CN101504966A - Multilayer piezoelectric device and ejection apparatus - Google Patents
Multilayer piezoelectric device and ejection apparatus Download PDFInfo
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- CN101504966A CN101504966A CNA2008101903503A CN200810190350A CN101504966A CN 101504966 A CN101504966 A CN 101504966A CN A2008101903503 A CNA2008101903503 A CN A2008101903503A CN 200810190350 A CN200810190350 A CN 200810190350A CN 101504966 A CN101504966 A CN 101504966A
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Abstract
A multi-layer piezoelectric element having excellent durability in which the amount of displacement does not change even after subjecting to continuous operation over a long period of time under a high voltage and a high pressure is provided. The multi-layer piezoelectric element comprises a stack formed by stacking piezoelectric layers and internal electrodes alternately one on another and external electrodes formed on a first side face and on a second side face of the stack, wherein one of the adjacent internal electrodes is connected to the external electrode formed on the first side face and the other internal electrode is connected to the external electrode formed on the second side face. The external electrode is composed of the porous electric conductor which comprises conductive material and glass and is configured to a three-dimensional network structure.
Description
The application is based on dividing an application of application number is 200480027657.1, denomination of invention for " multi-layer piezoelectric element ", the applying date is on September 22nd, 2004 patent application.
Technical field
The present invention relates to multi-layer piezoelectric element and injection apparatus, for example relate to the multi-layer piezoelectric element and the injection apparatus of stack-up type piezo-activator in driving element that the precision positioning device that is used in piezoelectric transformer or automotive fuel injection apparatus, Optical devices etc. or vibration prevent usefulness etc. etc.
Background technology
All the time, as multi-layer piezoelectric element, the known stack-up type piezo-activator that has alternately lamination piezoelectrics and internal electrode to form.In the stack-up type piezo-activator, be categorized as slug type simultaneously, with these 2 types on the accumulation type of alternately lamination piezoelectricity chinaware and internal electrical pole plate, if consider from the aspect that lower voltage, manufacturing cost reduce, then the stack-up type piezo-activator of slug type is favourable for thin layerization simultaneously, so shown its superiority.
Fig. 6 is the figure of the existing stack-up type piezo-activator of expression, and in this actuator, piezoelectrics 51 and internal electrode 52 be lamination and form laminate 53 alternately, and the both ends of the surface lamination on its lamination direction has inert layer 55.Internal electrode 52, the end face of one side alternately exposes about the side of laminate 53, and the side of the laminate 53 that exposes in the end of this internal electrode 52 is formed with outer electrode 70.The opposing party's of internal electrode 52 end is coated by insulator 61, with outer electrode 70 insulation.
Again, the stack-up type piezo-activator of while slug type, temperature with regulation is carried out after the degreasing the lamination formed body, obtain laminate by sintering, described lamination formed body by by the printing of lamination regulation sheet number on the powders calcined of piezoelectrics and the ceramic green sheet that organic bond constitutes in silver-palladium powder, add and mixed the sheet that internal electrode paste that adhesive forms forms and obtain.
Its sintering temperature of existing piezoelectrics must be 1200～1300 ℃ a temperature, so the high silver-palladium alloy of ratio of the palladium of high price uses as internal electrode.But, the technology of low-temperature sinteringization is in development recently, having developed can be at the piezoelectrics of the temperature sintering about 1100 ℃, even but in this case if consider the fusing point of internal electrode, then also must be the silver-palladium alloy of silver-colored ratio 70% weight, palladium ratio 30% weight.
Again, all the time, outer electrode is with silver 83～99% weight (silver 71～95% quality) and remainder glass powder 1～17% weight (glass powder 5～29% quality), be coated on the side of laminate 53 with the conductive paste that is made of organic principle, and form (for example, with reference to patent documentation 1) in the mode of 500～1000 ℃ of following sintering.
Patent documentation 1: the spy opens the 2000-40635 communique
Patent documentation 2: open clear 60-99522 communique in fact
Patent documentation 3: the spy opens clear 61-133715 communique
Patent documentation 4: open flat 1-130568 communique in fact
Summary of the invention
But, in existing stack-up type piezo-activator, under the situation that long-time continuous under high electric field, the high pressure drives, following problem is arranged: outer electrode 70 can not be followed the flexible of laminate 53 and be broken, perhaps externally cause that contact is bad between electrode 70 and the internal electrode 52, voltage can not supply in the piezoelectrics 51 of a part, thereby displacement properties changes in driving.
Again, in recent years, in small-sized stack-up type piezo-activator, in order under bigger pressure, to guarantee bigger addendum modification, carried out applying higher electric field, the operation that its long-time continuous is driven, but only conductive paste is coated to behind the side of laminate 53 sintering again, have following problem: outer electrode 70 is not flexible, can not follow flexible to the lamination direction of laminate 53, thereby internal electrode 52 produces with being connected releasing of outer electrode 70 and peels off, externally crack on the electrode 70 again and break, voltage can not supply to the piezoelectrics 51 of a part, thereby displacement properties changes in driving.
And then, because include the high palladium of the cost of 30% weight, so high this problem of the cost of goods is arranged.
Therefore, even the object of the present invention is to provide a kind ofly under the situation that long-time continuous under high electric field, the high pressure drives, outer electrode and internal electrode are also and do not break the multi-layer piezoelectric element of good endurance.
The multi-layer piezoelectric element of first aspect present invention, it comprise piezoelectric body layer and internal electrode alternately the laminate that forms of lamination, be formed at first side of this laminate and the outer electrode on second side respectively, a side internal electrode is connected in outer electrode in first side in the internal electrode of adjacency, and the opposing party's internal electrode is connected in outer electrode in second side;
Described outer electrode is by containing electric conducting material and glass, and the porous matter electric conductor that constitutes the three-dimensional network structure constitutes.
In the first such multi-layer piezoelectric element, because outer electrode is by containing electric conducting material and glass, and the porous matter electric conductor that constitutes the three-dimensional network structure constitutes, so have flexibility.Even for example laminate be actuator body when driving under situation flexible on the lamination direction, outer electrode also can followed the flexible of laminate, thereby can prevent to produce bad these problems of contact of broken string or the outer electrode and the internal electrode of outer electrode.
Thereby, multi-layer piezoelectric element according to first aspect present invention, because outer electrode can absorb the flexible stress that produces because of laminate fully, even so under the situation of high speed long-time continuous running under high electric field, the high pressure, also can suppress the broken string of outer electrode and internal electrode, thereby the multi-layer piezoelectric element with high reliability can be provided.
In the multi-layer piezoelectric element of first aspect present invention, be preferably described outer electrode and partly be engaged on described first side and described second side again.Like this, partly be engaged in the laminate side, just can more can flexibly absorb with respect to the contraction of laminate and the stress that produces than situation with whole joint by making outer electrode.
