Liquid ejection head

Abstract

To provide a liquid discharge head which reduces stress generated in a discharge port formation member, and has high reliability.SOLUTION: A liquid discharge head 20 has: a substrate 1; a discharge port formation member 6 which has a discharge port surface 6a where a plurality of discharge ports 8 for discharging liquid are formed, is joined to the substrate 1 on a joint surface 6b opposite to the discharge port surface 6a, and has a groove 7 penetrating in a thickness direction Z formed around the plurality of discharge ports 8; and a resin film 5 provided between the substrate 1 and the discharge port formation member 6, wherein the substrate 1 has a metal film 9 formed along the groove 7 at a position overlapping the groove 7 in plan view, and the groove 7 has a part 72 between the discharge port surface 6a and the joint surface 6b in the thickness direction Z wider than other parts 71 and 73.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a liquid ejection head. [Background technology]

[0002] In a liquid ejection head that ejects liquid such as ink from ejection ports to record an image on a recording medium, if stress occurs in the ejection port forming member, the bond with the substrate may peel off, leading to a decrease in reliability. Therefore, in order to relieve such stress and suppress the peeling of the ejection port forming member, a technique is known in which a groove is formed in the ejection port forming member in the thickness direction at a position surrounding a plurality of ejection ports formed therein. Patent Document 1 describes a technique in which the groove is divided into two regions in the thickness direction of the ejection port forming member, the edge of the region on the bonding surface side with the substrate is formed in a sawtooth shape in a plan view, and the edge of the region on the ejection port surface side where the ejection ports are formed is formed in a straight or curved shape in a plan view. This not only distributes and relieves the stress generated in the ejection port forming member, but also makes it difficult for foreign matter such as paper powder to get caught in the groove during a wiping operation to remove liquid attached to the ejection port surface, and also reduces the stress caused by the wiping operation. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5183187 Summary of the Invention [Problem to be solved by the invention]

[0004] Generally, a resin film is provided between the substrate and the ejection port forming member to improve the adhesion between them, but the bond between this resin film and the substrate may peel off due to stress generated in the ejection port forming member. However, the technology described in Patent Document 1 does not take into consideration how to prevent the peeling of the resin film. SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a highly reliable liquid ejection head that reduces the stress generated in the ejection port forming member. [Means for solving the problem]

[0005] In order to achieve the above-mentioned object, the liquid ejection head of the present invention comprises a substrate, an ejection port surface on which a plurality of ejection ports for ejecting liquid are formed, the ejection port surface being joined to the substrate at a joining surface opposite the ejection port surface ... In one embodiment, the groove is formed such that a portion between the discharge port surface and the joint surface in the thickness direction is wider than the other portion, or the groove is composed of a first groove portion adjacent to the joint surface in the thickness direction, a second groove portion adjacent to the first groove portion in the thickness direction, and a third groove portion adjacent to the second groove portion and the discharge port surface in the thickness direction, and at least one of the following is true: the inner peripheral wall surface of the second groove portion is located more inward than the inner peripheral wall surface of the first groove portion and the inner peripheral wall surface of the third groove portion, or the outer peripheral wall surface of the second groove portion is located more outward than the outer peripheral wall surface of the first groove portion and the outer peripheral wall surface of the third groove portion. In another embodiment, the region of the discharge port forming member including a portion of the groove is formed thinner than the other region, or the discharge port forming member has a notch portion formed from the discharge port surface to the side surface that communicates with the groove. Effect of the Invention

[0006] According to the present invention, it is possible to provide a highly reliable liquid ejection head by reducing the stress generated in the ejection port forming member. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a perspective view of a liquid ejection head according to a first embodiment. [Diagram 2] 1A and 1B are an enlarged plan view and a cross-sectional view of a liquid ejection head according to a first embodiment. [Diagram 3] 2A to 2C are diagrams illustrating a method for manufacturing the liquid ejection head according to the first embodiment. [Figure 4] 5A and 5B are an enlarged plan view and a cross-sectional view of a liquid ejection head according to a second embodiment. [Diagram 5] 6A to 6C are diagrams illustrating a method for manufacturing a liquid ejection head according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description, components having the same functions are given the same reference numbers in the drawings, and the description of such components may be omitted.

