Pin-plate micro assembly by integrating micro-EDM and Nd-YAG laser

This paper presents a novel technology that applies the principle of Molten-Separation Joint (MSJ) from the micro-part back to perform precise micro assembly. This has been realized by using a hybrid process that integrates micro-EDM and Nd-YAG laser welding on a single machine to fabricate micro parts and complete precise micro assembly. To demonstrate this novel technology, we used this hybrid process to assemble a product, which is referred as a pin-plate. It consists of a micro pin with down to 50 mum in diameter jointed to a thin plate with 200 mum thick, and is made of SUS304. A tensile mechanism has been designed to measure the strength of the pin-plate after micro assembly. The results on SUS304 show that the joint strength is higher than that of the substrate for a micro pin with 200 mum in diameter. In addition, the pin-plate perpendicularity can be measured with a micro probe and a short sense discharge circuit specially installed in the micro-EDM. The detected results were quite satisfactory. This was further assured by observing the assembled joint cross section through a microscope. (C) 2002 Elsevier Science Ltd. All rights reserved.