A highly reliable design for a nonmetallurgical contact-joint structure consisting of an adhesive film

The interconnection reliability of a contact-joint structure with anisotropic conductive film (ACF) or non-conductive film (NCF) was evaluated in terms of stability of the compressive force at the contact face between a chip bump and a substrate pad. The key factor that dominates the interconnection reliability during temperature cycling is the amount of plastic strain in the chip bump (gold bump) at the contact face. The plastic deformation of the chip bump must therefore be controlled by selecting the appropriate mechanical properties of the adhesive film (ACF or NCF) and the build-up substrate material. Moreover, the interconnection reliability during moisture-resistance tests deteriorates because of stress relaxation near the glass-transition temperature of the commonly used build-up material. It is therefore concluded that a new material system, which includes the mechanical property of the build-up material for preventing stress relaxation, should be developed.