JP2000263264A - Laser beam machining method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form nozzle openings of an uniform size and shape on a film for a nozzle plate. SOLUTION: A laser beam machining method in which laser beam converged with an optical system is irradiated to form nozzle openings 32 on a film 30 for a nozzle plate held on a table 14 has a step to detect the temp. of a machining environment and a step to machine while correcting the relative position between the focus position of a laser beam and a table surface on the basis of the detected temp. Consequently, uniform nozzle openings are formed to the film 30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser processing method using a laser beam, and more particularly, to a nozzle plate film constituting an ink jet type recording head which is applied to a printer, a facsimile and the like using an excimer laser. The present invention relates to a laser processing method for forming a nozzle opening.

[0002]

2. Description of the Related Art Conventionally, when a workpiece such as a substrate is precision-processed on the order of μm, for example, when a hole is formed, the workpiece is processed by irradiating a laser beam such as an excimer laser. Laser processing machines are used.
In particular, a laser processing machine with high processing accuracy is generally used for a hole serving as a nozzle opening for discharging ink of an ink jet recording head since the processing state of the hole greatly affects ink characteristics.

In such a laser beam machine 100, FIG.
As shown in FIG.
It is held by a chucking table 102 provided on an XYZ table 101 that can be moved in the dimensional direction. Then, a laser beam L oscillated from a laser oscillator (not shown) is converged by an optical system 105 including a converging lens 104 and the like held in a housing 103 and is irradiated on the surface of the film 110 to form a through hole 111. You.

As described above, when a nozzle plate is formed on a film for a nozzle plate by using a laser processing machine, for example, a polyimide sheet or the like having a thickness of about 50 μm is generally used for the nozzle plate. Is formed from the irradiation side surface to the back surface. In this case, since the diameter of the tapered hole, the angle of the taper, and the like need to be uniformed with high precision, the energy density, focus, and the like of the laser beam must be controlled with high precision.

[0005] Therefore, it is necessary to always measure the energy density of the irradiated laser light, and to feedback-control the aperture of the laser oscillation device based on this to obtain a laser light having a constant energy density.

[0006]

However, even if the focal position of the laser beam is once adjusted with high precision, there is a problem that the shape, size, and the like of the through hole 105 actually formed vary. There is. Further, as described above, when the nozzle openings are formed in the nozzle plate film, the variation directly affects the ink ejection performance, and therefore it is desirable to form the nozzle openings as uniformly as possible.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a laser processing method capable of forming a nozzle opening having a uniform size and shape in a nozzle plate film.

[0008]

According to a first aspect of the present invention, there is provided a laser for irradiating a laser beam focused by an optical system to form a nozzle opening in a nozzle plate film held on a table. A laser processing method comprising: a step of detecting a temperature of a processing atmosphere; and a step of performing processing while correcting a relative position between a focal position of the laser beam and the table surface based on the detected temperature. In the way.

A second aspect of the present invention is the laser processing method according to the first aspect, wherein the processing atmosphere temperature is a temperature near a device having the optical system. A third aspect of the present invention is the laser processing method according to the first or second aspect, wherein the laser beam is an excimer laser. The present invention has been completed based on a new finding that the variation in processing the nozzle openings is caused by a change in the temperature of the processing atmosphere.

In the present invention, a plurality of nozzle openings are formed in a uniform shape and size in a film for a nozzle plate constituting an ink jet recording head.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments of the present invention. FIG. 1 is a schematic diagram of a laser processing machine according to one embodiment of the present invention. As shown in FIG. 1, a laser processing machine 10 according to the present embodiment is a device for forming a nozzle opening for discharging ink on a film 30 for a nozzle plate constituting an ink jet recording head. A laser oscillator 11 that oscillates a laser beam such as a laser, a holding movable section 12 that holds a film 30 processed by the laser beam and is movable in a three-dimensional direction, and a laser beam oscillated from the laser oscillator 11 And an optical system 13 arranged to irradiate the surface perpendicularly.

The holding movable section 12 includes a chucking table 14 for sucking and holding the film 30, and X, Y, and X, which move the chucking table 14 in three-dimensional directions.
Z tables 15, 16 and 17. Although not shown, these tables 15, 16, 17 are controlled by control means provided in the laser beam machine 10.

The optical system 13 includes an attenuator 18, a homogenizer 19, a mask 20, and a wobble unit 21.
And a converging lens 23 held by a housing 22, which are sequentially arranged from the laser oscillator 11 side to the film 30. The laser light oscillated by the laser oscillator 11 is rectangular and has an energy distribution with a large energy density at the center, but the attenuator 18
This reduces the total amount of laser light to an appropriate level, and the laser light after passing through the attenuator 18 has a similar energy distribution.

The homogenizer 19 is for homogenizing the horizontal and vertical energy distributions of the laser beam. For example, the homogenizer 19 homogenizes the horizontal energy distribution in the first stage and the vertical energy distribution in the second stage. Uniform energy distribution. The mask 20 is for cutting a rectangular laser beam into a predetermined size and shape, and has a predetermined size and shape, for example, as shown in FIG. A plurality of through-holes 21a having a diameter about three times as large as that of FIG.

