Liquid ejection unit and manufacturing method thereof

Abstract

To provide a liquid discharge unit which can suppress adhesion of a sealing material to a position exceeding a desired region, and a method for manufacturing the same.SOLUTION: A liquid discharge unit 1 includes a liquid discharge chip 10 having a discharge port for discharging liquid, a wiring board 20 which is electrically connected to the liquid discharge chip 10 by an electric connection part, and a sealing part 40 which is configured by curing a liquid sealing material and fills the electric connection part, wherein the liquid discharge chip 10 has a first surface 10S where the electric connection part is provided, a second surface 10U crossing the first surface 10S and a third surface 10T on a reverse side of the first surface 10S, and the second surface 10U has at least one step in a region with which the sealing part 40 can be brought into contact.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to a liquid ejection unit and a method for manufacturing the same. [Background technology]

[0002] Devices such as inkjet printers are equipped with liquid ejection units. Inkjet printers can form characters and images by ejecting minute droplets of ink using an inkjet recording head equipped with the liquid ejection unit. The liquid ejection unit includes a liquid ejection substrate having ejection ports for ejecting liquid, and a wiring substrate electrically connected to the liquid ejection substrate by an electrical connection portion. The electrical connection portion is buried within a sealing portion to ensure electrical reliability. The sealing portion is formed by hardening a liquid sealing material.

[0003] The liquid ejection unit configured as above is assembled into an apparatus in a state where it is joined to a support member such as a base substrate. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-138520 Summary of the Invention [Problem to be solved by the invention]

[0005] As described above, the liquid ejection unit is bonded to a support member such as a base substrate. Therefore, if the liquid sealing material flows into the bonding surface of the liquid ejection unit with the support member when forming the sealing portion, the hardened sealing material will become interposed between the liquid ejection unit and the support member. In this case, the accuracy of the positioning of the liquid ejection unit will decrease. Therefore, for example, when the liquid ejection unit is used in an inkjet recording head, the accuracy of the characters and images formed will also be affected.

[0006] To avoid the above-described problems, it may be possible to form a sealing portion after joining the liquid ejection unit and the support member. However, in this case, the electrical connection portion is exposed to the outside during various manufacturing processes, and there is a risk that the electrical connection portion may be adversely affected during these processes. Therefore, this is not necessarily a good solution. Furthermore, some kind of problem may occur if the sealing material adheres to a position beyond the desired area, not just when the sealing material adheres to the joining surface of the liquid ejection unit with the support member.

[0007] The present invention provides a liquid ejection unit that can prevent a sealing material from adhering to a position beyond a desired area, and a method for manufacturing the same. [Means for solving the problem]

[0008] The present invention employs the following means to solve the above problems.

[0009] That is, the liquid discharge unit of the present invention is a liquid ejection substrate having an ejection port for ejecting liquid; a wiring substrate electrically connected to the liquid ejection substrate by an electrical connection portion; a sealing portion in which the electrical connection portion is embedded; A liquid ejection unit comprising: the liquid ejection substrate has a first surface on which the electrical connection portion is provided, a second surface intersecting the first surface, and a third surface on the back side of the first surface; The second surface is a first step surface connected to the third surface, a second step surface connected to the third surface, and a step surface connecting the first step surface and the second step surface. provided on the opposite side to the third surface Third step Face and and Among the steps, the first step surface and the third step surface are Area where the sealing portion can be contacted Included in It is characterized by the following.

[0010] Further, a method for manufacturing a liquid ejection unit of the present invention includes the steps of: a connecting step of electrically connecting a liquid ejection substrate having ejection ports for ejecting liquid to a wiring substrate; a sealing portion forming step of embedding the electrical connection portion obtained in the connecting step with a liquid sealing material and hardening the material to form a sealing portion; and the liquid ejection substrate has a first surface on which the electrical connection portion is provided; ,before a second surface intersecting the first surface and a third surface on the reverse side of the first surface, and the second surface is a first step surface connected to the third surface, a second step surface connected to the third surface, and a step surface connecting the first step surface and the second step surface. provided on the opposite side to the third surface Third step surface and steps including and in the sealing portion forming step, the sealing material is supplied to at least a partial region of the second surface on a side connected to the first surface. [Effects of the Invention]

