JP2002035985A - Device and method for laser beam machining - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device and method for laser beam machining which can prevent rise of running costs. SOLUTION: Laser beams are irradiated by a carbon dioxide gas laser oscillator A stage 7 holds a work object 6. The laser beam is condensed by a condenser lens 4 for irradiating from the carbon dioxide gas laser oscillator into the work object held in a stage. A protection film formed of a polyolefin is disposed in an optical path of laser beam between the condenser lens and the stage.

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 and a laser processing method for processing a laser beam by focusing the laser beam on the workpiece using a condenser lens. The present invention relates to a laser processing apparatus and a processing method having a protective member that prevents the laser lens from adhering to an optical lens.

[0002]

2. Description of the Related Art There is known a laser processing method in which an infrared laser such as a carbon dioxide gas laser is condensed on an object to be processed by a condensing lens to form a hole. When drilling a metal film etc.,
Fine metal particles having a diameter of about several tens of micrometers are scattered from the object to be processed. In order to prevent the scattered matter from adhering to the condenser lens, a protection plate is arranged between the condenser lens and the object to be processed.

[0003]

When scattered matter from the object adheres to the protection plate, the transmittance of the laser beam is reduced. Therefore, the protection plate must be periodically replaced. Conventionally, ZnSe having a high transmission coefficient in the infrared region has been used as a material for the protective plate. Since the ZnSe plate is expensive, the running cost increases.

An object of the present invention is to provide a laser processing apparatus and a processing method capable of preventing a rise in running cost.

[0005]

According to one aspect of the present invention, a carbon dioxide laser, a stage for holding an object to be processed, and a laser beam emitted from the carbon dioxide laser are supplied to the processing object held by the stage. There is provided a laser processing apparatus comprising: a condenser lens for condensing light on an object; and a protection film disposed in an optical path of a laser beam between the condenser lens and the stage and formed of polyolefin.

The scattered objects scattered from the processing object collide with the protective film and do not reach the condenser lens. For this reason, it is possible to prevent the condensing lens from being stained by flying objects. When the protective film becomes dirty, it is possible to prevent a decrease in transmittance due to dirt by replacing the protective film with a new protective film or moving the protective film to use a clean area.

[0007]

FIG. 1A is a schematic diagram of a laser processing apparatus according to a first embodiment. Laser light source 1 emits a pulsed laser beam pl _0. The laser light source 1 is, for example, TEA (Transversely Excited Atmospheric Press).
ure) mode CO ₂ laser oscillator. Note that another laser oscillator may be used as the laser light source 1.
For example, an RF-CO ₂ laser oscillator can be used. The pulse laser beam pl ₀ is reflected by the return mirror 2 and enters the galvano scanner 3. The galvano scanner 3 swings the optical axis of the laser beam in a two-dimensional direction.

The pulse laser beam that has passed through the galvano scanner 3 is focused on the surface of the object 6 by the fθ lens 4. lens 4 is supported by a lens holder 10. The workpiece 6 is placed on an XY stage 7. The XY stage 7 can move the workpiece 6 in a two-dimensional direction parallel to its surface. When the galvano scanner 3 swings the optical axis of the laser beam, the laser beam can be focused on an arbitrary point in a square area having a side length of 50 mm.

The processing object 6 is, for example, a laminated wiring board in which resin layers and copper layers are alternately laminated. When the laser beam is focused on the surface of the processing target 6, a hole is formed in the copper layer or the resin layer at the focal point. By shaking the optical axis of the laser beam with the galvano scanner 3, a hole can be formed at an arbitrary point in a square area having a side length of 50 mm.
By moving the workpiece on the XY stage 7,
Holes can be drilled at any point in a larger area.

A protective film 5 made of polyethylene and having a thickness of about 12 μm is disposed between the fθ lens 4 and the object 6 to be processed. The protective film 5 is paid out from the pay-out roll 20, passes between the fθ lens 4 and the object 6, and is taken up by the take-up roll 23. The take-up roll driving device 25 rotates the take-up roll 23 at a predetermined speed. For example, the protective film 5 is wound at a constant speed of 2 mm per minute.

Feeding roll 20 and winding roll 2
Reference numeral 3 is arranged at a position higher than the surface of the fθ lens 4 on the processing object 6 side with respect to the XY stage 7.
A support bar 21 is arranged below the unwinding roll 20, and a support bar 22 is arranged below the take-up roll 23. Since the protective film 5 is stretched between the support rods 21 and 22, the protective film 5 is held substantially horizontally below the fθ lens 4, and the height from the XY stage 7 to the protective film 5 is defined. .

