JP2004188653A - Inkjet recording head and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording head which ensures continuity between a piezoelectric element and a diaphragm, and which prevents a fracture and a crack from being caused in the piezoelectric element during pressure jointing. <P>SOLUTION: In this inkjet recording head 40, an adhesive layer 65 for joining the piezoelectric element 44a and the diaphragm 43 together is formed of a thin layer part 65A with a thickness which allows the piezoelectric element 44a and the diaphragm 43 together to be joined together by bringing them into contact with each other, and a thick layer part 65B which has a thickness which allows the piezoelectric element 44a and the diaphragm 43 to be joined together by bringing them into noncontact with each other. Thus, the continuity between the piezoelectric element 44a and the diaphragm 43 is provided. Additionally, since conductive particles do not have to be contained in the adhesive layer 65, the fracture and the crack are prevented from being caused in the piezoelectric element 44a during the pressure jointing. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an ink jet recording head that presses ink in a pressure chamber by an operation of a piezoelectric element bonded to a vibration plate with a bonding layer to discharge ink droplets from nozzles, and a method of manufacturing the same.
[0002]
[Prior art]
As shown in FIG. 12, in a piezo-type ink jet recording head 100 that causes ink droplets to fly on recording paper or the like by the operation of a piezoelectric element 102, the piezoelectric element 102 and the diaphragm 104 form conductive particles 106 to ensure conduction. They are joined by a conductive adhesive 108 contained therein. (For example, see Patent Documents 1 to 3)
However, the conductive particles 106 contained in the conductive adhesive 108 and the filler 110 that is often added to this type of adhesive are not uniform in particle size, and large-sized particles 112 having a large particle size are not suitable. It may be included in the conductive adhesive 108.
[0003]
For this reason, when the piezoelectric element 102 is pressure-bonded to the vibration plate 104 via the foaming tape 114 and the fixing plate 116 for holding the piezoelectric element 102 by adhesion, the large-diameter particles 112 apply a concentrated load to the piezoelectric element 102. As a result, there is a problem that the piezoelectric element 102 is cracked or cracked.
[0004]
[Patent Document 1]
JP-A-62-82042
[Patent Document 2]
JP-A-10-315485
[Patent Document 3]
JP 2000-117992 A
[0005]
[Problems to be solved by the invention]
The present invention has been made in view of the above facts, and while ensuring conduction between the piezo element and the diaphragm, it is possible to prevent cracks and cracks from being generated in the piezo element when pressure-bonding the piezo element and the diaphragm. The purpose is to prevent it.
[0006]
[Means for Solving the Problems]
The inkjet recording head according to claim 1, wherein the vibration plate forming a part of the wall surface of the pressure chamber provided with the nozzle and the piezoelectric element are bonded by a bonding layer, and the vibration of the vibration plate is caused by the operation of the piezoelectric element. An ink jet recording head that pressurizes ink in the pressure chamber and ejects ink droplets from the nozzles, wherein the bonding layer has a thickness that allows the diaphragm and the piezoelectric element to come into contact with each other and bond. It is characterized by comprising a layer portion and a thick layer portion having a thickness for joining the vibration plate and the piezoelectric element in a non-contact manner.
[0007]
In the ink jet recording head according to the first aspect, the piezoelectric element and the vibration plate are joined by a joining layer formed of a thin layer portion and a thick layer portion. Since the piezoelectric element and the vibration plate are joined by the thin layer portion in a state of contact, the piezoelectric element and the vibration plate are electrically connected even if the joining layer does not contain conductive particles. Therefore, when the piezoelectric element is pressure-bonded to the vibration plate, a concentrated load is not applied to the piezoelectric element via the conductive particles, and no crack or crack occurs.
[0008]
Further, the piezoelectric element and the vibration plate are joined in a non-contact manner by a thick layer portion. That is, since a strong bonding layer is formed by the thick layer portion on the bonding surface between the piezoelectric element and the vibration plate, the bonding strength between the piezoelectric element and the vibration plate can be secured.
