Asahi Glass Company, Limited

John Hsieh

Andrew M Homola

David Vigdor Salamon

Holland Hodges

Christopher H Bajorek

Robert M Tierney

A method for forming a magnetic disk comprises the following steps. First, an inner and outer cut is provided in a work piece. The waste piece thus comprises an outer waste piece, an inner waste piece, and a region between the inner and outer waste pieces that is to be used as a substrate for manufacturing a magnetic disk. The outer waste piece is separated from the substrate by applying a hot plate against the outer waste piece, thereby causing it to thermally expand and separate from the substrate. The substrate is then placed over (but not in contact with) a hot plate, while a cooling element is placed on the inner waste piece. This causes the substrate to thermally expand while the inner waste piece thermally contracts. Thus, a gap forms between the substrate and inner waste piece, thereby permitting the separation of the inner waste piece from the substrate.

Removal of enclosed glass parts after cutting using heating and cooling techniques

A method for manufacturing a substrate for a magnetic disk comprises the acts of mounting a workpiece on a spindle; rotating the workpiece and scribing the workpiece to form first and second scribe lines on the top surface of the workpiece and first and second scribe lines on the bottom surface of the workpiece; and breaking the workpiece along the first and second scribe lines. The first scribe line on the top and bottom surface of the work piece defines the outer diameter of the substrate. The second scribe line on the top and bottom surface of the workpiece define the inner diameter of the substrate. Because scribe lines are formed on the top and bottom surfaces of the workpiece, the edge of the substrate is less jagged than substrates that are merely scribed on one side of the workpiece and then broken. Because the scribe lines are formed by mounting the workpiece on a spindle and rotating the substrate, the scribing can be done more precisely and quickly than scribe lines formed using an x-y platform.

Method for manufacturing a substantially circular substrate by utilizing scribing

A method for manufacturing a magnetic disk comprises the step of applying a continuous laser beam to both sides of a glass workpiece and etching both sides of the workpiece with an aqueous acidic fluoride-containing etching solution. The portion of the workpiece receiving the laser beam etches at a much faster rate than the portions of the workpiece that were not exposed to the laser beam. The workpiece is then broken along a line or curve formed by the above-mentioned steps. The resulting structure is a substrate used to form a magnetic disk. The disk is completed by depositing an underlayer, a magnetic layer and a protective overcoat on the substrate.

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John Hsieh