Anisotropic conductive film with a low melting point solder

초록

The conventional ACF (anisotropic conductive film) is composed of polymer based conductive particles coated with a metal layer and the polymer matrix. The electrical conduction is only performed by a mechanical contact of the conductive particles. Sometimes, a short and open circuit due to excessive or inadequate concentrations of conductive particles can hinder the electrical conduction between substrates Therefore, the high current and thermal conduction is basically confined. The chemo-rheological mechanisms of a polymer matrix and a low melting point solder for an anisotropic conductive film (ACF) was characterized. For the material characterization of the polymer matrix and solder, a differential scanning calorimetry (DSC) and a dynamic mechanical analyzer (DMA) experiments were conducted. The conversion and viscosity of the polymer matrix was observed by DSC and DMA, respectively. In order to control the curing conditions such as the reaction temperature and time of polymer matrix, the adequate amount of catalyst was used. The amount of a catalyst was determined by the condition to get a polymer conversion of 0.8 within the total processing time of 5 minutes. The compatibility between the viscosity of a polymer matrix and a melting temperature of solder was characterized to optimize the processing cycle. The reductant was also added to remove the oxide layer performed on the surface of solder in the air environment. The wetting effect of the low melting point solder was experimentally observed with a different amount of the reductant. Based on these chemo-rheological phenomena of the polymer matrix and solder, the optimum polymer system and its processing cycle were designed for the high performance and reliability in the electrical interconnection system.

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