JPH0994964A - Manufacture of ink jet head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the damage of a channel board and to perform the high efficiency of processing by eliminating mechanical polishing step without forming a shallow groove. SOLUTION: After a plurality of groove-like ink channels 2 are engraved on the upper surface of a channel board 1 made of a piezoelectric material, metal is vacuum-deposited from above, and metal films are formed on the upper surface (channel engraved surface) of the board 1 including the upper end face of a partition wall 8 and the upper part of the side of the wall 8. Then, the metal film is separated at each channel 2 by irradiation with laser, and electrodes 6 and electrode connectors 7 are formed. Thus, a cover plate is connected to the upper surface of the board 1 formed in this manner and a nozzle plate is connected to the front end face.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for manufacturing an inkjet head.

[0002]

2. Description of the Related Art Conventionally, there has been a structure in which an ink flow path is formed in a flow path substrate of which at least a part is made of a piezoelectric material in an ink jet head. This is one in which a partition wall section that divides the ink flow path is made of a piezoelectric material, and electrodes made of a metal film are formed on both surfaces of this partition wall. When an electric field is applied to this electrode according to the print signal,
The partition wall is piezoelectrically deformed to change the volume of the ink flow path, and the ink in the ink flow path whose volume has been reduced receives pressure and is ejected.

When manufacturing such an ink jet head, as shown in FIG. 11, first, a plurality of parallel groove-shaped ink flow paths 21 and a shallow groove portion 23 continuous with the flow path substrate 20 made of a piezoelectric material. After the engraving, a metal film is formed on the engraved surface of the channel and on the upper side surface of the partition wall 22 by vapor deposition or the like from above the engraved surface of the channel substrate. In this state,
The metal films on the side walls of each partition wall are short-circuited on the engraved surface of the flow path and the upper surface of the partition wall, and the partition wall can be freely deformed by selectively conducting only the metal film (electrode) corresponding to any ink flow path. I can't. Therefore, usually, the engraved surface of the flow path and the upper end surface of the partition wall are mechanically polished to remove the metal film at this portion to form separate electrodes for each flow path. Then, a cover plate is attached to the upper surface of the flow path substrate. As shown in FIG. 11, the ink channel 2 of the channel substrate 20 is
The rear end portion 1 is formed so as to be gradually shallower and communicates with the shallow groove portion 23, and a metal film is formed on the side surface of the partition wall 22 in a portion where the depth of the ink flow channel is deep. Is filled with metal so as to spread in a plane and fill the inside of the groove due to the shallowness of the groove. This is an electrode connection portion where wire bonding and the like are performed.

[0004]

As described above, conventionally, the metal film is separated by polishing in order to obtain an independent (non-short-circuit) electrode for each flow path. Damage such as chipping may occur, which causes a decrease in yield. Further, in order to provide the electrode connection portion, a shallow groove portion is formed in the ink flow path, and the metal film in the shallow groove portion is left after polishing, but since the shallow groove portion is formed, the processing speed is slow. A cutting process is required and processing time is long.

In the wire bonding process, it is necessary to bring the tip of the bonding tool into contact with the lower surface of the shallow groove portion, and therefore it is desirable that the shallow groove portion is shallow in order to improve reliability (the shallow groove portion is too deep. Since the bonding tool hits the side wall of the shallow groove and cannot contact the lower surface, specifically, a depth of 15 μm or less is desirable). on the other hand,
If the shallow groove portion is too shallow, the metal film in the shallow groove portion may also be removed during polishing. Therefore, the shallow groove portion must be formed extremely accurately, but it is difficult to keep the shallow groove portion at a desired depth constant due to the influence of the thickness and the flatness of the substrate made of a piezoelectric material. Such defects were likely to occur. Further, since the bottom surface of the shallow groove portion is a machined surface, it is rough and has a low adhesion strength to the metal film, and the metal film may be peeled off during bonding. Further, relative positional accuracy between the ink flow path and the shallow groove portion is also required.

Therefore, an object of the present invention is to provide a method for manufacturing an ink jet head which can achieve a yield improvement, a processing time reduction, and a bonding work simplification by eliminating a mechanical polishing step without forming a shallow groove portion. It is in.

[0007]

In order to achieve the above object, the present invention provides a flow channel substrate having an ink flow channel engraved therein,
An ink jet head having a cover plate fixed on the engraved surface of the flow path substrate, and ejecting ink in the ink flow path by applying an electric field to the side wall of the partition wall that partitions the ink flow path to cause piezoelectric deformation. In the manufacturing method of, a plurality of parallel groove-shaped ink channels are engraved on a channel substrate at least a part of which is formed of a piezoelectric material, and the channel engraved surface of the channel substrate and the partition wall upper end surface and upper side surface are formed. The method is characterized by including a step of forming a metal film and separating the metal film for each ink flow path by laser irradiation on the flow path engraved surface of the flow path substrate and the partition wall upper end surface.

