Edge / IoT / Tools

Off-The-Shelf Hacker: The Art of Soldering

4 May 2019 6:00am, by

Quite a while back I covered the basics of soldering for off-the-shelf hackers. Breadboards are great for prototyping and proofs-of-concept while making it easy to connect everything together with short jumper wires. A lot of times you don’t need to solder anything if you use a breadboard.

If you’re designing more “permanent” prototypes, moving away from breadboards and on to all soldered connections gives a rugged, reliable and much more portable build. While it’s great to solder every connection in sight, you’ll still need to deal with the header connections on many DIY/Maker circuit boards.

This time I’ll share my technique for soldering small stranded and solid core wires to male header pins. The process makes it easy to plug a wire into an Arduino header. It also works for wires that still might need to go into a breadboard, without having to use a jumper. If you are new to soldering, it’s a great way to quickly gain valuable practice, while handling small, precise solder joints.

Soldering a small wire to a header pin seems obvious to experienced off-the-shelf hackers. Keep in mind that there are lots of newbies in our readership, diligently working their way over the “light an LED” hump. It’s good to pass on a few labor-saving tips now and again, to keep enthusiasm high and help with learning the hands-on craft.

From Breadboards to Pins

Lots of off-the-shelf hacker projects connect wires to printed circuit boards via headers.

For example, a full-sized traditional Arduino board has two rows of .1 inch (2.54 mm) female headers for connecting to the general purpose input/output, power and other interfaces. Hook up is as simple as pushing the end of a jumper wire into a header connection and plugging the other end into a hole on the breadboard.

You can also push the end of bare wire into the female Arduino connector. Sometimes I use bare wires in this manner if I don’t want the project to be a kludgey bird-nest of jumper wires. They tend to pull out, though if you move any of the boards or wires around. It is especially problematic for gadgets that need to be transported and demonstrated to audiences. For reliability and easy modding, soldering the wires to an individual male pin or a multipin header that can then plug into the female Arduino header is the way to go. Single male pins work great for single wires. Rows of male pin headers, with multiple wire connections work great too and help ensure wires are in the proper positions. Here’s how I solder a 24-gauge wire to a standard male 0.1 inch (2.54 mm) header pin.

I typically solder with the iron in my right hand and hold the roll of solder in the left.

Helping hands rig, solder, soldering iron and positioning

The Technique

Strip about 1/8 inch of the insulation from the wire you’d like to solder to the male header pin. Clip the wire into one side of a “third-hand” rig. This would be the left side, for me. If you really want to be spiffy check out this “quad-hands” device. Using a small soldering iron (25-watt or so) touch the hot tip briefly to the wire while simultaneously feeding in the end of the solder. It takes steady hands and a bit of practice to coat the tip of the wire neatly with solder. Don’t keep the iron on the wire too long or the insulation will shrink up the wire leaving a long bare space at the end. You might need to use side cutters to prune the wire back to my recommended 1/8 inch length of bare wire wetted with solder. Wetting a surface with solder is called “tinning”.

Next, clip the 0.1-inch male header pin into the other side of the third hand so the short side is pointed toward the wire. Use the same “touch the end of the iron and solder technique” to tin the short side of the header pin. That should be the side toward the wire. A single 0.1-inch male header pin can be snapped off of a larger chunk of header pins, as needed. I keep a ready supply in the old parts bin.

Multipin male header

Now you can adjust the third hand to position the wire end and header pin together so they solidly touch. Carefully, bring the tip of the soldering iron to the joint and ever so slightly touch it to the pin and wire. The solder should flow between the two and give a nice smooth result. It usually only takes a touch. Well, and a pretty steady hand. With practice, you won’t even have to add any solder with your other hand.

Clearly, I should have perhaps had one fewer cup of coffee before I shot the video.

Multiple wires can also be connected to a row of male header pins using the third hand, soldering iron and solder. I like to strip and tin all the wires and the matching male header pins before the final positioning. Joining the wire at each end of the header aids in getting the lengths right in the middle, particularly when making a cable. It is a bit more difficult to solder around previously joined connections. The following picture illustrates a multiwire/male header row pin connection.

Multiwire pin header and wires

Going Further

Soldering small wires to header pins might seem trivial and inconsequential. Your projects won’t be reliable and rugged without solid solder joints. Oh, sure everybody is moving to re-flow ovens and DIY printed circuit boards. Guess what? You still need to tin the tiny components that get re-flowed.

Adding the wire to header trick to your off-the-shelf hacker skill set will ensure your project works when you are in front of an audience and the pressure is on to perform. Using pluggable pins in your projects also makes it easy to take things apart for mods and re-purposing.

Catch Dr. Torq’s Off-The-Shelf Hacker column, each Saturday, only on The New Stack! Engage him directly for consulting and commissioned projects at doc@drtorq.com or 407-718-3274.

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