CN101593808B - Multi-layer piezoelectric element and method for manufacturing the same - Google Patents

Abstract

A multi-layer piezoelectric element comprises a stack having an active portion constituted from at least one piezoelectric layer and a plurality of internal electrodes consisting of first and second internal electrodes placed one on another, the active portion being subjected to expansion and contraction in response to a voltage applied across the first internal electrode and the second internal electrode, and external electrodes formed on two side faces of the stack with one thereof being connected to the first internal electrode and the other connected to the second internal electrode, wherein each of the external electrodes is constituted from three or more layers including a first layer formed in contact with the side face of the stack and a second layer formed on the first layer, to provide a multi-layer piezoelectric element having high durability.

Description

Laminate type piezoelectric element and manufacture method thereof

Technical field

The present invention relates to laminate type piezoelectric element (following also abbreviate as " element "), for example, relate to the fuel injection device of lift-launch in automobile engine, liquid injection apparatus such as ink-jet, driving element in the precision positioning device of Optical devices etc. or the anti-locking apparatus of vibration etc., lift-launch is at combustion pressure sensor, seismological sensor, acceleration transducer, load sensor, ultrasonic sensor, voltage sensitive sensor, sensor element in the yaw rate sensor etc., and carry at piezoelectric gyroscope, Piezoelectric switches, piezoelectric transformer, the laminate type piezoelectric element that uses on the circuit element in the piezoelectricity circuit breaker etc.

Background technology

In the past, as laminate type piezoelectric element, the known lamination-type piezo actuator that alternative stacked piezoelectrics and internal electrode are arranged.The lamination-type piezo actuator is categorized as two kinds of the stacked types of the internal electrode that burns till piezoelectric ceramic that type and alternative stacked be made of 1 piezoelectrics and plate body simultaneously, but for the consideration that helps the low pressure electrification, reduces manufacturing cost aspect, thin layerization and help durability, the lamination-type piezo actuator that burns till type simultaneously shows superiority.

Fig. 7 is the figure of disclosed laminate type piezoelectric element in the past in the expression patent documentation 1.This laminate type piezoelectric element is made of laminated body 20 and the outer electrode 54 that is formed on the mutual opposed a pair of side.Laminated body 20 alternative stacked have piezoelectrics 51 and the internal electrode 52 that constitutes it, and but, internal electrode 52 is not to be formed on the whole interarea of piezoelectrics 51, and becomes so-called localizing electrode structure.Internal electrode about the 52 phase strange land laminations of this localizing electrode's structure make internal electrode 52 expose every different laminated body 20 sides of a course.And, form outer electrode 54 on the mutual opposed a pair of side and the internal electrode 52 conductings ground that exposes every one deck of laminated body 20.

In addition, the both ends of the surface lamination has inert layer 104 on the stack direction of laminated body 20.This inert layer 62 is also referred to as protective layer, and this protective layer does not generally comprise electrode 51.But, in this formation, comprise sometimes when burning till, to produce between the part of interior electrode layer 52 and the inert layer 62 and shrink poor, and produce stress or generation crack.In order to prevent this situation, a kind of method is disclosed in the patent documentation 3, as shown in Figure 8,, prevent to produce the crack burning till the back at the identical electrode 61 of inert layer 62 superimposed layers and active layer 63.In addition, owing to comprise that the part of the interior electrode layer 52 that is connected with outer electrode is and the corresponding part of stretching of the voltage that adds, so be called active layer.

Such laminate type piezoelectric element is made by following method.At first, on the ceramic green sheet that comprises piezoelectrics 51 raw materials with the graphic printing internal electrode cream of the electrode structure that becomes regulation, making is made laminated body 20 by it is burnt till again by a plurality of lamination formed bodies that obtain of the raw chip laminating that will be coated with this internal electrode cream.Then, on a pair of side of laminated body 20, obtain laminate type piezoelectric element (for example, with reference to patent documentation 1) by burning till formation outer electrode 54.

In addition, adopt alloy silver-colored and palladium, and in order to burn till piezoelectrics 51 and internal electrode 52 simultaneously, the metal composition of internal electrode 52 is made as: silver-colored 70 quality %, palladium 30 quality % (for example, with reference to patent documentation 2) as internal electrode 52.

Like this, only do not adopt by the metal of silver form the internal electrode 52 that constitutes and adopt by the metal that contains silver-palladium alloy (containing palladium) forms the internal electrode 52 that constitutes be because: have only in silver-colored the composition not containing coloured, under the situation of giving potential difference between the opposed pair of internal electrodes 52, can produce that silver in this pair of internal electrodes 52 propagate to move along element surface to negative pole from positive pole is so-called silver-colored transport phenomena.Should the silver transport phenomena in the environment of high temperature, high humidity especially obvious.

Under laminate type piezoelectric element that will be in the past uses situation as piezo actuator, further utilize soft solder with lead fixed externally (not shown) on the electrode 54, drive by the current potential that externally adds regulation between the electrode 54.Especially, in recent years, small-sized laminate type piezoelectric element is because bigger displacement is guaranteed in requirement under bigger pressure, so need add higher electric field and its long-time continuous is driven.

Patent documentation 1: Japanese kokai publication sho 61-133715 communique

Patent documentation 2: Japan opens flat 1-130568 communique in fact

Patent documentation 3: Japanese kokai publication hei 9-270540 communique

But in laminate type piezoelectric element, as described above, active layer is scalable, and is formed on outer electrode, not flexible of inert layer around it, can produce following such problem thus.

At first, because active layer produces change in size repeatedly when driving, so between long-term under high electric field, the high pressure under the situation of Continuous Drive, can peel off between outer electrode and the piezoelectrics or outer electrode self generation be full of cracks, thereby externally the connecting portion of electrode and internal electrode generation contact is bad sometimes.In view of the above, can not give a part of piezoelectrics service voltage, if long-time the use, placement property can change, and produces spark and causes driving to stop.

In recent years, for small-sized laminate type piezoelectric element, in order to obtain bigger displacement, and add higher electric field, drive continuously between long-term, therefore, it is obvious that such problem can become.

In addition, at the inert layer shown in the patent documentation 3, though the contraction difference between active layer and the inert layer is relaxed, but at applying high voltage, under the situation that especially long-time continuous drives, can have problems on the durability in the interface generation crack of the electrode 61 that forms inert layer 62 with piezoelectric layer (active portion) 63.

Summary of the invention

For this reason, the present invention puts in view of the above-mentioned problems and makes, its purpose is to provide a kind of displacement that can increase piezo actuator under high voltage, high pressure, and, even the laminate type piezoelectric element of the superior durability that displacement also can not change during long-term Continuous Drive.

To achieve these goals, the 1st laminate type piezoelectric element of the present invention, it is characterized in that, have: laminated body, it has active portion, this active portion is that at least 1 piezoelectrics of alternative stacked form with a plurality of internal electrodes that are made of first internal electrode and second internal electrode, described active portion and corresponding the stretching of voltage that is added between described first internal electrode and described second internal electrode, and outer electrode, it is respectively formed on 2 sides of described laminated body, one of them is connected with described first internal electrode, wherein another is connected with described second internal electrode

Described each outer electrode is to comprise join the 1st layer of forming and be formed on the 1st layer the 2nd layer at the interior layer more than 3 layers of side with described laminated body.

In addition, the 1st laminate type piezoelectric element of the present invention is characterized in that having:

Laminated body, it has active portion and is positioned at the inert layer that the both ends of this active portion are made of piezoelectric respectively, described active portion is that at least 1 piezoelectrics of alternative stacked form with a plurality of internal electrodes that are made of first internal electrode and second internal electrode, described active portion and corresponding the stretching of voltage that is added between described first internal electrode and described second internal electrode

Outer electrode, it is respectively formed on 2 sides of described laminated body, and one of them is connected with described first internal electrode, wherein another is connected with described second internal electrode,

The inert layer of described laminated body comprises dispersed metal.

Further, the manufacture method of laminate type piezoelectric element of the present invention is characterized in that, comprising:

The both ends of the surface of the living laminated body that forms at alternative stacked piezoelectrics raw cook and conductor layer form piezoelectric material layer;

On described piezoelectric material layer, form metal level;

After the described living laminated body that has formed described piezoelectric material layer and described metal level is burnt till, remove described metal level.

(invention effect)

The 1st laminate type piezoelectric element of the present invention of Gou Chenging as described above, because described each outer electrode is to comprise and join the 1st layer of forming and be formed on the 1st layer the 2nd layer at the interior layer more than 3 layers of described laminated body side, so can utilize the interface of the layer more than 3 layers to block be full of cracks (stoping be full of cracks to expand upper strata or lower floor to), produce the be full of cracks that runs through outer electrode integral body and stop.

