Liquid discharge head and manufacturing method of liquid discharge head

Abstract

To provide a liquid discharge head having high electric reliability.SOLUTION: A liquid discharge head includes: a substrate; a diaphragm provided on one surface side of the substrate; a plurality of piezoelectric elements having a first electrode, a piezoelectric body and a second electrode in this order on a surface on an opposite side of the substrate in the diaphragm; first wiring which has an electric resistivity lower than that of the first electrode and is electrically connected to the first electrode; second wiring which has an electric resistivity lower than that of the first electrode and is electrically connected to the second electrode. A pad electrode formed by a layer which is the same as that of the first electrode is electrically connected to at least one of the first wiring and the second wiring. The pad electrode has a pad region to which a mounting electrode is joined so as to give an electric signal to the piezoelectric element from the outside and a connection region to which the wiring electrically connected to the pad electrode is joined.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a liquid ejection head and a method for manufacturing the liquid ejection head.

Background Art

[0002] As a liquid ejection head that ejects liquid onto a recording medium to perform recording, for example, a liquid ejection head is known in which a part of a pressure chamber communicating with a nozzle that ejects ink droplets is formed by a diaphragm. By deforming this diaphragm with a piezoelectric element, the ink in the pressure chamber can be pressurized to eject ink droplets from the nozzle. The piezoelectric element of such a liquid ejection head includes a piezoelectric film that is a film-type piezoelectric body, and electrodes (also referred to as an upper electrode and a lower electrode) formed so as to sandwich the piezoelectric film from above and below. By applying a voltage to the upper and lower electrodes to drive the piezoelectric film, the diaphragm is deformed by the piezoelectric element, and droplets (ink droplets) are ejected from the nozzle. At this time, the voltage required to sufficiently displace the piezoelectric film is several tens of volts. When forming the piezoelectric film using a semiconductor, it is necessary to apply a relatively high voltage as a semiconductor device.

[0003] In addition, in order to print high-definition images, the liquid ejection head is miniaturized, and a plurality of piezoelectric elements are arranged at high density. In recent years, the pitch corresponding to the arrangement direction of the nozzles of individual piezoelectric elements has become narrow and at high density, such as equivalent to 600 npi (nozzles per inch), equivalent to 1200 npi, equivalent to 2400 npi, etc. As the piezoelectric elements are arranged at high density, lead-out wirings electrically connected to the piezoelectric elements and pad electrodes for applying an electrical signal (drive signal) to the piezoelectric elements from the outside are arranged at high density. A flexible substrate or the like is mounted on the pad electrodes to connect to an external drive circuit and apply an electrical signal to the piezoelectric elements. As a method of mounting the flexible substrate, there is a mounting method using wire bonding. In addition, as a method of mounting the flexible substrate, there is a mounting method using ACF (anisotropic conductive film) or ACP (anisotropic conductive paste). As a method of mounting the flexible substrate, there is a mounting method using NCF (non-conductive film) or NCP (non-conductive paste). Incidentally, the mounting method using ACF or ACP is also referred to as ACF / ACP (Anisotropic Conductive Film / Paste). The mounting method using NCF or NCP is also referred to as NCF / NCP (Non Conductive Film / Paste).

[0004] Among a plurality of pad electrodes, when the pitch between adjacent pad electrodes becomes about 50 μm or less, from the viewpoint of the size of the first bond, the mounting method using wire bonding becomes difficult. In the case of the mounting method using wire bonding, countermeasures such as arranging the pad electrodes in a staggered pattern can be considered, but the possibility of short - circuiting between adjacent pad electrodes (bonding wires) increases. Also, as described above, a relatively high voltage is required to sufficiently displace the piezoelectric film, and this relatively high voltage is also applied to the pad electrodes. Therefore, in the case of ACF / ACP in which conductive particles are present in the adhesive, there is a possibility of leakage current or the like occurring. For these reasons, when the pitch between adjacent pad electrodes becomes about 50 μm or less, NCF / NCP is often used from the viewpoint of reliability. For example, Patent Document 1 discloses that when the drive contacts (pad electrodes) of a piezoelectric element are arranged in a fine pitch, mounting is performed using NCF / NCP.

[0005] Also, when manufacturing a liquid ejection head, in order to ensure the reliability of the liquid ejection head, electrical inspection, aging, screening, etc. of the piezoelectric element are carried out. For example, Patent Document 2 discloses that after forming a pressure chamber, aging and screening of the piezoelectric element are carried out. In the aging of the piezoelectric element, an electrical signal (also referred to as a drive signal) with a higher voltage and higher frequency than when actually used is applied to the piezoelectric film. Also, in the aging of the piezoelectric element, the piezoelectric element may be heated. Thereby, by polarizing the piezoelectric film or relaxing the internal stress of various thin films constituting the piezoelectric element, the temporal variation of the piezoelectric element under the conditions when actually used is reduced. In the screening of the piezoelectric element, the piezoelectric film is driven under conditions more severe than aging to exclude incompatible piezoelectric elements. When applying an electrical signal during electrical inspection or the like in the middle of the manufacturing process of the liquid ejection head, probing is performed by bringing a probe for applying an electrical signal into contact with a pad electrode connected to a lead - out wiring to apply an electrical signal to the piezoelectric element.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] For lead wiring and pad electrodes, materials with low electrical resistivity (for example, gold (Au), aluminum (Al), copper (Cu), etc.) are often used. Many of the above-mentioned materials with low electrical resistivity are relatively soft materials, and their hardness is about 20 to 30 HV in terms of Vickers hardness. For this reason, the pad electrode may be physically damaged (for example, peeled off) by probing, and irregularities with a height difference of 1 μm or more, that is, probe marks, may be formed on the pad electrode. When a flexible substrate is mounted on the pad electrode with probe marks formed, connection failures may occur due to the irregularities of the probe marks.

[0008] An object of the present disclosure is to provide a liquid ejection head with high electrical reliability.

Means for Solving the Problems

[0009] A liquid ejection head according to one aspect of the present disclosure includes a substrate in which a pressure chamber communicating with an ejection port from which droplets are ejected is formed, a diaphragm provided on one surface side of the substrate, and a piezoelectric element having a first electrode, a piezoelectric body, and a second electrode in this order on a surface of the diaphragm opposite to the substrate. The liquid ejection head further includes a first wiring having an electrical resistivity lower than that of the first electrode and electrically connected to the first electrode, and a second wiring having an electrical resistivity lower than that of the first electrode and electrically connected to the second electrode. At least one of the first wiring and the second wiring is electrically connected to a pad electrode formed in the same layer as the first electrode. The pad electrode has a pad region to which a mounting electrode for applying an electrical signal to the piezoelectric element from the outside is joined, and a connection region to which the wiring electrically connected to the pad electrode is joined.

Advantages of the Invention

[0010] According to the present disclosure, a liquid ejection head with high electrical reliability can be provided.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Embodiments for Carrying Out the Invention

[0012] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. It should be noted that the following embodiments do not limit the present disclosure, and not all combinations of the features described in the following embodiments are essential for the solution means of the present disclosure. For the same configuration, the same reference numerals will be used for description.

[0013] <<Comparative Example>> FIG. 11 is a schematic cross-sectional view showing a comparative example of an electrical inspection. FIG. 11(a) is a schematic cross-sectional view showing a comparative example of an electrical inspection using a probe 231. FIG. 11(b) is a schematic cross-sectional view showing the occurrence state of a probe mark 232 when an electrical inspection is performed. In the comparative examples shown in FIGS. 11(a) and 11(b), a pad electrode 211 having a general aluminum electrode layer is formed on the upper surface side of a substrate 200 via an insulating layer 201. The substrate 200 is formed using silicon (Si) or the like. As shown in FIG. 11(a), when probing is performed, the probe 231 is brought into contact with the pad electrode 211 and scanned in the arrow direction (+X direction in FIG. 11(a)). Here, the scanning distance of the probe 231 is referred to as the overdrive amount. The region where the probe 231 contacts is referred to as the probing region 233.

