JP2024063458A - Liquid ejection head and manufacturing method thereof - Google Patents

Abstract

[Problem] To ensure electrical reliability of a liquid ejection head. [Solution] A liquid ejection head 10 has a recording element substrate 1 having a plurality of electrode terminals 11 arranged in a predetermined arrangement direction, a plurality of connection terminals 12 provided at positions facing the plurality of electrode terminals 11, a plurality of wires 13 electrically connecting the plurality of electrode terminals 11 and the plurality of connection terminals 12, and sealing portions 5, 6 sealing the electrical connection portions 11-13 including the plurality of electrode terminals 11, the plurality of connection terminals 12, and the plurality of wires 13, and a connection position 17 for at least one wire 13b located at an end of the arrangement direction of the plurality of wires 13 to a connection terminal 12b is closer to the recording element substrate 1 than a connection position 16 for the connection terminal 12a of the other wires 13a. [Selected Figure] Figure 2

Description

The present invention relates to a liquid ejection head and a manufacturing method thereof.

Electrical connections made by wire bonding in liquid ejection heads are generally sealed with a sealant to protect them from liquids and external forces. To improve the reliability of such seals, two types of sealants with different viscosities are used. In this method, low-viscosity sealant is filled into small gaps between wires, and then high-viscosity sealant is applied on top of it, and the sealant is then hardened by thermal curing. However, because low-viscosity sealant has high fluidity, it flows out into unnecessary areas, resulting in a thin overall sealing part and the risk of damage to the electrical connections due to corrosion caused by liquid penetration. Patent Document 1 describes a technology in which a flow stopper is formed using auxiliary wires to surround the sealed area to be sealed with sealant in order to prevent the sealant from flowing out.

JP 2009-128971 A

However, the technology described in Patent Document 1 suppresses planar outflow of the sealing material by performing auxiliary wire bonding to surround the sealed area, so the range of application is limited to cases where such wire bonding can be performed.
SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a liquid ejection head that ensures electrical reliability and a method for manufacturing the same.

In order to achieve the above-mentioned object, the liquid ejection head of the present invention has a recording element substrate having a plurality of electrode terminals arranged in a predetermined arrangement direction, a plurality of connection terminals provided at positions opposite the plurality of electrode terminals, a plurality of wires electrically connecting the plurality of electrode terminals and the plurality of connection terminals, and a sealing portion that seals the electrical connection portion including the plurality of electrode terminals, the plurality of connection terminals, and the plurality of wires, and the connection position of at least one wire located at the end of the arrangement direction of the plurality of wires to the connection terminal is closer to the recording element substrate than the connection positions of the other wires to the connection terminals.
In addition, the manufacturing method of a liquid ejection head of the present invention is a manufacturing method of a liquid ejection head having a recording element substrate having a plurality of electrode terminals arranged in a predetermined arrangement direction, and a plurality of connection terminals provided at positions opposite the plurality of electrode terminals, and includes a step of electrically connecting the plurality of electrode terminals and the plurality of connection terminals with a plurality of wires by wire bonding to form an electrical connection portion including the plurality of electrode terminals, the plurality of connection terminals, and the plurality of wires, and a step of forming a sealing portion that seals the electrical connection portion, wherein the step of forming the electrical connection portion includes connecting at least one wire located at an end of the plurality of wires in the arrangement direction to the connection terminal at a position closer to the recording element substrate than the other wires.

The present invention ensures electrical reliability of the liquid ejection head.

1A and 1B are a perspective view and a plan view of a liquid ejection head according to an embodiment; 1A and 1B are a plan view and a cross-sectional view of a liquid ejection head according to an embodiment. 5A to 5C are plan views illustrating steps of a method for manufacturing a liquid ejection head according to an embodiment of the present invention. FIG. 11 is a plan view showing a state in which a first sealing material flows in a comparative example. 4 is a plan view showing a state in which a first sealing material flows in the embodiment. FIG. FIG. 13 is a plan view showing a modified example of the second wire according to the embodiment.

The following describes an embodiment of the present invention with reference to the drawings.