In view of the above, can prevent to produce the outer electrode be full of cracks,, can improve the durability of laminate type piezoelectric element even the situation bottom offset amount of Continuous Drive can not change yet between long-term because of the change in size of described laminated body.

In addition, the 1st laminate type piezoelectric element of the present invention, because the inert layer of described laminated body comprises dispersed metal, burn till the stress that between inert layer and active layer, produces when shrinking so can relax (homogenizing), under high voltage, high pressure, can increase the displacement of piezo actuator, and,, can improve the durability under high voltage and long-time continuous operating position even the situation bottom offset amount of Continuous Drive can not change yet between long-term.

And, the manufacture method of laminate type piezoelectric element of the present invention to after burning till in the described living laminated body that has formed metal level on the described piezoelectric material layer, is removed described metal level, therefore, can produce the laminate type piezoelectric element that easily metal is dispersed in the described inert layer.

Description of drawings

Figure 1A is the stereogram of formation of the laminate type piezoelectric element of expression embodiments of the present invention 1.

Figure 1B is the three-dimensional expanded view of the layer-by-layer state of the piezoelectric body layer of laminate type piezoelectric element of expression execution mode 1 and interior electrode layer.

Fig. 2 is the amplification view of laminated construction that is formed on the outer electrode of piezoelectrics side in the laminate type piezoelectric element of expression execution mode 1.

Fig. 3 A is the stereogram of formation of the laminate type piezoelectric element of expression embodiments of the present invention 2.

Fig. 3 B is the cutaway view of the laminate type piezoelectric element of execution mode 2.

Fig. 4 A is the stereogram when further having formed the conductivity accessory in the laminate type piezoelectric element of execution mode 2.

Fig. 4 B is the cutaway view of Fig. 4 A.

Fig. 5 is the cutaway view of the laminated body before burning till in the manufacture process of the laminate type piezoelectric element of execution mode 2.

Fig. 6 is the cutaway view of injection apparatus of the present invention.

Fig. 7 represents the stereogram of the formation of the laminate type piezoelectric element of example in the past.

Fig. 8 is the expression in the past cutaway view of the formation of the laminate type piezoelectric element of example different with Fig. 7.

Among the figure: 1-piezoelectrics, 2-internal electrode, 3-groove, 4, the 15-outer electrode, the 6-lead, 7-conductivity accessory, 8-electrode layer, 10-lamination-type piezoelectric element, 10a-gives birth to laminated body, 11-active portion, the 12-inert layer, 14-metal, the 1st layer of 15a-outer electrode, the 15b-intermediate layer, 15c-outer electrode outermost layer, 31-accepting container, the 33-spray-hole, 35-valve, 43-piezo actuator.

Embodiment

Below, the laminate type piezoelectric element of embodiments of the present invention is at length described.

Execution mode 1.

Figure 1A, B are the figure of formation of the laminate type piezoelectric element of expression embodiments of the present invention 1, and wherein, Figure 1A is that stereogram, Figure 1B are the three-dimensional expanded views of the layer-by-layer state of expression piezoelectric body layer and interior electrode layer.In addition, Fig. 2 is the amplification view of laminated construction of the outer electrode that is formed on the piezoelectrics side of expression laminate type piezoelectric element of the present invention.

The laminate type piezoelectric element of present embodiment 1, shown in Figure 1A, Figure 1B, a pair of opposed side in the laminated body 13 that is formed by alternative stacked piezoelectrics 1 and internal electrode 2 forms outer electrode 15 respectively, expose internal electrode 2 ends in laminated body 13 sides that form outer electrode 15 every one deck, and the internal electrode 2 that outer electrode 15 and this are exposed is connected.

In addition, be provided with the inert layer 12a that forms by piezoelectrics 1 at the stack direction two ends of laminated body 13.Here, under the situation that the laminate type piezoelectric element with present embodiment 1 uses as the lamination-type piezo actuator, lead can be fastened on the outer electrode 15 with soft solder, and described lead is connected the external voltage supply unit.

Configuration internal electrode 2 between piezoelectric body layer 1, this internal electrode 2 is for example formed by metal materials such as silver-palladiums.In laminate type piezoelectric element, add the voltage of regulation by internal electrode 2 to each piezoelectrics 1, thereby, make piezoelectrics 1 produce the displacement that causes by reciprocal piezoelectric effect.

Otherwise, since inert layer 12a be by a plurality of piezoelectrics 1 that are not equipped with internal electrode 12 the layer constitute, so even applied voltage can not produce displacement yet.

Here, especially in the laminate type piezoelectric element of present embodiment 1, as shown in Figure 2, it is characterized by: lamination more than 3 layers outer electrode 15 and constitute.Like this, constituting outer electrode 15 by the layer more than 3 layers is in order to improve the durability of laminate type piezoelectric element.

Promptly, driving under the situation of outer electrode 15 by individual layer or 2 layers of laminate type piezoelectric element that constitutes, sometimes be the be full of cracks that produces of starting point with the surface of outer electrode 15 and be that the be full of cracks that starting point produces engages that outer electrode 15 produces and breaks with outer electrode 15 and the interface of piezoelectrics 1.And externally electrode 15 is under 2 layers the situation, makes piezoelectrics produce change in size continuously repeatedly if drive laminate type piezoelectric element, then exists in the problem that generation is peeled off between above-mentioned 2 layers.Especially, being made as the external electrode layer and the external electrode layer that glass is less that join with piezoelectrics 1 at the external electrode layer that will add glass in order to improve outer electrode 15 and the connecting airtight intensity of piezoelectrics 1 is located at its outside and constitutes under the situation of 2 layers of structure the above-mentioned problem of peeling off of easier generation.

Therefore, produce the outer electrode 15 of the laminate type piezoelectric element of change in size during driving continuously repeatedly, require to guarantee and the connecting airtight and in lamination-type piezoelectric element change in size, can stretch of piezoelectrics 1.In order to satisfy this requirement, in present embodiment 1, outer electrode 15 is set as following such sandwich construction.That is, outer electrode 15 is by comprising constituting more than 3 layers of the 1st layer of 15a, external electrode layer outermost layer 15c of external electrode layer and its intermediate layer.

In this outer electrode 15, the layer that joins with piezoelectrics 1 is that the 1st layer of 15a of external electrode layer is the layer big with the bond strength of piezoelectrics, is the electrode layer that Young's modulus is little and resistivity is little from the outermost layer 15c of piezoelectrics 1 lamination farthest.And, being positioned at its middle intermediate layer is the layer of the stress of the change in size generation when relaxing because of the driving laminate type piezoelectric element, simultaneously, also be with respect to the 1st layer of 15a of external electrode layer that joins with piezoelectrics and be positioned at outermost external electrode layer outermost layer 15c and all have the layer that connects airtight power.

In addition, change in size in order to prevent because of the laminate type piezoelectric element Continuous Drive make produce between piezoelectrics 1 and the outer electrode 15 peel off or externally produce in the electrode layer peel off or when driving externally the be full of cracks that produces of electrode 15 cause broken string, each layer is continuous continuously in the preferred outer electrode 15 of lamination more than 3 layers.And, if consider the flatness and the production of outer electrode 15, more preferably below 5 layers.

In addition, the electric conducting material that constitutes outer electrode 15 is wished the metal that resistivity is low and hardness is low (for the stress aspect consideration that fully absorbs because of the flexible generation of actuator).Preferred gold, silver or copper.More preferably copper or silver, thus make laminate type piezoelectric element with durability.Most preferably silver-colored, thus make the laminate type piezoelectric element that has more durability.

And in the present invention, the thickness of the 1st layer of 15a of outer electrode that joins with piezoelectrics 1 in the preferred outer electrode 15 is below the 10 μ m.Here, the thickness of the 1st layer of 15a of so-called outer electrode is the mean value of outer electrode the 1st layer thickness that can confirm behind the section with microscopic examination laminate type piezoelectric elements such as SEM.Surpass under the situation that 10 μ m drive laminate type piezoelectric element at thickness, the 1st layer of the outer electrode that joins with piezoelectrics is easy to generate be full of cracks along with size of component changes, under the situation of especially element elongation, be applied in tensile stress.Therefore, be below the 10 μ m by making thickness, do not produce the outer electrode that chaps and have durability even then can make the producing component change in size yet.Below the preferred 5 μ m, more preferably below the 3 μ m, thereby can further improve durability.In addition, most preferably make the thickness of the 1st layer of 15a of outer electrode be that 0.5 μ m is above and 2 μ m are following and greatly improve durability.