The laser beam converged by the fθ lens 4 passes through the protective film 5 and irradiates the surface of the workpiece 6. According to the evaluation experiment of the present inventors, the transmittance of the protective film 5 was about 95%. If the transmittance of the protective film 5 is 80% or more, it is considered that there is no significant effect on laser processing.

When the protective film 5 is brought closer to the object 6, the beam diameter of the laser beam at the position where the protective film 5 is arranged becomes smaller. For this reason, the protection film 5 is easily damaged by the laser beam irradiation.
Therefore, it is preferable that the protective film 5 is arranged at a position close to the fθ lens 4. For example, from the processing object 6 to f
It is preferable to hold the protective film 5 at a position higher than ３ of the height to the surface of the θ lens 4.

When a hole is made in a metal film such as copper, fine metal particles are scattered. Since the fine particles are blocked by the protective film 5, it is possible to prevent the metal fine particles from adhering to the expensive fθ lens 4. Since the protective film 5 is wound at a predetermined speed, the metal fine particles adhering to the protective film 5 move out of the optical path of the laser beam after a certain period of time. For this reason, the transmittance of the protective film 5 can be maintained at a desired value or more.

When a hole is formed in the resin layer, the resin is vaporized,
Gas is generated. When this gas reaches the surface of the fθ lens 4, the lens surface is contaminated. FIG. 1 (A)
As shown in FIG. 1, the feed roll 20 and the take-up roll 23 are disposed above the surface of the fθ lens 4 and the side surfaces on both sides of the lens holder 10 (the surface perpendicular to the paper surface in FIG. 1A). By covering with the protective film 5, it is possible to prevent gas from flowing in from these two directions.

Note that a side surface not covered with the protective film 5 (a surface parallel to the paper surface in FIG. 1) may be covered with a thin plate or the like. This makes it possible to more effectively prevent gas from flowing around.

Further, a protective film 5 made of polyethylene
Is cheaper than a protective plate made of ZnSe, so that the running cost can be reduced.

In the above embodiment, the protective film 5 made of polyethylene is used, but a protective film made of another polymer material may be used. However, the thickness is preferably such that the transmittance in the wavelength region of the laser used for processing is 80% or more. For example, a polyolefin resin can be used as a material for the protective film. According to the experiment of the present inventor, a relatively high transmittance was able to be secured when polypropylene was used.

In the first embodiment, the protective film 5 wound around a roll is used. However, the protective film 5 may be attached to a support member such as a window frame. In this case, the protective film 5 cannot be wound up, but if the protective film 5 becomes dirty, the entire support member may be replaced.

In the above embodiment, the case where the protective film 5 is used as a single layer has been described, but a plurality of protective films may be stacked. Even if one protective film is broken, the other protective film protects the fθ lens, so that the reliability of the protective film can be improved.

FIG. 2 is a schematic view of a laser processing apparatus according to a second embodiment of the present invention. In the first embodiment, the protection film 5 is held substantially horizontally below the fθ lens 4, but in the second embodiment, the protection film 5 is held obliquely with respect to the optical axis of the laser beam. ing. The other configuration is the same as the configuration of the first embodiment shown in FIG.

When the protective film 5 is arranged obliquely, the energy of the laser beam applied per unit area of the protective film 5 becomes small. For this reason, damage to the protective film 5 can be suppressed.

FIG. 3 is a schematic view of a laser processing apparatus according to a third embodiment of the present invention. In the third embodiment, the protective film 5 includes the feeding roll 20 and the winding roll 23.
It is in a state of being freely hung between them. By synchronizing the rotation of the pay-out roll 20 with the rotation of the take-up roll 23, the protective film 5 can be wound while maintaining the sagging state of the protective film 5.

Since the protective film 5 is freely hung, the impact when the metal fine particles collide with the protective film 5 is reduced. In addition, according to the evaluation experiment of the present inventor, it was found that the transmittance when no tension was applied to the protective film 5 was slightly larger or almost equal to the transmittance when a certain amount of tension was applied. .

FIG. 4 is a perspective view of a protective film of a laser processing apparatus according to a fourth embodiment of the present invention. The protective film 5 fed downward from a feed roll (not shown) is folded back by a support rod 21a curved upward. The protective film 5 folded back by the support rod 21a is
The support rods 22b that are bridged between the support rods 21b and 22b that are curved downward and that are further curved upward.
It is folded back at a and wound up by a winding roll (not shown).

The support rods 21b and 2 curved downwardly
2b is disposed between the fθ lens 4 and the object 6 to be processed. For this reason, at the intersection of the protective film 5 and the laser beam, the intersection line between the virtual plane perpendicular to the moving direction of the protective film 5 and the protective film 5 becomes a convex curve toward the workpiece 6 side. . This makes it possible to reduce the flow of gas generated from the processing location of the processing target 6.

