Wire wrap

From ArticleWorld

Wire wrap is a technique used to construct complex electronics assemblies in small numbers. It is a viable alternative to creating printed circuit boards when only a small number of units are required, or when only doing prototype work. Many electronic devices have been constructed using wire wrapping techniques, including radios, sonars and even computers. In fact, the Apollo Guidance Computer has been built using wire wrapping techniques.

Wire wrapped circuits are more reliable than PCB-based circuits, and less vulnerable to damage due to physical shocks and vibration. The connections are stronger and less damage-prone since they are not solder-based, and the electrical resistance is generally lower.

Parts

In general, the electronic parts are plugged into sockets, which are glued to epoxy plates using silicone glue. The sockets have square posts placed at regular intervals, with hard-drawn premium posts.

Another commonly used tool is the wire wrap tool. This is used by rapidly twisting it two or three times, wrapping the wires around the post, with a number of bare wire turns wrapped atop it. This allows for a reliable assembly, and also allows manual wire wrapping to be used in repairs.

Placing wires on the board can be done in three ways:

• Manual wire wrap, using small, pen-resembling wrapping tools. Manual wire wraps can be easily repaired without wearing out and are quite reliable.

• Semi-automated wire wrap, which involves computer-controlled wire-wrap guns. The wires are inserted manually, but the wrapping is computer-controlled. This is commonly used, as it can place twisted pairs, allowing prototypes of high frequency computers and radar systems.

• Automated wire wrap, which is done using completely computer-controlled wire wrapping tools. Modern wire wrapping programs automatically optimize the wire placement, in order for the assembly to take less time and manual repairing to be done more easily.