[0011] As described above, according to the present invention, it is possible to prevent the sealing material from adhering to a position beyond the desired area. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic diagram illustrating a basic configuration of a liquid ejection head. [Figure 2] FIG. 2 is a schematic diagram illustrating a basic configuration of a liquid ejection unit. [Figure 3] 5A to 5C are diagrams illustrating the manufacturing process of the liquid ejection unit. [Figure 4] 5A to 5C are diagrams illustrating the manufacturing process of the liquid ejection unit. [Figure 5] 3A to 3C are manufacturing process diagrams of the liquid ejection unit according to the first embodiment. [Figure 6] 3A to 3C are manufacturing process diagrams of the liquid ejection unit according to the first embodiment. [Figure 7] 3A to 3C are manufacturing process diagrams of the liquid ejection unit according to the first embodiment. [Figure 8] 1 is a schematic diagram of a liquid ejection unit according to a first embodiment. [Figure 9]10A to 10C are manufacturing process diagrams of the liquid ejection unit according to the second embodiment. [Figure 10] 10A to 10C are manufacturing process diagrams of the liquid ejection unit according to the second embodiment. [Figure 11] 10A to 10C are manufacturing process diagrams of the liquid ejection unit according to the second embodiment. [Figure 12] 10A to 10C are manufacturing process diagrams of the liquid ejection unit according to the third embodiment. [Figure 13] 10A to 10C are manufacturing process diagrams of the liquid ejection unit according to the third embodiment. [Figure 14] FIG. 10 is a schematic diagram of a liquid ejection unit according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] The following detailed description of the present invention will be given by way of example with reference to the accompanying drawings, although the dimensions, materials, shapes, relative positions, etc. of the components described in the examples are not intended to limit the scope of the present invention unless otherwise specified.

[0014] <Basic configuration and manufacturing method of liquid ejection unit> Before describing the characteristic configuration and manufacturing method of the liquid ejection unit according to this embodiment, the basic configuration and manufacturing method of the liquid ejection unit will be described with reference to Figs. 1 to 4. In this embodiment, a liquid ejection unit provided in an inkjet recording head (liquid ejection head) attached to an inkjet printer will be described as an example. Fig. 1 is a schematic diagram showing the basic configuration of a liquid ejection head provided with a liquid ejection unit, Fig. 1(a) is an exploded perspective view of the liquid ejection head, and Fig. 1(b) is a schematic cross-sectional view showing the vicinity of an ejection port 11 that ejects liquid. Fig. 1(b) shows only one example of the structure in the vicinity of the ejection port 11, and various structures can be adopted. Fig. 2 shows the basic configuration of a liquid ejection unit 1. 3A is a schematic diagram showing the general configuration of the liquid ejection unit 1, where FIG. 3A is a partial plan view of the liquid ejection unit 1, and FIG. 3B is a partial side view of the liquid ejection unit 1. FIGS. 3A and 3B are diagrams showing the manufacturing process of the liquid ejection unit, and show the vicinity of the electrical connection parts in schematic cross-sectional views.

[0015] The liquid ejection unit 1 includes a liquid ejection chip 10 serving as a liquid ejection substrate having a plurality of ejection ports 11, and a wiring substrate 20 electrically connected to the liquid ejection chip 10. The liquid ejection unit 1 configured in this manner is joined to a support member (base substrate) 30 that supports the liquid ejection chip 10.

[0016] The liquid ejection chip 10 includes a liquid flow path 11a that communicates with the ejection orifice 11 and has a liquid supply port. The liquid ejection chip 10 also includes a plurality of elements (electrothermal conversion elements 11b) that convert electrical signals sent from the wiring substrate 20 into thermal energy to eject heated liquid from the ejection orifice 11. The liquid ejection chip 10 also includes wiring 11c that is electrically connected to each of the electrothermal conversion elements 11b. The wiring 11c is electrically connected to wiring on the wiring substrate 20.

[0017] The wiring board 20 has multiple electrical wiring and includes multiple connection sections 21 that are electrically connected to the device main body (the device main body of the inkjet printer). The wiring board 20 is configured using a flexible printed wiring board or the like. The support member 30 includes multiple flow paths 31 that enable ink stored in an ink tank (not shown) to be supplied to the liquid flow path 11a of the liquid ejection chip 10.