And then the electric conducting material that the multi-layer piezoelectric element of first aspect present invention is preferably outer electrode is principal component with silver.Like this, be the low silver of Young's modulus by making the electric conducting material that forms outer electrode, just can more flexibly absorb the flexible stress that produces because of laminate.Again, be silver, just become easily with the diffusion bond of the silver-palladium alloy that usually uses as the electric conducting material of internal electrode, thereby can connect outer electrode and internal electrode more firmly by making the electric conducting material that constitutes outer electrode.
And then the multi-layer piezoelectric element of first aspect present invention is preferably the softening point of the glass that constitutes outer electrode below the fusing point of the electric conducting material that constitutes described outer electrode.Like this, the sintering temperature of outer electrode can be done to become below the fusing point of electric conducting material and the temperature more than the softening point of glass ingredient, can prevent the aggegation of electric conducting material, thereby can obtain the sufficient joint strength that produces because of glass ingredient.
Again, it is principal component with Ag that the multi-layer piezoelectric element of first aspect present invention is preferably the metal ingredient that internal electrode contains, and contains more than at least a in following Pd of 15% weight and the Pt family metal.By making the Pd that internal electrode contains and the amount of Pt family metal is below 15% weight, the composition that just can reduce internal electrode and outer electrode is poor, so the counterdiffusion mutually of the metal between internal electrode and outer electrode is good, thereby can improve the reliability that engages between internal electrode and outer electrode, improve durability.
The multi-layer piezoelectric element of second aspect present invention, it comprise piezoelectric body layer and internal electrode alternately the laminate that forms of lamination, be formed at first side of this laminate and the outer electrode on second side respectively, one side's of the internal electrode of adjacency internal electrode is connected in outer electrode in first side, and the opposing party's internal electrode is connected in outer electrode in second side;
Described internal electrode and described outer electrode include silver respectively,
In establishing described internal electrode, be X (%) with respect to the silver-colored weight rate of electric conducting material integral body,
If in the described outer electrode, when being Y (%) with respect to the weight rate of the silver of the total weight of electric conducting material and glass,
To satisfy the mode of X ≧ 85 and 0.9 ≦ X/Y ≦ 1.1, set the silver-colored ratio of described internal electrode and described outer electrode.
If as described in as the multi-layer piezoelectric element of this second aspect, setting internal electrode with as described in the silver-colored ratio of outer electrode, then can suppress the use amount of the palladium of high price, so the multi-layer piezoelectric element of cheapness can be provided.
Again, because constitute the weight rate of the silver in the electric conducting material of described internal electrode, with the weight rate of silver in the described outer electrode about equally, so when being sintered in described outer electrode on the described laminate, promoted the counterdiffusion mutually of the silver in silver and the described internal electrode in the described outer electrode, thereby described internal electrode becomes possibility with firm the engaging of described outer electrode, even at high electric field, under the situation that long-time continuous drives under the high pressure, described outer electrode and described internal electrode also and do not break, thereby can have good durability.
Again, in the multi-layer piezoelectric element of second aspect present invention, be preferably described internal electrode and include piezoelectric, when the silver-colored weight rate with respect to the total weight that includes described piezoelectric in establishing described internal electrode is Z (%), satisfy 0.7 ≦ Z/Y ≦ 1.0.
If in described internal electrode, contain piezoelectric like this, then during the burning till of the electric conducting material in described internal electrode, piezoelectrics are sintering side by side, just can improve the bond strength of described internal electrode and described piezoelectrics, thereby can improve the durability of described laminate.
Again, because by so that the silver-colored weight rate in the described internal electrode satisfies the mode of 0.7 ≦ Z/Y ≦ 1.0 sets, silver-colored weight rate in the described internal electrode and the silver-colored weight rate in the described outer electrode are just about equally, so when the described outer electrode of sintering, promoted the counterdiffusion mutually of the silver in silver and the described internal electrode in the described outer electrode, thereby described internal electrode becomes possibility with firm the engaging of described outer electrode.With this,, also can prevent the broken string of the contact portion of described outer electrode and described internal electrode even under the situation of high-speed driving.
Again, in the multi-layer piezoelectric element of second aspect present invention, being preferably described outer electrode is made of the porous matter electric conductor that constitutes the three-dimensional network structure, with this, even when driving under the flexible situation of lamination direction, because described outer electrode is flexible, also becomes possibility so described outer electrode is followed this situation with respect to the flexible of described laminate, thereby can prevent that the contact of the broken string of described outer electrode or described outer electrode and described internal electrode is bad etc.
Again, in the multi-layer piezoelectric element of second aspect present invention, be preferred for the glass in the described outer electrode softening point (℃) be the fusing point that constitutes the electric conducting material of described internal electrode (℃) below 4/5.
If set the softening point of the glass that is used for outer electrode like this, then can be and carry out the sintering of described outer electrode under than the high temperature of the softening point of described glass in the temperature fully lower than the fusing point of the electric conducting material that constitutes described internal electrode, so can prevent the aggegation of the electric conducting material of described internal electrode and described outer electrode, and make the sufficient diffusion bond of the electric conducting material of electric conducting material in the described internal electrode and described outer electrode become possibility, thereby can have the strong bond strength that produces because of softening glass.
Again, in the multi-layer piezoelectric element of the present invention aspect first and second, in order to absorb the flexible stress that produces when driving effectively, prevent the breakage of outer electrode, the voidage that is preferably described outer electrode is 30～70% volumes.
Again, in the multi-layer piezoelectric element of the present invention aspect first and second, being preferably the glass that constitutes described outer electrode is noncrystalline.If constituting the glass of described outer electrode is noncrystalline, then can more reduce Young's modulus, so can be suppressed at the crackle that produces on the described outer electrode etc. than crystalloid.
The multi-layer piezoelectric element of third aspect present invention, comprise piezoelectric body layer and internal electrode alternately the laminate that forms of lamination be formed at first side of this laminate and the outer electrode on second side respectively, one side's of the internal electrode of adjacency internal electrode is connected in outer electrode in first side, and the opposing party's internal electrode is connected in outer electrode in second side;
Described internal electrode is by being principal component with silver and including palladium or at least a electric conducting material of platinum constitutes, described again outer electrode is made of the electric conducting material and the glass that with silver are principal component, and is bigger than the silver-colored ratio of the internal electrode electric conducting material of laminate inside with near the silver-colored ratio of the internal electrode electric conducting material connecting portion of outer electrode.
In the multi-layer piezoelectric element of the present invention of above formation, the electric conducting material of internal electrode becomes more firm with being connected of the electric conducting material of outer electrode, even under the situation of high electric field Continuous Drive, can prevent that also the connecting portion that produces outer electrode and internal electrode from peeling off this problem.
Promptly, for make with silver be principal component outer electrode engage firm, with the connecting portion of outer electrode near, make the silver-colored ratio of internal electrode electric conducting material bigger than the silver-colored ratio of laminate inside, with this, the principal component that can the make the outer electrode electric conducting material i.e. concentration of the silver in silver and the internal electrode electric conducting material is approaching, so the mutually counterdiffusion of the joint of outer electrode and internal electrode by silver becomes reliable.
