JP2002178180A - Device and method of laser beam machining - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the machining device and method producing no deposits like grains of glass solidified after melting on the inner wall of a via hole, in drilling a ceramic green sheet. SOLUTION: A workpiece, which is composed of a ceramic green sheet 1 and a resin film 2 installed on the rear side of the sheet 1, is irradiated by a pulsed laser beam with such number of shots that penetrate the ceramic green sheet 1 and that vaporize a part of the resin film 2 without penetrating it.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a laser processing apparatus and a laser processing method.

[0002]

2. Description of the Related Art FIG. 5 is a diagram showing a schematic configuration diagram showing a processing form in a conventional laser processing method, and FIG. 6 is an operation explanatory view in the embodiment shown in FIG. 7-
It is disclosed in 193375. 5 and 6, 1 is a ceramic green sheet, 2 is a resin film, 3 is a hole for a via hole, 4 is a processing table, 5 is a suction hole, and 6 is a deposit.

[0003] The ceramic green sheet 1 is placed on a processing table 4 with its entire back surface protected by a resin carrier film 2 and fixed by suction through a suction hole 5. A via hole 3 having a desired diameter is formed by irradiating a laser beam and melting and vaporizing an irradiated portion.

[0004] The electrical connection between the layers in the ceramic multilayer substrate is made via the via holes formed as described above. As a method for manufacturing a ceramic multilayer substrate having via holes, first, a hole is formed at a desired position in an unfired ceramic green sheet, and then the hole is filled with a metal paste, and then laminated and fired.

[0005]

However, in the conventional laser processing method as described above, when drilling a ceramic green sheet, a glass particle-like deposit 6 (hereinafter, referred to as a melt) solidified on the inner wall of the via hole 3. , Molten deposits). The ceramic green sheet 1 is mainly composed of ceramic particles having a high melting point, for example, alumina particles of 1 to 2 μm, glass particles, and a resin binder as a binder. As the ratio of the glass component increases, the amount of the molten deposit 6 increases. Further, when the aspect ratio (= hole depth / hole diameter) of the via hole 3 to be processed becomes larger than 2, the molten deposit tends to increase. In some cases, the molten deposits on the inner wall of the via hole sometimes hindered filling of the via hole with the conductive paste.

An object of the present invention is to provide an apparatus for stably forming a hole for a via hole having a high aspect ratio without leaving any deposits on the inner wall of the ceramic green sheet.

[0007]

According to a first aspect of the present invention, there is provided a laser processing apparatus for forming a through hole in a workpiece by superimposing an auxiliary workpiece on a back surface of the workpiece. In the apparatus, a laser unit that emits a laser beam, an input unit for inputting a material, a plate thickness, and a hole diameter of an auxiliary workpiece, and controlling the laser unit based on data input to the input unit, the auxiliary unit And a control unit for forming a through hole in the workpiece without penetrating the workpiece.

In the laser processing apparatus of the second invention, the workpiece may be a ceramic green sheet.

In a third aspect of the present invention, the thickness of the workpiece is input to the input section, and the control section determines the number of shots of the laser beam at the time of forming each through hole to determine the thickness of the workpiece. The laser unit may be controlled so as to change according to the degree.

[0010] In the laser processing apparatus according to a fourth aspect of the present invention, the control unit may be configured such that a processing depth processed by one-shot laser irradiation is equal to or less than の of a thickness of the auxiliary workpiece.
The laser beam irradiation condition of the laser unit may be set.

In a laser processing apparatus according to a fifth aspect of the present invention, the laser unit may output at least one of a carbon dioxide laser beam, a YAG laser beam, and an excimer laser beam.

A laser processing method according to a sixth aspect of the present invention is a laser processing method in which an auxiliary workpiece is overlapped on the back surface of the workpiece and a through hole is formed in the workpiece, wherein a shot pulse laser beam is emitted from a laser unit. In addition, the auxiliary workpiece is partially vaporized without penetrating the workpiece, thereby forming a through hole in the workpiece.

In a laser processing method according to a seventh aspect of the present invention, the auxiliary workpiece may be a resin auxiliary carrier film.

In the laser processing method according to an eighth aspect of the present invention, the workpiece may be a ceramic green sheet having a resin carrier film mounted on the back surface, and the auxiliary workpiece may be a resin auxiliary film.