[0009] (First embodiment) FIG. 1 is a perspective view of a liquid ejection head according to a first embodiment of the present invention. The liquid ejection head 20 ejects liquid such as ink to record an image on a recording medium, and includes a substrate 1 and an ejection port forming member 6. The substrate 1 is provided with a plurality of energy generating elements 2 that generate energy used to eject the liquid. The plurality of energy generating elements 2 are arranged in two rows at a predetermined pitch along the longitudinal direction X of the rectangular substrate 1, and a supply path 3 penetrating the substrate 1 is opened between them. Note that a connection terminal 4 for electrical connection to the outside is also formed at an end of the substrate 1 in the longitudinal direction X. The substrate 1 is formed of, for example, silicon, and the main surface is preferably a (100) plane or a crystal plane equivalent thereto, and the thickness is preferably 580 to 750 μm.

[0010] The discharge port forming member 6 has a discharge port surface 6a in which a plurality of discharge ports 8 for discharging liquid are formed, and is joined to the substrate 1 at a joining surface 6b opposite to the discharge port surface 6a. The discharge port forming member 6 is formed with a plurality of pressure chambers 12 each of which communicates with the discharge port 8 and also communicates with the supply path 3 of the substrate 1, and the plurality of discharge ports 8 are provided at positions corresponding to the plurality of energy generating elements 2. The liquid in the pressure chambers 12 can be bubbled and discharged from the discharge ports 8 by the energy generated by the energy generating elements 2. As the energy generating elements 2, in addition to heat generating elements (heaters), piezoelectric elements (piezo elements) that generate pressure by deforming the walls of the pressure chambers 12 to discharge the liquid can also be used. In addition, the discharge port forming member 6 is formed with grooves 7 penetrating in the thickness direction around the plurality of discharge ports 8. The detailed configuration and function of the grooves 7 will be described later.

[0011] The discharge port forming member 6 is required to have high mechanical strength as a structural material, adhesion to the substrate 1 as the base, and liquid resistance such as ink resistance, and at the same time, resolution for patterning fine patterns such as the discharge port 8 and the groove 7 described later is required. Examples of materials that satisfy these characteristics include cationic polymerization type epoxy resin compositions. Examples of epoxy resins include reaction products of bisphenol A and epichlorohydrin, reaction products of bromobisphenol A and epichlorohydrin, and reaction products of phenol novolac or o-cresol novolac and epichlorohydrin. In addition, the epoxy resins described above preferably have an epoxy equivalent of 2000 or less, more preferably 1000 or less. As a photocationic polymerization initiator for curing the epoxy resin, a compound that generates an acid by irradiation with light can be used, and for example, an aromatic sulfonium salt or an aromatic iodonium salt can be used. In addition, a wavelength sensitizer such as SP-100 (trade name) manufactured by ADEKA Corporation may be added as necessary.

[0012] Between the substrate 1 and the discharge port forming member 6, a resin film 5 is provided to improve the adhesion between them. Examples of materials for the resin film 5 include polyetheramide resin. In addition, between the substrate 1 and the resin film 5, a first metal film 9 is provided as a countermeasure against electrostatic discharge (ESD). The first metal film 9 is provided along the groove 7 formed in the discharge port forming member 6 at a position overlapping the groove 7 in a plan view, and specifically, is provided in a rectangular frame shape corresponding to the groove 7 provided in a frame shape so as to surround a plurality of discharge ports 8. Although not shown, the first metal film 9 is also provided at a position covering the energy generating element 2. The first metal film 9 provided at this position functions as a cavitation-resistant film to protect the energy generating element 2 from mechanical shock (cavitation) that occurs when bubbles grow and disappear during liquid discharge. Examples of materials for the first metal film 9 include SiN, SiC, Ta, and Ir. In addition, although not shown in FIG. 1, a second metal film 10 is provided between the substrate 1 and the first metal film 9 to protect the wiring layer formed on the substrate 1 from liquids such as ink.