Promptly, because the concentration of the silver near the electric conducting material of the internal electrode the connecting portion of formation and outer electrode and the concentration of the silver in the outer electrode are about equally, so when being sintered in described outer electrode on the described laminate, promoted the counterdiffusion mutually of the silver in silver and the described internal electrode in the described outer electrode, thereby described internal electrode becomes possibility with firm the engaging of described outer electrode, even at high electric field, under the situation that long-time continuous drives under the high pressure, described outer electrode and described internal electrode also and do not break, thereby can have good durability.
Again, in the multi-layer piezoelectric element of third aspect present invention, be preferably along with near outer electrode, the ratio of the silver in the internal electrode electric conducting material increases gradually.If form the concentration gradient of silver so continuously, then can establish engaging of stable internal electrode and internal electrode and outer electrode.
In the multi-layer piezoelectric element of third aspect present invention, be preferably outer electrode and internal electrode to be formed with the mode diffusion bond of neck again.If make like this,, also can prevent the spark of contact portion of described internal electrode and outer electrode or broken string etc. even then under the situation of big electric current high-speed driving that flows.
Again, in the multi-layer piezoelectric element of third aspect present invention, the silver-colored ratio that is preferably in the internal electrode electric conducting material is more than 85% weight.If make like this, then can improve the concentration of the silver in the internal electrode, thereby can make reliable based on the diffusion bond of silver with being connected of outer electrode.In addition, the silver-colored ratio in the so-called internal electrode electric conducting material is meant the silver-colored ratio in the laminate inside of the silver-colored constant rateization of internal electrode.
In the multi-layer piezoelectric element of third aspect present invention, be preferably below 80% of laminate top layer side that glass ingredient in the outer electrode is present in the thickness of outer electrode substantially again.
Promptly, if make glass ingredient in the outer electrode be present in below 80% of laminate top layer side of the thickness of outer electrode substantially, then externally the atmospheric side skin section of electrode in fact only to exist with silver be the electric conducting material of principal component, even thereby lead is being fastened under the situation of described outer electrode with scolding tin, also can provide the scolding tin wetting quality good external electrode surface.
In the multi-layer piezoelectric element of third aspect present invention, be preferably in the glass ingredient in the electrode externally and include lead oxide or bismuth oxide again.As including lead oxide or bismuth oxide in the glass ingredient in the electrode externally, then can make outer electrode firm with engaging of piezoelectrics.
Again,, be preferably to the multi-layer piezoelectric element of the third aspect in the present invention first: the end diffusion bond of described outer electrode and described internal electrode, the electric conducting material composition of internal electrode is spread in the outer electrode, thereby forms neck.Like this, can engage electric conducting material and the internal electrode that constitutes outer electrode securely by diffusion bond.With this,, also can prevent local pyrexia, spark, the broken string of the contact portion of described internal electrode and described outer electrode even under the situation of big electric current high-speed driving that flows.
, to the multi-layer piezoelectric element of the third aspect, be preferably in the piezoelectricity side of described outer electrode skin section and be formed with the glass enriched layer in the present invention first again.If be formed with the glass enriched layer in the piezoelectricity side of described outer electrode skin section like this, then can improve the bond strength of described outer electrode and described laminate.
To the multi-layer piezoelectric element of the third aspect, be preferably the thin thickness of the thickness of described outer electrode in the present invention first than the described piezoelectrics that constitute described laminate again.If set the thickness of described outer electrode like this, then the hardness of described outer electrode diminishes, when described laminate drives flexible when, can make the load on the junction surface of described outer electrode and described internal electrode little, so it is bad to suppress the contact at described junction surface.
Again, in the present invention first to the multi-layer piezoelectric element of the third aspect, be preferably: in described first side, between the end of described the opposing party's internal electrode and described outer electrode, be formed with groove, in this groove, be provided with insulator,, between the end of a described side's internal electrode and described outer electrode, be formed with groove in described second side, be provided with insulator in this groove, described insulator is lower than described piezoelectrics Young's modulus.
If constitute in this wise, then can guarantee the insulation of described internal electrode and described outer electrode, and flexible can follow the driving of described laminate time of the described insulator in the groove and being out of shape, so can prevent near the generation of the crackle etc. the groove, can reduce the generation of stress again.
Again, in the present invention first to the multi-layer piezoelectric element of the third aspect, the conductivity accessory that can constitute by the conductive adhesive of net that is embedded with metal or cancellous metallic plate in the outer surface setting of described outer electrode, if make in this wise, even then under situation with the described laminate of big electric current high-speed driving, also can make described big electric current flow to the conductivity accessory, so can prevent the broken string that the local pyrexia because of described outer electrode causes, thereby can improve durability significantly.
Again, by net or the cancellous metallic plate that in described conductive adhesive, is embedded with metal, the crackle of the flexible conductive adhesive that produces in the time of just can preventing the driving because of described laminate etc.
And then, in above-mentioned multi-layer piezoelectric element, be preferably conductive adhesive and constitute by the polyimides that is dispersed with electroconductive particle.By the bonding composition that makes conductive adhesive is the high polyimides of thermal endurance, even described conductive adhesive also can be kept high-adhesive-strength when high temperature uses.
And then the electroconductive particle that is preferably conductive adhesive is a silver powder.Use the silver powder lower as electroconductive particle, just can reduce the resistance value of this conductive adhesive, even under the situation of big current drives that flows, also can prevent local pyrexia with this than resistance.And then, can make the degree of polymerization between electroconductive particle firm, thereby can further improve the intensity of this conductive adhesive, consider that from this reason described electroconductive particle is preferably the aspheric particle of laminar or needle-like etc.
Description of drawings
Figure 1A is the stereogram of the multi-layer piezoelectric element of embodiments of the present invention one to three;
Figure 1B is the sectional arrangement drawing of the A-A ' line of Figure 1A;
Fig. 2 A is a profile of representing the part of Figure 1B enlargedly;
Fig. 2 B is the profile of the part of presentation graphs 2A enlargedly;
Fig. 2 C is the cross sectional photograph of the part identical with Fig. 2 B;
Fig. 3 A is in the manufacture method of multi-layer piezoelectric element of the present invention, the profile after the side forms groove;
Fig. 3 B is in the manufacture method of multi-layer piezoelectric element of the present invention, the profile after the side forms conductive paste 21;
Fig. 3 C is in the manufacture method of multi-layer piezoelectric element of the present invention, the profile after the side forms outer electrode 4;
Fig. 4 A is the stereogram that the outer surface that is illustrated in outer electrode is formed with the multi-layer piezoelectric element of the present invention of conductivity accessory;
Fig. 4 B is the profile of Fig. 4 A;
Fig. 4 C is the profile of the part of presentation graphs 4B enlargedly;
Fig. 5 is the profile of formation of the injection apparatus of expression embodiments of the present invention four;
Fig. 6 is the profile of existing stack-up type piezo-activator;
Fig. 7 is the curve chart of the silver-colored ratio in the internal electrode electric conducting material of representing in the embodiments of the invention four.
