JPH11277279A - Laser processing apparatus and irradiation method by laser processing apparatus - Google Patents

Abstract

(57) [Problem] To reduce a change in laser energy passing through a hole in a mask. SOLUTION: In a laser processing apparatus for performing processing by irradiating a substrate 19 with a pulsed laser beam from a laser oscillator 10 via a fiber 11, a laser beam of the laser beam is placed at a position close to an emission end of the fiber. A uniform optical system 20 for changing the beam mode was provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser processing apparatus for performing processing by irradiating a substrate with a pulsed laser beam from a laser oscillator, and an irradiation method using the laser processing apparatus.

[0002]

2. Description of the Related Art In response to the demand for higher density of printed wiring boards in accordance with the miniaturization and high-density mounting of electronic devices, multilayer printed wiring boards in which a plurality of printed wiring boards are stacked have recently been provided. . In such a multilayer printed wiring board, it is necessary to electrically connect conductive layers (copper foils) between printed wiring boards stacked one above another.

In such a connection, a hole called a via hole reaching a lower conductive layer is formed in an insulating layer (usually a polymer such as polyimide or epoxy resin) of a printed wiring board, and a conductive hole is formed inside the hole. This is achieved by plating. The thickness of the copper foil forming the conductive layer tends to be as thin as 18 μm to 12 μm, and even 9 μm.

Recently, lasers have been used to form such via holes. As shown in FIG. 2, a laser processing apparatus using a laser performs processing by irradiating a pulsed laser beam from a YAG laser oscillator 10 via a fiber 11 to a substrate 19 to be processed.

In the laser oscillator, a pulsed laser beam is generated from the tip of the fiber 11 and the incident lens 1 is generated.
4 to the mask 15. The laser beam formed by the mask is applied to a ceramic substrate as a substrate to be processed 19 via an imaging lens 16 as an imaging optical system.

Note that B in the figure indicates the positional relationship between the beam mode and the mask 15. S2 indicates a use range in the hole of the mask 15.

[0007]

However, when the fiber transmission and the mask imaging optical system are used, the fiber 1
Since the laser beam emitted from 1 is applied to the mask and is imaged on the substrate 19 to be processed, the positional relationship in which the hole of the mask can be set by the beam mode emitted from the fiber 11 is reduced, and the mask The laser energy passing through the hole changes greatly. Therefore, there is a problem that the processing quality of the substrate to be processed 19 changes.

Accordingly, an object of the present invention is to provide a laser processing apparatus capable of reducing a change in laser energy passing through a hole of a mask at each position by using a uniform optical system for a beam mode emitted from a fiber. And an irradiation method using a laser processing apparatus.

[0009]

According to the present invention, there is provided a laser processing apparatus for performing processing by irradiating a substrate with a pulsed laser beam from a laser oscillator through a fiber, the processing being performed in the vicinity of an emitting end of the fiber. The laser processing apparatus is characterized in that a uniform optical system for changing the beam mode of the laser beam and making the intensity distribution of laser energy uniform is provided at the position where the laser beam is to be emitted.

According to the present invention, in a method of irradiating a substrate to be processed by irradiating a pulsed laser beam from a laser oscillator via a fiber to a substrate to be processed, a laser processing apparatus is provided. A uniform optical system 20 for changing a beam mode of a laser beam to uniform the intensity distribution of laser energy at a position, and irradiating the substrate with the laser beam having passed through the uniform optical system. An irradiation method using a laser processing apparatus is obtained.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration of a laser processing apparatus according to the present invention. In FIG. 1, a YAG laser oscillator (hereinafter, referred to as a laser source) is used as a laser source.
A laser oscillator).

Referring to FIG. 1, a laser processing apparatus in one embodiment performs processing by irradiating a substrate 19 with a pulsed laser beam from a laser oscillator 10 via a fiber 11.

A uniform optical system 20 for changing the beam mode of the laser beam and making the intensity distribution of laser energy uniform is provided at a position close to the emission end of the fiber 11. The laser oscillator 10 generates a pulsed laser beam from the tip of the fiber 11 and guides the pulsed laser beam from the uniform optical system 20 to the mask 15 via the lens 14 for incidence. The laser beam formed by the mask 15 is applied to a substrate 19 to be processed via an imaging lens 16 as an imaging optical system.

B in the figure indicates the positional relationship between the beam mode at the tip end of the fiber 11 and the mask 15 as described in the conventional example. S2 indicates a use range in the hole of the mask 15. A in the figure
Shows the positional relationship between the beam mode at the exit end position of the uniform optical system 20 and the mask 15. S1 is the mask 15
Shows the range of use in the holes marked with.

An irradiation method by the laser processing apparatus will be described below with reference to FIG.

