JP2009172871A - Manufacturing method of liquid discharge head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a liquid discharge head by which the gradient or variation in the thickness of a coating resin layer is reduced to stably make satisfactory printing. <P>SOLUTION: The manufacturing method includes steps of: forming on a substrate a first layer containing an epoxy resin expressed by formula (I), an ultraviolet absorption agent, and a photopolymerization initiator; laminate-forming on the first layer a second layer containing an epoxy resin expressed by formula (I) and photopolymerization initiator; and forming a passage and a discharge port in a coating resin layer formed from the first and second layers. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a liquid discharge head that discharges liquid, and more specifically to a method of manufacturing an ink jet recording head that performs recording by discharging ink onto a recording medium.

  An ink jet recording head applied to an ink jet recording method (liquid jet recording method) generally has a fine recording liquid discharge port (hereinafter also referred to as an orifice), a liquid flow path, and liquid discharge energy provided in a part of the liquid flow path. A plurality of generators are provided. With the recent progress of recording technology, higher-definition and higher-speed recording is required for the inkjet recording technology. One method for satisfying high-definition recording is minimization of ink droplets ejected by the ink jet recording head, that is, miniaturization of the ink jet recording head.

Conventionally, as a method for producing such an ink jet recording head, the following steps described in Patent Document 1 are known. First, an ink flow path pattern is formed of a soluble resin on a substrate on which an ink discharge pressure generating element is formed. Next, a coating resin containing at least an epoxy resin and a curing agent is dissolved in a solvent, and this is solvent-coated on the soluble resin layer, thereby forming an ink flow path wall on the soluble resin layer. A coating resin layer is formed. Next, an ink discharge port is formed in the coating resin layer above the ink discharge pressure generating element. Then, the soluble resin layer is eluted to form an ink flow path. Moreover, the following processes described in Patent Document 2 are known. First, a coating resin containing an ultraviolet absorber is coated as a first layer on a substrate on which an ink discharge pressure generating element is formed. Next, a coating resin not containing an ultraviolet absorber is coated thereon as a second layer. Then, an ink discharge port is formed in the coating resin layer above the ink discharge pressure generating element.
JP-A-6-286149 US Pat. No. 6,902,259

  By the way, in the method described in Patent Document 2, after the step of forming the second layer, surface undulation may occur due to the difference in film thickness of the covering resin layer between the central portion and the outer peripheral portion of the substrate. This is a method of forming a first layer containing an epoxy resin represented by the following formula (I) and a photopolymerization initiator, and then converting the epoxy resin represented by the following formula (I) and the photopolymerization initiator into a polar solvent. This is seen when the second layer is formed by spin coating after being dissolved in γ-butyrolactone.

  Normally, when spin coating is performed, as shown in FIG. 9, the silicon wafer 1 as a substrate is set on the substrate holder 9 and is fixed by a vacuum chuck or the like. And after dripping the coating liquid 11 in the center part of the silicon wafer 1 from the coating nozzle 10 of a spinner, the silicon wafer 1 is rotated, the coating liquid 11 is spread over the whole silicon wafer 1, and film thickness distribution is made uniform. The number of rotations is set to a number that allows a necessary film thickness to be obtained.

  However, after the first layer is coated, the coating liquid 11 containing the epoxy resin represented by the formula (I) and the photopolymerization initiator is dropped onto the first layer from the spinner coating nozzle 10. In the central portion of the wafer 1, the first layer is dissolved by the solvent. On the other hand, in the outer peripheral portion of the silicon wafer 1, since the solvent and the first layer are in slight contact with each other when the spinner rotates, it hardly dissolves. For this reason, as shown in FIG. 10, the coating resin layer composed of the first layer 3 and the second layer 4 can have a difference in thickness between the central portion and the outer peripheral portion of the silicon wafer 1. . Thereafter, a process such as cutting with a dicing blade is performed, but the film thickness of the coating resin layer varies between a chip cut from the center portion of the silicon wafer 1 and a chip cut from the outer peripheral portion. Further, as shown in FIG. 11, there is a chip in which the surface of the coating resin layer is inclined. When printing is performed with such an ink jet recording head, the ejection direction of the ejected ink droplets may vary, and the output image may be uneven.

