JP3870812B2 - Manufacturing method of multilayer piezoelectric element - Google Patents

Description

[0001]
【Technical field】
The present invention relates to a method for manufacturing a laminated piezoelectric element having first and second protective layers on both ends of a drive layer configured by alternately laminating piezoelectric layers and internal electrode layers.
[0002]
[Prior art]
There is known a piezoelectric element including a driving layer in which piezoelectric layers and internal electrode layers are alternately stacked, and first and second protective layers provided at both ends of the driving layer in the stacking direction.
In recent years, the piezoelectric element is sometimes used as a drive source for a fuel injection device in an automobile engine. The piezoelectric element used for this purpose is required to have a high output at a low voltage and to be excellent in reliability and durability.
Piezoelectric elements used for such applications are often configured to exhibit high output by reducing the thickness of the piezoelectric layer and increasing the number of stacked piezoelectric layers (several hundred layers).
[0003]
[Problems to be solved]
By the way, a laminated piezoelectric element in which the first and second protective layers are provided on both ends of the drive layer is often produced by bonding a separately prepared protective layer to the drive layer after firing in a subsequent process. (Refer to a comparative example described later).
[0004]
However, the protective layer provided by this method has some problems.
(1) It takes time and labor to perform the post-process, which is disadvantageous in terms of production efficiency and cost.
(2) There is a possibility that the output of the piezoelectric element may be reduced at the adhesion portion with the protective layer.
(3) In a harsh environment such as for fuel injection of an automobile internal combustion engine, the shearing force cannot be sufficiently relaxed only by adhering the protective layer.
[0005]
As another method for forming a protective layer, JP-A-8-8471 proposes a method in which a protective layer is produced as a press-molded product, which is pressure-bonded to a driving layer before firing, and both are integrally fired. However, piezoelectric elements that have a very large number of layers and reach hundreds of layers may be deformed due to the difference in shrinkage between the drive layer and the protective layer during firing, resulting in delamination. .
[0006]
Further, in the piezoelectric element disclosed in Japanese Patent Laid-Open No. 9-270540, the protective layer has the same configuration as the driving layer. That is, like the drive layer, the protective layer is in a state where the piezoelectric layer and the internal electrode layer are alternately laminated, but unlike the drive layer, the protective layer does not have a side electrode for supplying power from the outside. . Therefore, the piezoelectric layer of the protective layer does not expand and contract.
[0007]
The problems with the multilayer piezoelectric element with this configuration are that a protective layer with high strength cannot be obtained when the piezoelectric layer constituting the driving layer is very thin, and the electrode material used for the internal electrode layer of the protective layer is wasted. In particular, silver / palladium used as an electrode material is expensive and not economical.
[0008]
The present invention has been made in view of such conventional problems, and provides a method for manufacturing a multilayer piezoelectric element having few defects such as cracks and delamination, excellent durability, excellent production efficiency, and low cost. It is something to be offered.
[0009]
[Means for solving problems]
According to the present invention, there is provided a multi-layer piezoelectric element including a driving layer in which piezoelectric layers and internal electrode layers are alternately stacked, and first and second protective layers on both end surfaces in the stacking direction of the driving layer.
A first first green portion of the protective layer of the first unsintered sheet are layered with a prescribed number of adhesive layers, provided the printing portion internal electrode layer with respect to green portion of the first stacked through a third green part the green sheet for a piezoelectric layer laminated through a predetermined number adhesive layer, the predetermined number adhesive layer and a second green sheet to green part of the third a method of manufacturing by firing become more green laminate and the second of the second green portion of the protective layer, and
In obtaining the unfired laminate,
Prepare at least stacked aliquot capable piezoelectric element to one producing the first and second green sheet, a large green sheet having a size capable of collecting green sheet for a piezoelectric layer,
The printing portion internal electrode layer formed by printing on the portion to be a green sheet for a piezoelectric layer in the large green sheet, the first and second green sheet in the large green sheet, the green sheet for a piezoelectric layer An adhesive layer is printed on
Next, the first unfired sheet is punched from the large unfired sheet, and at the same time, a predetermined number of sheets are stacked and pressure-bonded to form the first unfired portion, and then the piezoelectric layer unfired sheet is punched at the same time as the predetermined number of sheets. the laminated crimped to the first green part to form a third green part, further followed by the second green sheet punched out at the same time a predetermined number of sheets stacked crimped to the third green part The present invention is a method for manufacturing a laminated piezoelectric element, characterized in that the second unfired part is formed.
