JP2002127414A - Ink jet recording head and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive ink jet recording head which can be manufactured by an inexpensive manufacturing facility while keeping excellent ink ejection characteristics and reducing the labor required for manufacturing. SOLUTION: An ink channel groove is formed in the channel substrate of a recording head by jetting alumina abrasive grains of 800 mesh using a dry film of 50 μm thick as a mask. When an ink nozzle of 50 μm wide is machined at 40 μm deep (number of times of nozzle path = 8), a depth of 65 μm is attained in an ink pressurization chamber of 2 mm wide and a shallow etching part of ink nozzle can be machined simultaneously with a deep etching part of ink pressurization chamber by the same machining process. A groove formed by jetting abrasive grains has inner surface exhibiting high wettability to ink and no alkaline processing is required for decreasing the contact angle of ink.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording head used in an ink jet recording apparatus for recording by ejecting ink as small droplets from nozzles.

[0002]

2. Description of the Related Art A method of ejecting ink from a minute ink nozzle and attaching the ink to a recording medium such as paper to perform recording is as follows.
It is known as an ink jet recording method. As one type of this method, there is an on-demand type ink jet recording head that performs recording by ejecting ink only to a recording portion.
An ink jet print head of this type (hereinafter, simply referred to as a print head) was manufactured by Mr. Kaiser of the United States in 197.
It was proposed in 2000, and in Japan,
It is published in the 38th publication. Printing apparatuses using such recording heads are widely used in fields such as desktop printers and fax machines that require small size and light weight because of their advantages such as simple structure and low maintenance cost.

As one of the recording heads, a piezoelectric element is bonded to a diaphragm, a pulse voltage is applied to the piezoelectric element to expand and contract the piezoelectric element, and as a result, the diaphragm vibrates to eject ink. There is a recording head of the system.
A piezoelectric recording head generally has a cross-sectional structure shown in FIG. 6, and its ink flow path is configured as shown in FIG. Usually, the flow path substrate 1 is made of a silicon wafer, a glass plate, a metal plate, a plastic material, or the like. In the flow path substrate 1, an ink nozzle 2, a nozzle flow path 3, an ink pressurizing chamber 4, an ink supply path 5, and a throttle flow path (a flow path resistance adjustment unit) are formed by etching, machining, molding, or the like. In FIG. 5, a plurality of ink flow paths 11 including a filter flow path 6 and a common ink reservoir 7 and an ink injection port 12 connected to the plurality of ink flow paths 11 (hereinafter referred to as ink flow path grooves). Is formed. A vibrating plate 8 made of a glass plate, a metal plate, a plastic material or the like is laminated and integrated on the ink flow channel groove side of the flow channel substrate 1 to form an ink flow channel 11 and the like. A piezoelectric element 9, which is an electromechanical transducer, is adhered to an opposite surface of the vibration plate 8 corresponding to the chamber 4 by an adhesive layer 10.

[0006] The piezoelectric element 9 of the recording head having such a configuration is used.
When a pulse-shaped voltage is applied to the piezoelectric element 9, the piezoelectric element 9 is deformed and the diaphragm 8 is bent. When the vibrating plate 8 is rapidly curved toward the ink pressurizing chamber 4 and its volume is rapidly reduced, the ink corresponding to the reduced volume is pushed out to the nozzle flow path 3 and is ejected from the ink nozzle 2. Attached in a dot pattern on a recording medium (not shown), a predetermined recording is executed by the accumulation.

The example shown in FIG. 6 is a case where an ink flow channel is formed on one surface of the flow channel substrate 1. However, a similar groove is also formed on the opposite surface, and the number of nozzles is increased. Often, the pitch of the ink nozzles 2 is narrowed. In some cases, an ink nozzle, an ink injection port, and the like are formed as through holes, and only a part of the ink flow path including the ink pressurizing chamber is formed as a groove.

The market for such a recording head is as follows.
While seeking better ink ejection characteristics, there is also a strong demand for miniaturization, multiple nozzles, low cost, and the like. If plastic is used as the material of the flow path substrate 1, it is possible to reduce the cost by applying an injection molding technique or the like. However, since the elastic modulus of the material is low, there is a limit in increasing the speed of ink ejection and increasing the frequency. It is difficult to obtain a desired printing speed.