[0009]
The ink jet recording head according to claim 2, wherein the thick layer portion is provided in a portion facing the pressure chamber, and the thin layer portion is provided in the pressure chamber. Characterized by being provided at a portion facing a partition wall that forms
[0010]
In the ink jet recording head according to the second aspect, since the thick layer portion is provided in a portion facing the pressure chamber, even if this portion is deformed by the operation of the piezoelectric element, the piezoelectric element is separated from the diaphragm. There is no.
[0011]
Further, since the thin layer portion is provided at a portion facing the partition wall forming the pressure chamber, conduction between the piezoelectric element and the diaphragm is ensured. Since this portion is not deformed by the operation of the piezoelectric element, the piezoelectric element does not peel off from the diaphragm even if the thin layer portion does not contact the entire surface of the joining surface between the piezoelectric element and the diaphragm.
[0012]
The inkjet recording head according to claim 3, wherein the thick layer portion is provided in a central portion of the pressure chamber, and the thin layer portion is provided in the thick layer portion. Is provided around the periphery.
[0013]
In the ink jet recording head according to the third aspect, since the thick layer portion is provided at the center of the pressure chamber, the piezoelectric element does not peel off from the diaphragm even if this portion is deformed by the operation of the piezoelectric element.
[0014]
In addition, since the thin layer portion is provided around the piezoelectric element, conduction between the piezoelectric element and the vibration plate can be ensured, and the adhesive that becomes the thin layer portion when the piezoelectric element and the vibration plate are pressure-joined to each other. It can be prevented from protruding from the joint. The portion of the diaphragm where the thin layer portion is provided has a smaller amount of deformation than the central portion, so that the piezoelectric element does not peel off from the diaphragm.
[0015]
An ink jet recording head according to a fourth aspect is the ink jet recording head according to any one of the first to third aspects, wherein the thickness of the thick layer portion is 2 μm or less.
[0016]
In the ink jet recording head according to the fourth aspect, the thickness of the thick layer portion is 2 μm or less. Experiments described later have confirmed that when the thickness of the bonding layer is 2 μm or more, the bonding layer buffers and absorbs the displacement of the piezoelectric element. Therefore, the diaphragm can be reliably displaced by setting the thickness of the thick layer portion to 2 μm or less. Here, the thickness of the thick portion refers to the average thickness of the entire thick portion.
[0017]
An ink jet recording head according to a fifth aspect is the ink jet recording head according to any one of the first to fourth aspects, wherein the thickness of the thin layer portion is 0.5 μm or less.
[0018]
In the inkjet recording head according to the fifth aspect, the thickness of the thin layer portion is 0.5 μm or less. Normally, the surface roughness of the piezoelectric element and the vibration plate is set to several μm, so that the thin layer portion is in a state of being embedded in concave and convex portions of the joint surface between the piezoelectric element and the vibration plate, and the piezoelectric element and the vibration plate The top of the surface roughness is brought into contact and joined. As a result, the piezoelectric element and the diaphragm conduct. The thickness of the thin layer portion refers to the average thickness of the entire thin layer portion.
[0019]
The inkjet recording head according to claim 6, wherein the surface roughness of at least one of the joining surfaces of the piezoelectric element and the vibration plate is 2 to 6 μm. It is characterized by being.
[0020]
In the ink jet recording head according to claim 6, when the surface roughness of at least one of the joining surfaces of the piezoelectric element and the vibration plate is 2 to 6 μm, and the thickness of the thin layer portion is 0.5 μm or less, It has been confirmed that the piezoelectric element and the diaphragm can be conducted.
[0021]
The inkjet recording head according to claim 7 is the inkjet recording head according to any one of claims 1 to 6, wherein the bonding layer is formed of an adhesive that does not contain fine particles such as fillers and conductive particles. It is characterized by having.
[0022]
In the ink jet recording head according to the seventh aspect, since the bonding layer is formed of an adhesive containing no fine particles such as fillers and conductive particles, the bonding layer is concentrated on the piezoelectric element when the piezoelectric element is pressure-bonded to the vibration plate. No load is applied. Therefore, cracks and cracks do not occur in the piezoelectric element.
[0023]
The ink jet recording head according to claim 8 is the ink jet recording head according to claim 7, wherein the bonding layer is formed of a thermosetting epoxy adhesive.
