FRONTIERS FOR ENGINEERING MATERIALS

The ability of high-power lasers to deliver controlled amounts of energy, in a focused spot size ranging from 1 mu m (excimer laser) to 10 mu m (Nd:YAG laser) to 200 mu m (CO2 laser), has led to many applications of such lasers in electronic assembly. Initial studies concentrated on laser soldering when the reduction in size and increased complexity of integrated circuits in electronic assembly made it more difficult to obtain reliable joints by conventional techniques. Although laser soldering has not yet been widely implemented (except for specialised components), lasers have found application in the meantime in many other areas of electronic assembly. For optimum performance in all of these applications, the laser parameters - wavelength, pulse duration, beam power density - must be matched with the thermophysical characteristics of the target materials. We will provide a brief review of these applications, describe research work in progress in our laboratory in one of these areas, and indicate the likely directions of future applications.