A method of creating prototype electronics boards that is more specific, more permanent, and less elecronically noisy than using a protoboard, and less messy, dangerous, and carcinogenic than soldering. All electronic components that are to be used in the board are mounted in special mounts that have long, stiff wire prongs beneath. These mounts are inserted into a generic breadboard, and prongs are connected to each other by wrapping thin wires around the legs.

To wrap one end of a wire:

  1. Strip off about .75 cm from the end of the wire.
  2. Take out your overpriced (because the patent on the design is aggressively enforced) wire wrap tool.
  3. Insert the bare wire into the guide on one side of the tool's shaft.
  4. Guide the tool's shaft over the prong you wish to wrap.
  5. Spin the tool gently, keeping a gentle downward pressure on the prong. If you do it right, wire should play out from the guide, and form a nice, tight coil around the prong.
    • If you are too gentle in your twisting, your wire won't be tight enough.
    • If you are too forceful in your twisting, your wire will break.
    • If you keep too much downward pressure on the prong, your wire will wrap over itself, then break.
    • If you don't keep enough downward pressure on the prong, your wire coil won't be tight, and may come off easily.
  6. Now wrap the other end of the wire around wherever you want it to be. Make sure when you cut the wire, you leave enough play to get the wire onto the end of your tool!
Wire wrapping is a tricky craft to learn, but after you've made your third board or so, it should come naturally.

There are a number of drawbacks to wire-wrapping. Among them:

  1. You need very thin, very fragile wire to do it. If you want to create a proto-board that controls, say, an electric motor, you may want to consider solder instead.
  2. The more connections you have, the more spaghetti-like the underside of your board will be. Using black wire for your ground lines and red wire for your power lines is a must. Consider using other colors as warranted.
  3. The fact that you are wrapping on the opposite sides of your chips means that you have to mentally 'flip' everything on the board when you make connections. The potential for error is great, and unless you verify every connection immediately after it is made, you may spend unnecessary amounts of time hunting down that bad connection.
I find that the best way to to a wire-wrap board is to draw out the physical chip diagram and connections in ink on thin paper, then flip the paper over and trace in the same connections through the paper with pencil. Then, as I wrap the board, every time I complete a connection, I trace over it with pen. Also, I wrap all the ground connections and power connections first, since it gives a hint as to the layout of the chips (a forest of prongs without any reference is kind of intimidating).
For a good example of the uses of wire wrapping, see the wonderful book The Soul of a New Machine by Tracy Kidder. In it, he chronicles the development of the Data General Eclipse MV/8000 computer, code-named Eagle.

In the book, engineers working on the new machines take turns wire-wrapping boards and debugging them when, inevitably, the various nasty (and sometimes highly amusing) faults of a developmental box surface. bitter_engineer's excellent description in fact made those scenes from the book clearer.

A point worth making.

bitter_engineer says above "A method of creating prototype electronics board". And he's correct, that for most people, their exposure to wire wrapping will being when prototyping electronic circuits.

However, in some high reliability systems - such as TelCos - Wire Wrap is used for permanent connections. Why?

All forms of connection involve a physical joint. In most connection systems, this is effectively a spring holding two pieces of metal together. In the case of solder, a strong electrical bond is formed by the solder but the physical bond is weak. And in either case, there are only a few (2-4) actual points of contact between the two pieces of metal. (Even if two "flat" pieces of metal are touching, due to surface imperfections, there may still be not many true points of contact).

With Wire Wrapping, you wrap a wire round a thick pin with a square cross section. And you may wrap it, say, 6 times. This means that for each time the wire goes round the pin, it makes contact at each corner of the square. 24 points of contact.

Hence these are seen as very reliable and are often used for permanent connections.

Source: My employer makes hardware for TelCo's!

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