[0024]
In the ink jet recording head according to claim 8, since the bonding layer is formed of a thermosetting epoxy adhesive, the adhesive is cured by heating the piezoelectric element and the vibration plate together with pressurization. And the diaphragm are joined. Although the bonding layer is formed with an epoxy (insulating) adhesive, the piezoelectric element and the diaphragm are electrically connected because they are in contact with each other by the thin layer portion.
[0025]
The inkjet recording head according to claim 9, wherein the vibration plate forming a part of the wall surface of the pressure chamber provided with the nozzle and the piezoelectric element are bonded by a bonding layer, and the vibration plate is deformed by the operation of the piezoelectric element. An ink jet recording head that pressurizes the ink in the pressure chamber to eject ink droplets from the nozzles, wherein the bonding layer is formed of an adhesive having a particle diameter of 2 μm or less, Is 2 μm or less.
[0026]
In the ink jet recording head according to the ninth aspect, the bonding layer is formed of an adhesive containing only microparticles having a uniform particle size of 2 μm or less. Therefore, when the piezoelectric element and the diaphragm are pressure-bonded, the piezoelectric element is not locally subjected to a concentrated load, so that the piezoelectric element does not crack or crack.
[0027]
Further, since the particle size of the particles contained in the adhesive is 2 μm or less, the thickness of the bonding layer can be 2 μm or less, and the displacement of the piezoelectric element can be efficiently transmitted to the diaphragm.
[0028]
The method of manufacturing an ink jet recording head according to claim 10, wherein the vibration plate forming a part of the wall surface of the pressure chamber provided with the nozzle and the piezoelectric element are joined by a bonding layer, and the vibration plate is actuated by the operation of the piezoelectric element. A method for manufacturing an ink jet recording head that pressurizes ink in the pressure chamber by deforming and ejects ink droplets from the nozzles, wherein an adhesive is applied to at least one of the piezoelectric element and the vibration plate. Pressurized and cured, forming the bonding layer with a thin layer portion that joins the piezoelectric element and the vibration plate in contact with each other, and a thick layer portion that joins the piezoelectric element and the vibration plate in a non-contact manner. Features.
[0029]
In the method of manufacturing an ink jet recording head according to the tenth aspect, the piezoelectric element and the vibration plate are joined by being brought into contact with each other at the thin layer portion, and are joined without contact at the thick layer portion. Accordingly, even if the bonding layer is formed of any adhesive, the piezoelectric element and the vibration plate are reliably conducted, and the bonding strength between the piezoelectric element and the vibration plate is ensured. Further, since there is no need to include fine particles such as conductive particles in the adhesive forming the bonding layer, the piezoelectric element is not damaged by a concentrated load when the piezoelectric element and the diaphragm are pressure-bonded.
[0030]
The method for manufacturing an ink jet recording head according to claim 11, wherein the thick layer portion is formed at a portion facing the pressure chamber, and the thin layer is formed. The part is formed at a portion facing the partition wall forming the pressure chamber.
[0031]
In the method of manufacturing an ink jet recording head according to the eleventh aspect, the piezoelectric element and the vibration plate are joined in a non-contact manner at a portion facing the pressure chamber, and are brought into contact and joined at a portion facing the partition wall forming the pressure chamber. . This ensures that the piezoelectric element and the vibrating plate are electrically connected to each other even if the bonding layer is formed of any adhesive, and that even if the portion of the vibrating plate facing the pressure chamber is deformed by the operation of the piezoelectric element, the vibrating plate remains It does not come off.
[0032]
The method of manufacturing an ink jet recording head according to claim 12, wherein the thick layer portion is formed in a central portion of the pressure chamber, and the thin layer portion is formed. Is formed around the thick layer portion.
[0033]
In the method for manufacturing an ink jet recording head according to the twelfth aspect, the piezoelectric element and the vibration plate are joined in a non-contact manner at the center of the pressure chamber, and are brought into contact with each other at the periphery thereof. This ensures that the piezoelectric element and the vibrating plate are electrically connected to each other even if the bonding layer is formed of any adhesive, and that even if the portion of the vibrating plate facing the pressure chamber is deformed by the operation of the piezoelectric element, the vibrating plate remains It does not come off. Further, the adhesive forming the thin layer portion can be prevented from protruding from the joint portion.
