Anisotropic conductive film (ACF) is commonly used as underfill for flip chip assembly. The present study focuses on elastic recovery and stress distribution along the interfaces of particle-pads and underfill-pads associated with heat or a mechanical loading. In the same manner as the experimental process for ACF assemblies, ACF interconnection is simulated using FEM. Firstly, the properties of the nickel were determined by fitting FEM to the experimental results. After that, the nickel properties are used for ACF interconnection analysis. We found that delamination may also occur at a three-joint interface of a particle, a pad and an underfill at the lowest temperature during a heat cycle.