[0018] In the liquid ejection head configured as described above, when an electric signal is sent from the device body to the electrothermal conversion element 11b via the wiring board 20, the electric signal is converted into thermal energy by the electrothermal conversion element 11b, and the ink is heated. This generates bubbles in the ink, and the ink is ejected from the ejection port 11 by the pressure of the bubbles.

[0019] Next, a method for manufacturing the liquid ejection unit 1 will be described. In general, the liquid ejection unit 1 is manufactured by fabricating the liquid ejection chip 10 and the wiring substrate 20, and then electrically connecting the liquid ejection chip 10 and the wiring substrate 20. Thereafter, these electrical connections are embedded with a sealing portion. Below, the steps of providing the electrical connections and the steps of providing the sealing portion will be described.

[0020] The liquid ejection chip 10 is provided with pads 12 for electrical connection, and the wiring substrate 20 is similarly provided with pads 22 for electrical connection. As shown in FIG. 3, the liquid ejection chip 10 and the wiring substrate 20 can be electrically connected by welding these pads 12 and 22 together using ultrasonic vibrations while they are in contact with each other. In this embodiment, the portions where the pads 12 and 22 are welded correspond to the electrical connection portions. Note that the pads 12 and 22 can be made of a metal with low electrical resistance, and it is desirable that the material be one that has high bonding reliability. For example, gold is a suitable material for the pads because it has low resistance and is resistant to corrosion.

[0021] The method of electrically connecting the liquid ejection chip 10 and the wiring substrate 20 is not limited to the method using ultrasonic vibration as described above, and various other techniques can be employed. For example, there are methods such as NCP and NCF, which place electrical connection pads close to each other and apply a curable resin around them to connect the pads, and ACP and ACF, which use anisotropic conductive materials. When these methods are employed, the part where the pads are connected corresponds to the electrical connection part. Another method is to provide electrical leads on the wiring substrate 20 and connect the leads to the electrical connection pads of the liquid ejection chip 10. In this case, the leads and the entire connection part between the leads and the pads correspond to the electrical connection part. Furthermore, the pads 22 on the wiring substrate 20 and the pads on the liquid ejection chip 10 correspond to the electrical connection part. There is also a method (called wire bonding) of connecting pads 12 to each other with a conductive metal wire. In this case, the wire and the entire connection portion between the wire and the pads on both ends correspond to the electrical connection portion. The above various electrical connection methods can be selected appropriately depending on the cost and product form.

[0022] After the electrical connections are formed as described above, they are embedded in a sealing portion 40 to prevent short circuits and deterioration of the electrical connections, thereby insulating and protecting the electrical connections. Specifically, a liquid sealing material is supplied to the area including the electrical connections, and the sealing material hardens to form the sealing portion 40, burying the electrical connections. A curable liquid resin material is preferably used as the sealing material for the sealing portion 40. That is, various materials can be used as the sealing material as long as they are cured from a liquid state by some action. Specific examples of sealing materials include epoxy resin, acrylic resin, silicone resin, urethane resin, epoxy acrylate resin, imide resin, and amide resin. Furthermore, various curing methods include two-part mixing curing in which a curing agent is mixed, thermal curing by heating, UV curing by ultraviolet irradiation, and moisture curing. For example, if a thermosetting epoxy resin is used, the liquid epoxy resin can be supplied and then cured by heating, making it easy to form the sealing portion 40.

[0023] The liquid ejection unit 1 manufactured as described above is joined to a support member (base substrate) 30. Furthermore, the connection portion 21 of the wiring board 20 is electrically connected to the device body (the device body of the inkjet printer). Here, in order to output a high-resolution image, it is necessary to join the liquid ejection unit 1 to the support member 30 at a predetermined position with high precision.

[0024] The surface (hereinafter referred to as the "third surface 10T") behind the surface (hereinafter referred to as the "first surface 10S") on which the electrical connection parts of the liquid ejection chip 10 serving as the liquid ejection substrate are provided is bonded to the support member 30 (see FIG. 2(b)). For this bonding, an adhesive such as epoxy resin, acrylic resin, or urethane resin is generally used, and the adhesive can be selected taking into consideration the adhesive strength to the selected member, the usage environment, etc.