If metal is used as the material of the flow path substrate 1, it is difficult to finely process a plurality of ink flow paths,
There are difficulties in dimensional stability of the ink flow path, downsizing of the recording head, and increasing the number of nozzles. When a silicon wafer is used as the material of the flow path substrate 1, photolithography and dry plasma etching technology can be applied, and a plurality of ink flow path grooves can be formed finely and with high dimensional accuracy. There is an advantage. Furthermore, if borosilicate glass is used for the diaphragm 2, it can be integrated with the silicon wafer of the flow path substrate 1 by electrostatic bonding, has high rigidity, and realizes a recording head having excellent ejection characteristics and stability. be able to.

FIG. 4 is a manufacturing process diagram showing a manufacturing process for forming an ink flow channel by photolithography and dry plasma etching using a silicon wafer as a material of the flow channel substrate 1. First, an oxide film having a thickness of about 1 μm is formed on the surface of a mirror-polished silicon wafer (process).
1a), an oxide film is patterned by photolithography according to the shape of the ink flow channel groove (step 2a). An aluminum film having a thickness of about 1 μm is formed on the patterned surface by vacuum deposition or sputtering (step 1b), and the aluminum film is patterned according to the shape of the portion requiring deep engraving such as the ink pressurizing chamber 4 (step 1b). Step 2b). Then, the deep engraved portion is first processed to a predetermined depth by the next dry plasma etching (step 3b) by the dry plasma etching technique using the aluminum film as a mask (step 3).
a). Here, the aluminum film is removed to expose the oxide film patterned into the shape of the ink flow channel (step 4a), and an ink flow channel having a predetermined depth is formed again by the dry plasma etching technique (step 4a). 3b). Finally, the oxide film is removed, and the silicon wafer on which the ink flow channel is formed is washed to complete the flow channel substrate 1 (Step 4).
b).

A borosilicate glass may be used as the material of the flow path substrate 1 and a silicon wafer may be used as the vibration plate 2. However, it is difficult to form fine ink flow grooves in the borosilicate glass with high precision. Since it is more difficult than a silicon wafer, it has not yet reached the stage of practical use.

[0010]

SUMMARY OF THE INVENTION As described above,
The recording head using a silicon wafer as the flow path substrate and a borosilicate glass as the diaphragm has high rigidity, excellent dimensional accuracy,
Although it has the excellent advantage of stable ink ejection characteristics, it uses photolithography and dry plasma etching technology, so manufacturing equipment costs are high,
In addition, the manufacturing process is complicated, requires a long processing time and a large number of manufacturing steps, and as a result, it is difficult to reduce the cost.

An object of the present invention is to make it possible to process an ink flow channel with a less expensive manufacturing facility while reducing the processing time and man-hour required for the processing while keeping the above advantages. And

[0012]

According to the first aspect of the present invention, a groove corresponding to the entire ink passage from the ink supply section to the ink nozzle or at least a part of the ink passage including the ink pressurizing chamber and the ink nozzle is provided. A flow path substrate formed and joined to the groove side of the flow path substrate to cover the groove of the flow path substrate to form an ink passage, and pressurize an ink pressurizing chamber on the surface on the opposite side. And a diaphragm to which the piezoelectric element is bonded, wherein the groove for the ink passage is a groove formed by abrasive grain spraying.

The inventor of the present invention has studied the processing of an ink flow path on a silicon wafer by abrasive grain spraying by changing the grain size of abrasive grains, and it is considered unsuitable from conventional common sense. It has been found that it is possible to form an ink channel by brazing abrasive spraying. As a mask for abrasive spraying, a positive dry film having a thickness of 50 μm, from which a portion corresponding to an ink flow path was removed by photolithography, was used.

FIG. 1 is a diagram showing a part of the result of the study, in which the horizontal axis represents the mask removal width, the vertical axis represents the processing depth, and the number of nozzle passes for abrasive grain injection as a parameter. Things. The processing conditions are as follows. Abrasive grain material: Alumina Abrasive grain size: 800 mesh Injection pressure: 0.25MPa Distance between the ejection nozzle and the wafer surface: 100mm Moving speed of the ejection nozzle: 50mm / sec According to the result of FIG. About 50μm
Eight nozzle passes are required to engrave 40μm. Under these conditions, the ink pressurization chamber with a width of 220μm or more can be processed to a depth of about 65μm, and can be used as it is as an ink pressurization chamber. can do. In addition, it has been found that it has excellent processing accuracy and reproducibility, and is sufficiently practical as a processing means of the ink flow path.

