In new-energy vehicle battery packs, overmolded copper busbars serve as core components for high-voltage current transmission.
Through insert-molding, high-performance engineering plastics are tightly bonded to the copper conductor to form an integrated
conductive structure. Their key functions include:
High-voltage conduction: High-purity copper enables stable, high-current transmission.
Reliable insulation: The molded plastic layer prevents HV leakage and ensures vehicle electrical safety.
Structural robustness: The encapsulation protects the conductor from mechanical stress and vibration, maintaining installation accuracy.
Space optimization: Replacing distributed wiring harnesses improves battery-pack space utilization and supports automated assembly.
Material Requirements for Overmolded Copper Busbars
Insulation Performance: Must meet HV insulation standards with stable dielectric strength and reliable breakdown voltage.
Toughness: Improved impact resistance to prevent brittle failure in low-temperature or high-vibration environments.
Reinforced Stiffness: Glass-fiber–reinforced formulations to maintain structural strength and withstand long-term mechanical loads.
High-Temperature Resistance: Continuous operating range of 120–180 °C to match the thermal conditions of EV battery packs.
High Flowability: Supports thin-wall, complex overmolding with reduced risk of sink marks, short shots, and other molding defects.
Metal–Plastic Bonding Strength: Optimized resin formulation to ensure strong adhesion to copper inserts with no delamination risk.
For the demanding requirements of busbar insulation components, RHI’s PA66+GF30 (30% glass-fiber reinforced, halogen-free flame-retardant) material delivers outstanding suitability:
Excellent Electrical Insulation: Provides stable high-voltage insulation protection and meets automotive electrical safety standards.
Superior High-Temperature Performance: Supports continuous use at 150–180 °C with a heat deflection temperature above 270 °C, maintaining stiffness, strength, and dimensional stability under elevated temperatures.
Low Expansion & Creep Resistance: Low CTE and excellent creep resistance ensure precise dimensions and secure retention of copper conductors across wide temperature ranges and long-term loading.
High Flame Retardancy: Halogen-free FR formulation achieves UL94 V-0 at 0.8 mm, effectively preventing flame propagation.
Balanced Mechanical Properties: Combines high rigidity and strength with necessary toughness for structural support and impact resistance.
High Flowability: High-flow PA66 grade suitable for complex, thin-wall insulation geometries, improving molding efficiency and yield.
Reliable Metal–Plastic Bonding: Optimized for insert-molding processes, forming a strong and durable interface with copper conductors for long-term service conditions.
