uk/blog/clean-maintain-soldering-iron/). They are a mix of solder and a more aggressive flux. The other option is to use something abrasive to remove the oxide. However not so abrasive as to remove the plating. Some irons come with a stand (or you can buy one I.e https://www.jaycar.com.au/goot-soldering-iron-tip-cleaner/p/TS1510
    ) with a special brass wool designed for cleaning the tip. This is designed to replace the old wet sponge and is supposedly less damaging and causes less of a temperature drop. If you get one of those it might help. You could try sandpaper but it should be fine grit, you should go easy and you do risk damaging the plating so it should be considered a last resort. If you do cut through the plating the tip will still take quite a while to dissolve anyway so it's not like you won't be able to do anything. It will just need replacement much sooner than it otherwise would. Filing will definitely damage the plating. Once the plating is damaged you will need to file it every now and then to get the tip back into shape. Eventually it will be too short to use.

    Edit: As a final note. The plating on a lot of cheap soldering irons (and some expensive one. I'm looking at you Weller) will fail if you just happen to look at them the wrong way. If your iron is a low cost type I wouldn't be too precious about it.
    Last edited: Jan 16, 2019
    BiggusDickus likes this.
  5. Matthew kane

    Matthew kane Member

    Jan 27, 2014
    If you file or sand down the plating on the tip, it cannot be re-tinned without further damage. Once the core alloy of the tip is exposed, solder will eat away and leave pit holes in the tip over time.
  6. power

    power Member

    Apr 20, 2002
    link to the iron you bought? what type of jobs are you planning on doing?
  7. alan beads

    alan beads New Member

    Jan 24, 2019
    Last time I had this issue it was the cheap chinese solder I was using, new roll from jaycar sorted it out

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