According to a ninth aspect of the present invention, the resin auxiliary film is made of polyethylene terephthalate (PET), vinyl chloride (PVC), polyethylene (P
E) Any one or more of acrylic resins may be included.

In the laser processing method according to a tenth aspect of the present invention, when forming each of the through holes, a laser beam is irradiated for a plurality of shots, and a time interval between the shots is at least as long as the processed point is solidified after melting. It may be empty.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a schematic configuration diagram showing a first embodiment according to the present invention, in which 10 is an input unit, 20 is a control unit, 30 is a laser unit,
5 is the same as FIG. In the laser processing apparatus according to the present embodiment having the above-described configuration, the ceramic green sheet 1 is used as a workpiece, and an auxiliary workpiece of the resin film 2 is superimposed on the back surface of the ceramic green sheet 1 without passing through the auxiliary workpiece. A through hole is formed in the workpiece. The control unit 20 controls the laser unit 30 by executing a program stored in an internal or external storage medium as described below.

The laser unit 30 has a pulse oscillation C
An O ₂ laser or the like is used, and the emitted laser light has a desired processing hole diameter and a green sheet 1 to be processed.
Is set to focus on Laser unit 3
The characteristics of an oscillator of 0 are output 100 W, pulse frequency 10
It is a device that can irradiate up to 5000 Hz, pulse width of 1 to 252 μsec, high output, and short pulse.

The input part 10 of the laser processing apparatus is inputted by the operator with the material and thickness of the ceramic green sheet 1, the hole diameter of the via hole 3 and the coordinates of the hole position. Based on the input data, the control unit 20 determines the set values of the irradiation pulse energy of the pulse oscillator, the pulse width, the pulse frequency and the like, and sends them to the laser unit 30. These set values are set so as not to penetrate the auxiliary workpiece. Then, the laser unit 30 emits a predetermined laser beam based on these data and irradiates the green sheet 1 to process the via hole 3.

The control unit 20 adjusts the laser beam emitted from the laser unit 30 to a predetermined beam diameter by using a mask based on the hole diameter data from the input unit 10.
The focusing lens is set so as to be focused on the ceramic green sheet 1.

Based on the position data from the input unit 10, the control unit 20 appropriately moves the processing table 4 in the X and Y directions while changing the direction through the galvanomirror, and places the via hole 3 at a desired position. Form.

As described above, there is provided a processing apparatus that allows the ceramic green sheet 1 and the resin film 2 mounted on the back surface thereof to penetrate the ceramic green sheet 1 and not penetrate the resin film 2 by using the laser beam. The obtained and high quality via hole 3 can be machined.

Embodiment 2 FIG. FIG. 2 is a schematic configuration diagram showing a second embodiment according to the present invention, and 1 to 5 are the same as those in FIG. Processing is performed using the input unit 10, the control unit 20, and the laser unit 30 in FIG. 1, but the following operation is realized by a program different from that in the first embodiment. A resin film 2 is attached to the back surface of the green sheet 1 and is vacuum-adsorbed and fixed by a suction hole 5 provided in a processing table 4 to process a via hole 3 having a hole diameter of 100 μm or less.

The ceramic green sheet 1 is supported on one side by a resin carrier film 2 and is fixed by suction to a processing table 4 having a vacuum suction hole 5, and is irradiated with laser light from the ceramic green sheet 1 side to melt the irradiated portion. The via holes 3 having a desired hole diameter are formed by vaporization.

Here, as the ceramic green sheet 1, a glass-ceramic substrate material having a high glass component content was used. Alumina as ceramic aggregate,
The borosilicate glass as a glass as a main component, Al ₂ O ₃ 35~55% by _{weight, SiO 2 22~35%, B 2} O 3
5-10%, PbO 5-10%, Na as an additive,
A ceramic green sheet material containing 3 to 10% of K, Ca, Ti and Zr and 15% as a binder and an organic solvent was formed on the upper surface of the resin carrier film 2 to a predetermined thickness, for example, 100 μm to 300 μm.

The resin carrier film 2 assists the mechanical strength when the ceramic green sheet 1 is formed, and it is suitable that it has a high laser absorptivity and instantaneous vaporization. Here, a polyethylene terephthalate (PET) film having a thickness of 200 μm to 400 μm was used.