[0013] Here, the detailed configuration and function of the grooves formed in the ejection port forming member of this embodiment will be described with reference to Fig. 2. Fig. 2(a) is an enlarged plan view of the area surrounded by the dashed line in Fig. 1, and Fig. 2(b) and Fig. 2(c) are cross-sectional views taken along lines AA and BB in Fig. 2(a), respectively. The discharge port forming member 6 has a different thickness to ensure the desired discharge characteristics according to the type of liquid to be discharged, and some of them have a thickness of about 70 μm, for example. When the thickness of the discharge port forming member 6 increases and the volume increases accordingly, the stress generated in the discharge port forming member 6 also increases, making it more likely to peel off from the substrate 1. In addition, due to such stress, the resin film 5 may also peel off from the substrate 1, and in particular, peeling may occur from the substrate 1 in the region of the resin film 5 that overlaps with the first metal film 9 in a plan view. This is because the adhesive force between the resin film 5 and the first metal film 9 is weaker than the adhesive force between the resin film 5 and the second metal film 10. Note that the plan view here means that the substrate 1 and the discharge port forming member 6 are viewed from the thickness direction.

[0014] Therefore, in this embodiment, in order to reduce the stress around the groove 7 of the ejection port forming member 6, a part of the groove 7 in the thickness direction Z of the ejection port forming member 6 (a part between the ejection port surface 6a and the joint surface 6b) is formed wider than the other part. Specifically, the groove 7 has a first groove portion 71 adjacent to the joint surface 6b in the thickness direction Z, a second groove portion 72 adjacent to the first groove portion 71 in the thickness direction Z, and a third groove portion 73 adjacent to the second groove portion 72 and the ejection port surface 6a in the thickness direction Z. The width of the second groove portion 72 is larger than the width of the first groove portion 71 and is larger than the width of the third groove portion 73. In other words, the second groove portion 72 has an inner peripheral side wall surface 72a located on the inner peripheral side of the inner peripheral side wall surface 71a of the first groove portion 71 and the inner peripheral side wall surface 73a of the third groove portion 73, and an outer peripheral side wall surface 72b located on the outer peripheral side of the outer peripheral side wall surface 71b of the first groove portion 71 and the outer peripheral side wall surface 73b of the third groove portion 73. Note that the width here means the distance between the inner peripheral side wall surface and the outer peripheral side wall surface, and when the distance between the two varies as described later, it means the distance at the widest part. In addition, the second groove portion 72 is provided so as to cover the entire first metal film 9 in a plan view, that is, the inner peripheral side wall surface 72a is located on the inner peripheral side of the inner peripheral edge 9a of the first metal film 9, and the outer peripheral side wall surface 72b is located on the outer peripheral side of the outer peripheral edge 9b of the first metal film 9.

[0015] With this configuration, in the region of the ejection port forming member 6 that overlaps with the first metal film 9 in a plan view, the volume per unit area in a plan view (hereinafter also simply referred to as "volume") is smaller than other regions, thereby reducing stress generated in the ejection port forming member 6. As a result, peeling of the ejection port forming member 6 and the resin film 5 from the substrate 1 can be suppressed, particularly in the region that overlaps with the first metal film 9 in a plan view. The depth of the first groove portion 71, i.e., the thickness of the portion of the ejection port forming member 6 that corresponds to the first groove portion 71, greatly affects the stress generated in the ejection port forming member 6, and greatly affects the peeling of the ejection port forming member 6. Therefore, in order to reduce the stress generated in the ejection port forming member 6, it is preferable that the depth d1 of the first groove portion 71 is as small as possible. In this embodiment, the maximum thickness t max In addition, if the depth of the second groove portion 72, i.e., the thickness of the portion of the ejection port forming member 6 corresponding to the second groove portion 72, becomes too large, the rigidity of the ejection port forming member 6 decreases, and the flatness of the ejection port surface 6a may not be ensured. Therefore, in this embodiment, the sum of the depth d1 of the first groove portion 71 and the depth d2 of the second groove portion 72 is also set to be less than one-third of the maximum thickness t max is less than one-third.

