Can't Solder?

So often I run into people who "can't solder".

My sister can solder. In fact, she's a rework operator at a big electronics plant which shall go nameless and she teaches the new hire class for assemblers. Her pass rate is well over 99% and except for techs and engineers going through, all her pupils are women who have never soldered before. Guys, if a bunch of GIRLS can do it, why can't YOU?

Proper soldering is not that tough. I learned to do it out of books, and later went through a solder school or two while working in electronic plants while in college. The only thing that ever gave me trouble was the smaller surface mount stuff. Yet, so many people in audio and ham radio have a huge problem making acceptable solder joints and others refuse to try. I refuse to believe anyone who can play any musical instrument at all-except maybe a trombone- can not learn to solder correctly and in a short time.

The biggest mistake people make is not understanding what is required to make good solder joints. You need a soldering iron with a clean, tinned tip, a clean pair of metal items-wires, leads, tags, pads, whatever-and some solder and flux.

For chassis and panel soldering, a regular electric iron-NOT a gun, an iron-will work, but if you want to solder circuit boards, it HAS to be a temperature controlled iron. You HAVE to be able to CLEAN and TIN the tip, EACH USE. You need to have the surfaces clean, so you will want a small ACID BRUSH and some SOLVENT, usually mineral spirits or methanol.

Tinning the tip means you need a SPONGE with some WATER on it. You can use real natural sponge or the kind sold just for soldering, (but not the cheap kitchen type) and DI or distilled water is better but not mandatory. You also need some SOLDER.

The ONLY kind of solder to use until you are highly experienced is FRESH, ROSIN CORE solder of 63/37 lead-tin composition. It has a special name, EUTECTIC solder. That is because it goes from liquid to solid in one instant as it cools instead of going through a mushy stage. It has to be ROSIN CORE, you must NEVER use acid core solder on electronic items. It is for plumbing and sheet metal work.

You will also want some FLUX. The kind you want is called RMA Flux. That stands for Rosin Mildly Activated. You must carefully clean each joint you make after using it. You will also want a little solvent for the flux and a small needle bottle for dispensing it. You should use little flux. There is also a paste flux you can get that is non-acidic that is good mostly for tinning old or chewed up soldering iron tips. Rarely you might use a little on a particularly big solder joint. Flux goes bad which is why you want to start with a fresh roll of solder.

You will also want some tools such as a couple of picks, needlenose pliers and other miscellany.

If you have acid core or fluxless tin/lead solder, unless you do tinsmithing or plumbing, get rid of it. If you have a soldering gun, put it aside for other purposes or get rid of it. If you have old cheap unregulated irons, they can be used for chassis and panel (point to point) soldering if you can get the tips cleaned and tinned, otherwise get rid of them.

If you buy everything you need at one time from a good supplier like Stanley Supply and Services, (the former Jensen Tool people) you

are going to lay out a couple hundred bucks. If you do some hamfest trading you can get everything but the solder, sponge, holder, and flux for less.

Chassis and panel soldering is well described in the old military electronics books. The thing to do is get some wire and supplies and practice. Practice a lot.

I have been through a couple of company solder schools, but the best I have been through was as a guest with the old GTE Telephone craft class for inplant repairers in the early eighties. One of the exercises we did was to take a piece of wire-regular solid copper wire, perhaps 12 or 14 gauge, and cut it into twelve exactly equal pieces. We then had to build a square of four pieces and then a cube using all twelve. The only tools we were allowed were the soldering iron, solder, a pair of phone man needlenose pliers and a pair of surgical forceps like needle clamps or hemostats. We also had a steel plate about 3x5 inches which had a surface that looked as if it had been rusted and then oiled and buffed.

When we were done with our perfect cubes-which took half the day-they crushed them. The solder joints had to hold.

The first cube took hours. By the end of the day most of us were on our fourth or fifth. The instructors then showed us how they did it-they could do it in five minutes flat, starting with the untrimmed, unstripped wire.

Today, phone companies do very little soldering-it's all punchdown blocks. But in the old days, they got really good at it.