Symbol description
1 piezoelectrics
2 internal electrodes
3 insulators
4 outer electrodes
The 4b neck
6 leads
10 laminates
31 accommodating containers
33 spray-holes
35 valves
43 piezo-activators
Embodiment
Execution mode one
Figure 1A is the stereogram of the multi-layer piezoelectric element (stack-up type piezo-activator) of embodiments of the present invention one, and Figure 1B is the sectional arrangement drawing of the A-A ' line in Figure 1A.
The stack-up type piezo-activator of present embodiment one, shown in Figure 1A, 1B, the laminate 10 of the square column that constitutes by a plurality of piezoelectrics 1 of lamination alternately and a plurality of internal electrodes 2, with to be formed at outer electrode 4 formations on its side every one deck and internal electrode 2 ways of connecting.Particularly, constitute as follows: on the side that is formed with outer electrode 4, coat the end of internal electrode 2 every one deck, not the end and outer electrode 4 conductings of the internal electrode 2 that coats by insulator 3 by insulator 3.Again, outer electrode 4 adopts by the electric conducting material and the glass porous matter electric conductor that constitute, that have the three-dimensional network structure that with silver are principal component, is connected with lead 6 on each outer electrode 4.In addition, in laminate 10, having marked the part that symbol 9 represents is the inert layer that is not formed with internal electrode.
Between piezoelectrics 1, dispose internal electrode 2, this internal electrode 2 forms with metal materials such as silver-palladiums, be the electrode that is used on each piezoelectrics 1, applying the voltage of regulation, on piezoelectrics 1, cause displacement because of producing with the corresponding reciprocal piezoelectric effect of the voltage that is applied.
Again, be formed with the groove of width 30～200 μ m of the degree of depth 30～500 μ m, lamination direction every one deck ground in the side of laminate 10, in this groove, be filled with the glass lower, epoxy resin, polyimide resin, polyamide-imide resin, silicon rubber etc., thereby form insulator 3 than piezoelectrics 1 Young's modulus.Firm in order to make with engaging of laminate 10, this insulator 3 be preferably by with respect to the displacement of laminate 10 and low material, the particularly silicon rubber etc. of modulus of elasticity of following constitute.
Opposed 2 sides at laminate 10 have engaged outer electrode 4 respectively, are electrically connected the internal electrode 2 of lamination on this outer electrode 4 every one deck.This outer electrode 4 functions as follows: will the necessary voltage common land of piezoelectrics 1 displacement be supplied on each internal electrode 2 that is connected to utilizing reciprocal piezoelectric effect.
And then, externally utilize scolding tin to be fixedly connected with lead 6 on the electrode 4.This lead 6 functions as follows: outer electrode 4 is connected to outside voltage supply unit.
And, in present embodiment one, it is characterized in that outer electrode 4 is by containing electric conducting material and glass, and the porous matter electric conductor that constitutes the three-dimensional network structure as shown in Figure 2 constitutes.At this, the three-dimensional network structure is not to mean externally to have so-called spherical this state of space on the electrode 4, and be meant following state: in order to constitute the conducting material powder and the glass powder of outer electrode 4 at lower temperature sintering, and carry out constantly at sintering, have the space with to a certain degree connecting state, the conducting material powder that constitutes outer electrode 4 links three-dimensionally, engages with glass powder.In addition, Fig. 2 A has amplified the part of the section shown in Figure 1B and the profile that obtains, and Fig. 2 B is the further profile of the part of presentation graphs 2A enlargedly.
In execution mode one, like this by constituting with electric conducting material and glass and constituting the outer electrode 4 and internal electrode 2 diffusion bond that the porous matter electric conductor of three-dimensional network structure constitutes, again, because outer electrode 4 partly engages with laminate 10, even so under the situation of long-time continuous drive actuator under high electric field, the high pressure, also can prevent following problem: externally cause spark between electrode 4 and the internal electrode 2, or outer electrode 4 is peeled off or broken from laminate 10.In present embodiment one, sintering by the conductive paste that under lower temperature, carries out constituting by electric conducting material that forms outer electrode 4 and glass, just outer electrode 4 integrally can be made to become porous plastid, can partly be engaged in the side of laminate 10.
The electric conducting material that constitutes outer electrode 4 is from the flexible stress this point that produces of abundant absorption because of actuator, is preferably low silver-colored of Young's modulus or is the alloy of principal component with silver.
Again, in present embodiment one, shown in Fig. 2 B, be formed with neck 4b, can realize firm being connected of internal electrode 2 and outer electrode 4 in internal electrode 2 ends that are connected with outer electrode 4.Neck 4b forms by the electric conducting material of outer electrode 4 and the electric conducting material diffusion bond of internal electrode 2.
If be formed with neck in the internal electrode end like this, this neck is embedded in the outer electrode, even under big electric current, the situation of then in multi-layer piezoelectric element, flowing, also can prevent the local pyrexia on the junction surface of internal electrode and outer electrode with high-speed driving.
And then in present embodiment one, being preferably voidage in the outer electrode 4 and being the ratio that space 4a externally occupied in the electrode 4 is 30～70% volumes.With this, can flexibly bear the flexible stress that produces because of actuator.That is, externally the voidage in the electrode 4 is than under the little situation of 30% volume, and outer electrode 4 can not bear the flexible stress that produces because of actuator, thereby the possibility of outer electrode 4 broken strings is arranged.On the other hand, externally the voidage in the electrode 4 is than under the 70% bulky situation, and it is big that the resistance value of outer electrode 4 becomes, thereby thereby has when the big electric current that flows outer electrode 4 to cause the possibility of local pyrexia broken string.
Again, in present embodiment one, the softening point that constitutes the glass ingredient of outer electrode 4 is done to become below the fusing point of the electric conducting material that constitutes outer electrode 4.This is for below the fusing point of the sintering temperature of outer electrode 4 being made become electric conducting material and the temperature more than the softening point of glass ingredient.With this, just can so prevented the aggegation of electric conducting material, can make to become porous plastid carrying out sintering more than the softening point of glass ingredient and under the temperature below the fusing point of electric conducting material, can carry out sintering with sufficient joint strength.
Again, in present embodiment one, the glass ingredient that constitutes outer electrode 4 is a noncrystalline.With this, outer electrode 4 can absorb the flexible stress that produces because of actuator, thereby can prevent the generation of crackle etc.
Again, in present embodiment one, the thickness that is preferably outer electrode 4 makes to become the thin thickness than the piezoelectrics 1 that constitute laminate 10.With this, outer electrode 4 has suitable intensity with respect to the lamination direction of laminate 10, thereby can prevent the increase of the load on the contact of outer electrode 4 and internal electrode 2 when actuator is flexible, can prevent that contact is bad.
The manufacture method of multi-layer piezoelectric element of the present invention then, is described.At first, the adhesive that constitutes with the powders calcined of piezoelectric ceramic such as PZT, with organic polymer, mix with DBP (dibutyl phthalate), DOP plasticizer such as (dioctyl phthalates) and to make slurry, utilize the well-known band method of forming of scraping the skill in using a kitchen knife in cookery or stack method etc. this slurry to be made as the ceramic green sheet that constitutes piezoelectrics 1 by propylene base system, butyral system etc.
