PURPOSE: To eliminate magnetization and residual strain during welding, and to improve mechanical filter characteristics, by heating an electromechanical transducer, a resonator, and a coupler at specific temperature after electric welding.
CONSTITUTION: Copper-made electrodes 5 and 6 are placed on and under electromachanical transducers 1, a coupler 3, and resonators 2 and while the electrodes are depressed, a large current is applied. Then, resistive heat generation is caused at contacting parts of the electrodes 5 and 6 to weld the contacting parts of both the metals. At this time, the transducers 1, coupler 3, and resonators 2 are magnetized because they consist essentially of constantly elastic metals, causing residual magnetization. To reduce this residual magnetization and mechanical residual strain, a heat treatment is performed at sufficient temperatures (100∼200°C) and then the temperature is lowered gradually. Consequently, mechanical sharpness and a decrease in Q is prevented.
KASAI YOSHIHIKO
KATSUBE YOSHIO