In order to form a straight and high-quality hole with a high aspect ratio, the processing conditions of the laser processing apparatus are as follows:
Normally, the peak power of the pulse laser is increased, and one irradiation time is shortened to irradiate a plurality of shots of laser pulses, and a predetermined number of shots of laser light corresponding to the thickness of the workpiece are irradiated.

Attention is paid to the phenomenon that the inner wall of a non-penetrated green sheet, which has a small number of laser irradiation shots, has a relatively small amount of molten deposits, but a large amount of molten deposits is generated on the inner wall of the hole when the hole is completely penetrated. However, the explosive ejection power due to the vaporization and expansion of the organic matter by the laser in the unpenetrated hole,
It was found that there was a phenomenon of cleaning the molten deposit on the inner wall of the hole.

The mechanism of the generation of the molten deposit on the inner wall of the through hole is as follows. When the laser is irradiated, the alumina particles and glass particles are melted, but the resin binder is instantaneously vaporized, and the explosive vapor expansion causes the molten component to be ejected above the opening.

However, when the hole penetrates, there is no vaporized material, so that the molten material is not jetted out but remains on the inner wall of the hole, cools down, and adheres in a granular form.

Further, in the vicinity of the laser irradiation part, components having a low melting point are easily melted by heat transfer to the periphery, and seep out to the inner wall. This is why ceramic green sheets having a large amount of glass components have a large amount of molten deposits.

In order to make effective use of the output of the vaporized organic substance, the resin film mounted on the back surface of the ceramic green sheet must have a resin thickness sufficient to obtain a sufficient ejection power. What is necessary is just to set the laser irradiation conditions which do not penetrate a film.

However, when the backside resin film penetrates, the vaporizing jet output does not work in the direction of the inner wall of the green sheet but works in the direction of penetration of the backside of the resin film, so that the cleaning power is drastically reduced.

Here, the thickness of the ceramic green sheet 1 is 300 μm, the diameter of the processing hole 3 is 100 μm, the hole pitch is 1 mm, and the resin film 2 is 400 μm thick.
Table 1 shows holes with 121 holes (11 rows x 11 columns).
The drilling data was collected under the processing conditions shown in (1).

Here, the pulse frequency used was a cycle shot method in which a plurality of holes were sequentially irradiated with laser one shot at a time instead of continuous shots one by one.

[0036]

[Table 1]

Under the condition that the pulse width was 40 μs, the resin film was completely penetrated at the fourth shot, and adhesion of the molten material was confirmed on the inner wall. Table 1. In the processing condition setting example, the condition 2 is one in which the pulse energy is kept constant and the pulse width is changed. Under condition 2, the resin film did not penetrate even at the sixth shot, and there was no melt on the inner wall from the fifth shot. The conditions 1 and 3 are constant pulse widths and varied pulse energies.

In this comparison, the number of shots until the ceramic green sheet penetrates is as follows: Condition 1 is the fifth shot and Condition 3 is the fourth shot. Was. In condition 1, a slight amount of melt adhered even at the eighth shot, whereas in condition 3, a via hole for the sixth shot having no adhered melt was obtained on the inner wall.

Further, under the condition 3, the processing hole is not vertical,
It was processed into a conical shape with the center at the top. It was confirmed that the vaporization of the resin film was more easily ejected upward, and at the same time, the resin film was less likely to penetrate, so that cleaning could be performed more stably.

Here, as a comparison condition, the thickness of the resin film 2 was set to 70 μm, and a pulse laser was irradiated under the same processing conditions as in the condition 3. The ceramic green sheet penetrated in four shots, and the resin film 2 having a thickness of 70 μm penetrated simultaneously. Melt adhered to the inner wall of the via hole,
Thereafter, as the number of shots was increased, the amount of the adhered melt on the inner wall increased. On the other hand, condition 3 of resin film thickness 400 μm
Did not completely penetrate up to 8 shots, and the amount of adhered melt on the inner wall decreased as the number of shots was increased.

Also, under the laser irradiation condition of condition 3, when the number of shots was such that the ceramic green sheet only penetrated, the via hole diameter had a tapered shape in which the upper portion was large and the lower portion was small.

