Toshiyuki Amimoto

Quantitative estimation of conditions for solid-state bonding of Cu

This paper describes the conditions, especially for bonding time and temperature. Assuming that bonding of Cu depends on its recrystallization, the process can be estimated as follows. First, the temperature change of bonding parts is calculated by a simulation using F1-M. Conditions for the upper energy limit are given so the temperature does not exceed melting point. Then using Krupkowskis formula for recrystallization growth rate, constants are sought 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. Conditions for lower energy limits are given as 90% of recrystallization rate. This hypothesis is verified by the fact that the conditions derived from the above calculation are in good agreement with the conditions of the experiment bonding Cu wires to Cu lands of printed circuit boards by parallel gap bonding, . As a result, it is now possible to choose a suitable bonding method and the conditions, not relying on experience OF trial and error.