JP2003174206A - Stacked piezoelectric element - Google Patents

Abstract

(57) [Problem] To provide a low-cost multilayer piezoelectric element in which peeling of a piezoelectric layer and an internal electrode layer hardly occurs, electrical conduction between a side electrode and an internal electrode layer can be reliably ensured, and the cost is low. Trying to provide. SOLUTION: A plurality of piezoelectric layers 11 and 12 which expand according to an applied voltage, and internal electrode layers 13 and 14 for supplying an applied voltage.
And a pair of side electrodes provided on the side surfaces 101 and 102 of the piezoelectric stack 10 so as to be electrically connected to the internal electrode layers 13 and 14 alternately. Are the extraction electrode layers 132 and 142
And the joining electrode layers 131 and 141. The extraction electrode layers 131 and 141 have high conductivity and ensure conductivity with the side electrodes, and the joining electrode layers 132 and 142 are connected to the piezoelectric layers 11 and 12. Ensure bonding.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a laminated piezoelectric element that expands and contracts in the laminating direction when an electric current is applied.

[0002]

2. Description of the Related Art The following structure is well known as a laminated piezoelectric element. As shown in FIGS. 13 to 15, the laminated piezoelectric element 8 includes a piezoelectric stack 80 in which internal electrode layers 83 and 84 are alternately formed between the piezoelectric layers 81 and 82 so that positive and negative voltages can be applied. , The piezoelectric stack 80
On the side surfaces 801 and 802 of the inner electrode layers 83 and 84.
And a pair of side surface electrodes 851 provided to ensure electrical continuity with
And 852. Dummy layers 18 and 19 are provided at both ends of the piezoelectric layers 81 and 82 in the stacking direction.

In the piezoelectric stack 80, as shown in FIGS.
As shown in FIG. 5, one internal electrode layer 83 has one side surface 8
01, and the other internal electrode layer 84 is exposed to the other side surface 80.
Exposed to 2. Side surfaces 801, 802 of the piezoelectric stack 80
At this point, side surface electrodes 851 and 852 are formed which are electrically connected to the exposed ends of the internal electrode layers 83 and 84. The piezoelectric element 8
Are formed by forming printed portions for the internal electrode layers 83 and 84 on the green sheets for the piezoelectric layers 81 and 82, alternately stacking them, and then pressure-molding, drying, firing, and machining the side surface electrodes 85.
1, 852 are provided and created.

[0004]

In recent years, it has been considered to use a laminated piezoelectric element as a drive source for a fuel injection injector of an automobile or the like. When used as an injector, high performance is required to obtain large displacement even when the voltage applied to the piezoelectric layer is low. Therefore, a very large number of piezoelectric layers may be laminated to form a piezoelectric element. In addition, the piezoelectric element must have high reliability, and we want to prevent cracks from occurring due to the stress that occurs when a voltage is applied.

In the piezoelectric element 8 according to FIGS. 13 to 15 described above, the internal electrode layer 83 is electrically connected to the side surface electrode 851, the internal electrode layer 84 is electrically connected to the side surface electrode 852, and the internal electrode layer 83 is connected to the side surface. It is desired that the electrode 852 be insulated and the internal electrode layer 84 be insulated from the side surface electrode 851. Therefore, the internal electrode layers 83 and 84 are formed to be slightly smaller than the outer circumferences of the piezoelectric layers 81 and 82, which is apparent from FIG. That is, there are non-formation portions 810 and 820 of the internal electrode layers 83 and 84 on the surfaces of the piezoelectric layers 81 and 82.

Therefore, as is clear from FIG. 15 and the like,
The piezoelectric layers 81 and 82 are applied with a voltage only to a portion 800 sandwiched by the internal electrode layers 83 and 84. Therefore, the peripheral portion of the piezoelectric element 8 becomes relatively inactive. The inactive part suppresses the generation of strain and causes a large amount of stress. Then, the stress may cause cracks or breaks in the piezoelectric element 8.

In order to prevent the above-mentioned problems, as shown in FIG. 16, a piezoelectric element 9 having an internal electrode layer 93 having the same area as that of the piezoelectric layer 91 and having a full-surface electrode structure having no non-formed portion is provided.
Can be considered. However, in the whole-surface electrode structure, the contact area between the piezoelectric layer 91 and the internal electrode layer 93 becomes wider. Further, since the piezoelectric layer 91 and the internal electrode layer 93 have different compositions, peeling and firing distortion are likely to occur. Further, in the case of a full-surface electrode structure, more electrode material is required, so the cost tends to increase.