In the embodiment shown in Table 1, by repeating the laser irradiation for the number of shots that do not penetrate the resin film even after the green sheet penetrates, not only the inner wall is not melt-adhered but also the taper of the via hole hole as it is. Has been improved and the verticality has been improved. Table 2 shows an example of the number of shots and the perpendicularity of the processed hole.

[0043]

[Table 2]

In the example shown in Table 2, almost vertical via hole holes 3 were formed in eight shots, and a hole having a high aspect ratio with no molten deposit was able to be formed.

According to this method, it is possible to stably form a hole for a via hole in a ceramic green sheet containing a large amount of glass components by laser processing, and in particular, a high aspect ratio.
With respect to (2 or more) via hole processing, a hole free of deposits on the inner wall can be obtained.

There is also a method of improving the material of the ceramic green sheet. However, a change in the composition or composition of the sheet has an effect on the whole, such as a need to reconsider the application to the post-process established conventionally. However, according to the present invention, the above problem can be avoided without considering the material of the ceramic green sheet.

Embodiment 3 FIG. 3 is a schematic configuration diagram showing a third embodiment according to the present invention, and 1 to 5 are the same as those in FIG. Processing is performed using the input unit 10, the control unit 20, and the laser unit 30 in FIG. 1, but the following operation is realized by a program different from that in the first embodiment.

The control unit 20 determines that the processing depth L processed by one-shot laser irradiation is the thickness t of the resin film 2a.
A laser processing apparatus capable of setting a laser beam irradiation condition of the laser unit so as to be に な る or less. In this embodiment, the configuration is the same as that of the first embodiment (FIG. 2) except for the resin film 2a.

The resin film 2a is a resin completely vaporized by the laser used, and has a thickness t which is at least twice the processing depth L at which the resin carrier film 2a is processed by at least one laser irradiation. For example, when the through hole 3 having a hole diameter of 100 μm is formed in the ceramic green sheet 1 having a thickness of 300 μm using the laser of the first embodiment, the thickness of the resin carrier film 2 a is at least 200 μm or more.

At the fourth shot under the conditions 2 and 3 in Table 1, the ceramic green sheet 1 penetrated, and the resin film was partially vaporized to have a concave shape, but did not penetrate. However, a molten deposit on the inner wall of the via hole was confirmed.

Here, the processing depth L processed by one shot of laser irradiation is 1/1 / th of the thickness t of the resin film 2a.
Even if one shot is irradiated, the resin film does not penetrate so that it becomes 2 or less, and the inner wall can be cleaned by ejecting the vaporized material upward. In condition 2 of Table 1, 5
At the shot, the molten deposit was removed.

By improving the resin film 2 to provide a resin film 2a corresponding to the optimum conditions of laser irradiation,
A high aspect ratio via hole for a ceramic green sheet containing a large amount of glass components could be formed without any molten deposits. It is necessary that the resin film absorbs laser energy easily and does not penetrate by one-shot pulsed laser irradiation. As a result of various studies, it has been found that the optimum thickness is at least twice the processing depth processed by one shot of laser irradiation.

As described above, laser irradiation is performed with the number of pulse shots that does not penetrate the carrier sheet 2 on the back surface of the ceramic green sheet 1.
May be a laser processing apparatus using at least one or more conditions under the three conditions that an auxiliary workpiece is added with a sufficient thickness.

In the above, the description has been given of the case where the carbon dioxide laser beam is used. However, the present invention is not limited to the carbon dioxide laser. A processing device may be used.

Embodiment 4 FIG. 4 is a schematic configuration diagram showing a fourth embodiment according to the present invention, in which 7 is an auxiliary film, and 1 to 5 are the same as those in FIG. Processing is performed using the input unit 10, the control unit 20, and the laser unit 30 in FIG. 1, but the following operation is realized by a program different from that in the first embodiment. As a resin film, a resin auxiliary film 7 was mounted on the back surface of the resin carrier film 2b holding the ceramic green sheet 1. The green sheet 1 with the resin film was sucked and fixed by the suction hole 5 provided in the processing table 4 to form a via hole.

