JP2024040783A - Liquid ejection head and manufacturing method therefor - Google Patents

Abstract

To provide a liquid ejection head that prevents creeping up of a filler, while having a tapered liquid passage, and to provide a manufacturing method therefor that prevents creeping up of a filler along the liquid ejection head.SOLUTION: In a liquid ejection head including a substrate 10 having a first surface 21, a second surface 22, and a liquid passage 53 allowing communication between the first surface and the second surface, the liquid passage has a first liquid passage 13, a second liquid passage 14, and a connection surface 61 to which the first liquid passage and the second liquid passage are connected; the connection surface has a projection 23 projecting in a direction of the second surface; and the projection has a tapered top 65 and includes a first slope 63 inclined from the top toward the second liquid passage and a second slope 64 inclined toward a side wall of the first liquid passage adjacent to the projection.SELECTED DRAWING: Figure 4

Description

The present invention relates to a liquid ejection head and a method for manufacturing the same.

There are liquid ejecting devices such as inkjet printers that eject liquid to record images, characters, etc. on a recording medium such as paper. The liquid ejection device has a liquid ejection head that ejects liquid. Further, the liquid ejection head includes an ejection port forming member having an ejection port for ejecting liquid, and a substrate on which the ejection port forming member is placed. Further, the substrate is formed with an energy generating element that generates energy for ejecting liquid from the ejection port, a liquid channel for supplying liquid to the ejection port, and the like.

As a method for manufacturing such a liquid ejection head, for example, there is a method described in Patent Document 1. In Patent Document 1, a liquid ejection head is manufactured by forming a liquid flow path on a substrate, filling the opening of the liquid flow path with a filler, flattening the substrate surface, and then forming an ejection port forming member. In this manufacturing method, a tape is pasted on the opening of the liquid channel, and then a filler is filled into the liquid channel from a dispense needle using a dispensing device. In such a manufacturing method, the filling performance (flatness) of the filler into the liquid flow path is important because the filling performance of the filler affects the flatness of the substrate surface and also affects the accuracy of the ejection port that is subsequently formed. becomes.

Japanese Patent Application Publication No. 2002-326363

However, when manufacturing a liquid ejection head having a tapered liquid flow path using the method described in Patent Document 1, for example, concerns arise in the filler filling process. If the filler is applied while bringing the dispense needle close to the surface to which the filler is to be applied, there is a risk that the applied filler will creep up the dispense needle due to surface tension. On the other hand, if you release the dispense needle and apply the filler to the surface you want to apply the filler to, the filler discharged from the dispense needle will spread and there is a risk that the filler will creep up on the side wall of the surface you want to apply the filler to. . If such creeping of the filler occurs, there is a risk that the filling performance of the opening of the liquid flow path will be reduced.

In view of the above problems, the present invention provides a liquid ejection head that suppresses creeping up of filler while having a tapered liquid flow path, and a manufacturing method that suppresses creeping up of filler in the liquid ejection head.

In order to solve the above problems, the present invention provides an ejection port for ejecting liquid, a first surface on the side where the ejection port is formed, a second surface that is the back surface of the first surface, and a second surface that is the back surface of the first surface. In a liquid ejection head comprising: a substrate having a liquid channel communicating between a first surface and the second surface, the liquid channel communicates with the first liquid a flow path, a second liquid flow path connected to the first surface and communicating with the first liquid flow path, and the first liquid flow path and the second liquid flow path are connected. the second liquid flow path has a connection surface, the opening length of the second liquid flow path in the lateral direction of the substrate is shorter than the opening length of the first liquid flow path; a convex portion protruding in the direction of the surface, the convex portion having a tapered apex, a first slope sloped from the apex toward the second liquid flow path, and the convex portion The liquid flow path may include a second slope inclined toward a side wall of the first liquid flow path adjacent to the first liquid flow path.

According to the present invention, it is possible to provide a liquid ejection head that suppresses creeping up of filler while having a tapered liquid flow path, and a manufacturing method that suppresses creeping up of filler in the liquid ejection head.

FIG. 3 is an external perspective view of a liquid ejection head. A schematic diagram of a recording element substrate (liquid ejection head). 1 is a flowchart showing a method for manufacturing a liquid ejection head. FIG. 3 is a cross-sectional view showing a method of manufacturing a liquid ejection head. FIG. 3 is a cross-sectional view showing a method of forming a liquid flow path in a liquid ejection head. FIG. 3 is a cross-sectional view of a liquid ejection head showing a filler filling method. FIG. 3 is a schematic diagram of a liquid ejection head in a second embodiment. FIG. 3 is a schematic diagram of a liquid ejection head in a third embodiment (Example 3). 1 is a schematic diagram of a liquid ejection head in Example 1. FIG. FIG. 3 is a schematic diagram of a liquid ejection head in Example 2. FIG. 4 is a schematic diagram of a liquid ejection head in Example 4. FIG. 7 is a schematic diagram showing a process of filling a filler into a liquid ejection head in a comparative example. FIG. 3 is a schematic diagram in which a flow path is blocked by air bubbles in a liquid ejection head of a comparative example.

Embodiments of the present disclosure will be described below with reference to the drawings. Note that the following embodiments do not limit the matters of the present invention, and not all combinations of features described in the present embodiments are essential to the solution of the present invention. Note that the same reference numbers are given to the same components.

The method of processing a silicon substrate according to the present invention is suitable for forming a liquid flow path of a liquid ejection head in a silicon substrate in the manufacturing process of a structure including a silicon substrate, particularly a device such as a liquid ejection head. It is something. In the following, an example will be described in which the method for processing a liquid flow path according to the present invention is applied to manufacturing a substrate on which an energy generating element is provided in a liquid ejection head, that is, a recording element substrate (liquid ejection head). Of course, the liquid flow path processing method based on the present disclosure is not only used for manufacturing liquid ejection heads, but can also be used for manufacturing and processing other structures using silicon substrates. In addition, when applying the liquid flow path processing method based on the present invention to manufacturing a liquid ejection head, the crystal orientation of the surface of the silicon substrate is the (100) plane, or the crystal orientation of the surface is the (100) plane. It is preferable to use surfaces that are equivalent. In this case, it is preferable to use a substrate having a thickness of about 580 to 750 μm.

(First embodiment)
(Liquid discharge head)
FIG. 1(a) is a perspective view showing the liquid ejection head 1 of this embodiment, and FIG. 1(b) is an exploded perspective view showing each member of the liquid ejection head 1 shown in FIG. 1(a). It is a diagram. As shown in FIG. 1B, the liquid ejection head 1 of this embodiment mainly includes a recording element unit 41 and a housing unit 42. As shown in FIG.