Figures 1(a) and 1(b) are respectively a perspective view and a plan view of a liquid ejection head according to an embodiment of the present invention, and Figure 1(c) is a cross-sectional view taken along line AA in Figure 1(b).
The liquid ejection head 10 includes a recording element substrate 1, an electric wiring substrate 2, a support member 3, a protective member 4, a first sealing material 5, and a second sealing material 6. The recording element substrate 1 and the electric wiring substrate 2 are joined to the support member 3 by adhesives 8a and 8b (see FIG. 3(b) and FIG. 3(d)). The recording element substrate 1 and the electric wiring substrate 2 are electrically connected to each other by electric connection parts 11 to 13 including electrode terminals 11, connection terminals 12, and wires 13 described later in order to supply electric signals and power for ejecting liquid from the electric wiring substrate 2 to the recording element substrate 1. The electric connection parts 11 to 13 are sealed by sealing parts 5 and 6 consisting of a first sealing material 5 and a second sealing material 6 in order to protect them from liquid and external forces. The protective member 4 is joined to the electric wiring substrate 2 and the support member 3 by an adhesive 8c (see FIG. 3(g)), and has a rectangular opening 4a that exposes the rectangular recording element substrate 1. As a result, a groove-shaped gap S is formed between the recording element substrate 1 and the protective member 4, and the first sealing material 5 is filled into this gap S, as will be described in detail later.

Fig. 2(a) is a plan view of the liquid ejection head of this embodiment, with the first and second sealing materials omitted from Fig. 1(b). Fig. 2(b) is an enlarged plan view of the area surrounded by the dotted line in Fig. 2(a), and Fig. 2(c) and Fig. 2(d) are cross-sectional views taken along lines B-B and C-C in Fig. 2(b), respectively.
The recording element substrate 1 has a plurality of ejection ports (not shown) for ejecting liquid such as ink, and a plurality of energy generating elements (not shown) for generating energy used to eject the liquid. The recording element substrate 1 also has a plurality of electrode terminals 11 arranged adjacent to the long side surface (first side surface) 1a and arranged in the longitudinal direction (predetermined arrangement direction). The plurality of electrode terminals 11 include a plurality of first electrode terminals 11a that supply electric signals to the energy generating elements, and a plurality of second electrode terminals 11b. The second electrode terminals 11b are dummy terminals that are provided at both ends of the arrangement direction of the plurality of electrode terminals 11 and do not contribute to the supply of electric signals to the energy generating elements. In response to this, the electrical wiring substrate 2 has a plurality of connection terminals 12 provided at positions facing the plurality of electrode terminals 11. The plurality of connection terminals 12 include a plurality of first connection terminals 12a that supply electric signals to the recording element substrate 1, and a plurality of second connection terminals 12b. The second connection terminals 12 b are provided at both ends of the multiple connection terminals 12 in the arrangement direction, and are dummy terminals that do not contribute to the supply of electrical signals to the recording element substrate 1 .

The electrode terminals 11 and the connection terminals 12 are electrically connected by wire bonding using wires. That is, the liquid ejection head 10 has a plurality of wires 13 that electrically connect the electrode terminals 11 and the connection terminals 12. The wires 13 constitute a first wire row 14 and a second wire row 15 arranged on both sides of the first wire row 14. The first wire row 14 is made up of a plurality of first wires 13a that connect the first electrode terminal 11a and the first connection terminal 12a, and the second wire row 15 is made up of a plurality of second wires 13b that connect the second electrode terminal 11b and the second connection terminal 12b. Therefore, the second wires 13b are dummy wires that do not contribute to the supply of electrical signals from the electrical wiring board 2 to the recording element board 1. The bonding position (connection position) 17 for the second connection terminal 12b of the second wire row 15 is closer to the recording element substrate 1 than the bonding position (connection position) 16 for the first connection terminal 12a of the first wire row 14. This makes it possible to suppress unnecessary outflow of the low-viscosity first sealing material 5 injected into the gap S between the recording element substrate 1 and the protective member 4, as described below.

Next, the manufacturing method of the liquid ejection head of this embodiment will be described with reference to FIG. 3. FIG. 3(a) to FIG. 3(i) are plan views of the liquid ejection head in each step of the manufacturing method of this embodiment.

