Questions on using solid silver for a soldering iron tip

Thread Starter

Eddy Current

Joined Jan 25, 2017
25
Hi,

Saw this thread: http://forum.allaboutcircuits.com/threads/diy-soldering-iron-tip-the-best-material.105032/

where Alec_t mentions using solid silver as a soldering iron tip. Seems like a really good idea. Highest thermal conductivity, and a noble metal. I have a lathe and mill for shaping the bit, and and the silver is easy and cheap to source (about $2/cm).

My questions:
  • I'm wondering if i need to "treat" the silver, or do anything to it before using it for soldering?
  • Also, is there much difference between 99.9% and 99.99% for this purpose?
  • Any other things I need to be aware of?
Cheers,

Ed
 

Thread Starter

Eddy Current

Joined Jan 25, 2017
25
What do you mean? It will become tarnished? I expect it will be slower than copper, and I can just chuck it in the lathe and polish/sharpen when it gets dirty
 

MrAl

Joined Jun 17, 2014
7,811
Hi,

It will probably work ok but you could test it and then tell the rest of us here :)

Silver is more expensive than copper so it probably was not used for that because of the price as compared to copper when copper has almost the same thermal conductivity. It's like wasting money. The cost is probably a lot more for that extra 1 percent conductivity.

A good question though is will silver erode as bad as copper with various rosin and acid core solders, or even will it erode more.

Since you have the means to create a tip like this you should try it and see how well it compares to just copper.

Long time ago i got tired of buying tips so i went to steel instead of copper. Tip lasts forever. Conduction is a lot less though so you need a shorter tip if you want good heat, but even a longer tip works ok for some things. I made very long thin tips for very small work a long time ago out of brass too. Brass has much less thermal conductivity, but it still worked and the tip lasts forever. Again, making the tip shorter allows better heat with brass too.

I use a special iron these days so tips for that would be harder to make.
 
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Thread Starter

Eddy Current

Joined Jan 25, 2017
25
According to Alec_t it works great :)

When I get around to going to the silver merchant, I will definitely report my findings, but that could be a while, because I also don't do a lot of soldering.

Currently soldering with bare copper, and it is beautiful while it is clean and hasn't pitted. Silver is a noble metal, it is much less reactive than copper. Nitric acid will dissolve it, but aqua regia won't.
 

Tonyr1084

Joined Sep 24, 2015
5,069
I'm probably not the one to give an answer on this subject. My concern is the use of "Silver Solder". This is one way they're getting away from Tin/Lead solders. SS has a higher melting point and requires more heat to flow. I'd be afraid of silver depletion from the tip due to the soldering process. Like I said, I'm not the one to give any kind of definitive answer. So all I'm offering is an observation that may or may not be accurate.

One material DID come across my mind - beryllium copper. Harder than copper, still has a good thermal coefficient. Maybe it would be an even better alternative for an iron. Copper DOES sublime during soldering. That's why copper tips erode fast. I wonder how fast a beryllium copper tip would degrade.
 

Externet

Joined Nov 29, 2005
1,537
Come back with results with silver, am curious.

I did it with gold when the leadfree became mandatory and surprise ! ... the gold dissolves as butter with the tin or whatever in the silver solder alloy. And Ag is not expensive. One ounce = $18 to make many tips.
 

Tonyr1084

Joined Sep 24, 2015
5,069
Little late to tell you this, but gold plated leads (which don't tarnish) WILL make solder brittle. That's the number one reason why they pre-tin the leads. Especially if the leads are gold plated. Google "Gold embrittlement" and see what comes up. It's been a problem in the electronics industry for some time.
 

Thread Starter

Eddy Current

Joined Jan 25, 2017
25
What is your concern specifically regarding depletion? And is this a different process to the copper sublimation you mentioned?

I'm still using Sn-Cu, don't think I have any Sn-Ag-Cu, and definitely not high content silver solder. The iron has no temperature control though, and it is old, I have no idea what it's operating temperature is.

Dunno about beryllium fumes though :) also don't have an easy and cheap source, unlike silver. A 75x5mm pure silver rod is about $15, and I can keep on turning down the tip to a fresh point on my lathe.
 

Tonyr1084

Joined Sep 24, 2015
5,069
I had a nickel plated tip that was made of copper. Eventually the nickel wore out and the solder and flux began eating the copper out of the nickel plated tip fast and furious. It now looks like a tooth with serious decay. The tip is gone and much of the internal copper is gone too. Also, using a copper soldering tip on a Weller soldering gun; those tips erode too. In one afternoon of rewiring a tractor trailer (just the trailer lights part) I went through TWO "Harbor Freight" copper soldering tips.

