The mechanical and thermal responses of encapsulated flip chip solder bumps on a surface laminar circuit (SLC) board have been determined in this study. The mechanical responses of the solder bumps and encapsulant have been obtained by shear, tension and torsion tests. The thermal stress and strain in the solder bumps and encapsulant have been determined by a non‐linear finite element method and the thermal fatigue life of the corner solder bump is then estimated based on the calculated plastic strains, Coffin‐Manson law and isothermal fatigue data of solders. Also, an assembly process of the test boards is presented.