The recording element unit 41 includes recording element substrates 44 and 45 having ejection ports 11 (FIG. 2) for ejecting liquid, an electric wiring board 48 for supplying power to the recording element substrates 44 and 45, and a recording element substrate 44 and 45. It is mainly composed of a support plate 47 that supports 45.

The housing unit 42 includes a housing 43 to which a liquid container (not shown) that stores liquid to be supplied to the discharge port 11 (FIG. 2) is connected, and a housing 43 that supplies liquid from the liquid container (not shown) to the discharge port 11. It is mainly composed of a flow path forming member 46 in which a flow path for supplying water is formed.

(Recording element substrate)
The recording element substrate 44 will be explained using FIG. 2. FIG. 2A is a schematic diagram of the recording element substrate 44. Since liquid is ejected from the recording element substrate 44, the recording element substrate itself is also referred to as a liquid ejection head. As shown in FIG. 2A, the recording element substrate 44 includes a substrate 10 made of silicon or the like and an ejection port forming member 9. An energy generating element 2 that generates energy for ejecting liquid from the ejection port 11 is formed on the substrate 10 .

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

The recording element substrate 44 is electrically connected to the electrical wiring board 48 via terminals 49 . The energy generating element 2 receives an electrical signal from the electrical wiring board 48 and generates ejection energy for ejecting a liquid such as ink.

The discharge port forming member 9 forms a discharge port 11 for discharging liquid and a pressure chamber 12 communicating with the discharge port 11. A liquid flow path 53 communicating with the discharge port 11 is formed in the substrate 10, and the liquid flow path is a through hole that penetrates the substrate 10. In this embodiment, a liquid supply channel is formed as the liquid channel 53. Liquid is supplied to the pressure chamber 12 from the liquid supply channel. In this embodiment, the liquid flow path 53 will be explained based on a liquid supply flow path, but the liquid flow path 53 may be a liquid recovery flow path that is a flow path for recovering liquid that has not been ejected from the ejection port. Good too. The substrate 10 has a rectangular shape extending in the direction in which the energy generating elements 2 are arranged. direction.

FIG. 2(b) is a sectional view taken along line AA' in FIG. 2(a) of the recording element substrate (liquid ejection head) in the first embodiment. Furthermore, in the following description, a cross-sectional view of the recording element substrate 44 (liquid ejection head) represents a cross-sectional view taken along line AA' in FIG. 2(a). Of the two surfaces of the substrate 10, the side on which the ejection ports are formed is called a first surface 21, and the back surface of the first surface 21 is called a second surface 22. Below, the features of the liquid ejection head in this embodiment shown in FIG. 2(b) and the manufacturing method thereof will be described in detail.

(Method for manufacturing liquid ejection head)
FIG. 3 is a flowchart illustrating each step of the method for manufacturing a liquid ejection head in this embodiment. Each process in the flowchart will be explained below in association with a method for manufacturing a liquid ejection head.

FIG. 4 is a cross-sectional view illustrating a method of manufacturing a liquid ejection head in this embodiment. FIG. 4A shows a step of forming the adhesion improving layer 20 on the liquid ejection head substrate. The adhesion improving layer 20 is for improving the adhesion between the substrate 10 and the ejection port forming member 9 that will be formed later. As the adhesion improving layer 20, for example, polyetheramide can be used. A method for forming the adhesion improving layer 20 includes, for example, a method of forming it by a general photolithography technique using a positive type photosensitive resin as a mask. Alternatively, it is also possible to use a photosensitive epoxy resin as the adhesion improving layer 20. The thickness of the adhesion improving layer 20 is preferably about 1 to 5 μm.

The liquid ejection head of this embodiment includes a substrate 10 on which energy generating elements 2 that generate energy for ejecting liquid are formed in two rows at a predetermined pitch. An energy generating element is provided only on one surface of the substrate 10 constituting the liquid ejection head. Here, of the two surfaces of the substrate 10, the surface on which the energy generating element 2 is provided (the surface on the side where the ejection port is formed) is the first surface 21. In this embodiment, a heating resistor element is used as the energy generating element 2, but the present invention is not limited to this. That is, a discharge method in which liquid is discharged using a piezoelectric element (piezo) as an energy generating element, or another discharge method can also be adopted.

It is preferable that an oxide film 4 made of, for example, SiO ₂ is provided on the entire or part of the first surface 21 . Further, it is preferable that an oxide film 4 made of SiO ₂ , for example, is provided on the entire surface or a part of the second surface 22 . Furthermore, in addition to the oxide film 4, various inorganic films may be provided as necessary.

FIG. 4B is a schematic diagram of a liquid ejection head in which a liquid channel 53 is formed in the substrate 10 and the second liquid channel 14 is filled with the filler 15. The method for forming the liquid flow path and the method for filling the filler 15 will be described in detail later.

The liquid flow path 53 communicating with the discharge port includes the first liquid flow path 13 connected to the second surface 22 and the first liquid flow path 53 connected to the first surface 21 and communicating with the first liquid flow path 13. It has two liquid flow paths 14. In this embodiment, since the liquid channel 53 is a liquid supply channel, liquid is supplied from the first liquid channel 13 to the second liquid channel 14, and from the second liquid channel 14 to the pressure chamber. The liquid is supplied to the discharge port 11 through the discharge port 12 .

Here, in this embodiment, the first liquid flow path 13 extends in the longitudinal direction of the substrate 10, and a plurality of second liquid flow paths 14 are formed at intervals in the longitudinal direction. . That is, the first liquid channel 13 supplies liquid to the plurality of second liquid channels 14, and the liquid is supplied from the plurality of second liquid channels 14 to the pressure chamber 12. In other words, the first liquid channel 13 is a common supply channel, and the second liquid channel 14 serves as an individual supply channel. Note that a plurality of first liquid channels 13 may be formed at intervals in the longitudinal direction like the second liquid channels 14, and the second liquid channel 14 may be formed as the first liquid channel. 13 may extend in the longitudinal direction. That is, it is sufficient that the second liquid flow path 14 is tapered compared to the first liquid flow path 13. In other words, the opening length of the second liquid flow path 14 in the lateral direction of the substrate may be shorter than the opening length of the first liquid flow path 13.

Further, in this embodiment, the liquid flow path 53 is described as a liquid supply flow path, but the liquid flow path 53 is a liquid recovery flow path that is a flow path for recovering liquid that has not been ejected from the ejection port. It's okay. In that case, the liquid that is not discharged from the discharge port 11 passes through the pressure chamber 12 and is collected into the second liquid flow path, and further collected from the second liquid flow path into the first liquid flow path.

Further, the connecting surface 61 where the first liquid flow path 13 and the second liquid flow path 14 are connected has a convex portion 23 that projects in the direction of the second surface 22 . Further, the convex portion 23 has a tapered top portion 65, and a first slope 63 that slopes from the top portion 65 toward the second liquid flow path, and a side wall of the first flow path adjacent to the convex portion. It includes a second slope 64 that slopes toward the front. Details of the convex portion 23 will be explained later.