Then, in silver-palladium powder, add mixed adhesive, plasticizer waits and makes conductive paste, utilizes screen printing etc. its thickness with 1～40 μ m to be printed in the upper surface of described each raw cook.
Then, at a plurality of raw cooks that are printed with conductive paste of upper surface lamination, with regard to this laminate, after carrying out the unsticking mixture under the temperature of regulation,, just produce laminate 10 by at 900～1200 ℃ of following sintering.
In addition, laminate 10 is not limited to make with above-mentioned manufacture method, as long as can make the laminate 10 that the alternately a plurality of piezoelectrics of lamination and a plurality of internal electrode form, then can utilizing arbitrarily, manufacture method forms.
Afterwards, as shown in Figure 3A, utilize cutter sweep etc. to form groove every one deck in the side of laminate 10.
And then, by silver powder 80～97% volumes, particle diameter 0.1～10 μ m, with 3～20% volumes, remainder particle diameter 0.1～10 μ m, with silicon be principal component, softening point is to add adhesive in the mixture that constitutes of 450～800 ℃ glass powder to make silver-colored glass conductive paste.Should be configured as tabular and dry (solvent is dispersed) by silver glass conductive paste.The green density of plate 21 is controlled to be 6～9g/cm
3Shown in Fig. 3 B, the outer electrode that this plate 21 is needed on the laminate 10 that is formed with groove forms face, the temperature higher and the temperature below the silver point (965 ℃) and sintering temperature than the softening point of glass (℃) the temperature below 4/5 under carry out sintering.With this, shown in Fig. 3 C, use the disappearance of dispersing of adhesive ingredients in the plate 21 that silver-colored glass conductive paste makes, thereby form the outer electrode 4 that constitutes by the porous matter electric conductor that constitutes the three-dimensional network structure.
Again, if the sintering temperature of outer electrode (℃) be laminate sintering temperature (℃) the temperature below 4/5, then can make the diffusing capacity of glass ingredient in laminate that constitutes outer electrode an amount of, thereby the bond strength that can prevent laminate and outer electrode reduce.
Particularly, in order to form the outer electrode 4 of three-dimensional network structure, it is very important that the green density of plate 21 is controlled to be 6～9g/cm3.The green density of plate 21 utilizes Archimedes's method to measure.Particularly, for the voidage with outer electrode 4 is 30～70%, preferably making green density is 6.2～7.0g/cm
3
When the sintering of this silver glass conductive paste, externally form space 4a in the electrode 4, and silver in the silver-colored glass conductive paste and the silver-palladium alloy diffusion bond in the internal electrode 2, neck 4b formed, again, this outer electrode 4 partly is engaged in the laminate side.Among the neck 4b, Pd electrode 2 diffusions internally form silver-palladium alloy.
In addition, the sintering temperature of described silver-colored glass conductive paste is preferably 550～700 ℃.If be set at this scope, then form effective neck 4b, silver in the silver-colored glass conductive paste and internal electrode 2 diffusion bond, again, the space in the outer electrode 4 is remaining effectively, and then, engage outer electrode 4 and laminate 10 lateral parts.Again, the softening point of the glass ingredient in the silver-colored glass conductive paste is preferably 500～700 ℃.
Sintering temperature than 700 ℃ of high situations under, the sintering of the silver powder of silver glass conductive paste exceedingly carries out, thereby can not form the porous matter electric conductor that constitutes effective three-dimensional network structure, it is too fine and close that outer electrode 4 becomes, consequently the Young's modulus of outer electrode 4 becomes too high, can not absorb the stress when driving fully, thereby the possibility of outer electrode 4 broken strings is arranged.Preferably, carry out sintering 1.2 times of the softening point of glass under with interior temperature.
On the other hand, sintering temperature be than 550 ℃ of low situations under, between internal electrode 2 ends and outer electrode 4, can not carry out diffusion bond fully, thus neck 4b can not be formed, thus the possibility that causes spark when driving between the internal electrode 2 and outer electrode 4 is arranged.
In addition, the thickness of the plate 21 of silver-colored glass conductive paste is preferably the thin thickness than piezoelectrics 1.Consider from the flexible this point of following brake, more preferably below the 50 μ m.
Making the silver powder in the silver-colored glass conductive paste 21 is 80～97% volumes, the glass powder of remainder be 3～20% volumes be because, under the situation that silver powder is lacked than 80% volume, it is many that glass ingredient relatively becomes, when carrying out sintering, just externally form space 4a effectively or this outer electrode 4 partly can not be engaged in laminate 10 sides in the electrode 4, on the other hand, silver powder than more than 97% situation under, glass ingredient relatively tails off, outer electrode 4 dies down with the bond strength of laminate 10, thereby outer electrode 4 is peeled off from laminate 10.
Again, the glass ingredient that constitutes outer electrode 4 uses silex glass, soda-lime glass, plumbous alkali silicate glasses, aluminium oxide borosilicate glass, borosilicate glass, alumina silicate glass, borate glass, phosphate glass etc.
For example, as borosilicate glass, can use and contain SiO
240～70% quality, B
2O
32～30% quality, Al
2O
3Such alkaline earth metal oxide aggregate 0～10% quality of 0～20% quality, MgO, CaO, SrO, BaO, the glass of alkali metal oxide 0～10% quality.Use the such glass of the ZnO in above-mentioned borosilicate glass, include 5～30% quality also harmless again.ZnO has the effect of the processing temperature that reduces borosilicate glass.
As phosphate glass, can use to include P again,
2O
540～80% quality, Al
2O
30～30% quality, B
2O
30～30% quality, ZnO0～30% quality, alkaline earth metal oxide 0～30% quality, the such glass of alkali metal oxide 0～10% quality.
As lead glass, can use to include PbO30～80% quality, SiO again,
20～40% quality, Bi
2O
30～30% quality, Al
2O
30～20% quality, ZnO 0～30% quality, alkaline earth metal oxide 0～30% quality, the such glass of alkali metal oxide 0～10% quality.
Then, the laminate 10 that will be formed with outer electrode 4 impregnated in silicone rubber solution, and utilizes silicone rubber solution is carried out vacuum degassing, comes at the inner filled silicon rubber of the groove of laminate 10, from silicone rubber solution pull out laminate 10, at the side of laminate 10 coating silicon rubber thereafter.The described silicon rubber of the side that be filled in groove inside and be coated on laminate 10 solidified thereafter.
By lead 6 be connected in outer electrode 4 on, finish of the present invention multi-layer piezoelectric element thereafter.
Then, utilize lead 6 on pair of external electrodes 4, to apply the direct voltage of 0.1～3kV/mm,, just finish with this stack-up type piezo-activator as goods to laminate 10 processing that polarizes.If the lead 6 of this stack-up type piezo-activator is connected in outside voltage supply unit, utilize 4 pairs of internal electrodes 2 of lead 6 and outer electrode to apply voltage, then each piezoelectrics 1 is because of reciprocal piezoelectric effect displacement significantly, with this for example as to the automotive fuel injection valve of engine spray fueling and bring into play its function.
