3D-MID and process monitoring for microjoining applications

Abstract

Nd:YAG solid-state lasers have been integrated in many seam welding applications. They provide a good ability of integration into existing manufacturing sequences and allow its easy automation. Appropriate process monitoring systems are needed to decrease necessary user intervention, to ensure a high machine availability and to realize a zero defect production. In the electronics industry, laser spot welding techniques using pulsed Nd:YAG-lasers have been established in mass production applications, for example in manufacturing of electron gun components for TV monitor tubes over the last 25 years. They require different strategies and methods for process monitoring systems. Apart from these integrated laser spot welding applications, there is a current demand for new technologies to join micro components onto 3-dimensional (3-D) circuit substrates and to connect electrical plugs. In recent years, laser spot joining techniques have emerged as a viable option for packaging electrical and mechanical microparts, such as surface mounted devices (SMDs) and casings. Under most conditions, laser spot welding provides more durability as well as thermal and mechanical stability compared to traditional packaging techniques, such as simultaneous soldering. Additionally, under less ideal conditions, the packaging quality can be inconsistent, resulting in the need for optimization and monitoring of the weld parameters under different conditions. In order to achieve a stable process during packaging of electrical components despite their weak absorption of laser radiation and different surface qualities, a process monitoring system should be needed.