JP2001170791A - Method of laser machining - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of high quality laser machining by preventing the deterioration of the quality of a work due to the attachment of the working soot of a work in a laser machining of the work with a CO2 laser. SOLUTION: In the method of a CO2 laser machining for a work by using a contact mask, a protective film having an adhesive layer is adhered to a zone of the work including at least a region located at the opening part of the mask, the mask is mounted on the work in contact with each other, and the laser machining is performed simultaneously on the protective film and the work by irradiating them with the CO2 laser from the upper side of the mask.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carbon dioxide laser processing method for a workpiece using a contact mask, which suppresses the adhesion of soot, which is a by-product of laser processing, and performs laser processing for high quality processing. About the method.

[0002]

2. Description of the Related Art A laser processing method using a mask includes a conformal mask method, an off-contact mask method, and a contact mask method. The conformal mask method is a method of using a metal layer integrated with, for example, a resin film, which is a workpiece, as a mask and removing (perforating) a region where the resin film is exposed by laser light. The off-contact mask method is a method in which a metal plate or a ceramic plate which does not directly contact a resin film is used as a mask, and the resin film is removed (perforated) by laser light passing through an opening of the mask. In the contact mask method, a mask made of metal or the like is loaded in contact with a resin film, and a laser beam is irradiated from above the mask to remove (drill) the resin film in an exposed area. Is the way.

When the contact mask method is used, it is not necessary to integrate the resin film and the mask unlike the conformal mask method, so that not only the degree of freedom in selecting the resin film is increased, but also the opening pattern of the mask is not changed. Since it can be used as a processing pattern of a resin film, the processing accuracy is higher than the off-contact mask method, and the laser processing apparatus does not need to be provided with a projection device including a plurality of optical lenses. . For this reason, the contact mask method has been known as a simple, inexpensive and high-precision processing method. However, in the laser processing by the contact mask method, the following problems have been conventionally known.

Conventionally, as a mask for carbon dioxide gas laser processing on a resin film or the like, as described in, for example, JP-A-7-236990, a copper plate which is a material having a high reflectivity to a carbon dioxide gas laser beam, or a copper plate which is reinforced is used. What bonded resin has been used for the purpose. When a resin film or the like is laser-processed, the resin at the laser-irradiated portion is instantaneously decomposed and scattered as decomposed gas or soot-like dust. Depending on the pressure of the decomposition gas, etc.
A gap may be generated between the mask and the resin film. In this case, the soot-like dust enters between the mask and the resin film, adheres to the surface of the resin film, and causes a reduction in processing quality of the resin film.

One of the methods for suppressing the adhesion of soot-like dust is to use a thick metal plate as a mask so that no gap is generated between the mask and the resin film.
There is also a method of improving the adhesiveness between the mask and the resin film by using gravity, but in this case, the processing accuracy of the mask itself is deteriorated, and particularly, fine processing cannot be performed. As a result, such a mask is used. Since the precision in the laser processing method is deteriorated or fine processing becomes impossible, it is not an effective method.

[0006] There is also a method of improving the adhesion between the mask and the resin film by electrostatic force and suppressing the generation of the gap, but in this case, processed soot generated by laser processing gathers by electrostatic force, and on the contrary, soot adheres. Will promote the deterioration of quality. Further, there is a method of improving the adhesion by a magnetic force. For example, if a resin film, which is a workpiece, is loaded between a mask made of ferromagnetic material and a processing table on which magnets are placed, the mask and the resin film adhere to each other due to the magnetic force, effectively preventing soot from entering the gap. You can do it.

However, when the resin film to be processed has a structure including a diamagnetic material having a large diamagnetic susceptibility such as graphite, or when the thickness of the resin film is large, the contact mask by the magnetic force is used. In the case where the adhesion of the soot significantly decreases, it is difficult to completely suppress the entry of soot only by a method of bringing the mask into close contact with a magnetic force. Further, these masks are sometimes used for laser processing a plurality of times for the purpose of improving production efficiency. In such a case, thermal deformation of the mask becomes a non-negligible level. May be a problem. Accordingly, it has been desired to establish a laser processing method using a contact mask that can suppress the adhesion of soot even when a gap occurs between the mask and the resin film.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a high-quality laser processing method in which a carbon dioxide laser processing of a workpiece using a contact mask prevents a decrease in quality due to adhesion of processing soot to the workpiece. To provide.