[0034]
A method for manufacturing an ink jet recording head according to a thirteenth aspect is the method for manufacturing an ink jet recording head according to any one of the tenth to twelfth aspects, wherein the adhesive is applied at a thickness of 2 to 5 μm. And
[0035]
In the method of manufacturing an ink jet recording head according to a thirteenth aspect, an adhesive is applied to at least one of the piezoelectric element and the diaphragm with a thickness of 2 to 5 μm, and the piezoelectric element and the diaphragm are pressure-bonded. Thus, it has been confirmed that the piezoelectric element and the diaphragm can be joined by contact in the thin layer portion, and the piezoelectric element and the diaphragm can be joined in the non-contact manner in the thick layer portion.
[0036]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a first embodiment will be described with reference to the drawings.
[0037]
As shown in FIG. 1, an ink jet recording head 10 according to the first embodiment is mounted on an ink jet recording apparatus 1. In the inkjet recording apparatus 10, the recording paper 2 is transported in the sub-scanning direction (the direction of arrow B in the figure) while the inkjet recording head 10 scans in the main scanning direction (the direction of the arrow A in the figure). Ink droplets are ejected from 10 to the recording paper 2. Thus, an image is recorded on the entire surface of the recording paper 2.
[0038]
As shown in FIGS. 2 and 3, the ink jet recording head 10 includes a nozzle plate 11 in which a plurality of nozzles 11a (diameter 30 ± 0.5 μm) are formed in a matrix (64 rows × 4 columns). I have. A pressure chamber plate 12 is adhered to the nozzle plate 11. Further, a diaphragm 13 (made of stainless steel) is adhered to the back surface of the pressure chamber plate 12 that is adhered to the nozzle plate 11. The pressure chamber plate 12 is formed with four tapered partition walls 12b gradually narrowing from the vibration plate 13 toward the nozzle plate 11. The pressure chambers 12a are formed by the partition walls 12b, the nozzle plate 11, and the vibration plate 13. And the same number as the nozzles 11a.
[0039]
A piezoelectric element 14a having a square shape (one side of 500 ± 10 μm) faces each pressure chamber 12a on the back surface of the bonding surface of the vibration plate 13 with the pressure chamber plate 12 such that the nozzle 11a is located at the center. They are positioned and arranged. Further, electrode layers 34a and 34b are formed on the upper and lower surfaces of the piezoelectric element 14a.
[0040]
The electrode layer 34a is mechanically and electrically joined to the wiring layer 17 by the solder ball bumps 16, and the electrode layer 34b is adhered to the diaphragm 13 in an electrically conductive manner by an adhesive layer 35 (described later). As a result, a drive voltage from a control unit (not shown) is applied to the piezoelectric element 14a via the wiring layer 17 and the solder ball bumps 16.
[0041]
Next, a method for manufacturing the inkjet recording head 10 will be described.
[0042]
First, the nozzle plate 11 is joined to the pressure chamber plate 12 with the nozzle 11a shown in FIG. Then, the vibration plate 13 is joined to the back surface of the joining surface of the pressure chamber plate 12 and the nozzle plate 11.
[0043]
Next, the piezoelectric element 14a is manufactured. First, as shown in FIG. 4A, a piezoelectric plate 21 (thickness: 30 μm, made of lead zirconate titanate) is bonded to a substrate 23 using an adhesive film 22 having a thermal foaming property. Next, a photosensitive film 24 (urethane-based) is attached to the whole of the piezoelectric plate 21 and is exposed while the photosensitive film 24 is covered with a grid-like mask (not shown). On both surfaces of the piezoelectric plate 21, an electrode layer 34a (a 0.2 μm metal thin film made of Cr) and an electrode layer 34b (a 0.1 μm metal film made of Au) are formed in advance by a sputtering method.
[0044]
Then, as shown in FIG. 4B and FIG. 5, the photosensitive film 24 of the square-shaped portion which has been exposed and cured is left, and the other portions are removed to form the groove pattern 19c extending in the matrix direction. I do. As a result, four piezoelectric element patterns 19a and a dummy pattern 19b surrounding the piezoelectric element pattern 19a are formed in the central portion.