In the present specification, hereinafter, “first...” Is sometimes referred to as “first...” And “no” may be omitted, but the meaning is the same. This applies not only to “first” but also to “second” and “third”. In addition, the expressions “first and second...”, “First and second...”, And “first and second. And second ... ".
[0010]
The function and effect of the present invention will be described.
In the manufacturing method according to the present invention, the first and second protective layers, the first and second unfired sheets serving as the driving layers, and the unfired piezoelectric layer sheet are collected from one large unfired sheet by firing. To do. Since it is collected from the same sheet, there is little difference in material and properties, and it is difficult for firing shrinkage difference between the part applied to the protective layer and the part applied to the drive layer during firing, preventing cracks and delamination caused by this. It is possible to reduce the strength.
[0011]
In addition, since the first and second green sheets and the piezoelectric layer green sheet are bonded using the adhesive layer, the first and second green sheets and the piezoelectric layer green sheet are applied during pressure bonding. The pressure can be lowered. Increased bonding pressure causes defects in the unfired sheet and causes microcracks after firing. According to the manufacturing method of the present invention that enables bonding at a low pressure, the above-mentioned problems can be prevented.
Therefore, cracks and delamination due to the above problems can be prevented, and the strength of the multilayer piezoelectric element is hardly reduced.
[0012]
In the manufacturing method according to the present invention, the first and second unfired sheets and the unfired piezoelectric layer sheet are punched from the large unfired sheet and are laminated at the same time to form an unfired laminate.
Therefore, there is no need to perform the process of collecting from the large green sheet and the process of laminating separately. Therefore, the production efficiency of the unfired laminate is increased and the production speed is also improved. Therefore, the manufacturing cost is also low.
Furthermore, since the protective layer is made of the same material as the piezoelectric layer and does not include an expensive material such as the internal electrode layer, the raw material cost is low.
[0013]
As described above, according to the present invention, it is possible to obtain a method for manufacturing a multilayer piezoelectric element that has few defects such as cracks and delamination, is excellent in durability, is excellent in production efficiency, and is low in cost.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
In the first aspect of the invention (invention 1), the piezoelectric layer and the first and second protective layers can be made of a dielectric material which is usually used in a piezoelectric element. PZT (lead zirconate titanate) is often used, but other materials can be used.
In addition, various electrode materials such as Pt and Ag can be used for the internal electrode layer.
[0015]
The adhesive layer is preferably made of a paste made of the same or similar material as the piezoelectric layer and the first and second protective layers.
If the properties of the adhesive layer are different from those of the piezoelectric layer and the first and second protective layers, cracks and delamination may occur due to firing shrinkage and the like.
[0016]
The adhesive layer preferably has a dry thickness of 3 to 17 μm.
The dry thickness is the thickness after the drying shrinkage is completed, not immediately after the print formation.
When this thickness is less than 3 μm, the liquid component (binder, etc.) of the adhesive layer permeates into a large unfired sheet and the like, and the adhesive force may be lost by drying before bonding. Also, it is difficult to print and form an adhesive layer of less than 3 μm.
Furthermore, when it is thicker than 17 μm, it is difficult to form a print, and there is a possibility that it protrudes from the side surface after lamination. The adhesive layer is more preferably 7 μm.
[0017]
Further, the longitudinal direction of the large green sheet has a length sufficient to collect the first and second green sheets and the piezoelectric layer green sheet necessary for producing at least one laminated piezoelectric element. It is preferable.
From the viewpoint of production efficiency, it is preferable to prepare a long, large unfired sheet and continuously produce a large number of unfired laminates (see Examples).
[0018]
【Example】
Embodiments of the present invention will be described below with reference to the drawings.
