JP2003251486A - Repeated machining method and device by pulsed laser beam - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stabilize machining quality in the repeated machining of a workpiece by a pulsed laser beam. <P>SOLUTION: With air 32 blown at a machining point 8A, ablation plume 18 rising from the machining point is removed, thereby a pulsed laser beam 16 is prevented from diffusing. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a repetitive processing method and apparatus using a pulsed laser, and more particularly to a columnar plasma (ablation) rising from a processing point, which is suitable for use in a laser drilling machine for processing a printed circuit board. The present invention relates to a repetitive processing method and apparatus using a pulse laser capable of preventing laser light from being diffused by a plume) and improving processing quality.

[0002]

2. Description of the Related Art A pulse oscillation type laser beam is used to accurately form through holes and via holes with a diameter of 0.1 mm or less, which are miniaturized with the recent miniaturization and high functionality of printed wiring boards. A laser drilling machine for forming small diameter holes has been put into practical use.

In this laser drilling machine, as shown in FIG. 1, usually, a pulse laser is scanned within a predetermined scanning area by a scanner 12 of a predetermined processing head 10 using, for example, a galvanometer mirror (not shown). Light 16
The f.theta. lens 14 is used to apply the workpiece 8 perpendicularly to the processing point 8A.

[0004]

However, in such a laser drilling machine, when the laser beam is repeatedly machined by a pulse laser having a high repetition frequency of, for example, 10 kHz or more, the ablation plume 18 is located above the machining point 8A.
Before disappears, the next pulse reaches the processing point, and the laser light is diffused due to the plume 18. As a result, there is a problem in that variations in the machined shape occur and the diameter of the machined hole suddenly increases or deforms, making it impossible to form a uniform hole.

The air blow to the work piece 8 has been conventionally performed, but this is mainly to prevent the fθ lens 14 from being contaminated due to sublimation of the work piece 8 or dust to be left in a cleaning room or the like. It was intended to prevent its diffusion into the atmosphere, not to remove the ablation plume.

The present invention has been made to solve the above-mentioned conventional problems, and an object thereof is to prevent laser light from being diffused by an ablation plume and stabilize the processing quality.

[0007]

According to the present invention, when a workpiece is repeatedly processed by a pulse laser, for example, as shown in FIG.
The above-mentioned problem is solved by spraying the above to remove the ablation plume 18 rising from the processing point 8A.

Here, as shown in FIGS. 3 (A) and 3 (B),
It is desirable that the flow rate of the air is 1 l / min or more and the flow rate is 1 m / sec or more.

Generally, the variation in the diameter of the machined hole is about 1.7 μm, so that the machining quality can be kept stable by setting the above flow rate and flow velocity.

Further, the flow rate is 50 l / min or more and the flow rate is 15
It is desirable to set it to m / sec or more. In this range, the variation in the diameter of the machined hole is saturated, so that the machined quality can be kept more stable.

The present invention also provides a repetitive machining apparatus for repetitively machining a work piece with a pulse laser, comprising a blowing nozzle for blowing air to the machining point and removing an ablation plume rising from the machining point. As a result, the above problem is also solved.

Further, air is blown out from the spray nozzle to prevent the processing head from being contaminated, and the construction is simplified.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention applied to a laser drilling machine for printed circuit boards will be described in detail below with reference to the drawings.

As shown in FIG. 4, the first embodiment of the present invention is a laser boring machine for boring a large number of holes in a workpiece 8 in a scanning area 9 with a pulse laser as shown in FIG.
The linear air 3 is uniformly applied to the processing point 8A in the scanning area 9 where the pulsed laser light is scanned by the scanner 12 shown in FIG.
2, a tubular spray nozzle 30 for removing the ablation plume 18 rising from the processing point, and a dust collecting nozzle 40 for collecting the air 32 blown from the spray nozzle 30. It is a thing.

A linear air 3 is attached to the spray nozzle 30.
A slit 31 for blowing out 2 is formed. In addition, instead of the slit 31, the processing point 8A of the workpiece 8
You may form the nozzle hole corresponding to the position of.

As the pulse laser light, for example, a high frequency, high peak pulse laser light oscillated by a Q switch from an all-solid-state laser having a frequency of 10 KHz or more, a peak power of 500 W or more, a pulse width of 500 ns or less and a wavelength of 1064 nm or less is used. be able to.

In this way, a linear air blow 32 is created by the blowing nozzle 30 and the entire scanning area 9 of the fθ lens 14 is uniformly blown, whereby the ablation plume 18 in the scanning area 9 is surely removed. be able to. Therefore, the diffusion of the next pulsed light due to the ablation plume is eliminated, and it is possible to prevent the sudden formation of a large-diameter hole or a deformed hole in the scanning area 9 and form a uniform hole.

Next, the second embodiment of the present invention will be described in detail.

In this embodiment, as shown in FIG.
A slit 33 for spraying air 34 to the fθ lens 14 is further added to the spray nozzle 30 similar to that of the embodiment.

According to this embodiment, both the air blow 32 for removing the ablation plume 18 and the air blow 34 for preventing the fθ lens 14 from being contaminated can be blown out from the single blowing nozzle 30. The configuration can be simplified as compared with the case where dedicated spray nozzles are provided. The air blow 32 for removing the ablation plume 18 and the air blow 34 for preventing the fθ lens 14 from being contaminated can be blown out from independent blowing nozzles.

In the above description, the present invention was applied to a laser drilling machine for printed circuit boards, but the application of the present invention is not limited to this, and fine processing of metal or penetration processing of silicon wafers is possible. Etc. can be similarly applied.

[0022]

According to the present invention, the ablation plume rising from the processing point can be removed to prevent the laser light from being diffused by the ablation plume, and the processing quality can be stabilized.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a main part showing a periphery of a processing head of a laser drilling machine for explaining a conventional problem

FIG. 2 is a cross-sectional view showing the periphery of a machining head of a laser drilling machine for explaining the principle of the present invention.

FIG. 3 is a diagram showing an example of a relationship between air flow rate and flow velocity and machining diameter variation in the present invention.

FIG. 4 is a perspective view showing the periphery of a workpiece of a laser drilling machine to which the present invention is applied.

FIG. 5 is a perspective view of an essential part showing the periphery of the workpiece of the second embodiment as well.

[Explanation of symbols]

8 ... Workpiece 8A ... Processing point 9 ... Scanning area 10 ... Machining head 12 ... Scanner 14 ... fθ lens 16 ... Pulse laser light 18 ... Ablation plume 20, 30 ... Spray nozzle 31, 33 ... Slit 32, 34 ... Air (blow)

Claims (5)

[Claims] 1. A repetitive machining method using a pulse laser, wherein air is blown to a machining point to remove an ablation plume rising from the machining point when the workpiece is repeatedly machined by the pulse laser. 2. The flow rate of the air is 1 l / min or more and the flow rate is 1
The repetitive processing method with a pulse laser according to claim 1, wherein the repetitive processing speed is at least m / sec. 3. The repetitive processing method with a pulse laser according to claim 1, wherein the flow rate of the air is 50 l / min or more and the flow rate is 15 m / sec or more. 4. A repetitive processing apparatus for repetitively processing a workpiece by a pulse laser, comprising a blowing nozzle for blowing air to a processing point and removing an ablation plume rising from the processing point. Repetitive processing equipment with pulsed laser. 5. A repetitive processing apparatus using a pulse laser according to claim 4, wherein air for preventing the processing head from being contaminated is also blown from the spray nozzle.