As the filler 15, a resin dissolved in an appropriate solvent can be used as long as it is removable regardless of whether it is hydrophilic or lipophilic. In addition, when using an organic solvent to remove the mold material 19 (FIG. 4(c)) as described later, it is preferable to use an aqueous filler that is not dissolved by the organic solvent. As the aqueous filler, for example, a filler prepared by dissolving PVA (polyvinyl alcohol) in pure water can be used.

FIG. 4C shows a step of patterning the discharge port forming member 9 and the mold material 19 that will become the pressure chamber 12 communicating with the discharge port on the first surface 21 of the substrate 10. A discharge port 11 is formed by the discharge port forming member 9 . As the discharge port forming member 9, for example, a negative type photosensitive epoxy resin can be used. The discharge port forming member 9 is a member that also functions as a ceiling, a side wall, etc. of the pressure chamber 12. Since the ejection port forming member 9 is a member that comes into contact with liquid, the ejection port forming member 9 has high mechanical strength as a structural material, adhesion to the underlying substrate 10, and liquid resistance (for example, ink resistance). ) is preferably used. Furthermore, it is preferable that the ejection port forming member 9 has resolution for patterning a fine pattern as the ejection port 11. The ejection port 11 can be formed using a general photolithography technique.

The pressure chamber 12 is a liquid chamber in which the pressure generated by the energy generating element 2 acts on the liquid. When pressure is applied to the liquid in the pressure chamber 12, the liquid is discharged from the discharge port 11. The pressure chamber 12 can be formed using a general photolithography technique.

The distance (height) from the first surface 21 to the surface of the ejection port 11 is preferably about 10 to 100 μm. Further, the shape of the ejection port may be various shapes such as a perfect circle or an ellipse depending on the ejection characteristics. Regarding the dimensions, various dimensions are possible depending on the ejection characteristics. The dimensions are preferably such that the cross-sectional area of the ejection port is, for example, about 40 to 450 μm ² .

FIG. 4(d) shows the step of removing the mold material 19 and filler 15. Note that this step corresponds to FIG. 3(e). Filler 15 is removed after mold material 19 is removed. As the material for removing the mold material 19, for example, methyl lactate can be used. When using a filler prepared by dissolving PVA (polyvinyl alcohol) in pure water as the filler 15, pure water can be used as the filler removal material. Note that the material for removing the filler depends on the type of filler and is not limited to this, but any material may be used as long as it is capable of removing the filler and does not dissolve other members of the liquid ejection head. Next, a baking process is performed to complete the liquid ejection head 44.

The above is the manufacturing process of the liquid ejection head in this embodiment.

(Method for forming liquid flow path)
Next, in the method for manufacturing the liquid ejection head described in FIG. 4, details of the process of forming the liquid flow path 53 will be described with reference to FIG.

FIG. 5A shows a step in which laser processing is performed from the second surface 22 side of the substrate 10 in order to form the first liquid flow path 13. First, the substrate backside protective film 17 is patterned on the second surface 22 except for the area where the first liquid flow path 13 is desired to be opened. The substrate backside protective film 17 can be formed, for example, by a process similar to the method of patterning the adhesion improving layer 20 described above. Next, by removing the oxide film 4 in the area not protected by the substrate backside protective film 17, an opening area for opening the first liquid flow path 13 is formed. As a method for removing the oxide film 4, there is, for example, wet treatment using buffered hydrofluoric acid. The opening length of the first liquid flow path 13 in the lateral direction is preferably about 200 to 1500 μm. It is preferable that the opening size in the longitudinal direction is appropriately set depending on the number of discharge ports 11 to be formed. For example, the opening dimension in the longitudinal direction is preferably about 5,000 to 40,000 μm.

Next, a plurality of unpierced holes (hereinafter referred to as guide holes 31) having a predetermined depth are machined using a laser from the second surface 22 side in the region to be opened. As described above, the connecting surface 61 where the first liquid flow path 13 and the second liquid flow path 14 connect has the convex portion 23 that projects in the direction of the second surface. Therefore, as shown in FIG. 5(a), it is necessary to process the guide hole 31 by changing its depth depending on the desired shape. The pattern and depth of the guide hole 31 can be adjusted as appropriate depending on the desired shape and opening size. For example, when the laser diameter of the guide hole 31 is about 30 μm, the laser pitch is preferably about 30 to 400 μm in both the long and short directions so that adjacent guide holes 31 do not interfere with each other. The laser depth when forming the convex portion 23 is preferably, for example, 370 to 650 μm when the thickness of the substrate 10 is about 725 μm, and for the connection surface 61, about 350 to 670 μm. Further, the number of lasers in the lateral direction is preferably about 1 to 5.

FIG. 5(b) shows a step of forming the first liquid channel 13 by anisotropic etching. Examples of the etching solution used for anisotropic etching include strong alkaline solutions such as TMAH and KOH. In the anisotropic etching, the etching liquid permeates into the guide holes 31, and etching progresses along the guide holes. Eventually, the guide holes 31 connect with each other, thereby forming the first liquid flow path 13. If the etching time is too long, the etching will progress and the convex portion 23 will not be formed, so the etching time needs to be adjusted as appropriate by considering the pattern and depth of the pilot hole, the desired slope shape, and the opening size. . The etching time is preferably about 1 to 4 hours, for example. The position where the connection surface 61 is formed is preferably about 30 to 300 μm from the first surface 21 in the depth direction of the substrate. It is desirable that the convex portion 23 has a shape that does not hinder the filling of the filler. For example, if the opening length of the first liquid flow path in the transverse direction of the substrate is a, and the length of the convex portion is w, it is preferable that the relationship a/4<w<a/2 holds. . Here, the length w of the convex portion represents the distance between each of the first slope 63 and the second slope 64 and the portion to which the connection surface 61 connects. Further, if the depth of the first liquid flow path is b, and the height from the connecting surface 61 to the top 65 of the convex portion is h, it is preferable that the relationship b/20<h<b holds. Further, the shape of the convex portion 23 may have rounded corners or may have a flat portion. If there is a flat part, it is preferable that the length of the flat part is smaller than the diameter of the droplet of the filler to be discharged in order to suppress the filler from creeping up to the dispensing needle.

Further, as shown in FIG. 5(b), the convex portion 23 has a first slope 63 that slopes toward the second liquid flow path, and a side wall of the first liquid flow path that is adjacent to the convex portion. It is formed from an inclined second slope 64. Details of the convex portion 23 will be described later.

