Bare die probing with novel anisotropic conductive film (ACF)

Flip chip interconnection technology has been considered the best solution for high-density packaging of a variety of electronic devices. However, there still remain several technical obstacles. The infrastructures are not perfectly ready for die handling/assembling, die-quality assurance, and so on. Especially, an effective bare die testing/screening method is necessary for the electronics industry. The novel Anisotropic Conductive Film (ACF), described in this paper, is composed of high density pillars (linear metal material) which form sequential conductive paths in the direction of the thickness of the thermoplastic film. Developments are ongoing for creating the ultimate IC packaging system for connecting bump-less dice on printed circuit boards, under appropriate thermal pressure conditions. The material and structure of this ACF are optimized for bare die testing/screening applications. The fine pitch terminals, with Au bumps on a bare die, can be probed with reasonable pressure by using this ACF. The electrical contact performance of the ACF was improved in the structure with lower modulus resin, less thickness and optimized pillar pitch. This ACF will hopefully be utilized as an effective interconnecting material for semiconductor device testing/screening systems.