[0045]
Next, silicon carbide abrasive grains (abrasive particle diameter: for example, 20 μm) are sprayed at a predetermined pressure to perform sandblasting. Thereby, as shown in FIG. 4C, the piezoelectric plate 21 is ground at the groove pattern 19c to form the separation groove 18. By the separation groove 18, the piezoelectric element unit 14 is formed on the piezoelectric plate 21 by being separated into the piezoelectric element 14a and the dummy element 14b.
[0046]
Then, the photosensitive film 24 is peeled from the piezoelectric element unit 14. Thereafter, the piezoelectric element unit 14 is positioned on the vibration plate 13 and joined by a method of aligning a positioning mark (not shown) formed in advance with a microscope.
[0047]
Then, an adhesive is applied to the surface of the electrode layer 34b or the vibration plate 13 to a thickness of 2 to 5 μm, and the piezoelectric element 14a and the vibration plate 13 are bonded and fixed by heating under pressure. The pressure was 1 MPa (Pascal) applied to the plane area of the piezoelectric element 14a, and the heating temperature was 120 degrees.
[0048]
As the adhesive, a conductive adhesive to which fine particles such as fillers or conductive particles having a particle size of 2 μm or less are added, and the thickness of the adhesive layer 35 after bonding and fixing (average of the entire adhesive layer 35) is used. (Thickness) is 2 μm or less.
[0049]
This is because the displacement of the piezoelectric element 14a is absorbed and buffered by the adhesive layer 35 when the thickness of the adhesive layer 35 increases, as described later. This is because the size of the piezoelectric element 14a becomes large, and the displacement of the piezoelectric element 14a is transmitted to the vibration plate 13 unevenly. Therefore, the adhesive layer 35 is formed as described above to maintain the performance of the diaphragm.
[0050]
In addition, since the adhesive layer 35 does not contain particles having a large diameter exceeding 2 μm, cracks and cracks occur in the piezoelectric element 14a when the piezoelectric element 14a and the vibration plate 13 are pressure-bonded. Such a load is not applied.
[0051]
After bonding the piezoelectric element unit 14 and the vibration plate 13 as described above, the substrate 23 is separated from the piezoelectric element 14a and the dummy element 14b. Here, the adhesive film 22 has such a property that when heated at a predetermined temperature after bonding, the adhesive film 22 foams to reduce the adhesive strength. Utilizing this property, the adhesive film 22 is heated at a predetermined temperature, and the substrate 23 is separated from the piezoelectric element 14a.
[0052]
Finally, as shown in FIG. 2, the electrode layer 34a of the piezoelectric element 14a is connected to the wiring layer 17 connected to the control unit (not shown) via the solder ball bump 16. In the ink jet recording apparatus 1 equipped with the ink jet recording head 10 manufactured as described above, the piezoelectric element 14a was satisfactorily driven at the driving voltage of 30 V and the frequency of 30 kHz, and the ink droplets were satisfactorily ejected from the corresponding nozzle 11a. .
[0053]
In addition, as shown in the table of FIG. 6, when the thickness of the adhesive layer 35 was changed from 1 to 5 μm and a printing test was performed, when the thickness of the adhesive layer 35 exceeded 2 μm, It was confirmed that the performance of the piezoelectric element 14a deteriorated.
[0054]
Next, a second embodiment will be described.
[0055]
As shown in FIGS. 7 and 8, the inkjet recording head 40 is provided with a nozzle plate 41 in which a plurality of nozzles 41a (diameter 30 ± 0.5 μm) are formed in a matrix (64 rows × 4 columns). I have. A pressure chamber plate 42 is adhered to the nozzle plate 41. Further, a vibration plate 43 (made of stainless steel) is adhered to the back surface of the pressure chamber plate 42 that is adhered to the nozzle plate 41. The pressure chamber plate 42 is formed with four tapered pressure chamber partition walls 42b gradually narrowing from the vibration plate 43 toward the nozzle plate 41. The pressure chamber partition 42b, the nozzle plate 41, and the vibration plate 43 Pressure chambers 42a are formed, and are provided by the same number as the nozzles 41a.