[0025] Here, in the process of providing the sealing portion 40, as described above, the liquid sealing material is supplied to the region including the electrical connection portion. At this time, the liquid sealing material flows along the side surface of the liquid ejection chip 10, but normally stops at the ridge portion R between the third surface 10T and the side surface (see FIG. 4). This is because the surface onto which the liquid sealing material spreads is inhibited from spreading because the planar continuity is interrupted at the ridge portion R. However, if there is dirt attached to the ridge portion R or if there is a chip in part of the ridge portion R, the liquid sealing material may flow out from the part with the dirt or chip and creep onto the third surface 10T.

[0026] The liquid sealing material adhering to the third surface 10T is difficult to remove, and the hardened material remains on the third surface 10T. In this case, when the liquid discharge unit 1 is joined to the support member 30, the hardened sealing material becomes trapped between the liquid discharge chip 10 and the support member 30, which may reduce the positioning accuracy of the liquid discharge unit 1.

[0027] Therefore, in the liquid discharge unit and the manufacturing method thereof according to this embodiment, it is possible to prevent the liquid sealing material from flowing onto the third surface 10T. This will be specifically described below.

[0028] Example 1 5 to 8, a liquid ejection unit according to a first embodiment of the present invention and a manufacturing method thereof will be described. 5 to 7 are diagrams showing the manufacturing process of the liquid discharge unit according to Example 1 of the present invention, and Fig. 8 is a schematic diagram of the liquid discharge unit according to Example 1 of the present invention. In both figures, the vicinity of the electrical connection portion is shown in a schematic cross-sectional view.

[0029] First, a method for manufacturing the liquid ejection chip 10 will be described. A plurality of liquid ejection chips 10 are manufactured from a wafer 10X, which serves as a base material such as a silicon substrate. The ejection ports, liquid flow paths, electrothermal conversion elements, wiring, and the like described with reference to FIG. 1(b) are formed on this wafer 10X (not shown in FIGS. 5 to 8). The method for forming these elements is well-known (for example, by photolithography), and therefore a description thereof will be omitted. Pads 12 are also attached to the wafer 10X (see FIG. 5(a)). The surface of the wafer 10X to which the pads 12 are attached (the surface on which electrical connection portions will later be provided) will be referred to as the "first surface 10XS," and the surface behind it will be referred to as the "third surface 10XT." Furthermore, the surface on which the pads 12 of the liquid ejection chips 10, which are later cut into individual pieces from the wafer 10X, are attached (the surface on which the electrical connection parts are later provided) will be referred to as the "first surface 10S," and the surface behind that will be referred to as the "third surface 10T."

[0030] A groove 13X having a U-shaped cross section is formed by dicing on the first surface 10XS of the wafer 10X on which the discharge ports and the like are formed as described above (see FIG. 5(b)). In a typical manufacturing method, the wafer is cut by dicing to separate into individual liquid discharge chips. In contrast, in this embodiment, the groove 13X is formed by first inserting a dicing blade from the first surface 10XS of the wafer 10X so as not to reach the third surface 10XT. In this embodiment, two grooves 13X are formed parallel to each other between adjacent pads 12 (see FIG. 6(a)).

[0031] Thereafter, the wafer 10X is cut by dicing at a position between the two grooves 13X (division process). This results in individual liquid ejection chips 10. By cutting the wafer 10X between the two grooves 13X that were previously formed in the wafer 10X, a step is formed on the side of the liquid ejection chip 10 (see FIG. 6(b)). Here, the side of the liquid ejection chip 10 is a surface that intersects with the first surface 10S, and will be referred to as the "second surface 10U" hereinafter. In this embodiment, this second surface 10U is a surface that connects to the first surface 10S and the third surface 10T.

[0032] Next, as shown in FIG. 7(a), the pads 22 of the separately prepared wiring substrate 20 and the pads 12 of the liquid ejection chip 10 are fused and bonded by ultrasonic vibration or the like, and electrically connected (connection process). Then, to insulate and protect the electrical connection formed by this bonding, a liquid sealing material 40X is supplied to bury the electrical connection. Various methods can be used to supply the sealing material 40X, but one example is to use an air dispenser 100 to dispense the sealing material 40X filled in a syringe from the needle tip (see FIG. 7(b)). The process of supplying the sealing material 40X is preferably performed with the wiring substrate 20 placed on a table or the like, with the liquid ejection chip 10 positioned vertically above the wiring substrate 20.

