Patent ID: 8268182

Claim:
A laser processing method for forming a through-hole in a workpiece by means of a pulsed laser beam, the method comprising steps of: providing a removable sacrifice layer on said workpiece; forming the through-hole in said workpiece and said sacrifice layer by the laser beam in a state where said sacrifice layer is provided, the laser beam being applied to said workpiece through said sacrifice layer; and removing said sacrifice layer from said workpiece after said step of forming the through-hole, wherein: an ablation threshold value of said sacrifice layer is not less than an ablation threshold value of said workpiece, the through-hole has a taper angle θ (°)=arctan {(0.5 Da−0.5 Db)/d}, where Da (μm) and Db (μm) respectively represent a diameter of front and rear openings of the through-hole, and d (μm) represents a thickness of said workpiece, and (θ×d 0.68 )/φ≦4.0 is satisfied where φ (μm) denotes a diameter of said laser beam.