JP3749320B2 - Manufacturing method of liquid chamber parts - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing an inkjet head used in an apparatus such as a printer that ejects ink droplets to form an ink image on a medium such as recording paper, and more particularly to a liquid chamber component that is a component constituting the inkjet head.
[0002]
[Prior art]
A conventional piezoelectric ink-jet head doubles as a piezoelectric element that generates a driving force by an electrostrictive effect in order to eject ink, a diaphragm that transmits the driving force generated by the piezoelectric element to a liquid chamber, an ink flow path, and a pressure chamber. It comprises a liquid chamber part provided with a liquid chamber and a nozzle plate provided with ink discharge holes (hereinafter referred to as nozzles) for discharging ink pressurized in the liquid chamber.
[0003]
FIG. 5 shows an example of a conventional piezoelectric ink jet head. The liquid chamber component 10 has a large number of deep groove-like liquid chambers 5 serving as ink flow paths and ink pressurizing chambers. Each liquid chamber 5 corresponds to a nozzle 6 formed in the nozzle plate 11, and one nozzle 6 is arranged in one liquid chamber 5. Therefore, in order to increase the resolution of the ink jet head, it is necessary to narrow the interval between the liquid chambers 5 formed in the liquid chamber component 10. The nozzle plate 11 and the liquid chamber part 10 are usually joined with an adhesive.
[0004]
Diaphragm 7 is generally formed with a protruding groove about 20 μm called island 9 on a thin plate of about 3 to 5 μm. This island 9 is for reliably transmitting the distortion to the liquid chamber 5 when the piezoelectric element 8 expands and contracts due to the electrostrictive effect. Therefore, the islands 9 are arranged so as to overlap the corresponding liquid chambers 5 and piezoelectric elements 8. The liquid chamber part 10 and the diaphragm 7 are joined with an adhesive. At that time, the adhesive should not protrude from the liquid chamber as much as possible.
[0005]
The piezoelectric elements 8 correspond to the respective liquid chambers 5 of the liquid chamber components 10 and are separated so as not to affect the other liquid chambers 5. These separated piezoelectric elements 8 are fixed on a base 12. In general, for manufacturing reasons, the piezoelectric element 8 that is not separated at first is joined to the base 12 with an adhesive, and then only the piezoelectric element 8 is separated by cutting. In a state where the piezoelectric elements 8 and the base 12 are bonded, the piezoelectric elements 8 and the islands 9 formed on the diaphragm 7 corresponding thereto are bonded with an adhesive.
[0006]
As a conventional method for forming a liquid chamber part of a piezoelectric ink jet head, a method of forming an organic material such as Epox by an injection molding method has been common. In addition, there is a molding method using a processing method called a powder injection molding method in which an oxide such as ZrO ₂ is molded by injection molding instead of an organic material. These molding methods always require a mold. However, since a very large pressure is applied when injecting a material into the mold, it is difficult to make the mold into a fine shape, and these methods are not suitable for a fine shape.
[0007]
Etching is an example of a processing method suitable for forming a fine shape. By using etching, it is possible to easily pattern a thick metal plate of about several hundred μm into a groove shape. However, in this method as well, in terms of increasing the density, the groove width that is about the same as the film thickness is the limit, and is not so effective. In the case of etching, since the groove penetrates, a plate-like material must be pasted on one of the surfaces of the metal plate to use it as a liquid chamber part, and the process becomes complicated.
[0008]
In addition, as a method for forming a nozzle plate of a conventional piezoelectric inkjet head, an electroforming method or a press working method has been used.
[0009]
The liquid chamber part and the nozzle plate made separately are joined by an adhesive or the like. The point required in the joining process is to make the adhesive layer as thin as possible so that it does not protrude into the liquid chamber or nozzle, and so that the ink in each liquid chamber does not conduct to other liquid chambers. It is to be firmly bonded. These requirements become more difficult as the inkjet head advances in the direction of higher density.
[0010]
[Problems to be solved by the invention]
In recent years, higher density of 180 dots per inch (hereinafter referred to as 180 dpi) or more is being demanded. Naturally, the distance between the liquid chambers and the distance between the nozzles are required to be 180 dpi. The interval corresponding to 180 dpi means that the liquid chamber and the nozzle are formed at an interval of 141 μm. In the liquid chamber, it means that a wall separating the liquid chamber and the liquid chamber is formed between 141 μm. When the ratio between the liquid chamber width and the wall thickness is 1: 1, the liquid chamber width is 70.5 μm, and the wall thickness is 70.5 μm.
