Crimp connection

A crimp connection is a type of solderless electrical connection.

Simple crimp connectors are typically used to terminate stranded wire. Specialised crimp connectors are also used, for example as signal connectors on coaxial cables in applications at high radio frequencies (VHF, UHF).

Simple crimp connectors

They fulfill numerous uses, including allowing the wires to be easily terminated to screw terminals, fast-on / quick-disconnect / spade-foot type terminals, wire splices, various combinations of these. A tube-shaped connector with two crimps for splicing wires in-line is called a butt splice connector. Crimp-on connectors are attached by inserting the stripped end of a stranded wire into a portion of the connector, which is then mechanically deformed / compressed (crimped) tightly around the wire.^[1] The crimping is accomplished with special crimping pliers. A key idea behind crimped connectors is that the finished connection is gas-tight.

Crimped connections fulfill similar roles, and may be thought of similarly, to soldered connections. There are complex considerations for determining which type is appropriate - crimp connections are sometimes preferred for these reasons:

• Easier, cheaper, or faster to reproduce reliable connections in large-scale production.
• Fewer dangerous, toxic or harmful processes involved in achieving the connection (soldered connections require aggressive cleaning, high heat, and possibly toxic solders).
• Potentially superior mechanical characteristics due to strain relief and lack of solder wicking.

Many classes of crimped connections exist. Some of the most common are:

Barrel

• Wire to be terminated is inserted into a cylindrical section of metal, then crimped, with the resultant shape somewhat of an oval.
• To the layperson, perhaps the most common type. Readily available at retail (Radio Shack, Home Depot, Fry's, etc.).

Open-barrel

• refers to the pre-crimp crimp section having a U or V shape
• More robust connection than barrel-type and thus more common in industrial and automotive applications
• Simpler to automate since wire can be laid in the un-crimped connector versus barrel which requires funneling the wire into the barrel to prevent strands from catching.
• Types:
  • F crimp: Both wire and insulation (if optional insulation support is present) are crimped from U to B shape.
  • Weather-Pack/Metri-Pack: common brand-name crimp connectors designed for use in sealed housings. Wire is crimped from U to B shape, insulation from U to 'O' shape.

Specialised crimp connectors

Crimp connections are used typically to fix connectors, such as BNC connectors, to coaxial cables^[2] quickly, as an alternative to soldered connections. Typically the male connector is crimp-fitted to a cable, and the female attached, often using soldered connections, to a panel on equipment. A special power or manual tool^[3] is used to fit the connector. Wire strippers which strip outer jacket, shield braid, and inner insulation to the correct lengths in one operation^[4] are used to prepare the cable for crimping.

References