Dr.ing. Sorin Savu

 

Abstract

The low electrical resistance and the high mechanical resistance of the wires used to make the electrical micro-contacts represent the requiered characteristics for the parts of the industrial electronic devices.
The paper proposes a new method for joining and micro-joining the electrical wires using the microwave plasma, as thermal source, in controlled or free vacuum. For microwave  plasma generation it is used a microwave generator and a mono-mode heating chamber. For the experiments, the copper wires of 0.5 mm in diameter were used in order to manufacture the pins from electrical contacts. For plasma arc initiation have been used the cylindrical electrodes made from barium ferrite, type W of 20 mm in diameter and 4; 6 and 8 mm in height. The microwave generator used in the experiments was a classic generator with adjustable power up to 1250 W. The paper presents the conditions for initiation and stabilization of the microwave plasma for a low power injected in the ferrite electrodes and it makes an analysis of the microwave heating process mechanism for the obtaining the microwave plasma. The characteristic followed during the experiments was the electrical resistance of the joints. Thus, before the joining process, the electrical resistance of each sample has been determined. The both values have been used to appreciate the influence of the joining process on the electrical behavior of the joint, and finally it was made a comparative study between the electrical resistance of the joint and the electrical resistances of the joints for similar samples obtained by laser welding, micro-TIG, plasma arc welding and soldering.