[0014] As shown in FIG. 11(b), in the probing region 233, the pad electrode 211 may be bent and deformed, and large irregularities with the residue of the bend as a protrusion, that is, probe marks 232, may be formed. When a flexible substrate (not shown) is mounted on the pad electrode 211 with probe marks 232 formed thereon, connection failures may occur due to the irregularities of the probe marks 232. Further, when a mounting electrode is formed on the pad electrode 211 by gold plating or the like in order to improve the connection reliability with the electrode of the flexible substrate, the flexible substrate is mounted on the pad electrode 211 when the mounting electrode of the pad electrode 211 comes into contact with the electrode of the flexible substrate. When the mounting electrode is formed by gold plating or the like, the mounting electrode may grow abnormally due to the probe marks 232, and irregularities may also be formed on the mounting electrode. When a flexible substrate is mounted on the pad electrode 211 using NCF / NCP, NCF or NCP is likely to enter between the mounting electrode of the pad electrode 211 and the electrode of the flexible substrate due to the irregularities formed on the mounting electrode. For this reason, the possibility of connection failures occurring may increase.

[0015] In this embodiment, a configuration capable of providing a liquid ejection head with high electrical reliability by increasing the hardness of the pad electrode will be described.

[0016] <<Embodiment>> <Flow path configuration of liquid ejection head> FIG. 1 is a schematic diagram showing the flow path configuration in the element substrate 50 of a liquid ejection head (not shown) according to the present embodiment. FIG. 1(a) is a cross-sectional view seen from the ejection port 11 side of the flow path block 10 in the element substrate 50. FIG. 1(b) is a cross-sectional view taken along the line Ib-Ib in FIG. 1(a). The element substrate 50 includes three types of substrates (a first flow path substrate 20, a second flow path substrate 100, and a third flow path substrate 40), and flow paths are formed by combining these substrates. As shown in FIG. 1(a), the flow path block 10 includes ejection ports 11 arranged along the Y direction, pressure chambers 12 prepared to communicate with each of these ejection ports 11, and supply channels 13. Each of the supply channels 13 connected to the common liquid chamber 14 supplies liquid (hereinafter also referred to as ink) to the pressure chamber 12. The arrows in FIG. 1 indicate the flow of the liquid (ink).

[0017] As shown in FIG. 1(b), the element substrate 50 in the present embodiment is configured by laminating a first flow path substrate 20, a second flow path substrate 100, and a third flow path substrate 40 in the Z direction. The first flow path substrate 20 is a substrate including an ejection port 11 for ejecting ink. The second flow path substrate 100 is a substrate on which a piezoelectric element 105 and a pressure chamber 12 are formed. The third flow path substrate 40 is a substrate that isolates the piezoelectric film 103 portion of the piezoelectric element 105 from the ink and includes a flow path for supplying ink from the common liquid chamber 14 to the pressure chamber 12. Note that the first flow path substrate 20, the second flow path substrate 100, and the third flow path substrate 40 are formed using silicon (Si) or the like.

[0018] A supply channel 13, a pressure chamber 12, and an ejection port 11 are formed corresponding to each of the individual piezoelectric elements 105. Adjacent pressure chambers 12 are separated by a partition wall and are not affected by the direct pressure of adjacent piezoelectric elements 105. Here, the piezoelectric element 105 is formed adjacent to an insulating film 101 that serves as a diaphragm.

[0019] The ink contained in the pressure chamber 12 forms a meniscus at the discharge port 11 in a stable state. When a voltage waveform is applied to the piezoelectric element 105 according to a drive signal, the piezoelectric element 105 deforms and can expand or contract the pressure chamber 12 via the insulating film 101. By combining the expansion and contraction operations, droplets (ink droplets) 60 are generated from the meniscus, and the ink droplets are discharged in the -Z direction.

[0020] The ink in the pressure chamber 12 consumed by the discharge operation is supplied from the common liquid chamber 14 by the capillary force of the discharge port 11, and the meniscus is reformed at the discharge port 11. In this embodiment, a combination of the discharge port 11, the piezoelectric element 105, and the pressure chamber 12 is referred to as a discharge element.

[0021] In this embodiment, the diameter of the discharge port 11 may be 25 μm, the thickness of the discharge port 11 may be 30 μm, and the thickness of the first flow path substrate 20 may be 100 μm. Also, the viscosity of the ink to be used may be 4 cp, and the minimum ink discharge amount from each discharge port 11 may be 3 pL.

[0022] In this embodiment, the drive frequency of each piezoelectric element 105 may be 30 kHz. Such a drive frequency can be appropriately set from the time required for the ink to be actually discharged after applying a voltage to the piezoelectric element 105 in each discharge element, and for new ink to be refilled to enable the next discharge operation.

[0023] The liquid discharge head is configured by arranging a plurality of element substrates on which a plurality of discharge elements are arranged. Each of the element substrates is generally connected to a flexible substrate 160 (see FIG. 3 described later), and further connected to an electrical wiring substrate (not shown). The electrical wiring substrate is provided with a power supply terminal for supplying power and a signal input terminal for receiving a drive signal. On the other hand, an ink supply unit (not shown) is formed with a circulation flow path (not shown) for supplying the ink having the coloring material supplied by an ink tank (not shown) to each element substrate and for recovering the ink not consumed in the recording.

[0024] Under the above configuration, each of the ejection elements arranged on the element substrate 50 uses the power supplied from the power supply terminal based on the recording data input from the signal input terminal, and ejects the ink supplied from the ink supply unit from the ejection port in the -Z direction. Note that the dimensional values of each part shown above are merely examples and may be appropriately changed according to the required specifications. Also, although an example of ejecting ink as a liquid is described, it is not limited to this, and for example, a primer may be ejected as a liquid.

[0025] <Structure of the liquid ejection head> FIG. 2 is a schematic diagram for explaining the liquid ejection head of the present embodiment. FIG. 2(a) is a plan view schematically showing the liquid ejection head. FIG. 2(b) is a cross-sectional view taken along line IIb-IIb of FIG. 2(a). In FIGS. 2(a) and 2(b), only the second flow path substrate 100 of the element substrate 50 is shown in a simplified manner in order to clearly show the arrangement of the piezoelectric elements 105, each wiring, etc., and the illustration of the ejection port 11 and the supply flow path 13 shown in FIGS. 1(a) and 1(b) is omitted.

[0026] As shown in FIGS. 2(a) and 2(b), the liquid ejection head of the present embodiment includes a second flow path substrate 100 (element substrate 50), an insulating film 101, and a plurality of piezoelectric elements 105. The liquid ejection head of the present embodiment further includes a first wiring 112, a second wiring 114, a pad electrode 115, and a mounting electrode 116. As shown in FIG. 2(b), an insulating film 101 serving as a diaphragm is formed on the upper surface side (one surface side) of the second flow path substrate 100. For the insulating film 101, a general insulator material such as a silicon oxide film, a silicon nitride film, a silicon oxynitride film, or an aluminum oxide film is used. Also, the insulating film 101 may be a laminated film in which at least two of a silicon oxide film, a silicon nitride film, a silicon oxynitride film, and an aluminum oxide film are laminated.

[0027] On the upper surface of the insulating film 101, a first electrode 102, a piezoelectric film 103, and a second electrode 104 are arranged in this order, and a piezoelectric element 105 is constituted by these first electrode 102, piezoelectric film 103, and second electrode 104. Incidentally, in the portion of the second flow path substrate 100 located on the side opposite to the piezoelectric element 105, a plurality of pressure chambers 12 are formed corresponding to the plurality of piezoelectric elements 105. On the surface of the pressure chamber 12 located on the side opposite to the piezoelectric element 105, a plurality of discharge ports 11 (not shown in FIGS. 2(a) and 2(b)) of the first flow path substrate 20 are arranged corresponding to the plurality of pressure chambers 12. Thereby, the pressure chamber 12 and the discharge port 11 communicate with each other.

[0028] The first electrode 102 is formed on the upper surface of the insulating film 101, in other words, on the surface of the insulating film 101 on the side opposite to the second flow path substrate 100. The material of the first electrode 102 may be platinum (Pt) or iridium (Ir). Also, the material of the first electrode 102 may be a platinum alloy or an iridium alloy. The first electrode 102 also serves as a film for controlling to follow the crystal orientation of the piezoelectric film 103. When the material of the piezoelectric film 103 is lead zirconate titanate, the material of the first electrode 102 is preferably either platinum or iridium, or an alloy thereof. Incidentally, the film for controlling to follow the crystal orientation of the piezoelectric film 103 is also referred to as a crystal orientation control film. Also, as an adhesion layer for obtaining the adhesion between the first electrode 102 and the insulating film 101, a thin film (not shown) such as titanium (Ti) or chromium (Cr) may be formed between the first electrode 102 and the insulating film 101.