[0056]
A plurality of piezoelectric elements 44a are arranged in a matrix on the back surface of the bonding surface of the vibration plate 43 with the pressure chamber plate 42 so as to face each pressure chamber 42a. The piezoelectric element 44a has a rectangular shape (short side 450 ± 10 μm, long side 750 ± 50 μm), and one end in the longitudinal direction is located at a portion of the diaphragm 43 facing the pressure chamber 42a, and the other end in the longitudinal direction. The portion is located at a portion facing the pressure chamber partition wall 42b. Both ends in the width direction are narrower than the pressure chamber 42a. Thus, the deformation of the portion of the piezoelectric element 44a facing the pressure chamber 42a is not hindered by the pressure chamber partition 42b, so that the piezoelectric element 44a can be displaced efficiently.
[0057]
Then, an electrode layer 64b (0.1 μm thin metal film made of Au) is formed on the surface of the piezoelectric element 44a that is joined to the vibration plate 43, and the electrode layer 64a (0.2 μm made of Cr) is formed on the back surface of the joining surface. Metal thin film) is formed. The electrode layer 64a is mechanically and electrically joined to the flexible wiring board 47 by the solder ball bump 46, and the electrode layer 64b is adhesively fixed to the diaphragm 43 so as to be conductive by an adhesive layer 65 (described later). . As a result, a drive voltage from a control unit (not shown) is applied to the piezoelectric element 44a via the flexible wiring board 47.
[0058]
Next, a method for manufacturing the ink jet recording head 40 will be described.
[0059]
The manufacturing method of the second embodiment is basically the same as the manufacturing method of the first embodiment, except that the remaining dummy element 61 is provided, the positioning method, and the method of applying the adhesive. . In particular, differences between the bonding methods will be described in detail.
[0060]
First, in order to make the width of the separation groove 62 uniform, in the present embodiment, as shown in FIG. 8, the remaining dummy element is disposed between the adjacent piezoelectric elements 44a and between the piezoelectric element 44a and the dummy element 60. 61 were provided. As for the positioning, as shown in FIGS. 8 and 9, alignment marks 66 are formed on the piezoelectric plate 51, positioning marks 67 are formed on the pressure chamber plate 12, and through holes 68 are formed on the substrate 53 corresponding to the alignment marks 66. The vibration plate 43 is formed with a through hole 69 corresponding to the positioning mark 67. Then, the alignment mark 66 and the positioning mark 67 are aligned with a microscope through the through holes 68 and 69, and the piezoelectric element 44a is positioned and joined on the vibration plate 43 with high accuracy.
[0061]
Next, as shown in FIGS. 8 and 10, a thermosetting epoxy adhesive containing no fine particles such as fillers or conductive particles on at least one surface of the electrode layer 64b and the diaphragm 43 is averaged in this embodiment. The piezoelectric element 44a and the diaphragm 43 are bonded and fixed by applying a pressure of 3.5 μm and heating under pressure. As in the first embodiment, the pressing force was 1 MPa (Pascal) with respect to the plane area of the piezoelectric element 44a, and the heating temperature was 120 degrees.
[0062]
At the time of this adhesive fixing, as the pressing force is increased, the portion of the piezoelectric element 44a or the diaphragm 43 facing the pressure chamber 42a cannot receive the pressing force because the pressure chamber 42a is a cavity, and FIG. Deform as shown. Conversely, in the portion facing the pressure chamber partition wall 42b, a sufficient pressing force acts to make the adhesive layer 65 thin. By utilizing this phenomenon, a thick layer portion 65A having a thickness of 2 μm or less is formed in a portion of the adhesive layer 65 facing the pressure chamber 42a, and faces the periphery of the thick layer portion 65A and the pressure chamber partition 42b. A thin layer portion 65B having a thickness of 0 to 0.5 μm is formed in the portion. Here, the thickness of the thick layer portion 65A refers to the average thickness of the entire thick layer portion 65A, and the thickness of the thin layer portion 65B refers to the thickness of the entire thin layer portion 65B. The bonding surface of the piezoelectric element 44a is finished with a surface roughness of 6 μm, and the bonding surface of the diaphragm 43 is finished with a surface roughness of 2 μm.