And the thickness of each external electrode layer beyond preferred the 1st layer of 15a is thicker than the 1st layer of 15a, and so, the be full of cracks that can effectively be suppressed at the generation of outer electrode 15 outermost layers is propagated.In order to suppress above-mentioned crevasse crack propagation, the 1st layer of 15a each layer thickness in addition is preferably more than the 5 μ m, more preferably more than the 10 μ m, most preferably is made as more than the 15 μ m.In view of the above, the durability of outer electrode 15 integral body increases.In addition, if the whole thickness of the stack direction of outer electrode 15 is more than the 15 μ m, then can bear the laminate type piezoelectric element Continuous Drive.And, if be 20 μ m above, be preferably more than the 30 μ m, then can prevent because of crevasse crack propagation produces broken string, simultaneously owing to can reduce the resistance value of outer electrode 15, so can suppress the heating of outer electrode 15.

On the other hand, when whole thickness surpassed 100 μ m, because outer electrode 15 can not be followed piezoelectrics 1, so displacement obviously descends, therefore, whole thickness is 30～100 μ m more preferably.

And in the present invention, preferred the 1st layer of 15a of outer electrode contains more metal oxide than the 2nd layer of 15b of outer electrode that covers on the 1st layer of 15a of this outer electrode.This be because: at the metal oxide of the 1st layer of 15a that joins with piezoelectrics 1 after a little while than the 2nd layer of 15b, the resistivity of the 1st layer of 15a is littler than the 2nd layer of 15b, therefore, when driving laminate type piezoelectric element, the 1st layer of 15a that current direction resistivity is little, thereby the 1st layer of 15a is overheated, makes between piezoelectrics 1 and the 1st layer of 15a and produces the temperature rising generation thermal runaway of peeling off or making laminate type piezoelectric element.

Here, can select in 1～15 family in the periodic table of elements oxide arbitrarily for use, especially, be preferably and to form Si, B, Bi, Pb, Zn, Al, Ca, Ba, Ti, the Zr of glass, the oxide of terres rares in the temperature below 1000 ℃ as metal oxide.And,, then can further form noncrystalline, so more preferably with low temperature if be the oxide of Si, B, Bi, Pb, Zn.In view of the above, laminate type piezoelectric element is constituting under the heat-treat condition of outer electrode, and the 1st layer of 15a and piezoelectrics 1 firmly connect airtight.Especially, in order to make the high laminate type piezoelectric element of durability, the metal oxide amount that preferred outer electrode is the 1st layer is more than the 30 volume %, more preferably more than the 50 volume %, most preferably is more than the 70 volume %.

And in the present invention, the metal oxide that is contained among the outermost layer 15c of preferred outer electrode 15 lacks than other any external electrode layers.In view of the above, can reduce the Young's modulus of outermost layer 15c, therefore, even the Continuous Drive laminate type piezoelectric element, outer electrode stretches along with size of component changes, and can suppress the be full of cracks that outer electrode produces easily.And,,, therefore do not have thermal runaway even the Continuous Drive element can be not overheated yet owing to can make the low electrode of resistivity.In addition, by increasing metal ingredient, even and solder or welding become easily or situation about engaging by electroconductive resin under also can reduce contact resistance.

Here, if the metal oxide of the 1st layer of 15a external electrode layer in addition all lacks than the electrode layer of the 1st layer of 15a, but though the then heating of suppression element, but in order to improve the power of connecting airtight of external electrode layer, can in layer, not produce and peel off, and more preferably metal oxide reduces successively from the 1st layer of 15a electrode layer laterally.That is to say, with the amount of the metal oxide of outer electrode 15 each layers be the 1st layer＞the 2nd layer＞the 3rd layer＞...＞outermost mode stage ground control amount, can make adjacent external electrode layer hot Peng Zhang Department number to each other approaching, can improve the intensity of connecting airtight of each interlayer.

In addition, the amount of the constituent of outer electrode 15 is come specific by analytical methods such as EPMA (Electron Probe MicroAnalysis) methods.Especially, in order to make the high laminate type piezoelectric element of durability, the metal oxide amount of outermost layer 15c is below the 30 volume % in the preferred outer electrode 15, more preferably below the 10 volume %, is preferably below the 5 volume %.

And the preferable alloy oxide is mainly glass in the present invention.In view of the above, can suppress because of externally forming the problem that intermetallic compound becomes fragile electrode in the electrode 15.And glass ingredient is diffused into the intergranular of the metal ingredient that constitutes outer electrode 15, and outer electrode 15 is connected airtight with piezoelectrics 1 securely.

Then, the method for making to laminate type piezoelectric element of the present invention describes.

In the method, at first, will be by PbZrO ₃-PbTiO ₃Be mixed and made into slurry Deng the preburning powder of the piezoelectric ceramic of perovskite (perovskite) the type oxide that constitutes with by adhesive and DBP (Dibutyl phthalate), DOP plasticizer such as (metatitanic acid dioctyl esters) that organic polymers such as acrylic acid series, butyral system constitute.Then, utilize the known band methods of forming such as the skill in using a kitchen knife in cookery or stack method of scraping this slurry to be made the ceramic green sheet that becomes piezoelectrics 1.

Then, in the metal dust of formation internal electrodes 2 such as silver-palladium, add making conductive pastes such as metal oxide, adhesive and plasticizer such as mixed oxidization silver, by methods such as silk screen printings its thickness with 1～40 μ m is printed on the upper surface of described each raw cook again.

Then, lamination is a plurality of to have printed the raw cook of conductive paste at upper surface, and this laminated body after carrying out the unsticking mixture under the set point of temperature, is burnt till with 900～1200 ℃, and made laminated body 13.

At this moment, as implement to be described in detail in the mode 2, by in the part raw cook of inert layer 12a, adding the metal dust that silver-palladium etc. constitutes internal electrode 2, and can make inert layer 12a and other parts contractive action state and shrinkage when sintering consistent, can form the laminated body of densification.

In addition, laminated body 13 is not limited to make by above-mentioned method for making, so long as can make the laminated body 13 that a plurality of piezoelectrics of alternative stacked 1 and a plurality of internal electrodes 2 form, by which kind of method for making forms and all can.

Then, alternately form the internal electrode 2 that does not expose the internal electrode 2 that exposes the end and end in the laminate type piezoelectric element side.

Then, add adhesive and make silver-colored glass conductive paste in glass powder, it is configured as sheet, the former density of the sheet after the control dry (making solvent evaporates) is 6～9g/cm ³Again with this sheet transfer printing on the outer electrode formation face of column laminated body 13, the firing temperature of the temperature higher and temperature below the silver point (965 ℃) and laminated body 13 than glass softening point (℃) the temperature below 4/5 under carry out roasting, adhesive ingredients in the sheet that utilizes silver-colored glass conductive paste making is scattered and disappeared, can form the outer electrode 15 that constitutes by the porous matter electric conductor that is tridimensional network.

At this moment, though can be to carry out roasting behind the multilayer tablet, also can just carry out roasting for 1 layer by every lamination the cream lamination that constitutes outer electrode,, stacked superior on production for once carrying out roasting behind the sheet of multilayer.And, externally under the situation that every layer of electrode layer all changes glass ingredient, though can every amount that all changes glass ingredient reach, if but think and will constitute as thin as a wafer glass enriched layer near the face of piezoelectrics, then also can utilize methods such as silk screen printing behind printed glass enrichment cream on the laminated body, lamination multilayer tablet again.At this moment, also can not print and adopt sheet below the 5 μ m.

In addition, for forming neck effectively, make silver in the silver-colored glass conductive paste and internal electrode 2 diffusion bond and making space in the outer electrode 15 residual effectively and then make the consideration of outer electrode 15 and column laminated body 13 side local engagement, preferred 500～800 ℃ of the sintering temperature of described silver-colored glass conductive paste.In addition, the softening point of the glass ingredient in the silver-colored glass conductive paste is preferred 500～800 ℃.

When sintering temperature was higher than 800 ℃, the excessive sintering of the silver powder of silver-colored glass conductive paste can not form the porous matter electric conductor that is effective tridimensional network, can make outer electrode 15 too fine and close.Its result, the Young's modulus of outer electrode 15 is too high, can not fully absorb the stress when driving, and outer electrode 15 might produce broken string.Preferably carry out roasting with interior temperature with 1.2 times of glass softening point.

