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The friendly folks over at the Weller blog posted a great article today explaining what’s inside a soldering tip — and why.  Something I was surprised to learn: while copper conducts heat well, it doesn’t do so well holding up against tin — hence the layer of iron around the copper tip.  It seems as though the iron layer is the main factor determining the longevity of a tip.

If you spend any time at all with an iron in your hand, this is a must read.

The Architecture of a Soldering Tip [Weller Blog]


6 Responses to What’s Inside A Soldering Iron Tip?

  1. Well THAT explains why my attempts to reshape tips never turn out too well! Darn things won’t hold a tinning for anything…

    Now, to figure out how to iron-plate things!

  2. Brau says:

    That is interesting and explains why when the tips go they often develop a hole right down the middle. They didn’t say why the chromium was plated on it though. I’ll have to assume it prevents oxidization of the non-wetted iron plating.

  3. John Laur says:

    >They didn’t say why the chromium was plated on it though

    You may have heard chromium doped iron referred to more commonly as “stainless steel”. They do it because they have to iron plate the whole thing and they might as well not allow the iron to rust up where the tip won’t be tinned anyway.

    My buddy is the IT director for the company who makes a great deal of soldering tips (including most of Weller’s product line) at their factory in Costa Rica. It amazed me to know that they make some soldering tips as big as your fist for industrial use! If anyone has any specific technical questions about the tip manufacturing, I can probably pass them along and get you an answer.

  4. ned.ludd says:

    Solder doesn’t stick to chromium plating. The iron plated tip is what’s designed to be tinned.

  5. John Laur says:

    OK after exchanging a few emails it seems that I misunderstood some things; The tips made down at that factory in Costa Rica (by Plato: owned by TechSpray: owned by ITW) are not made for or purchased by Weller (owned by Cooper); however they do produce tips that are compatible with Weller equipment as well as tips compatible with other brands and custom tips for industry.

    Sorry; didn’t mean to cause a diplomatic incident! Solder tips are apparently a lot bigger business that I’d ever imagined… but after seeing the factory where they weave, coat, measure and package the de-soldering braid, I’m not surprised. I’ve maybe ever used 25 feet of the stuff in my whole life and they practically measure output in MILES PER HOUR when making it!

    For what it’s worth it’s remains factual that they produce solder tips as big as your fist which can no doubt be used only for for evil and nefarious purposes (and I guess making boats and things of that nature).

  6. Mistermetcal says:

    There are reasons behnd the layers of plating on your soldering tip. But, first lets start with the copper base. Copper is easy to machine and it transfers heat very well, but as mentioned it will not last very long when exposed to solders. So on top of the copper an Iron plating is added, this is where the tips life comes from. Tips with thin iron plating have a short life, tips with a thick iron plating have a longer life. But, too much iron plating and the tip performs poorly in the thermal transfer department. So the manufacturer has to balance performance vs. tip life.
    Now, since Iron rusts, the manufacturer has to apply a Chrome plating over the tip in the areas where NO soldering is to occur, this protects the Iron plate and provides the user with a cosmetically acceptable tip.
    One reader mentioned that solder does not wet to Chrome, exactly so this Chrome also eliminates solder creeping up to the heater. Since the solder will not wet to the Chrome, before shipping the tips, a layer of solder is tinned to the tip on the working surfaces of the tip. This tinning ensures the tip does NOT oxidize during shipping and that it arrives at your bench ready to use.
    You should also note that most soldering tips are factory tinned with lead free solder to meet international requirements.

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