QUANTITATIVE ESTIMATION OF CONDITIONS FOR SOLID-STATE BONDING OF CU

This paper describes the solid-state bonding conditions of Cu, with em phasis on bonding time and temperature. Assuming that the bonding of C u depends on its recrystallization, the process can be predicted as fo llows. First, the temperature change of the bonding parts is calculate d by a simulation using FEM. Conditions for the upper energy limit are given in order that the temperature does not exceed the melting point . Then; using Kruptowski's formula for the recrystallization growth ra te, constants are determined by the measurement of isothermal changes. From the formula and temperature change, the recrystallization change is calculated as-the accumulation of growth in a short time. The lowe r energy limit is taken as 90% of the recrystallization rate. This hyp othesis is verified by finding that the conditions derived from the ab ove calculation are in good agreement with the conditions of an experi ment concerning the bonding of Cu wires to Cu lands of printed circuit boards by parallel gap bonding. As a result, it is now possible to ch oose a suitable bonding method and conditions without relying on exper ience or trial and error.