In the irradiation method by the laser processing apparatus, the laser beam is radiated from the laser oscillator 10 via the fiber 11 to the substrate 19 to be processed to perform the processing.

The laser beam having passed through the uniform optical system 20 passes through the hole of the mask 15 from the lens 14, passes through the imaging lens 16 which is an imaging optical system, and irradiates the substrate 19 with the laser beam. The uniform optical system 20 in this laser processing apparatus has a carbide reflector that makes the intensity distribution of laser energy uniform by multiple reflection.

An imaging optical system or a condensing optical system for irradiating the substrate 19 with a laser beam passed through the uniform optical system 20 of the laser processing apparatus. Uniform optical system 2
The laser beam passed through 0 is irradiated on the substrate 19 to be processed by an imaging optical system or a condensing optical system.

In this embodiment, a hole is drilled in the substrate 19 by irradiating the substrate 19 with a laser beam. The uniform optical system 20 is 1.5 times or more the diameter of the fiber 11 and the length is set to 5 times or more the cross-sectional dimension.

The material of the kaleid reflector is Y
In the case of an AG laser oscillator, beryllium can be considered in addition to oxygen-free copper. On the other hand, when a YAG laser oscillator or an excimer laser oscillator is used, a glass material such as quartz can be used.

The uniform optical system 20 causes a laser having a single-mode or multi-mode intensity distribution to be incident on a kaleid reflector by a condenser lens for incidence, and the kaleid reflector uses a multiple reflection inside the laser beam to make a laser beam. In order to make the energy intensity distribution uniform.

The laser beam exiting the uniform optical system is incident on a laser beam shaping mask 15 through an optical lens 14. The laser beam having a cross-sectional shape is reduced and projected by the imaging lens 16, is shaken by a scanning system called a galvano scanner, and is irradiated on the substrate 19 on the XY stage through an optical lens called an fθ lens. .

The XY stage is movable in the X-axis direction and the Y-axis direction. When the processing of one processing region of the processing substrate 19 is completed, the processing system 1
The substrate to be processed 19 is moved so that the region to be processed next to 9 is located.

The cross-sectional shape and size of the beam in the laser irradiation area are determined by the shape of the opening in the mask 15 and the imaging lens 16 for reducing and projecting the laser beam therefrom.
And the focal length of the optical lens.

In one embodiment, the substrate 19 is drilled by irradiating the substrate 19 with a laser beam. In addition to the drilling, a mask such as welding or surface treatment may be used. Even if the shape of 15 is changed, it can respond.

[0026]

As described above, the laser processing apparatus according to the present invention uses a uniform optical system so that the mode of light emitted from the fiber becomes a top hat shape.
The change in the laser energy passing through the holes in the mask can be reduced.

Further, since the laser energy intensity distribution in the laser beam irradiation area can be made uniform, it is suitable for drilling.

Further, when such a uniform optical system 20 is employed, the processing quality is stabilized in a wider range of 50% or more than the conventional one.

[Brief description of the drawings]

FIG. 1 is a view showing a schematic configuration of a laser processing apparatus according to the present invention.

FIG. 2 is a diagram showing a schematic configuration of a conventional laser processing apparatus.

[Explanation of symbols]

 Reference Signs List 10 laser oscillator 11 fiber 14 optical lens 15 mask 16 imaging lens 19 substrate to be processed 20 uniform optical system

Claims (6)

[Claims] In a laser processing apparatus for performing processing by irradiating a substrate with a pulsed laser beam from a laser oscillator through a fiber, a beam mode of the laser beam is set at a position close to an emission end of the fiber. A laser processing apparatus comprising a uniform optical system for changing the intensity distribution of laser energy to be uniform. 2. A laser processing apparatus according to claim 1, wherein said uniform optical system includes a carbide reflector for making the intensity distribution of laser energy uniform by multiple reflection. 3. The laser processing apparatus according to claim 1, further comprising an imaging optical system or a condensing optical system that irradiates the substrate with the laser beam that has passed through the uniform optical system. Characteristic laser processing equipment. 4. A method of irradiating a substrate with a pulsed laser beam from a laser oscillator through a fiber by a laser processing apparatus, wherein the laser beam is applied to a position close to an emission end of the fiber. An irradiation method using a laser processing apparatus, comprising: providing a uniform optical system that changes a beam mode to make the intensity distribution of laser energy uniform, and irradiating the substrate to be processed with the laser beam that has passed through the uniform optical system. . 5. An irradiation method by a laser processing apparatus according to claim 4, wherein the laser beam passed through the uniform optical system is irradiated on the substrate by an imaging optical system or a condensing optical system. Irradiation method using a laser processing device. 6. An irradiation method by a laser processing apparatus according to claim 4, wherein the laser beam is applied to the substrate to perform a boring process on the substrate. Irradiation method.