3A, a support member 3 is prepared in which a flow path 7 is formed for supplying liquid to the recording element substrate 1. The shape and size of the support member 3 are not particularly limited as long as they are capable of joining the recording element substrate 1 and the electric wiring substrate 2, and the material thereof can be selected from a wide range of materials such as ceramics, resins, and metals. In this embodiment, a thermosetting adhesive 8a, which will be described later, is used as the material for the support member 3, and therefore alumina, which has excellent heat resistance and a small linear expansion coefficient, is used.
Next, as shown in Fig. 3(b), a thermosetting adhesive 8a made of epoxy resin is applied along the periphery of the opening of the flow path 7 of the support member 3. Then, the position of the supply path (not shown) formed in the recording element substrate 1 is aligned with the position of the flow path 7 of the support member 3, and the recording element substrate 1 is bonded to the support member 2 while being heated. In this way, the recording element substrate 1 is joined to the support member 3, as shown in Fig. 3(c).
Next, as shown in FIG. 3( d ), a thermosetting adhesive 8 b made of epoxy resin is applied to the position of the support member 3 where the electric wiring board 2 is to be joined, and then the electric wiring board 2 is joined to the support member 3 by heat and pressure bonding, as shown in FIG. 3( e ).

Next, wire bonding is performed using a capillary (not shown) to electrically connect the electrode terminals 11 and the connection terminals 12 with the wires 13, as shown in Fig. 3(f). Specifically, the wires 13 are bonded such that the wire rows 15 located at both ends in the arrangement direction of the wires 13 are connected to the connection terminals 12 at positions closer to the recording element substrate 1 than the wire row 14 located in the center. In this way, the electrical connections 11 to 13 between the recording element substrate 1 and the electrical wiring substrate 2, including the electrode terminals 11, the connection terminals 12, and the wires 13, are formed.
Next, as shown in FIG. 3(g), a thermosetting adhesive 8c made of epoxy resin is applied in a frame shape to the support member 3 and the electric wiring board 2, and the protective member 4 is bonded to the support member 3 and the electric wiring board 2 by heat and pressure bonding, as shown in FIG. 3(h). At this time, the protective member 4 is bonded to the electric wiring board 2 at a position where the recording element board 1 and the multiple connection terminals 12 of the electric wiring board 2 are exposed from the opening 4a. The shape of the protective member 4 does not have to be a frame shape as in this embodiment, as long as it covers a part of the electric wiring board 2 to protect the electric wiring board 2, thereby forming a groove-like gap between the recording element board 1 and the protective member 4, exposing the multiple connection terminals 12. There is no particular restriction on the material of the protective member 3, but in this embodiment, alumina, which has excellent heat resistance and a small linear expansion coefficient, is used, similar to the support member 3.

Next, a first sealant 5 made of a low-viscosity thermosetting resin is injected into the gap S between the recording element substrate 1 and the electric wiring substrate 2 by a dispense method. Specifically, a dispense needle (not shown) is scanned in the arrangement direction of the plurality of wires 13, and the first sealant 5 is injected into the gap S between the recording element substrate 1 and the electric wiring substrate 2 so as to cover only the first wire row 14. Then, as will be described in detail later, the first sealant 5 flows outward toward the second wire row 15, so that the first sealant 5 fills the gap S as shown in FIG. 3(i).
Then, also by the dispensing method, a second sealing material 6 made of a high-viscosity thermosetting resin is applied from above the first sealing material 5 to the portions of the electrical connection parts 11 to 13 that are not sealed with the first sealing material 5. After application of the second sealing material 6 is completed, the first sealing material 5 and the second sealing material 6 are cured in a curing oven, thereby completing the liquid ejection head 10 shown in FIG.

Here, the effect of the second wire row 15 of this embodiment will be described with reference to Fig. 4 and Fig. 5. Fig. 4(a) to Fig. 4(d) are enlarged plan views showing a schematic view of the low-viscosity first sealant flowing in the gap in a liquid ejection head of a comparative example having no second wire row, and correspond to Fig. 2(b). Fig. 5(a) to Fig. 5(d) are enlarged plan views showing a schematic view of the low-viscosity first sealant flowing in the gap in a liquid ejection head of this embodiment having the second wire row, and correspond to Fig. 2(b).
In the comparative example configuration not having the second wire array 15, the first sealant 5 (see FIG. 4A) injected into the gap S between the recording element substrate 1 and the protective member 4 starts to flow outward in the arrangement direction of the first wire array 14, as shown in FIG. 4B. On the recording element substrate 1 side, such flow stops when it reaches the intersection 1c between the long side 1a and the short side (second side) 1b of the recording element substrate 1, as shown in FIG. 4C, but on the protective member 4 side, it does not stop and continues further outward. Then, when the first sealant 5 reaches the corner 4b of the opening 4a of the protective member 4, a meniscus is formed between the intersection 1c of the recording element substrate 1 and the corner 4b of the protective member 4, as shown in FIG. 4D, and the flow of the first sealant 5 stops completely. Therefore, in the configuration of the comparative example, the flow of the first sealing material 5 does not stop until it reaches the corner 4b of the opening 4a of the protective member 4, and the first sealing material 5 spreads to areas that do not actually need to be filled.