[0063]
As a result, as shown in FIG. 11A, in the thin layer portion 65B, the uneven protrusions 44b on the bonding surface of the piezoelectric element 44a and the uneven protrusions 43b on the surface of the vibration plate 43 come into contact. Therefore, even if the adhesive layer 65 is an epoxy adhesive containing no conductive particles, conduction between the piezoelectric element 44a and the diaphragm 43 is ensured.
[0064]
In the thin layer portion 65B, the piezoelectric element 44a and the vibration plate 43 are joined in a state where the adhesive is embedded in the concave and convex portions of the bonding surface of the piezoelectric element 44a and the vibration plate 43. Therefore, even if the diaphragm 43 is deformed by the operation of the piezoelectric element 44a, the diaphragm 43 does not peel off from the diaphragm 43.
[0065]
Therefore, under the condition that the surface roughness of the bonding surface between the piezoelectric element 44a and the vibration plate 43 is 2 to 6 μm and the thickness of the thin layer portion 65B is 0.5 μm or less, conduction between the piezoelectric element 44a and the vibration plate 43 can be ensured. Thus, the piezoelectric element 44a and the diaphragm 43 can be securely bonded.
[0066]
In addition, as shown in FIG. 11B, in the thick layer portion 65A, the piezoelectric element 44a and the vibration plate 43 are not in contact, and the thick layer portion 65A joins the entire bonding surface of the piezoelectric element 44a and the vibration plate 43. ing. Thereby, since the adhesive strength is secured, even if the vibration plate 43 is deformed by the operation of the piezoelectric element 44a, the piezoelectric element 44a does not peel off from the vibration plate 43.
[0067]
As described above, by preventing the adhesive layer 65 from containing fine particles such as fillers and conductive particles, when the piezoelectric element 44a and the vibration plate 43 are pressure-bonded, a concentrated load is locally applied to the piezoelectric element 44a. This prevents the piezoelectric element 44a from being cracked or cracked. In the present embodiment, the adhesive is applied in a thickness of 3.5 μm, but when applied in a thickness range of 2 to 5 μm, the same effect as described above is obtained.
[0068]
In the ink jet recording head 40 manufactured as described above, the piezoelectric element 14a was favorably driven at a driving voltage of 30 V and a frequency of 30 kHz, and ejected ink droplets from the corresponding nozzle 41a.
[0069]
In the first and second embodiments, the piezoelectric element has a square shape or a rectangular shape. However, the present invention is not limited to this, and similar effects can be obtained with other shapes such as a circular shape and an elliptical shape. In addition, the piezoelectric elements are arranged in a matrix, but the present invention is not limited to this, and other arrangements such as arranging them in a circular shape as a whole are also applicable.
[0070]
【The invention's effect】
Since the present invention is configured as described above, conduction between the piezoelectric element and the vibration plate can be ensured, and generation of cracks and cracks in the piezoelectric element when the piezoelectric element is pressure-bonded to the vibration plate can be prevented.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an ink jet recording apparatus equipped with an ink jet recording head according to a first embodiment.
FIG. 2 is a cross-sectional view illustrating the inkjet recording head according to the first embodiment.
FIG. 3 is a view taken in the direction of arrows 3-3 in FIG. 2;
FIG. 4A is a cross-sectional view illustrating a step of forming a piezoelectric element of the inkjet recording head according to the first embodiment.
FIG. 3B is a cross-sectional view illustrating a step of forming the piezoelectric element of the inkjet recording head according to the first embodiment.
FIG. 3C is a cross-sectional view illustrating a step of forming the piezoelectric element of the inkjet recording head according to the first embodiment.
FIG. 5 is a plan view showing a piezoelectric element pattern of the inkjet recording head according to the first embodiment.
FIG. 6 is a table showing determination of the performance of the piezoelectric element based on the thickness of the adhesive layer of the inkjet recording head according to the first embodiment.
FIG. 7 is a cross-sectional view (a view taken along the arrow line 7-7 in FIG. 8) showing the ink jet print head according to the second embodiment.
8 is a view taken in the direction of the arrow 8-8 in FIG. 7;
FIG. 9 is a cross-sectional view illustrating a step of joining a piezoelectric element and a diaphragm of an ink jet recording head according to a second embodiment.