FIG. 5(c) shows the step of forming the second liquid flow path 14. First, on the first surface 21, a surface protection film 16 is patterned and formed in a region other than the region where the second liquid flow path 14 is desired to be opened using a method similar to that shown in FIG. 5(a). The opening shape of the second liquid flow path 14 is preferably rectangular, but may be circular or elliptical. Further, in the case of a quadrilateral, the corners may be rounded. The opening size of the second liquid flow path 14 is preferably about 30 to 200 μm. In this embodiment, the plurality of second liquid channels 14 are preferably arranged at regular intervals, and the distance between the ends of adjacent second liquid channels 14 is approximately 30 to 200 μm. is preferred.

Next, the second liquid flow path 14 is formed by dry etching from the first surface 21 side. As a method for forming the second liquid flow path 14, in addition to dry etching, formation by laser processing is also possible. The depth of the second liquid channel 14 is already determined based on the thickness of the substrate 10 and the shape of the already formed first liquid channel 13, and is preferably about 30 to 300 μm.

FIG. 5(d) shows a step of removing the front protective film 16 and the back protective film 17. As for the removal method, it is possible to remove the used positive photosensitive resin using a stripping liquid that can remove it.

Through the above steps, the flow path structure of the liquid ejection head of this embodiment can be formed. Although the method for forming the flow path structure of the liquid ejection head of this embodiment has been described, in the method of manufacturing the liquid ejection head of this embodiment, the substrate shown in FIG. 5(d) may be prepared (see FIG. (a)). That is, the substrate 10 shown in FIG. 5(d) may be prepared and the liquid ejection head may be manufactured by the method described above.

(Method of filling filler)
Next, details of the process of filling the filler 15 into the first liquid flow path 13 and the second liquid flow path 14 formed by the method described above will be explained with reference to FIG. Note that it is sufficient that the filler 15 fills the opening on the first surface 21 side of the second liquid flow path 14 flatly, and it is not necessary that the entire second liquid flow path 14 is filled with the filler 15. There's no need. Further, the first liquid channel 13 does not necessarily need to be filled with the filler 15 either. Note that this step corresponds to FIG. 3(c).

In FIG. 6(a), a tape 25 is placed on the first surface 21 to prevent the filler 15 from leaking when filling the first liquid flow path 13 and the second liquid flow path 14 with the filler 15. It shows the pasting process. Note that this step corresponds to FIG. 3(b). Further, it is not necessary to apply the tape 25 to the entire surface of the first surface 21, and it is sufficient to apply the tape to the opening of the second liquid flow path so that the filler 15 does not leak out from the opening. The tape 25 is preferably made of a material that can be attached by absorbing the level difference on the first surface 21 so that the filler 15 does not leak out. Further, if it is necessary to volatilize the solvent by baking after filling the filler 15, it is preferable to use a material that can withstand the baking temperature. Further, since the adhesive layer comes into contact with the filler 15, it is preferable that the adhesive layer is resistant to the solvent of the filler.

FIG. 6(b) is a schematic diagram showing how the second liquid channel 14 is filled with the filler 15. As a method for filling the filler 15, for example, a filling method using a dispensing device equipped with a dispensing needle 26 that can be inserted into the first liquid flow path 13 can be mentioned. When the opening length of the first liquid flow path 13 in the transverse direction of the substrate is about 400 μm, the maximum width of the needle diameter (outer diameter) is preferably about 350 μm or less. As the device used for filling the filler, a dispensing device equipped with a dispensing needle is preferable from the viewpoint of filling the minute flow path of the liquid ejection head, but is not limited thereto. That is, any device or instrument that can fill a minute channel with a filler may be used.

The idea of this embodiment is that by dropping the filler 15 on the top 65 of the convex portion 23, the filler 15 flows on the first slope 63 and the second slope 64, and flows into the second liquid flow path 14. It is filled with a filler. Therefore, when filling, the filler 15 is dispensed from directly above the convex part 23 so that the filler 15 touches the top part 65 of the convex part 23. Furthermore, if the filler touches the side wall of the first liquid flow path 13 before touching the convex portion 23, the filler creeps up the wall surface, reducing the filling performance of the second liquid flow path. There is a fear. Furthermore, if the tip of the dispense needle 26 comes into contact with the convex portion 23, there is a risk that the tip of the dispense needle 26 will be damaged. Therefore, the distance from the tip of the dispensing needle 26 to the apex 65 is preferably such that the filler 15 comes into contact with the apex 65 and the dispensing needle 26 and the apex 65 do not come into contact with each other. For example, when the convex portion 23 has a transverse dimension of 150 μm, a height of 100 μm, and a dispensing needle inner diameter of 25 μm, the distance from the tip of the dispensing needle 26 to the top 65 is preferably about 10 to 50 μm.

6(c) and 6(d) show how the second liquid channel 14 is filled with the filler 15. First, as shown in FIG. 6(c), the filler 15 applied to the top of the convex portion 23 is applied to the convex portion 23 because the convex portion 23 is formed from the first slope 63 and the second slope 64. Remaining on the top portion 65 of the portion 23 is suppressed. That is, the filler 15 flows on the first slope 63 and the second slope 64. Therefore, the distance between the tip of the dispensing needle 26 and the top portion 65 can be reduced. That is, even when the filler is applied while the distance between the tip of the dispense needle 26 and the top portion 65 is close, the creep of the filler 15 to the dispense needle 26 is suppressed. Furthermore, since the filler 15 can be applied by moving the dispense needle 26 closer to the top 65, it is possible to reduce the possibility that the filler will creep up the inner wall of the liquid flow path. Therefore, in the liquid ejection head of this embodiment, although it has a tapered liquid flow path, it is possible to suppress the filler from creeping up to the dispensing needle 26 and to the wall surface of the liquid flow path. Note that the steps in FIGS. 6(b) to 6(d) correspond to FIG. 3(c).

Further, in the liquid ejection head of the present embodiment, since the convex portion 23 has the first slope 63 that slopes toward the second liquid flow path 14, the filling applied to the top portion 65 of the convex portion 23 The agent 15 flows on the first slope 63 and fills the second liquid channel 14 . Therefore, filling the second liquid flow path 14 with the filler 15 so as to cover it is suppressed, so it is possible to reduce the possibility that the filler entraps air bubbles.

Note that if the inclination angle α of the first slope 63 with respect to the connection surface 61 is too small, the filler 15 will flow on the slope and it will be difficult to fill the second liquid flow path 14. Furthermore, if the inclination angle α of the first slope 63 with respect to the connection surface 61 is too large, the filler will trap air bubbles for the above-mentioned reason. Therefore, it is preferable that the inclination angle α of the first slope with respect to the connecting surface 61 is 20° to 70°.

