Sealing for E-Drive Copper Busbar Connectors in NEVs：Why All Traditional Solutions Failed — and How Elaplus Flexible Epoxy EP 1721-1 Succeeded
I. Industry Background: Why Copper Busbar Connector Sealing Became an “Impossible Trinity” Driven by the integration trend of “multi-in-one” electric drive systems in new energy vehicles (NEVs), the reducer, motor, and electronic control units share a common housing. This compact structure leaves minimal room for sealing design. More critically, gear oil (e.g., BOT805) inside the reducer coexists with high-voltage electrical systems — seal failure can lead to minor issues like grease-contaminated electrical connections, or major hazards such as short circuits. As the core node for three-phase power transmission, copper busbar connector sealing must simultaneously meet three conflicting requirements — the “Impossible Trinity”: 1.Flexibility: Resist cracking under thermal cycling from -40°C to +155°C 2. Oil Resistance: No swelling or softening under long-term gear oil immersion 3.Adhesion: Reliably bond to both PPS plastic and copper metal heterogeneous interfaces II. Why All Traditional Solutions Failed Before EP 1721-1, the industry relied on four main types of sealing materials, each with fundamental flaws: Material Type Flexibility Oil Resistance High-Temp (150°C) Heterogeneous Adhesion Overall Verdict Rigid Epoxy ✗ High modulus ✓ Solvent-resistant ✓ Good heat resistance ✓ Good metal adhesion Cracks inevitably during thermal cycling Silicone ✓ Flexible F80000 ✓ Wide temperature range ✗ Weak adhesion Eroded by oil Polyurethane (PU) ✓ Flexible ✗ Hydrolysis/oil degradation ✗ Insufficient heat resistance ✓ Good adhesion Fails at high temperatures Acrylic ✓ Flexible ✗ Solvent-sensitive ✗ Low Tg ✓ Good adhesion Poor long-term durability EP 1721-1 ✓✓ ✓✓ ✓✓ ✓✓ ✓✓ Meets all requirements comprehensively The core contradiction: In traditional material systems, flexibility and oil resistance are inversely related — the softer the resin, the looser its molecular chains, making it easier for oil molecules to penetrate. This fundamental law of materials science was the insurmountable barrier for all conventional solutions. III. Three Core Technological Breakthroughs of EP 1721-1…