[0033] When a thermosetting resin (such as an epoxy resin composition) is used as the sealing material 40X, the sealing material 40X is supplied and then heated to harden the sealing material 40X, thereby providing the sealing portion 40 (sealing portion forming step). In this way, the liquid discharge unit 1 can be obtained (see FIG. 8).

[0034] <Advantages of the liquid ejection unit and its manufacturing method according to this embodiment> According to this embodiment, the second surface 10U, which is a side surface of the liquid ejection chip 10, has a step in an area where the sealing portion 40 can come into contact. This second surface 10U is configured to have a step that protrudes from a surface adjacent to the first surface 10S. As a result, a first ridge portion R1 is provided at the boundary between the step surface and the protruding portion of the second surface 10U, and A second ridgeline R2 is provided at the boundary between the third surface 10T and the third surface 10T.

[0035] Therefore, in the process of supplying the liquid sealing material, the liquid sealing material flows along the second surface 10U but stops at the position of the first ridgeline R1. This is because the presence of the first ridgeline R1 interrupts the planar continuity of the second surface 10U, thereby preventing the sealing material from spreading. Furthermore, even if the sealing material overruns the first ridgeline R1, it stops at the second ridgeline R2, thereby preventing the sealing material from adhering to the third surface 10T. Note that in this example, as shown in FIG. 8 , the liquid sealing material is supplied up to the first ridgeline R1. However, since it is sufficient to embed the electrical connection portion with the sealing material, it is not necessarily required to supply the liquid sealing material up to the first ridgeline R1. In other words, in the sealing portion formation process, it is sufficient to supply the sealing material to at least a portion of the second surface 10U on the side connected to the first surface 10S.

[0036] Therefore, when the liquid ejection unit 1 is joined to the support member 30, it is possible to prevent the hardened sealing material from getting caught between the liquid ejection chip 10 and the support member 30. This makes it possible to prevent a decrease in the positioning accuracy of the liquid ejection unit 1. As a result, it becomes possible for an inkjet printer to output high-resolution images. Furthermore, according to the manufacturing method of this embodiment, the electrical connection parts are not exposed to the outside during the manufacturing process, so the electrical connection parts are not adversely affected during the various processes.

[0037] Example 2 A liquid discharge unit according to Example 2 of the present invention and a manufacturing method thereof will be described with reference to Figures 9 to 11. Figures 9 to 11 are manufacturing process diagrams of the liquid discharge unit according to Example 2 of the present invention, and in each diagram, the vicinity of the electrical connection portion is shown in a schematic cross-sectional view.

[0038] First, a method for manufacturing the liquid ejection chip 10A will be described. A plurality of liquid ejection chips 10A are manufactured from a wafer 10X serving as a base material, such as a silicon substrate. The formation of ejection ports and the attachment of pads 12 to the wafer 10X are as described in Example 1. The surface of the wafer 10X to which the pads 12 are attached (the surface on which electrical connection parts will later be provided) will be referred to as the "first surface 10XS," and the surface behind it will be referred to as the "third surface 10XT." Furthermore, the surface of the liquid ejection chips 10A, which will later be obtained by cutting the wafer 10X and dividing them into individual pieces, to which the pads 12 are attached (the surface on which electrical connection parts will later be provided) will be referred to as the "first surface 10AS," and the surface behind it will be referred to as the "third surface 10AT."

[0039] A single groove 14X is formed by dry etching on the third surface 10XT of the wafer 10X (see FIG. 9(a)) on which the discharge ports and the like are formed as described above (see FIG. 9(b)). Next, two grooves 15X are formed by blade dicing on the first surface 10XS of the wafer 10X, directly behind the groove 14X and along both sides of the groove 14X.

[0040] Thereafter, the wafer 10X is cut by dicing at a position between the two grooves 15X and passing through the center of the groove 14X (division process). This results in individual liquid ejection chips 10A. By cutting the wafer 10X at a position between the two grooves 15X and passing through the center of the groove 14X, two steps are formed on the side of the liquid ejection chip 10A (see FIG. 10(b)). Here, the side of the liquid ejection chip 10A is a surface that intersects with the first surface 10AS and is hereinafter referred to as the "second surface 10AU." In this embodiment, this second surface 10AU is a surface that connects to the first surface 10AS and the third surface 10AT.

