Recording element substrate and method for manufacturing the same

Abstract

To solve the problem that there is concern that air is blown into a portion of a liquid passage when filling the liquid passage with a filler, so that a filling property of the filler is impaired, which may influence precision of a discharge port.SOLUTION: A recording element substrate comprises a discharge port forming member 9 having a discharge port 11 formed therein, a liquid supply port 13, and a substrate 10 having a first surface 21 on which the discharge port forming member 9 is placed and a second surface 22 which is a rear surface of the first surface. The liquid supply port 13 has a first portion 61 connected perpendicularly to the first surface 21 and a second portion 62 connected to the first portion 61. An inner wall of the second portion 62 has an inclined surface 23 inclined with respect to an inner wall of the first portion 61 so that a width of the second portion 62 gradually becomes larger toward the second surface 22, where a hydrophilic film 24 is formed at least on the inner wall of the first portion 61.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a recording element substrate and a method for manufacturing the same.

Background Art

[0002] There is a liquid ejection device that ejects a liquid to perform recording such as an image or characters on a recording medium such as paper, such as an inkjet printer. The liquid ejection device has a liquid ejection head which is a component for ejecting the liquid. Further, the liquid ejection head has a recording element substrate. On the recording element substrate, a discharge port forming member having a discharge port for ejecting the liquid and a substrate on which the discharge port forming member is placed are formed. Further, on the substrate, an energy generating element for generating energy for ejecting the liquid from the discharge port and a liquid supply port for supplying the liquid to the discharge port are formed.

[0003] As a method for manufacturing such a liquid ejection head having a recording element substrate, there is a method described in Patent Document 1. In Patent Document 1, after forming a liquid supply port in the substrate, a filler is filled in the liquid supply port, and then, a discharge port forming member is formed. FIG. 10 is a schematic view showing a state of filling a filler in a conventional liquid supply port in Patent Document 1. As shown in FIG. 10, after attaching a tape 25 to the surface of the substrate 10 on the side where the energy generating element 2 is formed, the filler 15 is filled in the liquid supply port 13 using a dispensing needle 26.

Prior Art Documents

Patent Documents

[0004] <000002​​​​​​​​​​​​However, in Patent Document 1, the filler can trap air bubbles. Figure 11 is a schematic diagram illustrating this. As shown in Figure 10, after filling with filler 15, the filler 15 flows downwards, but because the liquid supply port 13 is formed perpendicular to the substrate 10, the filler 15 tends to flow downwards across the entire width of the liquid supply port (Figure 11(a)). As a result, the air inside the liquid supply port 13 has no escape route to the outside (upwards in the drawing), and by the time the filler 15 reaches the tape 25, the filler 15 traps air bubbles 3.

[0006] Such air bubbles, when expanded due to heat or other factors, can affect the flatness of the tape 25, and consequently, the flatness of the discharge port forming member. As a result, there are concerns that this may affect the precision of the discharge port and the print quality when droplets are discharged from the discharge port.

[0007] Therefore, the present invention aims to provide a recording element substrate and a method for manufacturing the same that can suppress the trapping of air bubbles when filling a filler into a liquid supply port formed perpendicular to the substrate. [Means for solving the problem]

[0008] To solve the above problems, the present invention provides a recording element substrate comprising: a discharge port forming member having a discharge port for discharging liquid; a liquid supply port for supplying liquid to the discharge port; a substrate having a first surface on which the discharge port forming member is placed; and a second surface which is the back surface of the first surface, wherein the liquid supply port has a first portion connected perpendicularly to the first surface and a second portion connected to the first portion, and the inner wall of the second portion is an inclined surface that is inclined with respect to the inner wall of the first portion such that the width of the second portion gradually increases toward the second surface. Preparation , before A hydrophilic film is formed on the inner wall of the first part. Furthermore, a water-repellent film is formed on the inclined surface of the inner wall of the second portion. It is characterized by being present.

[0009] Furthermore, the present invention relates to a recording element substrate comprising: a discharge port forming member having a discharge port for discharging liquid; a liquid supply port for supplying liquid to the discharge port; a substrate having a first surface on which the discharge port forming member is placed; and a second surface which is the back surface of the first surface, wherein the liquid supply port has a first portion connected perpendicularly to the first surface and a second portion connected to the first portion, and the inner wall of the second portion has an inclined surface that is inclined with respect to the inner wall of the first portion such that the width of the second portion gradually increases toward the second surface. Preparation , before A water-repellent film is formed on the inner wall of the first part. Furthermore, a hydrophilic film is formed on the inclined surface of the inner wall of the second portion. It is characterized by being present.

[0010] Furthermore, the present invention relates to a method for manufacturing a liquid discharge head, comprising: a discharge port forming member having a discharge port formed thereon for discharging liquid; a liquid supply port for supplying liquid to the discharge port; a substrate having a first surface on which the discharge port forming member is placed; and a second surface which is the back surface of the first surface, wherein the liquid supply port has a first portion connected perpendicularly to the first surface and a second portion connected to the first portion, and the inner wall of the second portion has an inclined surface that is inclined with respect to the inner wall of the first portion such that the width of the second portion gradually increases toward the second surface; forming a hydrophilic film on at least the inner wall of the first portion; attaching tape to the first surface of the substrate having the liquid supply port; dripping an aqueous filler onto the inclined surface of the inner wall of the second portion and filling the first portion with the aqueous filler; removing the tape; forming the discharge port forming member on the first surface; and removing the aqueous filler. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a recording element substrate and a method for manufacturing the same that can suppress the trapping of air bubbles when filling a filler into a liquid supply port formed perpendicular to the substrate. [Brief explanation of the drawing]