FIG. 5 is a perspective view of a protective film of a laser processing apparatus according to a fifth embodiment. Support rods 21 and 2 of the laser processing apparatus according to the first embodiment shown in FIG.
Instead of 2, corrugated support bars 21A and 22A are used. Therefore, at the intersection of the protective film 5 and the laser beam, the protective film 5 undulates in a direction orthogonal to the traveling direction. Thereby, the protective film 5
, The energy of the laser beam applied per unit area is reduced, and damage to the protective film 5 can be suppressed.

FIGS. 6A and 6B are a front view and a plan view, respectively, of a protective film of a laser processing apparatus according to a sixth embodiment. As shown in FIG. 6A, the protective film 5 is stretched over a plurality of support rods 30a to 30g in order. Odd-numbered support rods 30a, 30c, 30
e and 30g are even-numbered support rods 30b, 30d,
And below 30f (position away from fθ lens 4)
Are located in When viewed from vertically above, the support bars 30a to 30g are arranged at equal intervals. The protective film 5 includes odd-numbered support rods 30a, 30c, 30e,
And 30g underneath, and the even-numbered support rod 30b,
It passes above 30d and 30f. For this reason,
The protective film 5 undulates in the traveling direction.

As shown in FIG. 6B, support rods 3 at both ends are provided.
Each of 0a and 30g is one rod passed in the width direction of the protective film 5. Other support rods 3 arranged inside
Ob to 30f are not disposed at the center in the width direction of the protective film 5 but are disposed only near the edge of the protective form 5 so as not to block the laser beam.

In the sixth embodiment, as in the case of the fifth embodiment, the protective film 5 is wavy. For this reason, the energy of the laser beam irradiated per unit area of the protective film 5 decreases, and damage to the protective film 5 can be suppressed.

FIG. 7A shows a configuration near a fθ lens of a laser processing apparatus according to a seventh embodiment of the present invention. The fθ lens 4 is held by the lens holder 10A. A protection plate 31 is attached to the lens holder 10 further outside (the processing object 6 side) than the fθ lens 4. The protection plate 31 is formed of, for example, ZnSe. The surface of the fθ lens 4 on the processing object 6 side is formed by the protection plate 31.
It is isolated from the space where the object 6 is arranged.

The protection film 5 is arranged below the protection plate 31. The laser beam converged by the fθ lens 4 passes through the protection plate 31 and the protection film 5 and is irradiated on the surface of the processing target 6. Since the protection plate 31 separates the surface of the fθ lens 4 from the space in which the processing object 6 is arranged, the gas generated by the processing causes the fθ lens 4
Does not reach the surface. Therefore, contamination of the surface of the fθ lens 4 can be prevented. Since the protective film 5 is disposed below the protective plate 31, the fine metal particles scattered from the object 6 are blocked by the protective film 5. Therefore, the frequency of replacement of the protection plate 31 can be reduced as compared with the case where the protection film 5 is not provided.

As shown in FIG. 7B, another protective film 32 may be adhered to the surface of the fθ lens 4 instead of disposing the protective plate 31. As the material of the protective film 32, the same polymer material as polyethylene as the protective film 5 can be used.

FIG. 8 shows a schematic view of a laser processing apparatus according to the eighth embodiment. As in the case of the second embodiment, the protective film 5 is arranged obliquely with respect to the optical axis of the laser beam. The observation light source 35 irradiates an observation light beam 36 to a position of the protective film 5 where the laser beam is transmitted. The light receiving device 37 receives the observation light beam 36 transmitted through the protective film 5. As the observation light source 35, for example, a HeNe laser oscillator can be used.

By measuring the amount of attenuation of the observation light beam 36 with the light receiving device 37, the degree of contamination of the protective film 5 can be known in real time. When the degree of dirt exceeds the reference value, the protective film 5 is moved so that the processing laser beam passes through the dirt-free or dirt-free area of the protective film 5. Thereby, a decrease in the energy of the processing laser beam can be suppressed. Further, the winding speed of the protective film 5 may be changed according to the degree of dirt. For example, when the dirt becomes severe, it is preferable to increase the moving speed of the protective film 5.

FIG. 9 shows an arrangement of a protective film of a laser processing apparatus according to a ninth embodiment of the present invention. FIG. 9 is a plan layout view of the protection film viewed from vertically above.

As in the case of the laser processing apparatus according to the first embodiment shown in FIG. 1A, the protective film 5 is unwound from the unwinding roll 20 and is wound under the fθ lens 4 onto the winding roll 23. Can be The protection film 5
In FIG. 9, it moves in the horizontal direction.

