The residual stresses in an epoxy film coated on Si wafer induced during polymerization at room temperature are investigated. The curvature measurement method and the boundary element method (BEM) are employed to investigate the residual stresses. An epoxy film is coated on a relatively thick Si wafer. The normal stress across thickness of the epoxy film is estimated from wafer curvature measurements to be 15- 20MPa . The boundary element method is employed to investigate the whole stresses in the film. The numerical result for the normal stress across thickness of the film, σ xx , shows good agreement with the experimental result obtained by using the curvature measurement method. The singular stress is observed near the interface corner. Such residual stresses are large enough to initiate interface delamination to relieve the residual stresses.