| 摘要 |
PURPOSE: To make a lapping surface difficult to wear out or deform plastically and to maintain good flatness of the lapping surface in a surface plate for polishing, which is used for lapping work on a silicon wafer, by specifying the strength of the material for a main body. CONSTITUTION: A main body 2 of a surface plate 1 for polishing is a doughnut- shaped flat board having a circular hole 3 at its center, while grooves 5, in which abrasive grains run, are formed in a latticed form on the side of a lapping (abrasive) surface 4, which faces a work piece, of the plate 1. In manufacturing the surface plate 1 for polishing like this, casting is made first, using nodular graphite cast iron and a 'furan' mold. Next, this casting is held, for instance, at 950 deg.C for eight hours and then put into an oil bath for quench-hardening. After this, the casting is tempered at 550 deg.C for three hours, so that a base (parent) material becomes temper martensite. With this, the strength at the 0.2% elongation of the main body 2 becomes 50kg/mm<2> or more, while both flatness maintaining performance and life-time of use of the plate 1 can be enhanced. |
