Copper pillar tin bump (CPTB) was developed for high density chip interconnect technology. Copper pillar tin bumps that have 100μm pitch were introduced with fabrication process using a KM-1250 dry film photoresist (DFR), copper electroplating method and Sn electro-less plating method. Mechanical shear strength measurements were introduced to characterize the bonding process as a function of thermo-compression. Shear strength has maximum value with 330℃ and 500 N thermo-compression process. Through the simulation work, it was proved that when the copper pillar tin bump decreased in its size, it was largely affected by the copper oxidation.