[0041] In this example, the grooves 15X are formed on the first surface 10XS using blade dicing, and the grooves 14X are formed on the third surface 14AT using dry etching. However, any groove formation process can be used as long as the desired shape is obtained. The grooves on both surfaces may be formed by blade dicing, or they may be formed by dry etching. Alternatively, the grooves 15X may be formed on the first surface 10XS using dry etching, and the grooves 14X may be formed on the third surface 14AT using blade dicing. Furthermore, other methods such as wet etching or sandblasting may be used to form the grooves. Any appropriate method can be adopted based on the overall manufacturing process of the liquid ejection head.

[0042] Next, the pads 22 of the separately prepared wiring substrate 20 and the pads 12 of the liquid ejection chip 10A are electrically connected as shown in FIG. 11(a) (connection step). For example, the pads 12 of the liquid ejection chip 10A and the pads 22 of the wiring substrate 20 can be electrically connected using ACF. ACF is an abbreviation for anisotropic conductive film. By sandwiching the ACF between the pads and crimping the liquid ejection chip 10A and the wiring substrate 20, metal particles inside the ACF come into contact, creating a conductive path and achieving electrical connection. Then, to insulate and protect the electrical connection formed by this bonding, a liquid sealing material is supplied to bury the electrical connection. The liquid sealing material can be supplied in the same manner as in Example 1. The sealing material is then cured to obtain a sealing portion 40A (sealing portion forming step). This allows the liquid ejection unit 1A to be obtained (see FIG. 11(b)).

[0043] <Advantages of the liquid ejection unit and its manufacturing method according to this embodiment> According to this embodiment, the second surface 10AU, which is the side surface of the liquid ejection chip 10A, has a step in an area where the sealing portion 40A may come into contact. This second surface 10AU is configured to have a first step protruding from the surface adjacent to the first surface 10AS and a second step protruding from the surface adjacent to the third surface 10AT. This results in a first ridge R1 and a second ridge R2 on either side of the protruding portion of the second surface 10AU, and a third ridge R3 at the boundary between the second surface 10AU and the third surface 10AT.

[0044] Therefore, in the step of supplying the liquid sealing material, the liquid sealing material flows along the second surface 10AU but stops at the position of the first ridgeline R1. The reason for this is as explained in Example 1. Even if the sealing material overruns the first ridgeline R1, it stops at the second ridgeline R2. Furthermore, even if the sealing material overruns the second ridgeline R2, it stops at the third ridgeline R3. Therefore, adhesion of the sealing material to the third surface 10T can be suppressed. Note that in this example, as shown in FIG. 11(b), the liquid sealing material is supplied up to the first ridgeline R1. However, since it is sufficient to embed the electrical connection portion with the sealing material, it is not necessarily required to supply the liquid sealing material up to the first ridgeline R1. That is, in the sealing portion forming step, it is sufficient to supply the sealing material to at least a portion of the second surface 10AU on the side connected to the first surface 10AS.

[0045] As described above, the present embodiment can also achieve the same effect as the first embodiment. In this embodiment, the large number of ridges allows the flow of the sealing material to be more effectively stopped. Furthermore, in this embodiment, the first step (the length x of the step surface) is configured to be larger than the second step (the length y of the step surface) (see FIG. 11(a)). By increasing the first step protruding from the surface adjacent to the first surface 10AS in this way, the spatial area enclosed between the surface of the second surface 10AU adjacent to the first surface 10AS and the step surface of the first step can be enlarged. This allows a large amount of liquid sealing material to be received in this spatial area. Meanwhile, the spatial area enclosed between the surface of the second surface 10AU adjacent to the third surface 10AT and the step surface of the second step is kept small. By doing so, it is possible to suppress a decrease in strength in the vicinity of the protruding portion on the second surface 10AU.

[0046] The step formed on the second surface 10AU is configured so as not to reach the position directly behind the electrical connection portion of the liquid ejection chip 10A. In other words, if the distance from the tip of the protrusion on the second surface 10AU to the electrical connection portion (pad 12) in the planar direction of the first surface 10AS is z, then the relationship z>x>y is satisfied. This makes it possible to prevent the liquid ejection chip 10 from being damaged by impact when installing the electrical connection portion, for example.