On the other hand, sintering temperature than 500 ℃ of low situations under owing to do not carry out diffusion bond fully between internal electrode 2 ends and the outer electrode 15,, might between internal electrode 2 and outer electrode 15, produce spark during driving so do not form neck.

Then, be immersed in the silicone rubber solution and by the laminated body 13 that will form outer electrode 15 and carry out vacuum degassing silicone rubber solution, and at the inner filled silicon rubber of the groove of laminated body 13, afterwards, mention laminated body 13 from silicone rubber solution, silicon rubber is coated in laminated body 13 sides.Then, harden by making the described silicon rubber that is filled in groove inside and is coated in column laminated body 13 sides, and reach laminate type piezoelectric element of the present invention.

And, externally connect lead on the electrode 15, the direct voltage of adding 0.1～3kV/mm for pair of external electrodes 15 via this lead is to laminated body 13 processing that polarizes, thereby, reach the lamination-type piezo actuator that has utilized laminate type piezoelectric element of the present invention.The voltage supply unit of lead with the outside is connected, and when giving internal electrode 2 applied voltages via lead and outer electrode 15, each piezoelectrics 1 is bigger because of the reciprocal piezoelectric effect displacement.In view of the above, can bring into play as for example to the function of the automobile fuel injection valve of engine spray fueling.

Execution mode 2.

Below, the laminate type piezoelectric element of embodiments of the present invention 2 is described.

The basic comprising of active portion 11 is identical with the laminate type piezoelectric element of execution mode 1 in the laminated body 10 of the laminate type piezoelectric element of present embodiment 2, it is characterized in that the formation of inert layer 12.

Fig. 3 A, B are the figure of formation of the laminate type piezoelectric element of expression embodiments of the present invention 2, and wherein, Fig. 3 A is that stereogram, Fig. 3 B are the cutaway views of the layer-by-layer state of the active portion that forms of expression lamination interior electrode layer and piezoelectrics and protective layer.

In addition, shown in Fig. 3 A, B, in the laminate type piezoelectric element of present embodiment 2, the side of the active portion 11 that forms at alternative stacked piezoelectrics 1 and internal electrode 2, be formed be used for between outer electrode 4 and the internal electrode 2 every the groove of one deck insulation, thereby the mode that conducts every one deck with internal electrode 2 and outer electrode forms outer electrode 4.

Below, be that the center describes with the inert layer 12 of the formation of feature with present embodiment 2.

In the laminate type piezoelectric element of present embodiment 2, inert layer 12 is that matrix constitutes with the piezoelectrics identical with piezoelectrics 1, it is characterized by and also contain dispersed metal 14 in inert layer 12.

Promptly, the invention of the laminate type piezoelectric element of execution mode 2 is because the following uniqueness of the inventor is found and reached based on this opinion, shown in Fig. 3 B, by metal 14 is dispersed in the inert layer 12, thereby, (1) when burning till laminated body 10, relax inert layer 12 and burning till of active portion 11 and shrink poorly, make the few laminate type piezoelectric element of residual stress; (2) in addition, dispersed metal 14 acceleration of sintering when burning till laminated body 10a obtains fine and close laminated body 10, also can bear the stress that the vibration when the laminate type piezoelectric element Continuous Drive produces.

Thereby, having the laminate type piezoelectric element of the execution mode 2 of the inert layer 12 that has disperseed metal 14, superior durability is not even long-time the use can produce deterioration, the reliability height yet.

Here, so-called " having disperseed metal ", the meaning is that to contain the situation of laminated metal like that different with the active layer that for example alternately forms piezoelectrics and internal electrode, typically says, is meant metallic element is diffused in the piezoelectrics of inert layer 12.In addition, also can make metallic element from the surface of inert layer 12 diffusion inside to inert layer 12.The dispersion of this metal 14 can be passed through analytical method such as EPMA (Electron ProbeMicro Analysis) method and come specific.Specifically, as if the arbitrary section of analyzing inert layer with EPMA, then can confirm the distribution of metal.

In addition, the preferred firing temperature of laminate type piezoelectric element relatively of fusing point that is dispersed in the metal 14 in the inert layer 12 is below 1.6 times.This be because: for metal 14 with fusing point higher than above-mentioned fusing point, in inert layer 12, the diffuser efficiency variation of metal.The fusing point of metal 14 be laminate type piezoelectric element firing temperature below 1.6 times the time, can make metallic element easily from inert layer 12 surfaces to inert layer 12 inside.

In addition, under the situation of having added the metal 14 more than 2 kinds or added under the situation of the alloy that is made of metal more than 2 kinds, preferably the fusing point of each metal is below 1.6 times of firing temperature of laminate type piezoelectric element.But, the metal for being unfavorable for disperseing in inert layer 12 need not to this is self-explantory below the above-mentioned fusing point.

And, in the present invention, be dispersed in metal 14 in the inert layer 12 be preferably among Ag, Pd, Cu, Ca, Na, Pb, the Ni more than at least a kind.This be because: the fusing point of these metals is near the firing temperature of laminated body 10a or lower than firing temperature, and therefore, in laminated body 10a sintering process, the diffusion in inert layer 12 comes to life, and promotes metal 14 to disperse equably in inert layer 12.

In addition, make metal 14 the amount in the inert layer 12 of being dispersed in be preferably 0.001～1.0 quality % of inert layer 12.This be because: be 0.001 quality % when following, inert layer 12 is poor with the contraction of active portion 11 when burning till or shrinkage curve is different, produces bigger strain between the two, when the poorest, burn till and is easy to generate delamination after the back produces delamination or long-time use.

In addition, when metal 14 to the 1.0 quality % that disperse were big, the insulating properties deterioration of inert layer 12 diminished the function of inert layer.In addition, in order further to reduce the residual stress after inert layer 12 burns till, bad after not producing laminate type piezoelectric element and burning till, more excellent metal 14 is 0.05 quality %～1.0 quality % with respect to the amount that selects inert layer 12.In addition, even the stress that produces for the vibration for because of the laminate type piezoelectric element Continuous Drive time also has high reliability, the amount of most preferred metal 12 is 0.1 quality %～1.0 quality %.In addition, the amount of metal 14 relative inertness layers 12 can carry out quantitative assay by ICP (Inductively Coupled Plasma Atomic) luminesceence analysis.

And, the preferred 0.1mm～2.0mm of the thickness of inert layer 12.Be 0.1mm when following inert layer 12 thin, therefore, sometimes because the stress that the vibration during the laminate type piezoelectric element Continuous Drive produces destroys inert layer 12.In addition, when thicker than 2.0mm, metal 14 difficulties are distributed in the inert layer 12.Here, if the degree of scatter of metal 14 in inert layer 12 is poor, then metal disperse many parts and metal disperse few part when burning till amount of contraction or shrinkage curve can produce poor, therefore, when burning till contraction, produce bigger strain, burning till back generation delamination or after long-time use, be easy to generate delamination.In addition, inert layer 12 is configured on the both ends of the surface of laminated body 10 stack directions, and so-called inert layer 12 thickness represent to be configured in the thickness of the inert layer on some end faces 12 in the described both ends of the surface.

In addition, the metal 14 that is dispersed in the inert layer 12 is preferably the metal composition that constitutes internal electrode 2.This be because: during metal beyond use constituting the metal of internal electrode 2, when burning till laminated body 10a inert layer 12 and the active portion 11 that comprises internal electrode 2 to burn till shrinkage curve different, sometimes because of burning till contraction generation stress.

Below, the important document beyond the inert layer of execution mode 2 is described.

In the laminate type piezoelectric element of present embodiment 2, the internal electrode 2 that or not internal electrode 2 and the end of exposing in the laminated body side end alternately constitutes, and piezoelectrics 1 part that internal electrode 2 that does not expose in described end and outer electrode are 4 is formed with groove 3.In the present invention, preferably in this groove, form the Young's modulus insulator lower than piezoelectrics 1.Like this, in such laminate type piezoelectric element, owing to can relax the stress that produces because of the displacement in driving, so even Continuous Drive also can suppress the heating of internal electrode 2.

In addition, the firing temperature of laminated body is preferably more than 900 ℃ and below 1200 ℃ in the present invention.This be because: at firing temperature is below 900 ℃ the time, makes owing to firing temperature is low to burn till insufficiently, is difficult to make the piezoelectrics 1 of densification.In addition, this be because: when firing temperature surpassed 1200 ℃, the stress that the deviation of the contraction of the contraction of internal electrode 2 and piezoelectrics 1 produces when burning till became greatly, might produce the crack when the laminate type piezoelectric element Continuous Drive.