(Example)
In this example, as shown in FIG. 1, the driving layers 13 in which the piezoelectric layers 132 and the internal electrode layers 131 are alternately stacked, and the first and second protective layers 11, A method of manufacturing the laminated piezoelectric element 1 having 12 will be described.
[0019]
As shown in FIG. 2, this method includes a first unfired portion 21 for the first protective layer 11 in which a predetermined number of first unfired sheets 310 are laminated via an adhesive layer 35, and the first unfired portion 21. On the other hand, a third unfired portion 23 in which a predetermined number of unfired piezoelectric layer sheets 332 provided with internal electrode layer printing portions 331 are laminated via an adhesive layer 35, and a second unfired portion 23 with respect to the third unfired portion 23. By firing the unfired laminated body 2 including the second unfired portion 22 for the second protective layer 12 in which a predetermined number of unfired sheets 320 are laminated via the adhesive layer 35, the multilayer piezoelectric element 1 is obtained. It is a manufacturing method.
[0020]
A method for obtaining the unfired laminate 2 will be briefly described.
As shown in FIGS. 2 to 8, the first and second unbaked sheets 310 and 320 and the unbaked sheet 332 for the piezoelectric layer can be collected so that at least one stacked piezoelectric element 1 can be produced. A large green sheet 30 having a size is prepared.
An internal electrode layer printing portion 331 is formed by printing on a portion of the large green sheet 30 that will be the piezoelectric layer green sheet 332, and the large green sheet 30 includes first and second green sheets 310 and 320, piezoelectric elements. The adhesive layer 35 is printed and formed on a portion that becomes the unfired sheet 332 for layers.
[0021]
Then, the first green sheet 310 is punched from the large green sheet 30 and simultaneously laminated and pressed to form the first green section 21, and the piezoelectric layer green sheet 332 is punched and simultaneously stacked and pressed. A third unfired portion 23 is formed by laminating the first unfired portion 21, and a second unfired sheet 320 is punched out and simultaneously laminated and laminated on the third unfired portion 23. The unburned part 22 is formed.
Thereby, the unfired laminated body 2 which consists of the 1st unburned part 21, the 3rd unburned part 23, and the 2nd unburned part 22 concerning FIG. 2 is obtained.
[0022]
This will be described in detail below.
As shown in FIG. 1, the multilayer piezoelectric element 1 according to this example has a drive layer 13 between a first protective layer 11 and a second protective layer 12, and the drive layer 13 is a piezoelectric layer 132. The first and second protective layers 11 and 12 have a structure in which ceramic layers 110 and 120 having the same composition as the piezoelectric layer 132 are stacked.
[0023]
The internal electrode layer 131 in the drive layer 13 is a partial electrode that covers a part of the surface of the piezoelectric layer 132, and the end surface 135 of the internal electrode layer 131 is one layer of the piezoelectric layer 132 with respect to the side surfaces 101 and 102 of the multilayer piezoelectric element 1. Every other exposure.
The side surface electrodes 14 are provided on the side surfaces 101 and 102 of the multilayer piezoelectric element 1, and the end surface 135 of the internal electrode layer 131 exposed at each side surface 101 and 102 is electrically connected by the side surface electrode 14.
The side electrode 14 is connected to the lead terminal 141 by the conductive paste 140, and the lead terminal 141 is connected to an external power source (not shown).
[0024]
The piezoelectric layer 132, the first and second protective layers 11 and 12 of the driving layer 13 are made of PZT, and the internal electrode layer 131 is made of Pt · Ag. Further, as described below, in the state of the unfired laminated body, the ceramic layers 110 and 120 constituting the piezoelectric layer 132 and the first and second protective layers 11 and 12 are all adhered by the adhesive layer 35. However, since the adhesive layer 35 has the same composition as the piezoelectric layer 132 and the ceramic layers 110 and 120, it is substantially integrated with the piezoelectric layer 132 and the ceramic layers 110 and 120 after firing. Therefore, it is omitted in the description of FIG.
[0025]
In addition, the drive layer 13 and the first and second protective layers 11 and 12 of this example are stacked in the number of the drive layer 13 with the piezoelectric layer 132 being 100 μm (before firing), and the first and second protective layers. The layers 11 and 12 were formed by laminating 5 ceramic layers 110 and 120 each at 100 μm (before firing). In the drawing, the number of stacked sheets is described with a low priority in view of easy viewing.
