Laser processing methods

Abstract

This invention provides a technique for maintaining or improving processing quality even when drilling multiple holes with a narrow spacing. The laser processing method includes: a step of forming a protective sheet on the front side of a substrate (S1); a step of setting a first drilling position group and a second drilling position group to a second spacing, which is a spacing greater than or equal to the processing hole diameter of the protective sheet, when the first spacing between multiple drilling positions on the front side of the substrate is smaller than the spacing between the holes of the protective sheet (S0); a step of performing a first drilling process and forming a first hole by irradiating the first drilling position group with a laser (S2); a step of forming a new protective sheet (S3); a step of performing a second drilling process and forming a second hole by irradiating the second drilling position group with a laser (S4); and a step of removing the protective sheet (S5).

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