Method of forming striped pattern of thin film material on board and masking apparatus used in the method

摘要

As a method of manufacturing an optical low pass filter by evaporating thin film material on the surface of a board to form striped pattern of thin film material having mountains and valleys formed at a fixed pitch on the surface of the board, a method of arranging wire on the surface of the board at the fixed pitch and evaporating thin film material while using the wire used as a mask. However, in this method, it is difficult to put the wire on the surface of the board at the accurate pitch with the wire stretched on the board. In a masking apparatus of the present invention, grooved rods (12a) and (12b) including V-grooves (15a) having V-shaped section and formed at an equal pitch are fixed on both sides of holding members (10). A tension exerting member (21) for exerting resilient force on wire (L) is disposed above a surface opposite to a surface of the holding base (11) on which the board is held. The tension exerting member (21) is disposed in a place different from place of the holding members (10) in which the grooved rods (12a) and (12b) are fixed on so as not to exert the tension on the grooved rods (12a) and (12b). The wire (L) passes on the tension exerting member (21) to be suspended between the grooved rods (12a) and (12b) and is wound on the holding members (10) spirally. The wire (L) is wound exactly in the V-grooves (15a) of the grooved rods (12a) and (12b). Furthermore, when the tension is exerted on the wound wire (L) by the tension exerting member (21), the grooved rods (12a) and (12b) are not moved and accordingly the V-grooves (15a) are not moved from the original positions thereof. Accordingly, the wound wire (L) is put on the surface of the board (1) at the accurate pitch tautly while the wound wire (L) is held in the V-grooves (15a) exactly. <IMAGE>