Investigation of Production Requirements for Solderless Wire Wrapped Electrical Connections

A solderless wire wrapped electrical connection consists of tightly wrapping solid bare wire around a stationary terminal to produce a durable pressure connection. Properly made, the wrapped connection is a permanent, reliable electrical connection that can be produced faster than soldered connections. The elimination of solder and heat detriments are distinct advantages over the soldered connection. Wire wrapping lends itself to automation, and connections can be easily made on closely spaced terminals. While it is a mechanically strong connection, an individual connection is easily removed, simplifying modification and repair. However, this may be less of an advantage in multi-level wrapping. The increase in complexity of electronic equipment during the last decade has presented industry with some unique production problems. Not the least of these has been the great increase in the number of electrical connections. The need for speed in making this many connections, without decreasing quality, prompted IBM to expend considerable effort in identifying the variables that affect solderless wire wrapping connections in order to define the controls needed in production. At the present time, these connections are widely used by IBM in both commercial and military applications, and over 100 million solderless wrapped connections were made by IBM in 1960. The use of the solderless wrapped connection has grown steadily since the Bell System first made the new connection public in 1952. Extensive laboratory tests, performed principally byBell Laboratories, and field experience have verified the reliability of the connection. This paper describes the effect of the variables involved in the wire wrapping process which were determined from the results of laboratory tests and manufacturing experience and the process controls required to assure the quality and reliability of production connections. To meet process requirements consistently, the many variables inherent in the solderless wire wrapping process must be considered. These variables will be discussed under the major variable factors involved in the process.