Why Does The Contact Resistance Increase Abnormally After Cold Pressing?

Many people think that as long as the wires are properly crimped, everything is fine when making circuit connections. Actually, that's not the case. Sometimes, the crimp contact looks quite sturdy, but when you test its resistance, the value is frighteningly high. This surge in resistance is often related to cost-cutting in unseen details during manufacturing.

Insufficient material thickness affects the plastic deformation of the cold-pressed needle.

The performance of crimp contact pin largely depends on the substrate. If the copper purity is insufficient, or if the wall thickness is significantly reduced, the force applied by the crimping clamps cannot be evenly distributed. Where physical cold welding and a hermetically sealed connection should occur, the material's strength is insufficient, leading to tiny gaps at the contact surface.

The cross-sectional compression ratio is not up to standard.

The core of crimping is to make the conductor and contact socket crimp mesh tightly interlock. Material reduction will cause the cross-sectional compression ratio to deviate from the standard value.

• Increased Gaps: Insufficient crimping allows air to enter the gaps, and an oxide layer quickly covers the contact surface.

• Unstable Resistance: When current flows, the effective conductive area decreases, causing the resistance to fluctuate wildly.

• Overheating Risk: High contact resistance leads to heat buildup as current flows, potentially causing the interface to burn out over time.

Surface plating shrinkage accelerates oxidation of cold-pressed needles

Some crimp contact female needles have a shiny surface, but the gold or tin plating layer is actually as thin as a sheet of paper. During crimping, the immense pressure of the clamping jaws directly wears away this protective film. The exposed copper, now without plating, can experience a significant increase in resistance within months, even in slightly humid environments.

Crimping Die Wear and Cold Press Pin Compatibility

Besides the material itself, tool compatibility is crucial. If worn-out dies are not replaced, or incompatible cold press pins are used, the resulting shape will be uneven. This uneven deformation in the physical structure is the direct cause of soaring contact resistance. During installation, paying close attention to the deformation curvature of the cold press pin can usually indicate the quality of the connection.