[0008]

FIG. 1 is a perspective view showing a completed state of an ink jet head according to the present invention. The structure is such that a plurality of groove-shaped ink flow paths 2 are provided on the upper surface of a flow path substrate 1 made of PZT which is a piezoelectric material, and a cover plate 3 is bonded to the flow path contact surface (upper surface). The nozzle plate 4 is joined to the end surface of the path substrate, and the open end of each ink flow path 2 and the nozzle 5 formed in the nozzle plate communicate with each other. An electrode 6 is formed on a partition wall 8 that partitions each ink flow path 2 of the flow path substrate 1, and the ink flow path is gradually shallowed in the rear part of the flow path substrate, and an electrode connecting portion 7 continuous from the electrode 6 is formed. Is provided. The electrode 6 and the electrode connecting portion 7 are separated for each ink flow path 2.
A window hole 3a is formed in the rear portion of the cover plate 3, and the rear end portions 2a of all the ink flow paths 2 are exposed through the window hole 3a. Although not shown, a manifold having a common ink chamber for supplying ink to all the ink flow paths 2 is joined to the window 3a. Then, the driving power is connected to a driver substrate (not shown) and is selectively supplied to any of the electrode connecting portions 7, and is supplied to the electrodes 6 on the side surfaces of the partition walls 8 that partition the ink flow path 2. Due to this, the volume of the ink flow path 2 is reduced and the ink inside is ejected from the nozzle 5 to the outside.

A method of manufacturing the above ink jet head will be described below. First, as shown in FIG. 2, a plurality of groove-shaped ink channels 2 are formed on the upper surface of a channel substrate 1 made of a piezoelectric material by cutting using a dicing saw or the like. The pitch of the ink flow paths 2 is set to be the same as the desired nozzle pitch, and the rear end of the ink flow paths 2 is formed in an arc shape corresponding to the outer circumference of the circular dicing saw, as shown in FIG. Shallow groove 23 as in the conventional example
Is not provided.

Therefore, as shown in FIG. 3, a metal such as Al or Ni is vacuum-deposited from above the flow path substrate 1 to form the partition wall 8.
The metal film 9 is formed on the upper surface of the flow path substrate 1 including the upper end surface and the upper portions of the side surfaces of the partition walls 8. It should be noted that the metal film is not formed on the lower portion of the side surface of the partition wall 8 by performing vapor deposition once on the partition wall 8 in the diagonal direction and once on the right and left sides.

Next, an excimer laser is irradiated from above the flow path substrate 1 to partially remove the metal film 9 by the laser ablation effect as shown in FIG.
Are separated for each ink flow path to separate the electrode 6 and the electrode connecting portion 7.
Is configured. A supplementary description of this laser ablation effect is a method of irradiating an object with a high-energy ultraviolet laser pulse to break an intermolecular bond to decompose and remove the object. The decomposition depth per shot can be adjusted by adjusting the pulse energy density incident on the object. Here, the irradiation width of the excimer laser was set to be narrower than the width of the upper end surface of the partition wall 8, and the Ni film of 2 μm could be removed within 5 shots at the pulse energy density of 640 mJ / cm ² .

The ink jet head shown in FIG. 1 is completed by joining the above-mentioned cover plate 2 and nozzle plate 3 to the flow path substrate 1 manufactured as described above. According to this, the step of mechanically polishing the engraved surface of the flow path substrate 1 is not required, so that there is no risk of damaging the partition wall 8. Further, since the shallow groove portion forming step, which has conventionally required a precise work, is not required, the work is simplified and the processing time is shortened. Since the metal film is provided on the smooth flow path substrate instead of the shallow groove portion to form the electrode connection portion, peeling is unlikely to occur, reliability is high, and work such as bonding is easy and reliable.

A second example of the step of separating the metal film 9 by laser irradiation will be described with reference to FIGS. In this example, a mask 10 having a shielding portion 10a for protecting the portion where the metal film 9 is to be left from the laser is used. That is, laser irradiation (in the direction of the arrow) is performed with the mask 10 placed or brought close to the flow path substrate 1 in the state shown in FIG. 3 in which the metal film 9 is formed on the flow path engraved surface. Then, the laser is transmitted through the transmitting portion 10b to remove the metal film 9 in that portion, and the metal film 9 remains only in the portion of the shielding portion 10a. As shown in FIG. 6, the electrodes 6 and the electrode connecting portions 7 in a staggered arrangement are formed.
Can be. In this case, it is not necessary to match the laser irradiation width with the width of the upper end surface of the partition wall 8 as in the first example, and if the energy density capable of laser ablation can be secured,
It is possible to irradiate the surface of the mask 10 by expanding the beam shape as much as possible. Then, since the electrode film having a large area can be removed at once, the scanning of the laser beam or the movement of the substrate is unnecessary, and the processing is completed in a smaller number of shots and in a shorter time. Further, as shown in FIG. 6, since the electrode connecting portions can be formed in arbitrary positions and shapes such as a zigzag arrangement, it is easy to cope with high density. In the example shown in FIG. 5, the contact mask method is used in which the mask 10 having the same scale as the pattern to be formed is brought into contact with or close to the flow path substrate 1 to irradiate the laser, but a mask having a different scale is scaled. An imaging mask method of forming an image on the flow path substrate 1 via a lens can also be used.

