Surface Treatment Processes for Brass Pins: The Application and Optimisation of Gold Plating Techniques

Surface treatment is a critical post-processing step in precision metal manufacturing, directly affecting a product’s electrical conductivity, corrosion resistance and aesthetic quality. As the core surface treatment process for high-end connector pins, gold plating offers excellent electrical conductivity, oxidation resistance and low contact resistance, making it key to ensuring the long-term reliability of connectors.
Traditional direct current electroplating suffers from issues such as uneven gold layer distribution, pronounced edge effects and high porosity. In the deep holes and grooves of micro-pins, weak plating areas are prone to occur, affecting product consistency. The introduction of pulse electroplating technology has resolved this challenge. Compared to DC electroplating, pulse electroplating periodically interrupts the current, resulting in more uniform diffusion and deposition of gold ions on the workpiece surface, effectively eliminating tip and edge effects

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To accommodate pins of varying geometries, the industry has developed multiple sets of pulse parameter formulations: for standard cylindrical pins, a symmetrical square-wave pulse is used at a frequency of 100 Hz with a duty cycle of 1:9; For irregularly shaped pins with grooves, asymmetric pulses combined with ultrasonic assistance are employed to ensure deep plating capability

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The quality inspection system includes: non-destructive measurement of gold layer thickness and composition using an X-ray fluorescence spectrometer, with an accuracy of 0.01 μm; cross-sectional analysis via a metallographic microscope to observe coating density and interfacial bonding; Neutral salt spray testing to assess corrosion resistance; micro-ohmmeter measurement of contact resistance to ensure that the resistance value after gold plating does not exceed 110% of the substrate’s resistance

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Gold-plated pins have been deployed in large-scale production across multiple high-end sectors. In the automotive electronics sector, they are used in critical components such as engine control units and ADAS sensors, operating within a temperature range of -40°C to 150°C and with a mating cycle life exceeding 5,000 cycles; In the telecommunications equipment sector, they are used in 5G base station RF connectors, with a frequency range of DC–6 GHz and a voltage standing wave ratio (VSWR) of less than 1.2; in the medical equipment sector, they are used for conductive connections in implantable devices and have passed biocompatibility testing.
Leading companies in the industry are continuously optimising process parameters and exploring cutting-edge technologies such as nano-composite plating to provide customers with surface treatment solutions offering higher added value.