  As described above, the above-described inkjet recording head manufacturing method has a technical problem that waviness occurs in the central portion of the substrate.

  An object of the present invention is to solve the problems described above, and to provide a method of manufacturing a liquid discharge head that can suppress the inclination and variation of the thickness of the coating resin layer and stably obtain good printing.

  The present invention relates to a method for manufacturing a liquid discharge head having a coating resin layer in which a liquid flow path and a discharge port for discharging a liquid are formed on a substrate, and is represented by the formula (I) on the substrate. A step of forming a first layer containing an epoxy resin, an ultraviolet absorber and a photopolymerization initiator, and an epoxy resin represented by formula (I) and a photopolymerization initiator on the first layer, And a step of forming the flow path and the discharge port in a coating resin layer composed of the first layer and the second layer. This is a method for manufacturing a liquid discharge head.

  According to the present invention, it is possible to manufacture a liquid discharge head that can suppress inclination and variation in the thickness of the coating resin layer and can stably obtain good printing.

  The present invention is a method of manufacturing a liquid discharge head having a coating resin layer in which a liquid channel and a discharge port for discharging a liquid are formed on a substrate. Hereinafter, embodiments of each process for manufacturing an ink jet recording head which is a liquid discharge head will be described.

First, a first layer containing an epoxy resin represented by formula (I), an ultraviolet absorber, and a photopolymerization initiator is formed on a substrate. For example, a silicon wafer can be used as the substrate. On the substrate, an ink discharge pressure generating element such as an electrothermal conversion element or a piezoelectric element is formed, and a control signal input electrode for operating the element is further connected. On the substrate, an inorganic insulating layer such as SiN or SiO ₂ or an anti-cavitation layer such as Ta may be provided.

  As a method for forming the first layer, a method in which a coating solution in which an epoxy resin represented by formula (I), an ultraviolet absorber, and a photopolymerization initiator are dissolved in a solvent is wet-coated on a substrate is preferable. As the solvent, it is preferable that the epoxy resin represented by the formula (I), the ultraviolet absorber, and the photopolymerization initiator are dissolved and have characteristics such as appropriate volatility suitable for the thin film coating method. From these viewpoints, γ-butyrolactone or cyclopentanone is suitable as the solvent. The thickness of the first layer to be formed is preferably 5 to 30 μm. The first layer can also be formed by forming a dry film of the epoxy resin represented by the formula (I), the ultraviolet absorber, and the photopolymerization initiator and laminating the dry film on the substrate.

  As the epoxy resin represented by the formula (I), a polyfunctional novolac type epoxy resin can be used. As the photopolymerization initiator, for example, a cationic polymerization initiator such as an aromatic iodonium salt or an aromatic sulfonium salt can be used. Any ultraviolet absorber may be used as long as it has absorption in the photosensitive region for curing the epoxy resin represented by formula (I) with a photopolymerization initiator. For example, a benzophenone-based or salicylic acid-based ultraviolet absorber can be used.

  The compounding quantity of each component is not specifically limited, What is necessary is just to determine suitably as desired. As will be described later, since the first layer is exposed through the second layer, the sensitivity is determined in consideration of the sensitivity and thickness of the first layer, the sensitivity and thickness of the second layer, the exposure amount, and the like. do it. Usually, when the epoxy resin represented by the formula (I) is 100 parts by mass, the photopolymerization initiator is preferably 0.2 to 10 parts by mass. Moreover, it is preferable to set it as the quantity which does not exceed 10 mass parts with respect to the sum total of the epoxy resin and photoinitiator which are represented by Formula (I), and shall be 0.1-10 mass parts Is more preferable. When the amount of the ultraviolet absorber exceeds 10 parts by mass, the sensitivity of the first layer is lowered, and it may be difficult to form a flow path and a discharge port. About a coating liquid, the resin composition 1 which consists of the epoxy resin represented by a formula (I), a ultraviolet absorber, and a photoinitiator and a total of 100 mass parts of a solvent, resin composition 1 is 20-80 mass parts. The solvent is preferably 20 to 80 parts by mass.

  Furthermore, an additive etc. can be suitably added to a 1st layer as needed. For example, a silane coupling agent may be added in order to obtain further adhesion with the substrate.