FIG. 2 shows 800 mesh, 1000 mesh, and 12 mesh.
FIG. 9 is a diagram showing a result of examining three types of abrasive grain sizes of 00 mesh by setting the number of nozzle passes to 10 times, using a mask removal width as a parameter. According to this result, the ink nozzle and the ink pressurizing chamber can be simultaneously processed by the same processing only in the case of 800 mesh, and in the case of 1000 mesh and 1200 mesh, the ink nozzle is processed to a predetermined depth. However, in such a state, the depth of the ink pressurizing chamber is insufficient. However, it is possible to find conditions that can be put to practical use by examining conditions such as the injection pressure and adjusting the number of nozzle passes depending on the processing site.

As is apparent from the above description, in the art, an abrasive grain jetting technique that has not been considered in detail as an unsuitable manufacturing technique and thus has not been put into practical use has become a problem for a recording head. It has been found to be effective as a manufacturing technique for processing ink channel grooves on a printed circuit board. Furthermore,
The surface to be processed by the abrasive jet processing technology is excellent in ink wettability as it is, and does not require a process for improving the wettability of the processed surface. For reference, the ink contact angle and the surface roughness of the processed surface are shown as follows.
Degrees, the surface roughness is about 1 μm, the ink contact angle of the plasma etched surface is 25 to 30 degrees, and the surface roughness is 0.1 to 0.2 μm or less. For plasma-etched surfaces, reduce the ink contact angle by 600
Oxidation treatment at about ° C and subsequent alkali treatment are required. By performing the alkali treatment, an ink contact angle of about 15 degrees can be obtained.

Although the results of the above study are based on a silicon wafer, it is also effective for a glass substrate. In the invention of claim 2, the flow path substrate is made of silicon, and the diaphragm is made of borosilicate glass. As is clear from the description of the first aspect of the present invention, it is clear from the study results shown in FIGS. 1 and 2 that the abrasive grain jetting is extremely effective when a silicon wafer is used as the flow path substrate. Would. Borosilicate glass has a coefficient of thermal expansion extremely close to that of silicon and can be bonded to each other by electrostatic bonding technology, so that no member is required for bonding, high rigidity and low distortion of bonding. Very few recording heads can be manufactured.

According to a third aspect of the present invention, there is provided the method of manufacturing a recording head according to the first or second aspect, wherein the dry film is attached to the flow path substrate and pressurized to adhere the dry film to the flow path substrate. Dry film affixing step to remove, the dry film of the portion corresponding to the groove corresponding to the ink flow path of the flow path substrate is removed, the dry film patterning step of exposing the flow path substrate surface of the groove processing portion, Using the patterned dry film as a mask, an abrasive spray processing step of forming grooves corresponding to the ink flow paths in the flow path substrate by abrasive spray processing, removing the dry film on the flow path substrate, and removing the flow path substrate. And a dry film removing / washing step for washing.

As described in the description of the first aspect of the present invention, a mask pattern corresponding to an ink flow path is formed by photolithography using a dry film as a mask material, and an ink flow path is formed by abrasive grain ejection processing. Then, the depth of the groove required for the recording head can be secured, and sufficient ink wettability can be secured. Abrasive blasting is less expensive than dry plasma etching technology, and requires less equipment because the processing time is shorter. As a result, capital investment costs per recording head Is significantly cheaper. FIG.
As is clear from the comparison between FIG. 3 and FIG. 3, the number of manufacturing steps is significantly reduced, and the number of manufacturing steps is also significantly reduced by eliminating the need for the wettability improving treatment.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a recording head and a method of manufacturing the same according to the present invention will be described with reference to examples. It is to be noted that the same reference numerals are used for portions having the same functions as those of the related art. The structure of the embodiment of the recording head according to the present invention is as follows.
This is the same as the recording head of the related art shown in FIGS. 5 and 6 (hereinafter referred to as a conventional example), and will be described with reference to FIGS. The difference between the embodiment and the conventional example is that the ink flow channel 11 formed in the flow channel substrate 1, the ink reservoir 7, and the ink flow channel serving as the ink injection port 12 are formed by abrasive grain ejection processing. is there. An embodiment of the manufacturing method will be described mainly on the formation of the ink flow channel.