[0009]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that a carbon dioxide gas laser beam is irradiated from above a contact mask which is mounted and contacted with a protective film attached to a surface of a workpiece. The inventors have found that the above problems can be solved, and have completed the present invention. That is, the laser processing method according to the present invention is directed to a method of carbon dioxide laser processing of a workpiece using a contact mask, wherein a protective film having an adhesive layer is provided in a range including at least a region located at an opening on the mask side of the workpiece. After attaching the mask, a mask is stacked on the workpiece and brought into contact with the workpiece, and a carbon dioxide laser beam is irradiated from above the mask to simultaneously laser-process the protective film and the workpiece.

In the present invention, the protective film including the adhesive layer has an absorption coefficient of 1000 at the laser oscillation wavelength.
cm ^-1 or 3000 cm ^-1 or less, the thickness of the protective film comprising an adhesive layer is 0.2mm or less than 0.005 mm, and the adhesive strength relative to the workpiece the adhesive layer 5
It is desirable that it is not less than gf / 10 mm and not more than 300 gf / 10 mm.

In the present invention, the protective film including the adhesive layer is desirably attached to both front and back surfaces of the workpiece. Further, in the present invention, it is preferable that the adhesive layer is made of an acrylic resin, and that at least a part of the protective film excluding the adhesive layer contains Japanese paper or a polyester resin.

[0012]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 shows a mask (a),
FIG. 9 is a cross-sectional view when a resin film (c), which is a workpiece to which a protective film (b) is stuck on both front and back surfaces, is loaded on the surface of a processing table (d). First, the type of a workpiece to be processed in the present invention is not particularly limited, but among them, a film or a sheet made of an epoxy resin, a polyimide resin, a cardo resin and a resin containing a precursor or a derivative thereof ( Hereinafter, a laser processing method is described for a resin film (c) as a workpiece. The resin film (c) may be composed only of a resin of a single composition, or may be a composite of a plurality of types of resins or a laminate of the resins. Further, a resin or a material in which ceramic, metal, or resin such as fibrous or particulate glass is contained in a resin may be formed into a film or sheet shape. In addition, resin film (c)
May be laminated on a support substrate that is not a target of laser processing, such as a different kind of resin or metal.

It is preferable that the thickness of the resin film (c) to be processed is 0.005 mm or more and 2 mm or less. If the resin film (c) is laminated on a support substrate that is not a target of laser processing, the thickness of the resin film including the support substrate and the like may be 0.005 mm or more. When the thickness is less than 0.005 mm, not only the handling of the resin film becomes difficult, but also bubbles and wrinkles are easily generated between the protective film (b) and the resin film when the protective film (b) is attached. It becomes difficult to perform high-quality laser processing.

The protective film (b) used in the present invention
Has an adhesive layer so that it can be stuck on the surface of the resin film to be laser-processed, does not peel off during laser processing, and can be easily peeled off from the surface of the resin film (c) after laser processing. Must be The protective film (b) is preferably made of a material that can be perforated by a carbon dioxide laser simultaneously with the resin film (c) and that generates less soot.

As such a material, the absorption coefficient at the laser oscillation wavelength of the protective film (b) including the adhesive layer is not less than 1000 cm ^{-1 and not} more than 3000 cm ^-1 , and the thickness of the protective film (b) including the adhesive layer is not limited. 0.005 mm or more and 0.2 mm or less, and the adhesive strength of the adhesive layer to the resin film (c) is 5 gf / 10 mm or more and 300 gf / 10.
mm or less is preferred. For example, a preferable example is one in which the adhesive layer is made of an acrylic resin and at least a part of the protective film excluding the adhesive layer contains Japanese paper or a polyester resin. Here, the absorption coefficient is determined by measuring the absorbance of the resin film using an apparatus capable of measuring an absorption spectrum in an infrared region such as FT-IR, and calculating from the absorbance and the measured thickness of the resin film.

The absorption coefficient of the protective film (b) is 1000
If it is less than ¹ cm ^{−1, the} amount of laser light absorbed per unit thickness of the protective film (b) is small, so that it is not completely decomposed even by laser irradiation, soot is generated from the protective film itself, Not only does the effect of suppressing the adhesion of soot to the surface of the resin film (c) decrease, but also the adhesion of soot may be promoted. When the absorption coefficient exceeds 3,000 cm ⁻¹ , the amount of laser light absorbed per unit thickness of the protective film (b) is too large, so that the resin film (c) is not irradiated with the laser light having sufficient energy. In order to process the film (c), it is necessary to irradiate a laser beam having a higher energy density, which leads to a decrease in laser processing efficiency.

