# Solder recommendation



## Robes (Jan 5, 2011)

I am going to put this in the O gauge section,... because I am working on O gauge. Come to think of it, my next three projects are O-gauge. I am heading into town next week for a grain run and thought I would stop by and pick up some contact cleaner. Starting thinking about it and the solder I have is VERY old stuff and probably not the right kind to be using on model trains. Can anyone recommend a solder to use on O gauge? Would it still be the same stuff to use on HO?


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## rzw0wr (Aug 28, 2013)

I use solid core solder.
Very small diameter, .020 and .032.
I use it with a non acid flux.

I have seen that some on here recommend resin core solder.
That works OK also.

Just about any solder but acid core.

For O scale 1/16" solder may be OK.


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## Dave Farquhar (Feb 20, 2013)

The mixture of the alloy makes a difference too. Radio Shack sells a 63/37 solder that has a nice low melting point that makes it easy to work with. You may be able to find that alloy in a hardware store too. Radio Shack also has a solder tip cleaning/tinning solution. It's expensive (about $10) but lasts a long time and makes soldering easier. I think it's worth it for the frustration it saves.


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## Dave Sams (Nov 24, 2010)

This is what I use.

.062 is a little large, but then, you don't have to use too much of it.

I use the paste when I have to re heat a connection, or where I have old work.


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## Lynn D Bennett (Jul 27, 2013)

63/37 is the eutectic mix of lead/tin for the lowest melting point of solder. 60/40 is pretty close and the melting point is not that much more elevated. No matter what there has to be rosin either painted onto the join or it has to be in the solder. Having the rosin in the core of the solder makes for easier soldering.

What ever you do DO NOT use any acid core solder on anything electric or electronic. That solder is for sheet metal soldering.

Also don't use solder for copper plumbing as its melting point is very much hotter than 63/40. In fact it has little to no lead in it and is mostly tin. It does not flow well either.

I have a various sized tips for my soldering station and use the two different sized rosin core solders Radio Shack normally carries. Keep the tip clean and tinned for best results.

LDBennett


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## gunrunnerjohn (Nov 10, 2010)

Either of the ones that Lynn mentioned work fine. I'd buy it in rosin core and forgo any extra flux, I've soldered a ton of stuff and I don't ever feel the need for added flux.


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## daveh219 (Sep 16, 2012)

I have found myself soldering more lately in repairing my PW AF stuff. I also found that using flux on a newly piece of cut wiring works great when attaching it to another piece of wire or solder joint. I have also gotten comfortable using the smaller diameter solder. Easier to get into small places.


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## Lynn D Bennett (Jul 27, 2013)

When I worked in aerospace my department had a assembly line for PC cards using production assemblers but hand soldering (the factory used a wave solder machine for production). The girls used both rosin core solder and liquid rosin on every joint they soldered. Each solder joint was inspected by a Quality Control Inspector with a microscope. Those girls made very good solder joints.

They used a soldering station with a temperature controlled soldering iron tip. I bought that exact one for my son some 20 years ago and he still uses it today on his RC cars. The connections to the motor are huge wires soldered to tiny posts. Anyone that uses his soldering station raves about how good it works. That, I'm sure, is part of why the assembly girls did such good soldering. I have a modern Radio Shack soldering station that is OK but his 20+ year old soldering station does a better job of temperature control on parts that soak up heat.

So there is something to having a good soldering station and using liquid rosin but I'll admit I rarely use the liquid rosin for soldering on end terminals on wires.

LDBennett


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## sjm9911 (Dec 20, 2012)

I use the smaller diameter solder for electronics, I have no clue what' in it. I use flux out of habit. I will say the soldering iron/ gun makes a difference. I use a portable butane fueled iron. Works so much better then the cheap electric one I had. High heat melts the solder fast. And not the plastic components ( don't ask how I know that)! Live and learn.


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## Don Trinko (Oct 23, 2012)

For electrical rosin core is the standard. I prefer the flux built into the solder. Don


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## BigAl56 (Dec 14, 2011)

For soldering wires to track I use solid core solder with flux found in the plumbing section.