[0026]
Next, details of the manufacturing method of this example will be described.
As shown in FIG. 3A, a large green sheet 30 is prepared.
1000 g of a ceramic material made of PZT and having an average particle size of 0.5 μm is prepared.
To this, 40 g of a binder made of PVB (polyvinyl butyral) and an appropriate amount of solvent are added to obtain a slurry. The slurry is formed by a doctor blade method to obtain a large green sheet 30 having a thickness of 100 μm.
The large unfired sheet 30 has a width that allows several piezoelectric layers 132 or the like to be collected, and the longitudinal direction includes the piezoelectric layers 132 or the like corresponding to several to several tens of unfired features 2 of this example. The length should be sufficient for collection.
[0027]
Next, as shown in FIG. 3B and FIG. 4, an internal electrode layer printing section 331 having a thickness of 6 μm is provided on the large green sheet 30.
The internal electrode layer printing section 331 is prepared by preparing 1000 g of an electrode material having an average particle size of 0.5 μm made of Pd and Ag, and adding 40 g of a binder made of PVB (polyvinyl butyral) and an appropriate amount of a solvent. Form a slurry for internal electrode layers using screen printing.
[0028]
Screen printing will be described.
As shown in FIG. 5, a carrier film 45 is arranged on a conveying device 49 in which a guide 42 is arranged between two rollers 41 and 43. On the carrier film 45, a printing mask 4 on which slurry for internal electrode layers is deposited is disposed. The printing mask 4 includes a frame body 40 and a screen 41 stretched in the frame body 40, and the screen 41 has printing holes 402 for dropping slurry into the shape of the internal electrode layer printing section 331.
Then, the slurry is dropped from the printing mask 4 onto the large green sheet 30 disposed on the carrier film 45 to form a large number of internal electrode layer printing portions 331 having a predetermined shape.
[0029]
Further, instead of screen printing, the printing section can be formed by the following method.
As shown in FIG. 6, a carrier film 45 is arranged on a conveying device 49 in which a guide 42 is arranged between the two rollers 41 and 43. A jet nozzle 46 capable of ejecting the slurry for the internal electrode layer is installed on the carrier film 45, and the slurry for the internal electrode layer is injected from the jet nozzle 46 onto the large green sheet 30 disposed on the carrier film 45. A large number of internal electrode layer printing portions 331 having a predetermined shape are formed.
[0030]
By the way, how to use the large green sheet 30 will be described with reference to FIG. First, the large green sheet 30 has the following areas.
That is, the first protective layer region 301 is a place where the first green sheet 310 for the ceramic layer 110 to be the first protective layer 11 is collected, and the second protective layer region 302 is the ceramic layer 120 to be the second protective layer 12. It becomes a collection place of the second green sheet 320 for use.
The drive layer region 303 is a portion for collecting the piezoelectric layer green sheet 332 to be the drive layer 13, and the internal electrode layer 131 exists only in the drive layer 13, so the internal electrode layer printing unit 331 is used for the drive layer. It is provided only in the area 303.
[0031]
In this way, the large green sheet 30 can be divided into a first protective layer collection region 301, a drive layer collection region 303, and a second protective layer collection region 302. A region 300 obtained by combining these three regions is a place to obtain the first and second green sheets 310 and 320 and the piezoelectric layer green sheet 332 corresponding to one of the multilayer piezoelectric elements 1.
[0032]
In the manufacturing method of this example, as shown as row A in FIG. 4, a large number of regions 300 related to one laminated piezoelectric element 1 are secured in a row along the longitudinal direction of the large green sheet 30.
And the said area | region 300 is arranged and secured by aligning the position in the width direction of the large unbaked sheet 30.
[0033]
Each region is described in the explanation, and when the actual green laminate 2 is manufactured, the first green sheet 310, the piezoelectric layer green sheet 332, and the second green sheet 320 surrounded by a dotted line are used. Only this part is punched out.