FIG. 3 is a manufacturing process diagram showing a manufacturing process in which a silicon wafer is used as a material of the flow channel substrate 1 and an ink flow channel is formed by photolithography and abrasive spraying technology. First, a 0.76mm-thick mirror-polished silicon wafer is used as a material, and a 50μm-thick positive type dry film is adhered to one or both sides of this silicon wafer, and pressed firmly with a roller, etc. (Step 1
c). On this dry film, a plurality of inks including an ink nozzle 2, a nozzle flow path 3, an ink pressurizing chamber 4, an ink supply path 5, and a throttle flow path (a filter flow path in FIG. 5) 6 serving as a flow path resistance adjusting unit. The photomask having the pattern of the ink flow path groove to become the flow path 11 and the common ink reservoir 7 and the ink injection port 12 connected to the plurality of ink flow paths 11 is overlapped and exposed to a dry film under predetermined conditions. Then, the exposed portion of the dry film is removed, and the dry film is patterned in accordance with the shape of the ink flow channel to expose the silicon surface (photolithography) (Step 2).
c). Next, using the patterned dry film as a mask, an ink flow channel is formed by an abrasive spraying technique (step 3c). Finally, the flow path substrate 1 is completed by removing the dry film and cleaning the silicon wafer on which the ink flow path grooves are formed (step 4c).

As the abrasive grain spraying process, the material of the abrasive grain: alumina The grain size of the abrasive grain: 800 mesh The spray pressure: 0.25 MPa The distance between the spray nozzle and the wafer surface: 100 mm The moving speed of the spray nozzle: 50 mm / sec The moving pitch: When the condition of 10mm nozzle pass: 8 times is adopted, the ink nozzle 2 of 50μm width, 800μm length and 43μm depth, and 2mm width, 2.15mm length and 65μm depth are formed on a silicon wafer by one processing. And an ink passage groove including the ink pressurizing chamber 4.

Incidentally, 24 ink nozzles 2 are formed at a pitch of 0.25 mm on one side, and 200 d when arranged on both sides.
The pitch is 0.125 mm, which corresponds to the resolution of pi. After the abrasive grain blasting, the dry film was removed by a predetermined process, followed by washing and drying to obtain the flow path substrate 1. A diaphragm 8 made of a borosilicate glass plate having a thickness of 0.2 mm is electrostatically bonded to the flow path substrate 1 thus obtained, and laminated and integrated.
The diaphragm 8 corresponding to the ink pressurizing chamber 4 is formed.
A piezoelectric element 9 as an electromechanical conversion element was adhered to the surface on the opposite side with an adhesive layer 10 to complete a recording head.

Note that an epoxy-based adhesive was used for the adhesive layer 10. The bubble removal characteristics and ink ejection characteristics when the recording head thus prepared is filled with the aqueous ink are as follows. The suction negative pressure of the pump capable of completely removing air bubbles in the recording head is 43 k in the embodiment.
Pa, a value lower than 59 kPa in the conventional example.

The ink ejection speed when a drive voltage of 85 V is applied to the piezoelectric element 9 is 8.5 m / sec or more, which is equivalent to that of the conventional example, and the frequency characteristics can be obtained up to 10 kHz. In this respect, the embodiment and the conventional example are equivalent. In the case of the alkaline treatment in the conventional example, the recording head is filled with an alkaline solution of pH 12
Hold for hours. On the other hand, the examples were not subjected to the alkali treatment.

In the above embodiment, the material of the flow path substrate 1 is a silicon wafer, the material of the abrasive grains for processing is alumina, and the grain size of the abrasive grains is 800 mesh.
In the case of a recording head that does not require much resolution, it is sufficiently possible to use a glass plate for the flow path substrate 1. Further, the material of the abrasive grains can be changed to zirconia or the like, and the grain size of the abrasive grains can be changed. However, when the grain size of the abrasive grains is changed to a smaller one, although finer processing is possible, in order to obtain an ink flow path groove of a predetermined size, it is necessary to increase the number of nozzle passes and increase the ink pressure. It is necessary to increase the number of nozzle passes of the deeply carved portion such as the chamber 4 as compared with the shallow carved portion of the ink nozzle 2 or the like.

It is also possible to replace a positive dry film with a negative dry film. As is apparent from the above description, by replacing the processing of the ink flow path grooves of the flow path substrate 1 with the abrasive jet processing, it is possible to reduce the equipment cost while securing the same or higher ink ejection characteristics as the conventional example. As a result, the manufacturing process can be simplified, and the number of manufacturing steps can be reduced.