The wobble unit 21 adjusts the energy distribution of the laser beam in the radial direction. As shown in FIG. 3, the wobble unit 21 is rotatably held with the translucent plate 21a inclined at a predetermined angle. I have. That is, after passing through such a wobble unit 21, the high-density region L ₁ in which the laser beam is always irradiated intermittently with low-density regions L ₂ occurs irradiated, the energy density in the radial direction of the laser beam L Differences occur. The rate of change in the energy density in the radial direction changes depending on the inclination angle of the transmissive plate 21a. For example, as shown in FIG.
If you decrease the inclination angle of the 1a, the proportion is relatively large in the high-density region L ₁ of the central portion is small low-density regions L ₂ of the surrounding. On the other hand, as shown in FIG. 3 (b), when increasing the inclination angle of the plate 21a has a small proportion of high-density regions L ₁ of the central portion, the low-density region L ₂ of the surrounding
Is big. Thus, by changing the inclination angle of the plate 21a, it is possible to substantially adjust the average energy density of the entire laser beam L. Thereby, the energy density can be adjusted to an appropriate size.

For example, the film 30 is irradiated with laser light.
When a nozzle opening is formed, the taper angle of the through hole is usually changed by changing the energy density. For example, it is necessary to stabilize the energy density to about 1 J / cm ^2. The energy density of the laser light is not stable. However, by using the wobble unit as described above, the energy density of the laser beam can be substantially stabilized.

The focusing lens 2 held by the housing 22
Numeral 3 is for focusing the laser beam at a predetermined position. Note that the focusing lens 2 is actually provided in the housing 22.
A plurality of lenses (not shown) including the lens 3 are held, and the laser beam is focused at a predetermined position via the plurality of lenses. In the present embodiment, the nozzle opening is formed in the film 30 for the nozzle plate by using such a laser processing machine 10. At this time, the temperature in the vicinity of the laser irradiation part where the laser light is irradiated at a predetermined time is measured. Then, the deviation of the focal position of the laser beam is corrected based on the measurement result, and the shape and size of each nozzle opening are made uniform.

For this reason, in the present embodiment, as shown in FIG. 4, a temperature sensor 40 for measuring the temperature near the processing section 31 is provided near the housing 22 holding the focusing lens 23 and the like. The temperature sensor 40 is connected to a control means 45 for controlling the XYZ tables 15, 16, 17 and the measurement result is sent to the control means 45. Then, the control means 45 corrects the shift of the focal position of the laser beam by moving the Z table 17 to a predetermined position by performing feedback control based on the measurement result. Hereinafter, an example of a process of forming a nozzle plate using such a method will be described.

As shown in FIG. 5, the nozzle plate 35 is formed of, for example, a film 30 of polyimide or the like. The nozzle plate is divided at each position. FIG. 6 is a schematic view showing the vicinity of a laser irradiation part of a laser processing machine. First, as shown in FIG. 6A, a first processing in which a nozzle opening 32 is first formed at a predetermined location, for example, at the portion corresponding to the part 31A, the distance between the focal position and the film 30 of the surface of the laser beam to adjust the height of the film 30 so that h _1. At the same time, the first temperature is detected by the temperature sensor 40.
The temperature in the vicinity of the processed part 31A is measured, and this is set as a reference temperature.

When the film 30 is irradiated with a laser beam to form the nozzle opening 32, the first processing portion 31 is again formed.
The temperature near A is measured, and the measurement results are sent to the control means 45 for controlling the XYZ table. The control means 45 controls the Z table 17 based on the measurement result of the temperature sensor 40 to move the Z table 17 to a predetermined position. That is, the correction is performed by the correction amount based on the correction table of the temperature difference between the measured temperature and the reference temperature and the deviation amount of the focal position of the laser beam.

Here, the relationship between the temperature change and the shift amount of the focal position of the laser beam is measured in advance. For example, in the laser beam machine 10 of the present embodiment, each time the temperature rises once, the focal position shifts upward by 12 μm. However, since this ratio is a value unique to the device that changes due to various effects, it is necessary to measure the ratio in advance for each device. Then, as shown in FIG. 6B, the XYZ table 15,
16 and 17 are controlled by the control means 45, and move so that the second processing portion 31B becomes the irradiation position of the laser beam L. At this time, the focus position P ₂ of the laser beam, although deviated upward from the focus position P ₁ by d, the position of the Z table 17 is corrected by d, the focus position P ₂ and the film 30 of the laser beam the distance between the surface of is kept constant and h _1. Then, a second nozzle opening 32B is irradiated with a laser beam L at the irradiation position P _2. At this time, similarly to the case of the first processing unit 31A, the temperature sensor 4
Based on 0, the temperature near the second processing portion 31B is measured.

Thereafter, as described above, when the XYZ table is moved, the Z table is controlled based on the measurement result of the temperature sensor 40 to correct the focal position of the laser beam, and the laser beam is uniformly moved to a predetermined position. The nozzle opening 32 having an appropriate shape and size is formed. After that, the film 30 in which all the nozzle openings 32 are formed is divided at a predetermined position to form a nozzle plate 35.