Further, in order to secure the bondability with the piezoelectric layer, the internal electrode layer is mixed with a ceramic material having a composition similar to or the same as that of the piezoelectric layer in order to secure the bondability with the piezoelectric layer in both the case of the whole surface electrode structure and the case of the partial electrode structure. However, there is also a problem in that it is difficult to secure electrical continuity between the portion exposed on the side surface of the piezoelectric stack and the side surface electrode because the conductivity decreases as much as the ceramic material is mixed.

The present invention has been made in view of the above-mentioned conventional problems. It is difficult for the piezoelectric layer and the internal electrode layer to be separated from each other, and the electrical conduction between the side surface electrode and the internal electrode layer is surely secured. It is an object of the present invention to provide a laminated piezoelectric element that is possible and inexpensive.

[0010]

A first invention is a piezoelectric stack in which a plurality of piezoelectric layers extending in response to an applied voltage and an internal electrode layer for supplying an applied voltage are alternately laminated, and the internal portion is provided on a side surface of the piezoelectric stack. The internal electrode layer is composed of a pair of side surface electrodes provided so as to be electrically connected to every other electrode layer, the internal electrode layer is composed of an extraction electrode layer and a bonding electrode layer, and the extraction electrode layer has high conductivity and the side surface electrodes. And the bonding electrode layer secures the bonding property with the piezoelectric layer (claim 1).

Next, the function and effect of the present invention will be described.
A part of the internal electrode layer is a bonding electrode layer that secures the bonding property with the piezoelectric layer, and the other part is an extraction electrode that secures the conductivity with the side surface electrode. The bonding electrode layer strongly adheres the piezoelectric layers to each other, and peeling is less likely to occur. Further, the extraction electrode layer can secure the electrical continuity between the extraction electrode layer and the side surface electrode, and the contact resistance between the extraction electrode layer and the side surface electrode can be reduced. The present invention is particularly effective when the internal electrode layer is thin.

The internal electrode layer is generally formed by mixing another material with the electrode material. The bonding electrode layer has a conductivity that prevents peeling from the piezoelectric layer and can apply a voltage to the piezoelectric layer. Therefore, it is possible to form the bonding electrode layer with a smaller amount of electrode material than the conventional one. Since an expensive noble metal is generally used as the electrode material, the present invention can reduce the cost of the piezoelectric element.

As described above, according to the present invention, peeling between the piezoelectric layer and the internal electrode layer is unlikely to occur, and electrical conduction between the side surface electrode and the internal electrode layer can be reliably ensured, and the cost is low. Body elements can be provided.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The piezoelectric layer according to the first invention (claim 1) is made of a material having a piezoelectric effect. For example, PZT (lead zirconate titanate), a material obtained by adding another element to PZT, barium titanate, and other ceramics having a piezoelectric effect. The thickness of the piezoelectric layer is, for example, 5
It is set to 0 to 150 μm. Each of the joining electrode layer and the extraction electrode layer forming the internal electrode layer is made of a material containing a conductive material. The conductive material is specifically palladium,
Gold, platinum, silver, copper, etc., or alloys of these metals are often used.

Further, the bonding electrode layer has such a conductivity that the piezoelectric layer can be expanded and contracted by applying a voltage from the side surface electrode through the extraction electrode layer. In addition, at the location where the extraction electrode layer is exposed on the side surface of the piezoelectric stack,
Since it is configured to be electrically connected to the side electrode,
The electrical resistance is low and the contact resistance with the side electrodes is low. Further, the internal electrode layer may have a partial electrode structure or a full-surface electrode structure with respect to the piezoelectric layer.

Further, as shown in FIGS. 9 and 10 which will be described later, the lead-out electrode layer may be shaped so as to be fitted toward the center of the internal electrode layer. In particular, when the area of the internal electrode layer is larger than that of the extraction electrode, the electrical resistance of the bonding electrode layer becomes high, and the potential of the bonding electrode layer may not be high enough to apply a sufficient voltage to the piezoelectric layer. In such a case, the electric potential of the internal electrode layer can be increased by inserting and forming the extraction electrode layer having higher conductivity inside.

