Thermal fatigue life evaluation of epoxy resin/Si joint under mineral oil condition

Thermal fatigue life of epoxy resin/Si joint under mineral oil condition including impurities was evaluated by diffusion-structure coupled FEM analysis. The mass of the mineral oil impurities in epoxy resin increases with an increase in the number of thermal cycles by the diffusion phenomenon. An increase in the mass of the impurities in the resin causes swelling, which increases the stress intensity factor range ΔK_i at the joint interface. ΔK_i under the mineral oil condition increases by 1.5 times compared to that under air atmosphere. Swelling significantly shortened the thermal fatigue life under the mineral oil condition. Thus, swelling by diffusion of mineral oil impurities into epoxy resin becomes a dominant factor over thermal fatigue life of the joint.