Because by containing with silver is that the outer electrode 4 that the electric conducting material of principal component and glass and the porous matter electric conductor that constitutes the three-dimensional network structure constitute partly is connected in laminate 10 sides, even so the multi-layer piezoelectric element of above formation under the situation of Continuous Drive actuator under the high electric field, also can absorb the stress that produces when outer electrode 4 drives fully.Thereby, can prevent from externally to cause spark between the electrode 4 and internal electrode 2, perhaps outer electrode 4 these problems of broken string, thus the brake of high reliability can be provided.
Again, in present embodiment one, the metal ingredient that internal electrode 2 is contained be preferably with silver be principal component and contain Pd below 15% weight and Pt family metal in more than one.By making the Pd that internal electrode 2 contained and the amount of Pt family metal is below 15% weight, it is poor with the composition of outer electrode 4 just can to reduce internal electrode 2, so the counterdiffusion mutually of the metal between internal electrode 2 and the outer electrode 4 is good, thereby can improve the reliability that engages between internal electrode 2 and the outer electrode 4, improve durability.By in internal electrode 2, containing the powder with the roughly the same composition of laminate 10 aptly, just can improve the engaging force of the internal electrode 2 in the laminate 10 again.
Multi-layer piezoelectric element of the present invention is not limited to above-mentioned multi-layer piezoelectric element, as long as just can carry out all changes in the scope that does not break away from main idea of the present invention.
In above-mentioned example, the example that is formed with outer electrode 4 in the opposed side of laminate 10 has been described again.But in the present invention, for example forming pair of external electrodes in the side that the neighbour establishes also can.
Execution mode two
The multi-layer piezoelectric element of embodiment of the present invention two (stack-up type piezo-activator) is in the multi-layer piezoelectric element of execution mode one, outer electrode 4 and internal electrode 2 following formations.
In the stack-up type piezo-activator of present embodiment two, outer electrode 4 is made of the electric conducting material and the glass that with silver are principal component, and described internal electrode 2 includes electric conducting material and piezoelectric.
And, silver-colored weight rate in the electric conducting material of establishing internal electrode 2 is X (%), the silver-colored weight rate that includes in the internal electrode 2 of electric conducting material and piezoelectric is Z (%), when the silver-colored weight rate in the outer electrode 4 was Y (%), each ratio was set in the mode that satisfies X ≧ 85 and 0.9 ≦ X/Y ≦ 1.1.This is because following reason.If X is less than 85%, the weight rate that then constitutes the palladium of internal electrode 2 must increase, so just can not make the stack-up type piezo-activator with low cost.Again, if X/Y is less than 0.9, then the amount of the silver in the internal electrode 2 is with respect to the amount of the silver in the outer electrode 4 and relatively tail off, so when sintering outer electrode 4, the counterdiffusion mutually that is contained in the silver in internal electrode 2 and the outer electrode 4 respectively tails off, internal electrode 2 dies down with the bond strength of outer electrode 4, thereby the durability of stack-up type piezo-activator reduces.Again, if X/Y surpasses 1.1, then the amount of the silver in the outer electrode 4 relatively tails off with respect to internal electrode 2, so when sintering outer electrode 4, the counterdiffusion mutually that is contained in the silver in internal electrode 2 and the outer electrode 4 respectively tails off, internal electrode 2 dies down with the bond strength of outer electrode 4, thereby the durability of stack-up type piezo-activator reduces.
With respect to this, silver-colored weight rate in the electric conducting material of establishing internal electrode 2 is X (%), by being that silver-colored weight rate in the electric conducting material of principal component and the outer electrode 4 that glass constitutes is when being Y (%) with silver, if set X ≧ 85 and 0.9 ≦ X/Y ≦ 1.1, then can suppress to constitute the use amount of palladium of the high price of internal electrode 2, so can make multi-layer piezoelectric element with low cost.Again, because the silver-colored weight rate in the internal electrode 2 be X (%) with outer electrode 4 in silver-colored weight rate Y (%) about equally, so when sintering outer electrode 4, promoted to be contained in respectively the counterdiffusion mutually of the silver in internal electrode 2 and the outer electrode 4, internal electrode 2 becomes possibility with the strong bonded of outer electrode 4, even under the situation that long-time continuous under high electric field, the high pressure drives, internal electrode 2 and outer electrode 4 also and do not break, thereby can have good durability.
And then internal electrode 2 is made of electric conducting material and piezoelectric, when the silver-colored weight rate in making internal electrode 2 is Z (%), is preferably and satisfies 0.7 ≦ Z/Y ≦ 1.0.This is because following reason.If Z/Y is less than 0.7, the amount of the silver in the internal electrode 2 relatively tails off with respect to the amount of the silver in the outer electrode 4, thus the resistance value of internal electrode 2 than outer electrode 4 height, thereby in internal electrode 2, produce local pyrexia.Again, if Z/Y surpasses 1.0, then the piezoelectric in the internal electrode 2 tails off, thus internal electrode 2 and piezoelectrics 1 adhering to of interface connect airtight weakened, peel off thereby produce at the interface of internal electrode 2 and piezoelectrics 1.Again, the amount of the silver in the outer electrode 4 relatively tails off with respect to internal electrode 2, thus the counterdiffusion mutually of the silver between internal electrode 2 and the outer electrode 4 tail off, thereby the situation that has the bond strength of internal electrode 2 and outer electrode 4 to die down.
In present embodiment two, as in execution mode one, using Fig. 2 B, Fig. 2 C illustrating, be preferably: the end diffusion bond of outer electrode 4 and the internal electrode 2 that exposes in laminate 10 sides, the electric conducting material composition of internal electrode 2 is diffused in the outer electrode 4, forms neck 4b.If there is not neck 4b, then when the big electric current high-speed driving stack-up type piezo-activator that flows, externally the contact portions of electrode 4 and internal electrode 2 causes local pyrexia sometimes, perhaps produces spark etc.
Again, being preferably outer electrode 4 is made of the porous matter electric conductor that constitutes the three-dimensional network structure.If outer electrode 4 does not constitute with the porous matter electric conductor that constitutes the three-dimensional network structure, then outer electrode 4 does not have flexibility, so can not follow the flexible of stack-up type piezo-activator, so it is bad with the contact of internal electrode 2 to produce the broken string or the outer electrode 4 of outer electrode 4 sometimes.
And then illustrated as enforcement mode one, in present embodiment two, the voidage that also is preferably in the outer electrode 4 is 30～70% volumes.
And then being preferably externally, the piezoelectrics 1 side skin section of electrode 4 is formed with the glass enriched layer.This be because: if there is not a glass enriched layer, then with outer electrode 4 in glass ingredient engage the difficulty that becomes, be not easy this possibility so there is the firm engagement of outer electrode 4 and piezoelectrics 1 to become.