Further, it is preferable that the bonding electrode layer occupies 80 to 99% of the surface area of the internal electrode layer (claim 2). In this case, it is possible to reliably prevent the piezoelectric layer and the internal electrode layer from peeling off, and to ensure reliable conduction with the side surface electrode.

If the ratio of the surface area of the bonding electrode layer to the surface area of the internal electrode layer is less than 80%, the area of the bonding electrode layer is small and the bonding property with the piezoelectric layer may be weakened. Further, since the ratio of the extraction electrode layer containing abundantly expensive electrode material is high, the material cost may be high. Also, when the bonding electrode layer exceeds 99%,
Since the extraction electrode layer is narrowed, there is a possibility that the extraction electrode layer cannot be partially taken out due to misalignment at the time of stacking or firing strain. The surface area of the internal electrode layer is the area of the surface facing the piezoelectric layer.

It is preferable that the bonding electrode layer contains 10 to 50% by weight of a ceramic material (claim 3). Since the physical properties of ceramic materials are similar to those of piezoelectric layers,
The physical properties such as the contraction rate and the thermal expansion rate of the bonding electrode layer can be made closer to those of the piezoelectric layer. Therefore, peeling between the bonding electrode layer and the piezoelectric layer is less likely to occur, and the bonding strength between the two can be increased.

If the amount of the ceramic material is less than 10% by weight, the above-mentioned effects may not be realized due to lack of the ceramic material. On the other hand, if it exceeds 50% by weight, the resistance of the bonding electrode layer becomes too large and the role of applying a voltage to the piezoelectric layer may not be fulfilled (see FIGS. 11 and 12).

Further, it is preferable that the raw material powder of the bonding electrode layer has a larger average particle size than the raw material powder of the piezoelectric layer (claim 4). In the piezoelectric element, the green powder made from the raw material powder of the piezoelectric layer is used to paste the raw material powder of the bonding electrode layer and the extraction electrode layer into a desired shape, and the resulting sheet is laminated, pressure-bonded, and fired. It is produced by By defining the average particle size of the raw material powder used at this time as described above, the particles easily bite (anchor effect), and the bondability between the bonding electrode layer and the piezoelectric layer can be enhanced.

The average particle size of the raw material powder for the bonding electrode layer is preferably 1 to 5 μm (claim 5). This makes it easier for the particles to bite (anchor effect), so that the bondability between the bonding electrode layer and the piezoelectric layer can be improved. If the average particle size is smaller than 1 μm, the bite may be weak, and if it is larger than 5 μm,
On the contrary, the particle size may become too large and the bite may be weakened.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. (Example 1) A piezoelectric element according to the present invention and a method for manufacturing the same will be described below. As shown in FIGS. 1 to 3,
The piezoelectric element 1 according to the present example includes a piezoelectric stack 10 in which a plurality of piezoelectric layers 11 and 12 that expand according to an applied voltage and internal electrode layers 13 and 14 for supplying an applied voltage are alternately laminated.
And a pair of side surface electrodes 151, 152 provided on the side surfaces 101, 102 of the piezoelectric stack 10 so as to be electrically connected to the internal electrode layers 13, 14 every other layer.

The internal electrode layers 13 and 14 are composed of extraction electrode layers 132 and 142 and bonding electrode layers 131 and 141, and the extraction electrode layers 132 and 142 have high conductivity and are connected to the side surface electrodes 151 and 152. The conductivity is secured, and the bonding electrode layers 131 and 141 secure the bonding property with the piezoelectric layers 11 and 12.

A detailed description will be given below. As shown in FIG. 1, the laminated piezoelectric element 1 includes a piezoelectric stack 10 in which internal electrode layers 13 and 14 are alternately formed between layers of piezoelectric layers 11 and 12 so that positive and negative voltages can be applied thereto. A pair of side surface electrodes 1 provided on the side surfaces 101 and 102 of the stack 10.
It consists of 51 and 152.

In the piezoelectric stack 10, the internal electrode layer 1
3 is exposed on one side surface 101, and the internal electrode layer 14 is exposed on the other side surface 102. Side surface 10 of piezoelectric stack 10
Side electrodes 151 and 152 are formed on the electrodes 1 and 102 so as to electrically connect the exposed end surfaces of the internal electrode layers 13 and 14, respectively. As shown in FIG. 3, the internal electrode layer 13 and the side surface electrode 151 are electrically connected to each other, and the internal electrode layer 14 and the side surface electrode 151 are connected to each other.
To prevent electrical continuity between the insulating part 150 and the side surface 1.
In 01, it is provided on the end face of the internal electrode layer 14. The same applies to the side surface electrode 152.