[0029] The piezoelectric film 103 is formed on the upper surface of the first electrode 102, in other words, on the surface of the first electrode 102 on the side opposite to the insulating film 101. As the material of the piezoelectric film 103, lead zirconate titanate-based ceramics are well known. The piezoelectric film 103, which is a film-type piezoelectric body, can be formed by vacuum sputtering, sol-gel solution coating, CVD coating, etc. The thickness of the piezoelectric film 103 is determined from the applied voltage and piezoelectric characteristics necessary to obtain the desired displacement amount. For example, the thickness of the piezoelectric film 103 may be about 1 to 2 μm.

[0030] The second electrode 104 is formed on the upper surface of the piezoelectric film 103, that is to say, on the surface of the piezoelectric film 103 opposite to the first electrode 102. The material of the second electrode 104 may be platinum, may be titanium, or may be tungsten (W). Also, the material of the second electrode 104 may be a platinum alloy, may be a titanium alloy, or may be a tungsten alloy. Thus, the material of the second electrode 104 is preferably any single substance or alloy of platinum, titanium, and tungsten. Incidentally, a titanium alloy is often used as the material of the second electrode 104. Further, as an adhesion layer for obtaining the adhesion between the second electrode 104 and the piezoelectric film 103, a thin film (not shown) such as titanium or chromium may be formed between the second electrode 104 and the piezoelectric film 103.

[0031] As shown in FIG. 2(a), a plurality of piezoelectric elements 105 are arranged at high density in order to print a high-definition image. In FIG. 2(a), for the sake of easy explanation of the present embodiment, an example in which the piezoelectric elements 105 are arranged in a two-row staggered pattern in a plane is shown. The piezoelectric elements 105 may be arranged in four rows, may be arranged in eight rows, or may be a liquid ejection head arranged at an even higher density.

[0032] As shown in Fig. 2(a), the first wiring 112 electrically connected to the first electrode 102 is drawn out to the end side in the -X direction on the upper surface of the insulating film 101. Also, the second wiring 114 electrically connected to the second electrode 104 is drawn out to the end side in the -X direction on the upper surface of the insulating film 101 across the insulating layer 110. Note that the first wiring 112 and the second wiring 114 are also referred to as lead-out wirings. The first wiring 112 is a common wiring drawn out from a plurality of (for example, four) piezoelectric elements 105 (first electrodes 102). The first wiring 112 functions as a common electrode for applying a common electrical signal to the plurality of piezoelectric elements 105. The second wiring 114 is an individual wiring drawn out from each piezoelectric element 105 (second electrode 104). The second wiring 114 functions as an individual electrode for applying an electrical signal to each piezoelectric element 105. A general metal material can be used for the first wiring 112 and the second wiring 114. In order to reduce the influence of signal delay, voltage drop, etc. due to wiring resistance, a metal with a relatively low electrical resistivity is used for the first wiring 112 and the second wiring 114. For example, the material of the first wiring 112 and the second wiring 114 may be gold, may be aluminum, or may be copper. Also, the material of the first wiring 112 and the second wiring 114 may be a gold alloy, may be an aluminum alloy, or may be a copper alloy. Thus, the material of the first wiring 112 and the second wiring 114 is preferably any single substance or alloy of gold, aluminum, and copper. Also, as an adhesion layer for improving the adhesion of the first wiring 112 and the second wiring 114, a thin film (not shown) such as titanium or chromium may be formed on the lower surfaces of the first wiring 112 and the second wiring 114.

[0033] The insulating layer 110 is formed on the side portion of the piezoelectric element 105 on the -X direction side. For the insulating layer 110, common insulator materials such as a silicon oxide film, a silicon nitride film, a silicon oxynitride film, and an aluminum oxide film are used, for example. Further, the insulating layer 110 may be a laminated film in which at least two of a silicon oxide film, a silicon nitride film, a silicon oxynitride film, and an aluminum oxide film are laminated. Incidentally, for the purpose of solving problems in the manufacture of the liquid ejection head and protecting each member of the liquid ejection head, an insulating layer may be formed between the first wiring 112 and the first electrode 102, and between the second wiring 114 and the second electrode 104. In this case, the first wiring 112 and the first electrode 102 may be joined through a contact hole formed through the insulating layer between the first wiring 112 and the first electrode 102. The second wiring 114 and the second electrode 104 may be joined through a contact hole formed through the insulating layer between the second wiring 114 and the second electrode 104. Further, a protective insulating layer covering the upper surface side of the first wiring 112 or the second wiring 114 may be formed. For the insulating layer and the protective insulating layer in which the contact hole is formed through, the illustration is omitted in order to explain this embodiment in an easy-to-understand manner.

[0034] Pad electrodes 115 for applying electrical signals from the outside are electrically connected to both the first wiring 112 and the second wiring 114, respectively. Note that the pad electrode 115 electrically connected to the first wiring 112 may be referred to as the first pad electrode. The pad electrode 115 electrically connected to the second wiring 114 may be referred to as the second pad electrode. The pad electrodes 115 are arranged in a plurality and arrayed in a region different from the piezoelectric element 105 on the upper surface side of the insulating film 101, specifically, in a region along the peripheral portion on one side (-X direction side) of the second flow path substrate 100. The arrangement direction of the pad electrodes 115 is the direction along the peripheral portion on one side (-X direction side) of the second flow path substrate 100 extending in the Y direction (that is, the Y direction). In FIGS. 2(a) and 2(b), the pad electrodes 115 are arranged only on one side of the second flow path substrate 100 (insulating film 101), but are not limited thereto. For example, they may be arranged separately on both sides (-X direction side and +X direction side) of the second flow path substrate 100. Note that since the pad electrodes 115 are arranged only on one side of the second flow path substrate 100 (insulating film 101), the pad electrodes 115 are intensively arranged on one side of the second flow path substrate 100, so that the chip-type liquid ejection head (element substrate 50) can be miniaturized. Further, since the pad electrodes 115 are intensively arranged on one side of the second flow path substrate 100, the number of flexible substrates mounted on the mounting electrodes 116 can be reduced, and the man-hours for mounting the flexible substrates on the mounting electrodes 116 can be reduced. Therefore, the manufacturing cost of the liquid ejection head can be reduced.

[0035] The pad electrode 115 is formed in the same layer as the first electrode 102. Therefore, similar to the first electrode 102, the material of the pad electrode 115 is preferably any single substance or alloy of platinum and iridium. Further, similar to the first electrode 102, a thin film (not shown) such as titanium or chromium may be formed between the pad electrode 115 and the insulating film 101 as an adhesion layer for obtaining adhesion between the pad electrode 115 and the insulating film 101. Note that forming in the same layer as the first electrode 102 means being formed from the layer that is the material of the first electrode 102, specifically, the first electrode layer 102E (see FIGS. 4(b) and 4(c)) described later.

[0036] Also, the pad electrode 115 is formed to extend longer in the X direction than in the Y direction. The pad electrode 115 has a pad region 150 and a connection region 151 arranged in the X direction. The pad region 150 is formed on the -X direction side of the pad electrode 115. A mounting electrode 116 for applying an electrical signal to the piezoelectric element 105 from the outside is joined to the upper surface of the pad region 150. The connection region 151 is formed on the +X direction side of the pad electrode 115. An end portion on the -X direction side of the first wiring 112 or the second wiring 114 is joined to the upper surface of the connection region 151.

[0037] It is preferable that the ratio of the length of the connection region 151 to the length of the pad electrode 115 in the direction (X direction) intersecting the arrangement direction of the pad electrodes 115 is 0.2 or less (20% or less). Thereby, since the pad region 150 becomes relatively long, it becomes easier to secure a region (probing region) where a probe can be brought into contact with the pad electrode 115.

[0038] Also, it is preferable that the ratio of the length of the mounting electrode 116 to the length of the pad electrode 115 in the direction (X direction) intersecting the arrangement direction of the pad electrodes 115 is 0.5 or more (50% or more). Thereby, since the area of the mounting electrode 116 can be sufficiently secured, even if the arrangement pitch of the pad electrodes 115 is narrow, electrical connection to the mounting electrode 116 (mounting of the flexible substrate) can be surely performed.