  Next, a second layer containing an epoxy resin represented by formula (I) and a photopolymerization initiator is formed on the first layer by lamination.

  The second layer is formed by a laminating method. Specifically, first, a coating solution in which an epoxy resin represented by formula (I) and a photopolymerization initiator are dissolved in a solvent is applied to a base film such as a PET film, and dried to form a dry film. Press the dry film side onto the first layer and pressurize while warming. Then, a 2nd layer can be transcribe | transferred on a 1st layer by peeling a base film. That is, since the second layer is formed in advance as a dry film and laminated on the first layer, the first layer does not come into contact with the solvent. Therefore, the undulation that occurs when the second layer is formed by spin coating is suppressed.

  The epoxy resin and photopolymerization initiator represented by the formula (I) can be the same as described above. In addition, it is preferable not to use an ultraviolet absorber. The compounding quantity of each component is not specifically limited, What is necessary is just to determine suitably as desired. As will be described later, since the second layer is exposed with light having an intensity that does not expose the first layer, the sensitivity and thickness of the first layer, the sensitivity and thickness of the second layer, the exposure amount, etc. It may be determined in consideration of. Usually, when the epoxy resin represented by the formula (I) is 100 parts by mass, the photopolymerization initiator is preferably 0.2 to 10 parts by mass. About a coating liquid, 20-80 mass parts is preferable as resin composition 2 as a resin composition 2 consisting of the epoxy resin represented by Formula (I), and a photoinitiator, and a total of 100 mass parts of a solvent, Is preferably 20 to 80 parts by mass.

  Next, a flow path and a discharge port are formed in the coating resin layer composed of the first layer and the second layer. Usually, the flow path and the discharge port are formed by patterning the first layer and the second layer by photolithography. Since the resin composition 1 that forms the first layer and the resin composition 2 that forms the second layer function as a negative resist, an exposed region remains after development and becomes an ink flow path wall.

The first layer can be exposed through the second layer. Usually, the area other than the area that becomes the flow path in the first layer is exposed. Note that the first layer containing the ultraviolet absorber has lower sensitivity than the second layer, so the exposure conditions are set in consideration of this point. For example, exposure is preferably performed at 400 to 600 mJ / cm ² .

Then, usually, the area other than the area serving as the discharge port in the second layer is exposed. However, exposure conditions are set so that the first layer is not cured by this exposure. For example, exposure is preferably performed at 50 to 200 mJ / cm ² .

  Thereafter, development with a developer is performed to obtain an ink jet recording head in which an ink flow path is formed in an unexposed area in the first layer and an ejection port is formed in an unexposed area in the second layer. It is done.

  Note that an ink supply port can be formed on the back surface of the substrate, if necessary, by a technique such as silicon anisotropic etching. In addition, heat treatment can be performed to completely cure the coating resin layer composed of the first layer and the second layer.

  Hereinafter, the present invention will be described in more detail by way of examples.

<Example 1>
First, as shown in FIG. 1, an electrothermal conversion element 2 as an ink discharge pressure generating element was arranged on a silicon wafer 1 having a crystal axis (100) as a substrate. A control signal input electrode for operating the element is connected to the electrothermal conversion element 2 (not shown). FIG. 2 is a schematic cross-sectional view when cut along the AA plane in FIG. 1, and the same schematic cross-sectional view will be described in the following steps.

  Next, as shown in FIG. 3, a coating solution in which an epoxy resin represented by formula (I), an ultraviolet absorber, and a photopolymerization initiator are dissolved in γ-butyrolactone is wet-coated on the substrate 1, 1 layer 3 was formed. As the epoxy resin represented by the formula (I), SU-8 (trade name) manufactured by Shell Chemical Company was used. As a UV absorber, 2-hydroxy-4-methoxybenzophenone was used. As the photopolymerization initiator, cationic polymerization initiator SP-170 (trade name) manufactured by ADEKA was used. The compounding ratio of the coating solution was epoxy resin / ultraviolet absorber / photopolymerization initiator / solvent = 100/1/2/70 (mass ratio) represented by the formula (I). The thickness of the formed first layer 3 was 10 μm.