[0016] The inner peripheral wall surface 71a of the first groove portion 71 is located on the outer peripheral side of the inner peripheral edge 9a of the first metal film 9, but the end portion on the bonding surface 6b side can be a starting point for peeling off the ejection port forming member 6 or the resin film 5 when stress is generated in the ejection port forming member 6. Similarly, the outer peripheral wall surface 71b of the first groove portion 71 is located on the inner peripheral side of the outer peripheral edge 9b of the first metal film 9, but the end portion on the bonding surface 6b side can also be a starting point for peeling off the ejection port forming member 6 or the resin film 5 when stress is generated in the ejection port forming member 6. Therefore, in order to disperse and relieve such stress, it is preferable that the inner peripheral wall surface 71a and the outer peripheral wall surface 71b of the first groove portion 71 are formed in a sawtooth shape in a plan view as shown in the figure. In addition, it is preferable that both the inner peripheral wall surface 73a and the outer peripheral wall surface 73b of the third groove portion 73 are formed in a straight or curved shape in a plan view as shown in the drawing. This makes it possible to prevent foreign matter such as paper powder from getting caught in the groove 7 during a wiping operation to remove liquid adhering to the discharge port surface 6a, and also reduces stress caused by the wiping operation.

[0017] From the viewpoint of reducing the stress around the groove 7 of the discharge port forming member 6, the inner peripheral wall surface 72a of the second groove portion 72 does not necessarily have to be located on the inner peripheral side of the inner peripheral edge 9a of the first metal film 9. Alternatively, the outer peripheral wall surface 72b of the second groove portion 72 does not necessarily have to be located on the outer peripheral side of the outer peripheral edge 9b of the first metal film 9. Furthermore, even if the second groove portion 72 is not wider on both sides in the width direction than the first and third groove portions 71 and 73, it is expected that the second groove portion 72 can be effective to a certain extent in reducing the stress around the groove 7 of the discharge port forming member 6. However, in order to reliably and effectively suppress peeling of the discharge port forming member 6 and the resin film 5 in the region overlapping with the first metal film 9 in a plan view, it is preferable that the second groove portion 72 is wider on both sides in the width direction than the first and third groove portions 71 and 73, as shown in the figure. In addition, it is preferable that the inner circumferential wall surface 72a of the second groove portion 72 is located more inward than the inner circumferential edge 9a of the first metal film 9, and that the outer circumferential wall surface 72b is located more outward than the outer circumferential edge 9b of the first metal film 9. In the illustrated example, the cross section of groove 7 is symmetrical with respect to the center in the width direction, and its center approximately coincides with the center in the width direction of first metal film 9, but the shape and arrangement of groove 7 are not limited to this. In other words, the cross section of groove 7 does not have to be symmetrical with respect to the center in the width direction, and its center does not have to coincide with the center in the width direction of first metal film 9.

[0018] 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(f) are schematic diagrams of the liquid ejection head in each step of the manufacturing method of this embodiment, with the left diagram corresponding to the enlarged plan view of Fig. 2(a) and the right diagram corresponding to the cross-sectional view taken along line CC of Fig. 2(a).

[0019] First, a rectangular substrate 1 is prepared, which has on its surface the energy generating elements 2, the second metal film 10, and the first metal film 9. As the substrate 1, for example, a silicon substrate having a thickness of 725 μm is used. Next, for example, a polyetheramide resin is formed on the substrate 1, and then patterned to form a resin film 5 having a desired pattern, as shown in FIG. 3(a). The patterning is performed, for example, by laminating a dry film resist or applying a resist by spin coating, and then performing dry etching using a positive resist as a mask. The positive resist is formed, for example, by exposure to ultraviolet light (deep-UV light) and patterning by development. The thickness of the resin film 5 is, for example, 2 μm.