Again, be preferably the glass that constitutes outer electrode 4 softening point (℃) be the fusing point that constitutes the electric conducting material of internal electrode 2 (℃) below 4/5.This be because: if constitute the softening point of the glass of outer electrode 4 surpass the electric conducting material that constitutes internal electrode 2 fusing point 4/5, the softening point and the fusing point of the electric conducting material that constitutes internal electrode 2 that then constitute the glass of outer electrode 4 become the temperature of same degree, so inevitable fusing point of the temperature of sintering outer electrode 4 near the electric conducting material that constitutes internal electrode 2, thereby externally when the sintering of electrode 4, the electric conducting material aggegation of internal electrode 2 and outer electrode 4, hindered diffusion bond, perhaps sintering temperature can not be set at the softening temperature of glass ingredient that is enough to make outer electrode 4, so can not obtain the sufficient joint strength that produces based on softening glass sometimes.
And then being preferably the glass that constitutes outer electrode 4 is noncrystalline.This be because: if the glass of crystalloid, then outer electrode 4 can not absorb the flexible stress that produces because of the stack-up type piezo-activator, so crack sometimes etc.
Again and then, be preferably the thin thickness of the thickness of outer electrode 4 than piezoelectrics 1.This be because: if the thickness of outer electrode 4 is thicker than the thickness of piezoelectrics 1, then the intensity of outer electrode 4 increases, so when laminate 10 was flexible, outer electrode 4 increased with the load at the junction surface of internal electrode 2, it is bad to produce contact sometimes.
Again, as Fig. 2 and shown in Figure 3, be preferably and be filled with the Young's modulus insulator 3 lower than piezoelectrics 1 in the groove on the side that is formed at laminate 10, internal electrode 2 insulate every one deck ground with outer electrode 4.The piezoelectrics 1 that are sandwiched between the internal electrode 2 utilize the voltage between the internal electrode 2 that puts on the next-door neighbour to stretch, but with regard near the piezoelectrics 1 the side of the laminate 10 that is not sandwiched in internal electrode 2, even internal electrode 2 is applied voltage, and it is not flexible yet, so internal electrode 2 is applied voltage, all can produce compression stress or tensile stress at every turn.With respect to this, side at laminate 10 forms groove, in this groove, fill the Young's modulus insulator 3 lower, just can utilize insulator 3 to stretch to be reduced under the flexible situation of laminate 10 at the stress of the side of laminate 10 generation, just can improve durability with this with this than piezoelectrics 1.
At this moment, if it is bigger than piezoelectrics 1 to be filled in the Young's modulus of the insulator 3 in the described groove, then because can not relax near the stress that the side of laminate 10, produces with stretching of insulator 3 as described above, so there is the durability of multi-layer piezoelectric element to reduce this possibility.
Again, consider, be preferably the silver-palladium alloy that uses low palladium ratio as internal electrode 2 from the aspect of cost.Therefore, being preferably use can be at the piezoelectrics 1 of left and right sides sintering below 980 ℃, and the material that constitutes these piezoelectrics 1 is preferably with PbZrO
3-PbTiO
3Pb (the Yb that contains 10～20%mol for principal component, as accessory ingredient
1/2Nb
1/2) O
3, Pb (Co
1/3Nb
2/3) O
3And Pb (Zn
1/3Nb
2/3) O
3Material.That is, consider, when using palladium to be the silver-palladium alloy of 5% weight, as can using for example with PbZrO at the piezoelectrics 1 of 980 ℃ of following temperature sintering from the state diagram of silver-palladium alloy
3-PbTiO
3Pb (the Yb that contains 10～20%mol for principal component, as accessory ingredient
1/2Nb
1/2) O
3, Pb (Co
1/3Nb
2/3) O
3And Pb (Zn
1/3Nb
2/3) O
3Material.
At this, under the situation that the silver-palladium alloy with 5% weight palladium uses as internal electrode 2, if sintering temperature at 1100 ℃, then sintering temperature surpasses the fusing point of the electric conducting material (silver-palladium alloy) that constitutes internal electrode 2, the electric conducting material aggegation of internal electrode 2, thus this problem of delamination appears producing.That is,, the sintering temperature of piezoelectrics 1 must be reduced to 980 ℃ of following degree in order in the electric conducting material of internal electrode 2, to use the silver-palladium alloy of low palladium ratio.
Again, outer electrode 4 is in order fully to absorb the flexible stress that produces because of the stack-up type piezo-activator, it is that the alloy of principal component constitutes that the electric conducting material of outer electrode 4 is preferably by the low silver of Young's modulus or with silver, again, as outer electrode 4 integral body, be preferably with porous matter electric conductor formation flexibility, that constitute the three-dimensional network structure.
The stack-up type piezoelectric actuator of embodiment of the present invention two can similarly be made with the stack-up type piezo-activator of execution mode one.
At first, similarly make laminate 10 with execution mode one.
At this, consider that from the aspect of cost as the silver-palladium alloy that forms internal electrode 2 silver-palladium alloy of low palladium ratio preferably, particularly, being preferably the palladium ratio is the following silver-palladium alloy of 10% weight.For this reason, be preferably can be at the material of sintering below 980 ℃, as long as for example will be with PbZrO for piezoelectrics 1
3-PbTiO
3Pb (the Yb that contains 10～20%mol for principal component, as accessory ingredient
1/2Nb
1/2) O
3, Pb (Co
1/3Nb
2/3) O
3And Pb (Zn
1/3Nb
2/3) O
3Material be used in the piezoelectrics 1 and get final product.Again, the silver-palladium alloy that constitutes internal electrode can use the alloy powder of silver and palladium, also can use the mixture of silver powder and palladium powder.In addition, under the situation of the mixture that uses silver powder and palladium powder, when sintering, also form the alloy of silver-palladium.
Again, with regard to the ratio of the piezoelectric in making an addition to the conductive paste that is used to form internal electrode 2 (powders calcined of piezoelectric ceramic), owing to make internal electrode 2 firm with the bond strength of piezoelectrics 1, reduce the resistance value of internal electrode 2 again fully, so be preferably in the internal electrode 2 behind sintering and include electric conducting material 75～93% weight, piezoelectrics material 7～25% weight of remainder.
In addition, laminate 10 is not limited to utilize said method to make, as long as can make the laminate 10 that the alternately a plurality of piezoelectrics of lamination and a plurality of internal electrode form, then utilizes arbitrarily manufacture method to form and all can.
Produce after the laminate 10, as shown in Figure 3A, utilize cutter sweep etc. in the side of laminate 10 every the grooving of one deck landform.
And then, be in 450～800 ℃ glass powder 0.5～13% weight mixture that constitute to add adhesive make silver-colored glass conductive paste by silver powder 87～99.5% weight of particle diameter 0.1～10 μ m, with remainder particle diameter 0.1～10 μ m, that be principal component, softening point with silicon, it be shaped and dry (solvent is dispersed) and the green density of the plate 21 that obtains is controlled to be 6～9g/cm
3, shown in Fig. 3 B, the outer electrode that this plate 21 is needed on the laminate 10 that is formed with groove forms face, carries out sintering under temperature higher than the softening point of glass and the temperature below the silver point, can form outer electrode 4 with this.