[0047] In this embodiment, two steps are provided to form three ridges, but the number of steps and ridges is not particularly limited. More steps and ridges may be provided depending on the viscosity and wettability of the liquid sealing material.

[0048] Example 3 A liquid discharge unit according to a third embodiment of the present invention and a manufacturing method thereof will be described with reference to Figures 12 to 14. Figures 12 and 13 are manufacturing process diagrams for the liquid discharge unit according to the third embodiment of the present invention, and Figure 14 is a schematic diagram of the liquid discharge unit according to the third embodiment of the present invention. In both figures, the vicinity of the electrical connection portion is shown in a schematic cross-sectional view.

[0049] First, a method for manufacturing the liquid ejection chip 10B will be described. A plurality of liquid ejection chips 10B are manufactured from a wafer 10X serving as a base material, such as a silicon substrate. The formation of ejection ports and the attachment of pads 12 to the wafer 10X are as described in Example 1. The surface of the wafer 10X to which the pads 12 are attached (the surface on which electrical connection parts will later be provided) is referred to as the "first surface 10XS," and the surface behind it is referred to as the "third surface 10XT." Furthermore, the surface of the first substrate 10B1 in the liquid ejection chips 10B, which are subsequently cut from the wafer 10X and into which the pads 12 are attached (the surface on which electrical connection parts will later be provided) is referred to as the "first surface 10B1S," and the surface behind it is referred to as the "third surface 10B1T."

[0050] In this example, a wafer other than the wafer 10X is also used. This wafer is subjected to dry etching to produce a second substrate 10B2 having steps on its side surface. The second substrate 10B2 is then bonded (see FIG. 12(b)) to the first surface 10XS of the wafer 10X (see FIG. 12(a)) on which the discharge ports and the like are formed as described above.

[0051] Thereafter, the wafer 10X is cut by laser dicing at the midpoint between adjacent pads 12 (division process). This results in individual liquid ejection chips 10B (see FIG. 13(a)). In this embodiment, the liquid ejection chip 10B includes a first substrate 10B1 and a second substrate 10B2 that are bonded together to form an integrated chip. A step is formed on the side of the second substrate 10B2. This side intersects with the first surface 10B1S and will be referred to as the "second surface 10B2U" hereinafter. In this embodiment, the second surface 10B2U is located on the opposite side of the first surface 10B1S from the third surface 10B1T.

[0052] Next, a separately manufactured wiring substrate 20 is bonded to the first substrate 10B1 of the liquid ejection chip 10B with an adhesive. Then, the pads 22 of the wiring substrate 20 and the pads 12 of the liquid ejection chip 10B are electrically connected by wire bonding (connection step). That is, both ends of the wire 50 are connected to the pads 12 and 22, respectively, to provide an electrical connection (see FIG. 13(b)).

[0053] Thereafter, a liquid sealing material is supplied to bury the electrical connection portions in order to insulate and protect the electrical connection portions. The same method as in Example 1 can be used to supply the liquid sealing material. Thereafter, the sealing material is hardened to obtain the sealing portion 40B (sealing portion forming step). This allows the liquid discharge unit 1B to be obtained (see FIG. 14).

[0054] <Advantages of the liquid ejection unit and its manufacturing method according to this embodiment> According to this embodiment, the second surface 10B2U, which is the side surface of the second substrate 10B2 in the liquid ejection chip 10B, has a step in the area where the sealing portion 40B can come into contact, thereby providing a first ridge portion R1 and a second ridge portion R2.

[0055] Therefore, in the step of supplying the liquid sealing material, the liquid sealing material flows along the second surface 10B2U but stops at the position of the first ridge portion R1. The reason for this is as explained in Example 1. Furthermore, even if the sealing material overruns the first ridge portion R1, it stops at the second ridge portion R2. This prevents the sealing material from adhering to the surface of the second substrate 10B2 opposite the bonding surface with the first substrate 10B1. Note that in this example, as shown in FIG. 14 , the liquid sealing material is supplied up to the first ridge portion R1. However, since it is sufficient to embed the electrical connection portion with the sealing material, it is not necessarily required to supply the liquid sealing material up to the first ridge portion R1. In other words, in the sealing portion forming step, it is sufficient to supply the sealing material to at least a portion of the second surface 10B2U on the side connected to the first surface 10B1S.