Further, the piezoelectric stack 10 of the internal electrode layer 13
The exposed portion on the side surface 101 of the extraction electrode layer 132 is formed. The extraction electrode layer 142 is also provided in the same position for the internal electrode layer 14. Then, as shown in FIG. 1, one of the piezoelectric layers 11 is formed so that both surfaces of the piezoelectric layer 11 have different polarities.
Is provided with an extraction electrode layer 132 on the right side of the drawing.
The lead-out electrode layer 142 is provided on the left side of the drawing for the piezoelectric layer 12 adjacent in the stacking direction. Then, the extraction electrode layers 132, 14
The portions other than 2 are the bonding electrode layers 131 and 141. The internal electrode layers 13 and 14 are the piezoelectric layers 11 and 12, respectively.
The same area, that is, the entire surface electrode configuration.

The piezoelectric layers 11 and 12 have a thickness of 100 μm.
The internal electrode layers 13 and 14 have a thickness of 5 μm. Figure 1
Although omitted, the piezoelectric stack 10 according to the present example has a total of 500 piezoelectric layers 11 and 12 laminated.

The piezoelectric layers 11 and 12 of this example are made of lead zirconate titanate, that is, PZT. The internal electrode layer 13,
14 contains as a co-material a ceramic material having the same composition as the electrode material composed of palladium and silver. This material is PZ
T. The bonding electrode layers 131 and 141 contain the electrode material made of palladium and silver in an amount of 50 to 80% by weight based on the total weight of the internal electrode layers 13.
The remainder of 41 is composed of components such as PVB (polyvinyl butyral) as a co-material and other resins, a solvent and the like. Further, the extraction electrode layers 132 and 142 are made of the above-mentioned electrode material of 80
-100% by weight, the above-mentioned co-materials, resins, solvents, etc. account for the rest.

A method of manufacturing the piezoelectric element 1 according to this example will be described. Powders of lead oxide, zirconium oxide, titanium oxide, niobium oxide, strontium carbonate and the like, which are the main raw materials of the piezoelectric layers 11 and 12, are weighed by a known method so as to have a desired composition. This is dry-mixed with a mixer and then calcined at 800 to 950 ° C.

Then, pure water and a dispersant are added to the calcined powder to form a slurry, which is wet-milled by a pearl mill. After drying and degreasing this crushed product, solvent, binder, plasticizer,
Add a dispersant and mix with a ball mill. afterwards,
Vacuum degassing and viscosity adjustment are performed while stirring this slurry in a vacuum device with a stirrer. Next, the slurry is formed into a sheet having a constant thickness by a doctor blade device, and
As shown in FIG. 4, the green sheet 50 having a larger area than the four piezoelectric layers is punched.

Next, two kinds of silver and palladium pastes (hereinafter referred to as Ag / Pd pastes) are prepared. One is for the bonding electrode layers 131 and 141, which uses an electrode material of silver 70 and palladium 30 (wt%).
It is a composition in which 40% (wt%) of the co-material is added to%.
The other is a composition for the extraction electrode layers 132 and 142, in which an electrode material of silver 70 and palladium 30 (wt%) is used, and 5% (wt%) of the common material is added to 95% of the electrode material.

As shown in FIG. 4, Ag / Pd for the extraction electrode layers 132 and 142 are provided at predetermined positions on the green sheet 50.
Screen printing the paste to print sections 532 and 54.
Form 2. Then, as shown in FIG. 5, Ag / Pd paste for the bonding electrode layers 131 and 141 is screen-printed at a predetermined position of the green sheet 50 to print the printed portion 531.
And 541 are formed. After that, the green sheet 50 is cut by punching with a press die, and the piezoelectric layers 11 and 12 are cut.
The sheets 51 and 52 for one sheet are created. In addition, two sheets having the same size as one of the piezoelectric layers 11 and 12 and not provided with the printing portion are prepared (not shown).

Next, these sheets 51 and 52 are attached to FIG.
Stacked to be a piezoelectric stack 10 as shown in
The printing portions 532 and 542 for the extraction electrode layers 132 and 142 are exposed on every other side of the sheets 51 and 52 on one side surface. In addition, a sheet having no printing portion is arranged at each of the upper end and the lower end of the piezoelectric stack 10 in the stacking direction.