In the above-mentioned first and second examples, the laser irradiation direction is not particularly limited, but the decomposition efficiency is highest for the plane perpendicular to the laser incident optical axis, and the decomposition efficiency decreases as it is inclined from the incident optical axis. To do. Therefore, it is desirable that the upper surface of the flow path substrate provided with the metal film 9 to be removed is perpendicular to the laser optical axis, and the side surface of the partition wall 8 where the metal film 9 is not to be removed is parallel to the laser optical axis. . Particularly, when the side surface of the partition wall 8 is parallel to the laser optical axis, the metal film 9 on this surface is hardly removed. Therefore, it is necessary to dispose a mask as in the second example on the ink flow path 2. There is no.

A third example is shown in FIGS. In this example, the upper surface of the flow path substrate 1 and the partition wall 8 are provided not vertically but at an angle. The mask 11 arranged on this has the shielding portion 11a only in the portion where the electrode connecting portion is to be formed, and the other portion is the transmitting portion 11b. Then, the laser is irradiated in a direction (arrow direction) parallel to the side surface of the partition wall 8. The laser passes through the ink flow path 2, but the metal film 9 on the side surface of the partition wall 8 is hardly affected. Further, since the laser is incident on the upper surface of the flow path substrate 1 with a tilt, the efficiency is slightly lowered, but the metal film 9 on the upper surface of the flow path substrate 1 is reduced.
Can be removed, and only the metal film 9 facing the shield portion 11a remains. Therefore, as shown in FIG. 10, the flow path substrate 1 having the electrodes 6 and the electrode connecting portions 7 is completed. According to this, the positioning of the mask 11 does not require so much accuracy, and the work becomes easy.

Although the metal film is removed by the excimer laser in the above embodiment, the same processing can be performed by the YAG laser or the CO ₂ gas laser.

[0017]

As described above, according to the present invention, it is possible to prevent the partition walls from being damaged by mechanical polishing of the flow path substrate, and it is not necessary to form a shallow groove portion, which simplifies the work and shortens the processing time. Become. Further, when laser irradiation is performed using a mask, it is possible to remove a wide area of the electrode film in a batch, and thus work efficiency is good. Further, when the laser irradiation is performed in the direction parallel to the side wall of the partition wall, the mask can be simplified and the work can be facilitated while ensuring the electrode on the side surface of the partition wall.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view showing a completed state of an inkjet head.

FIG. 2 is a perspective view showing an ink flow path forming step.

FIG. 3 is a plan view and a front view showing a metal film vapor deposition process.

FIG. 4 is a plan view and a front view of the flow path substrate after the metal film separation step.

FIG. 5 is a front view showing a second example of the metal film separation step.

FIG. 6 is a plan view of a mask used in a second example.

FIG. 7 is a plan view of the flow path substrate after the metal film separation step of the second example.

FIG. 8 is a front view showing a third example of the metal film separation step.

FIG. 9 is a plan view of a mask used in a third example.

FIG. 10 is a plan view and a front view of the flow path substrate after the metal film separation step of the third example.

FIG. 11 is a perspective view showing a conventional ink flow path and shallow groove forming step.

[Explanation of symbols]

 1 flow path substrate 2 ink flow path 3 cover plate 8 partition wall 9 metal film 10, 11 mask

Claims (1)

[Claims] 1. A flow channel substrate having an ink flow channel engraved therein,
A cover plate fixed to the flow path engraving surface of the flow path substrate, and ejecting ink in the ink flow path by applying an electric field to the side wall of the partition wall that partitions the ink flow path to cause piezoelectric deformation In the method of manufacturing an ink jet head according to claim 1, a plurality of parallel groove-shaped ink channels are engraved on the channel substrate, at least a part of which is made of a piezoelectric material, and the channel engraved surface of the channel substrate and the partition wall are And a step of forming a metal film on the end face and the upper part of the side face, and separating the metal film for each ink flow path by laser irradiation on the flow path engraving surface of the flow path substrate and the partition wall upper end surface. Inkjet head manufacturing method.