Furthermore, if the inclination angle β of the second slope 64 with respect to the connecting surface 61 is too small, the filler will remain at the apex of the convex portion 23, making it easy for the filler to creep up. On the other hand, if the inclination angle β of the second slope 64 with respect to the connecting surface 61 is too large, some of the filler attached to the apex of the convex portion 23 will flow through the first slope 63 and the second liquid flow path 14 will flow. The amount of filler to be filled will be reduced. Therefore, the inclination angle β with respect to the connection surface 61 is preferably 20° to 70°.

Furthermore, from the viewpoint of filling the second liquid flow path with the filler, it is preferable that the amount of filler flowing on the first slope 63 is larger than the amount of filler flowing on the second slope 64. That is, it is preferable that the inclination angle α of the first slope with respect to the connection surface 61 is larger than the inclination angle β of the second slope with respect to the connection surface 61.

Furthermore, as shown in FIGS. 10(b) and 10(c), which will be described later, a plurality of convex portions 23 may be formed on one side of the second liquid flow path 14 in the lateral direction. In order not to reduce the amount of filler that spreads to the second liquid flow path 14, it is preferable that among the plurality of projections, the one closer to the second liquid flow path is smaller.

Further, in order to make it easier for the filler 15 to flow from the first slope 63 to the second liquid flow path 14, the inner wall of the second liquid flow path may be subjected to surface treatment according to the material properties of the filler. is preferred.

When using an aqueous filler, it is preferable that a hydrophilic film is formed on the inner wall of the second liquid flow path 14. As a result, the second liquid flow path has higher hydrophilicity than the first slope 63. That is, since the hydrophilic filler spreads easily from the first slope 63 to the second liquid channel, the filling property of the second liquid channel is improved. Here, the hydrophilic film in this embodiment refers to a film having a contact angle with respect to pure water of 70° or less. Furthermore, it is preferable that the contact angle of the hydrophilic film with pure water is 40° or less. The greater the hydrophilicity of the second liquid channel 14 is, the more the filling property of the second liquid channel can be expected to be improved. Here, the contact angle in this embodiment represents the dynamic receding contact angle of pure water on the surface of the member. In general, the dynamic receding contact angle can be measured by the expansion-contraction method, which measures the behavior of a droplet when it is injected or absorbed after landing on the surface of a member.

When using an oil-based filler, it is preferable that a lipophilic film is formed on the inner wall of the second liquid flow path 14. As a result, the second liquid flow path has higher lipophilicity than the first slope 63. That is, as in the case of a hydrophilic filler, the oil-based filler spreads easily from the first slope 63 to the second liquid channel, so that the filling property of the second liquid channel is improved. Here, the lipophilic film in this embodiment refers to a film having a contact angle with respect to pure water of 110° or more. Furthermore, it is preferable that the contact angle of the lipophilic film with pure water is 150° or more. The greater the lipophilicity of the second liquid channel 14, the better the filling property of the second liquid channel can be expected.

Furthermore, when forming a hydrophilic film or a lipophilic film in the second liquid flow path in the method for manufacturing a liquid ejection head, it is necessary to form the film before the step of filling the filler. Note that the method for forming the hydrophilic film and the lipophilic film is not particularly limited, and any method may be used.

FIG. 6(e) shows a step of baking after filling the filler 15 and removing the tape 25. Note that this step corresponds to FIG. 3(d). For baking, either a hot plate or an oven can be used. The baking conditions can be adjusted as appropriate depending on the volatilization temperature of the solvent and the solid content concentration of the filler. The tape 25 can be removed by peeling. Alternatively, the tape 25 may be removed by dissolving it using a liquid that dissolves only the tape 25.

As described above, even if the liquid channel has a tapered shape (second liquid channel), creeping up of the filler is suppressed, so that the filler can be accurately transferred to the second liquid channel. It can be filled efficiently. If the filling property is improved, the flatness of the substrate surface is also improved, so that a liquid ejection head with excellent ejection stability can be obtained.

Further, in the method for manufacturing a liquid ejection head of this embodiment, the process is simple and the liquid ejection head can be manufactured at relatively low cost. Furthermore, since the liquid flow path can be formed before forming the ejection ports etc. on the substrate surface, it is less subject to restrictions on the manufacturing method compared to the case where the liquid flow path is formed after the ejection ports etc. are formed. It becomes possible to design a liquid flow path with a relatively high degree of freedom. Therefore, by narrowing the width of the liquid flow path, it is possible to shrink the chip size, which can be expected to reduce costs.

Note that the present invention is not limited to the above embodiments. Various changes and modifications can be made without departing from the spirit and scope of the invention. Examples according to the present disclosure will be shown below based on the above-described embodiments.

(Second embodiment)
The configuration of the liquid ejection head in the second embodiment will be described. In the following description, only the parts that are different from the first embodiment will be mainly described, and the description of the same parts as the first embodiment will be omitted.

FIG. 7 shows the configuration of a liquid ejection head in the second embodiment. In the liquid ejection head according to the second embodiment, convex portions 23 are formed on both left and right sides of the second liquid flow path 14 in the lateral direction of the substrate 10 . Since the convex portions 23 are formed on both the left and right sides of the second liquid flow path, the bubbles 24 can be subdivided to a size that does not block the second liquid flow path 14. Note that even if the convex portion is formed only on one side of the second liquid channel in the transverse direction of the substrate, the effect of dividing the bubbles into smaller pieces can be obtained; Since the convex portions are formed on both the left and right sides, it becomes easier to divide the bubbles into smaller pieces.

From the above, by forming the convex portions on both the left and right sides of the second liquid channel in the transverse direction of the substrate, it is possible to not only suppress the creeping up of the filler but also to prevent air bubbles from forming in the channel. can be subdivided.

(Third embodiment)
The configuration of a liquid ejection head in the third embodiment will be described. FIG. 8(b) is a cross-sectional view of a liquid ejection head in the third embodiment. The liquid ejection head of the third embodiment is a so-called circulation type liquid ejection head, and has a liquid recovery channel in addition to a liquid supply channel as a liquid channel in the transverse direction of the substrate 10. This is different from the first embodiment. The liquid supply channel has a first supply channel and a second supply channel, and the liquid recovery channel has a first recovery channel and a second recovery channel. That is, the first liquid flow path has a first supply flow path and the first recovery flow path, and the second liquid flow path has a second supply flow path and a second recovery flow path. There is.

In the liquid ejection head of this embodiment, the liquid that has flowed through the first supply flow path and the second supply flow path is supplied to the pressure chamber 12 and is ejected from the ejection port 11 . The liquid that has not been discharged is recovered from the pressure chamber 12 into the second recovery channel and the first recovery channel. That is, the liquid circulates in the order of the first supply channel, the second supply channel, the pressure chamber 12, the second recovery channel, and the first recovery channel. By circulating the liquid, it is possible to suppress increase in viscosity due to evaporation of the liquid and thereby suppress ejection failure.