Similarly, when the thickness of the protective film (b) including the adhesive layer exceeds 0.2 mm, the protective film (b)
Causes an increase in the amount of laser light absorbed, leading to a reduction in processing efficiency. When the thickness of the protective film (b) is less than 0.005 mm, as in the case where the thickness of the resin film (c) is less than 0.005 mm, not only the handling of the protective film (b) becomes difficult, but also the protective film ( When b) is adhered to the resin film (c), bubbles and wrinkles are easily generated between the protective film (b) and the resin film (c), and as a result, it becomes difficult to perform high-quality laser processing.

When the adhesive strength of the adhesive layer to the workpiece (c) is less than 5 gf / 10 mm, the assist gas, which is often used in laser processing, is blown, or the pressure of the decomposed gas generated during laser processing of the resin. For example, the protective film (b) may peel off from the resin film (c) during laser processing, soot enters the gap between the resin film (c) and the protective film (b), and the effect of suppressing soot adhesion is reduced. I do. If the adhesive strength exceeds 300 gf / 10 mm, it becomes difficult to peel off the protective film (b) from the resin film (c) after the laser processing. c)
Cracking or wrinkling of the resin film (c) causes deterioration of the quality of the resin film.

The protective film (b) has to be previously attached to the surface of a workpiece such as a resin film.
It must be attached to a region including at least a region located at the opening on the contact mask side when the mask (a) is loaded. It is desirable that the protective film (b) be stuck not only on the mask (a) side of the resin film (c) but also on the back surface thereof. When they are stacked and in contact with each other, the protective film (b) may be attached only to the surface of the mask (a) opposite to the supporting substrate or the like, and not to the supporting substrate surface. The method of attaching the protective film (b) to the resin film (c) is a method of uniformly attaching the resin film (c) and the protective film (b) so that wrinkles and bubbles do not occur between the resin film (c) and the protective film (b). There is no particular limitation, and the application may be performed by hand, or may be performed using a device such as a roll laminator.

The resin film (c) to which the protective film (b) is adhered is placed on a processing table (d) arranged at a laser irradiation part of a laser processing machine, and a mask (a) is further loaded on the surface thereof. Contact. Processing table (d)
The shape and material of the workpiece are not particularly limited, but the surface on which the workpiece (c) is placed must be flat. In order to prevent the processing table (d) from being damaged by the laser light, a plate material that absorbs or reflects the laser light may be interposed between the resin film (c) and the processing table (d). Examples of such a plate include a copper plate, but are not particularly limited.

The laser beam from the laser beam machine is preferably a carbon dioxide laser beam having a wavelength matching the absorption band of the resin film (c). In this case, the laser light to be applied may be pulsed light or continuous wave light as long as the laser light has a wavelength range of 9 μm to 11 μm. The method of irradiating the laser beam is such that the protective film (b) exposed at least in the opening (e) of the mask (a)
The material is not particularly limited as long as it is applied to the entire area of the resin film (c) on which is adhered. For example, the laser beam may be swept using a drive mirror sweeping device such as a galvanometer mirror or a polygon mirror, or the working table (d) may be moved. It may be performed by the method of performing.

The laser irradiation may be performed while blowing a gas such as an assist gas, or a dust collecting port for sucking generated processing soot may be provided near the laser irradiation point. After the laser irradiation, the protective film (b) must be peeled off from the resin film (c). The method of peeling is not particularly limited as long as it does not cause cracks or wrinkles in the resin film (c). For example, it may be peeled off by hand or by an automatic method such as a winding method. In addition, as a use of a laser processed product obtained by the laser processing method of the present invention, for example, a resin film, an insulating layer used for a circuit board and the like can be mentioned.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail based on embodiments. Example A resin film composed of polyimide having a length of 300 mm, a width of 250 mm and a thickness of 0.05 mm was provided on both surfaces with a height of 280.
A protective film having a size of mm × 240 mm × 0.067 mm in thickness was stuck at room temperature using a roll laminator. The protective film is composed of a layer made of Japanese paper and a layer made of an acrylic adhesive. The adhesive strength of the adhesive layer to the polyimide resin film was 197 gf / 10 mm. The absorption coefficient of the above protective film at a wavelength of 9.6 μm was 1700 cm −1. FT manufactured by JASCO Corporation was used for measuring the absorbance for calculating the absorption coefficient.
/ IR-620 was used.