[0012] [Figure 1] Perspective view showing a liquid ejection head. [Figure 2] Schematic view and cross-sectional view of a recording element substrate. [Figure 3] Flowchart for explaining the steps of a method for manufacturing a recording element substrate according to the present invention. [Figure 4] Cross-sectional view for explaining the process of forming a liquid supply port according to the first embodiment. [Figure 5] Cross-sectional view for explaining the filling process of a filler and the forming process of a discharge port forming member according to the first embodiment. [Figure 6] Cross-sectional view showing the longitudinal direction of a recording element substrate in the first embodiment. [Figure 7] Cross-sectional view of a recording element substrate in the second embodiment. [Figure 8] Top view and cross-sectional view of a recording element substrate in Example 1. [Figure 9] Top view and cross-sectional view of a recording element substrate in Example 2. [Figure 10] Schematic view showing the state of filling a filler in a conventional example. [Figure 11] Schematic view showing the state of filling a filler in a conventional example.

BEST MODE FOR CARRYING OUT THE INVENTION

[0013] Next, preferred embodiments of the present invention will be described with reference to the drawings. In the following description, components having the same function may be given the same reference numerals in the drawings, and the description thereof may be omitted.

[0014] (First Embodiment) (Liquid Ejection Head) FIG. 1(a) is a perspective view showing the liquid ejection head 1 of the present embodiment, and FIG. 1(b) is an exploded perspective view showing each member of the liquid ejection head 1 shown in FIG. 1(a). As shown in FIG. 1(b), the liquid ejection head 1 of the present embodiment mainly includes a recording element unit 41 and a housing unit 42.

[0015] The recording element unit 41 is mainly composed of a recording element substrate 44 and 45 having a discharge port 11 (Fig. 2) for discharging a liquid, an electrical wiring substrate 48 for supplying power to the recording element substrates 44 and 45, and a support plate 47 for supporting the recording element substrates 44 and 45.

[0016] The housing unit 42 is mainly composed of a housing 43 to which a liquid container (not shown) for storing the liquid to be supplied to the discharge port 11 (Fig. 2) is connected, and a flow path forming member 46 in which a flow path for supplying the liquid from the liquid container (not shown) to the discharge port 11 is formed.

[0017] (Recording element substrate) The recording element substrate 44 will be described using Fig. 2. Fig. 2(a) is a schematic view of the recording element substrate 44. As shown in Fig. 2(a), the recording element substrate 44 includes a substrate 10 formed of silicon or the like and a discharge port forming member 9. On the substrate 10, an energy generating element 2 for generating energy for discharging the liquid from the discharge port 11 is formed.

[0018] The energy generating element 2 is electrically connected to a terminal 49 formed on the substrate 10 via an electrical wiring (not shown) made of aluminum or the like. On the surface of the terminal 49, for example, a plating layer (Au layer) made of gold is formed.

[0019] The recording element substrate 44 is electrically connected to the electrical wiring substrate 48 via the terminal 49. The energy generating element 2 receives an electrical signal from the electrical wiring substrate 48 and generates discharge energy for discharging a liquid such as ink.

[0020] The discharge port forming member 9 has a discharge port 11 for discharging liquid and a pressure chamber 12 communicating with the discharge port 11. A liquid supply port 13 is formed in the substrate 10, and the liquid is supplied from the liquid supply port 13 to the pressure chamber 12. The liquid supply port 13 is a through-hole that penetrates the substrate 10. The substrate 10 has a rectangular shape that extends in the direction of the arrangement of the energy generating elements 2, with the short side of the substrate 10 being the X direction and the long side perpendicular to the X direction being the Y direction.

[0021] Figure 2(b) is a cross-sectional view of the recording element substrate as shown in Figure 2(a) as AA'. Hereafter, the cross-sectional view of the recording element substrate 44 will refer to the cross-sectional view as shown in Figure 2(a) as AA'. In the following description, of the two surfaces of the substrate 10, the surface on which the ejection port forming member 9 is placed will be called the first surface 21, and the back surface of the first surface 21 will be called the second surface 22. An oxide film 4, for example, SiO2, and an adhesion-enhancing layer 20 are provided on the entire surface or part of the first surface 21 and the second surface 22. In addition to the oxide film 4, various inorganic films may be provided as needed. The oxide film 4 is for protecting the substrate 10 from liquids, and the adhesion-enhancing layer 20 is for improving the adhesion between the substrate 10 and the ejection port forming member 9.

[0022] The liquid supply port 13 has a first liquid flow path 51 connected perpendicularly to the first surface 21 and a second liquid flow path 52 connected to the second surface 22. In this application, perpendicular connection is not limited to a 90° connection, and variations in the first liquid flow path 51 are acceptable to account for manufacturing tolerances, etc. That is, it is sufficient that the first liquid flow path 51 is substantially connected perpendicularly to the first surface 21, and a perpendicular connection of 90 ± 5° is considered acceptable.

[0023] The first liquid channel 51 and the second liquid channel 52 are connected to each other, and liquid is supplied from the second liquid channel 52 to the first liquid channel 51, and then from the first liquid channel 51 to the discharge port 11. Here, the first liquid channel 51, which is connected perpendicularly to the first surface 21, is also referred to as the first portion 61. Furthermore, the region of the second liquid channel 52 that includes the part where the inner wall is inclined is also referred to as the second portion 62, and the part that has one end connected to the inclined surface of the inner wall of the second portion 62 and the other end connected perpendicularly to the second surface 22 is also referred to as the third portion. In other words, in Figure 2(b), the liquid supply port 13 is composed of the first portion 61, the second portion 62, and the third portion 63. Note that although Figure 2(b) shows a liquid supply port 13 having the third portion 63, the liquid supply port 13 in this embodiment does not necessarily have to have the third portion 63. In other words, the liquid supply port 13 may be formed only by the first portion 61 and the second portion 62.