[0020] Next, as shown in FIG. 3(b), a first resin layer 13 is formed on the resin film 5, which will be a portion corresponding to the first groove portion 71 of the discharge port forming member 6. Specifically, a negative photosensitive resin composition is applied to a thickness of 10 μm by spin coating, and then exposed to ultraviolet light or the like, followed by post-exposure bake (PEB) and development to form the first resin layer 13 having a desired pattern. The exposed portion may be heated to a degree that allows curing to be achieved to the extent that the migration of acid is suppressed, and the temperature for this purpose is preferably about 80 to 95° C., although it depends on the components of the negative photosensitive resin. An example of a negative photosensitive resin composition is CR-2.0 (product name) manufactured by ADEKA Corporation. Next, a soluble resin is applied onto the resin film 5 and the first resin layer 13 by spin coating, and then patterning is performed to form a mold material 14 for forming the pressure chambers 12 and the first and second grooves 71, 72 in a desired pattern, as shown in FIG. 3(c). The patterning is performed, for example, by exposure to ultraviolet light (deep-UV light) and development. Examples of the material for the mold material 14 include polymethyl isopropenyl ketone such as ODUR-1010 (product name) manufactured by Tokyo Ohka Kogyo Co., Ltd. The thickness of the mold material 14 is, for example, 20 μm.

[0021] Next, the negative photosensitive resin composition is applied multiple times by spin coating onto the mold material 14 until the height from the surface of the substrate 1 reaches about 70 μm, and as shown in FIG. 3(d), a second resin layer 15 that will be the remaining part of the discharge port forming member 6 is formed. After that, exposure to ultraviolet light or the like and PEB are performed to form a pattern of the discharge port 8 and the third groove portion 73 in the second resin layer 15. The photosensitive resin composition of the second resin layer 15 can be selected from those listed above as the material of the discharge port forming member 6, but it is preferable that the base resin and the polymerization initiator are the same as those of the first resin layer 13. In particular, it is preferable that the compound species contained in each negative photosensitive resin composition are the same. However, even if the compound species are the same, the respective compounding ratios do not need to be the same, and the concentration relative to the solvent may be different when applying by the spin coating method. Next, development is performed to remove the unexposed portions of the second resin layer 15, thereby forming the ejection ports 8 and the third grooves 73, as shown in FIG. 3(e).

[0022] Next, as shown in FIG. 3(f), after the supply path 3 is formed in the substrate 1, the mold material 14 is removed to form the ejection port forming member 6 having the pressure chamber 12 and the groove 7. Specifically, first, a blind hole (not shown) is formed on the back surface of the substrate 1, and then etching is performed from the back surface side for a dozen hours using, for example, TMAH (tetramethylammonium hydroxide) heated to 80° C., to form the supply channel 3 in the substrate 1. In addition to TMAH, strong alkaline solutions such as KOH and NaOH can be used as the etching solution. Thereafter, the second metal film 10 in the portion facing the supply channel 3 is removed by dry etching, and then the entire surface of the substrate 1 is exposed to ultraviolet light (deep-UV light) through the discharge port forming member 6 from the front surface side of the substrate 1. Then, dissolution and drying are performed, and the mold material 14 is removed, thereby forming the discharge port forming member 6 having the pressure chamber 12 and the groove 7. In order to more reliably dissolve the material in a short time, ultrasonic treatment may be performed during dissolution. Thereafter, the substrate 1 is cut into individual pieces by dicing, and then electrically connected to the outside, thereby completing the liquid ejection head 20 shown in FIG.

[0023] Second embodiment Fig. 4(a) is an enlarged plan view of a liquid ejection head according to a second embodiment of the present invention, and corresponds to Fig. 2(a). Fig. 4(b) and Fig. 4(c) are cross-sectional views taken along lines DD and EE in Fig. 4(a), respectively. Hereinafter, the same components as those in the first embodiment will be denoted by the same reference numerals in the drawings, and their description will be omitted, and only the components different from the first embodiment will be described.