[0011]
In the conventional ink jet head, as described above, the liquid chamber part and the nozzle plate are formed separately, and an adhesive is applied to the cross section of the wall partitioning the liquid chamber of the liquid chamber part to join the nozzle. However, as the density of ink jet heads increases, it becomes difficult to bond with an adhesive, and it is almost impossible to stably apply an adhesive at a density exceeding 180 dpi. Even if it is painted, it becomes very weak in terms of bonding strength.
[0012]
Further, when the liquid chamber part and the nozzle plate are joined, the liquid chamber and the nozzle must be aligned. However, the higher the density is, the more difficult the alignment is. If this alignment is not successful and misalignment occurs, the ink ejection direction deviates significantly, and high-definition printing cannot be obtained.
[0013]
[Means for Solving the Problems]
In the present invention, in order to solve the above problems, an opaque film is first formed in a desired shape on a transparent substrate. Next, a photosensitive resin was coated on the substrate, and then the photosensitive resin was patterned by two photolithography processes, thereby forming a liquid chamber part including both a nozzle and a liquid chamber.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
(Example 1)
FIG. 1 is a view showing a first embodiment of a method for producing a liquid chamber part of an ink jet head according to the present invention. First, as shown in FIG. 1A, a planar shape of a desired liquid chamber and nozzle is patterned on an opaque film 2 on a transparent substrate 1. In FIG. 1A, l1 is the length of the nozzle, b1 is the width of the nozzle, and b2 is the width of the liquid chamber. In this embodiment, the dimensions are l1 = 100 μm, b1 = 40 μm, and b2 = 70 μm. In this embodiment, a 0.4 mm thick glass substrate was used as the transparent substrate 1 and a Cr film was used as the opaque film 2.
[0015]
The Cr film patterning process performed in this example will be described below. First, the Cr film was formed by sputtering, and the film was formed for 4 minutes at 450 W RF power under the condition of Ar gas pressure of 0.01 torr. As a result, the film thickness of the Cr film was 0.1 μm.
Thereafter, the Cr film was patterned into a desired shape by a wet etching method. The process of the wet etching method performed in this example is shown below. First, a photosensitive resist was coated on the Cr film by spin coating. As the photosensitive resist, AZ-4620 manufactured by DuPont was used, and spin coating was performed at 4000 rpm for 30 seconds to coat with a thickness of 6 μm.
[0016]
Next, the photosensitive resist AZ-4620 is patterned using an exposure mask having a desired liquid chamber and nozzle shape. Since AZ-4620 is a positive resist, a mask in which a desired liquid chamber and a nozzle shape are drawn with a Cr film was used as an exposure mask used here. The exposure of AZ-4620 was performed under the condition of 100 mJ / cm ² , and the development was performed by immersing in a dedicated developer at 25 ° C. for 1 minute.
Thereafter, the Cr film was patterned by a wet etching method in a state where AZ-4620 was patterned on the Cr film. As an etching solution, an aqueous solution in which 16 cc of perchloric acid and 32 g of ceric ammonium nitrate were mixed in 800 cc of water was used.
[0017]
Finally, the substrate is immersed in acetone, AZ-4620 is peeled off, and patterning of the Cr film is completed.
[0018]
In the next step of FIG. 1B, after the first photosensitive resin 31 is coated on the transparent substrate 1 on which the opaque film 2 is patterned, the first photosensitive resin 31 is used using the exposure mask 4. Are exposed. Unlike the exposure mask used for the patterning of the opaque film 2, the exposure mask 4 used in this process has only the planar shape of the liquid chamber drawn with a Cr film.
[0019]
In this embodiment, a negative photosensitive resist called THB-30 manufactured by Nippon Synthetic Rubber Co. was used for the first photosensitive resin 31. In addition, a spin coat method was used for coating the first photosensitive resin 31, and in this example, the substrate was rotated at 1000 rpm for 10 seconds. Under the above-described spin coating conditions, the first photosensitive resin 31 THB-30 was coated with a film thickness of 60 μm.
[0020]
In exposure of the first photosensitive resin 31, the exposure mask 4 is aligned and exposed at a predetermined position of the pattern of the opaque film 2 formed on the transparent substrate 1. Since THB-30 used in this example is colorless and transparent, alignment can be easily performed. In general, alignment of a mask in a photolithography process is widely used in the LSI field, and alignment at a submicron level is possible. In this example, exposure was performed under the condition of 300 mJ / cm ² .