[0024] The inner wall of the second portion 62 has an inclined surface 23 that is inclined with respect to the inner wall of the first portion 61 such that the width of the second portion 62 in the short direction (X direction) gradually increases toward the second surface 22. In other words, the second liquid flow path 52 is connected to the first portion 61 via the inclined surface 23.

[0025] In the first embodiment, a hydrophilic film 24 is formed on the inner wall of the first portion 61. The reason for forming the hydrophilic film 24 and the method thereof will be described in detail later.

[0026] (Manufacturing method for recording element substrates) Figure 3 is a flowchart illustrating each step of the manufacturing method for the recording element substrate in the above embodiment. Figure 4 is a cross-sectional view illustrating in detail the process of forming the recording element substrate 44 according to this embodiment, that is, the process of forming the first liquid channel 51 and the second liquid channel 52.

[0027] Figure 4(a) shows the process of laser processing from the second surface 22 side of the substrate 10 to form the second liquid channel 52. First, on the second surface 22, areas other than the area where the second liquid channel 52 is to be opened are protected with a substrate back surface protective film 17. The substrate back surface protective film 17 can be formed by a process similar to the method for forming the adhesion-enhancing layer 20 described above. Next, the opening area is formed by removing the oxide film 4 in the area not protected by the substrate back surface protective film 17. A method for removing the oxide film 4 is, for example, wet treatment with buffered hydrofluoric acid. The opening dimension of the second liquid channel 52 in the short direction (X direction) is preferably about 200 to 1500 μm. The opening dimension in the long direction is preferably about 5000 to 40000 μm, but it is preferable to set it appropriately according to the number of discharge ports 11 formed on the first surface 21.

[0028] Next, multiple unpenetrating holes (hereinafter referred to as guide holes 31) of a predetermined depth are machined with a laser from the second surface 22 side in the area to be opened. As described above, the inner wall of the second portion 62 needs to have an inclined surface 23 that is inclined with respect to the inner wall of the first portion 61 such that the width of the second portion 62 in the short direction gradually increases toward the second surface 22. Therefore, as shown in Figure 4(a), the depth of the guide holes 31 is machined according to the shape of the inclined surface 23 to be formed. In other words, the pattern and depth of the guide holes 31 can be appropriately adjusted according to the shape of the inclined surface 23 to be formed and the opening dimensions.

[0029] Figure 4(b) shows the process of forming a second liquid channel 52 by anisotropic etching. Examples of etching solutions used for anisotropic etching include strong alkaline solutions such as TMAH and KOH. The etching solution penetrates the lead holes 31, and etching progresses along the lead holes, eventually connecting the lead holes 31 to form the second liquid channel 52. If the etching time is too long, the etching will progress and the inclined surface 23 will disappear, so the etching time needs to be adjusted appropriately considering the pattern and depth of the lead holes, the desired shape of the inclined surface 23, and the opening dimensions.

[0030] Figure 4(c) shows the process of applying a liquid channel wall protective film 18 to the wall surface of the second liquid channel 52. Here, the wall surface of the second liquid channel 52 refers to the side wall portion 27 and the inclined surface 23 of the second liquid channel 52. The liquid channel wall protective film 18 acts as a mask to prevent the formation of a hydrophilic film on the wall surface of the second liquid channel 52 in the subsequent process of forming a hydrophilic film on the inner wall of the first portion 61. As a result, a hydrophilic film is formed only on the inner wall of the first portion 61. At this time, it is not necessarily required that the entire wall surface of the second liquid channel 52 be protected, but for reasons that will be explained in detail later, it is preferable that the inclined surface 23 be protected so that a hydrophilic film is formed only on the inner wall of the first portion 61.

[0031] The above-mentioned positive-type photosensitive resin can be used as the liquid channel wall protective film 18. Various coating methods such as spin coating and curtain coating can be used. The film thickness of the liquid channel wall protective film 18 is preferably about 2 to 10 μm, but any thickness that can withstand being used as a mask when forming a hydrophilic film is acceptable.

[0032] Figure 4(d) shows the process of forming the first liquid channel 51. First, on the first surface 21, a surface protective film 16 is formed in the area other than the area where the first liquid channel 51 is to be opened, using the same method as in Figure 4(a). Here, a rectangular shape is preferred for the opening of the first liquid channel 51, but a circular or elliptical shape may also be used. In the case of a rectangular shape, the corners may be rounded. The opening dimensions of the first liquid channel 51 are preferably about 30 to 200 μm, and the opening area is 900 to 40000 μm. 2 A certain degree is desirable.

[0033] Next, the first liquid channel 51 is formed by dry etching from the first surface 21 side. In addition to dry etching, the first liquid channel 51 can also be formed by laser processing. The depth of the first liquid channel 51 is already determined by the thickness of the substrate 10 and the shape of the already formed second liquid channel 52, but it is preferably about 30 to 300 μm.

[0034] Figure 4(e) shows the process of forming a hydrophilic film on the inner wall of at least the first portion 61. One method for forming the hydrophilic film is to ash the first liquid channel 51 from the first surface 21 side using oxygen plasma. This forms a hydrophilic film 24 on the inner wall of the first portion 61. A portion of the wall surface of the second liquid channel 52 is protected by the liquid channel wall protective film 18, so a hydrophilic film is not formed thereon. Note that in Figure 4(e), a hydrophilic film is formed only on the inner wall of the first portion 61 for reasons that will be explained later.

[0035] Figure 4(f) shows the process of removing the surface protective film 16, the back surface protective film 17, and the liquid channel wall protective film 18. The removal method involves using a stripping solution that can remove the positive-type photosensitive resin used.