Now, regarding my expertise on soldering irons - I HAVE NONE! Expertise that is. I only know that a tip made from silver, I SUSPECT would sublime during soldering. Not as fast as solder itself (silver solder) but I'd imagine it will go pretty fast. But like I keep saying - I DON'T KNOW THESE THINGS. I'm only offering a point for consideration. Maybe factual, maybe not. I'm not even positive that my soldering iron tips (professional tips) are nickel. They're shiny metal things that LOOK like nickel.

I have a beryllium copper rod sitting in my cupboard right now. I'm considering throwing it on my drill press and boring a hole down the middle of it then turning it down to the same size as my good tips, then turn the end down till it forms a typical solder iron tip. Maybe. Maybe not. I'm just a little curious now since this subject has been broached.
 

#12

Joined Nov 30, 2010
18,210
Silver and mercury are used to make dental fillings. Therefore, silver can form an amalgam.
Copper dissolves in solder. I'll bet silver also dissolves in solder.
Please let us know how this turns out.
 

ian field

Joined Oct 27, 2012
6,539
Hi,

Saw this thread: http://forum.allaboutcircuits.com/threads/diy-soldering-iron-tip-the-best-material.105032/

where Alec_t mentions using solid silver as a soldering iron tip. Seems like a really good idea. Highest thermal conductivity, and a noble metal. I have a lathe and mill for shaping the bit, and and the silver is easy and cheap to source (about $2/cm).

My questions:
  • I'm wondering if i need to "treat" the silver, or do anything to it before using it for soldering?
  • Also, is there much difference between 99.9% and 99.99% for this purpose?
  • Any other things I need to be aware of?
Cheers,

Ed
Silver has excellent thermal conductivity - I even heard of someone machining a motorcycle cylinder head out of a block of silver for a high stakes competition event.

I would expect silver to alloy into the solder, probably even faster than copper. You could have it iron plated just like they do with copper bits, but its going to be an expensive item to bin when the plating gives up.

A smear of heatsink thermal paste between the bit and element can give a worthwhile increase in thermal conductivity, and as long as you don't over do it, there's some protection against burnt flux residue seizing the bit in.
 

ian field

Joined Oct 27, 2012
6,539
I have had excellent results with "iron-clad" soldering tips. I think I ruined one in 20 years.
At that rate, an ounce of silver is a lifetime supply.
Generalising is unwise.

In the past, my irons have led a hard life and short endurance of the iron plating wasn't too much of a surprise.

The quality of plating can vary enormously - some cheap irons only have plating on the circumference of the bit.

The Antex irons I've settled on are at least satisfactory, the 50W TC Antex has the original bit after over a decade - but I'll admit the iron leads a quieter life than it used to.

I gave up on Weller when a brand new element was wrecked by flaky plating on the bit that goes inside the element tube - the plating there doesn't even see any work.
 

shortbus

Joined Sep 30, 2009
7,940
I must be missing something in all of this. No matter what the tip is made of, it is still the irons element that makes the heat. Once the tip gets to that temperature, the elements temperature, how is the material the tip is made of going to make the solder work better? Since most quality irons use an iron/steel plated tip, why not just make a DIY tip from steel in the first place? No matter what material the tip is made of, it's the "tinned" layer that is actually touching both the work and the solder.

I'm sure some one will tell me where I'm wrong about this. Like #12 I have an old soldering iron that was used for more years than I can remember and never had to change the tip, because it's iron plated copper and I clean and re-tin it before putting it away. And it is just a cheap little Radio Shack one.
 

#12

Joined Nov 30, 2010
18,210
I must be missing something in all of this.
This whole conversation probably isn't worth much.

Silver has one of the fastest travel times for heat. If there is a large thermal mass behind the tip, the silver can move that heat to the front of the tip faster than most other metals...but who ever said there is a significant thermal mass behind the tip?
 
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GopherT

Joined Nov 23, 2012
8,012
I think, for less than $10 of silver, it is an interesting experiment. And, @Alec_t already has proven that it works for 100 joints (one 4x6 pcb gets about 100 holes in my designs). What's needed now, is the durability testing and a clear benefit. If a lifetime durability is the benefit, it could be interesting. I don't think high thermal conductivity is a selling point - I've never been short on heat carrying capacity. The promise of long life could be most interesting to me. Is there more?

How could the lifetime be tested?

Any other issues? Like tarnish (silver oxide) causing solder to bead up on the component lead or pcb instead of wetting it and bonding.
 
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