If you believe this 1953 advertisement in Radio & Television News
magazine, engineering at Bell Telephone Laboratories invented the
wire-wrapping process. A little additional research shows that indeed it was
a Bell Telephone engineering team led by
Arthur Keller who developed the method and a wire-wrap tool to do the
job. Field technician needed a fast, durable, and reliable electrical
connection when making hundreds or thousands of splices at relay stations
and while up on telephone poles. The key to making a good wire-wrap connection is sharp corners on the
wrapping post so that the corner pushes through any oxidation or contaminant
on the bare wire. NASA and the Department of Defense (DoD) have exacting
workmanship standards to guarantee a rugged, durable electrical connection
with low resistance, and imperviousness to contamination. In fact, properly
formed wire-wrap connections are considered to be gas-tight. See NASA's "Discrete Wiring Solderless Wrapped Electrical Connections - Wire-Wrap"
for more information.
A 1958 ad told of Bell Labs' development of
thermocompression wire bonding.
Bell Telephone Laboratories Advertisement
A New Twist in Telephony
A solderless connection, enlarged 15 times. Connections are more uniform
than soldered ones and only half as bulky.
For years the accepted way to connect wires to telephone apparatus was with
solder. Now, Bell Laboratories engineers have discovered how to make connections
faster and better - without solder.
Solder, they reasoned, wouldn't be needed if wire and terminal could be kept
tightly pressed together. But, for economy, this had to be done with the wire
alone - without complicating screws and springs.
They found the answer in using a properly dimensioned terminal with sharp
edges ... whipping the wire around it under high tension. The terminal bites
into the wire, locking it securely into position. Thereafter the squeezed edges
maintain a contact pressure of at least 15,000 pounds per square inch - even
under vibration that cracks soldered joints.
The new connections can be made in half the time - a big money-saver in the
billion connections that Western Electric makes each year for the Bell System.
It's another example of the way Bell Telephone Laboratories works continually
to keep costs low.
Bell Telephone Laboratories
Improving Telephone Service for America Provides
Careers for Creative Men in Mechanical Engineering
Cross section of solderless connection. Note terminal biting into wire. In
a six-turn connection there are at least 20 clean contact areas impervious to
moisture and corrosive gases, offering current a low resistance path.
Power tool whips wire on terminal in fraction of a second. There is no heat
which could damage miniature components ... no dropped solder or wire clippings
to cause trouble later.
Posted January 24, 2019