[0036] Next, the process of filling the first portion 61 and the second liquid channel 52 formed by the method described above with the filler 15 will be explained in detail with reference to Figure 5. In the first embodiment, for example, a so-called aqueous filler, such as PVA (polyvinyl alcohol) dissolved in pure water, can be used as the filler 15. In addition, a resin dissolved in an aqueous solvent can be used, as long as it can be removed. It is sufficient that the filler 15 fills the first surface 21 side of the first portion 61 flatly, and it is not necessary for the entire first portion 61 to be filled with the filler 15. Also, it is not necessary for the second liquid channel 52 to be filled with the filler 15.

[0037] Figure 5(a) shows the process of applying tape 25 to the first surface 21 of the substrate 10 having the liquid supply port 13 to prevent the filler 15 from leaking out when filling the first portion 61 and the second liquid channel 52 with filler 15. The tape 25 is preferably made of a material that can absorb the unevenness of the first surface 21 and adhere to it so that the filler 15 does not leak out. Furthermore, if a heat treatment is performed after filling with filler 15, the tape 25 is preferably made of a material that can withstand the heating temperature. In addition, since the filler 15 will come into contact with the tape 25, the tape 25 is preferably made of a material that is resistant to the solvent of the filler 15.

[0038] Figure 5(b) shows the process of dripping aqueous filler 15 onto the inclined surface 23 of the inner wall of the second section 62 and filling the first section 61 with aqueous filler 15. As a method of filling with filler 15, for example, a filling method using a dispensing device equipped with a dispensing needle 26 that can be inserted into the second liquid channel 52 is mentioned.

[0039] Furthermore, the concept of the present invention is to drip the filler 15 onto the inclined surface 23 of the inner wall of the second portion 62 and allow it to flow down the inclined surface 23 to fill the first portion 61. Therefore, when filling, it is preferable to fill the filler 15 from directly above the inclined surface 23 so that the filler 15 flows down the inclined surface 23.

[0040] Figures 5(c) and 5(d) show how the filler 15 is filled into the first liquid channel 51. First, as shown in Figure 5(c), the filler 15, which is filled from directly above the inclined surface 23, flows down the inclined surface 23 into the first liquid channel 51. That is, due to the inclined structure, the filler 15 does not flow downward (to the first section 61) across the entire width of the liquid supply port 13 as in the conventional example, but rather flows into the first section 61 from one side of the liquid supply port 13 (inclined surface 23). As a result, within the first section 61, the filler 15 is filled from the inner wall 61a connected to the inclined surface 23 toward the inner wall 61b. Therefore, the air inside the first section 61 can escape to the outside from the inner wall 61b side in accordance with the flow of the filler 15, as shown by the airflow (arrow) 5 in Figure 5(d).

[0041] Furthermore, since a hydrophilic film 24 is formed on the wall surface of the first portion 61, the aqueous filler 15 is more likely to flow preferentially along the inner wall of the first portion 61. This suppresses the formation of air bubbles between the inner wall of the first portion 61 and the filler, and further suppresses the filling 15 from trapping air bubbles. As a result, by filling with the filler 15 without trapping air bubbles, it becomes possible to form the discharge port forming member in a subsequent process without reducing flatness.

[0042] Furthermore, if only the wall surface of the first section 61 is hydrophilic, the filler 15 will be transferred to the first section 61 without remaining on the inclined surface 23, compared to the case where the inclined surface 23 of the inner wall of the second section 62 is also hydrophilic. In other words, the filling rate of the filler 15 is improved, and it becomes possible to fill with a smaller amount of filler, which leads to cost reduction.

[0043] Figure 5(e) shows the process of heat treatment after filling with the filler 15 and then removing the tape 25. Either a hot plate or an oven can be used for the heat treatment. The heating conditions can be adjusted as appropriate depending on the volatilization temperature of the solvent and the solid content concentration of the filler 15.

[0044] Figure 5(f) shows the process of forming a mold material 19 that will become a pressure chamber 12 communicating with the discharge port 11, and a discharge port forming member 9 having the discharge port 11, on the first surface 21 of the substrate 10. For the mold material 19, for example, a positive-type photosensitive resin can be used. For the method of forming the pressure chamber 12 communicating with the discharge port 11, general photolithography techniques can be used. The discharge port 11 is formed using the discharge port forming member 9. For example, a negative-type photosensitive epoxy resin can be used as the discharge port forming member 9. The discharge port forming member 9 is a member that also functions as the ceiling and side walls of the pressure chamber 12 communicating from the first liquid flow path 51 to the discharge port 11. Since the discharge port forming member 9 forms part of the pressure chamber 12 communicating with the discharge port 11 and is a member that comes into contact with the liquid, it is required to have high mechanical strength as a structural material, adhesion to the substrate 10, and liquid resistance (e.g., ink resistance). Furthermore, the discharge port forming member 9 is required to have sufficient resolution to pattern the fine pattern that will serve as the discharge port 11. The discharge port 11 can be formed using general photolithography techniques.

[0045] Figure 5(g) shows the process of removing the aqueous filler 15 and mold material 19. For example, pure water can be used as the material to remove the filler 15, but different removal materials can be used depending on the type of filler. For example, methyl lactate can be used as the material to remove the mold material 19. Next, the recording element substrate is completed by heat treatment.

[0046] As described above, even if the liquid supply port is formed perpendicular to the substrate during the manufacturing process of the recording element substrate, the filler 15 can be filled without trapping air bubbles, and a recording element substrate with high manufacturing precision can be manufactured.

[0047] Figure 6 is a cross-sectional view of the recording element substrate in this embodiment, taken from a direction where the inclined surface 23 of the second liquid channel 52 is visible, with the cross-section cut at the opening center of the first liquid channel 51 in the longitudinal direction of the recording element substrate. Multiple first liquid channels 51 are formed from the first surface 21 side relative to the second liquid channel 52. The longitudinal end shape of the second liquid channel 52 has multiple crystal planes formed as shown in the figure. This shape can change depending on the formation position of the lead hole 31 and the anisotropic etching time.