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## Lynn D Bennett (Jul 27, 2013)

BigAl56:

There is a risk that you are using Acid rather than Rosin flux. Plumbing flux is probably optimized for the no-lead solder now mandated for plumbing rather than anything we need for model railroading.

LDBennett


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## gunrunnerjohn (Nov 10, 2010)

I've never had any issue soldering to track with my Weller 100/140 iron and rosin core 60/40 solder. I clean the track area and tin the wire. Apply heat and a bit of solder, solid connection.


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## Robes (Jan 5, 2011)

I had to go look up "tinning". Something learned.....


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## raleets (Jan 2, 2011)

I started soldering wires together as a teenager when I had speakers in just about every room in the house that were hooked up to my "low-fi" stereo system. My Mom and Dad were scared stiff that I was going to burn down the house with "all those electric wires". 
No matter what I said they just wouldn't believe there was no electricity flowing in the speaker wires. 
They were always looking around for a way to unplug those wires. hwell:
Bob


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## Dave Sams (Nov 24, 2010)

Robes said:


> I had to go look up "tinning". Something learned.....


Sometimes, when I need a 3rd hand, I'll tin two wires, then apply a little flux, hold one parallel to the other and apply the heat.

The flux makes the solder flow, and the tinning provides enough solder to make the connection.


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## Dave Sams (Nov 24, 2010)

Plumbing flux can be corrosive and conductive. That is why rosin flux is recommended for electrical work.

I used plumbing flux for years, even though I knew better.

Here is a connection made 15 years ago with plumbing flux.









Notice the rust.

I find rosin flux provides a much better heat transfer and flow than acid flux. 

I have used both extensively.

BTW, on occasion, I will put some rosin flux on on old connection and apply the heat.

Magic!


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## trains galore (Jul 22, 2013)

If you mean for electical work on your locomotive, go for 60/40. It's the best stuff for delicate electronics I've found, and all I've ever really needed for wiring and PCBS
Just make sure the tip of your iron is shiny silver (wipe it, add a touch of solder) and you'll be fine! Just be sure to keep wiping the tip intermittently and be wary of burning insulation onto it when soldering wires. Less is more when it comes to soldering, you only need a tiny bit of solder, and the trick is heat (the contact) then apply, and let the solder flow around the joint. There are loads of good sites on the internet on how to solder well, and if you can find some old circuit boards to practice on it is a very good idea
Certainly NEVER use acid core/ plumber's solder on anything electronic, you are bound to cause damage and it is meant for soldering copper pipes, NOT for delicate electrical terminals/ wiring
Good luck!


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## underthetire (Jun 6, 2013)

If you can find 60/40, then yes thats the one, however all the new stuff I see is 63/37, supposed to be more "friendly" or something. Its still works well though.

Sent from my G-Tab Quantum using Tapatalk


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## Lynn D Bennett (Jul 27, 2013)

underthetire:

In an earlier part of this thread I said:

*"63/37 is the eutectic mix of lead/tin for the lowest melting point of solder. 60/40 is pretty close and the melting point is not that much more elevated."
*

In metallurgy the eutectic point in a phase diagram (diagram of the different crystal structures of different mixtures of the metals) is the mixture of metals that result in the lowest melting point. 63/37 solder melts at the lowest temperature of any mixture of solder. 60/40 would melt at a slightly higher temperature. Either is acceptable for electronics and as a user you probably could not tell the difference.

Wikipedia puts it better than I can:

*"A eutectic system is a mixture of chemical compounds or elements that have a single chemical composition that solidifies at a lower temperature than any other composition made up of the same ingredients."*

So if given a choice 63/37 is a better choice for solder.

LDBennett


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## erkenbrand (Dec 6, 2010)

I also usually use the 60/40 stuff from Radio Shack. Since I also do a lot of work with audio amplifiers, I tend to grab this because it's near to hand on my bench (silver bearing): http://www.welbornelabs.com/cat/solder.htm It's more expensive, but melts and flows beautifully. I've tried using liquid flux, but found it didn't help much except when tinning wires.