[0024] In this embodiment, in order to reduce stress around the groove 7 of the ejection port forming member 6, a notch 16 that communicates with the groove 7 is formed in a part of the ejection port forming member 6, specifically, at both ends in the longitudinal direction X of the rectangular plate-like ejection port forming member 6. The notch 16 is formed in a rectangular shape in a plan view from the ejection port surface 6a to the side, and has three side surfaces 16a to 16c that are perpendicular to each other, and the first and second side surfaces 16a, 16b that face each other are formed parallel to the longitudinal direction X of the ejection port forming member 6. With this configuration, the region of the ejection port forming member 6 including a part of the groove 7 can be made thinner than the other regions. Therefore, in this embodiment, the volume of the region of the ejection port forming member 6 overlapping with the first metal film 9 in a plan view is smaller than the volume of the other regions, so that the stress generated in the ejection port forming member 6 can be reduced. In particular, the volume of the ejection port forming member 6 is larger at the end of the longitudinal direction X of the ejection port forming member 6 than at the end of the lateral direction perpendicular thereto, and peeling of the ejection port forming member 6 and the resin film 5 is likely to occur. By providing the cutout portion 16 in this region, peeling of the ejection port forming member 6 and the resin film 5 can be more effectively suppressed.

[0025] The cutout 16 is preferably formed in the discharge port forming member 6 such that a part of the inner peripheral edge 9a of the first metal film 9 is located inside the third side surface 16c connecting the first and second side surfaces 16a, 16b in a plan view. The cutout 16 is preferably formed in the discharge port forming member 6 such that a part of the outer peripheral edge 9b of the first metal film 9 is located inside the first and second side surfaces 16a, 16b in a plan view. This makes it possible to reliably and effectively suppress peeling of the discharge port forming member 6 and the resin film 5 in the region overlapping with the first metal film 9 in a plan view. In this embodiment, it is also preferable that the depth of the groove 7, that is, the thickness t1 of the portion of the ejection port forming member 6 that has become thin due to the formation of the notch portion 16, is as thin as possible. max It is preferable that the thickness is less than one third of the thickness.

[0026] The inner peripheral wall surface 7a of the groove 7 is located on the outer peripheral side of the inner peripheral edge 9a of the first metal film 9, but the end portion on the bonding surface 6b side can be a starting point for peeling off the ejection port forming member 6 or the resin film 5 when stress is generated in the ejection port forming member 6. Similarly, the outer peripheral wall surface 7b of the groove 7 is located on the inner peripheral side of the outer peripheral edge 9b of the first metal film 9, but the end portion on the bonding surface 6b side can also be a starting point for peeling off the ejection port forming member 6 or the resin film 5 when stress is generated in the ejection port forming member 6. Therefore, in order to disperse and mitigate such stress, it is preferable that the inner peripheral wall surface 7a and the outer peripheral wall surface 1b of the groove 71 are formed in a sawtooth shape in a plan view as shown in the figure. In addition, it is preferable that the side surfaces 16a to 16c of the cutout portion 16 are each formed linearly in a plan view as shown in the drawing. This makes it possible to prevent foreign matter such as paper powder from getting caught in the cutout portion 16 during a wiping operation to remove liquid adhering to the ejection port surface 6a, and also reduces stress caused by the wiping operation.

[0027] Here, the manufacturing method of the liquid ejection head of this embodiment will be briefly described with reference to Fig. 5. Fig. 5(a) to Fig. 5(f) are schematic diagrams of the liquid ejection head in each step of the manufacturing method of this embodiment, with the left figure corresponding to the enlarged plan view of Fig. 4(a) and the right figure corresponding to the cross-sectional view taken along line FF in Fig. 4(a). Note that, unless otherwise specified, in the following description, the same materials as in the first embodiment are used for the same configuration as in the first embodiment.