The liquid supply channel and the liquid recovery channel can be manufactured by the same method as in the first embodiment. Note that the structures of the liquid supply channel and the liquid recovery channel may be different, but from the viewpoint of manufacturing, it is preferable that they have a common structure. Further, the positions where the convex portions of the liquid supply channel and the liquid recovery channel are formed may be reversed with respect to the position of the ejection port.

From the above, even if the liquid channel has a liquid supply channel and a liquid recovery channel, by having a convex part in the liquid channel, filler can be Climbing can be suppressed.

Note that the present invention is not limited to the above embodiments. Various changes and modifications can be made without departing from the spirit and scope of the invention. Further, a form in which the respective embodiments are appropriately combined is also possible.

(Comparative example)
Next, a liquid ejection head of a comparative example will be described. FIG. 12 is a schematic diagram showing a process of filling a filler into a liquid ejection head in a comparative example. The liquid ejection head 70 of the comparative example has a tapered liquid flow path, that is, a liquid flow path 71 including a first liquid flow path 72 having a wide flow path width and a second liquid flow path 73 having a narrow flow path width. . Note that the liquid ejection head 70 of the comparative example does not have the protrusion 23 in the liquid flow path.

When manufacturing such a liquid ejection head, concerns arise about the fillability of the filler. FIG. 12A shows a schematic diagram of filling the second liquid flow path 73 with the filler 15 using, for example, the dispense needle 26. If an attempt is made to directly fill the second liquid flow path 73 with the filler 15 using the dispense needle 26, air bubbles will be trapped, which will affect the flatness of the substrate, as well as the accuracy of the ejection port and the ejection stability. Therefore, instead of applying the filler 15 directly to the second liquid flow path 73, the filler 15 is spread through the connecting surface 74 where the first liquid flow path 72 and the second liquid flow path 73 connect. The liquid channel 73 is filled with a filler.

Further, the connection surface 74 has considerable variation in height due to tolerances during the manufacturing of the flow path. That is, when filling with the filler, the distance between the dispensing needle 26 and the connecting surface 74 also varies. If it is attempted to fill the filler with a distance between the dispensing needle 26 and the connection surface 74, the filler 15 may spread as shown in FIG. 12(b). Furthermore, as the filler 15 spreads, it comes close to the side wall of the first liquid flow path, and the filler 15 creeps up the side wall, which may result in the second liquid flow path 73 not being sufficiently filled. Furthermore, if the distance between the dispensing needle 26 and the connecting surface 74 is large, as shown in FIG. There is a risk of embracing 75. If the second liquid flow path 73 is filled with the filler 15 while enclosing air bubbles 75, the flatness of the substrate surface may be affected, and the accuracy of forming the ejection port and the ejection stability may also be affected. .

On the other hand, when trying to fill the filler in a state where the distance between the dispensing needle 26 and the connecting surface 74 is close as shown in FIG. There is a risk that it will rise. Even in this case, there is a possibility that the second liquid flow path 73 will not be sufficiently filled.

Next, a schematic diagram is shown in which the liquid flow path of a liquid ejection head of a comparative example is blocked by air bubbles 24.

In a liquid ejection head, bubbles may be generated within the flow path, or bubbles may be included in the supplied liquid. In such a case, there is a possibility that minute bubbles gather to form large bubbles. As described above, the liquid ejection head of the comparative example does not have the protrusion 23 in the liquid flow path. Therefore, as shown in FIG. 13(a), when the generated large bubble 24 is supplied from the liquid flow path to the pressure chamber 12, as shown in FIG. 13(b), the second liquid flow path 14 is may become blocked. If the second liquid flow path 14 is blocked by the bubbles 24, the amount of liquid supplied to the pressure chamber will decrease, and there is a possibility that a discharge failure may occur.

Examples according to the present invention will be shown below based on the above-described embodiments.

Example 1 is shown below. In addition, in the case of the formation process and structure similar to the above-mentioned embodiment, explanation using figures will be omitted.

FIG. 9 is a schematic diagram of a liquid ejection head in Example 1. The state of the liquid ejection head is the completed state, that is, the state shown in FIG. 2(b) in the embodiment. The thickness of the substrate 10 was 725 μm.

FIG. 9A is a top view of the liquid ejection head viewed from the first surface 21 side. As for the structure, one row of second liquid flow paths 14 is formed along the longitudinal direction of the substrate, and one row of ejection ports 11 is formed on each side of the second liquid flow path 14 along the longitudinal direction of the substrate for the liquid ejection head. It is something that exists. In Example 1, the opening shape of the second liquid flow path 14 was square, and the opening size was 100 μm. Further, the interval between the ends of adjacent second liquid channels 14 was set to 50 μm. In the lateral direction, the distance from the opening center of the second liquid flow path 14 to the opening center of the discharge port 11 was 130 μm. Further, the opening shape and opening dimensions of the discharge port 11 were a perfect circle with a diameter of 8 μm. In the longitudinal direction, the interval between adjacent ejection ports 11 was 40 μm. Note that the left and right discharge port arrays with respect to the second liquid flow path 14 do not necessarily have to be arranged symmetrically, and may be arranged in different positional relationships on the left and right sides, taking into account the discharge port size, discharge characteristics, etc. It's okay.

FIG. 9(b) is a sectional view taken along line BB' in FIG. 9(a). The opening size of the first liquid flow path 13 in the transverse direction was 400 μm, and the opening size in the longitudinal direction was 20000 μm. The widthwise dimension of the convex portion 23 was 150 μm, and the height was 100 μm. Further, as shown in the perspective view of the liquid ejection head substrate in FIG. 9(c), the convex portion 23 extends in the longitudinal direction.

Example 2 is shown below. In addition, in the case of the formation process and structure similar to the above-mentioned embodiment, explanation using figures will be omitted. Also, regarding specific dimensions, positional relationships, etc., cases similar to those in Example 1 will be omitted.

FIG. 10 is a schematic diagram of a liquid ejection head in Example 2. The state of the liquid ejection head is the completed state, that is, the state shown in FIG. 2(b).

FIG. 10A is a top view of the liquid ejection head substrate viewed from the first surface 21 side. The configuration is the same as that of the first embodiment. FIG. 10(b) is a cross-sectional view taken along line CC' in 10(a). The opening size in the lateral direction and the opening size in the longitudinal direction of the first liquid flow path 13 are the same as in Example 1. In Example 2, two convex portions 23 are formed on one side of the second liquid flow path in the transverse direction of the substrate. Of the two protrusions, the one closer to the second liquid flow path is smaller. Specifically, the short dimension of the protrusion near the second liquid flow path 14 is 60 μm, the height is 40 μm, and the short dimension of the protrusion near the channel wall of the first liquid flow path 13 is 90 μm. The height was set to 60 μm.