It also pays to buy the good soldering iron. Although the cheap ones are tempting, you just don't get very good control, and if you're going to be using it heavily you'll burn them out. I found a used Therm-o-Trac on eBay for $75 (normally ~$500 new). After 10 years it's still going strong, and I have no idea how many hours were already in it before I got it. (But I'm sure many. It's ugly as sin.)


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## clovis (Jan 5, 2014)

Great topic and thread...but, does anyone else keep seeing the title of this thread on the main O forum page, and think it reads:

Soldier recommendation?

I have a relative in the Marine Corp.

LOL.


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## stevetil (Sep 6, 2011)

I do have a few toy soldiers on my layout.
But no, I read solder, because I am an electronical guy.


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## Big Mike (Dec 2, 2011)

Dave Farquhar said:


> The mixture of the alloy makes a difference too. Radio Shack sells a 63/37 solder that has a nice low melting point that makes it easy to work with. You may be able to find that alloy in a hardware store too. Radio Shack also has a solder tip cleaning/tinning solution. It's expensive (about $10) but lasts a long time and makes soldering easier. I think it's worth it for the frustration it saves.


 
the 63/37 or something close to it is what I like to use for small wire up to 20 ga. I use 1/16 dia. solid core , 1/8 for 18 ga. or larger wire.................Mike


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## Robes (Jan 5, 2011)

Found some in an old tool box out in the tool shed.... 95/5. Can anyone explain what the numbers mean.


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## rkenney (Aug 10, 2013)

95% Tin and 5% Antimony. 450°F - 464°F melting range - for plumbing


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## Robes (Jan 5, 2011)

All-righty then... I'll chuck that in the plumbing toolbox.....


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## sjm9911 (Dec 20, 2012)

Allright, nothing about train soldering. But that digging up stuff in an old tool box made me remember a story. I had a broken pipe and some old tools my father left behind. I figured not to hard I can do this. I cut out the broken part, drained the pipe, and hooked up a sleave to join the pipes. I took out the old torch an flux and began to solder. 4 hours later, nothing. I used a whole coil of solder and nothing was sticking. I called a friend who said throw all the old stuff out. As I was putting the cover on the old tin flux container it flipped over. It was actually heat proof grease with a flux top. Dough!


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## Robes (Jan 5, 2011)

Yep,... been there, done that,... and bought the T-shirt!! I took that solder and put it in a zip bag along with a piece of paper and notated the info that Bob gave me above before I put it in the plumbing tool box. I bought the T-shirt once..... not gonna buy it again!


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## gunrunnerjohn (Nov 10, 2010)

I've twice come to the rescue of folks trying to sweat a pipe joint. Both times they had used a whole roll of solder and still couldn't stop the leaks! Both times they were amazed that I was able to solder it on the first try in a couple of minutes. 

The one guy was my neighbor that had borrowed my propane torch. When he came back and asked if I had a new gas cylinder, I decided that it would be cheaper to go see what the issue was. He had the neatest little mountain of solder under the pipe on the concrete floor, amazing stuff! 

Soldering is actually very simple if you use the right technique, and seems impossible if you don't follow the rules.


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## Lynn D Bennett (Jul 27, 2013)

The surfaces to be soldered MUST BE CLEAN. Flux alone is not enough sometimes. For copper plumbing you have to sand the pipe and the inside of the fitting to remove all the corrosion before attempting to solder the pipes. That can go for soldering wiring to tracks as well.

There are a couple of ways to solder a joint that work. If you use the soldering iron to heat the joint and let the hot joint melt the solder and not the iron that works well. Another way is to tin the parts and just heat the two placed together with the iron. Don't move the joint until the solder has solidified.

If the soldered joint is not shiny after it cools then it is a "cold" solder joint that conducts poorly and is not very strong.

LDBennett


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## Robes (Jan 5, 2011)

_If the soldered joint is not shiny after it cools then it is a "cold" solder joint that conducts poorly and is not very strong._

There is my one thing learned for today! I went into town for a grain run and as I was driving along I glanced in the rear-view mirror and did a double take. I spotted a Radio Shack a mile away from the grain store. On the way back I stopped in and the guy said he has been there for 20 yrs! I NEVER noticed it before. I was going to head about 10 miles down the road to a NEW Radio Shack that opened about a year ago. Got my solder,... picked up some wire and was eyeballing a soldering station....
Speaking of that.... Weller is a good name,... anyone want to add to the list of good soldering stations?