[0056] As described above, this embodiment can also achieve the same effects as those of the first embodiment. In the first and second embodiments, the third surfaces of the liquid ejection chips in the liquid ejection unit are bonded to the support member 30. However, in this embodiment, the surface of the second substrate 10B2 opposite to the surface bonded to the first substrate 10B1 is bonded to the support member 30. This achieves the same effects as those of the above embodiments. The configuration of this embodiment may also include bonding the third surfaces of the liquid ejection chips to the support member 30. Even in such cases, a configuration may be adopted in which a sheet for recording an image is transported to the surface of the second substrate 10B2 opposite to the surface bonded to the first substrate 10B1. In this case, the ability to prevent the sealing material from adhering to the surface opposite to the surface bonded to the first substrate 10B1 has the advantage that the cured sealing material does not interfere with the transport of the sheet.

[0057] (others) In the above-described Example 2, the second surface has a first step protruding from the surface adjacent to the first surface and a second step protruding from the surface adjacent to the third surface. As a variation of this, a configuration in which the second surface only has a step protruding from the surface adjacent to the third surface can also be adopted. [Explanation of symbols]

[0058] 1, 1A, 1B... liquid ejection unit 10, 10A, 10B... liquid ejection chip 11... ejection port 20... wiring substrate 40, 40A, 40B... sealing portion 10S, 10AS, 10B1S... first surface 10U, 10AU, 10B2U... second surface 10T, 10AT, 10B1T... third surface

Claims

1. a liquid ejection substrate having an ejection port for ejecting liquid; a wiring substrate electrically connected to the liquid ejection substrate by an electrical connection portion; a sealing portion in which the electrical connection portion is embedded; A liquid ejection unit comprising: the liquid ejection substrate has a first surface on which the electrical connection portion is provided, a second surface intersecting the first surface, and a third surface on the back side of the first surface; the second surface has a step including a first step surface connected to the first surface, a second step surface connected to the third surface, and a third step surface provided on the opposite side of the third surface and connecting the first step surface and the second step surface, The liquid discharge unit, wherein the first step surface and the third step surface of the steps are included in an area that can come into contact with the sealing portion.

2. The liquid ejection substrate is a liquid flow path communicating with the discharge port; an element that converts an electrical signal sent from the wiring board into thermal energy to eject heated liquid from the ejection port; The liquid ejection unit according to claim 1 , further comprising:

3. When the step is a first step, The liquid ejection unit described in claim 1 or 2, characterized in that the second step surface has a second step including a fourth step surface connected to the third step surface, a fifth step surface connected to the third surface, and a sixth step surface provided on the opposite side of the third step surface that connects the fourth step surface and the fifth step surface.

4. 4. The liquid ejection unit according to claim 3, wherein the first step is larger than the second step.

5. 5. The liquid ejection unit according to claim 1, wherein the step formed on the second surface does not reach a position directly behind the electrical connection portion on the liquid ejection substrate. knit.

6. a connecting step of electrically connecting a liquid ejection substrate having ejection ports for ejecting liquid to a wiring substrate; a sealing portion forming step of embedding the electrical connection portion obtained in the connecting step with a liquid sealing material and hardening the material to form a sealing portion; and The liquid ejection substrate has a first surface on which the electrical connection portion is provided, a second surface intersecting the first surface, and a third surface on the back side of the first surface, and the second surface has steps including a first step surface connecting to the first surface, a second step surface connecting to the third surface, and a third step surface provided on the opposite side of the third surface that connects the first step surface and the second step surface, and in the sealing portion forming process, the sealing material is supplied to at least a portion of the second surface on the side that connects to the first surface.

7. 7. The method for manufacturing a liquid discharge unit according to claim 6, further comprising a dividing step of dividing the base material, wherein the second step surface of the step is formed in the dividing step.

8. 8. The method for manufacturing a liquid discharge unit according to claim 7, wherein in the dividing step, the first step surface and the third step surface of the steps are formed by blade dicing.

9. 8. The method for manufacturing a liquid discharge unit according to claim 7, wherein in the dividing step, the first step surface and the third step surface of the steps are formed by dry etching.

Images