The resin auxiliary film 7 is a resin which is completely vaporized by laser irradiation. The thickness t is at least twice the processing depth L at which the resin carrier film 2a is processed by at least one shot of laser irradiation. For example, when forming a via hole hole 3 having a hole diameter of 100 μm on a ceramic green sheet thickness of 300 μm, an auxiliary film made of polyvinyl chloride having a thickness of 200 μm or more was used.

In order to sufficiently exert the cleaning effect of the resin-made auxiliary film 7, it is necessary to apply a uniform force with a constant force using a rubber roller or the like so as to prevent air bubbles from being mixed with the resin-made carrier film 2b. There is.

In this embodiment, a resin carrier film 2 conventionally used as a resin film according to the third embodiment in the previous embodiment 2 (FIG. 2), and a resin auxiliary film 7 is attached. Therefore, it has the same method and effect as those of the second and third embodiments.

On the suction hole provided in the processing table, when the via hole penetrates, the vaporized material is ejected upward and downward, so that the ejection power is further reduced, the amount of adhered molten material is increased, and the quality is reduced. It was not stable. According to the present invention, since the resin film does not penetrate, the above problem can be avoided and stable hole quality can be obtained.

[0060]

As described above, it is possible to stably process a via hole for a ceramic green sheet.
In particular, it is possible to obtain a stable quality without deposits on the inner wall when processing a via hole with a high aspect ratio.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a first embodiment according to the present invention.

FIG. 2 is a schematic configuration diagram showing a second embodiment according to the present invention.

FIG. 3 is a schematic configuration diagram showing a third embodiment according to the present invention.

FIG. 4 is a schematic configuration diagram showing a fourth embodiment according to the present invention.

FIG. 5 is a schematic configuration diagram showing a processing mode according to a conventional method.

FIG. 6 is an operation explanatory diagram in the embodiment shown in FIG. 5;

[Explanation of symbols]

1 ceramic green sheet, 2 resin film,
2a Resin film of second embodiment, 2b Carrier film made of resin, 3 Hole for via hole, 4 Processing table, 5 Suction hole, 6 Attached matter, 7 Auxiliary film, 10 input section, 20 Control section, 30 Laser unit section

Claims (10)

[Claims] 1. An auxiliary workpiece is superimposed on a back surface of a workpiece,
In a laser processing apparatus that forms a through hole in a workpiece, a laser unit that emits a laser beam, an input unit that inputs a material, a plate thickness, a hole diameter, and a plurality of hole positions of the auxiliary workpiece, and the input unit And a controller configured to control the laser unit based on the data input to the workpiece and form a through hole in the workpiece without penetrating the auxiliary workpiece. 2. The laser processing apparatus according to claim 1, wherein the workpiece is a ceramic green sheet. 3. The input unit receives the thickness of the workpiece, and the control unit changes the number of shots of the laser beam at the time of forming each through-hole according to the thickness of the workpiece. The laser processing apparatus according to claim 2, wherein the laser unit is controlled so as to perform the operation. 4. The control unit according to claim 1, wherein a processing depth processed by one-shot laser irradiation is one of the thickness of the auxiliary workpiece.
3. The laser processing apparatus according to claim 2, wherein the irradiation condition of the laser light of the laser unit can be set to be equal to or less than / 2. 5. The laser unit according to claim 1, wherein the laser unit outputs at least one laser irradiation light of a carbon dioxide gas laser beam, a YAG laser beam, and an excimer laser beam. Laser processing equipment. 6. An auxiliary workpiece is superimposed on the back surface of the workpiece,
In a laser processing method for forming a through hole in a workpiece,
A laser processing method, wherein a shot pulse laser beam is emitted from a laser unit, and the auxiliary workpiece is partially vaporized without penetrating the workpiece to form a through hole in the workpiece. 7. The laser processing method according to claim 6, wherein the auxiliary workpiece is a resin carrier film. 8. The laser processing method according to claim 6, wherein the object to be processed is a ceramic green sheet having a resin carrier film attached to the back surface, and the auxiliary object is an auxiliary resin film. 9. The resin auxiliary film is made of polyethylene terephthalate (PET), vinyl chloride (PV).
9. The laser processing method according to claim 8, comprising one or more of C), polyethylene (PE), and acrylic resin. 10. When forming each through hole, a plurality of shots are irradiated with a laser beam, and a time interval between each shot is set to be at least solidified after the point to be processed is melted. The laser processing method according to claim 6.