Novel interface regulation of Sn1.0Ag0.5Cu composite solders reinforced with modified ZrO2: Microstructure and mechanical properties

•The concept of Sn/NiO/ZrO2 interface system design is first proposed.•Surface modification of ZrO2 is conducted with ball milling−pyrolysis methods.•The refinement mechanism of microstructure is systematically investigated.•A micro-mechanical lock and non-micropored clean interface is formed.•5.The strength and ductility are simultaneously improved with NiO/ZrO2 addition.