[0039] The mounting electrode 116 is formed to extend longer in the X direction than in the Y direction on the upper surface of the pad region 150. A generally used metal material can be used for the mounting electrode 116. For example, the material of the mounting electrode 116 may be gold, may be aluminum, or may be copper. Also, the material of the mounting electrode 116 may be a gold alloy, may be an aluminum alloy, or may be a copper alloy. Thus, the material of the mounting electrode 116 is preferably any single substance or alloy of gold, aluminum, and copper. Further, as an adhesion layer for improving the adhesion between the mounting electrode 116 and the pad region 150, a thin film (not shown) such as titanium or chromium may be formed between the mounting electrode 116 and the pad region 150. Also, a flexible substrate is mounted on the mounting electrode 116. The material of the mounting electrode 116 is selected in consideration of the electrode material of the flexible substrate mounted on the mounting electrode 116, the mounting method of the flexible substrate, etc. When using NCF / NCP as the mounting method of the flexible substrate, it is preferable to form the mounting electrode 116 by gold plating or the like and join it to the pad region 150.

[0040] In the liquid ejection head, the piezoelectric elements 105 are driven by individual wirings (second wirings 114) that individually supply signals to the individual piezoelectric elements 105 and a common wiring (first wiring 112) that supplies a common signal to the plurality of piezoelectric elements 105. Also, when the number of piezoelectric elements 105 is large, one common wiring is arranged for some of the piezoelectric elements 105 due to problems such as the area for arranging each lead wiring and wiring resistance. For example, as shown in Fig. 2(a), when the piezoelectric elements 105 are arranged in two rows, one common wiring is arranged for four piezoelectric elements 105. Also, for example, when the piezoelectric elements 105 are arranged in four rows, one common wiring may be arranged for eight piezoelectric elements 105. When the piezoelectric elements 105 are arranged in eight rows, one common wiring may be arranged for sixteen piezoelectric elements 105. For this reason, the number of the first wiring 112 and the second wiring 114 is larger than the number of piezoelectric elements 105, and the number of pad electrodes 115 corresponding to the first wiring 112 and the second wiring 114 also increases. As an example, a case where the piezoelectric elements 105 are arranged at 600 npi and one common wiring is arranged for eight piezoelectric elements 105 will be described. In this case, when the pad electrodes 115 connected to the common wiring (first wiring 112) and the pad electrodes 115 connected to the individual wiring (second wiring 114) are arranged in a row, the arrangement pitch of the pad electrodes 115 is about 50 μm or 50 μm or less. When the arrangement pitch of the pad electrodes 115 becomes about 50 μm or less, as described above, NCF / NCP is often used as the mounting method for the flexible substrate.

[0041] In the present embodiment, before forming the mounting electrode 116, an electrical inspection of the piezoelectric element 105 is performed. In the process of performing the electrical inspection, a probe for applying an electrical signal to the pad region 150 of the pad electrode 115 is brought into contact to perform electrical inspection, aging, screening, etc. of the piezoelectric element 105. After the process of performing the electrical inspection is carried out, the mounting electrode 116 is formed on the pad region 150 of the pad electrode 115.

[0042] As described above, in the process of performing an electrical inspection, a probe is brought into contact with a pad region 150 where the first wiring 112 and the second wiring 114 do not exist. The materials of the first wiring 112 and the second wiring 114 (such as gold, aluminum, copper, etc.) are metal materials with relatively low electrical resistivity and softness. For example, the electrical resistivity of gold is 2.44×10 -8 Ω·m, and the hardness of gold is about 22 HV in terms of Vickers hardness. The electrical resistivity of aluminum is 2.65×10 -8 Ω·m, and the hardness of aluminum is about 25 HV in terms of Vickers hardness. The electrical resistivity of copper is 1.68×10 -8 Ω·m, and the hardness of copper is about 38 HV in terms of Vickers hardness.

[0043] On the other hand, the pad electrode 115 is formed in the same layer as the first electrode 102. Therefore, the material of the pad electrode 115 (such as platinum, iridium, etc.) is a hard material with relatively high electrical resistivity and a Vickers hardness of 45 HV or more. For example, the electrical resistivity of platinum is 1.06×10 -7 Ω·m, and the hardness of platinum is about 50 HV in terms of Vickers hardness. The electrical resistivity of iridium is 5.20×10 -8 Ω·m, and the hardness of iridium is about 180 HV in terms of Vickers hardness.

[0044] Tungsten, which is generally used as the material of the probe, is a harder metal than the material of the pad electrode 115 (such as platinum, iridium, etc.). The hardness of tungsten is about 350 HV in terms of Vickers hardness. When probing, since the probe contacts the surface of the pad region 150 in the pad electrode 115 so as to slide, the pad electrode 115 does not require the same degree of hardness as the probe. If the pad electrode 115 is a flat thin film having a hardness of about 45 HV or more in terms of Vickers hardness, physical damage to the pad electrode 115 due to probing, that is, probe marks, can be suppressed.

[0045] This makes it possible to perform electrical inspection, aging, screening, etc. of the piezoelectric element 105 without generating probe marks on the pad electrode 115. Then, after the step of performing the electrical inspection, by forming the mounting electrode 116 for connection to the outside in the pad region 150 of the flat pad electrode 115 without probe marks, it is possible to form the mounting electrode 116 with a flat and uniform surface.

[0046] FIG. 3 is a schematic diagram showing a state in which the flexible substrate 160 is mounted on the mounting electrode 116. In the example shown in FIG. 3, NCF / NCP is used as the mounting method of the flexible substrate 160. The flexible substrate 160 is mounted on the mounting electrode 116 using the non-conductive adhesive 165 which is NCF or NCP. When mounting the flexible substrate 160 on the mounting electrode 116, since the electrode 161 of the flexible substrate 160 can be brought into contact with the flat and uniform surface of the mounting electrode 116, the occurrence of connection failure when mounting the flexible substrate 160 can be suppressed.

[0047] <Method for manufacturing a liquid ejection head> Next, the method for manufacturing a liquid ejection head will be described with reference to FIGS. 4 to 6. FIGS. 4 to 6 are process cross-sectional views for explaining the manufacturing process of the liquid ejection head.

[0048] As shown in FIG. 4(a), a silicon single crystal substrate 100E that is the material of the second flow path substrate 100 is prepared. Hereinafter, the substrate 100E that is the material of the second flow path substrate 100 will be simply referred to as the substrate 100E. On the upper surface (one surface) of this substrate 100E, a silicon thermal oxide film is formed by a wet oxidation method using oxygen and hydrogen gas to form the insulating film 101.

[0049] Also, the layer that is the material of the first electrode 102 and the pad electrode 115 is referred to as the first electrode layer 102E. The layer that is the material of the piezoelectric film 103 is referred to as the piezoelectric film layer 103E. The layer that is the material of the second electrode 104 is referred to as the second electrode layer 104E. The film that is the material of the insulating layer 110 is referred to as the material film 110E. The layer that is the material of the first wiring 112 and the second wiring 114 is referred to as the wiring layer 114E.

[0050] Subsequently, as shown in FIG. 4(b), a first electrode layer 102E, a piezoelectric film layer 103E, and a second electrode layer 104E are sequentially stacked in the +Z direction on the insulating film 101. In the step of forming the first electrode layer 102E, the first electrode layer 102E is formed by sputtering on the insulating film 101. When the material of the piezoelectric film layer 103E is lead zirconate titanate, the material of the first electrode layer 102E that functions as a crystal orientation control film is preferably either platinum or iridium, or an alloy thereof. As an adhesion layer for obtaining the adhesion between the first electrode layer 102E and the insulating film 101, a thin film (not shown) such as titanium or chromium may be formed between the first electrode layer 102E and the insulating film 101. In the step of forming the piezoelectric film layer 103E, the piezoelectric film layer 103E is formed by a sol-gel method or the like on the first electrode layer 102E, and the piezoelectric film layer 103E is fired so as to have a desired crystal orientation. In the step of forming the second electrode layer 104E, the second electrode layer 104E is formed by sputtering on the piezoelectric film layer 103E. As the material of the second electrode layer 104E, a general metal material can be used. Incidentally, the material of the second electrode layer 104E is preferably either platinum, titanium, or tungsten, or an alloy thereof.