[0028]

According to the first aspect of the present invention, the ink passage grooves of the passage substrate of the recording head are grooves formed by abrasive grain ejection processing. According to the result of the study by the inventor of the present invention, as described in the section of "Means for Solving the Problems", by the abrasive grain injection processing that would be considered unsuitable from the conventional common sense, It is possible to form an ink flow channel in the flow channel substrate. In addition, according to the abrasive jet processing, the processing dimensions required as a recording head can be obtained in a short time, and the reproducibility is excellent. It does not require a process for improving the wettability of the processed surface. Therefore, according to the present invention, it is possible to process the ink flow channel with less expensive manufacturing equipment while utilizing the advantages of the conventional technology, and to reduce the processing time and the number of manufacturing steps required for manufacturing the recording head. Can be done.

According to the second aspect of the present invention, the flow path substrate is made of silicon, and the diaphragm is made of borosilicate glass. As is clear from the description in the section of "Means for Solving the Problems", this configuration is a configuration that can most effectively utilize the advantages of the abrasive grain ejection processing technology, and has excellent characteristics as a recording head. I have. According to a third aspect of the present invention, there is provided a manufacturing method for forming an ink flow path groove in a flow path substrate of a recording head according to the first or second aspect, wherein a dry film is used as a mask material, and the ink flow path is formed by photolithography. When a mask pattern corresponding to the above is formed and an ink flow path is formed by abrasive grain ejection processing, it is possible to secure the depth of the groove necessary for the recording head and to secure sufficient ink wettability. Abrasive grain blasting is less expensive than dry plasma etching technology, and requires less equipment because the processing time is shorter.
As a result, the capital investment cost per recording head is greatly reduced. Further, as is apparent from the comparison between FIGS. 4 and 3, the number of manufacturing steps is significantly reduced, and the number of manufacturing steps is significantly reduced by eliminating the need for the wettability improving treatment.

[Brief description of the drawings]

FIG. 1 is a diagram showing a relationship between a mask width and a processing depth in abrasive grain injection processing using 800 mesh alumina.

FIG. 2 is a diagram showing the relationship between abrasive grain size and machining depth in abrasive grain injection machining with alumina.

FIG. 3 is a manufacturing process diagram showing a method for manufacturing a recording head according to the present invention.

FIG. 4 is a manufacturing process diagram showing a method for manufacturing a recording head according to a conventional technique.

FIG. 5 is a pattern diagram showing an example of an ink channel groove of the channel substrate.

FIG. 6 is a sectional view showing the structure of a recording head.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 flow path substrate 2 ink nozzle 3 nozzle flow path 4 ink pressurization chamber 5 ink supply path 6 filter flow path 7 ink reservoir 11 ink flow path 12 ink inlet 8 vibration plate 9 piezoelectric element 10 adhesive layer

Continuation of the front page (72) Inventor Masaki Shinoda 1-1-1 Tanabe-Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture F-term in Fuji Electric Co., Ltd. (reference) 2C057 AF93 AG44 AP22 AP43 AQ02 BA03 BA14

Claims (3)

[Claims] 1. A flow path substrate in which a groove corresponding to the entire ink path from an ink supply section to an ink nozzle or at least a part of an ink path including an ink pressurizing chamber and an ink nozzle is formed. A vibrating plate joined to the groove side of the passage substrate to cover the groove of the passage substrate to form an ink passage, and a piezoelectric element to which a piezoelectric element for pressurizing the ink pressurizing chamber is joined on the opposite surface; , Wherein the groove for the ink passage is a groove formed by abrasive spraying. 2. The apparatus according to claim 1, wherein said flow path substrate is made of silicon, and said diaphragm is made of borosilicate glass.
3. The ink jet recording head according to item 1. 3. The method for manufacturing an ink jet recording head according to claim 1, wherein a dry film is attached to the flow path substrate and pressurized to adhere the dry film to the flow path substrate. A dry film patterning step of removing a portion of the dry film corresponding to the groove corresponding to the ink flow path of the flow path substrate and exposing a flow path substrate surface at a portion where the groove is processed; An abrasive spraying process for forming grooves corresponding to ink channels in the flow path substrate by abrasive spraying using the film as a mask, and a dry film for removing the dry film on the flow path substrate and cleaning the flow path substrate A method for manufacturing an ink jet recording head, comprising: a removing / cleaning step.