Analysis of Gold Plating Abnormalities in Pogopin Spring Pins

Time：2025-07-17 Views：1 source:

Gold plating abnormalities in pogopin spring pins, such as peeling, porosity, or uneven thickness, stem from issues in pre-treatment, plating processes, or material compatibility. Plating peeling is often caused by poor surface preparation: oil, oxides, or fingerprints on the pin surface prevent adhesion. For example, if beryllium copper pins are not properly cleaned with ultrasonic degreasing (using alkaline solutions at 60-70°C), the gold layer will lift after thermal cycling. Another cause is excessive internal stress in the plating—thick gold layers (>1μm) without a nickel underlayer can crack during spring compression, leading to peeling.

Porosity in the gold layer allows moisture and corrosive agents to reach the base metal, causing under-plating corrosion. This occurs due to low current density during plating (insufficient metal ion deposition) or contaminated plating baths (high levels of impurities like iron or copper). Porosity is detectable via a salt spray test, where white corrosion spots appear within 24 hours instead of the standard 48+ hours for parts.

Uneven thickness (variation >20% across the pin surface) results from uneven current distribution during plating. Geometry plays a role: sharp edges or small gaps in the jig cause current concentration, leading to thicker plating at tips and thinner at crevices. Using auxiliary anodes or adjusting the plating bath’s pH (typically 4.5-5.5 for gold cyanide baths) can mitigate this. Additionally, improper racking—pins touching each other—creates shadow areas with no plating, a critical defect in high-reliability applications like medical devices. Addressing these issues requires strict process control: pre-treatment validation, regular bath analysis, and jig design optimization.