[0034]
Next, as shown in FIG. 3C, an adhesive layer 35 having a thickness of 11 μm is provided on the large green sheet 30 provided with the internal electrode layer printing portion 331.
The slurry for the adhesive layer is prepared by preparing 100 g of a ceramic material having an average particle size of 0.6 μm made of PZT (the same material as that used for the large unfired sheet) and adding 12 g of a binder made of PVB thereto. .
[0035]
The adhesive layer slurry is printed on the large green sheet 30 in the same manner as the method shown in FIGS. The adhesive layer 35 has the same size and shape as the first green sheet 310, the piezoelectric layer green sheet 332, and the second green sheet 320. Alternatively, the adhesive layer 35 can be provided so as to cover the whole of the plurality of internal electrode layer printing portions.
[0036]
Next, the first and second green sheets 310 and 320 and the piezoelectric layer green sheet 332 are punched from the large green sheet 30 and laminated simultaneously with the punching to obtain the green laminate 2. FIG. 3D shows the first and second green sheets 310 and 320 and the piezoelectric layer green sheet 332 in the punched state. In the manufacturing method of this example, lamination is performed at the same time as punching, so that each unsintered sheet does not become a single state as shown in FIG.
[0037]
The punching and laminating were performed using a punching and laminating apparatus 6 as shown in FIGS.
The apparatus 6 stacks a punch 61 for punching a large unfired sheet 30, and first and second unfired sheets 310 and 320 punched by the punch 61 and an unfired sheet 332 for a piezoelectric layer, and in the middle of the stacking. A holder 64 for supporting the unfired laminated body 2, and includes a lower mold 62 disposed on the lower side of the large unfired sheet 30 and a die mold 63 disposed on the upper side.
[0038]
The punch 61 has a configuration including a plurality of punch portions 619 connected by a support portion 610 in order to punch out the plurality of first unfired sheets 310 and the like simultaneously in the width direction of the large unfired sheet 30.
The holder 64 also includes a plurality of holder parts 641 connected by the support part 640. As shown in FIG. 8, the holder portion 641 includes a concave portion 642 that supports the unfired laminate 2 and an air hole 643 that communicates with the concave portion 642.
[0039]
A pump (not shown) sucks the inside of the concave portion 642 through the air hole 643 of the holder portion 641, and this suction force fixes the unfired laminated body 2 to the holder portion 641.
Further, as shown in FIG. 2 and FIG. 8, the unfired laminate 2 can be easily detached from the holder portion 641 between the uppermost surface 209 of the unfired laminate 2 and the ceiling surface 644 of the concave portion 642. A dummy sheet 29 is provided as described above.
Since the uppermost surface 209 of the unfired laminated body 2 becomes the adhesive layer 35 as shown in FIG. 2, if the dummy sheet 29 is not provided, the unfired laminated body 2 is strongly bonded to the holder portion 641 and may not come off. is there.
[0040]
The lower mold 62 includes a guide hole 620 through which the tip of the punch portion 619 passes. In addition, the die 63 is also provided with a guide hole 630. In a state where the large green sheet 30 is sandwiched between the lower mold 62 and the die mold 63, the first and second green sheets 310 and 320 and the piezoelectric layer green sheet 332 are punched out by the punch portion 619. It is.
[0041]
The punching lamination using the apparatus 6 will be described.
That is, the large green sheet 30 is introduced between the lower mold 62 and the die mold 63 of the punching and laminating apparatus 6.
In this state, the punch unit 619 is moved from the lower side to the upper side in the drawing, and the first and second green sheets 310 and 320 and the piezoelectric layer green sheet 332 are punched from the large green sheet 30.
[0042]
As shown in FIG. 7, the large unbaked sheet 30 provided with the inner electrode layer printing part 331 and the adhesive layer 35 in a predetermined place is peeled off from the carrier film 45 in the roller 450, while the lower die 62 of the punching and laminating apparatus 6 is It sent out between the die type | molds 63.
And the dummy sheet | seat 29 is set here, attracting | sucking the inside of the recessed part 642 with the pump which abbreviate | omitted illustration. Note that the dummy sheet 29 can be mounted by a collet method. Either adsorption or collet method is suitable for mass production.