[0051] Subsequently, as shown in FIG. 4(c), the second electrode 104 and the piezoelectric film 103 are formed by patterning the second electrode layer 104E and the piezoelectric film layer 103E. In the step of patterning the second electrode layer 104E and the piezoelectric film layer 103E, a resist pattern (not shown) is formed on the second electrode layer 104E so as to have a desired pattern by a photolithography method. After forming the resist pattern, the portions of the second electrode layer 104E and the piezoelectric film layer 103E other than the portions that become the second electrode 104 and the piezoelectric film 103 are removed by etching.

[0052] Subsequently, as shown in FIG. 4(d), by patterning the first electrode layer 102E, the first electrode 102 and the pad electrode 115 are formed. In the step of patterning the first electrode layer 102E, a resist pattern (not shown) is formed on the first electrode layer 102E so as to have a desired pattern by photolithography again. After forming the resist pattern, the portion of the first electrode layer 102E except for the portions that will become the first electrode 102 and the pad electrode 115 is removed by etching. By this etching, the piezoelectric element 105 composed of the first electrode 102, the piezoelectric film 103, and the second electrode 104 is formed, and the pad electrode 115 is formed.

[0053] Subsequently, as shown in FIG. 5(a), a material film 110E is formed on the insulating film 101, the piezoelectric element 105, and the pad electrode 115. In the step of forming the material film 110E, the material film 110E is formed by CVD (Chemical Vapor Deposition) or the like. As the material film 110E, a silicon oxide film, a silicon nitride film, a silicon oxynitride film, an aluminum oxide film, or the like is used.

[0054] Subsequently, as shown in FIG. 5(b), by patterning the material film 110E, the insulating layer 110 is formed. In the step of patterning the material film 110E, a resist pattern (not shown) is formed on the material film 110E so as to have a desired pattern by photolithography. After forming the resist pattern, the portion of the material film 110E except for the portion that will become the insulating layer 110 is removed by etching.

[0055] Subsequently, as shown in FIG. 5(c), a wiring layer 114E is formed on the insulating film 101, the piezoelectric element 105, the pad electrode 115, and the insulating layer 110. In the step of forming the wiring layer 114E, the wiring layer 114E is formed by sputtering. The material of the wiring layer 114E is preferably any one of gold, aluminum, and copper, or an alloy thereof.

[0056] Subsequently, as shown in FIG. 5(d), the wiring layer 114E is patterned to form the first wiring 112 and the second wiring 114. In the process of patterning the wiring layer 114E, a resist pattern (not shown) is formed on the wiring layer 114E by photolithography so as to have a desired pattern. After the resist pattern is formed, the portion of the wiring layer 114E except for the portions that will become the first wiring 112 and the second wiring 114 is removed by etching. When performing the etching, the portion of the wiring layer 114E that overlaps with the pad region 150 of the pad electrode 115 is removed, and the end of the first wiring 112 or the second wiring 114 is joined to the connection region 151 of the pad electrode 115.

[0057] Subsequently, as shown in FIG. 6(a), an electrical inspection is performed. In the process of performing the electrical inspection, the probe 231 is brought into contact with the pad region 150 of the pad electrode 115 and scanned in the arrow direction (+X direction in FIG. 6(a)). Thereby, the probe 231 and the pad electrode 115 are electrically connected. Here, it is assumed that the probing region 233 is set within the pad region 150 of the pad electrode 115. The pad electrode 115 is formed in the same layer as the first electrode 102. Therefore, the material of the pad electrode 115 is a hard metal material having a Vickers hardness of 45 HV or more, such as platinum or iridium. For this reason, the pad electrode 115 is not scratched even in the probing region 233, and no probe mark 232 as shown in FIG. 11(b) described above is generated. In this state, by applying an electrical signal to the piezoelectric element 105 via the probe 231, electrical inspection, aging, screening, etc. of the piezoelectric element 105 are performed.

[0058] Subsequently, as shown in FIG. 6(b), a mounting electrode 116 is formed in the pad region 150 of the pad electrode 115. As the material of the mounting electrode 116, a generally used metal material can be used. As described above, when using NCF / NCP as the mounting method for the flexible substrate, it is preferable to form the mounting electrode 116 by gold plating or the like and bond it to the pad region 150. In the process of forming the mounting electrode 116, a laminated film of a titanium-tungsten alloy thin film and a gold thin film formed by sputtering is used as a seed layer, a resist pattern is formed in an unnecessary region, and gold plating is performed. After the gold plating, the resist and the seed layer in the unnecessary region are removed to form the mounting electrode 116. Since the seed layer is formed and gold plating is performed on the pad region 150 of the pad electrode 115 without probe marks and flat, a flat and uniform mounting electrode 116 can be formed.

[0059] Although detailed illustration is omitted, after forming the mounting electrode 116, processing for forming a pressure chamber is performed on the substrate 100E. After the process of forming the pressure chamber, a substrate serving as a material of the third flow path substrate 40 is bonded to the upper surface side of the substrate 100E, and a substrate serving as a material of the first flow path substrate 20 is bonded to the lower surface side of the substrate 100E. Thereby, a composite substrate in which a plurality of chip-type liquid ejection heads (element substrates 50) are formed is formed. After the process of bonding the substrates, the plurality of element substrates 50 formed on the composite substrate are divided. After the process of dividing the plurality of element substrates 50, a flexible substrate is mounted on the mounting electrode 116 using NCF / NCP. In this way, after forming the mounting electrode 116, through processes such as the process of forming a pressure chamber, the process of bonding the substrates, the process of dividing the plurality of element substrates 50, and the process of mounting the flexible substrate, the liquid ejection head is completed.

[0060] In this embodiment, the flexible substrate is mounted on the flat and uniform mounting electrode 116 using NCF / NCP. Therefore, the occurrence of connection failures during the mounting of the flexible substrate can be suppressed, and a liquid ejection head with high electrical reliability can be manufactured with good yield. Further, the pad electrode 115 has a pad region 150 to which the mounting electrode 116 is joined and a connection region 151 to which the first wiring 112 or the second wiring 114 is joined. Thereby, even when the piezoelectric elements 105 are arranged at high density, it is not necessary to separately provide pad electrodes for electrical inspection in the process of performing electrical inspection, and the pad region 150 of the pad electrode 115 can be used also as the pad electrode for electrical inspection.

[0061] As described above, according to the liquid ejection head and the method of manufacturing the liquid ejection head of this embodiment, a liquid ejection head with high electrical reliability can be provided. That is, in this embodiment, the pad electrode 115 is formed in the same layer as the first electrode 102. Therefore, as the material of the pad electrode 115, a material with a relatively high electrical resistivity and hardness can be used. Thereby, it becomes possible to perform electrical inspection, aging, screening, etc. of the piezoelectric element 105 without generating probe marks on the pad electrode 115. Then, after the process of performing electrical inspection, by forming the mounting electrode 116 for connection to the outside in the pad region 150 of the flat pad electrode 115 without probe marks, it is possible to form a flat and uniform mounting electrode 116. When mounting the flexible substrate 160 on the mounting electrode 116, the electrode 161 of the flexible substrate 160 can be brought into contact with the flat and uniform mounting electrode 116. For this reason, it becomes difficult for the non-conductive adhesive 165 to enter between the mounting electrode 116 and the electrode 161 of the flexible substrate 160, and the occurrence of connection failures during the mounting of the flexible substrate 160 can be suppressed. In this way, a liquid ejection head with high electrical reliability can be provided.

[0062] In the foregoing embodiments, NCF / NCP is used as the mounting method for the flexible substrate 160, but the present invention is not limited thereto. As the mounting method for the flexible substrate 160, ACF / ACP may be used. A mounting method using a wire bonder may also be used.

[0063] In the foregoing embodiments, the first wiring 112 is a common wiring drawn from a plurality of piezoelectric elements 105, and the second wiring 114 is an individual wiring drawn from each piezoelectric element 105, but the present invention is not limited thereto. The first wiring 112 may be an individual wiring drawn from each piezoelectric element 105, and the second wiring 114 may be a common wiring drawn from a plurality of piezoelectric elements 105.

[0064] In the foregoing embodiments, pad electrodes 115 formed in the same layer as the first electrode 102 are electrically connected to both the first wiring 112 and the second wiring 114, respectively, but the present invention is not limited thereto. A pad electrode 115 formed in the same layer as the first electrode 102 may be electrically connected to one of the first wiring 112 and the second wiring 114. For example, a pad electrode 115 formed in the same layer as the first electrode 102 may be electrically connected only to the second wiring 114. In this case, a mounting electrode may be joined to a pad region provided at the -X direction side end of the first wiring 112. Also in this case, ACF / ACP may be used as the mounting method for the flexible substrate.