[0028] First, as in the first embodiment, a substrate 1 having an energy generating element 2, a second metal film 10 and a first metal film 9 on its surface is prepared, and a resin film 5 having a desired pattern is formed on the substrate 1 using procedures and conditions similar to those of the process shown in Figure 3(a). Next, as shown in FIG. 5(a), a mold material 14 for forming pressure chambers 12 and grooves 7 is formed on the resin film 5 using the same procedure and conditions as in the step shown in FIG. 3(c). Next, as shown in FIG. 5(b), a first resin layer 13 that will become part of the discharge port forming member 6 is formed on the resin film 5 and the mold material 14 under the same procedure and conditions as in the step shown in FIG. 3(b). Then, exposure to ultraviolet light or the like and PEB are performed to form a pattern of the area of ​​the groove 7 where the notch 16 is to be formed. Thereafter, as shown in FIG. 5(c), a second resin layer 15 that will become the remaining part of the discharge port forming member 6 is formed on the first resin layer 13 under the same procedure and conditions as in the step shown in FIG. 3(d). Then, exposure to ultraviolet light or the like and PEB are performed to form a pattern of the discharge port 8 and the remaining groove 7 in the second resin layer 15.

[0029] Next, development is performed to remove the unexposed portions of the first and second resin layers 13, 15, as in the process shown in Figure 3(e), thereby forming the discharge port 8, the cutout portion 16, and part of the groove 7, as shown in Figure 5(d). Next, using the third harmonic of a YAG laser (wavelength 355 nm), blind holes 11 are formed in the substrate 1 as shown in Fig. 5(e). Thereafter, as shown in Fig. 5(f), supply paths 3 are formed in the substrate 1 under the same procedure and conditions as in the step shown in Fig. 3(f), and then the mold material 14 is removed to form the ejection port forming member 6 having the pressure chambers 12 and grooves 7. The substrate 1 is then cut into individual pieces by dicing, and the individual pieces are then electrically connected to the outside to complete the liquid ejection head 20 shown in Fig. 1. [Explanation of symbols]

[0030] 1 Board 5 Resin film 6. Discharge port forming member 7 grooves 9 First metal film 20 Liquid ejection head

Claims

1. A substrate; an ejection port forming member having an ejection port surface on which a plurality of ejection ports for ejecting liquid are formed, the ejection port forming member being joined to the substrate at a joining surface opposite to the ejection port surface, the ejection port forming member having a frame-shaped groove formed therein and penetrating in a thickness direction at a position surrounding the plurality of ejection ports; a resin film provided between the substrate and the ejection port forming member, a metal film formed in a frame shape at a position where the substrate overlaps with the groove in a plan view; The liquid ejection head is characterized in that a portion of the groove between the ejection port surface and the joint surface in the thickness direction is formed to be wider than the other portion.

2. A substrate; an ejection port forming member having an ejection port surface on which a plurality of ejection ports for ejecting liquid are formed, the ejection port forming member being joined to the substrate at a joining surface opposite to the ejection port surface, the ejection port forming member having a frame-shaped groove formed therein and penetrating in a thickness direction at a position surrounding the plurality of ejection ports; a resin film provided between the substrate and the ejection port forming member, a metal film formed in a frame shape at a position where the substrate overlaps with the groove in a plan view; the groove includes a first groove portion adjacent to the bonding surface in the thickness direction, a second groove portion adjacent to the first groove portion in the thickness direction, and a third groove portion adjacent to the second groove portion and the ejection port surface in the thickness direction, A liquid ejection head characterized in that at least one of an inner peripheral wall surface of the second groove portion is located more inward than the inner peripheral wall surface of the first groove portion and the inner peripheral wall surface of the third groove portion, and an outer peripheral wall surface of the second groove portion is located more outward than the outer peripheral wall surface of the first groove portion and the outer peripheral wall surface of the third groove portion.

