Characterization of diamond wire-cutting performance for lifetime estimation and process optimization

Diamond abrasive-coated wire is a tool for the precise multi-wire sawing of mono-crystal ingots to manufacture substrates. This tool is used to cut hard materials such as silicon carbide, gallium nitride, sapphire and silicon. The cutting performance of diamond wires strongly influences the accuracy of substrates in terms of roughness, total thickness variation and BOW. Nonetheless, changes in cutting performance as a result of gradual wear through repeated contact complicate the optimization of diamond wire use. A characterization method is proposed for the cutting performance and lifetime of a diamond wire based on mathematical modeling and experimental results. The theoretical model predicts that cutting accelerates with the application of a strong feed force and small abrasives due to an increase in indentation depth for each abrasive. Experimental results showed that a wire with a low concentration exhibited an increased material removal rate. However, the lifetime of the wire displayed an opposite trend; that of a diamond wire can be classified into two regimes. The first one is an increased loss of abrasives as a result of rapid wear attributed to a low concentration; the second regime is caused by a drop in actual contact pressure due to the enlarged contact area between the workpiece and the bonding material enveloping the abrasives.