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What Kind of Solder Should We Be Using?

snopercod

Well Known Member
I recently had occasion to partially rewire my G205 Stick Grip due to broken wires (see this thread). When I went to purchase some rosin core solder on Amazon, I discovered that there are several available alloys with several different kinds of flux. I used to be an electronic technician in another life so I was embarrassed that I didn't know about solder any more (if I ever did); I just used what the tool crib gave me - Kester "44", I think it was.

The European Union really screwed us over with their RoHS, which banned lead in many products. I won't go into that disaster, but thankfully we can still buy the tried and true 60/40 and 63/37 solder on Amazon. The 63/37 is "Eutectic" solder and melts at the lowest possible temperature and solidifies without going through a "plastic" phase. This theoretically gives you a better joint, so I jumped the gun and ordered some made-in-china 63/37 before I did the research on fluxes. I have no idea which flux it contains.

Flux cores can be Rosin (RO), Resin (RE), Organic (OR), Inorganic (IN), and RA (Activated Rosin). They are further rated according to the residue activity (L=Low or none; M=Moderate; H=high). So for example, a Rosin Core, Moderate Activity flux would be classified as ROM0 or ROM1, depending on Halide concentration per J-STD-004. There are also different core sizes: 50, 58 and 66 = 1.1%, 2.2% and 3.3% flux. Yeah, I really don't want to know all this stuff either, I just want to know what we should be using on our planes.

In the G205 thread (linked above), I found several 26 GA wires in my stick grip hanging by a thread. When I went to make repairs, several more wires just broke off where the insulation starts. Could this have been due to using a too-agressive flux ten years ago when I wired up the connections? Improper stripping? Or maybe it was just the vibration after five years in service. I'll never know but I was careful to properly restrain these small wires this time around.

I think if I were doing it again, I would use Kester 24-6337-0027, Core Size 66, 63/37 Alloy
Kester 44 Rosin Flux is an activated rosin formula for use in flux-cored solder wire. 44 has virtually dominated the field
of activated rosin core solders for well over five decades. An outstanding performance feature of this flux is the ?instant-
action? wetting behavior. The high mobility and fast-spreading action of this flux results in more reliable production line
soldering. Under IPC J-STD-004, 44 is classified as ROM1. Despite the increased activity and soldering performance, 44
passes both 85?C/85% RH and 40?C/90% RH SIR test methods.
So what are you guys using? What should we be using?
 
Solder

The proper way to use solder in aircraft is to use none.
That is why crimp on terminals are made. I know they are more expensive, however you usually don't find them breaking at the end of the solder joint due to vibration.

Mike Hepperlen
A&P Tech counselor
 
The proper way to use solder in aircraft is to use none.
That is why crimp on terminals are made. I know they are more expensive, however you usually don't find them breaking at the end of the solder joint due to vibration.

Mike Hepperlen
A&P Tech counselor

I've yet to see a crimp connector for a headset jack.
 
60/40

Back to the original OP ?
Use 60/40. Whether you choose resin core or no resin core is up to you; however, you should have some resin available to perform the "cleaning" function that results in a proper electronic connection. Be sure to clean the finished product after the soldering is done so no resin remains in evidence.
 
The Kester 44 was the standard that I know. It is 60/40 rosin core ROM1 to J - Std 004.

It has been used for years without Post cleaning.
 
1. 26 awg is pretty thin.
2. Put shrink tubing over the wire first, slide it away from the solder joint, then solder. Slide the tubing back over the solder to no-solder region, heat and shrink. This will give some mechanical support to keep the flexing to a minimum, just like a good crimp.
 
The proper way to use solder in aircraft is to use none.
That is why crimp on terminals are made. I know they are more expensive, however you usually don't find them breaking at the end of the solder joint due to vibration.

Mike Hepperlen
A&P Tech counselor

I agree, stay away from solder when you can use a crimp instead.

IF an electrical connection MUST be soldered, then 63/37 Rosin Core Solder would be the recommended one to use.

ALWAYS clean the rosin left behind off the solder joint before calling the connection complete.
 
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Yes, But...

Anywhere you have electrons flowing, there will be places that "must be" soldered. There's just no other way of making the "permanent" connection.
Whether you use 60/40 or 63/37 - makes no bloody difference - just clean the resin after the heat dissipates.

Once you have accomplished the soldering, provide as much support to the connection to minimize vibration as possible.

If you are making a connection in a wire run, then it is quite advisable to use crimp on connections. Stein has a few videos showing how to do them.

This appears to be a subject quite similar to the "primer wars." Best thing I can say / recommend is: do it the way you believe is best for you.
 
How to clean the rosin?

Add on question:

What's the most effective way to clean the rosin after soldering?

Mark
 
Add on question:

What's the most effective way to clean the rosin after soldering?

Mark

IPA is typically recommended with a stiff bristle brush. Think "acid brush" with bristles cut back to 1/4" or 7 mm.

