Upgrading of wire harness processing technology: from material selection to breakthrough in shielding technology

Material selection

Conductor material: High-purity copper materials, such as 5A grade oxygen-free copper with a conductivity of ≥98%, are preferred. Tinning treatment can prevent oxidation, reduce resistance, and improve the efficiency of power transmission. In situations where weight is sensitive, aluminum conductors or aluminum-based alloy conductors can be considered, which can achieve light weighting, but their connection reliability needs to be paid attention to. In the field of high-voltage wire harness for new energy vehicles, copper alloy conductors have become a trend with their good conductivity and mechanical properties.

Insulation material: select based on the operating environment and performance requirements. PVC is wear-resistant and oil-resistant; PE can withstand high temperatures up to 125℃; PTFE has corrosion resistance; silicone rubber insulation material is suitable for high-temperature environments. In automotive wire harnesses with high requirements, to meet the ISO 26262 functional safety standard, there are stricter regulations for the electrical properties and flame retardancy of insulation materials.

Connector materials: brass terminals plated with gold or nickel to prevent rust, PA66 sheathing for impact resistance, and EPDM rubber seals for water resistance (e.g. IP67 grade). These materials ensure reliable connections and stable transmission of signals and power.

Shielding technology aspects

Upgrading of shielding materials: Development from single shielding material to multi-layer composite shielding, such as a “sandwich” structure of inner layer aluminum-coated polyester film (thickness 12μm) + middle layer copper braided screen (120 mesh) + outer layer conductive coating, significantly enhancing shielding efficiency up to 120dB. Explore the application of new shielding materials, such as conductive polymers, nano-coatings, etc., to enhance the suppression capability of high-frequency electromagnetic interference.

Innovative shielding structure design: setting up stress buffer structures, such as adding a 0.3mm silicone buffer layer between the shielding layer and the insulation layer to reduce thermal stress; adopting a wavy shielding net woven (amplitude 1.2mm), allowing ±0.8mm of free expansion and contraction, to reduce the decrease in shielding performance caused by the mismatch of thermal expansion of materials. Compensation design is carried out at the connector, such as adding a conical elastic contact plate (compression amount 0.5mm) at the end of the plug pin, so that the contact pressure fluctuation rate ≤5%; a disc spring is built into the shielding shell to compensate for the 0.25mm thermal deformation amount.

Process improvement for shielding: Advanced precision welding techniques, such as laser micro spot welding (welding point spacing 0.8mm), were adopted to enhance the welding strength to 300N/mm²; the ultrasonic crimping process was used to ensure that the contact resistance of the shielding layer ≤5mΩ with a fluctuation rate <1%. The shielding layer processing process was strictly controlled, such as operators wearing goggles to prevent the shielding wire from splashing; precise control of the shielding wire scattering and outward flipping to avoid missing wires or piercing the wire insulation.

Enhanced detection and monitoring: Integrated TDR (1cm resolution) for online impedance monitoring, real-time detection of shielding continuity, with positioning accuracy ±2mm; Real-time X-ray imaging using 450kV micro焦点 CT (5μm resolution) to capture micro cracks in the shielding layer >10μm; Thermal simulation predictions using software like ANSYS to预dict key node temperature gradients (error <3℃), optimizing shielding structure.