Example 3 is shown below. In addition, in the case of the formation process and structure similar to the above-mentioned embodiment, explanation using figures will be omitted. Furthermore, descriptions of specific dimensions, positional relationships, etc. will be omitted if they are the same as in the above embodiments.

FIG. 8 is a schematic diagram of a liquid ejection head in Example 2. The liquid ejection head is in a completed state, that is, the state shown in FIG. 2(b).

FIG. 8A is a top view of the liquid ejection head viewed from the first surface 21 side. As for the structure, two lines of second liquid channels 14 are formed along the longitudinal direction of the liquid ejection head substrate, one being a liquid supply channel and the other being a liquid recovery channel. Moreover, one row of discharge ports 11 is formed between the second liquid channels 14 along the longitudinal direction. It is preferable that the distance between the opening centers of the second liquid channels 14 arranged on the left and right sides in the lateral direction be appropriately set in consideration of the ejection port size, ejection characteristics, and the like. In Example 3, the distance in the width direction of the left and right second liquid channels 14 was set to 300 μm. The discharge port 11 was arranged at an intermediate position dividing the left and right second liquid flow paths 14 into two equal parts. Note that the shapes and dimensions of the left and right second liquid channels 14 may be different between the left and right rows. The ejection port 11 formed between the left and right second liquid flow paths 14 does not necessarily need to be placed at an intermediate position that divides the left and right second liquid flow paths 14 into two, and the ejection characteristics etc. It can be adjusted as appropriate.

FIG. 8(b) is a sectional view taken along line DD' in FIG. 8(a). Since the second liquid flow paths 14 are formed in two rows on the left and right in the longitudinal direction, the first liquid flow paths 13 are formed corresponding to the left and right sides, respectively. The dimensions of each first liquid flow path 13 were the same as in Example 1. Further, the dimensions of the convex portion 23 were also made the same as in Example 1. Assuming that the distance between the left and right first liquid channels in the transverse direction is L, the distance L between the left and right first liquid channels is determined by taking into account the distance between the left and right second liquid channels 14 and the Si strength. It is preferable to set it appropriately. In Example 3, the distance L between the left and right first liquid channels was 200 μm.

Example 4 is shown below. In addition, in the case of the formation process and structure similar to the above-mentioned embodiment, explanation using figures will be omitted. Furthermore, descriptions of specific dimensions, positional relationships, etc. will be omitted if they are similar to those of the above-described embodiments.

FIG. 11 is a schematic diagram of a liquid ejection head in Example 4. The state of the liquid ejection head is the completed state, that is, the state shown in FIG. 2(b).

FIG. 11A is a bottom view of the liquid ejection head substrate viewed from the first surface 21 side. The configuration is the same as that of the first embodiment.

FIG. 11(b) is a sectional view taken along line EE' in FIG. 11(a). The opening size in the lateral direction and the opening size in the longitudinal direction of the first liquid flow path 13 are the same as in Example 1. As shown in the perspective view of the liquid ejection head in FIG. 11(c), the convex portion 23 is formed only on the connection surface 61 corresponding to the portion where the second liquid flow path 14 is formed. In addition, the widthwise dimension and height dimension of the convex portion 23 were the same as in Example 1.

To summarize the above, this disclosure includes the following configuration.

(Configuration 1)
A discharge port for discharging liquid, a first surface on the side where the discharge port is formed, a second surface that is the back surface of the first surface, and a combination of the first surface and the second surface. A liquid ejection head comprising: a substrate having a liquid flow path that communicates with the liquid flow path; the liquid flow path is connected to a first liquid flow path connected to the second surface; a second liquid flow path that communicates with the first liquid flow path; and a connection surface that connects the first liquid flow path and the second liquid flow path; The opening length of the second liquid flow path in the direction is shorter than the opening length of the first liquid flow path, and the connection surface has a convex portion that projects in the direction of the second surface. , the convex portion has a tapered apex, a first slope inclined from the apex toward the second liquid flow path, and a first slope of the first liquid flow path adjacent to the convex portion. A liquid ejection head characterized in that it includes a second slope that slopes toward a side wall.

(Configuration 2)
The liquid ejection head according to configuration 1, wherein the first slope has an inclination angle of 20° to 70° with respect to the connecting surface.

(Configuration 3)
The liquid ejection head according to configuration 1 or 2, wherein the second slope has an inclination angle of 20° to 70° with respect to the connecting surface.

(Configuration 4)
4. The liquid ejection head according to any one of configurations 1 to 3, wherein the angle of inclination of the first slope with respect to the connection surface is greater than the angle of inclination of the second slope with respect to the connection surface.

(Configuration 5)
5. The liquid ejection head according to any one of configurations 1 to 4, wherein a hydrophilic film is formed on an inner wall of the second liquid flow path.

(Configuration 6)
The liquid ejection head according to configuration 5, wherein the hydrophilic film has a contact angle with respect to pure water of 40° or less.

(Configuration 7)
5. The liquid ejection head according to any one of configurations 1 to 4, wherein a lipophilic film is formed on an inner wall of the second liquid flow path.

(Configuration 8)
8. The liquid ejection head according to configuration 7, wherein the lipophilic film has a contact angle with respect to pure water of 150° or more.

(Configuration 9)
If the opening length of the first liquid flow path in the transverse direction of the substrate is a, and the length of the convex portion is w, a configuration 1 has a relationship of a/4<w<a/2. 9. The liquid ejection head according to any one of 8.

(Configuration 10)
If the depth of the first liquid flow path is b, and the height from the connection surface to the top is h, then any one of configurations 1 to 9 has a relationship of b/20<h<b. 1. The liquid ejection head according to item 1.

(Configuration 11)
11. The liquid ejection head according to any one of configurations 1 to 10, wherein a plurality of the convex portions are formed on one side of the second liquid flow path in the lateral direction of the substrate.

(Configuration 12)
12. The liquid ejection head according to any one of Structures 1 to 11, wherein the convex portion is formed on both left and right sides of the second liquid flow path in the lateral direction of the substrate.

(Configuration 13)
13. The liquid ejection head according to any one of configurations 1 to 12, wherein the liquid flow path is a flow path that supplies liquid to the ejection port.

(Configuration 14)
13. The liquid ejection head according to any one of configurations 1 to 12, wherein the liquid flow path is a flow path for recovering liquid that has not been ejected from the ejection port.