Not recommended as it can damage some paint printed on the boards but Lacquer Thinner also will remove rosin.
 
I still have a small stock of very, very old Kester lead-tin solder; it's probably 44 but the label is long since worn off the bits of spool that remain. I also have probably a pound and a half of lead-free RoHS compliant solder. It works just fine, and I use it most of the time. Yes, it takes a little higher temperature which is not a problem with the fairly low end Weller WES50 soldering station I use. I didn't like the lead-free solder when I started using it, but I was assembling boards that were going to Germany so I decided to just switch. After some practice it wasn't an issue.

There are certain occasions where it's just not possible, or very inconvenient, to get enough heat and stability to use the lead-free solder, but the tin/lead stuff will do the job. The rest of the time I use the lead-free, because I have more of it and I have it in a much smaller diameter for very fine work. I think my smallest lead-free solder is .020, and the largest is almost suitable for plumbing.
 
When I was an instrument tech in a nuke plant, we used the good stuff: Ethyl Alcohol.

Denatured alcohol is ethyl alcohol with about 5% (?) methyl alcohol added that makes it unsuitable for the cocktail hour.

No reason why a half pint of 195 proof pure grain wouldn?t work just as well, but there?s also no reason to pay additional taxes on potable spirits. :D
 
What's the most effective way to clean the rosin after soldering?

I use alcohol and an old toothbrush ... you suppose to replace that tooth brush every 6 months so you'll always have a supply (just run it through the dish washer first). :D
 
The proper way to use solder in aircraft is to use none.
That is why crimp on terminals are made. I know they are more expensive, however you usually don't find them breaking at the end of the solder joint due to vibration.

Mike Hepperlen
A&P Tech counselor

I've yet to see a crimp connector for a headset jack.
And now you know why the most common communication equipment failure is a broken wire at the headset jack.

When you solder a stranded wire, the soldered portion becomes solid while the rest of the wire remains stranded. That solid/stranded location is the weak point since the strands flex while the solder doesn't. That makes it very susceptible to vibration failure, something a stranded wire alone is not. The more vibrations that location is subject to, the sooner it will fail. This is especially critical if you solder two stranded wires together instead of crimping them.

If you must use solder, then you must provide that solid/stranded point some kind of mechanical support. For small wires the most common support is a piece of heat shrink that extends well into the stranded wire portion. All "professionally" soldered headset jacks will have heat shrink on the wires. An optional method is to use some kind of "clamp" on the wire, again extending into the stranded wire portion which is not an easy task to do. FWIW in the few places I had to solder wires together I used "Solder Sleeve" to provide the mechanical support beyond the stranded portions of the wires. 12 years later and I haven't had a broken wire, yet.

:cool:
 
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Hopefully not too much thread drift here, and posting for my own education:


Does it make sense to make "leads" where a solder connection is necessary? In other words, where you must have a soldered connection, make it to a short, well supported lead wire which in turn is connected using a crimped connection (dsub etc)

My guess is the answer is "NO" (now we have two connections instead of one) but consider this: Pre-wiring a headset jack on the bench with well-supported leads that connect to a dsub or similar connector may give better/more consistent results than crawling into the airplane to solder leads in place. Flame suit on.
 
Does it make sense to make "leads" where a solder connection is necessary?
I think that makes a lot of sense and the same applies for crimped connections. Yesterday I tried to make a crimped connection in a very difficult place: It was dark, access was limited, and I really couldn't see very well. The crimp came out bad and I had to re-do it. The second time I just soldered the two wires together and put heat shrink over them. I could get the soldering iron down in there but not the crimp tool. It was down in here:

t0NIc4.jpg
 
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Hopefully not too much thread drift here, and posting for my own education:


Does it make sense to make "leads" where a solder connection is necessary? In other words, where you must have a soldered connection, make it to a short, well supported lead wire which in turn is connected using a crimped connection (dsub etc)

My guess is the answer is "NO" (now we have two connections instead of one) but consider this: Pre-wiring a headset jack on the bench with well-supported leads that connect to a dsub or similar connector may give better/more consistent results than crawling into the airplane to solder leads in place. Flame suit on.
If you mean to solder the wire, put heat shrink over it then connect to a crimped Dsub via a short pigtail, that is how I did my headset jacks. I accepted the tiny increase of posible failure for ease of future maintenance.

:cool:
 
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If you mean to solder the wire, put heat shrink over it then connect to a crimped Dsub via a short pigtail, that is how I did my headset jacks. I accepted the tiny increase of posible failure for ease of future maintenance.

:cool:

Exactly what I was thinking - thanks Galin!
 
Another reason to solder is that butt splices for 26 AWG are hard to find. Aircraft Spruce has them 26-20 AWG TIN PLATED HEAT-SHRINK BUTT SPLICES but you really need a high-dollar crimping tool to properly crimp them. I had neither on hand in my hangar. In speaking with Ray Allen yesterday, they now offer a G405 stick grip which is pre-wired so the user doesn't have to solder those tiny wires.
 
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