[0048] In this embodiment, a method for manufacturing a substrate 10 having a liquid supply port 13 having a first portion 61 and a second portion 62 has been described, but any substrate 10 such as this will suffice.

[0049] In the example shown above for the liquid supply port 13, the central axis of the first portion 61 and the central axis of the second portion 62 are misaligned, but the central axes do not necessarily have to be misaligned. When the central axes are misaligned, it becomes easier to transfer the filler to the inclined surface when filling it. This allows the filler 15 to flow more freely from the inner wall 61a connected to the inclined surface 23, and is expected to further reduce the possibility of the filler 15 trapping air bubbles. The central axis of the first portion 61 is the central axis that passes through the center of the first portion and extends in the direction from the second surface toward the first surface. Similarly, the central axis of the second portion 62 is the central axis that passes through the center of the second portion and extends in the direction from the second surface toward the first surface.

[0050] Furthermore, let D be the distance between the central axis of the first portion 61 and the central axis of the second portion 62 in the shorter direction. In this case, it is preferable to set the distance D as large as possible, taking into account the opening dimensions of both the first liquid flow path 51 and the second liquid flow path 52, so that the opening end of the first liquid flow path 51 does not exceed the opening end of the second liquid flow path 52.

[0051] Furthermore, in Figure 4(d), let α be the angle formed by the inclined surface 23 of the inner wall of the first portion 61 and the inner wall of the second portion 62. If α is too small, the angle of inclination becomes small, and the filler 15 does not flow along the inclination. If α is too large, the angle of inclination becomes too large, and air is trapped when the filler 15 is filled into the first liquid channel 51. Therefore, an angle α of about 110 to 160° is preferable.

[0052] Furthermore, in this invention, a hydrophilic film refers to one with a contact angle of 70° or less. In addition, to facilitate the flow of the filler 15, it is preferable that the contact angle of the hydrophilic film be 40° or less, which is generally considered to be more hydrophilic. Here, the contact angle in this invention refers to the dynamic receding contact angle of pure water on the surface of the member. Generally, the dynamic receding contact angle can be measured by the expansion and contraction method, which measures the behavior when liquid is injected or absorbed after a droplet has been placed on the surface of the member.

[0053] Furthermore, in this embodiment, a liquid channel wall protective film 18 is formed on the wall surface of the second liquid channel 52 in Figure 4(c), and a hydrophilic film is formed only on the first portion 61 in Figure 4(d). However, a hydrophilic film may also be formed on the inclined surface 23 of the inner wall of the second portion 62. In that case, the step of forming the liquid channel wall protective film 18 on the wall surface of the second liquid channel 52 may be omitted.

[0054] Alternatively, a hydrophilic film may be formed on the inner wall of the first portion 61, and a hydrophobic film may be formed on the inclined surface 23 of the inner wall of the second portion 62. In this case, when forming a hydrophilic film on the inner wall of the first portion 61, it is necessary to form a liquid channel wall protective film 18 on the inclined surface 23 of the inner wall of the second portion 62, and when forming a hydrophobic film on the inclined surface 23 of the inner wall of the second portion 62, it is necessary to form a liquid channel wall protective film 18 on the inner wall of the first portion 61. This makes it possible to form the desired film on either wall surface. Note that the formation of the hydrophilic film and the hydrophobic film may be performed in either order. However, since the formation of a hydrophilic film on the inner wall of the first portion 61 contributes more to the filling rate of the filler 15, it is preferable to form a hydrophilic film on the inclined surface 23 of the inner wall of the second portion 62 first, and then form a hydrophilic film on the inner wall of the first portion 61.

[0055] In the formation of the water-repellent film, similar to the formation of the hydrophilic film, the thickness of the liquid channel wall protective film 18 is preferably, for example, about 2 to 10 μm, but any thickness that can withstand being used as a mask when forming the water-repellent film is acceptable.

[0056] Water repellency means that when water droplets come into contact with a material, they do not spread and wet the material. Whether or not a water-repellent film is formed on a material can be determined by measuring the contact angle of the material's surface. In this invention, a water-repellent film refers to a film with a contact angle of 110° or more.

[0057] (modified version) A modified example of the first embodiment of the present invention will now be described. In the following description, only the parts that differ from the first embodiment will be described, and parts that are the same as the first embodiment will not be described.

[0058] The modified method for manufacturing a recording element substrate differs from the first embodiment in that it uses a resin dissolved in an oily solvent, a so-called oily filler. The oily filler can be any type that can be removed later. Furthermore, different materials can be used to remove the filler depending on the type of filler.

[0059] In the modified version, a water-repellent film is formed on at least the inner wall of the first portion 61. This allows the oily filler to more readily travel along the inner wall of the first portion 61 when an oily filler is used. In other words, it is possible to suppress the formation of air bubbles between the inner wall of the first portion 61 and the filler, and to suppress the filler from trapping air bubbles. Here, the contact angle of the water-repellent film in the present invention is 110° or more, but it is preferable that the contact angle of the inner wall of the first portion 61 be 150° or more so that the oily filler can more easily travel along the first portion 61.

[0060] Furthermore, in the modified example, a water-repellent film is formed on the first portion 61, but a water-repellent film may also be formed on the inclined surface 23 of the inner wall of the second portion 62. In that case, the step of forming a liquid channel wall protective film 18 on the wall surface of the second liquid channel 52 may not be necessary.

