By Ryan Winters
No need for a back beat. I'm not going to break out in rhyme. I'm talking about the application of wire wrapping used in electronic design. I'm proof that you don't have to be an Electrical Engineer to love learning new electronics skills. It all started when I was designing a prototype that needed to connect the pins from a LED matrix to an array of LED driver ICs. Over 144 point-to-point connections would require a ton of soldering. But then a casual comment from a colleague changed my life, "why don't you use wire wrap?"
Wire wrap? What the heck is that? I have seen wire wrapping tools in the catalog, but I had no idea that someone could effectively wrap 30 AWG around the tool. A quick Google search defined the technology and pointed me to a quick tutorial where I learned the basics. Piece of cake really; something anyone could learn in two minutes and master in a few more with some practice.
Wire wrapping is great for prototypes because it's easy to make point-to-point connections and to repair them.
Because no soldering is involved, the possibility for cold or dry joints is eliminated and so are the fumes.
Wire wrapped connections are actually more reliable than soldered connections because of the amount of contact the wire makes with the post. On a square post, a single turn of wire actually makes four contacts with the post at the corners. The wrapping tool literally applies tons of force per square inch on each joint, nearly cold welding the wire to the post. A properly made wire wrap connection will have 0.5 to 1.5 turns of insulated wire at the bottom serving as a strain relief (also called modified wrap) and have six to seven turns of stripped silver-plated wire wrapped around the post, essentially making 24 to 28 air-tight connections.
For starters, you need wire wrap (most commonly 30 AWG silver-plated copper wire with Kynar™ insulation in a variety of colors), a wire wrapping/stripping tool, and preferably some machine tooled wire wrap sockets. While you can wire wrap just about any pin, machine tooled wire wrap sockets provide a 0.025" square post specifically designed for wire wrapping tools, and the connections will be much more secure. You may also find it more than helpful to utilize wire wrap socket ID markers. Because all of the wrapping is done from the underside of the socket, the ID markers label the pins so you make the right connection.
To start, strip about an inch of insulation off the wire.
There are two holes in the tip of the wrapping tool. The hole at the center is for the post to be wrapped, while the hole at the edge is designed for the stripped wire to be fed into it plus a little bit of insulation.
Lower the wrapping tool onto the post you wish to connect, and keep the insulated part of the wire in place with a fingertip. While keeping the other end of the tool in the palm of your hand, twist the wrap tool clockwise about six times to complete the wrap (the butt end of the tool is actually loose to facilitate twisting the tool without pinching your skin). Lift the tool off the post and Voila!
The square posts of the machine tooled sockets can actually accommodate three wire connections on the same post. There are additional benefits to wire wrapping with the first being no soldering! I don't have much lab space, and soldering can be a stinky process. Wire wrap is portable which means you can wrap wire while sitting on the couch watching TV or at your cubicle at work. It's also lead-free for all us greenies, and if you make a mistake, simply unwrap the wire and redo the connection. Next time you're transferring a breadboard project to a protoboard, give wire wrap a whirl.
I used this technique when creating my solderless prototype matrix for my QR code project.
Build Your Own Programmable LED QR Code
Ryan Winters is a Product Manager at Jameco Electronics. His hobbies include working on cars and computers, fiddling with electronic gadgets, and learning robotics and now, wire wrapping.