In addition, in the laminate type piezoelectric element of present embodiment 2, when adopting lonely outer electrode more than 3 layers described in the execution mode 1, also can obtain the effect identical with execution mode 1.

And outer electrode 4 preferably is made of the porous matter electric conductor that is tridimensional network.If outer electrode 4 can't help to be the porous matter electric conductor formation of tridimensional network, then outer electrode 4 does not have flexible, can not follow the flexible of lamination-type piezo actuator, therefore, the broken string or the outer electrode 4 that produce outer electrode 4 sometimes are bad with the contact of internal electrode 2.

Here, described tridimensional network, be not meant the state that has so-called spherical hole in the electrode 4 externally, and hint is the conducting material powder and the three-dimensional engagement state that links of glass powder of the formation outer electrode 4 as following, promptly, for roasting under than the condition of lower temperature constitutes the conducting material powder and the glass powder of outer electrode 4, the hole does not stop sintering to carry out and exists with the state that links to a certain degree.

The preferred such hole externally voidage in the electrode 4 is 30～70 volume %.Here, so-called voidage is an externally shared ratio in the electrode 4 of space.This be because: if the voidage in the outer electrode 4 is little than 30 volume %, then outer electrode 4 can not bear the stress because of the flexible generation of lamination-type piezo actuator, and outer electrode 4 might break; When externally the voidage in the electrode 4 surpasses 70 volume %, because the resistance value of outer electrode 4 becomes big, so outer electrode 4 generation local pyrexias might cause broken string when flowing through big electric current.

And the piezoelectrics 1 side skin section of preferred outer electrode 4 is formed with the glass enriched layer.This be because: when not having the glass enriched layer, therefore the difficulty that engages with glass ingredient in the outer electrode 4, might cause outer electrode 4 to be not easy and piezoelectrics 1 firm engagement.

In addition, preferably constitute the glass of outer electrode 4 softening point (℃) be the electric conducting material fusing point that constitutes internal electrode 2 (℃) below 4/5.This be because: the softening point that constitutes the glass of outer electrode 4 surpasses 4/5 o'clock of fusing point of the electric conducting material that constitutes internal electrode 2, because the fusing point of the electric conducting material of the softening point of the glass of formation outer electrode 4 and formation internal electrode 2 becomes the temperature of same degree, so the temperature of roasting outer electrode 4 is inevitable near the fusing point that constitutes internal electrode 2, therefore, when roasting outer electrode 4, the electric conducting material of internal electrode 2 and outer electrode 4 condenses and the obstruction diffusion bond, or, sintering temperature can not be set in the fully softening temperature of glass ingredient that makes outer electrode 4, so can not obtain the sufficient joint strength that forms by softening glass sometimes.

And the glass that preferably constitutes outer electrode 4 is noncrystalline.This is that outer electrode 4 can not absorb the flexible stress that causes by the lamination-type piezo actuator, therefore, produces the crack sometimes because in the glass of crystalline.

In addition, the thickness of preferred outer electrode 4 is than the thin thickness of piezoelectric body layer 1.This is because if the thickness of outer electrode 4 is thicker than the thickness of piezoelectric body layer 1, and then because the intensity of outer electrode 4 increases, therefore, when laminated body 10 was stretched, the load at the junction surface of outer electrode 4 and internal electrode 2 increased, and the contact condition of poor takes place sometimes.

Then, the method for making to laminate type piezoelectric element of the present invention describes.

In the method, at first identical with execution mode 1, make the ceramic green sheet that becomes piezoelectrics 1.

Then, this raw cook is cut into any size, be fixed on the framework.

Then, in the metal dust of silver-palladium formation internal electrode 2, add mixed adhesive, plasticizer etc. and make conductive pastes, by methods such as silk screen printings its thickness with 1～40 μ m is printed on described each raw cook upper surface again, prepare the raw cook of active portion 11 usefulness.

Then, prepare on inert layer 12, not have the raw cook of printing conductive cream.

Then, a plurality of active portion 11 usefulness raw cooks of lamination and inert layer 12 are used raw cook, and the laminate portion of overlapping inert layer 12 usefulness raw cooks is positioned at about the laminate portion of active portion 11 usefulness raw cooks that overlapping upper surface printed conductive paste, and simultaneously, exerting pressure makes it to connect airtight.Here, the part that becomes inert layer 12 active portion about in the of 11 the thickness lamination with 0.1～2.0mm a plurality of.

Then, to be cut into suitable size by the raw cook of lamination, as shown in Figure 5, be dispersed in the conductive paste that comprises metal ingredient (for example, Ag, Pd, Cu, Ca, Na, Ni, Pb etc.) in the inert layer and form metal level 8 by printing in the living laminated body 10a both ends of the surface that disposed inert layer 12.Afterwards, after carrying out the unsticking mixture under the temperature of regulation, under 900～1200 ℃ of temperature, burn till, thereby remove metal level 8 by surface grinding machine etc. and make laminated body 10 after burning till burning till the back.

Here, the thickness of the metal level 8 of formation is preferably below the 5mm.This be because: if the thickness of metal level 8 surpasses 5mm, then might be when laminated body 10a burns till because the contraction difference that metal level 8 and inert layer 12 burn till and in metal level 8 generation cracks.

Then, alternately form the internal electrode 2 that does not expose the internal electrode 2 that exposes the end and end in laminated body 10a side, piezoelectrics 1 part that internal electrode 2 that does not expose in the end and outer electrode are 4 forms groove 3, and the formation Young's modulus is than insulators such as low resin of piezoelectrics 1 or rubber this groove 3 in.Here, described groove 3 is formed on active portion 11 sides by intra slice device etc., for the consideration that fully absorbs because of the stress of the flexible generation of laminate type piezoelectric element, constitute the low silver of the preferred Young's modulus of electric conducting material of outer electrode 4 or be the alloy of principal component with silver.

Then, add adhesive and make silver-colored glass conductive paste in glass powder, it is configured as sheet, the former density of the sheet after the control dry (making solvent evaporates) is 6～9g/cm ³Again with this sheet transfer printing on the outer electrode formation face of active portion 11, the temperature higher and the temperature below the silver point (965 ℃) and firing temperature than glass softening point (℃) the temperature below 4/5 under carry out roasting, adhesive ingredients in the sheet that utilizes silver-colored glass conductive paste making is scattered and disappeared, can form the outer electrode 4 that constitutes by the porous matter electric conductor that is tridimensional network.

In addition, for forming interparticle neck effectively, make silver in the silver-colored glass conductive paste and internal electrode 2 diffusion bond and making space in the outer electrode 4 residual effectively and then make the consideration of outer electrode 4 and laminated body side local engagement, preferred 500～700 ℃ of the sintering temperature of described silver-colored glass conductive paste.In addition, the softening point of the glass ingredient in the silver-colored glass conductive paste is preferred 500～700 ℃.

When sintering temperature was higher than 700 ℃, the excessive sintering of the silver powder of silver-colored glass conductive paste can not form the porous matter electric conductor that is effective tridimensional network, can make outer electrode 4 too fine and close.Its result, the Young's modulus of outer electrode 4 is too high, can not fully absorb the stress when driving, and outer electrode 4 might produce broken string.Preferably carry out roasting with interior temperature with 1.2 times of glass softening point.

On the other hand, sintering temperature than 500 ℃ of low situations under, owing to do not carry out diffusion bond fully between internal electrode 2 ends and the outer electrode 4,, might between internal electrode 2 and outer electrode 4, produce spark during driving so do not form interparticle neck.

In addition, the thickness of preferred silver-colored glass conductive paste sheet is than the thin thickness of piezoelectrics 1.For the flexible consideration of following actuator, more preferably below the 50 μ m.

Then, be immersed in the silicone rubber solution and by the active portion 11 that will form outer electrode 4 and carry out vacuum degassing silicone rubber solution, and at the groove 3 inner filled silicon rubbers of active portion 11, afterwards, mention active portion 11 from silicone rubber solution, silicon rubber is coated in active portion 11 sides.Then, harden by making the described silicon rubber that is filled in groove 3 inside and is coated in active portion 11 sides, and reach laminate type piezoelectric element of the present invention.