[0061] Furthermore, if a water-repellent film is formed only on the wall surface of the first section 61, the filler 15 will be transferred to the first section 61 without remaining on the inclined surface 23, compared to the case where a water-repellent film is also formed on the inclined surface 23 of the inner wall of the second section 62. In other words, the filling rate of the filler 15 is improved, and it becomes possible to fill with a smaller amount of filler, which leads to cost reduction.

[0062] Alternatively, a water-repellent film may be formed on the inner wall of the first portion 61, and a hydrophilic film may be formed on the inclined surface 23 of the inner wall of the second portion 62. In this case, in the step of forming a water-repellent film on the inner wall of the first portion 61, a liquid channel wall protective film 18 must be formed on the inclined surface 23 of the inner wall of the second portion 62, and in the step of forming a hydrophilic film on the inclined surface 23 of the inner wall of the second portion 62, a liquid channel wall protective film 18 must be formed on the inner wall of the first portion 61. This makes it possible to form the desired film on either wall surface. Note that the formation of the water-repellent film and the hydrophilic film can be performed in either order. However, since the formation of a water-repellent film on the inner wall of the first portion 61 contributes more to the filling rate of the oily filler, it is preferable to form the hydrophilic film on the second portion 62 first, and then form the water-repellent film on the inner wall of the first portion 61.

[0063] (Second embodiment) The configuration of the recording element substrate in the second embodiment of the present invention will be described. In the following description, only the parts that differ from the first embodiment will be described, and the parts that are the same as in the first embodiment will not be described.

[0064] Figure 7 is a cross-sectional view of the recording element substrate in the second embodiment. The recording element substrate of the second embodiment is a recording element substrate used in a so-called circulating type liquid discharge head, and differs from the first embodiment in that it has a liquid recovery port 14 corresponding to the liquid supply port 13 in the longitudinal direction of the substrate 10. Furthermore, the liquid recovery port 14 has a third liquid flow path 53 connected perpendicularly to the first surface 21 and a fourth liquid flow path 54 connected to the second surface 22. The third liquid flow path 53 also only needs to be connected substantially perpendicularly to the first surface, and it is assumed that it is connected perpendicularly at 90 ± 5°.

[0065] The third liquid channel 53 corresponds to the first liquid channel 51, and the fourth liquid channel 54 corresponds to the second liquid channel 52. The third liquid channel 53 is also referred to as the fourth section 64. Of the fourth liquid channel 54, the part with an inclined inner wall is also referred to as the fifth section 65, and the part that has one end connected to the inclined surface 28 of the inner wall of the fifth section 65 and the other end connected perpendicularly to the second surface 22 is also referred to as the sixth section. In other words, in Figure 7, the liquid recovery port 14 is composed of the fourth section 64, the fifth section 65, and the sixth section 66. Here, the inclined surface 28 of the inner wall of the fifth section 62 is inclined with respect to the inner wall of the fourth section 61 such that its width in the short direction (X direction) gradually increases toward the second surface 22.

[0066] In Figure 7, a liquid recovery port 14 having a sixth portion 66 is shown, but the liquid recovery port 14 in this embodiment does not necessarily have to have a sixth portion 66. That is, the liquid recovery port 14 may be formed only by the fourth portion 64 and the fifth portion 65. In other words, the structures of the third liquid flow path 53 and the fourth liquid flow path 54 are substantially the same as the structures of the first liquid flow path 51 and the second liquid flow path 52 in the first embodiment. Furthermore, the manufacturing methods of the third liquid flow path 53 and the fourth liquid flow path 54 are substantially the same as the manufacturing methods of the first liquid flow path 51 and the second liquid flow path 52 in the first embodiment, and are therefore omitted.

[0067] In the second embodiment, the liquid circulates in the following order: second liquid flow path 52, first liquid flow path 51, pressure chamber 12, third liquid flow path 53, and fourth liquid flow path 54.

[0068] In the manufacturing of the circulating recording element substrate, the inclined surfaces 23 and 28 cause the filler to flow downward from one side (inclined surface 23 or inclined surface 28) rather than flowing downward across the entire width of the liquid supply port (first portion 61 or fourth portion 64) as in the conventional example. As a result, similar to the first embodiment, the filler 15 flows from the inner wall 61a to 61b connected to the inclined surface 23, or from the inner wall 64a to 64b connected to the inclined surface 28, thus filling the substrate without trapping air bubbles.

[0069] Furthermore, when using an aqueous filler 15, a hydrophilic film is formed on the walls of the first portion 61 and the fourth portion 64, allowing the filler 15 to more readily propagate along the inner walls of each portion. This suppresses the formation of air bubbles between the inner walls of the first portion 61 and the fourth portion 64 and the filler, further suppressing the trapping of air bubbles by the filler 15. By filling with the filler 15 without trapping air bubbles, it becomes possible to form the discharge port forming member in a subsequent process without reducing flatness.

[0070] Furthermore, as in the first embodiment, when using an aqueous filler, a hydrophilic or hydrophobic film may be formed not only on the inner walls of the first portion 61 and the fourth portion 64, but also on the inclined surface 23 of the inner wall of the second portion 62 and the inclined surface 28 of the inner wall of the fifth portion 65.

[0071] Furthermore, similar to the modification of the first embodiment, when an oily filler is used, a water-repellent film is formed on the inner walls of the first portion 61 and the fourth portion 64. In this case, in addition to the first portion 61 and the fourth portion 64, a water-repellent or hydrophilic film may also be formed on the inclined surface 23 of the inner wall 62 of the second portion and the inclined surface 28 of the inner wall of the fifth portion 65.

[0072] Furthermore, because recording element substrates used in circulating liquid ejection heads have a large number of liquid channels, there is a concern that air bubbles may become trapped in the liquid channels, significantly affecting the flatness of the substrate surface. For this reason, it is preferable to use the configuration of the present invention for recording element substrates used in circulating liquid ejection heads.

