JPH05291418

PURPOSE:To form a display mark which is mainly a letter and a number by using a pattern which leaves the pattern plane of the letter, etc., as a flat plane and the periphery of the letter, etc., as a rough plane. CONSTITUTION:A laser mask 1 is formed of a transparent part composed of a glass board, etc., and an opaque part (laser beam shielding part) 2 is formed of a metal film composed of chromium, etc., using a pattern for a display mark. Laser beams 3 are applied from a laser source 4. The resin compact 5 of a semiconductor package has a lead on the side plane. A laser mask 1 is set between the laser source 4 and the package 5 and the surface of the package is irradiated with the laser beams 3. The laser beams 3 only passes through the transparent part of the mask 1, burns the mirror surface or the smooth surface of the package and a roughened surface 6 is formed. A smooth surface part 7 which is not roughed is left as a letter pattern.