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## raleets (Jan 2, 2011)

Robes,
100% agree. I've used a Weller soldering gun forever. Mine must be at least 35 years old but still looks and works great.
One of my favorite little things to do is "flick" the hot solder off the tip of the gun onto my cold concrete floor in the garage. I'll do this several times during a soldering session, then pick up all the little dabs of solder and roll them into a ball or other shape. You can use them in junk piles, etc., on your layout.
Bob
P.S. You're also 100% correct about the solder joint being bright and shiny. If it's not, then it's NOT soldered correctly and will fail you every time.


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## rzw0wr (Aug 28, 2013)

Radio Shack irons are OK.
The tips burn up fairly quickly.
I have a 20w/40w station that is working well.
You can not but conical tip for this though.
I buy the chisel tip and make my own.

Weller is a lot better iron.


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## Robes (Jan 5, 2011)

Wow.... what a difference. Picked up the correct solder.... and between that and learning "tinning".... sure makes the process a boat-load easier. I also find that making use of that piece of tooling with the alligator clips (mine has a magnifier attached to it too) comes in handy to hold things whilst soldering. Learning to recognize a cold solder joint gives you confidence you did it right. Before it was an "I wonder if the solder connection is good" nagging question...


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## rkenney (Aug 10, 2013)

Three things that help when soldering with 'small' irons:

1. Use a stand for the iron that holds the tip away from objects when not in use but heated (keeps tip hot by eliminating contact).

2. Use a wet sponge to clean the tip occasionally (prevents crud buildup).

3. when heating the joint (especially for sensitive electronics) a small amount of solder flowed into the joint actually carries the heat into the connection. Prolonged heating with the tip alone can destroy the component. Continue heating only long enough to evaporate the flux.


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## Robes (Jan 5, 2011)

#1,.... check! My house is 160 yrs old so I am damn careful about ANYTHING hot.
#2 & #3,.... good to know!!!!!!!!


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## TrainLarry (Jan 15, 2012)

Adding to Bob's suggestion #3, when soldering any electronic component (especially semiconductors, ie. diodes, transistors, integrated circuits), it is a good idea to clip a heatsink as close to the body of the component as possible to dissapate any heat. A small alligator clip does well.

Larry


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## Dave Sams (Nov 24, 2010)

BigAl56 said:


> For soldering wires to track I use solid core solder with flux found in the plumbing section.


BTW BIG AL

If you switch to rosin flux (like we are supposed to use), you will be amazed how long the tips will last on your iron!

I used acid flux for years and made the switch after some advice from this forum.

You will also find the proper solder melts much faster and flows better than the plumbing solder.


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## Lynn D Bennett (Jul 27, 2013)

Today plumbing solder is absolutely not the solder to use on electronic components. It is mostly tin and is that way to accommodate the EPA as the lead in the solder joint of years past supposedly was a health hazard. Solder used in mechanical systems like plumbing is acid core which destroys electronic components and should not be used for electronics. 

Rosin core solder is the one to use with the makeup of 60/40 or 63/37 lead to tin. That combo of lead to tin lowers the melting point of the alloy to the lowest it can ever get. You can buy small bottles of liquid rosin from Radio Shack and add that to the joint too. The electronic assemblers where I worked who built military equipment used both on every joint. But rosin will only do so much to clean the joint. The metals must be clean to start with and rosin only removes the light oxidation found on bare copper after it has been cleaned.

LDBennett


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## OldMarxGuy (Jan 22, 2014)

Cleanliness is important in soldering, old oily/dirty track pins and sockets don't solder well unless you pull and clean the pins and clean the sockets, recrimp sockets and flow solder into sockets using rosin core solder and extra rosin paste flux with 75 or more watt iron and good soldering technique. The idea is to heat the track and pins to solder flow temperature as quickly possible and remove heat before you damage plastic parts if any.


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