Soldering Tutorial for the Thermally Disinclined

As promised/threatened in TD2253's excellent motorized rangefinder thread, I've started putting together a tutorial on soldering for those folks who find themselves .

This will be an ongoing project as I find time to sit, write, and find or take good example photos. The only thing I have finished right this moment is the "Safety" portion, but since there's always time for safety (right? RIGHT?) I'll go ahead and post that while I continue work on some tool information.

Feel free to jump right in and ask questions if you want - even if it's something I'm going to cover in a tutorial installment, I'll gladly answer anything I can. Along with that, I do not consider myself infallible or all-knowing by any stretch, so if anyone else wants to chime in and answer questions I welcome and encourage you to do so.
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Soldering 101, or "So, you'd like to burn your fingerprints off!"

Many people view soldering as a mysterious art, practiced and mastered only by pasty basement-dwelling nerds surrounded by hundreds of pounds of electronic equipment and empty Mountain Dew bottles. While true to a certain extent, these conditions are certainly not a prerequisite to becoming an accomplished solderer. Er. Solderererr. Whatever.

Rumor has it that many species of monkeys have, in fact, been taught to solder with proper instruction and ample practice time. You're not going to let a trained monkey make you look like an untrained monkey, are you? Of course you're not, so let's get started!


Next post: Safety

SAFETY

Please, please read this section. Please.

I'd like to take some time to review the safety hazards associated with soldering. This section will be devoid of humor because safety is a generally humorless subject, much like Statistics.

You're going to be working with extremely hot tools, a dangerous chemical or two, and of course, lead-based solder. There are some key precautions to take when working around and with any of these things:

* First and foremost - and this should really go without saying, but I'm going to say it quickly anyway - Keep your children away from your soldering area. Enough said.

* WEAR SAFETY GLASSES WHEN SOLDERING. If you don't have a pair of decent safety glasses (which you should have anyway for working with many tools) you need to stop reading right now and go pick up a set. Go ahead, I'll wait.

Any hardware store, welding shop, or home improvement store will carry several types of eye protection. If the pair you buy isn't comfortable or does not fit well, return them and get a different one. I cannot stress the importance of eye protection enough. Hot solder and flux can/will splatter, and an inadvertent bump to your soldering iron can cause blobs of hot solder to fly off the tip. Your eyes are far, far too important to not make the $10-20 investment in glasses.

* Be aware at all times of your proximity to the soldering iron, and its proximity to everything else. When you're not actually holding it, it needs to be properly stored on its stand or in its holder, away from any combustible materials. The business end of the iron can easily be in excess of 800 degrees Fahrenheit (427C) and will cause a very serious burn before you even feel it happen. It can also potentially ignite paper or cloth if left in contact for more than a few seconds.

* Solder contains lead, which is a known health hazard. For a fairly concise breakdown of what exposure means to you, I invite you to read the U.S. Department of Labor's information on the health effects:
http://www.osha.gov/SLTC/lead/recognition.html
While it is certainly a hazardous material, it can be worked with safely. Wash your hands very thoroughly after doing any soldering. Do not eat, drink, or smoke while soldering or before you've washed up. Be sure you have educated yourself on the hazards and take every step possible to mitigate them.

* Ventilation is also important - soldering will produce lead fumes. It is extremely important to have a well-ventilated area in which to perform your work. Crack a window, set up a fan to circulate air throughout the room, or even (in all seriousness) solder in your bathroom under the exhaust fan - whatever you can do to keep the air as fresh as possible. This will go a long way toward minimizing inhalation of the fumes.

* You may be using solder flux and isopropyl alcohol, both of which have their own unique hazards. Read the packaging carefully and take the manufacturer's recommended precautions before using these or any other chemicals.

* Keep your hobby/utility knives capped or retracted when not in use. Store them in an area of your workspace where they will not roll away or be knocked around. A good, heavy ceramic coffee cup is a great place for sharp tools.

SAFETY IS YOUR RESPONSIBILITY. Please take it seriously.

Next post: Tools

Tools

As with most projects, your tools are just as important as your technique. Investing in quality soldering tools will make your work easier, neater, safer, and more enjoyable.

Soldering Irons

This is pretty obviously the most important tool you'll need. Irons come in varying shapes, sizes, wattages, and levels of quality. Here are a couple examples:


30-watt pencil iron


40-watt station with adjustable temperature control

At a minimum, I recommend a 30-watt pencil iron. Lower wattages will mean less heat, and less heat makes the job harder. A 40-watt unit will run about as hot as a 30W, but will be able to maintain that heat level better while in contact with the work. Either is a fine choice for virtually all home and hobby soldering, but if you can spring for a 40W or greater soldering station (temp control optional, but can be handy) then I recommend doing so.