Further, another protective film 45 is unwound from another unwinding roll 40, and is wound up by another winding roll 41 under the fθ lens 4. The protection film 45 moves in the vertical direction in FIG. 9, that is, the direction perpendicular to the moving direction of the protection film 5. fθ
Since the lens 4 is protected by the two protective films 5 and 45, the lens protective effect can be ensured even if one of the protective films is damaged.

In the ninth embodiment, FIG.
Almost the entire periphery of the side surface of the lens holder 10 shown in (A) is covered with the protective film 5 or 45. For this reason, the effect of preventing the gas generated from the processing location of the processing target 6 from flowing around can be enhanced.

The present invention has been described in connection with the preferred embodiments.
The present invention is not limited to these. For example, it will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

[0041]

As described above, according to the present invention,
Since scattered matter from the object to be processed is shielded by the polymer protective film, it can be prevented from reaching the condenser lens.
Since the polymer protective film is inexpensive, the running cost of the device can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic view of a laser processing apparatus according to a first embodiment,
And a side view according to a modification thereof.

FIG. 2 is a schematic view of a laser processing apparatus according to a second embodiment.

FIG. 3 is a schematic view of a laser processing apparatus according to a third embodiment.

FIG. 4 is a schematic view of a laser processing apparatus according to a fourth embodiment.

FIG. 5 is a schematic view of a laser processing apparatus according to a fifth embodiment.

FIG. 6 is a schematic view of a laser processing apparatus according to a sixth embodiment.

FIG. 7 is a schematic view of a laser processing apparatus according to a seventh embodiment.

FIG. 8 is a schematic view of a laser processing apparatus according to an eighth embodiment.

FIG. 9 is a schematic view of a laser processing apparatus according to a ninth embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Laser light source 2 Folding mirror 3 Galvano scanner 4 fθ lens 5 Protective film 6 Object to be processed 7 XY stage 10 Lens holder 20, 40 Feeding roll 21, 22 Support rod 23, 41 Take-up roll 25 Driver 26 Thin plate 30a to 30g Support Rod 31 Protective plate 32 Protective film 35 Observation light source 36 Observation light beam 37 Light receiving device 45 Other protective film

Claims (9)

[Claims] A carbon dioxide laser oscillator; a stage for holding a workpiece; a condenser lens for focusing a laser beam emitted from the carbon dioxide laser on a workpiece held on the stage; A laser processing apparatus having a protective film made of polyolefin, which is disposed in an optical path of a laser beam between a condenser lens and the stage. 2. The image forming apparatus according to claim 1, further comprising a pay-out roll and a take-up roll, wherein the protective film is wound around the pay-out roll, and the protective film fed from the pay-out roll is connected to the condenser lens and the stage. The laser processing apparatus according to claim 1, wherein the laser beam passes through an optical path of the laser beam and is wound by the winding roll. 3. The laser processing apparatus according to claim 2, further comprising a roll drive mechanism for rotating the take-up roll and winding the protection film. 4. A laser oscillator, a stage for holding an object to be processed, a condensing lens for condensing a laser beam emitted from the laser oscillator on an object held on the stage, A laser disposed in an optical path of the laser beam between the lens and the stage, formed of a polymer material, and having a protective film inclined at an intersection with the laser beam with respect to an optical axis of the laser beam; Processing equipment. 5. A laser oscillator, a stage for holding an object to be processed, a condenser lens for condensing a laser beam emitted from the laser oscillator on an object held on the stage, A protection film disposed in an optical path of the laser beam between the lens and the stage, formed of a polymer material, and inclined at an intersection with the laser beam with respect to an optical axis of the laser beam; A laser processing apparatus comprising: an observation light source that irradiates a position on the film through which the laser beam passes with an observation light beam; and a light receiving device that receives the observation light beam transmitted through the protective film. 6. A laser beam is emitted from a carbon dioxide gas laser oscillator, transmitted through a condensing lens and a protective film made of polyolefin in this order, and condensed on an object to be processed.
A laser processing method for processing the processing object. 7. The laser processing method according to claim 6, further comprising a step of moving the protective film in a direction intersecting the optical axis of the laser beam. 8. The method according to claim 7, further comprising the step of observing the degree of dirt on the protective film, wherein the step of moving the protective film changes a moving speed according to the degree of dirt on the protective film.
2. The laser processing method according to 1. above. 9. The processing object according to claim 6, wherein the processing object is a substrate on which a metal layer and a resin layer are laminated, and the step of processing the processing object includes a step of making a hole in the metal layer. The laser processing method according to any one of the above.