In EV battery packs and energy storage systems (ESS), the interface between BMS slave boards, battery cell terminals, and power busbars directly dictates voltage sampling accuracy (<1mV) and system longevity. Hardware selection must satisfy electrical, metallurgical, and mechanical vibration criteria simultaneously.
Electrical and Mechanical Demands on BMS Hardware
BMS board hardware must sustain continuous micro-sampling currents while withstanding high-current surge events during short circuits. Operating environments demand thermal cycling from -40°C to +125°C and compliance with ISO 16750-3 automotive swept-sine vibration standards.
Cu-Al Eutectic Transition Busbars for 56% PACK Weight Reduction
Prismatic battery cells and busbars frequently use aluminum, whereas PCB sampling boards and relays use copper. Direct bolted contact between copper and aluminum causes severe galvanic corrosion under humid conditions.
CUNECTRA liquid-solid eutectic cast Cu-Al busbars form a 300~500nm nanoscale Al₂Cu/Al₄Cu₉ metallurgical bond with peel strength >148 N/mm (12x national standard). The copper face supports 260°C reflow and laser welding; the aluminum face connects via ultrasonic bonding or bolts, reducing weight by 56% while eliminating galvanic corrosion.
- Peel Strength: >148 N/mm (GB/T 32468 standard requires ≥12 N/mm)
- Density & Weight: 3.94 g/cm³ (44% of pure copper density)
- 90° Bend Capability: Crack-free bending at R=0.5t with zero interface flaking
- Certified Testing: 51-size ampacity database verified by Tianjin Quality Inspection & STRI
Three Defenses Against Galvanic Corrosion
For outdoor ESS container and automotive salt-fog conditions, our interconnects utilize three defensive barriers: an atomic-level pore-free eutectic interface, chemical passivation with epoxy encapsulation at cut edges, and 3~5μm electroplated matte tin/nickel coating, passing 96-hour neutral salt spray (NSS) testing.
Automotive Vibration Standards (ISO 16750-3) & Anti-Loosening Geometry
PCB screw terminals incorporate anti-rotation ribs and knurled retention teeth, maintaining preload torque relaxation below 5% under 10~2000Hz random vibration spectra while keeping contact resistance below 0.2 mΩ.