[0065] <<Example>> Next, specific examples regarding the liquid ejection head will be described with reference to the drawings.

[0066] <Example 1> FIG. 7 is a plan view of Example 1 corresponding to the above-described embodiment. FIG. 7(a) is an overall plan view of the liquid ejection head of Example 1. FIG. 7(b) is an enlarged view of the pad electrode 115 of Example 1. Since the individual members in Example 1 have the same configuration as those in the above-described embodiment, the same reference numerals as those of the respective members in the above-described embodiment will be given and described.

[0067] In Example 1, as shown in FIG. 7(a), the individual piezoelectric elements 105 are arranged in a staggered pattern of four rows with a density of 600 npi in the Y direction. The array pitch p1 of the piezoelectric elements 105 in the Y direction is approximately 42 μm. The size of the piezoelectric element 105 in the X direction is approximately 700 μm, and the size of the piezoelectric element 105 in the Y direction is approximately 50 μm. For the first wiring 112 which is a common wiring, one first wiring 112 is arranged for eight piezoelectric elements 105 in view of the relationship between the wiring layout and the wiring resistance. As shown in FIG. 7(b), the pad electrodes 115 are arranged only on one side (-X direction side) of the second flow path substrate 100 (not shown in FIG. 7(b)). The array pitch p2 of the pad electrodes 115 in the Y direction is approximately 38 μm.

[0068] Also, the liquid ejection head of Example 1 is manufactured in the same manner as the manufacturing method of the liquid ejection head of the above-described embodiment. In the step of forming the insulating film 101 (see FIG. 4(a)), the film thickness of the silicon thermal oxide film is set to 500 nm.

[0069] In the step of forming the first electrode layer 102E (see FIG. 4(b)), the material of the first electrode layer 102E (that is, the first electrode 102 and the pad electrode 115) is platinum, and the thickness of the first electrode layer 102E is set to 100 nm. Further, as an adhesion layer for obtaining the adhesion between the first electrode layer 102E and the insulating film 101, a titanium thin film (not shown) with a thickness of 10 nm is formed by a sputtering method. In the step of forming the piezoelectric film layer 103E (see FIG. 4(b)), the material of the piezoelectric film layer 103E (that is, the piezoelectric film 103) is lead zirconate titanate, and the thickness of the piezoelectric film layer 103E is set to 2 μm. In the step of forming the second electrode layer 104E (see FIG. 4(b)), the material of the second electrode layer 104E (that is, the second electrode 104) is an alloy of titanium and tungsten, and the thickness of the second electrode layer 104E is set to 100 μm.

[0070] In the step of forming the material film 110E (see Fig. 5(a)), a silicon oxide film is used as the material film 110E, and the thickness of the material film 110E (i.e., the insulating layer 110) is 400 nm. In the step of forming the wiring layer 114E (see Fig. 5(c)), the material of the wiring layer 114E (i.e., the first wiring 112 and the second wiring 114) is an aluminum alloy, and the thickness of the wiring layer 114E is 600 nm.

[0071] Thereby, in the step of performing the electrical inspection (see Fig. 6(a)), the electrical inspection can be carried out without the pad electrode 115 being peeled off. In the step of forming the mounting electrode 116 (see Fig. 6(b)), the mounting electrode 116 is formed by gold plating or the like, and the thickness of the mounting electrode 116 is 5 μm. At this time, since a seed layer is formed on the pad region 150 of the flat pad electrode 115 without probe marks and gold plating is performed, a flat and uniform mounting electrode 116 can be formed.

[0072] Then, in the step of mounting the flexible substrate, the flexible substrate can be mounted using NCF / NCP on the flat and uniform mounting electrode 116. Therefore, the occurrence of connection failure when mounting the flexible substrate can be suppressed, and a liquid ejection head with high electrical reliability can be manufactured with a good yield.

[0073] As described above, according to the first embodiment, a liquid ejection head with high electrical reliability can be provided.

[0074] <Example 2> Fig. 8 is a plan view of Example 2 corresponding to the above-described embodiment. Since the individual members in Example 2 have the same configuration as those in the first embodiment described above, only the differences from the first embodiment will be described.

[0075] In Example 2, as shown in FIG. 8, the individual piezoelectric elements 105 are arranged in a staggered pattern of 8 rows with a density of 1200 npi in the Y direction. The array pitch of the piezoelectric elements 105 in the Y direction is approximately 21 μm. The pad electrodes 115 are arranged separately on both sides (-X direction side and +X direction side) of the second flow path substrate 100 (not shown in FIG. 8). The array pitch of the pad electrodes 115 in the Y direction on each side of both sides is approximately 38 μm as in Example 1.

[0076] According to Example 2, similar to Example 1, a liquid ejection head with high electrical reliability can be provided.

[0077] <Example 3> FIG. 9 is a plan view showing the pad electrode 115 of Example 3 corresponding to the above-described embodiment. FIG. 9(a) is a plan view showing the pad region 150 and the connection region 151 of the pad electrode 115 of Example 3. FIG. 9(b) is a plan view showing a state in which the second wiring 114 (or the first wiring 112) is joined to the connection region 151 of the pad electrode 115 of Example 3. FIG. 9(c) is a plan view showing a state in which the mounting electrode 116 is joined to the pad region 150 of the pad electrode 115 of Example 3. Since the individual members in Example 3 have the same configuration as in Example 1 described above, only the parts different from Example 1 will be described.

[0078] In Example 3, as shown in FIG. 9(a), the pad region 150 is a region surrounded by a broken line on the central side of the pad electrode 115. The connection region 151 is a region surrounding the periphery of the pad region 150 on the outer peripheral side of the pad electrode 115. Then, as shown in FIG. 9(b), the end side of the second wiring 114 (or the first wiring 112) is formed so as to surround the periphery of the pad region 150 in the connection region 151 of the pad electrode 115. In the process of forming the first wiring 112 and the second wiring 114 (see FIG. 5(d)), when etching is performed, the portion of the wiring layer 114E that overlaps the central pad region 150 in the pad electrode 115 is removed.

[0079] Also, in the process of performing an electrical inspection (refer to FIG. 6(a)), a probe is brought into contact with a pad region 150 surrounded by the second wiring 114 (or the first wiring 112) and scanned in the X direction. Even in this case, as in the first embodiment, the pad electrode 115 is not peeled off and the electrical inspection can be carried out. After the process of performing the electrical inspection, as shown in FIG. 9(c), a mounting electrode 116 is formed in the pad region 150 surrounded by the second wiring 114 (or the first wiring 112). Even in this case, as in the first embodiment, a flat and uniform mounting electrode 116 can be formed.

[0080] According to the third embodiment, as in the first embodiment, a liquid discharge head with high electrical reliability can be provided.

[0081] Also, according to the third embodiment, the second wiring 114 (or the first wiring 112) is formed so as to surround the periphery of the pad region 150. Therefore, even if a slight alignment deviation occurs, it becomes possible to electrically connect the pad electrode 115 and the second wiring 114 (or the first wiring 112). Further, in order to increase the connection area with the electrode of the flexible substrate without changing the connection pitch, the pad electrode 115 may be formed elongated in the X direction. In such a case, since the second wiring 114 (or the first wiring 112) having a lower electrical resistivity than the pad electrode 115 is formed so as to surround the periphery of the pad region 150, there is also an effect of lowering the electrical resistance of the pad electrode 115 when performing an electrical inspection.

[0082] <Example 4> FIG. 10 is a plan view showing pad electrodes 115a and 115b of Example 4 corresponding to the above-described embodiment. Since the individual members in Example 4 have the same configuration as those in the first embodiment described above, only the parts different from the first embodiment will be described.