FIG. 10 is an enlarged cross-sectional view illustrating a step of joining a piezoelectric element and a diaphragm of an ink jet recording head according to a second embodiment.
FIG. 11A is an enlarged cross-sectional view illustrating a thin layer portion of an adhesive layer that joins a piezoelectric element and a diaphragm of an ink jet recording head according to a second embodiment.
FIG. 4B is an enlarged cross-sectional view illustrating a thick layer portion of an adhesive layer that joins the piezoelectric element and the diaphragm of the ink jet recording head according to the second embodiment.
FIG. 12 is a cross-sectional view illustrating a bonding step of a piezoelectric element and a diaphragm of an ink jet recording head according to a conventional example.
[Explanation of symbols]
10 Inkjet recording head
11a nozzle
12a Pressure chamber
13 diaphragm
14a Piezoelectric element
35 Adhesive layer (joining layer)
40 inkjet recording head
41a nozzle
42a pressure chamber
42b Pressure chamber partition (partition)
43 diaphragm
44a Piezoelectric element
65 Adhesive layer (joining layer)
65A thick part
65B thin layer

Claims (13)

A vibration plate forming a part of the wall surface of the pressure chamber provided with the nozzle and the piezoelectric element are joined by a bonding layer, and the operation of the piezoelectric element deforms the vibration plate to pressurize ink in the pressure chamber. An inkjet recording head that ejects ink droplets from the nozzles,
The bonding layer,
A thin layer portion having a thickness to contact and join the vibration plate and the piezoelectric element,
A thick layer portion having a thickness for joining the vibration plate and the piezoelectric element in a non-contact manner,
An ink jet recording head formed of: The said thick layer part is provided in the part which faces the said pressure chamber, The said thin layer part is provided in the part which faces the partition which forms the said pressure chamber, The claim of Claim 1 characterized by the above-mentioned. Ink jet recording head. 2. The ink jet recording head according to claim 1, wherein the thick layer portion is provided at a center of the pressure chamber, and the thin layer portion is provided around the thick layer portion. 3. 4. The ink jet recording head according to claim 1, wherein the thickness of the thick layer portion is 2 μm or less. 5. The ink jet recording head according to claim 1, wherein the thickness of the thin layer portion is 0.5 [mu] m or less. 6. The ink jet recording head according to claim 1, wherein the surface roughness of at least one of the joining surfaces of the piezoelectric element and the vibration plate is 2 to 6 [mu] m. The ink jet recording head according to any one of claims 1 to 6, wherein the bonding layer is formed of an adhesive that does not contain fine particles such as fillers and conductive particles. The inkjet recording head according to claim 7, wherein the bonding layer is formed of a thermosetting epoxy adhesive. A vibration plate forming a part of the wall surface of the pressure chamber provided with the nozzle and the piezoelectric element are joined by a bonding layer, and the operation of the piezoelectric element deforms the vibration plate to pressurize ink in the pressure chamber. An inkjet recording head that ejects ink droplets from the nozzles,
The ink jet recording head according to claim 1, wherein the bonding layer is formed of an adhesive having a particle diameter of the contained fine particles of 2 μm or less and a thickness of 2 μm or less. A vibration plate forming a part of the wall surface of the pressure chamber provided with the nozzle and the piezoelectric element are joined by a bonding layer, and the operation of the piezoelectric element deforms the vibration plate to pressurize ink in the pressure chamber. A method of manufacturing an ink jet recording head for discharging ink droplets from the nozzles,
An adhesive is applied to at least one of the piezoelectric element and the vibrating plate to be cured by pressure, and the bonding layer is a thin layer portion that is brought into contact with the piezoelectric element and the vibrating plate to be bonded. A method for manufacturing an ink jet recording head, comprising: forming a diaphragm with a thick layer portion joined in a non-contact manner. The inkjet recording according to claim 10, wherein the thick layer portion is formed in a portion facing the pressure chamber, and the thin layer portion is formed in a portion facing a partition wall forming the pressure chamber. Head manufacturing method. The method according to claim 10, wherein the thick layer is formed at a center of the pressure chamber, and the thin layer is formed around the thick layer. 13. The method according to claim 10, wherein the adhesive is applied to a thickness of 2 to 5 [mu] m.

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