[0021]
The process of FIG. 1C is a process of performing exposure from the transparent substrate 1 side after coating the second photosensitive resin 32 on the first photosensitive resin 31. In this example, THB-30 was used as the second photosensitive resin 32 as in the case of the first photosensitive resin 31. Similarly, the spin coating method was used as the coating method. However, in this process, spin coating was performed at a rotation speed of 1600 rpm for 10 seconds, and the film thickness of the second photosensitive resin 32 was set to 40 μm.
[0022]
The exposure amount in this process must expose the second photosensitive resin 32 through the transparent substrate 1 and the first photosensitive resin 31, and therefore it is necessary to expose more than the exposure amount in FIG. There is. In this example, exposure was performed under conditions of 600 mJ / cm ² .
[0023]
Finally, the first photosensitive resin 31 and the second photosensitive resin 32 are simultaneously developed to form a nozzle-integrated liquid chamber component as shown in FIG. In this example, the developer dedicated to THB-30 was used as the developer, and development was performed by dipping for 5 minutes at a liquid temperature of 35 ° C.
[0024]
(Example 2)
FIG. 2 is a view showing a second embodiment of the method of manufacturing the liquid chamber part of the ink jet head according to the present invention. First, as shown in FIG. 2A, a desired liquid chamber planar shape is patterned on the transparent substrate 1 by the opaque film 2. In FIG. 2A, b2 is the width of the liquid chamber, and in this embodiment, b2 = 70 μm. Also in the second embodiment, a glass substrate having a thickness of 0.4 mm was used as the transparent substrate 1 in the same manner as in the first embodiment, and a 0.1 μm Cr film was patterned as the opaque film 2. The Cr film was formed and patterned under exactly the same conditions as in the first example.
[0025]
In the second embodiment, as shown in FIG. 2B, after the first photosensitive resin 31 is coated on the transparent substrate 1 on which the opaque film 2 is patterned, exposure is performed from the transparent substrate 1 side. . In this process, THB-30 was used as the photosensitive resin 31, and was spin-coated at a rotation speed of 1000 rpm for 10 seconds, and was coated at a thickness of 60 μm. The exposure was performed with an exposure amount of 400 mJ / cm ² .
[0026]
In the next step of FIG. 2C, the second photosensitive resin 32 is coated on the first photosensitive resin 31, and exposure is performed using the exposure mask 4. The exposure mask 4 used in the second embodiment is such that a desired liquid chamber and the planar shape of the nozzle are drawn with a Cr film. Also in this example, THB-30 was used for the photosensitive resin 32. As for coating, the spin coating method was used as before. The coating condition was a rotation of 1600 rpm for 10 seconds. Under this condition, the photosensitive resin 32 was coated to a thickness of 40 μm. In this process, the photosensitive resin 32 was exposed at 300 mJ / cm ² .
[0027]
Finally, the first photosensitive resin 31 and the second photosensitive resin 32 are simultaneously developed to form a nozzle-integrated liquid chamber part as shown in FIG. The development in the second example was performed under the same conditions as in the step of FIG. 1D of the first example.
[0028]
(Example 3)
FIG. 3 is a view showing a third embodiment of the method of manufacturing the liquid chamber part of the ink jet head according to the present invention. First, as shown in FIG. 3A, a desired liquid chamber and a planar shape are patterned on the transparent substrate 1 by the opaque film 2. In the third embodiment, the configurations of the transparent substrate 1 and the opaque film 2 are exactly the same as those in the first embodiment.
[0029]
FIG. 3B is a process of exposing using the exposure mask 4 after coating the photosensitive resin 31 on the transparent substrate 1 as in FIG. However, the exposure mask 4 used in the third embodiment has a mask shape not covered with a Cr film so that only the vicinity of the nozzle is exposed. The photosensitive resin 31 in this process also uses THB-30, and coating and exposure were performed under the same conditions as those in the process of FIG. 1B in the first example. The major feature of the third embodiment is that the alignment of the exposure mask 4 is easier than that of the first embodiment.
[0030]
FIG. 3C shows a process in which the photosensitive resin 31 is coated on the photosensitive resin 31 and exposure is performed from the transparent substrate 1 side, as in FIG. Prior to this process, the photosensitive resin 31 is not exposed except in the vicinity of the nozzle, so that the portion other than the vicinity of the nozzle is exposed in the same shape simultaneously with the exposure of the photosensitive resin 32. THB-30 was used for the photosensitive resin 32 also in this process. The coating and exposure conditions are the same as the process conditions in FIG. 1C of the first embodiment.
[0031]
Finally, as shown in FIG. 3D, the photosensitive resin 31 and the photosensitive resin 32 are simultaneously developed to form a nozzle-integrated liquid chamber part. Development conditions were the same as those in FIG. 1D of the first embodiment.
