No too long ago, we talked about a great type of solder to use when you want a joint to form smoothly, without too much or too little flux. But today we’re going to talk about what to do when you need to get rid of a soldering joint. Depending on exactly what type of project you’re working on, you may need to disconnect a soldered-on cable connector, or maybe remove a solder bridge from a circuit board. Melting the joint back down is usually enough to break the connection, but how do you remove that little bead of molten solder that’s left over?
Some people like to use a solder suction device, which literally sucks up the solder as soon as you’ve melted a joint. But other people prefer a gentler approach, which involves gradually wicking solder away as it melts with a product known as desoldering braid. Desoldering braid is really pretty simple: it’s woven out of very fine copper strands, which, when held against a melting solder joint, “soak up” (or wick away) the liquified solder, to the point that the braid actually becomes so saturated that it loses its signature copper color, and picks up the color of the solder, instead.
MG Chemicals makes a nice desolderer known as Fine Braid Super Wick, which works as well with jewelry and plumbing as it does with circuit board work. Using Fine Braid Super Wick is easy – just match the diameter of the joint to be removed with braid that’s the same width (or a little bit wider than) it. From there, you fire up your soldering iron, lay the braid across the joint to be removed, and apply your soldering iron directly to the braid. This heats up the copper, which in turn transfers that heat to the solder, causes it to melt, and finally soak into the braid. When you lift away the braid, all of that old solder comes right along with it.
Back when I was just a little kid, way before blogs were invented, my Dad ran a side business installing sound systems in churches. I remember hanging around and watching him solder custom audio cables at home some evenings, and for some reason, I was always dying to get in on the soldering action. It just looked fun. But far be it from any responsible parent to allow their 8 year old daughter to wield a soldering iron, so I was out of luck.
My Dad eventually wound down the custom audio work, and as a result, I pretty much forgot about soldering as less lethal-for-kids projects like friendship bracelets, crepe paper flowers and paint-your-own ceramics came my way. Fast forward to 8th grade, that magical year when public school kids get to experience the wonders of Home Ec, Sewing, Drafting and Wood/Metal Shop, all in two whirlwind semesters. When the “make-a-wire-guy-and-permanently-weld-his-feet-to-a-piece-of-sheet-metal-so-he-looks-like-he’s-walking” portion of the program rolled around, the almighty soldering iron came crashing back into my life, but this time, I was the one holding it.
It’s been around 17 years, and despite the fact that I enjoyed my brief stint as an underage solderer, what I remember most is the flux. The gunky, nasty, greasy tins of flux that we had to dunk our solder into. Without fail, we’d always use too much or too little, and would either end up with a joint that wouldn’t take, or a mess of excess flux spitting and running everywhere. But believe it or not, flux issues can get even worse.
While the excess flux issue was annoying for Junior High-aged me, I imagine that it’s even more frustrating for people who, say, make a living soldering printed circuit boards. While soldering is a vital part of electronics in general, residual flux on circuit boards can cause shorts and electrical leakage, or interfere with a board’s thermal properties. And if you’re not careful while trying to remove flux residue, even more damage can occur.
That’s why MG Chemicals’ lead-free flux-core solder is so great. Filled with a core of just the right amount of flux, this solder leaves behind a bare minimum of residue, so there’s little or no cleanup involved. Whatever flux residue does remain is hard and nonconductive, so it doesn’t carry the threats of diverting electricity or causing shorts. As a bonus, the silver-infused lead-free formula saves you from inhaling potentially harmful lead vapors, but also leaves you with solder joints that have excellent conductivity.