Copper pillar tin bump (CPTB) was developed for high density chip interconnect technology. Copper pillar tin bumps that have $100{mu}m$ 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 $330^{circ}C$ and 500 N thenno-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.