2000 年 66 巻 6 号 p. 912-916
This paper presents the constituent features of the newly developed water-soluble coolant for the multiwire saw slicing of 400mm-diameter silicon ingots. Although the water-soluble coolant has long been awaited for its intrinsic merits over the conventional mineral oil-based coolants, it was not adoptable to the large diameter slicing for its poor ability to suspend abrasives in the slurry. This newly developed coolant is the first successful water-soluble coolant to slice 400mm-diameter ingots, and has the following constituent features; (1) Polypropyleneglycol (PPG) is chosen as a base of the coolant which has no peculiar odor, and has a good bio-degradability. (2) The coolant contains approx. 20wt% of water with chemical affinity to bentonite, and gives non-flammability and non-evaporative characteristics. (3) In order to maintain the viscosity level and the good suspension of abrasives, the coolant contains 3 viscosity adjusting additives; bentonito (thixotropic rheology), cellulose (rheopectic rheology), and synthetic mica (constant viscosity).