(Configuration 15)
A discharge port for discharging liquid, a first surface on the side where the discharge port is formed, a second surface that is the back surface of the first surface, and a combination of the first surface and the second surface. A method of manufacturing a liquid ejection head comprising: a substrate having a liquid flow path communicating with the first liquid flow path, the liquid flow path being connected to the second surface; a second liquid flow path that connects to the first surface and communicates with the first liquid flow path, and a connection surface that connects the first liquid flow path and the second liquid flow path; The opening length of the second liquid flow path in the lateral direction of the substrate is shorter than the opening length of the first liquid flow path, and a protrusion protrudes in the direction of the second surface on the connection surface. the convex portion has a tapered apex, a first slope sloped from the apex toward the second liquid flow path, and a first liquid adjacent to the convex portion; a step of preparing the substrate including a second slope inclined toward a side wall of the channel, a step of pasting tape to an opening of the second liquid channel, and a step of filling the second liquid channel. the step of filling the filler with a filler, the step of removing the tape, and the step of removing the filler, and in the step of filling the filler, dropping the filler on the top of the A method of manufacturing a liquid ejection head, characterized in that the filler flows on a first slope and a second slope.

(Configuration 16)
16. The method for manufacturing a liquid ejection head according to configuration 15, wherein the filler is hydrophilic, and the method includes a step of forming a hydrophilic film on an inner wall of the second liquid flow path before the step of filling the filler with the filler.

(Configuration 17)
If the opening length of the first liquid flow path in the lateral direction of the substrate is a, and the length of the convex portion is w, then a configuration 15 has a relationship of a/4<w<a/2. or 16. The method for manufacturing a liquid ejection head according to 16.

(Configuration 18)
Any one of Configurations 15 to 17, where b is the depth of the first liquid flow path and h is the height from the connection surface to the top, and the relationship b/20<h<b holds. A method for manufacturing a liquid ejection head according to .

(Configuration 19)
19. The method for manufacturing a liquid ejection head according to any one of configurations 15 to 18, wherein the liquid flow path is a flow path that supplies liquid to the ejection port.

(Configuration 20)
19. The method for manufacturing a liquid ejection head according to any one of configurations 15 to 18, wherein the liquid flow path is a flow path for collecting liquid that has not been ejected from the ejection port.

9 Discharge port forming member 10 Substrate 11 Discharge port 13 First liquid channel 14 Second liquid channel 15 Filler 21 First surface 21
22 Second surface 22
23 Convex portion 26 Dispense needle 44 Recording element substrate (liquid ejection head)
53 Liquid flow path 61 Connection surface 63 First slope 64 Second slope 65 Top part

Claims (20)

a discharge port for discharging liquid;
A first surface on the side where the discharge port is formed, a second surface that is the back surface of the first surface, and a liquid flow path that communicates the first surface and the second surface. a substrate having;
A liquid ejection head comprising:
The liquid flow path includes a first liquid flow path connected to the second surface, and a second liquid flow path connected to the first surface and communicating with the first liquid flow path. , having a connection surface where the first liquid flow path and the second liquid flow path connect,
The opening length of the second liquid flow path in the lateral direction of the substrate is shorter than the opening length of the first liquid flow path,
The connecting surface has a convex portion protruding in the direction of the second surface,
The convex portion has a tapered apex, a first slope sloped from the apex toward the second liquid flow path, and a side wall of the first liquid flow path adjacent to the convex portion. A liquid ejection head characterized in that it includes a second slope inclined toward the direction of the liquid ejection head. The liquid ejection head according to claim 1, wherein the first slope has an inclination angle of 20° to 70° with respect to the connecting surface. The liquid ejection head according to claim 1, wherein an inclination angle of the second slope with respect to the connection surface is 20° to 70°. The liquid ejection head according to claim 1, wherein the angle of inclination of the first slope with respect to the connection surface is greater than the angle of inclination of the second slope with respect to the connection surface. The liquid ejection head according to claim 1, wherein a hydrophilic film is formed on an inner wall of the second liquid flow path. The liquid ejection head according to claim 5, wherein the contact angle of the hydrophilic film with respect to pure water is 40° or less. The liquid ejection head according to claim 1, wherein a lipophilic film is formed on an inner wall of the second liquid flow path. The liquid ejection head according to claim 7, wherein the lipophilic film has a contact angle with respect to pure water of 150° or more. A claim in which, where a is the opening length of the first liquid flow path in the lateral direction of the substrate, and w is the length of the convex portion, the relationship is a/4<w<a/2. 1. The liquid ejection head according to 1. The liquid ejection head according to claim 1, wherein b/20<h<b, where b is the depth of the first liquid flow path and h is the height from the connection surface to the top. . The liquid ejection head according to claim 1, wherein a plurality of the convex portions are formed on one side of the second liquid flow path in the lateral direction of the substrate. The liquid ejection head according to claim 1, wherein the convex portion is formed on both left and right sides of the second liquid flow path in the lateral direction of the substrate. The liquid ejection head according to any one of claims 1 to 12, wherein the liquid flow path is a flow path that supplies liquid to the ejection port. 13. The liquid ejection head according to claim 1, wherein the liquid flow path is a flow path for recovering liquid that has not been ejected from the ejection port. a discharge port for discharging liquid;
A first surface on the side where the discharge port is formed, a second surface that is the back surface of the first surface, and a liquid flow path that communicates the first surface and the second surface. a substrate having;
A method of manufacturing a liquid ejection head comprising:
The liquid flow path includes a first liquid flow path connected to the second surface, and a second liquid flow path connected to the first surface and communicating with the first liquid flow path. , has a connection surface where the first liquid flow path and the second liquid flow path are connected, and the opening length of the second liquid flow path in the lateral direction of the substrate is equal to the first liquid flow path. The connecting surface has a convex portion that is shorter than the opening length of the liquid flow path and protrudes in the direction of the second surface, and the convex portion has a tapered apex, and the convex portion extends from the apex to the second surface. preparing the substrate, the substrate including a first slope that slopes toward the second liquid flow path, and a second slope that slopes toward the side wall of the first liquid flow path that is adjacent to the convex portion;
affixing a tape to the opening of the second liquid flow path;
filling the second liquid flow path with a filler;
removing the tape;
removing the filler;
has
A method for manufacturing a liquid ejection head, characterized in that in the step of filling the filler, the filler flows on the first slope and the second slope by dropping the filler on the top. the filler is hydrophilic;
16. The method for manufacturing a liquid ejection head according to claim 15, further comprising a step of forming a hydrophilic film on an inner wall of the second liquid flow path before the step of filling the filler. A claim in which, where a is the opening length of the first liquid flow path in the lateral direction of the substrate, and w is the length of the convex portion, the relationship is a/4<w<a/2. 16. The method for manufacturing a liquid ejection head according to 15. The liquid ejection head according to claim 15, wherein b/20<h<b, where b is the depth of the first liquid flow path and h is the height from the connection surface to the top. manufacturing method. The method for manufacturing a liquid ejection head according to any one of claims 15 to 18, wherein the liquid flow path is a flow path that supplies liquid to the ejection port. The method for manufacturing a liquid ejection head according to any one of claims 15 to 18, wherein the liquid flow path is a flow path for recovering liquid that has not been ejected from the ejection port.

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