[0083] In Example 4, as shown in FIG. 10, two rows of pad electrodes 115a and 115b arranged in a staggered pattern in the X direction are arranged in a plurality in the Y direction. The two rows of pad electrodes 115a and 115b are formed in the same manner as the pad electrode 115 of the above-described embodiment. - A mounting electrode 116a is joined to a pad region 150a of the pad electrode 115a located on the -X direction side. - A first wiring 112 or a second wiring 114 is joined to a connection region 151a of the pad electrode 115a located on the -X direction side. + A mounting electrode 116b is joined to a pad region 150b of the pad electrode 115b located on the +X direction side. + A first wiring 112 or a second wiring 114 is joined to a connection region 151b of the pad electrode 115b located on the +X direction side. As a result, two rows of mounting electrodes 116a and 116b arranged in a staggered pattern in the X direction are arranged in a plurality in the Y direction. Also, the two rows of mounting electrodes 116a and 116b are formed in the same manner as the mounting electrode 116 of the above-described embodiment.

[0084] According to Example 4, similarly to Example 1, a liquid ejection head with high electrical reliability can be provided.

[0085] Further, according to Example 4, by arranging the pad electrodes 115a and 115b in a staggered pattern, the pad electrodes 115a and 115b can be arranged at a higher density in the Y direction without changing the size of the pad electrodes 115a and 115b. When arranging the pad electrodes 115a and 115b in a staggered pattern, it is necessary to form bumps on the wiring of the flexible substrate corresponding to the arrangement of the mounting electrodes 116a and 116b. Also, since the flexible substrate has low rigidity, there is a possibility of connection failure. For this reason, instead of the flexible substrate, a high-rigidity silicon substrate may be used, or an interposer substrate having wiring formed on a glass substrate may be used.

[0086] <<Other Embodiments>> The disclosure of this embodiment includes configurations typified by the following liquid ejection head examples and liquid ejection head manufacturing method examples.

[0087] <Configuration 1> A substrate in which a pressure chamber communicating with a discharge port for discharging droplets is formed, A diaphragm provided on one surface side of the substrate, A piezoelectric element having a first electrode, a piezoelectric body, and a second electrode in this order on the surface of the diaphragm opposite to the substrate, A first wiring having an electrical resistivity lower than that of the first electrode and electrically connected to the first electrode, A second wiring having an electrical resistivity lower than that of the first electrode and electrically connected to the second electrode, Comprising, A pad electrode formed in the same layer as the first electrode is electrically connected to at least one of the first wiring and the second wiring, The pad electrode, A pad region to which a mounting electrode for applying an electrical signal to the piezoelectric element from the outside is joined, A connection region to which the wiring electrically connected to the pad electrode is joined, A liquid discharge head characterized by having.

[0088] <Configuration 2> A substrate in which a pressure chamber communicating with a discharge port for discharging droplets is formed, A diaphragm provided on one surface side of the substrate, A piezoelectric element having a first electrode, a piezoelectric body, and a second electrode in this order on the surface of the diaphragm opposite to the substrate, A first wiring having a hardness lower than that of the first electrode and electrically connected to the first electrode, A second wiring having a hardness lower than that of the first electrode and electrically connected to the second electrode, Comprising, A pad electrode formed in the same layer as the first electrode is electrically connected to at least one of the first wiring and the second wiring, The pad electrode, A pad region to which a mounting electrode for applying an electrical signal to the piezoelectric element from the outside is joined, A connection region where the wiring electrically connected to the pad electrode is joined, A liquid ejection head, characterized by having .

[0089] <Configuration 3> The liquid ejection head according to Configuration 1 or 2, wherein the pad electrode is formed of any one of platinum and iridium, or an alloy thereof.

[0090] <Configuration 4> The liquid ejection head according to any one of Configurations 1 to 3, wherein the hardness of the pad electrode is 45 HV or more in terms of Vickers hardness.

[0091] <Configuration 5> The liquid ejection head according to any one of Configurations 1 to 4, wherein the wiring electrically connected to the pad electrode is formed of any one of gold, aluminum, and copper, or an alloy thereof.

[0092] <Configuration 6> The liquid ejection head according to any one of Configurations 1 to 5, comprising a plurality of the pad electrodes, the plurality of the pad electrodes including a first pad electrode electrically connected to the first wiring and a second pad electrode electrically connected to the second wiring.

[0093] <Configuration 7> The plurality of the pad electrodes are arranged side by side, The liquid ejection head according to any one of Configurations 1 to 6, wherein a ratio of a length of the connection region to a length of the pad electrode in a direction intersecting with an arrangement direction of the pad electrodes is 0.2 or less.

[0094] <Configuration 8> The plurality of the pad electrodes are arranged side by side, The liquid ejection head according to any one of Configurations 1 to 7, wherein a ratio of a length of the mounting electrode to a length of the pad electrode in a direction intersecting with an arrangement direction of the pad electrodes is 0.5 or more.

[0095] <Configuration 9> A plurality of the pad electrodes are arranged side by side, The liquid ejection head according to any one of Configurations 1 to 8, wherein an array pitch of the plurality of pad electrodes is 50 μm or less.

[0096] <Configuration 10> The liquid ejection head according to any one of Configurations 1 to 9, wherein the plurality of pad electrodes are arranged side by side along a peripheral portion on one side of the substrate.

[0097] <Configuration 11> Comprising a plurality of the piezoelectric elements, The substrate has a plurality of the discharge ports and a plurality of the pressure chambers respectively corresponding to the plurality of the piezoelectric elements, The liquid ejection head according to any one of Configurations 1 to 10, wherein the first wiring is a common wiring common to the plurality of piezoelectric elements, and the second wiring is an individual wiring individually used for the piezoelectric elements.

[0098] <Configuration 12> The liquid ejection head according to any one of Configurations 1 to 11, wherein the mounting electrode is formed in a layer different from the wiring electrically connected to the pad electrode.

[0099] <Configuration 13> The liquid ejection head according to any one of Configurations 1 to 12, wherein the mounting electrode is formed of any single substance or alloy of gold, aluminum, and copper.

[0100] <Configuration 14> The liquid ejection head according to any one of Configurations 1 to 13, wherein a flexible substrate is electrically connected to the mounting electrode of the substrate.

[0101] <Configuration 15> The liquid ejection head according to Configuration 14, wherein the flexible substrate is joined using a non-conductive film or a non-conductive paste.

[0102] <Configuration 16> A substrate in which a pressure chamber communicating with a discharge port for discharging droplets is formed, a diaphragm provided on one surface side of the substrate, a piezoelectric element having a first electrode, a piezoelectric body, and a second electrode in this order on the surface of the diaphragm opposite to the substrate, a first wiring having an electrical resistivity lower than that of the first electrode and electrically connected to the first electrode, a second wiring having an electrical resistivity lower than that of the first electrode and electrically connected to the second electrode, and comprising, A method for manufacturing a liquid discharge head in which a pad electrode formed in the same layer as the first electrode is electrically connected to at least one of the first wiring and the second wiring, a step of forming a first layer on the diaphragm, a step of forming the first electrode and the pad electrode by patterning the first layer, a step of forming a second layer on top of the pad electrode, a step of forming the first wiring or the second wiring electrically connected to the pad electrode by patterning the second layer, and having, In the step of patterning the second layer, a portion of the second layer that overlaps with the pad region of the pad electrode to which a mounting electrode for applying an electrical signal to the piezoelectric element from the outside is joined is removed, and the first wiring or the second wiring electrically connected to the pad electrode is joined to a connection region of the pad electrode different from the pad region. A method for manufacturing a liquid discharge head.

[0103] <Configuration 17> A substrate in which a pressure chamber communicating with a discharge port for discharging droplets is formed, a diaphragm provided on one surface side of the substrate, a piezoelectric element having a first electrode, a piezoelectric body, and a second electrode in this order on the surface of the diaphragm opposite to the substrate, A first wiring having a hardness lower than that of the first electrode and electrically connected to the first electrode, A second wiring having a hardness lower than that of the first electrode and electrically connected to the second electrode, and A method for manufacturing a liquid ejection head in which a pad electrode formed in the same layer as the first electrode is electrically connected to at least one of the first wiring and the second wiring, including a step of forming a first layer on the diaphragm, a step of forming the first electrode and the pad electrode by patterning the first layer, a step of forming a second layer on top of the pad electrode, a step of forming the first wiring or the second wiring electrically connected to the pad electrode by patterning the second layer, and In the step of patterning the second layer, a portion of the second layer that overlaps with the pad region of the pad electrode to which a mounting electrode for applying an electrical signal to the piezoelectric element from the outside is joined is removed, and the first wiring or the second wiring electrically connected to the pad electrode is joined to a connection region different from the pad region of the pad electrode. A method for manufacturing a liquid ejection head.