On the other hand, in the configuration of this embodiment having the second wire row 15, the first sealant 5 is injected into the gap S between the recording element substrate 1 and the electric wiring substrate 2 so as to cover only the first wire row 14 as described above (see FIG. 5(a)). The first sealant 5 thus injected starts to flow outward toward the second wire row 15 as shown in FIG. 5(b). Then, when it reaches the second wire row 15, it is drawn toward the recording element substrate 1 along the region between the bonding position 17 of the second wire row 15 and the recording element substrate 1 as shown in FIG. 5(c), and thus the flow of the first sealant 5 on the protective member 4 side stops. Furthermore, when the first sealant 5 reaches the outermost second wire 15a of the second wire row 15, the flow of the first sealant 5 along the bonding position 17 of the second wire row 15 also stops. Finally, when the first sealing material 5 reaches the intersection 1c of the recording element substrate 1, as shown in Fig. 5(d), a meniscus is formed between the intersection 1c and the end 17a of the outermost second wire 15a on the protective member 4 side. This causes the flow of the first sealing material 5 to completely stop.
Therefore, in the configuration of this embodiment, when the recording element substrate 1 is viewed in plan, the first sealant 5 is filled between the recording element substrate 1 and the bonding position 17 of the second wire row 15, and is not filled further toward the protective member 4. In addition, the first sealant 5 is filled inside the line connecting the intersection 1c of the recording element substrate 1 and the bonding position 17a (see FIG. 5D) that is the closest to the intersection 1c among the bonding positions 17 of the second wire row 15, and is not filled outside of that. As a result, the range in which the first sealant 5 is filled in the gap S can be narrowed compared to the configuration of the comparative example described above.

Thus, according to this embodiment, the second wire array 15 is provided on the outside of the arrangement direction of the first wire array 14, and is connected to the electric wiring board 2 at a position closer to the recording element board 1 than the first wire array 14. Such a second wire array 15 can intentionally stop the flow of the first sealant 5 injected into the gap S so as to cover the first wire array 14, and can suppress the first sealant 5 from flowing out to an unnecessary area. As a result, the thickness of the entire sealing part consisting of the first sealant 5 and the second sealant 6 applied thereon can be sufficiently secured, and the protection performance of the electrical connection parts 11 to 13 can be improved, thereby improving the electrical reliability of the liquid ejection head 10.
The number of second wires 13b constituting the second wire row 15 is not limited to five as shown in the figure, and may be four or less, or six or more. In the illustrated embodiment, as shown in FIG. 2B, the interval D between the first wire row 14 and the second wire row 15 is wider than the pitch P between adjacent wires in each of the wire rows 14 and 15, but may be the same. However, in the case where they are the same, the first sealant 5 flowing toward the second wire row 15 is drawn toward the recording element substrate 1 (see FIG. 5D), so that the thickness of the first sealant 5 covering the first wire row 14 may become thinner in the portion adjacent to the second wire row 15. Therefore, the interval D between the first wire row 14 and the second wire row 15 is preferably wider than the pitch P as shown in the figure. In other words, the second wire row 15 is preferably arranged at an interval D wider than the pitch P with respect to the outermost wire 13a (closest to the second wire row 15) of the first wire row 14.