[0032]
FIG. 4 is a view showing a configuration of an ink jet head using a nozzle-integrated liquid chamber part manufactured through the process in the third embodiment. The liquid chamber 5 has a trapezoidal cross-sectional shape with a depth of 100 μm and a width of 70 μm. This shape is because the first photosensitive resin 31 and the second photosensitive resin 32, which are negative resists, were exposed from the substrate side 1, and in the case of an exposure method using a normal exposure mask, the shape is reversely tapered. The taper angle of the wall surface of the main liquid chamber is about 7 degrees. In conventional liquid chamber parts by injection molding, the liquid chamber wall surface has a taper angle of 10 degrees or more for mold release. In the present invention, the taper angle can be 10 degrees or less, which is advantageous in forming a high-density liquid chamber.
[0033]
According to the third embodiment, the cross-sectional shape of the nozzle 6 is also formed in a trapezoidal shape like the liquid chamber 5. The nozzle formed according to the third embodiment is 40 μm deep, 40 μm wide and 100 μm long.
[0034]
A diaphragm 7 is bonded to the liquid chamber part 10 including the liquid chamber 5 and the nozzle 6 described above by adhesion. A projection called an island 9 is formed on the diaphragm 7 in order to efficiently transmit the driving force of the piezoelectric element 8 to the liquid chamber 5. This island 9 is arranged in alignment with the liquid chamber 5. The diaphragm 7 is generally formed by electroforming.
[0035]
Piezoelectric elements 8 that generate a driving force are joined to the islands 9 on the diaphragm 7 to complete the main part of the inkjet head.
[0036]
【The invention's effect】
According to the present invention, since the liquid chamber part is provided with the liquid chamber and the nozzle, the conventional process of bonding the liquid chamber part and the nozzle plate can be eliminated, and the ink jet head manufacturing process can be simplified. In addition, since the alignment operation between the nozzle and the liquid chamber at the time of bonding is eliminated, it is possible to prevent a defect due to the displacement of the nozzle that occurs at the time of bonding. In addition, poor ink conduction between the liquid chambers due to insufficient adhesion can be prevented.
[0037]
In addition, according to the present invention, since the liquid chamber and the nozzle are aligned by using a photolithography technique generally used in the LSI field, the alignment accuracy is very high. If a photolithographic technique is used, the sub-micron alignment is possible. Therefore, it can be manufactured with a sufficient margin for higher density of 180 dpi or more.
[Brief description of the drawings]
FIG. 1 is a view showing a manufacturing method according to a first embodiment of a liquid chamber part of an ink jet head of the present invention.
FIG. 2 is a view showing a manufacturing method according to a second embodiment of the liquid chamber part of the ink jet head of the present invention.
FIG. 3 is a view showing a manufacturing method according to a third embodiment of the liquid chamber part of the ink jet head of the present invention.
FIG. 4 is a diagram showing a configuration of an ink jet head using a liquid chamber part manufactured according to the present invention.
FIG. 5 is a diagram illustrating a component configuration of a conventional inkjet head.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Transparent substrate 2 Opaque film | membrane 4 Exposure mask 5 Liquid chamber 6 Nozzle 7 Diaphragm 8 Piezoelectric element 9 Island 10 Liquid chamber component 11 Nozzle plate 12 Base 31 1st photosensitive resin 32 2nd photosensitive resin

Claims (2)

A liquid chamber part having a liquid chamber for storing ink and serving as a pressure chamber, and a nozzle that is a discharge hole for discharging the ink pressurized in the liquid chamber, and a liquid chamber part joined to the liquid chamber part. A method of manufacturing a liquid chamber part in a piezoelectric inkjet head comprising a diaphragm that acts as a diaphragm for pressurizing ink and a piezoelectric element that vibrates the diaphragm by obtaining a driving force by an electrostrictive effect,
Patterning an opaque film in a desired shape on a transparent substrate;
Coating the first photosensitive resin material on the transparent substrate patterned with the opaque film, and exposing to a desired shape using an exposure mask;
Coating the second photosensitive resin material on the first photosensitive resin material, and performing exposure through the transparent substrate;
A method for producing a liquid chamber part, comprising the step of simultaneously developing the first photosensitive resin material and the second photosensitive resin material. 2. The method of manufacturing a liquid chamber part according to claim 1 , wherein in the step of exposing to a desired shape using the exposure mask, the pattern of the opaque film and the exposure mask are aligned and exposed. .

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