[0104] <Configuration 18> After the step of forming the first wiring or the second wiring electrically connected to the pad electrode, a step of performing an electrical inspection by bringing a probe into contact with the pad region, After the step of performing the electrical inspection, a step of joining the mounting electrode to the pad region, The method for manufacturing a liquid ejection head according to Configuration 16 or 17, further comprising:

[0105] <Configuration 19> The method for manufacturing a liquid ejection head according to Configuration 18, further comprising a step of mounting a flexible substrate on the mounting electrode joined to the pad region using a non-conductive film or a non-conductive paste.

[0106] <Configuration 20> A method for manufacturing a liquid ejection head according to any one of Claims 16 to 19, comprising a plurality of said pad electrodes, the plurality of said pad electrodes including a first pad electrode electrically connected to said first wiring and a second pad electrode electrically connected to said second wiring.

Explanation of Reference Numerals

[0107] 100 Second flow path substrate 101 Insulating film 102 First electrode 103 Piezoelectric film 104 Second electrode 105 Piezoelectric element 112 First wiring 114 Second wiring 115 Pad electrode 116 Mounting electrode 150 Pad region 151 Connection region

Claims

1. A substrate in which a pressure chamber communicating with a discharge port from which droplets are discharged is formed; A diaphragm provided on one surface side of the substrate; A piezoelectric element having a first electrode, a piezoelectric body, and a second electrode in this order on the surface of the diaphragm opposite to the substrate; A first wiring having an electrical resistivity lower than that of the first electrode and electrically connected to the first electrode; A second wiring having an electrical resistivity lower than that of the first electrode and electrically connected to the second electrode; Comprising; At least one of the first wiring and the second wiring is electrically connected to a pad electrode formed in the same layer as the first electrode, The pad electrode, A pad region to which a mounting electrode for applying an electrical signal to the piezoelectric element from the outside is joined; A connection region to which the wiring electrically connected to the pad electrode is joined; A liquid discharge head, characterized by having.

2. A substrate in which a pressure chamber communicating with a discharge port from which droplets are discharged is formed; A diaphragm provided on one surface side of the substrate; A piezoelectric element having a first electrode, a piezoelectric body, and a second electrode in this order on the surface of the diaphragm opposite to the substrate; A first wiring having a hardness lower than that of the first electrode and electrically connected to the first electrode; A second wiring having a hardness lower than that of the first electrode and electrically connected to the second electrode; Comprising; At least one of the first wiring and the second wiring is electrically connected to a pad electrode formed in the same layer as the first electrode, The pad electrode, A pad region to which a mounting electrode for applying an electrical signal to the piezoelectric element from the outside is joined; A connection region to which the wiring electrically connected to the pad electrode is joined; A liquid discharge head, characterized by having.

3. The liquid discharge head according to claim 1 or 2, wherein the pad electrode is formed of any single substance or alloy of platinum and iridium.

4. The liquid discharge head according to claim 1 or 2, wherein the hardness of the pad electrode is 45 HV or more in terms of Vickers hardness.

5. The liquid discharge head according to claim 1 or 2, wherein the wiring electrically connected to the pad electrode is formed of any single substance or alloy of gold, aluminum, and copper.

6. A liquid ejection head according to claim 1 or 2, comprising a plurality of the pad electrodes, wherein the plurality of the pad electrodes include a first pad electrode electrically connected to the first wiring and a second pad electrode electrically connected to the second wiring.

7. The plurality of the pad electrodes are arranged side by side, A liquid ejection head according to claim 1 or 2, wherein a ratio of a length of the connection region to a length of the pad electrode in a direction intersecting with an arrangement direction of the pad electrodes is 0.2 or less.

8. The plurality of the pad electrodes are arranged side by side, A liquid ejection head according to claim 1 or 2, wherein a ratio of a length of the mounting electrode to a length of the pad electrode in a direction intersecting with an arrangement direction of the pad electrodes is 0.5 or more.

9. The plurality of the pad electrodes are arranged side by side, A liquid ejection head according to claim 1 or 2, wherein an arrangement pitch of the plurality of the pad electrodes is 50 μm or less.

10. A liquid ejection head according to claim 1 or 2, wherein the plurality of the pad electrodes are arranged side by side along a peripheral portion on one side of the substrate.

11. Comprising a plurality of the piezoelectric elements, The substrate has a plurality of the discharge ports and a plurality of the pressure chambers respectively corresponding to the plurality of the piezoelectric elements, A liquid ejection head according to claim 1 or 2, wherein the first wiring is a common wiring common to the plurality of the piezoelectric elements, and the second wiring is an individual wiring individually used in the piezoelectric element.

12. A liquid ejection head according to claim 1 or 2, wherein the mounting electrode is formed in a layer different from the wiring electrically connected to the pad electrode.

13. A liquid ejection head according to claim 1 or 2, wherein the mounting electrode is formed of any one of gold, aluminum, and copper alone or an alloy.

14. A liquid ejection head according to claim 1 or 2, wherein a flexible substrate is electrically connected to the mounting electrode of the substrate.

15. A liquid ejection head according to claim 14, wherein the flexible substrate is joined using a non-conductive film or a non-conductive paste.

16. A substrate in which a pressure chamber communicating with a discharge port from which droplets are ejected is formed, A diaphragm provided on one surface side of the substrate, A piezoelectric element having a first electrode, a piezoelectric body, and a second electrode in this order on a surface of the diaphragm opposite to the substrate. A first wiring having an electrical resistivity lower than that of the first electrode and electrically connected to the first electrode, A second wiring having an electrical resistivity lower than that of the first electrode and electrically connected to the second electrode, Comprising, A method for manufacturing a liquid ejection head in which a pad electrode formed in the same layer as the first electrode is electrically connected to at least one of the first wiring and the second wiring, A step of forming a first layer on the diaphragm, A step of forming the first electrode and the pad electrode by patterning the first layer, A step of forming a second layer on top of the pad electrode, A step of forming the first wiring or the second wiring electrically connected to the pad electrode by patterning the second layer, Having, In the step of patterning the second layer, a portion of the second layer that overlaps with the pad region of the pad electrode to which a mounting electrode for applying an electrical signal to the piezoelectric element from the outside is joined is removed, and the first wiring or the second wiring electrically connected to the pad electrode is joined to a connection region different from the pad region of the pad electrode. A method for manufacturing a liquid ejection head.

17. A substrate in which a pressure chamber communicating with a discharge port from which droplets are discharged is formed, A diaphragm provided on one surface side of the substrate, A piezoelectric element having a first electrode, a piezoelectric body, and a second electrode in this order on the surface of the diaphragm opposite to the substrate, A first wiring having a hardness lower than that of the first electrode and electrically connected to the first electrode, A second wiring having a hardness lower than that of the first electrode and electrically connected to the second electrode, Comprising, A method for manufacturing a liquid ejection head in which a pad electrode formed in the same layer as the first electrode is electrically connected to at least one of the first wiring and the second wiring, A step of forming a first layer on the diaphragm, A step of forming the first electrode and the pad electrode by patterning the first layer, A step of forming a second layer on top of the pad electrode, A step of forming the first wiring or the second wiring electrically connected to the pad electrode by patterning the second layer, Having, In the step of patterning the second layer, a portion overlapping with the pad region of the pad electrode to which the mounting electrode for applying an electrical signal to the piezoelectric element from the outside is joined is removed from the second layer, and the first wiring or the second wiring electrically connected to the pad electrode is joined to a connection region different from the pad region of the pad electrode. A method for manufacturing a liquid ejection head.

18. After the step of forming the first wiring or the second wiring electrically connected to the pad electrode, a step of performing an electrical inspection by bringing a probe into contact with the pad region; After the step of performing the electrical inspection, a step of joining the mounting electrode to the pad region; The method for manufacturing a liquid ejection head according to claim 16 or 17, further comprising:

19. The method for manufacturing a liquid ejection head according to claim 18, further comprising a step of mounting a flexible substrate on the mounting electrode joined to the pad region using a non-conductive film or a non-conductive paste.

20. The method for manufacturing a liquid ejection head according to claim 16 or 17, comprising a plurality of the pad electrodes, and the plurality of pad electrodes include a first pad electrode electrically connected to the first wiring and a second pad electrode electrically connected to the second wiring.

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