6(a) and 6(b) are plan views showing modified examples of the second wire of the present embodiment, and correspond to FIG. 2(b).
The bonding position 17 of the second wire array 15 for the second connection terminal 12b may be different from the bonding position 16 of the first wire array 14 for the first connection terminal 12a, as long as it is closer to the recording element substrate 1 than the bonding position 16. Specifically, the bonding position 17 of the second wire array 15 may be closer to the recording element substrate 1 in stages as it approaches the intersection 1c of the recording element substrate 1, as shown in FIG. 6(a), or may be closer to the recording element substrate 1 continuously, as shown in FIG. 6(b). This makes it possible to more reliably suppress the first sealant 5 injected into the gap S between the recording element substrate 1 and the protective member 4 from flowing toward the corner 4b of the opening 4a of the protective member 4. On the other hand, as shown in FIG. 6(c), a plurality of second wires 13b may be arranged in a mesh shape by crossing each other, which further promotes the formation of a meniscus and more reliably stops the flow of the first sealant 5.

The disclosure of this embodiment includes the following configurations and methods.
(Configuration 1)
a recording element substrate having a plurality of electrode terminals arranged in a predetermined arrangement direction;
a plurality of connection terminals provided at positions opposite to the plurality of electrode terminals;
a plurality of wires electrically connecting the plurality of electrode terminals and the plurality of connection terminals;
a sealing portion that seals an electrical connection portion including the plurality of electrode terminals, the plurality of connection terminals, and the plurality of wires,
A liquid ejection head, wherein a connection position of at least one of the plurality of wires located at an end in the arrangement direction to the connection terminal is closer to the recording element substrate than connection positions of other wires to the connection terminal.
(Configuration 2)
an electric wiring board having the plurality of connection terminals;
a protective member for covering a portion of the electric wiring board;
The liquid ejection head described in configuration 1, wherein a groove-shaped gap exposing the plurality of connection terminals is formed between the recording element substrate and the protective member, and the sealing portion includes a sealant filled in the gap.
(Configuration 3)
3. The liquid ejection head according to configuration 2, wherein, when the recording element substrate is viewed in plan, the sealant is filled between the recording element substrate and the connection position of the at least one wire.
(Configuration 4)
the recording element substrate has a first side surface that defines the gap and a second side surface that intersects with the first side surface,
A liquid ejection head as described in configuration 3, wherein, when the recording element substrate is viewed in a plane, the sealing material is filled inside a line connecting an intersection between the first side surface and the second side surface of the recording element substrate and a connection position among the connection positions of the at least one wire that is closest to the intersection.
(Configuration 5)
5. The liquid ejection head of any one of configurations 1 to 4, wherein the at least one wire includes at least two wires.
(Configuration 6)
The liquid ejection head according to configuration 5, wherein the at least two wires cross each other.
(Configuration 7)
7. The liquid ejection head according to configuration 5 or 6, wherein connection positions of the at least two wires to the connection terminals are closer to the recording element substrate as they approach the intersection.
(Configuration 8)
8. The liquid ejection head according to configuration 7, wherein connection positions of the at least two wires to the connection terminals are gradually closer to the recording element substrate as they approach the intersection.
(Configuration 9)
8. The liquid ejection head according to configuration 7, wherein connection positions of the at least two wires to the connection terminals become successively closer to the recording element substrate as they approach the intersection.
(Configuration 10)
A liquid ejection head described in any one of configurations 1 to 9, wherein the other wires include a plurality of other wires, and the at least one wire is arranged at a distance from a wire among the plurality of other wires that is closest to the at least one wire at a distance greater than the pitch between the plurality of other wires.
(Configuration 11)
11. The liquid ejection head according to any one of configurations 1 to 10, wherein the at least one wire is a dummy wire that does not contribute to supplying an electrical signal to the recording element substrate.
(Configuration 12)
12. The liquid ejection head according to any one of configurations 1 to 11, wherein the at least one wire is provided at both ends in the arrangement direction.
(Configuration 13)
A method for manufacturing a liquid ejection head having a recording element substrate having a plurality of electrode terminals arranged in a predetermined arrangement direction, and a plurality of connection terminals provided at positions facing the plurality of electrode terminals, comprising the steps of:
a step of electrically connecting the plurality of electrode terminals and the plurality of connection terminals with a plurality of wires by wire bonding to form an electrical connection portion including the plurality of electrode terminals, the plurality of connection terminals, and the plurality of wires;
forming a sealing portion that seals the electrical connection portion;
A method for manufacturing a liquid ejection head, wherein the process of forming the electrical connection portion includes connecting at least one wire located at an end of the plurality of wires in the arrangement direction to the connection terminal at a position closer to the recording element substrate than the other wires.
(Configuration 14)
a step of disposing an electric wiring board having the plurality of connection terminals such that the plurality of connection terminals face the plurality of electrode terminals;
and disposing a protective member so as to cover a portion of the electric wiring board, and forming a groove-shaped gap between the recording element board and the protective member, through which the plurality of connection terminals are exposed;
14. The method of claim 13, wherein the step of forming the sealing portion includes injecting a sealant into the gap so as to cover only the other wires of the plurality of wires.