The laser processing machine used was a carbon dioxide laser oscillator tuned to oscillate a laser having a wavelength of 9.6 μm, a convex lens made of ZnSe, a galvano mirror scanner capable of sweeping a laser beam in one direction, and a one-way scanner. It is composed of an aluminum processing table that can move at a constant speed of 550 mm in length and 400 mm in width, an assist gas blowing nozzle that is arranged so that the assist gas is blown to the laser irradiation part, and a dust collection port that collects the generated soot. Is done. On the surface of the processing table, 550 mm long x 400 wide
A copper foil with a size of 0.01 mm x 0.018 mm is placed, a polyimide film with protective films attached on both surfaces is placed on top of it, and a mask of 350 mm length x 300 mm width is placed on top of it and brought into contact. Was. The mask comprises a copper layer having a thickness of 35 μm, a layer made of epoxy resin and glass cloth having a thickness of 200 μm, and a copper layer having a thickness of 35 μm.
An R-4 plate provided with a predetermined opening by an NC router, which is a mechanical drilling machine controlled by a computer, was used.
The openings were a plurality of circular patterns with a diameter of 0.5 mm to 20 mm and a plurality of square patterns with a side of 0.5 mm to 20 mm within a range of 250 mm × 200 mm of the mask.

The mask was fixed to a processing table with a commercially available adhesive tape so as not to be blown off by an assist gas or the like. At this time, the pressure-sensitive adhesive tape was disposed in a portion not irradiated with the laser. A continuous oscillation laser beam having a wavelength of 9.6 μm swept by a galvanomirror scanner while blowing assist gas and sucking from a dust collecting port is applied to a mask surface including a mask opening, which is 250 mm long × 200 mm wide.
Irradiation was carried out without any gap in the range, and the polyimide film including the protective film was etched. Thereafter, the protective film was manually peeled off from both sides of the polyimide film, and the laser processing was completed. No adhesion of soot generated by the processing was observed on the processed polyimide film surface, and laser processing of good quality could be performed.

Comparative Example As a result of performing laser processing under the same conditions except that protective films were not attached to both surfaces of the resin film composed of polyimide in the example, the surface of the processed polyimide film was generated by processing. Soot deposition was observed.

[0027]

According to the present invention, it is possible to provide a high-quality laser processing method which can prevent deterioration in quality due to the adhesion of processed soot to a resin film in laser processing of a resin film using a contact mask method. Can be.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a state in which a resin film having a contact mask and a protective film attached thereto is mounted on a processing table surface.

[Brief description of reference numerals]

 a contact mask b protective film c resin film d working table e opening

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoshifumi Yoshizawa 1 Tsukiji, Kisarazu-shi, Chiba Electronic Materials Development Center, Nippon Steel Chemical Co., Ltd. (72) Inventor Shoichi Ii 1 Tsukiji, Kisarazu-shi, Chiba Shinnichi 4E068 AF01 CD10 CF00 CF01 CF03 DB09 DB10

Claims (4)

[Claims] In a carbon dioxide laser processing method for a workpiece using a contact mask, after a protective film having an adhesive layer is attached to a range including at least a region located at an opening on the mask side of the workpiece. A mask is mounted on the workpiece and brought into contact with the workpiece, and the protective film and the workpiece are simultaneously laser-processed by irradiating a carbon dioxide laser beam from above the mask. 2. The protective film containing an adhesive layer has an absorption coefficient at a laser oscillation wavelength of 1000 cm ^-1 or more and 3000 or more.
cm ^-1 or less, the thickness is 0.005 mm or more and 0.2 mm or less, and the adhesive strength of the adhesive layer to the workpiece is 5 g.
The laser processing method according to claim 1, wherein the thickness is not less than f / 10 mm and not more than 300 gf / 10 mm. 3. The laser processing method according to claim 1, wherein a protective film including an adhesive layer is attached to both front and back surfaces of the workpiece. 4. The laser processing method according to claim 1, wherein the adhesive layer is made of an acrylic resin, and at least a part of the protective film excluding the adhesive layer contains Japanese paper or polyester resin. .