  Subsequently, the coating liquid which melt | dissolved the epoxy resin represented by a formula (I) and a photoinitiator in (gamma) -butyrolactone was apply | coated to PET film, and it was set as the dry film by drying. The epoxy resin and photopolymerization initiator represented by the formula (I) are the same as those used for forming the first layer 3. The mixing ratio of the coating solution was epoxy resin / photopolymerization initiator / solvent = 100/2/70 (mass ratio) represented by the formula (I). Then, as shown in FIG. 4, the dry film was laminated on the first layer 3 to form the second layer 4. The thickness of the formed second layer 4 was 10 μm.

Next, as shown in FIG. 5, in the first layer 3 and the second layer 4, the region 5 which becomes the ink flow path wall is exposed at 500 mJ / cm ² , and the first layer 3 and the second layer 2 in the region are exposed. Layer 4 was cured. Further, as shown in FIG. 6, the region 6 that becomes the ink flow path wall only in the second layer 4 was exposed at 100 mJ / cm ² , and only the second layer 4 in the region was cured. Then, as shown in FIG. 7, by developing, a discharge port 7 having a diameter of 20 μm was formed. In addition, the area | region which was not exposed in the 1st layer 3 becomes an ink flow path, and the area | region which was not exposed in the 2nd layer 4 becomes the ejection opening 7. FIG.

  Finally, as shown in FIG. 8, the substrate 1 is etched by silicon anisotropic etching to form the ink supply port 8, and the first layer 3 and the second layer 4 are completely cured. The ink jet recording head was obtained by heating at 200 ° C. for 1 hour.

  When test printing was performed using the obtained ink jet recording head, it was confirmed that all of them had excellent print quality with no image distortion. That is, it can be seen that in the embodiment according to the present invention, a highly reliable ink jet recording head capable of stably obtaining good printing can be obtained.

<Comparative Example 1>
Except that the second layer was formed by spin-coating a coating solution prepared by dissolving the epoxy resin represented by the formula (I) and the photopolymerization initiator in γ-butyrolactone onto the first layer. In the same manner as in Example 1, an inkjet recording head was produced. When test printing was performed in the same manner as in Example 1 using the obtained ink jet recording head, printing defects were very rarely observed.

It is a typical perspective view which shows the board | substrate with which the ink discharge pressure generating element was formed. It is typical sectional drawing which shows the AA cut surface of the board | substrate of FIG. It is a typical sectional view showing the state where the 1st layer was formed on the substrate. It is a typical sectional view showing the state where the 2nd layer was formed on the 1st layer. It is typical sectional drawing which shows the state which has exposed the 1st layer and the 2nd layer. It is a typical sectional view showing the state where only the 2nd layer is exposed. It is typical sectional drawing which shows the state which formed the discharge outlet. It is a typical sectional view showing an ink jet recording head obtained by forming an ink supply port. It is a typical perspective view which shows the state which has spin-coated the coating liquid on the board | substrate. It is typical sectional drawing which shows the state from which the film thickness difference was made to the coating resin layer on a board | substrate. It is a typical sectional view showing an ink jet recording head in which the surface of a covering resin layer is inclined.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Silicon wafer 2 Electrothermal conversion element 3 1st layer 4 2nd layer 5 Area 6 Area 7 Discharge port 8 Ink supply port 9 Substrate holder 10 Coating nozzle 11 Coating liquid

Claims (3)

In a manufacturing method of a liquid discharge head having a coating resin layer in which a liquid flow path and a discharge port for discharging a liquid are formed on a substrate,
Forming a first layer containing an epoxy resin represented by the following formula (I), an ultraviolet absorber and a photopolymerization initiator on the substrate;
On the first layer, a step of forming a second layer containing an epoxy resin represented by the following formula (I) and a photopolymerization initiator by lamination;
And a step of forming the flow passage and the discharge port in a coating resin layer comprising the first layer and the second layer.

  The first layer is formed by wet-coating a coating solution prepared by dissolving the epoxy resin represented by the formula (I), the ultraviolet absorber, and the photopolymerization initiator in a solvent on the substrate. The method of manufacturing a liquid discharge head according to claim 1.   The method for manufacturing a liquid discharge head according to claim 2, wherein the solvent is γ-butyrolactone or cyclopentanone.

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