Effects of Thermal acid generator and Sn58Bi solder addition on the electrical properties of Cu/epoxy paste

Abstract

Multilayer ceramic capacitor (MLCC) has been widely used in various electronic devices such as personal computer, cell phone, and other electrical products for storing energy, filtering signals, and electric circuit protection. Epoxy pastes can be used as interconnection between MLCC and electrodes. Conventionally, good elec-trical conductive metal powders such as gold, silver, and their alloys have been used as fillers in paste. These metals have good electrical conductive and thermal conductive properties. However they are expensive. Nowa-days, Copper powders have been used as fillers for conductive paste because of their lower price, good electrical conductivity, and good thermal conductivity. When using Copper powders as conductive fillers, the issue is the electrical conductivity of Cu/epoxy paste. Cu/epoxy paste provides electrical path between electrodes through physical contacts between Cu pow-ders. However, Copper oxide disturbs the electrical flow. In this research, in order to increase the electrical prop-erties of Cu/epoxy paste, Thermal acid generator (TAG) and Sn58Bi solder powders were added into the Cu/epoxy paste. TAG materials generate acid to remove native oxides of copper powders and Sn58Bi powders. Copper powders and Sn58Bi solder powders melted and Cu-Cu network, Cu-Sn58Bi network were made during the Cu/Sn58Bi/TAG/epoxy paste curing process. The formation of these networks improves the electrical con-ductivity of Cu/Sn58Bi/TAG/epoxy paste. In chapter 2, effects of Copper powder size and shape on the sheet resistance of Copper/epoxy paste were studied. As Cu powder contents get higher, the sheet resistance of pastes has tendency to lower. The sheet resistances of pastes decrease using bigger Cu powders. Using mixture of sphere particle and flake particle, the sheet resistances of pastes decreased more. In chapter 3, effects of Thermal acid generator addition on the properties of Copper/epoxy paste and on the properties of epoxy resin w...