Laser drilling system and method for flexible printed circuit board

A method for drilling holes in a flexible printed circuit board, comprising the steps of:

• providing a first mirror and a second mirror spaced apart from each other, the first and second mirrors cooperatively defining a resonator cavity;
• positioning a laser crystal capable of generating a fundamental laser beam, a second harmonic generator, and a third harmonic generator in the resonator cavity;
• directing the fundamental laser beam into the second harmonic generator to produce a second harmonic laser beam;
• directing the second harmonic laser beam and the fundamental laser beam into the third harmonic generator to produce a third harmonic laser beam;
• separating the third harmonic laser beam from the second harmonic laser beam and the fundamental laser beam, and directing the third harmonic laser beam to exit from the resonator cavity as an output laser beam, the output laser beam having the following parameters:
• a wavelength of 355 nm;
• an output power of up to 5 watts;
• an M2 specification of less than 1.2;
• and a pulse width of 50 ns at 10 KHz;
• and
• directing the output laser beam to be incident on the flexible printed circuit board to define the holes therein.

A method for drilling holes in a substrate, comprising the steps of:

• preparing a substrate to be drilled;
• providing a laser generating system capable of drilling said substrate with a narrow-pulse-width, short-wavelength laser generated by said system;
• marking locations corresponding to a plurality of preset holes on said substrate;
• and
• drilling said plurality of holes in said substrate based on said marked locations by means of conducting said laser to said marked locations.