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68 SMT007 MAGAZINE I JUNE 2026 EV reliability is often discussed at the vehicle or system level, but many of the most persistent failures begin at the materials level. Semiconductor devices, ceramic substrates, die at- tach materials, wire bonds, clips, thermal interface materials, laminates, coatings, seals, and coolants define the electrical, thermal, and mechanical limits of the hardware. Once EV architectures move toward higher volt- ages, switching speeds, and power density, and longer service life, those materials are pushed harder, and small weaknesses can turn into large field problems. Wide-bandgap devices can raise efficiency and reduce mass, but they also place more stress on gate oxides, passivation, intercon- nects, insulation systems, and cooling paths. 1,2,3 This matters because materials failures rarely stay local. A single degraded interface can raise thermal resistance, increase current crowding, alter switching behavior, damage neighboring parts, and shorten the life of the assembly. In the field, the result may appear as reduced range, charging interruption, inverter shutdown, isolation fault warnings, intermittent behavior, derating, or complete module failure. Current crowding occurs when electrical current does not flow uniformly through a conductor, but instead concentrates in localized regions such as edges, corners, contact THE FOUNDATIONAL TECHNOLOGIES OF MATERIALS in EV Reliability ROA D TO R E L I A B I L I T Y BY STA N TO N R A K , S F R A K C O M PA N Y Figure 1: Examples of materials comprising a power module (Semikron-Danfoss). 4