And, externally connect lead 6 on the electrode 4, the direct voltage of adding 0.1～3kV/mm for pair of external electrodes 4 via this lead 6 is to active portion 11 processing that polarizes, thereby, reach the lamination-type piezo actuator that has utilized laminate type piezoelectric element of the present invention.The voltage supply unit of lead 6 with the outside is connected, and when giving internal electrode 2 applied voltages via lead and outer electrode 4, each piezoelectrics 1 is bigger because of the reciprocal piezoelectric effect displacement.In view of the above, can bring into play as for example to the function of the automobile fuel injection valve of engine spray fueling.

Below, the preferred mode of internal electrode in execution mode 1 and 2 etc. is described.

(internal electrode)

In the present invention, the metal constituent in the internal electrode 2 is a principal component with 8～10 family's metals and/or 11 family's metals preferably.This be because: because above-mentioned metal constituent has high-fire resistance, so can the high-tension electricity body 1 and the internal electrode 2 of firing temperature be burnt till simultaneously.Therefore, because the sintering temperature that can make outer electrode makes than the sintering temperature lowland of piezoelectrics, so can suppress violent counterdiffusion mutually between piezoelectrics and outer electrode.

And, when the amount that is made as M1 (quality %), 11 family's metals at the amount of 8～10 family's metals was made as M2 (quality %), the metal constituent in the preferred internal electrode 2 was a principal component with the metal constituent that satisfies 0＜M1≤15,85≤M2＜100, M1+M2=100.This be because: when 8～10 family's metals surpass 15 quality %, it is big that resistivity becomes, under the situation of Continuous Drive laminate type piezoelectric element, sometimes internal electrode 2 heatings, to make Wei move Te Minus little in having temperature dependent piezoelectrics 1 for this heating functioin, so the displacement of laminate type piezoelectric element diminishes; And, when forming outer electrode 15, though outer electrode 15 and internal electrode 2 mutual diffusion bond, but when 8～10 family's metals surpass 15 quality %, the hardness that has spread the position of internal electrode composition in the outer electrode 15 uprises, produce during driving in the laminate type piezoelectric element of change in size, durability reduces.In addition, for the 11 family's metals that suppress in the internal electrode 2 move to piezoelectrics 1, preferred 8～10 family's metals are more than the 0.001 quality % and below the 15 quality %.In addition, consider, more than the preferred 0.1 quality % and below the 10 quality % for the durability this point that improves laminate type piezoelectric element.In addition, under the situation superior in heat conduction, more high-durability, more preferably more than the 0.5 quality % and below the 9.5 quality %.In addition, under the situation of pursuing further high durability, further more than the preferred 2 quality % and below the 8 quality %.

Here also because: during less than 85 quality %, it is big that the resistivity of internal electrode 2 becomes at 11 family's metals, under the situation of Continuous Drive laminate type piezoelectric element, internal electrode 2 heatings sometimes.In addition, in order to suppress 11 family's metals in the interior metal 2 to the migration of piezoelectrics 1, preferred 11 family's metals are that 85 quality % are above and below the 99.999 quality %.In addition, consider, more than the preferred 90 quality % and below the 99.9 quality % for the durability this point that improves laminate type piezoelectric element.In addition, under the situation of the higher durability of needs, more preferably more than the 90.5 quality % and below the 99.5 quality %.In addition, more than further preferred 92 quality % under the situation of seeking further high durability and below the 98 quality %.

8～10 family's metals that quality % is shown of metal ingredient, 11 family's metals can pass through analytical method such as EPMA (Electron Probe Micro Analysis) method and come specific in the above-mentioned internal electrode 2.

And the metal ingredient in the internal electrode 2 of the present invention is preferred: 8～10 family's metals are among Ni, Pt, Pd, Rh, Ir, Ru, the Os more than at least a kind, 11 family's metals are among Cu, Ag, the Au more than at least a kind.This be because: they be in recent years on the alloy powder synthetic technology the superior metal of production form.

And the metal ingredient in the internal electrode 2 is preferred: 8～10 family's metals are among Pt, the Pd more than at least a kind, 11 family's metals are among Ag, the Au more than at least a kind.In view of the above, can form superior for heat resistance, internal electrode 2 that resistivity is little.

And 8～10 family's metals of the metal ingredient in the internal electrode 2 are preferably Ni.In view of the above, can form the internal electrode 2 of superior for heat resistance.

In addition, the metal ingredient in the internal electrode 2 more preferably: 11 family's metals are Cu.In view of the above, can form the superior internal electrode 2 of the low heat conductivity of hardness.

And, preferably in internal electrode 2, add oxide, nitride or carbide with above-mentioned metal constituent.In view of the above, the intensity of internal electrode increases, and the durability of laminate type piezoelectric element improves.Especially, the counterdiffusion and improve the intensity of connecting airtight of internal electrode and piezoelectrics mutually of oxide and piezoelectrics is so be more preferably.And preferred described inorganic composition is below the 50 volume %.In view of the above, can make the bond strength between internal electrode 2 and the piezoelectrics 1 littler than the intensity of piezoelectrics 1.More preferably below the 30 volume %, thereby can improve the durability of laminate type piezoelectric element.

Preferred described oxide is with by PbZrO ₃-PbTiO ₃The perofskite type oxide that constitutes is a principal component.In addition, the amount of oxide of interpolation etc. can recently be calculated from the composition area the internal electrode of the section SEM picture of laminate type piezoelectric element.

(piezoelectrics)

In the present invention, piezoelectrics 1 preferably are principal component with the perofskite type oxide.Like this, for example by with barium titanate (BaTiO ₃) when being the formation such as Ca-Ti ore type piezoceramic material of representative, because the piezoelectric strain constant d of its piezoelectric property of performance ₃₃Height, thus displacement can be increased, and, also can burn till piezoelectrics 1 and internal electrode 2 simultaneously.As the above-mentioned piezoelectrics that illustrate 1, preferably with by piezoelectric strain constant d ₃₃Than higher PbZrO ₃-PbTiO ₃The perofskite type oxide that constitutes is a principal component.

And firing temperature is preferred more than 900 ℃ and below 1000 ℃.This be because: at firing temperature is below 900 ℃ the time, and firing temperature is low and burn till insufficiently, is difficult to make fine and close piezoelectrics 1; In addition, if firing temperature surpasses 1000 ℃, then the bond strength of the contraction of internal electrode 2 and piezoelectrics 1 becomes big.

In addition, the internal electrode 2 that or not internal electrode 2 and the end of exposing in the side end of laminate type piezoelectric element of the present invention alternately constitutes, the internal electrode 2 that does not expose described end and the side between the outer electrode 15 form under the situation of groove, preferably form the Young's modulus insulator lower than piezoelectrics 1 in this groove.In view of the above, in such laminate type piezoelectric element, can relax the stress that the displacement in the driving process produces, therefore, even Continuous Drive also can suppress the heating of internal electrode 2.

(the conductivity accessory 7 on the outer electrode 4)

And, in the present invention, the preferred conductivity accessory 7 that constitutes by the conductive adhesive of having buried wire netting or net-shaped metal plate underground of the outer surface setting of electrode 4 like that externally shown in Fig. 4 B.If externally the outer surface of electrode 4 is not provided with conductivity auxiliary part 7, then feeding big electric current to laminate type piezoelectric element when driving, outer electrode 4 can not bear big electric current and produce local pyrexia, might break.In addition, owing in conductive adhesive, be embedded with wire netting or net-shaped metal plate, produce the crack so can prevent to conduct electricity living binding agent.

In addition, wire netting is meant the structure that the braided metal line forms, and net-shaped metal plate is meant formation hole on metallic plate and forms netted structure.

In addition, if externally the outer surface of electrode 4 does not use wire netting or net-shaped metal plate, then the flexible stress that produces of laminate type piezoelectric element directly acts on outer electrode 4, thereby might outer electrode 4 be peeled off easily from the laminate type piezoelectric element side.

In addition, preferred conductive adhesive is made of the polyimide resin that has disperseed electroconductive particle.This be because: by using polyimide resin, even also can have when at high temperature driving laminate type piezoelectric element than higher thermal endurance, and by using the stable on heating polyimide resin that has like this than higher, conductive adhesive is also kept high adhesion strength easily.And electroconductive particle is preferably silver powder.This be because: use the lower silver powder of resistance value by electroconductive particle, be easy to suppress the local pyrexia of conductive adhesive.In addition, be dispersed in the high polyimide resin of thermal endurance by the silver powder that resistance value is low, even at high temperature use, it is low and keep the conductivity auxiliary part 7 of high bond strength also can to form resistance value.

In addition, used here electroconductive particle is preferably aspheric particles such as sheet or needle-like.This is because form nonspherical particles such as sheet or needle-like by the shape with electroconductive particle, can make the polymerization between this electroconductive particle firm, can further improve the shear strength of this conductive adhesive.

