Tuesday, February 19, 2013

Soldering Irons

One of my readers asked the question recently:
What do you use for soldering?
That was a topic that I hadn't thought of writing about. Today, I fix that.

Soldering is a vital skill for playing with electronics. Breadboards and twisting wires together are useful for prototyping, but they will only get you so far. They leave much to be desired when you want something reliable and durable.

Soldering is one of the best ways to make electrical connections. It is easy to learn, and all it takes is a good bit of practice to become proficient.

But, I have to admit that decent tools make it much, much easier to learn.

Like many, I started off soldering with a very cheap soldering iron. It was old, underpowered, and not temperature-controlled. But, it was free.

There are several problems with cheap soldering irons. If it is a low-wattage model, it will take a while to get up to temperature. Trying to solder with an iron that is too cool can actually increase the likelihood of damaging some of the more delicate and temperature sensitive electronic components. The iron is too cool to melt the solder effectively, but it is hot enough to cause harm. This is usually made worse since you will be holding it against the part you are trying (and failing) to solder for a much longer time than usual.

If it is overpowered, or if even a lower-wattage one is left on for too long without using it, it will get too hot. This will make it more likely to damage things as well. Using an iron that is too hot has caused me to lift the traces off of a circuit board more times than I would like to admit.

That is what I started with. I currently own three different soldering irons:

My workhorse is a Weller W60P purchased from Altex for about $70. (As a side note, Altex is one of my favorite stores. It is one of the few remaining electronics stores that still sells soldering tools and equipment. However, they no longer carry this model.)

The W60P is 60 watts, so it has plenty of power and heats up in about a minute. It has a temperature-controlled tip, so it never gets too hot. I have never damaged a circuit board using this iron. It is a joy to use.

The only problem with the W60P is that the temperature-controlled tip doesn't get hot enough for some of the higher temperature solders used in some electronics. It is not adjustable without replacing the tip. This is why I have a cheap backup for when I need something hotter.

My high-temperature backup is a Craftsman model 113.540420. This cost about $12. It is 45 watts and without temperature control. It gets more than hot enough to work with high temperature solders.

I have the third soldering iron for portability. Sometimes it is terribly inconvenient to be tied to an electrical outlet. For those situations I have a butane-powered BernzOmatic Soldering Torch purchased from Lowes. It cost about $20. It can get very, very hot. It is suited more for soldering wires than for delicate work. It is incredibly convenient to have around. I use it mostly for working on my car, since I don't have the luxury of a garage or outdoor outlets at my apartment. The hot knife tip is also useful for cutting nylon rope.

Since it doesn't have a built in igniter, I keep a butane lighter stored with it.

That is my fleet of soldering irons. Note that the cord to the W60P is not in the best shape. It turns out that using something that gets over 700F near a cord that melts around 320F can be problematic at times.

This is why it is important to have a proper stand. In addition to avoiding melted cords, the stand also prevents the soldering iron from rolling off the table. Since things like laps, legs, and feet are typically below the edge of a table, and soldiering irons are incredibly hot, the importance of a stand cannot be overstated.

Don't forget to dampen the sponge for periodically cleaning the oxidized solder from the tip of the hot iron.

This is another useful and inexpensive tool to have around. Everyone needs a helping hand every once in a while. It takes one hand to hold the soldering iron and a second to hold and apply the solder. That doesn't leave many hands to hold the work. Most of the time it is ok setting the work on a table. However, sometimes things need to be positioned or held more precisely.

There is one other thing that is required for making a good solder joint:  good solder. I prefer small diameter solder 0.025" or so. It should be rosin core for electrical work. Never use acid core solder. Acid core solder is only for plumbing or structural applications.

60/40 lead/tin solder is good. 63/37 lead/tin solder is better. The 63% lead and 37% tin alloy is the eutectic mixture of these metals. This means that there is a single melting point instead of a melting point range. For any other proportion of lead and tin, one of the two metals starts solidifying first and then the other. If the work is disturbed while the solder is partially solidified, you get a poor connection. Using the eutectic alloy reduces the chances of this happening.

Also, this is a good time to note that you are playing with lead. It is not the friendliest heavy metal out there. Always work outdoors or with proper ventilation. Wash your hands. Eat elsewhere.

When soldering, you will often have the need to de-solder something. My favorite tool for this is solder wick. This is a fine braided copper wire saturated with rosin flux. If this is placed over a solder joint and then heated with an iron, it wicks up the solder and removes it from the joint. This is surprisingly clean and easy to do.

 The other option for removing solder from a circuit board is a solder sucker. It is a spring loaded plunger with a Teflon tip that can withstand high temperatures. You compress the plunger until it clicks in place. Then you melt the solder joint, quickly place the tip of the solder sucker into the molten solder, and press the release button on the side. This releases the plunger and the spring pushes it out causing a rapid vacuum action. This sucks the solder right out of the joint... in theory. I haven't had the best luck with this. Sometimes it works for me, sometimes it doesn't. The tip tends to clog with hardened solder and requires occasional cleaning. I tend to prefer the solder wick.

That sums up my arsenal of soldering equipment. Every tool is not necessary, but each has its uses. This is probably a much longer answer than that reader expected from such a simple question, but it turns out that I had quite a bit to say about it.

1 comment:

  1. Hi,
    Tks for ur info. As I'm pretty new to soldering properly myself (been soldering for years, not clean and appropriate lol)
    I have that same old craftsman workhorse iron 113.540420. My orignal tip got broke off. For the life of me can't get rest of it out to install new tip I have for it. I'm read to start drilling it out. Bought cheap auto store 30w and doING bunch of work on wife's caddie. Having all issues u listed with under powered iron. Ready to pull hair out or....