Oxygen-free copper (TU1/TU2, OF copper) features extremely low oxygen content (TU2: oxygen ≤0.002%, copper purity ≥99.95%), conductivity close to 100% IACS, no hydrogen embrittlement risk, excellent thermal conductivity and ductility. It is the preferred busbar material for 800V high-voltage platforms and high-power fast charging in new energy vehicles, widely used in high-current main high-voltage circuits of vehicles, replacing conventional T2 red copper for high-reliability scenarios.

✅ Five Core Application Positions

1. Power Battery Pack (Largest Consumption)

• Busbar connection between cells and modules, inter-module busbars, and main positive/negative output busbars from modules to Pack.

• Rigid oxygen-free copper busbars for fixed-position current collection; laminated flexible oxygen-free copper busbars absorb vehicle vibration and thermal expansion/contraction to prevent fracture.

• Advantages: Low resistance, low temperature rise under high fast-charging current; oxygen-free material avoids hydrogen embrittlement at high temperatures and improves battery safety; nickel or silver plating on surface reduces contact resistance and enhances salt spray corrosion resistance.

2. Inside Motor Controller (Inverter)

• Current-collecting busbars between IGBT power modules, DC-link capacitors and three-phase output terminals (often low-parasitic-inductance laminated busbars).

• Connect three-phase terminals of inverter and drive motor; flexible copper busbars buffer vibration displacement of motors.

• 800V platforms impose strict requirements on inductance and temperature rise. TU2 oxygen-free copper is preferred to cut switching loss and suppress electromagnetic interference.

3. High-Voltage Distribution Unit (PDU)

The core of vehicle high-voltage power distribution. Conductive connections for main circuit input, fuses and contactors, distributing power to high-voltage accessories including OBC, DC-DC, PTC and air-conditioning compressors.

4. On-Board Charger (OBC) & DC-DC Converter

Conductive busbars for internal power circuits, AC-DC conversion and high-low voltage conversion. High-power fast-charging models extensively adopt oxygen-free copper busbars to control heat generation and sustain continuous high-power charging.

5. Charging Ports & High-Voltage Accessory Circuits

Conductive busbars inside DC fast charging guns, high-voltage connections for PTC heaters and electric compressors; partial vehicle high-voltage equipotential grounding busbars.

✅ Selection Basis: Oxygen-Free Copper vs Conventional T2 Red Copper for NEVs

1. Ultra-low oxygen content, no hydrogen embrittlement: Under long-term high temperature and humid onboard environment, conventional red copper tends to crack when exposed to hydrogen at high temperature. Oxygen-free copper avoids such failure risk and adapts to long-cycle vehicle vibration.

2. Higher conductivity, lower resistivity. It can carry larger current with the same cross-section and generates less heat, suitable for ultra-large fast-charging current of 250A~600A.

3. Better ductility, stable bending, stamping and multi-layer diffusion welding performance, ideal for flexible connection busbar processing.

4. Excellent thermal conductivity, quickly dissipate heat generated by high current and reduce thermal runaway risk.

Simple distinction: Many low-cost 400V vehicles adopt T2 red copper; 800V high-voltage platforms, high-rate fast charging, premium models and long-lifetime requirements usually upgrade to TU2 oxygen-free copper (TU1 has higher purity, adopted for ultra-high-end scenarios).

✅ Surface Treatments (Standard for New Energy Vehicles)

• Nickel plating: Inside battery packs, corrosion resistance and good adhesion for insulation coating.

• Silver plating: High-current plug-in terminals and inverter contact surfaces for minimum contact resistance.

• Insulation coating: Dip coating, heat shrink tubing, PA66/PPS injection molding, meeting high-voltage insulation requirement UL94 V0 flame retardant.

✅ Structural Classification

1. Rigid oxygen-free copper busbar: Bent and punched for forming, fixed installation, used in battery modules and PDU interior.

2. Multi-layer laminated flexible oxygen-free copper busbar: Diffusion welding of thin oxygen-free copper sheets, deformable to absorb vibration, used for module output and motor three-phase connection.

3. Laminated composite busbar: Alternating lamination of copper and insulation film, low parasitic inductance, specially for inverter interior.

✅ Development Trend

Vehicles are upgrading toward 800V and 1000V high-voltage platforms with continuously rising fast-charging current. The proportion of oxygen-free copper busbars keeps increasing. Meanwhile, in integrated electric drive and CTC battery integration solutions, copper busbars become more compact and integrated.