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Original Technical Problem
How To Balance package integration and thermal durability in Battery Disconnect Units
Technical Problem Background
The challenge involves resolving the inherent conflict in Battery Disconnect Units (BDUs)—where increased integration (reduced size, fewer parts, tighter component spacing) exacerbates thermal stress on insulating materials and electromechanical components during normal and fault conditions. The solution must enable compact, manufacturable packaging while ensuring thermal durability under repeated thermal cycling (-40°C to +125°C) and short-duration high-heat events (e.g., fuse activation at >180°C), all within automotive safety and cost constraints.
| Technical Problem | Problem Direction | Innovation Cases |
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| The challenge involves resolving the inherent conflict in Battery Disconnect Units (BDUs)—where increased integration (reduced size, fewer parts, tighter component spacing) exacerbates thermal stress on insulating materials and electromechanical components during normal and fault conditions. The solution must enable compact, manufacturable packaging while ensuring thermal durability under repeated thermal cycling (-40°C to +125°C) and short-duration high-heat events (e.g., fuse activation at >180°C), all within automotive safety and cost constraints. |
Transform the BDU housing from a passive structural component into an active thermal management system via multi-material co-molding.
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InnovationBiomimetic Multi-Material Co-Molded BDU Housing with Embedded Thermal Superhighways
Core Contradiction[Core Contradiction] Increasing package integration (compact size, minimal parts) reduces thermal durability due to heat accumulation during high-current fault events.
SolutionLeveraging TRIZ Principle #24 (Intermediary) and first-principles heat transfer, the BDU housing is co-molded via two-shot injection using a structural base of glass-fiber-reinforced PPS (CTI >600V) and embedded thermal superhighways of vertically aligned graphite-filled LCP (thermal conductivity ≥30 W/m·K along flow direction). Inspired by leaf venation, these superhighways form direct conduction paths from hotspots (fuses/relays) to external cooling interfaces. The co-molding process uses sequential melt temperatures (PPS: 310°C, LCP: 290°C) and mold surface temp control (80–100°C) to ensure interfacial adhesion (>8 MPa shear strength). Validation targets: internal temps 5 kV/mm). Materials are commercially available (e.g., Celanese Vectra E130G30, Solvay Ryton R-4-200BL).
Current SolutionMulti-Material Co-Molded BDU Housing with Integrated Thermally Conductive Pathways
Core Contradiction[Core Contradiction] Increasing package integration (compact size, minimal parts) reduces thermal durability due to heat accumulation during high-current fault events.
SolutionThis solution transforms the BDU housing into an active thermal management system via multi-material co-molding: a structural base layer of amorphous polycarbonate (PC) with 24–35% talc (TC ≈ 1.0 W/m·K) is overmolded with localized zones of PC/graphite composite (60–68% PC + 32–40% graphite, TC ≈ 16 W/m·K). The high-conductivity zones align with fuse and relay hotspots, forming direct thermal pathways to external cooling interfaces. Process parameters: first-shot melt temp 310°C, mold temp 80°C; second-shot melt temp 300°C, mold temp 90°C (Sumitomo SE 180DU-C450). Quality control: steady-state hotspot temperature ≤142°C during 200°C fault simulation (5W resistor test per IEC 60068-2), housing flatness tolerance ±0.1 mm, interlayer adhesion pass 0.75m drop test without delamination. Achieves 27% volume reduction vs. baseline while maintaining UL94 V-0 flammability rating and -40°C to 150°C operational stability.
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Resolve functional conflict by assigning dual roles (electrical + thermal) to primary conductors.
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InnovationDual-Function Monolithic Busbar with Embedded Thermal Shunting and Selective Dielectric Coating
Core Contradiction[Core Contradiction] Assigning dual electrical conduction and active thermal management roles to primary conductors in BDUs without increasing part count or compromising insulation integrity under thermal shock and fault heating.
