| 摘要 |
PURPOSE:To suppress the generation of chipping defects in an obtained board for information recording medium by a method wherein a casting mold, the size of the pre-format projected part of projected and recessed pre-format pattern of which is reduced stepwise toward its tip. CONSTITUTION:At a casting mold of a board for information recording medium having projected and recessed pre-format, the size of the pre-format projected part 2 of projected and recessed pre-format pattern formed on the mold board is reduced stepwise toward its tip. Variations can be produced by utilizing the difference between the etching speeds of laminated projected part forming materials 3 and 3' so as to be able to produce a three-dimensional shape, in which the size of the pre-format patterns made of the respective materials are reduced stepwise in the direction of the thickness or toward the tip on the casting mold, resulting in allowing to reduce the chipping defects of the pre-format of the board. The projected part forming materials having different etching speed are realized by laminating layers of thin film made of metal, dielectric, organic matter and the like. |
