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How to Specify Insulation Displacement Contacts for Harsh-Environment Applications
Tom Anderson, Connector Product Manager, AVX Interconnect
Not all insulation displacement contacts (IDCs) are created equally. As with any contact system, the ultimate functionality and reliability — especially in automotive, transportation, and harsh industrial markets — comes from specifying the highest performance base metal and matching it up with an optimized contact geometry or design.
In today’s market, IDC contact materials range from brass, which is at the lower end of the spectrum with regard to both cost and performance level, up to phosphor bronze, which consistently provides the contact integrity needed in demanding, harsh-environment applications. Brass is very common in larger, typically higher current carrying contact systems, such as terminals and switches, but experiences stress relaxation in smaller, higher- precision IDC contact geometries. Phosphor bronze is better suited to providing and maintaining higher strength and contact forces in severe environments without relaxation. Yet, during the wire insertion process, phosphor bronze has enough beam elasticity to ex in order to avoid damaging or cutting into the conductor, preventing long-term reliability concerns.
Optimizing the contact stamping design to match the material properties is the second and nal critical step for ensuring ultimate contact functionality and reliability. When contact systems promote that they can accept a broad range of wire gauges, for example 18–26AWG, it typically means that they employ softer brass base metal materials, as these are exible enough to accommodate several different wire diameters. However, in order to maximize the performance and robustness of IDC contacts in harsh applications, the contact wire slot must match a speci c wire gauge. This precise contact stamping design deforms the conductors during the wire insertion process and creates an impregnable, gas-tight, cold-welded connection between the wire and the contact that can survive in even the harshest environments.
This particular marriage of metal and design has allowed IDC contact systems to extend their capabilities beyond the termination of traditional multi-stranded insulated wires. Phosphor bronze IDC contacts with contact wire slots matched to speci c wire gauges can now reliably terminate to both insulated and uninsulated single conductor wires, and even solid component leads. Additionally, the impregnable, cold-welded termination they achieve allows the connection to be overmolded or potted, making them an ideal solution for harsh applications in which
Figure 1: A generic view of an electrolytic capacitor carrier in which the IDC termination to the capacitor lead provides the connection to the PCB.
modules need to be waterproofed or otherwise protected from the environment.
One example of terminating an IDC contact to solid leads is illustrated in Figure 1. Due to the inherent reliability designed into these robust IDC contact systems, the automotive market has embraced electrolytic capacitor holders in which the IDC termination to the capacitor lead provides the connection to the printed circuit board, and has employed them in a variety of automotive safety and engine management systems.
Also unique to this contact technology is its ability
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