Then, punching and laminating are sequentially performed from a portion of the large unfired sheet 30 on the first protective layer sampling region 301.
The punched first green sheet 310 passes through the guide hole 630 and comes into pressure contact with the dummy sheet 29 of the holder 64, and continues to the other first green sheet 310, the piezoelectric layer green sheet 332, and finally the first sheet. Two unfired sheets 320 are laminated in a predetermined number of times. In this way, the green laminate 2 is formed on the holder 64.
In addition, the pressure at the time of this lamination | stacking crimping | combination will be about 0.02-0.1 MPa.
[0044]
The remnants of the large unfired sheet 30 remaining after the punching are collected by a winder 48.
In FIG. 6, the hatched portions are the first and second green sheets 310 and 320 and the piezoelectric layer green sheet 332 to be punched. The white spot on the right side of the drawing from the punching device 6 is a mark after the punching is finished.
[0045]
The unfired laminated body 2 that has been laminated can be removed by stopping and opening the pump that sucks the concave portion 642 of the holder portion 641.
After removing the unfired laminate 2, the large unfired sheet 30 is stopped at one end, and the dummy sheet 29 is set on the holder portion 641 again. Then, the large unsintered sheet 30 is sent out again, and the next unsintered laminate 2 is continuously manufactured by sequentially punching and stacking again from the portion related to the next sampling region 301 for the first protective layer.
[0046]
And the obtained unbaked laminated body 2 was heated for removing the binder, and then kept at a temperature of 1000 ° C. for 2 hours and fired. Since the dummy sheet 29 is made of a material that is burned off during firing, it does not remain later.
And the side surface electrode 14, the lead part 141, etc. were attached, and the laminated piezoelectric element 1 concerning this example was obtained.
[0047]
Although each part of the multilayer piezoelectric element 1 obtained by the above method was observed, neither delamination nor cracks occurred.
Further, by the same manufacturing method as described above, 250 piezoelectric layers 132 of the drive layer 13 are stacked, and the first and second protective layers 11 and 12 are stacked by 10 ceramic layers 110 and 120, respectively, to form a stacked piezoelectric body. Element 1 was produced.
Neither delamination nor cracks occurred in this device.
[0048]
The effect concerning this example is demonstrated.
In the manufacturing method of this example, the first and second protective layers 11 and 12 and the first and second unfired sheets 310 and 320 to be the drive layer 13 are fired to form one unfired sheet 332 for the piezoelectric layer. The large unbaked sheet 30 is collected. Since it is collected from the same sheet, there is little difference in material and properties, and it is difficult for a difference in firing shrinkage between the portion applied to the protective layers 11 and 12 and the portion applied to the drive layer 13 at the time of firing. Lamination etc. can be prevented and the strength is unlikely to decrease.
[0049]
In addition, since the first and second green sheets 310 and 320 and the piezoelectric layer green sheet 332 are bonded using the adhesive layer 35, the pressure applied when these green sheets are laminated and pressed can be lowered. it can.
When the bonding pressure is high, defects or the like occur in the unfired sheet, causing microcracks after firing. By using this example that can be bonded at a low pressure, the above problem can be prevented.
[0050]
In the manufacturing method according to this example, the first and second green sheets 310 and 320 and the piezoelectric layer green sheet 332 are punched from the large green sheet 30 and stacked at the same time to form the green laminate 2. To do. Therefore, it is not necessary to perform the process of collecting from a large green sheet and the process of laminating separately, so that the production efficiency is increased and the production speed is also improved. Therefore, the manufacturing cost is also low.
Furthermore, since the first and second protective layers 11 and 12 are made of the same material as the piezoelectric layer 132 and the expensive material such as the internal electrode layer 131 is not included in the first and second protective layers 11 and 12, Raw material costs are reduced.
[0051]
As described above, according to this example, it is possible to obtain a method for manufacturing a multilayer piezoelectric element having few defects such as cracks and delamination, excellent durability, excellent production efficiency, and low cost.
In this example, the large green sheet 30 is punched from the bottom to the top, but conversely, it can be stacked by punching from the top to the bottom.
