To lessen the consumption of electric power by precluding the laser irradiation of a high density energy from being needed, reducing the number of lasers, and simplifying the device.
The plate material 50 is formed with a laser beam absorption layer 52 consisting of carbon black or the like with a high coefficient of light absorption on the surface of a film foundation material 51 of a thickness of about 100μm made up of PET, on the surface of which, a decomposed foam resin layer 5 consisting of a diazo group is formed, and a silicone resin layer 54 of a thickness of about 1μm is formed thereon, and further a base film 55 for permeating laser beams is close-adhered on the surface. When irradiating the plate material 50 with laser beams, the decomposed foam resin layer 53 is heated to produce a nitrogen gas with the result that the silicone resin layer 54 is given an expansion distortion through its pressure. After that, when separating the base film 55, the expansion part is separated together therewith producing a recess to thereby form a flat recessed plate. The laser beams are available by an energy ranked lower at one grade than conventional one, so that the number of lasers can be reduced and thus the device can be simplified.
AOKI MASAKAZU
ISONO HITOSHI
