Best solder for electrical connections??

[Bob Kontak]

I was rigging up a 12V test light using an old 911 bulb from my "extra" box and there was a plop of solder (lead?) on the contact tip of the bulb that melted like butter and was super simple to melt the wire into it.

I am no electrician and know that I have soldered many a wire using plumbing solder. Often with the finished product looking like my first attempts to stick weld in junior high school shop class.

What is the solder I should use? Flux/rosin, lead content? Soldering gun or tip for general wiring with the occasional venture onto a circuit board?

I can probably find the info on a website but want to ask this community because of the variety of DIY electrical "repairs" you guys perform. Is there a one kit answer?

Here is my kit for those in the know to have a chuckle:

[Bob Kontak]

Oops - Here is the pic I meant to post above.

[Tippy]

I'm far from an expert but I would think you should avoid a soldering gun around a circuit board or small wires since it puts out so much heat which would can burn up a component or melt the insulation quickly. I believe those are considered medium range.

I bought a cheap Wellerman soldering iron for like $10-15 and did my entire MegaSquirt install with it. It didn't have enough heat to solder an 8 gauge wire together, but for the 20-22 AWG wires, it worked perfect.

Plumbing uses acid core which should be avoided for electronics, rather use a rosin flux. I was recommended 60% tin, 40% lead solder for the work I was doing. Can't remember diameter but it is (IIRC) high 0.020" to low 0.030" size for small wiring.

[T77911S]

hey bob, im an electronics tech, i never use those big soldering guns, not unless you plan to do something with maybe 8 gauge wire or something likt that. i use just a regular soldering iron and 1.0mm solder, solid core. if i need flux, i can just dip the tip of the wire into some flux paste. i dont always use flux, only if the solder does not want to flow.
keep it clean. apply the heat and let the solder flow to the heat. soemtimes a drop of solder on the tip of the iron helps transfer heat to what you are soldering, or de-soldering.

[Chuck.H]

+1 on the solder flux paste, I use the stuff in the little round tin from Radio Shack, it works awesome for me. I just dip the tip on it before soldering and it makes solder flow WAY better.

Lately though I've been using crimped connectors rather than soldering - I use the welded 'uninsulated' crimps and a good crimping tool. I believe this makes a more secure connection that withstands vibration better than soldering, but I understand this is very subjective so there will be lots of opinions for/against soldering/crimping.

Chuck.H
'89 TurboLookTarga, 334k miles

[Jdub]

Flux can turn around and corrode a join. This is one reason why I do not use the "in situ" core flux type solder line. Instead, apply to tip from a separate tin. Also, be sure to apply lukewarm water and a worn toothbrush to remove flux from your work.

[RWebb]

any irons, tips, heat sinks, etc. that have touched acid core solder must NOT be use on any electrical connections

[SoCalSK8r]

OK,
I do this for a living (evaluate suppliers making cable assemblies).

I wouldn't use anything in the pictures above:
-as stated, if soldering iron was used for plumbing type of solder, don't use it on electronics
-I would stay away from lead free solder - people required to use lead free solder wish they didn't have to use it. It's harder to work with, requires much higher temperatures, leads to a more brittle joint, and has other characteristics which make it not a good choice

So, go to the local radio shack and pick up a new soldering iron (cheapy is fine), some leaded solder with rosin core, and you are golden.

Do not use additional flux. it can cause a lot of other issues and quite frankly isn't required unless you have some really dirty joints you are trying to bond. Even then, without proper temperatures to activate all the components in the flux, or without a good cleaning, you will leave behind chemistry that can cause corrosion.

For soldering, make sure you heat up the components you wish to solder, then bring your solder wire over to the hot component and feed it the solder. NEVER touch the solder directly to the soldering iron as this will inherently give you a cold solder joint which will fail over time.

With leaded solder, you should have a nice, shiny, smooth solder joint when finished. If it is dull, you have a cold joint.

Lastly, don't over do it with the solder. Too much solder is just as problematic as too little. You really only want enough to cover the surface and make a nice clean fillet to the mating part. A big old blob of solder is not helpful...actually it's bad.

[jrumiano]

Whatever you do toss that plumbers soldering paste! The acid in it will destroy traces on circuit boards and corrode wiring. I learned that lesson when I was about 7 or 8 years old building an electronic kit. If you use good quality flux core solder (Kester) that's all you need. Use a wet paper towel to keep the tip clean on you soldering device clean. Clean it every time you solder a joint. If you're soldering wiring a gun in the low setting (first click on the trigger) can work but you need to work fast and not overheat the joint and melt the insulation. If you're doing circuit board work a 25 or 30 watt iron is what you want.

Good luck.

John

[steely]

Originally Posted by Jdub

Also, be sure to apply lukewarm water and a worn toothbrush to remove flux from your work.

I use alcohol instead (and not a lot) and a small throw-away brush - cotton swab may be ok to dab, but strands stick to some work.

+1 on everything else. That Silver solder is for plumbing I think. I hate it even for that.

I use a pen soldering iron and replace the tips. As said before CLEANING and heating are your friends. I bought the cheapy pen iron with the cheapy stand that has a spring to hold the iron in between use.

[timmy2]

This is my setup for home hobbies like repairing iphones.
Hot air station works well, can't afford IR for hobbies....
I used the hot air unit to re-attach the post on my hood emblem, worked great!
There is a variable temp soldering iron on the right as well.
For Solder, Kester "44" rosin core .75 mm 60/40 is what I use.

[manbridge 74]

Search Hemmings online as I believe those guys swear on 5 core rosin solder for electronics. I have used it and it is excellent.

A small tip is best or clean your large tip gun very well with aluminum oxide paper etc, using a 25-50 foot extension cord to limit amps.

[Bob Kontak]

Thanks all.

Glad I asked. Did not anticipate much response but this is outstanding.

Need to get to the electronics store buy some new gear and practice some heat application since I am used to using the monstro-gun with the wrong flux and the wrong solder. But other than those small issues, I was spot on. :-) Oh, and the not cleaning the tip thing. I did know the solder had to be sucked into the work, at least.

[ant7]

Good old 60/40 lead and tin,
Much more reliable than that crappy lead free stuff we have to use now for new construction, but us techy's can still use leaded solder for re-work [thank goodness] apparently the millitary still use leaded soldered equipment, and so do the medical industry, so what does that tell us.
Hope you got it sorted.
Anthony.

[Tippy]

Originally Posted by timmy2

Wow!

[Bob Kontak]

Originally Posted by Tippy

Wow!

Very impressive, indeed. I thought it was a drill chuck at first then saw the zoomed back picture.

I am on my way to to the hardware store. Thanks again, guys.

[T77911S]

i am like socal, i dont use flux unless it is needed. it is corrosive. use denatured alcohol for clean up.

[jetstar911]

I build and mod hi-end home and car tube amplifiers. I use a silver based solder for everything i do. I also built my harness for my car with the type of solder. Haven't any problems so far.

[ant7]

Originally Posted by jetstar911

I build and mod hi-end home and car tube amplifiers. I use a silver based solder for everything i do. I also built my harness for my car with the type of solder. Haven't any problems so far.

We may have a lot in common, i also repair/modify, and build bespoke valve audio equipment.
I also use a silver loaded solder for new builds and modifications etc.
Anthony.