How can automotive wiring harness reduce the risk of poor terminal contact through structural design in a vibration environment?
Release Time : 2025-09-11
Automotive wiring harnesses require systematic structural design to reduce the risk of poor terminal contact in vibration environments. Core strategies focus on optimizing terminal structure, matching sheath design, strengthening fixing methods, and controlling the manufacturing process.
Optimizing terminal structure is fundamental to improving vibration resistance. Traditional single-contact terminals are prone to momentary disconnection due to contact load fluctuations during vibration. However, dual-contact or multi-contact designs significantly reduce the probability of contact resistance fluctuations by increasing the number of contacts in parallel. For example, one vehicle model improved contact resistance stability by 40% during vibration testing by increasing the number of terminal contacts from one to two. Furthermore, the terminal material's hardness and elastic modulus must be balanced. Phosphor bronze or copper alloys, due to their higher hardness, can reduce deformation under micro-vibration. The copper substrate should be plated with three layers (such as Sn-CuSn-Ni) to suppress plating diffusion and prevent oxidation corrosion caused by plating wear.
The matching design between the sheath and the terminal directly impacts contact stability. Sheath holes should incorporate guiding structures, such as funnel-shaped bevels, to guide the terminal for precise docking and minimize insertion deviation. For multi-hole housings, preferred types feature a power-assist mechanism. These have slower mating speeds and require vertical installation, reducing the risk of uneven force on the terminals. Furthermore, the dimensional tolerances of the housing and terminals must be closely matched to prevent terminal wobble caused by excessive clearance. For example, one supplier reduced the terminal contact failure rate by 25% by tightening the housing hole dimensional tolerance from ±0.2mm to ±0.1mm.
Strengthening the fixing method is key to reducing vibration transmission. Sufficient length should be reserved for the automotive wiring harness's fixing points on vibrating components to prevent strain on the harness caused by component movement. For example, a transition section of at least 200mm should be added at the junction between the engine and cabin wiring harnesses, and both ends should be fixed to the stationary end of the vehicle body to prevent powertrain vibration from being transmitted to the terminals. Furthermore, when selecting fixing clips, the outer diameter of the harness should be compatible with the clip type to avoid direct load-bearing on the clip. One fixing point should be provided at obtuse inflection points, two fixing points at right-angle inflection points, and sharp inflection points should be avoided through optimized routing.
Controlling the manufacturing process can eliminate potential risk points. Terminal crimping parameters should be optimized based on wire specifications, such as maintaining compression within 15%-25% to ensure a balance between mechanical and electrical properties. After crimping, cross-section testing should be performed to verify the tightness of the copper wire and terminal crimping to avoid increased contact resistance due to poor crimping. During assembly, vertical insertion should be prioritized to reduce the risk of male terminals skewing on the assembly line. For example, one automaker reduced terminal deformation by 18% during final assembly by increasing the male terminal insertion rate from 60% to 90%. Furthermore, electrical inspection stations should be equipped with high-precision vertical inspection modules to minimize inspection area dimensions and promptly detect and correct horizontal terminal skew.
Upgrades in materials and surface treatment technologies can enhance terminal durability. Plating thickness should be optimized based on material properties, such as keeping tin plating thickness below 1μm to prevent plating peeling due to micro-vibration. For high-temperature environments, materials with better stress decay resistance need to be selected. For example, phosphor bronze terminals can maintain stable connections below 125°C, while brass terminals are only suitable for scenarios below 80°C.