Don't go overboard!

This picture shows a soldering gun, which typically starts at about 100 watts and is waaaaay overkill for doing small work. I own a soldering gun, and I don't believe I've ever actually used it.

All three units shown above are made by Weller. They produce good, quality soldering tools and to the best of my knowledge they are available worldwide. They have a huge selection of models in varying price ranges.

I do not like Radio Shack's soldering irons. They are very underwhelming. They do, however, sell Weller products on their web site. Spend a little more and buy something good - you'll thank yourself later.


Note that I have not yet mentioned the "Cold Heat" soldering iron. Well, except for just now. But this is the only time you'll see me type those two words without a preceding..."colorful metaphor." They have very limited applications and are NOT suitable for use on electronics, no matter what the commercial might tell you. Just forget I even mentioned it at all and we'll all be happier.

Wire strippers

There are roughly 4.7 quadrillion different styles of wire strippers, and everyone seems to like something different. I personally prefer the Stripmaster tools such as this one:


Lay the wire in, squeeze the handles together, and the job is done. If you don't want to spend the money on these, a $5 tool from the auto or hardware store will probably do you just fine.

Multimeter


Analog


Digital

It's always nice to be able to check voltages and circuit continuity. I do like Radio Shack's selection, and both units pictured above are under US$20. Just don't count on the sales person to know much about them.

Other Tools

You'll want things like hobby/utility knives, various screwdrivers, maybe a small vise or "helping hands," a magnifying glass, small pliers, wire cutters...the list is potentially endless. My rule of thumb: if you find that you need it, and you don't have it, you'd better go buy it.

My wife hates that rule.

Next post: Solder and Materials

Solder and Materials

Solder comes in a lot of different alloys, different sizes, and may or may not have a hollow core filled with something called rosin. Rosin is a type of flux, and flux is basically a substance that promotes heat transfer and solder flow. You should never, never, never work without either a rosin core solder or an externally applied flux. You'll only be hurting the project you love. I prefer using solid solder and applying a separate flux product, but that's just the way I was taught. There's nothing wrong with doing it either way.

For simplicity, I'm only going to talk about two solder types. Both are standard lead/tin alloys and differ only in their ratio.

By far, the most common solder you'll find is a 60%/40% tin/lead alloy. It's widely available and comes in both solid and rosin core varieties. It melts at about 370F (188C), flows readily, and is a good conductor of electricity.

The stuff *I* prefer (you're going to see a lot of my preferences during the course of this, I guess ) is a 63/37 alloy known as eutectic (yoo-TEK-tik) solder. It melts specifically at 361F (182.7C) and has no plastic, or pasty, phase. It goes directly from a solid to a liquid, and from liquid back to solid. The advantage to this will become apparent later on when we actually talk about making a proper solder joint.

The physical size of the solder you use is really dependent on what you're comfortable working with. It comes in many different diameters. I keep a roll of small stuff and a roll of big stuff...these terms will mean different things to different people. I use the smaller stuff for soldering, and the bigger stuff exclusively for "tip maintenance" on my soldering iron. Again, I'll touch on this later.

Flux

As stated before, applying flux to a solder joint will promote heat transfer and aid in solder flow. Caveat Fluxor: some flux products are actually corrosive and can damage circuits over time if not cleaned properly. If you recall reading a quick note about Isopropyl Alcohol in the Safety lecture, this is where that will come in. Alcohol and a small, stiff brush (look for "acid brushes" at the hardware store) will make quick work of the flux residue after your joint has cooled. This whole scenario is easy to avoid, though - non-corrosive fluxes are the rule rather than the exception these days. It's very easy to purchase an appropriate product, be it paste or liquid flux. The choice, again, is up to you. (I prefer paste.)

Solder Wick



Solder wick, or desoldering braid, s a length of braided copper that actually removes solder from a connection when applied and heated. Very handy stuff!

For a really good selection of solder and flux products in the US, I recommend these folks: http://www.action-electronics.com/kester.htm Fair prices, fast delivery (in my experience) and enough variety to fit almost any application.

I think that about covers it. I'm done writing for the night, but tune back in tomorrow when we start the real meat 'n' potatoes portion of the tutorial!

Next post: Making Your First (Good) Solder Connection

Sorry for the delay on the next installment...been real busy the last couple of days. I'm working on it when I can and should have something up in the next day or two.

Excellent soldering tips Rick! Thanks!8) :cheers