[0052]
(Comparative example)
As shown in FIG. 9, the multilayer piezoelectric element 9 was produced as follows.
The drive unit 13 is produced in the same manner as in this example, but the first and second protective layers 91 and 92 are made of slurry from PZT used for producing the piezoelectric layer 132, and this is injection-molded to obtain a predetermined one. The size and shape of the green body were used. The green body is joined to the drive unit in a state where the green sheets before baking are laminated and joined by (1) an adhesive layer (using the same material as in the example) to obtain a green laminate.
Alternatively, the drive unit and the unfired body are incorporated in a pressure jig. (2) After pressurizing at 80 ° C. for 30 minutes, the pressure is set to 30 MPa, and pressure bonding is performed for 1 minute to obtain an unfired laminate.
[0053]
When the unfired laminate obtained by the above (1) and (2) was fired under the same conditions as in the example, (1) had a problem that a crack was generated between the protective layer and the driving layer, causing peeling. It was.
In (2), since the heat and pressure bonding is performed with a high pressure, the density varies. Therefore, if the shrinkage at the time of firing is not uniform, cracks occur and the problem of peeling occurs.
[Brief description of the drawings]
FIG. 1 is an explanatory cross-sectional view of a multilayer piezoelectric element in an example.
FIG. 2 is a cross-sectional explanatory view of an unfired laminated body in an example.
FIG. 3 is an explanatory diagram of a process for forming an internal electrode layer printing portion and an adhesive layer on a large unfired sheet in an example.
FIG. 4 is an explanatory plan view showing a state in which the internal electrode layer printing portion is formed on the large green sheet in the embodiment.
FIG. 5 is an explanatory diagram of formation of a printing part for internal electrode layers by screen printing in an example.
FIG. 6 is an explanatory diagram of formation of a printing part for internal electrode layers by jetting from a nozzle in an example.
FIG. 7 is an explanatory diagram of punching lamination in an example.
FIG. 8 is an explanatory view of a main part of punching lamination in an example.
FIG. 9 is a cross-sectional explanatory view of a multilayer piezoelectric element in a comparative example.
[Explanation of symbols]
1. . . Laminated piezoelectric element,
11. . . A first protective layer,
12 . . A second protective layer,
13. . . Driving layer,
131. . . Internal electrode layer,
132. . . Piezoelectric layer,
2. . . Unfired laminate,
21. . . 1st unbaked part,
22. . . Second unbaked part,
23. . . Third unburned part,
30. . . Large green sheet,
310. . . First green sheet,
320. . . Second green sheet,
331. . . Unfired part for internal electrode layer,
332. . . Green sheet for piezoelectric layer,
35. . . Adhesive layer,

Claims (1)

A laminated piezoelectric element comprising a driving layer in which piezoelectric layers and internal electrode layers are alternately laminated, and first and second protective layers on both end surfaces in the laminating direction of the driving layer;
A first first green portion of the protective layer of the first unsintered sheet are layered with a prescribed number of adhesive layers, provided the printing portion internal electrode layer with respect to green portion of the first stacked through a third green part the green sheet for a piezoelectric layer laminated through a predetermined number adhesive layer, the predetermined number adhesive layer and a second green sheet to green part of the third a method of manufacturing by firing become more green laminate and the second of the second green portion of the protective layer, and
In obtaining the unfired laminate,
Prepare at least stacked aliquot capable piezoelectric element to one producing the first and second green sheet, a large green sheet having a size capable of collecting green sheet for a piezoelectric layer,
The printing portion internal electrode layer formed by printing on the portion to be a green sheet for a piezoelectric layer in the large green sheet, the first and second green sheet in the large green sheet, the green sheet for a piezoelectric layer An adhesive layer is printed on
Next, the first unfired sheet is punched from the large unfired sheet, and at the same time, a predetermined number of sheets are stacked and pressure-bonded to form the first unfired portion, and then the piezoelectric layer unfired sheet is simultaneously punched out the laminated crimped to the first green part to form a third green part, further followed by the second green sheet punched out at the same time a predetermined number of sheets stacked crimped to the third green part A method for manufacturing a laminated piezoelectric element, characterized in that a second unfired part is formed.

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