Thermal Stress in Multilayered Flexible Solar Cell Circuit With Different Temperatures

ABSTRACT Under space‐relevant wide‐temperature conditions, multilayer flexible thin‐film GaAs solar‐cell circuit assemblies can develop warpage and thermal stresses due to thermo‐mechanical mismatch among constituent materials. This study combines temperature‐dependent experimental characterization with finite element simulations to investigate the assembly‐level thermo‐mechanical response. Tensile tests and stress‐relaxation experiments were conducted at different temperatures to obtain elastic properties of key materials and the viscoelastic response of polyimide (PI) films, and these data were used to build a thermo‐mechanically coupled finite element model of the multilayer circuit structure. The simulations show a temperature‐dependent change in warpage direction. Intra‐layer thermal stresses redistribute with temperature, where the copper layer exhibits the highest stress level at low temperatures and the cell layer exhibits the highest stress level at high temperatures. This stress‐bearing shift is associated with the temperature dependence of material properties and constraint‐controlled load sharing, and is also influenced by the discontinuous load path introduced by the discrete cell‐array geometry. In addition, peeling‐ and shear‐related indicators were extracted and compared along critical interfaces as a screening‐level assessment of interfacial damage under thermal loading. The results provide theoretical support to the analysis of temperature‐dependent stress evolution and reliability assessment under wide‐temperature thermal loading.