SolutionThis solution integrates monolithic copper-aluminum hybrid busbars where the aluminum core carries bulk current (reducing weight/cost), while a thin, continuous copper skin ensures low contact resistance and serves as a high-conductivity thermal shunt. The busbar is selectively coated via electrostatic fluidized bed powder coating (0.2–0.4 mm thick) with a thermally conductive dielectric (e.g., Resicoat® EL4, k > 1.5 W/m·K, dielectric strength >3500 V/mm), leaving only terminal zones uncoated. During operation, heat from Joule losses and fault events conducts radially through the copper skin into the dielectric layer, then dissipates directly to an adjacent aluminum housing acting as a heat spreader—decoupling thermal pathways from signal components. Process parameters: coating at 180–200°C curing temp, conveyor speed 0.5 m/min; quality control via IR thermography (ΔT < 8°C across busbar at 500 A) and hipot testing (2.5 kV AC, 1 sec). Validated via multiphysics FEM simulation; prototype validation pending—next step: thermal cycling (-40°C ↔ +150°C, 1000 cycles) per ISO 16750-4.
Current SolutionU-Shaped Dual-Role Busbar with Integrated Heat Dissipation for Compact BDUs
Core Contradiction[Core Contradiction] Assigning dual electrical conduction and thermal dissipation roles to primary conductors in Battery Disconnect Units (BDUs) to enable high package integration without compromising thermal durability under fault-induced heating and thermal cycling.
SolutionThis solution integrates a U-shaped heat dissipation element directly onto the BDU busbar enclosure, where the base contacts the enclosure and side/intermediate wings extend outward for convective cooling. The primary copper or Al-Cu hybrid busbar conductors serve dual roles: conducting high current (up to 1000 A) and transferring Joule heat through the enclosure to the U-shaped dissipator. Clamping bolts double as mechanical fasteners and thermal interface enhancers, applying uniform pressure (5–8 N·m torque) to ensure low thermal contact resistance (3500 V/mm). Materials: Cu-Al hybrid conductors, extruded aluminum dissipators, PPS+30% glass fiber housing. Assembly uses modular snap-fit stacking with automated torque-controlled clamping.
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Use material zoning and geometric segmentation to isolate thermal domains without increasing external envelope size.
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InnovationThermally Zoned, Segmented BDU with Functionally Graded Ceramic-Polymer Composite Housing
Core Contradiction[Core Contradiction] Increasing package integration in BDUs reduces thermal durability due to heat accumulation and material degradation under high-temperature cycling and fault-induced heating.
SolutionWe propose a material-zoned, geometrically segmented BDU housing using a functionally graded composite: inner high-thermal-conductivity zones (AlN-filled PPS, k ≈ 8 W/m·K) adjacent to power components for heat spreading, and outer low-conductivity zones (hollow microsphere-reinforced PEEK, k ≈ 0.2 W/m·K) for thermal isolation. Geometric segmentation creates thermally independent cavities via laser-cut kerf gaps (50–100 µm wide) filled with aerogel, decoupling relay/fuse thermal domains without enlarging the envelope. The housing is co-molded in a single step using insert molding with embedded busbars. Validation target: 15 MPa at material interfaces. Materials are commercially available; process uses standard automotive injection molding with ±0.05 mm dimensional tolerance.
Current SolutionSegmented Multi-Material Thermal Zoning in BDU Housing for Compact High-Durability Integration
Core Contradiction[Core Contradiction] Increasing package integration (reducing size and part count) intensifies thermal crosstalk and material degradation, compromising long-term thermal durability under high-temperature cycling and fault-induced heating.
SolutionAdopt a segmented thermal zoning architecture inspired by Corning’s segmented thermal barriers (Ref. 4), where the BDU housing integrates geometrically separated modules—each with tailored material properties—within a fixed envelope. High-heat zones (e.g., near pyro-fuses) use aluminum-nitride-filled PPS (thermal conductivity: 5–8 W/m·K), while sensitive relay zones employ low-conductivity (125°C), maintaining isolation without adhesives. The design achieves 3 kV AC). This approach reduces volume by 22% vs. conventional BDUs while enabling field-replaceable modules.
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