1986 Volume 4 Issue 1 Pages 40-46
Dissimilar joints of nonferrous metals like as contacts of micro switchgears are required high quality and non-deformation at bonds.
For this purpose, vapor-shielded pressure bonding process and in-process control system applicable to the process are developed.
For the control of material deformation, heating characteristics and temperature distribution while bonding are examined by computer simulation as the first step for the development of the above process.
Then, the optimum electrode materials and their constitution are estimated for the joint couple of Ag and Cu.
Results obtained are summarized as follows.
(1) Electrodes Mo-Mo (φ4 mm) can rapidly heat the joint to the bonding temperature under the condition of comparatively low current density. But, these electrodes cause extreme deformation of Ag and unstable heating characteristics.
(2) Comparing with small diameter (φ4 mm) of electrodes, large one (φ10 mm) can improve the Ag deformation and the stability of heating. However, neither grade of deformation nor bonding stability are allowable for practical use.
(3) Over-excess of deformation at high current region contracts the allowance of practical bonding condition.
(4) Computer simulation can be applied to estimate the heating characteristics by considering contact resistance from the experimental results.
(a) Electrodes Mo-Mo give relatively flat temperature distribution in the joint materials.
(b) Electrodes CuCr-CuCr, which can heat the joint to the bonding temperature by high current condition, can give the peak temperatre at the bonding interface. So, bonding can be achieved under lower average temperature in the whole joint than with electrodes Mo-Mo.
(c) Arrangement of each electrode such as CuCr to Ag side and Mo to Cu side can achieve bonding under relatively low current condition and low average temperature in Ag material.