[0073] If you want to reduce the distance between the first liquid channel 51 and the third liquid channel 53, it is preferable to arrange them so that they are mirror images of each other (left and right reversed), as shown in Figure 7. If L is the distance between the left and right second liquid channels in the short direction, it is preferable to set the distance L between the left and right second liquid channels appropriately, taking into account the distance between the left and right first liquid channels 51 and the Si strength.

[0074] In this embodiment as well, similar to the first embodiment, a substrate 10 equipped with a liquid recovery port 14 having a fourth portion 64 and a fifth portion 65 may be prepared.

[0075] However, the present invention is not limited to the embodiments described above. Various modifications and variations are possible without departing from the spirit and scope of the present invention. Based on the embodiments described above, examples of the present invention are shown below. [Examples]

[0076] Example 1 is shown below. Note that if the formation process and structure are the same as those of the embodiments described above, the explanation using figures will be omitted.

[0077] Figure 8 shows a top view and a cross-sectional view of the recording element substrate in Example 1. In Example 1, the recording element substrate is in a completed state, i.e., the state shown in Figure 2(b) in the first embodiment. The thickness of the substrate 10 was set to 725 μm.

[0078] Figure 8(a) is a top view of the recording element substrate as seen from the first surface 21 side. The configuration consists of a first liquid channel 51 formed in one row along the longitudinal direction of the recording element substrate, with discharge ports 11 formed in one row on each side along the longitudinal direction of the recording element substrate. In Example 1, the opening shape of the first liquid channel 51 is square, and the opening dimension is 100 μm. The distance between the ends of adjacent first liquid channels 51 is 50 μm. In the short direction, the distance from the opening center of the first liquid channel 51 to the opening center of the discharge port 11 is 130 μm. The opening shape and dimension of the discharge port 11 are circular with a diameter of 8 μm. In the longitudinal direction, the distance between adjacent discharge ports 11 is 40 μm. Note that the left and right rows of discharge ports do not necessarily have to be symmetrically arranged with respect to the first liquid channel 51; they may be arranged in different positions on the left and right sides, taking into consideration the discharge port size and discharge characteristics.

[0079] Figure 8(b) is a cross-sectional view of BB' in Figure 8(a). The opening dimension of the second liquid channel 52 in the short direction was set to 400 μm, and the opening dimension in the long direction was set to 20,000 μm. Regarding the position of the inclined surface 23 of the inner wall of the second portion 62, the apex of the inclination on the side closer to the first surface 21 was formed at a position 50 μm from the first surface 21 in the depth direction of the substrate. The angle between the inner wall of the first portion 61 and the inclined surface 23 of the inner wall of the second portion 62 was set to 125.3°. Next, the distance D between the opening center of the second liquid channel 52 and the opening center of the first liquid channel 51 in the short direction was set to 150 μm. [Examples]

[0080] Example 2 is shown below. Note that if the formation process and structure are the same as in the above-described embodiment, the explanation using diagrams will be omitted. Similarly, if the specific dimensions, positional relationships, etc., are the same as in Example 1, the description will be omitted.

[0081] Figure 9 shows the completed state of the recording element substrate in the second embodiment, i.e., the state shown in Figure 2(b) in the second embodiment. Figure 9(a) is a top view of the recording element substrate as seen from the first surface 21 side. The configuration consists of two rows of first liquid flow channels 51 formed along the longitudinal direction of the recording element substrate, with one row of discharge ports 11 formed between them along the longitudinal direction. In the short direction, it is preferable to appropriately set the distance between the opening centers of the left and right first liquid flow channels 51, taking into consideration the discharge port size and discharge characteristics. In Example 2, the distance in the short direction between the first liquid flow channel 51 and the third liquid flow channel 53 was set to 300 μm. The discharge port 11 was positioned at an intermediate position that divides the left and right first liquid flow channels 51 and the third liquid flow channel 53 into two equal parts. Note that the shape and dimensions of the left and right first liquid flow channels 51 may differ between the left and right rows. The discharge port 11 formed between the first liquid flow path 51 and the third liquid flow path 53 does not necessarily need to be positioned at an intermediate location that equally divides the space between the left and right flow paths, and can be adjusted as appropriate according to the discharge characteristics, etc.

[0082] Figure 9(b) is a cross-sectional view of CC' in Figure 9(a). Since the first liquid channel 51 and the third liquid channel 53 are formed in two rows on the left and right in the longitudinal direction, the second liquid channel 52 and the fourth liquid channel 54 are formed on the left and right sides respectively. The dimensions of each second liquid channel 52 and the distance D from the opening center of the first liquid channel 51 are the same as in Example 1. The dimensions of the third liquid channel 53 are the same as the first liquid channel 51 in Example 1, and the dimensions of the fourth liquid channel are the same as the dimensions of the second liquid channel in Example 1. The inclination directions of the inner walls of the left and right second sections 62 and the inner wall of the fifth section 65 are arranged so that they are mirror images (left and right inverted) of each other. In Example 2, the distance L between the second liquid channel 52 and the fourth liquid channel 54 is 200 μm. [Explanation of Symbols]

[0083] 1. Liquid dispensing head 2 Energy generating elements 3 bubbles 4. Oxide film 5. Airflow 9. Discharge port forming member 10 Silicon substrate 11 Discharge port 12 Pressure chamber 13 Liquid supply port 14 Liquid collection port 15 Filler 16 Surface protection film 17. Protective film on the back 18. Protective film for liquid channel walls 19 Profile material 20. Layer for improved adhesion 21 First side 22 Second side 23 Slope 24 Hydrophilic membrane 25 Tapes 26 Dispensing Needles 27 Side wall portion of the second liquid channel 28 Slope 31 Pilot hole 41 Recording element unit 42 enclosure units 43 cabinets 44 Recording element substrate 45 Recording element substrate 46 Flow channel forming member 47 Support plate 48 Electrical wiring board 49 terminals 51 First liquid channel 52 Second liquid channel 53 Third liquid channel 54. Fourth liquid channel 61 Part 1 62 Part 2 63 Part 3 64 Part 4 65 Part 5 66 Part 6

