Wire wrap

Wire wrapping is unusual among other prototyping technologies since it allows for complex assemblies to be produced by automated equipment, but then easily repaired or modified by hand.

Wire wrap construction can produce assemblies that are more reliable than printed circuits: connections are less prone to fail due to vibration or physical stresses on the base board, and the lack of solder eliminates soldering faults such as corrosion, cold joints and dry joints.

The connections themselves are firmer and have lower electrical resistance due to cold welding of the wire to the terminal post at the corners.

Wire wrap was used for assembly of high frequency prototypes and small production runs, including gigahertz microwave circuits and supercomputers.

Manually wrapped wires were common in early 20th century point-to-point electronic construction methods in which a strong connection was needed to hold the components in place.

Keller began manufacturing the tools in 1953, and subsequently obtained a license from Western Electric allowing sale of the technology on the open market.

A correctly designed wire-wrap tool applies up to twenty tons of force per square inch on each joint.

Premium posts are hard-drawn beryllium copper alloy plated with a 0.000025 in (630 nm) of gold to prevent corrosion.

30 gauge (~0.0509mm2) silver-plated soft copper wire is insulated with a fluorocarbon that does not emit dangerous gases when heated.

In space-rated or airworthy wire-wrap assemblies, the wires are boxed, and may be conformally coated with wax to reduce vibration.

[citation needed] Automated wire-wrap machines, as manufactured by the Gardner Denver Company in the 1960s and 1970s, were capable of automatically routing, cutting, stripping and wrapping wires onto an electronic "backplane" or "circuit board".

These machines included very large hydraulic units for powering the servos that drove the ball screw mounted "A" and "B" drive carriages, a 6 ft (1.8 m) tall electronics cabinet loaded with hundreds of IBM control relays, many dozens of solenoids for controlling the various pneumatic mechanical subsystems, and an IBM 029 card reader for positioning instructions.

Gone were the hydraulic units, in favor of direct drive motors to rotate the ball screws, with rotary encoders to provide positioning feedback.

This generally provided better visibility of the product for the operator, although maximum wrap area was significantly less than the horizontal machines.