More than the laminate type piezoelectric element of execution mode 1 and 2 has been carried out specifically explaining, but, laminate type piezoelectric element of the present invention and manufacture method thereof are not limited thereto, and can carry out numerous variations in the scope that does not break away from main idea of the present invention.For example, when making metal 14 be distributed in the inert layer, as mentioned above in the laminated body 10 both ends of the surface printed metal layer 8 of configuration inert layer 12, burn till metal 14 be dispersed in the inert layer 12, still, also can in the raw cook that forms inert layer 12, add metal 14 in advance.In addition, under the situation of disperseing fusing point lower metal 14, for example than the firing temperature of laminated body 10, also can in crucible, dispose laminated body 10a, metal 14 is set in its vicinity burns till simultaneously, thereby, make from the metal vapors evaporation of metal 14 volatilizations to be distributed to the inert layer 12.

In addition, though the example that the opposed side in active portion 11 is formed outer electrode 4 is illustrated as mentioned above,, the present invention also can for example form pair of external electrodes 4 in adjacent side.

Execution mode 3.

Below, injection apparatus of the present invention is described.This injection apparatus utilizes laminate type piezoelectric element of the present invention to constitute.

Fig. 6 represents injection apparatus of the present invention, is provided with spray-hole 33 at accepting container 31 1 ends, in addition, is accommodating the needle-valve 35 that can open and close spray-hole 33 in accepting container 31.

Can be provided with fuel passage 37 communicatively at spray-hole 33, this fuel passage 37 links with outside fuel supply source, usually with certain high pressure to fuel passage 37 fuelings.Thereby, forming when needle-valve 35 is opened spray-hole 33, the fuel that supplies to fuel passage 37 sprays in the not shown fuel chambers of internal combustion engine with certain high pressure.

In addition, it is big that the diameter of the upper end of needle-valve 35 becomes, and constitutes the piston 41 that can slide mutually with the cylinder body 39 in being formed on accepting container 31.And, in accepting container 31, contain above-mentioned piezo actuator 43.

In such injection apparatus, if piezo actuator 43 is applied in voltage and extends, then piston 41 is urged, and needle-valve 35 stops up spray-hole 33, stops the supply of fuel.In addition, if stop to apply voltage, then piezo actuator 43 shrinks, and disk spring 45 pushes back piston 41, and spray-hole 33 is communicated with fuel passage 37, carries out the injection of fuel.

In addition, injection apparatus of the present invention is not limited in above-mentioned execution mode, for example, except carrying fuel injection device in automobile engine, the liquid injection apparatus of ink-jet etc., driving element in the precision positioning device of Optical devices etc. or the anti-locking apparatus of vibration etc., perhaps carry at combustion pressure sensor, seismological sensor, acceleration transducer, load sensor, ultrasound sensors, voltage sensitive sensor, sensor element in the yaw rate sensor etc., and carry at piezoelectric gyroscope, Piezoelectric switches, piezoelectric transformer, outside the circuit element in the piezoelectricity circuit breaker etc., so long as utilize the element of piezoelectric property, just can be suitable for certainly.

[embodiment]

Below, embodiments of the invention are described.

(embodiment 1)

As embodiment 1, made the lamination-type piezo actuator that the laminate type piezoelectric element by embodiment of the present invention 1 constitutes by the mode of the following stated.

At first, make that to have mixed with average grain diameter be the lead zirconate titanate (PbZrO of 0.4 μ m ₃-PbTiO ₃) be preburning powder, adhesive, and the slurry of plasticizer of the piezoelectric ceramic of principal component, make the ceramic green sheet that thickness is the piezoelectrics 1 of 150 μ m with the scraper method.

Form the conductive paste of 3 μ m thickness by silk screen print method on the one side of ceramic green sheet, and this conductive paste added adhesive and form in silver-palladium alloy (silver-colored 95 quality %-palladiums, 5 weight %), 300 sheets that are formed with this conductive paste of lamination burn till.Burn till is to keep afterwards, burn till at 1000 ℃ at 800 ℃.

Then, forming the degree of depth in the internal electrode end of laminated body side every one deck by slicing device is that 50 μ m, width are the groove of 50 μ m.

Then, composition as shown in table 1 is such, to average grain diameter is that silver powder and the remainder of the sheet of 2 μ m is that the silicon of 2 μ m is that total weight 100 mass parts of adding relative silver powder and glass powder in 640 ℃ the mixture of amorphous glass powder are the adhesive of 8 mass parts as the softening point of principal component with average grain diameter, fully mixes and makes silver-colored glass conductive paste.On mould release film, form the silver-colored glass conductive paste of making like this by silk screen printing, after the drying, peel off, obtain the sheet of silver-colored glass conductive paste from mould release film.

Then, as the lamination condition of table 1, the sheet transfer printing of described silver-colored glass cream is carried out lamination on 15 of the outer electrodes of laminated body 13, formed outer electrode 15 in 30 minutes 700 ℃ of following roastings.

Afterwards, lead is connected on the outer electrode 15, the lamination-type piezo actuator that has utilized laminate type piezoelectric element such shown in Figure 1A, the B is made in the DC electric field that adds 15 minutes 3kV/mm to the outer electrode 15 of positive pole and negative pole via the lead processing that polarizes.

The laminate type piezoelectric element that obtains is added the direct voltage of 170V, and all as a result lamination-type piezo actuators obtain along the displacement of stack direction 45 μ m.And, under the room temperature to this laminate type piezoelectric element with the frequency of 150Hz add 0～+ alternating voltage of 170V drives test, being tested to Continuous Drive is 1 * 10 ⁹It is inferior,

In addition, the layer thickness of outer electrode 15 and amount of glass are measured by SEM measurement section.Thickness is that 5 mean value is calculated from the SEM picture, and amount of glass is the area of calculating electrode layer from SEM and EPMA, calculates the area of glass part wherein again, and the area of calculating the area that obtains likens to and is volume %.The result is as shown in table 1.

Table 1-1

In table 1-1, amount of glass by volume % is represented.

Table 1-2

In table 1-2, initial stage displacement A represents the displacement (μ m) of A-stage, and the maximum displacement B after the Continuous Drive is illustrated in after the Continuous Drive (1 * 10 ⁹Inferior) maximum displacement (μ m).

In addition, in table 1-2, move the quantitative change rate and represent that displacement after the Continuous Drive with respect to the rate of change (%) of the displacement of A-stage, gets and make A, B, with | (A-B)/A * 100| represents.

As known from Table 1, the specimen coding 1,2,13 of comparative example, because constituting the number of plies of outer electrode 15 is below 2 layers, so when Continuous Drive lamination-type piezo actuator, because of the change in size of piezoelectrics 12, the load that is added on the interface of piezoelectrics 12 and outer electrode 15 becomes big, produces be full of cracks from described interface to outer electrode 15, and, peel off in the generation of described interface.

Relative therewith, in the specimen coding 3～12 of the embodiment of the invention, owing to be the lamination-type piezo actuator of outer electrode to constitute more than 3 layers, so Continuous Drive 1 * 10 ⁹After inferior, the element displacement can obviously not reduce yet, and has as the required effective displacement of lamination-type piezo actuator, in addition, can make not producing the lamination-type piezo actuator that thermal runaway and misoperation have superior durability.

(embodiment 2)

The material of the internal electrode 2 of the lamination-type piezo actuator of the sample No.7 of change embodiment 1 is formed, and measures the rate of change of the displacement of each sample.Here, the rate of change of so-called displacement is that laminate type piezoelectric element to each sample reaches and drives number of times 1 * 10 ⁹The displacement (μ m) of displacement when inferior (μ m) and the laminate type piezoelectric element A-stage of beginning before the Continuous Drive compares and obtains.Its result is illustrated in the table 2.

Table 2

In table 2, the metal in the internal electrode represents that with quality % each metal in the internal electrode is with respect to the ratio of the metal lump scale of construction.In addition, the displacement rate of change represents that displacement after the Continuous Drive with respect to the rate of change (%) of the displacement of A-stage, destroys expression and damages because of migration.

Find from table 2: internal electrode 2 is made as under the situation of 100% silver medal at sample No.1, laminate type piezoelectric element owing to silver migration damages can not Continuous Drive; In addition, sample No.18, because in the metal constituent in the internal electrode 2, the amount of 8～10 family's metals surpasses 15 quality %, in addition, the amount of 11 family's metals is less than 85 quality %, so the resistivity of internal electrode 2 is big, and when the Continuous Drive laminate type piezoelectric element, generate heat, the displacement of lamination-type piezo actuator reduces.