Then, after thermocompression bonding with a hot water rubber press or the like, degreasing is performed in an electric furnace at 400 to 700 ° C., and 900 to
Bake at 1200 ° C. Then, the extraction electrode layers 132, 1
On the side surfaces 101 and 102 where 42 is exposed, insulating resin is applied to the portions where the bonding electrode layers 131 and 141 are exposed and dried to form the insulating portion 15. Then, silver plating,
Plate-shaped side surface electrodes 151 and 152 made of stainless steel are attached by adhesion with resin silver. From the above, the piezoelectric element 1
To get

The function and effect of this example will be described.
Part of the internal electrode layers 13 and 14 is the bonding electrode layers 131 and 141 that ensure the bondability with the piezoelectric layers 11 and 12, and the other part is the extraction electrode 151 that ensures the conductivity with the side surface electrodes 151 and 152. , 152. Bonding electrode layers 131, 14
1, the piezoelectric layers 11 and 12 are strongly adhered to each other, and peeling or the like in the piezoelectric stack 10 is less likely to occur. Further, the extraction electrode layers 132, 142 can secure the electrical continuity between the extraction electrode layers 132, 142 and the contact (electrical) resistance between the extraction electrode layers 132, 142 and the side electrodes.

The bonding electrode layers 131 and 141 are made of Ag /
The Pd paste is mixed with the materials for the piezoelectric layers 11 and 12. Therefore, the bonding electrode layers 131 and 141 and the piezoelectric layer 1
The shrinkage rate and the thermal expansion rate between 1 and 12 are close to each other, and isolation between the two can be prevented. Also, the bonding electrode layers 131, 1
Since the amount of Ag / Pd paste contained in 41 is smaller than the conventional amount, the cost of the piezoelectric element is reduced.

As described above, according to the present embodiment, the piezoelectric layer and the internal electrode layer are unlikely to be separated from each other, the electrical conduction between the side surface electrode and the internal electrode layer can be reliably ensured, and the cost is low. Body elements can be provided. As shown in FIGS. 7 and 8, the piezoelectric layer may have a barrel shape.

(Embodiment 2) In this embodiment, a fitting portion is provided in the extraction electrode layer toward the inside of the bonding electrode layer. As shown in FIG. 9, a wedge-shaped fitting portion 133 having a branch, FIG.
There is a fitting portion 133 that extends straight as shown in FIG.
The other configurations are the same as those in the first embodiment.

By providing the fitting portion 133, an electric path extending to the vicinity of the center of the internal electrode layer 13 can be formed. Since the bonding electrode layer 131 contains much of the same ceramic as that of the piezoelectric layer 11, the electrical resistance is high, and the voltage applied via the extraction electrode layer 132 does not fully spread to all the corners of the bonding electrode layer 131, and the potential is The voltage may be lowered, and it may be difficult to apply a voltage to the piezoelectric layer 11. By providing the fitting portion 133 as in this example, a high-potential portion centering on the fitting portion 133 is formed in the internal electrode layer 13, and a sufficient voltage can be applied to the piezoelectric layer 11. Other details are the same as in the first embodiment.

(Embodiment 3) In this embodiment, as shown in FIGS. 11 and 12, the relationship between the adhesion strength of the bonding electrode layer to the piezoelectric layer and the addition amount of the common material used as the ceramic material added to the bonding electrode layer. The relationship between the electrical resistance value per unit area of the bonding electrode layer and the additive amount of the common material was measured.

In the same laminated piezoelectric element as in Example 1, seven kinds of samples having different amounts of the common material added to the bonding electrode layer were prepared.
In addition, three elements were prepared for each sample.
Then, the adhesion strength between the bonding electrode layer and the piezoelectric layer in each sample was subjected to a tensile test using an Amsler tester, and the measurement results are shown in FIG. As is known from the figure, the adhesion strength increases as the amount of the co-material added to the bonding electrode layer increases, but it was found that the adhesion strength does not change much at 45 wt% or more even if the addition amount increases.

A measuring electrode made of baked silver
The side of the sample is provided on the side where the + -electrode is not taken out (the part where the internal electrode layer is not exposed), and the range is 10
It is appropriately selected between 50 layers. In this example, 20 layers are provided. This is because if there is only one layer, it will be difficult to connect the measurement terminal to the measurement electrode. Then, the electrical resistance value of the bonding electrode layer was measured by the voltage drop method in order to cancel the contact resistance.
The resistance value thus measured was multiplied by 20, converted into a value per layer, and further converted into a value per unit area, and described in FIG.