As described above, in the present embodiment, each processing unit 3
1 is measured and the Z table 1 is determined from the measurement result.
7 is feedback-controlled to correct the deviation of the focal position of the laser beam L. Thereby, the distance between the focal position of the laser beam and the surface of the film 30 can be always kept constant. That is, the laser beam can be irradiated under the same conditions in each of the processing sections 31, and the nozzle openings 32 having a uniform shape and size can be formed in each of the processing sections 31.

In this embodiment, the shift of the focal position of the laser light with respect to the film is corrected by moving the Z table. However, the present invention is not limited to this. May be adjusted. It goes without saying that these may be combined. Further, in the present embodiment, the temperature in the vicinity of the processing portion is measured every time the processing position is changed. However, the present invention is not limited to this. For example, the temperature may be constantly measured. During the formation of the nozzle opening in the film by the light, the deviation of the irradiation position of the laser light may be appropriately adjusted.

Here, an example of a head chip using the nozzle plate formed as described above will be described. FIG.
1 is an exploded perspective view of a head chip according to an embodiment of the present invention. As shown in FIG. 7, a plurality of grooves 52 are provided in the piezoelectric ceramic plate 51 in parallel, and each groove 52 is separated by a side wall 53. One end in the longitudinal direction of each groove 52 extends to one end surface of the piezoelectric ceramic plate 51, and the other end does not extend to the other end surface, but gradually decreases in depth. Further, electrodes 54 for applying a driving electric field are formed on the opening side surfaces of both side walls 53 in each groove 52 in the longitudinal direction.

Here, each groove 52 formed in the piezoelectric ceramic plate 51 is formed by, for example, a disk-shaped die cutter, and a portion whose depth is gradually reduced is formed by using the shape of the die cutter. Is done. In addition, each groove 5
The electrode 54 formed in 2 is formed by, for example, a known oblique evaporation. An ink chamber plate 55 is joined to the opening side of the groove 52 of the piezoelectric ceramic plate 51. In the ink chamber plate 55,
The ink chamber 56 has a recess communicating with the shallow other end of each groove 52, and an ink supply port 57 penetrating from the bottom of the ink chamber 56 in a direction opposite to the groove 52.

The nozzle plate 35 is joined to the end face of the joined body of the piezoelectric ceramic plate 51 and the ink chamber plate 55 where the groove 52 is open, and the nozzle plate 35 is located at a position facing each groove 52 of the nozzle plate 35. Is formed with the nozzle opening 32 formed as described above. Further, the piezoelectric ceramic plate 51 and the ink chamber plate 5
Around the end of the joint 52 with which the groove 52 is open,
A nozzle support plate 58 is provided. The nozzle support plate 58 is joined to the outside of the end face of the joined body of the nozzle plate 35 to stably hold the nozzle plate 35.

[0028]

As described above, according to the present invention, when forming a nozzle opening in a film for a nozzle plate by using a laser processing machine, a temperature change in each processed portion of the film is detected, and the detection result is obtained. The Z-table is controlled based on the correction of the shift of the focal position of the laser light with respect to the film. As a result, the distance between the focal position of the laser beam and the surface of the film is always constant, and there is an effect that a nozzle opening having a uniform shape and size can be formed in each processing portion.

[Brief description of the drawings]

FIG. 1 is a schematic view of a laser processing machine according to an embodiment of the present invention.

FIG. 2 is a perspective view illustrating a mask used in the laser beam machine according to the embodiment.

FIG. 3 is a schematic diagram illustrating a wobble unit used in the laser beam machine according to the embodiment.

FIG. 4 is a perspective view illustrating a nozzle plate according to an embodiment of the present invention.

FIG. 5 is a schematic view showing a main part of a laser processing machine according to one embodiment of the present invention.

FIG. 6 is a schematic diagram illustrating a process of forming a nozzle plate according to the present embodiment.

FIG. 7 is an exploded perspective view of a head chip according to an embodiment of the present invention.

FIG. 8 is a schematic view showing a main part of a laser beam machine according to the related art.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 laser processing machine 11 laser oscillator 12 holding movable section 13 optical system 14 chucking table 15 X table 16 Y table 17 Z table 18 attenuator 19 homogenizer 20 mask 21 wobble unit 22 housing 23 focusing lens 30 film 31 processing section 32 nozzle opening 35 nozzle plate 40 temperature sensor 45 control means

Claims (3)

[Claims] 1. A laser processing method for irradiating a laser beam focused by an optical system to form a nozzle opening in a film for a nozzle plate held on a table, wherein the step of detecting a temperature of a processing atmosphere is performed based on the detected temperature. And correcting the relative position between the focal position of the laser beam and the surface of the table. 2. The laser processing method according to claim 1, wherein the processing atmosphere temperature is a temperature near an apparatus having the optical system. 3. The laser processing method according to claim 1, wherein the laser beam is an excimer laser.