Claims

1. A discharge port forming member having a discharge port for discharging liquid and A substrate having a liquid supply port for supplying liquid to the discharge port, a first surface on which the discharge port forming member is placed, and a second surface which is the back surface of the first surface, In a recording element substrate comprising, The liquid supply port has a first portion connected perpendicularly to the first surface and a second portion connected to the first portion. The inner wall of the second portion is provided with an inclined surface that is inclined with respect to the inner wall of the first portion such that the width of the second portion gradually increases toward the second surface. A hydrophilic film is formed on the inner wall of the first portion. A recording element substrate characterized in that a water-repellent film is formed on the inclined surface of the inner wall of the second portion.

2. The recording element substrate according to claim 1, wherein the contact angle of the hydrophilic film formed on the inner wall of the first portion is 40° or less.

3. The system further includes a liquid recovery port for recovering liquid that was not discharged from the aforementioned discharge port, The liquid recovery port has a fourth portion connected perpendicularly to the first surface, a fifth portion connected to the fourth portion, and a sixth portion connected to the fifth portion. The inner wall of the fifth portion has an inclined surface that is inclined with respect to the inner wall of the fourth portion such that the width of the fifth portion gradually increases toward the second surface. The sixth portion has one end connected to the inclined surface of the inner wall of the fifth portion, and the other end connected perpendicularly to the second surface. The recording element substrate according to claim 1 or 2, wherein a hydrophilic film is formed on the inner wall of at least the fourth portion.

4. The recording element substrate according to claim 3, wherein a hydrophilic film is formed on the inclined surface of the inner wall of the fifth portion.

5. The recording element substrate according to claim 3, wherein a water-repellent film is formed on the inclined surface of the inner wall of the fifth portion.

6. A discharge port forming member having a discharge port for discharging liquid and A substrate having a liquid supply port for supplying liquid to the discharge port, a first surface on which the discharge port forming member is placed, and a second surface which is the back surface of the first surface, In a recording element substrate comprising, The liquid supply port has a first portion connected perpendicularly to the first surface and a second portion connected to the first portion. The inner wall of the second portion is provided with an inclined surface that is inclined with respect to the inner wall of the first portion such that the width of the second portion gradually increases toward the second surface. A water-repellent film is formed on the inner wall of the first portion. A recording element substrate characterized in that a hydrophilic film is formed on the inclined surface of the inner wall of the second portion.

7. The recording element substrate according to claim 3, wherein the contact angle of the water-repellent film formed on the inner wall of the first portion is 150° or more.

8. The system further includes a liquid recovery port for recovering liquid that was not discharged from the aforementioned discharge port, The liquid recovery port has a fourth portion connected perpendicularly to the first surface, a fifth portion connected to the fourth portion, and a sixth portion connected to the fifth portion. The inner wall of the fifth portion has an inclined surface that is inclined with respect to the inner wall of the fourth portion such that the width of the fifth portion gradually increases toward the second surface. The sixth portion has one end connected to the inclined surface of the inner wall of the fifth portion, and the other end connected perpendicularly to the second surface. The recording element substrate according to claim 6 or 7, wherein a water-repellent film is formed on the inner wall of at least the fourth portion.

9. The recording element substrate according to claim 8, wherein a water-repellent film is further formed on the inclined surface of the inner wall of the fifth portion.

10. The recording element substrate according to claim 8, wherein a hydrophilic film is further formed on the inclined surface of the inner wall of the fifth portion.

11. The angle between the inclined surfaces of the inner wall of the first part and the inner wall of the second part is 110 to 160 A recording element substrate according to any one of claims 1 to 10, wherein the degree is °.

12. The recording element substrate according to any one of claims 1 to 11, wherein, in the short-side direction of the substrate on the first surface, the central axis of the first portion and the central axis of the second portion are offset.

13. A recording element substrate according to any one of claims 3 to 5 or any one of claims 8 to 10, wherein, in the short-side direction of the substrate on the first surface, the central axis of the fourth portion and the central axis of the fifth portion are offset.

14. A discharge port forming member having a discharge port for discharging liquid and A substrate having a liquid supply port for supplying liquid to the discharge port, a first surface on which the discharge port forming member is placed, and a second surface which is the back surface of the first surface, In a method for manufacturing a liquid dispensing head equipped with, A step of preparing a substrate having a liquid supply port having a first portion connected perpendicularly to the first surface and a second portion connected to the first portion, wherein the inner wall of the second portion has an inclined surface that is inclined with respect to the inner wall of the first portion such that the width of the second portion gradually increases toward the second surface, A step of forming a hydrophilic film on the inner wall of at least the first portion, The steps include: attaching tape to the first surface of the substrate having the liquid supply port; The process involves dripping an aqueous filler onto the inclined surface of the inner wall of the second portion, and filling the first portion with the aqueous filler. The step of removing the aforementioned tape, The process involves forming the discharge port forming member on the first surface, A step of removing the aqueous filler, A method for manufacturing a recording element substrate, characterized by having the following features.

15. The method for manufacturing a recording element substrate according to claim 14, wherein the step of forming the hydrophilic film is to further form a hydrophilic film on the inclined surface of the inner wall of the second portion.

16. The method for manufacturing a recording element substrate according to claim 14, further comprising the step of forming a water-repellent film on the inclined surface of the inner wall of the second portion.

Images