Laser microjoining of dissimilar materials

Transmission laser bonding (TLB) is used to join dissimilar materials in implant devices because of its many advantageous features over the conventional joining techniques, in addition to its essential biocompatible property. Although some experimental works are reported in the literature, TLB is not studied well. We have investigated the mechanism of TLB joining process of dissimilar materials by finite element analysis. The effect of process parameters such beam scanning speed, the power and the diameter of the laser beam studied to optimize transmission bond for both diode laser and fiber laser. Finite element model simulation provides quick and reliable way to study the effect of process parameters to ensure optimized bonding conditions. The quality of the bond is characterized by the strength of bond which is measured by microtester for lap joint using rectangular samples. Bond performance in normal environment and bio environment were determined. An alternative technique for bond evaluation using pressure testing has been developed using miniaturized samples.;The experimental data and numerical analysis shows no bonding is possible at 1W power for fiber laser. At higher power level the bonding is possible. But this depends on scanning speed of the laser beam. If the scanning velocity is too slow, the joining substrates get heated significantly such that molten substrate can vaporize to some extent resulting in a weak or no bonding condition. Again too fast scanning of the laser beam does not provide enough heat energy to the joining substrate to melt and form a bond to the adjacent layer.