3. 3. The liquid ejection head according to claim 2, wherein an inner wall surface of the second groove portion is located more inward than an inner wall surface of the first groove portion and an inner wall surface of the third groove portion, and an outer wall surface of the second groove portion is located more outward than an outer wall surface of the first groove portion and an outer wall surface of the third groove portion.

4. The liquid ejection head according to claim 3 , wherein an inner wall surface of the second groove portion is located on the inner side of the inner edge of the metal film, and an outer wall surface of the second groove portion is located on the outer side of the outer edge of the metal film.

5. The liquid ejection head according to claim 3 , wherein an inner peripheral wall surface and an outer peripheral wall surface of the first groove portion are formed in a sawtooth shape in a plan view.

6. The liquid ejection head according to claim 2 , wherein an inner peripheral wall surface and an outer peripheral wall surface of the third groove portion are formed in a straight line or a curved line in a plan view.

7. 7. The liquid ejection head according to claim 2, wherein the depth of the first groove portion is less than one-third of the maximum thickness of the ejection port forming member.

8. 8. The liquid ejection head according to claim 2, wherein a sum of a depth of the first groove portion and a depth of the second groove portion is less than ⅓ of a maximum thickness of the ejection port forming member.

9. A substrate; an ejection port forming member having an ejection port surface on which a plurality of ejection ports for ejecting liquid are formed, the ejection port forming member being joined to the substrate at a joining surface opposite to the ejection port surface, the ejection port forming member having a frame-shaped groove formed therein and penetrating in a thickness direction at a position surrounding the plurality of ejection ports; a resin film provided between the substrate and the ejection port forming member, a metal film formed in a frame shape at a position where the substrate overlaps with the groove in a plan view; A liquid ejection head, wherein a region of the ejection port forming member including a part of the groove is formed to be thinner than other regions.

10. A substrate; an ejection port forming member having an ejection port surface on which a plurality of ejection ports for ejecting liquid are formed, the ejection port forming member being joined to the substrate at a joining surface opposite to the ejection port surface, the ejection port forming member having a frame-shaped groove formed therein and penetrating in a thickness direction at a position surrounding the plurality of ejection ports; a resin film provided between the substrate and the ejection port forming member, a metal film formed in a frame shape at a position where the substrate overlaps with the groove in a plan view; The liquid ejection head is characterized in that the ejection port forming member has a notch portion formed from the ejection port surface to a side surface thereof, the notch portion communicating with the groove.

11. 11. The liquid ejection head according to claim 10, wherein the ejection port forming member is formed in a rectangular plate shape, and the notch portion is provided at an end portion in a longitudinal direction of the ejection port forming member.

12. A liquid ejection head as described in claim 11, wherein the cutout portion has first and second side surfaces facing each other and a third side surface connecting the first and second side surfaces, and the first and second side surfaces are formed parallel to the longitudinal direction of the ejection port forming member.

13. The liquid ejection head according to claim 12 , wherein the cutout portion is formed such that a part of an inner periphery of the metal film is located more inward than the third side surface in a plan view.

14. The liquid ejection head according to claim 12 or 13, wherein the cutout portion is formed such that a part of an outer periphery of the metal film is positioned more inward than the first and second side surfaces in a plan view.

15. The liquid ejection head according to claim 12 , wherein each of the side surfaces of the cutout portion is formed linearly in a plan view.

16. The liquid ejection head according to claim 10 , wherein an inner peripheral wall surface and an outer peripheral wall surface of the groove are formed in a sawtooth shape in a plan view.

17. 17. The liquid ejection head according to claim 10, wherein a thickness of the portion of the ejection port forming member where the cutout portion is formed is less than one third of a maximum thickness of the ejection port forming member.

18. A liquid ejection head as described in any one of claims 1 to 17, wherein the substrate has a plurality of energy generating elements at positions corresponding to the plurality of ejection ports, the energy generating elements generating energy used to eject liquid, and the metal film is formed from the same material as a cavitation-resistant film covering the plurality of energy generating elements.

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