光ディスク基板の射出成形における転写特性の研究

抄録

In the injection molding of an optical disk, a precise minute pit pattern is transcribed from a nickel sheet stamper in 0.3mm thickness. Various defects or mis-transcriptions are sometimes generated, but the causes of these defects have not yet been completely clarified. Thus ideal molding conditions and optimum mold designs can not be precisely determined.
In this paper, the injection molding of an optical disk for a sample-servo-type application is performed by using an injection-compression molding system and the generation mechanism of transcription defects was studied. The following conclusions were obtained.: (1) Mis-transcriptions are classified into three types; multiple transcription errors, scratches in radial directions and scratches in other direction. Their occurrence is affected by the compression pressure holding time and mold temperature. (2) In the case of rather low mold temperatures, multiple transcription errors occur when the compression time is short, but scratches occur when the compression holding time is long. (3) A relative displacement of the polymer molding from the stamper cccurs when a cooling time is longer than 10s, which results in multiple transcription error.