The unit "Ω / □" on the vertical axis of FIG. 12 represents a value obtained by dividing the electric resistance value of the entire bonding electrode layer (the value obtained by the above-mentioned measurement) by the area of the bonding electrode layer. The vertical axis of FIG. 12 is a logarithmic scale. From the figure, the addition amount of co-material is 50
It is clear that the electric resistance value sharply increases from the vicinity of exceeding the weight percentage.

When the electric resistance value of the junction electrode layer becomes higher than the boundary line M drawn in the center of the figure, it becomes difficult for current to flow, and it becomes difficult to apply a sufficient voltage to the piezoelectric layer. It was

From the above, by adding 10% by weight or more and less than 50% by weight of the co-material to the bonding electrode layer,
It was found that excellent adhesion with the piezoelectric layer was obtained. In particular, it was found that high adhesion can be obtained by adding 35% by weight or more of the co-material.

[0047]

[Brief description of drawings]

FIG. 1 is a perspective development view of a piezoelectric stack according to a first embodiment.

FIG. 2 is an explanatory cross-sectional view of a piezoelectric layer and an internal electrode layer in Example 1.

FIG. 3 is a perspective view of a piezoelectric element according to the first embodiment.

FIG. 4 is an explanatory diagram of a green sheet and a print portion for an extraction electrode layer according to the first embodiment.

FIG. 5 is an explanatory diagram of a green sheet and printed portions for a lead-out electrode layer and a bonding electrode layer in the first embodiment.

FIG. 6 is an explanatory diagram of a piezoelectric layer sheet according to the first embodiment.

FIG. 7 is a perspective development view of a piezoelectric stack having a barrel-shaped piezoelectric layer according to the first embodiment.

FIG. 8 is an explanatory perspective view of a barrel-shaped piezoelectric element according to the first embodiment.

FIG. 9 is an explanatory view for an extraction electrode layer having a branch-shaped fitting portion in the second embodiment.

FIG. 10 is an explanatory view for an extraction electrode layer having a straight fitting portion in the second embodiment.

FIG. 11 is a diagram showing the relationship between the adhesion strength of the bonding electrode layer to the piezoelectric layer and the additive amount of the common material in Example 3.

FIG. 12 is a graph showing the relationship between the electrical resistance value per unit area of the bonding electrode layer and the additive amount of the common material in Example 3.

FIG. 13 is a plan view of a conventional piezoelectric layer provided with a partial internal electrode layer.

FIG. 14 is a plan view of a conventional piezoelectric element having a partial internal electrode layer.

FIG. 15 is an explanatory diagram of a conventional piezoelectric element provided with a partial internal electrode layer.

FIG. 16 is a perspective development view of a conventional piezoelectric stack having an entire surface internal electrode layer.

[Explanation of symbols]

1. ． ． Piezoelectric element, 10. ． ． Piezoelectric stack, 11,12. ． ． Piezoelectric layer, 13, 14. ． ． Internal electrode layer, 131, 141. ． ． Junction electrode layer, 132, 142. ． ． Extraction electrode layer,

Claims (5)

[Claims] 1. A piezoelectric stack in which a plurality of piezoelectric layers that expand in response to an applied voltage and internal electrode layers for supplying an applied voltage are alternately laminated, and a conductive layer is alternately provided on the side surface of the piezoelectric stack. And a pair of side surface electrodes provided so that the internal electrode layer includes an extraction electrode layer and a bonding electrode layer, and the extraction electrode layer has high conductivity and secures conductivity with the side surface electrode. The laminated piezoelectric element characterized in that the bonding electrode layer secures the bonding property with the piezoelectric layer. 2. The laminated piezoelectric element according to claim 1, wherein the bonding electrode layer occupies 80 to 99% of the surface area of the internal electrode layer. 3. The multilayer piezoelectric element according to claim 1, wherein the bonding electrode layer contains 10 to 50% by weight of a ceramic material. 4. The method according to claim 1, wherein
The laminated piezoelectric element, wherein the raw material powder for the bonding electrode layer has a larger average particle diameter than the raw material powder for the piezoelectric layer. 5. The multilayer piezoelectric element according to claim 4, wherein the raw material powder for the bonding electrode layer has an average particle size of 1 to 5 μm.