Relative therewith, also find: sample No.2～14, because the metal constituent in the internal electrode 2 is M1 quality % at the amount with 8～10 family's metals, be principal component with the metal constituent that satisfies 0＜M1≤15,85≤M2＜100, M1+M2=100 quality % when the amount of 11 family's metals is M2 quality %, so can reduce the resistivity of internal electrode 2, even Continuous Drive also can be suppressed at internal electrode 2 and produce heating, therefore, can make the stable lamination-type actuator of element displacement.

And find: sample No.15～17 also can reduce the resistivity of internal electrode 2, produce heating even Continuous Drive also can be suppressed at internal electrode 2, therefore, can make the stable lamination-type actuator of element displacement.

In addition, the present invention and in being confined to the foregoing description is the numerous variations that can carry out to a certain degree in not breaking away from the Fan Wall of main idea of the present invention.

(embodiment 3)

In embodiment 3, as following, make the lamination-type piezo actuator that constitutes by laminate type piezoelectric element of the present invention.

At first, making has mixed with lead zirconate titanate (PbZrO ₃-PbTiO ₃) for the preburning powder of the piezoelectric ceramic of principal component, adhesive, and the slurry that obtains of plasticizer, utilize the scraper legal system to make the ceramic green sheet that becomes piezoelectrics 11 of thickness 150 μ m.

Form the sheet of 3 μ m thickness on the one side of this ceramic green sheet by silk screen print method printing conductive cream, 300 such sheets of lamination prepare to be used for active layer.In addition make in addition the raw cook (not forming conductive paste) of the thickness 100 μ m that are used to constitute inert layer 12, and the lamination inert layer is suppressed with 5～20 with 300 of raw cooks, inert layer with 5～20 of raw cooks, active layer successively.Wherein this conductive paste is to have added adhesive to form in the silver-palladium alloy that ratio of components forms arbitrarily.

Then, have the laminated body 10a both ends of the surface of inert layer 12, promptly forming metal level 8 by silk screen print method with the thickness printing conductive cream of 5 μ m at the end face of inert layer 12.Afterwards, remove metal level 8 by surface grinding machine etc. after burning till certain hour under 1000 ℃, wherein this conductive paste is to have added the conductive paste that adhesive obtains or added the conductive paste that adhesive obtains in Pd, Ni, Cu, Ag, Na, Pb, W or Mo in silver-palladium alloy.

Then, form the groove 3 of the degree of depth 50 μ m, width 50 μ m every one deck in the internal electrode end of laminated body side by slicing device, filled silicon rubber makes it sclerosis in this groove 3.

Then, to average grain diameter is that silver powder 90 volume % and the remainder of the sheet of 2 μ m is that the silicon of 2 μ m is that the total weight 100 of adding relative silver powder and glass powder in 640 ℃ the mixture of amorphous glass powder 10 volume % is that mass parts is the adhesive of 8 mass parts as the softening point of principal component with average grain diameter, fully mixes and makes silver-colored glass conductive paste.On mould release film, form the silver-colored glass conductive paste of making like this by silk screen printing, after the drying, peel off, obtain the sheet of silver-colored glass conductive paste from mould release film.The former density of measuring this sheet through Archimedes's method is 6.5g/cm ³

Secondly, the sheet transfer printing of silver-colored glass cream on the external electric pole-face of laminated body, 650 ℃ of following roastings 30 minutes, is formed the outer electrode that is made of the porous matter electric conductor that is tridimensional network.Also have, the result that the voidage of the outer electrode of this moment is measured through the cross sectional photograph of image analysis apparatus parsing outer electrode is 40%.In addition, added K in the raw material of piezoelectrics 1, internal electrode 2 and outer electrode 4 ₂CO ₃Or Na ₂CO ₃Powder.Contained alkali metal is to utilize the icp analysis method and detected in the piezoelectrics of the sintered body that obtains, internal electrode and the outer electrode.

In addition, made the laminate type piezoelectric element of the electrode of not switching on mutually with outer electrode in the inert layer setting as shown in Figure 8 as a comparative example.Here, the piezoelectrics of described laminate type piezoelectric element are identical with above-mentioned composition of the present invention, and in addition, the silver in the internal electrode of comparative example and the ratio of palladium constituted with 95: 5.In addition, in table 3-1, in the specimen coding 1 of comparative example, because dispersed metal not in the inert layer is expressed as sky hurdle (-) so the fusing point ratio of dispersed metal and dispersed metal are formed the hurdle.And, successively the lamination inert layer with 10, active layer with 300, inert layer with after 10, by the method identical with above-mentioned the present invention outer electrode is set, lead waits and makes laminate type piezoelectric element (specimen coding 1 of table 3).

Afterwards, lead 6 is connected on the outer electrode 4, the lamination-type piezo actuator that has utilized laminate type piezoelectric element such shown in Fig. 3 A, the B is made in the DC electric field that adds 15 minutes 3kV/mm to the outer electrode 4 of positive pole and negative pole via lead 6 processing that polarizes.

The laminate type piezoelectric element that obtains is added the direct voltage of 170V, and the result obtains the displacement of 45 μ m along stack direction.And, under the room temperature to this laminate type piezoelectric element with the frequency of 150Hz add 0～+ alternating voltage of 170V drives test.

And this laminate type piezoelectric element carries out Continuous Drive and is tested to 1 * 10 ⁹Inferior, at this moment, be shown fraction defective with producing bad numerical table.In addition, for the metal 14 that is dispersed in the inert layer 12, analyze 3 places by EPMA on the arbitrary section of inert layer 12, investigation has or not the dispersion of metal.On the other hand, the amount of metal 14 is to take out sample at any 3 places of inert layer 12 in the inert layer 12, and each sample is carried out the ICP luminesceence analysis, gets the mean value of the amount of calculating.The result is as shown in table 3.In addition, the fusing point of the dispersed metal shown in the table 3 is represented the ratio of the fusing point of dispersed metal with respect to the firing temperature of laminated body 10a with respect to the ratio of firing temperature.

Table 3-1

[0198]Table 3-2

Find from table 3, the lamination-type piezo actuator of the specimen coding 1 of comparative example, owing to electrode is set at inert layer, so in the Continuous Drive process of the test, because the generation crack, interface of the stress that the vibration of laminate type piezoelectric element produces and electrode in inert layer and active portion, fraction defective uprises.

Relative therewith, the lamination-type piezo actuator of the specimen coding 2～21 of the embodiment of the invention 3, because dispersed metal in inert layer 12, burn till stress mitigation and the homogenizing that between inert layer 12 and active portion 11, produces when shrinking so can make, and, also can suppress the crack of inert layer 12 etc. under high voltage, long-time continuous are used, superior durability is so fraction defective reduces.

In addition, specimen coding 2,3 because the melting point metal that constitutes electrode layer 8 is obviously than the firing temperature height of laminated body 10a, thus difficult in inert layer 12 dispersed metal 14, the above-mentioned effect of difficult performance.

In addition, specimen coding 17, because the dispersion amount of metal 14 surpasses 1.0 quality % with respect to inert layer 12, so the insulating properties deterioration of inert layer 12 causes insulation breakdown, fraction defective uprises.

On the other hand, specimen coding 4～16,18～21 is because the dispersion amount of metal 14 is 0.001～1.0 quality % with respect to inert layer 12, so bring into play above-mentioned effect easily.Especially, above-mentioned dispersion amount be 0.1 quality % and metal 14 by silver and palladium constitutes, promptly, metal 8 contain the metal that constitutes internal electrode 2 specimen coding 11～13,16, reach 18～21, because guaranteeing the insulating properties of inert layer 12 and metal 14 spreads to inert layer 12 easily, so use in high voltage, long-time continuous, also can suppress the crack of inert layer 12 etc., and superior durability, so fraction defective obviously reduces.

Claims (2)

1. the manufacture method of a laminate type piezoelectric element is characterized in that, comprising:

The both ends of the surface of the living laminated body that forms at alternative stacked piezoelectrics raw cook and conductor layer form piezoelectric material layer;

On described piezoelectric material layer, form metal level;

After the described living laminated body that has formed described piezoelectric material layer and described metal level is burnt till, remove described metal level,

The fusing point of described metal level is the temperature below 1.6 times of the firing temperature of described living laminated body.

2. the manufacture method of laminate type piezoelectric element according to claim 1 is characterized in that:

Described metal level is formed thickness below the 5mm.

Images