A Lost Art: Wire-Wrapping

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For this week's Featured Book, I wanted to find something on wire-wrapping. Although I was not successful at finding a book currently in publication that is dedicated to wire-wrapping, I did find a great page on Wikipedia full of information and great high-res pictures. There are plenty more resources if you do a Google search.

Wire wrapping (w/w) used the be a very popular method for prototyping circuits when DIP and SIP packages dominated the electronics landscape. If done properly where wraps were placed on posts in order to make changes easier and where care was taken to avoid crosstalk from long parallel signals runs, w/w was useful at frequencies into the tens of megahertz, even with digital circuits. I personally have wire-wrapped more than a hundred boards both as engineering prototypes and as deliverable assemblies for military equipment. A well-done w/w board can look like a work of art.

Wire-Wrapped Z80 Computer Backplane 1977 (Wikipedia photo) - RF Cafe

There used to be machines (maybe there still are) that automatically do the wire wrapping based on a routing file. Some early schematic layout software had an option to output a wire-wrap file as well as a standard Gerber file for PCB fabrication. Wire wrapping is still a very useful option for breadboarding today even with the predominance of surface mount parts because SMD-to-DIP adapter products like Surfboards, SparkFun, Futurlec, SchmartBoards, Abra, and many others are available. Most of the electronics distributors sell wire-wrap backplanes, DIP sockets, SMD-to-DIP adapter/breakout boards, w/w tools and wire, etc.

You might be inclined to think that wire-wrapped connection is not very secure or high quality, but the fact is that when done properly, each complete wrap around the square, sharp-edged post provides four independent low-resistance, gas-tight contacts. The military and aerospace industry have published volumes on the science behind wire wrapping and on acceptable methods for performing it, as well as manufacturing specifications for the w/w posts, wire and its insulation, and the tools used to attach and remove wraps to/from posts.