Silver-Tin-Silver Coated Resin Particles for Thermal Cycling Adhesion

The silver coating is segmented into multiple layers (first silver layer, tin intermediate layer, second silver layer) instead of a single layer. This segmentation allows each layer to perform specific functions: the first silver layer provides conductivity, the tin intermediate layer prevents peeling and manages thermal stress, and the second silver layer restores conductivity. The multi-layer structure resolves the contradiction by distributing functions across layers, preventing peeling while maintaining electrical conductivity.

A tin intermediate layer is introduced between the resin particle surface and the silver layers. This intermediate layer acts as a mediator that reduces the direct thermal stress between the resin and silver, preventing peeling. The tin layer has thermal expansion properties that bridge the gap between resin and silver, resolving the adhesion problem under thermal stress while allowing silver layers to maintain electrical conductivity.

The total silver coating thickness required for conductivity is segmented into two separate silver layers with a tin intermediate layer in between. This segmentation reduces the continuous thermal stress that would occur in a thick single-layer silver coating. The tin intermediate layer acts as a stress buffer, allowing the silver layers to maintain sufficient thickness for conductivity without creating excessive thermal stress that causes peeling.

The tin intermediate layer serves as a stress-buffering intermediary between the silver layers and the resin particle. It absorbs and distributes thermal stress, preventing the accumulation of stress in the silver layers. This allows the silver layers to be thick enough for good electrical conductivity without suffering from the thermal stress-induced peeling that would occur in a continuous thick silver coating.

The tin intermediate layer acts as a thermal expansion mediator between the resin particle and the silver layers. Tin has thermal expansion properties that are intermediate between resin and silver, creating a gradual transition in thermal expansion coefficients. This reduces the abrupt thermal stress at the resin-silver interface, improving adhesion under thermal cycling. The intermediary layer approach maintains versatility because tin can be combined with various resin and silver configurations without limiting material selection.

The coating structure is designed as a composite material system comprising multiple materials (resin, tin, silver) with complementary properties. The tin intermediate layer provides thermal expansion buffering, while the silver layers provide electrical conductivity. This composite approach resolves the adhesion problem by combining materials with different properties in a functional hierarchy, maintaining adaptability because the composite structure can be applied to various resin and silver material combinations.