REFERENCE SIGNS LIST 1 recording element substrate 2 electric wiring substrate 4 protective member 5 first sealing material 10 liquid ejection head 11a first wire 11b second wire

Claims (14)

a recording element substrate having a plurality of electrode terminals arranged in a predetermined arrangement direction;
a plurality of connection terminals provided at positions opposite to the plurality of electrode terminals;
a plurality of wires electrically connecting the plurality of electrode terminals and the plurality of connection terminals;
a sealing portion that seals an electrical connection portion including the plurality of electrode terminals, the plurality of connection terminals, and the plurality of wires,
A liquid ejection head, wherein a connection position of at least one of the plurality of wires located at an end in the arrangement direction to the connection terminal is closer to the recording element substrate than connection positions of other wires to the connection terminal. an electric wiring board having the plurality of connection terminals;
a protective member for covering a portion of the electric wiring board;
The liquid ejection head according to claim 1 , wherein a groove-shaped gap exposing the plurality of connection terminals is formed between the recording element substrate and the protective member, and the sealing portion includes a sealant filled in the gap. The liquid ejection head according to claim 2, wherein, when the recording element substrate is viewed in plan, the sealing material is filled between the recording element substrate and the connection position of the at least one wire. the recording element substrate has a first side surface that defines the gap and a second side surface that intersects with the first side surface,
A liquid ejection head as described in claim 3, wherein, when the recording element substrate is viewed in a plane, the sealing material is filled inside a line connecting an intersection between the first side surface and the second side surface of the recording element substrate and a connection position among the connection positions of the at least one wire that is closest to the intersection. The liquid ejection head according to any one of claims 1 to 4, wherein the at least one wire includes at least two wires. The liquid ejection head according to claim 5, wherein the at least two wires cross each other. The liquid ejection head according to claim 5, wherein the connection positions of the at least two wires to the connection terminals become closer to the recording element substrate as they approach the intersection. The liquid ejection head according to claim 7, wherein the connection positions of the at least two wires to the connection terminals gradually become closer to the recording element substrate as they approach the intersection. The liquid ejection head according to claim 7, wherein the connection positions of the at least two wires to the connection terminals become successively closer to the recording element substrate as they approach the intersection. The liquid ejection head according to any one of claims 1 to 4, wherein the other wires include a plurality of other wires, and the at least one wire is disposed at a distance from a wire among the plurality of other wires that is closest to the at least one wire at a distance greater than the pitch between the plurality of other wires. The liquid ejection head according to any one of claims 1 to 4, wherein the at least one wire is a dummy wire that does not contribute to supplying an electrical signal to the recording element substrate. The liquid ejection head according to any one of claims 1 to 4, wherein the at least one wire is provided at both ends in the arrangement direction. A method for manufacturing a liquid ejection head having a recording element substrate having a plurality of electrode terminals arranged in a predetermined arrangement direction, and a plurality of connection terminals provided at positions facing the plurality of electrode terminals, comprising the steps of:
a step of electrically connecting the plurality of electrode terminals and the plurality of connection terminals with a plurality of wires by wire bonding to form an electrical connection portion including the plurality of electrode terminals, the plurality of connection terminals, and the plurality of wires;
forming a sealing portion that seals the electrical connection portion;
A method for manufacturing a liquid ejection head, wherein the process of forming the electrical connection portion includes connecting at least one wire located at an end of the plurality of wires in the arrangement direction to the connection terminal at a position closer to the recording element substrate than the other wires. a step of disposing an electric wiring board having the plurality of connection terminals such that the plurality of connection terminals face the plurality of electrode terminals;
and disposing a protective member so as to cover a portion of the electric wiring board, and forming a groove-shaped gap between the recording element board and the protective member, through which the plurality of connection terminals are exposed;
The method for manufacturing a liquid ejection head according to claim 13 , wherein the step of forming the sealing portion includes injecting a sealant into the gap so as to cover only the other wires of the plurality of wires.

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