Micro-wire joining design setup and testing
Date of Issue2014
School of Mechanical and Aerospace Engineering
Wire sawing technology is one of the Free Abrasive Machining (FAM) techniques in order to cut very thin wafers from large diameter ingots of crystalline semiconductor material (Silicon) used in semi-conductor industry for the production of solar cells. The process has many advantages i.e. it can produce wafers with high surface finish and minimum kerf loss. The use of thinner wires is to produce more wafers out of a silicon ingot. The wire used must sustain high tension during the course of the cutting processes. Carbon - Steel wires are the most widely used in wafer cutting process due to the high strength and are commercially available in abundance in the market. Diamond particles are added to the Carbon- Steel wires in order to increase the cutting efficiency. The wires once used cannot be used a second time, so it has to saw as much as silicon in the first cut. Closed loop wires are required in many applications such as wire-sawing. Wire sawing uses wires that are as small as 140 micrometres in diameter. While open loop wires are easily available commercially, closed loop wires are restricted to a few manufacturers. For local wire sawing experiments it is important to design and develop a system to join the micro-wire ends using welding techniques so that the wire withstands the forces during the cutting operation. There are a lot of welding techniques available; one such method is the laser welding. Due to the inherent property of the laser it provides a greater control over the wire joining process of very small ends and the optimal tension during wafer sawing process was achieved.