Again, shown in Fig. 3 C, also can use the disappearance of dispersing of adhesive ingredients in the plate 21 that silver-colored glass conductive paste makes, the outer electrode 4 that formation is made of the porous matter electric conductor that constitutes the three-dimensional network structure, particularly, in order to form the outer electrode 4 of three-dimensional network structure, the green density of plate 21 is controlled to be 6～9g/cm
3, and then for the voidage that makes outer electrode 4 is 30～70%, being preferably and making green density is 6.2～7.0g/cm
3The green density of plate 21 can utilize Archimedes's method to measure.
Utilize the sintering of this silver glass paste to come externally to form space 4a in the electrode 4, and the silver in the silver-colored glass paste and the silver-palladium alloy diffusion bond in the internal electrode 2, formation neck 4b also can, outer electrode 4 partly is engaged in the side of laminate 10.In neck 4b, because the silver-colored counterdiffusion mutually of the silver-palladium alloy of internal electrode 2 and outer electrode 4, so the palladium of electrode diffusion can detect with common analytical method (for example, EPMA, EDS etc.) internally.
In addition, in order to form neck 4b effectively, the sintering temperature of described silver-colored glass paste is preferably set at scope illustrated in the execution mode one.
Again, the thickness of the plate 21 of silver-colored glass paste is preferably the thin thickness than piezoelectrics 1.In order to follow the flexible of stack-up type piezo-activator, more preferably below the 50 μ m.
Making the silver powder in the silver-colored glass conductive paste 21 is 87～99.5% weight, the glass powder of remainder be 0.5～13% weight be because: under the situation that silver powder is lacked than 87% weight, it is many that glass ingredient relatively becomes, when carrying out sintering, just externally form space 4a effectively or can not partly engage this outer electrode 4 and laminate 10 sides in the electrode 4, on the other hand, under the situation that silver powder is Duoed than 97% volume, 99.5% weight, glass ingredient relatively tails off, outer electrode 4 dies down with the bond strength of laminate 10, thereby the possibility that outer electrode 4 is peeled off from laminate 10 in the driving of stack-up type piezo-activator is arranged.
Again, the glass ingredient that constitutes outer electrode 4 uses silex glass, soda-lime glass, plumbous alkali silicate glasses, aluminium oxide borosilicate glass, borosilicate glass, alumina silicate glass, borate glass, phosphate glass, lead glass etc.
For example, as borosilicate glass, can use and contain SiO
240～70% weight, B
2O
32～30% weight, Al
2O
3Such alkaline earth metal oxide aggregate 0～10% weight of 0～20% weight, MgO, CaO, SrO, BaO, the glass of alkali metal oxide 0～10% weight.Again, above-mentioned borosilicate glass also can adopt the such glass of ZnO that includes 5～30% weight.ZnO has the effect of the processing temperature that reduces borosilicate glass.
As phosphate glass, can use to include P again,
2O
540～80% weight, Al
2O
30～30% weight, B
2O
30～30% weight, ZnO 0～30% weight, alkaline earth metal oxide 0～30% weight, the such glass of alkali metal oxide 0～10% weight.
As lead glass, can use to include PbO again,
30～80% weight, SiO
20～40% weight, Bi
2O
30～30% weight, Al
2O
30～20% weight, ZnO 0～30% weight, alkaline earth metal oxide 0～30% weight, the such glass of alkali metal oxide 0～10% weight.
Below, the stack-up type piezo-activator of execution mode two can similarly be made with execution mode one.
That is, the laminate 10 that will be formed with outer electrode 4 impregnated in silicone rubber solution, and carries out vacuum degassing, comes at the inner filled silicon rubber of the groove of laminate 10, and silicon rubber is solidified.
Then, lead 6 is connected on the outer electrode 4, utilizes lead 6 on pair of external electrodes 4, to apply the direct voltage of 0.1～3kV/mm, to laminate 10 processing that polarizes.With this, for example just finish as the stack-up type piezo-activator of the automotive fuel injection valve of engine spray fueling being brought into play its function.
Execution mode three
The multi-layer piezoelectric element of embodiment of the present invention three (stack-up type piezo-activator) is characterised in that, in the element shown in Figure 1A, Figure 1B etc., internal electrode 2 is by being principal component with silver and including palladium or at least a electric conducting material of platinum constitutes, again, outer electrode 4 is made of the electric conducting material and the glass ingredient that with silver are principal component, and is bigger than the silver-colored ratio of the electric conducting material in the internal electrode 2 of laminate 10 inside with near the silver-colored ratio of the electric conducting material of internal electrode 2 connecting portion of outer electrode 4.
The silver-colored ratio of the electric conducting material by making near the internal electrode 2 the connecting portion with outer electrode 4 like this is bigger than the silver-colored ratio of the electric conducting material in the internal electrode 2 of laminate 10 inside, the principal component that just can make outer electrode 4 electric conducting materials is that the concentration of the silver in silver and internal electrode 2 electric conducting materials is close, so by the phase counterdiffusion of silver, outer electrode 4 just becomes reliable with engaging of internal electrode 2.
Promptly, because the concentration of the silver near the electric conducting material of the internal electrode 2 the connecting portion of formation and outer electrode 4 and the concentration of the silver in the outer electrode 4 are about equally, so when being sintered in described outer electrode 4 on the described laminate 10, promoted the counterdiffusion mutually of the silver in silver and the described internal electrode 2 in the described outer electrode 4, thereby described internal electrode 2 becomes possibility with firm the engaging of described outer electrode 4, even at high electric field, under the situation that long-time continuous drives under the high pressure, described outer electrode 4 and described internal electrode 2 also and do not break, thereby can have good durability.
And then the silver-colored ratio in preferred internal electrode 2 electric conducting materials is along with become big gradually near outer electrode 4.Like this in internal electrode 2 electric conducting materials, just formed silver-colored concentration gradient continuously, so can establish engaging of stable internal electrode 2 and internal electrode 2 and outer electrode 4.
And then preferred outer electrode 4 utilizes neck 4b to come diffusion bond with internal electrode 2.With this, even under the situation of big electric current high-speed driving actuator that flows, because be formed with the neck 4b that can bear big electric current, so can prevent spark or broken string in this contact portion in the bonding part of internal electrode 2 and outer electrode 4.Again, because internal electrode 2 utilizes this neck 4b to come diffusion bond with outer electrode 4, thus do not have clear and definite composition boundary on the junction surface of internal electrode 2 and outer electrode 4, thus the high junction surface of reliability can be formed.In addition, the electric conducting material of the described neck 4b electric conducting material that is meant internal electrode 2 and outer electrode 4 counterdiffusion and the part that forms mutually.
And then, be more than 85% weight by making the silver-colored ratio in internal electrode 2 electric conducting materials, just can increase the concentration of the silver in the internal electrode 2, thereby can make reliable that diffusion bond because of silver forms with being connected of outer electrode 4.Again, be more than 85% weight by the silver-colored ratio in the electric conducting material that makes internal electrode 2, just can suppress the use amount of palladium at high price or platinum etc., so can make cheap multi-layer piezoelectric element.On the other hand, under the situation of silver-colored ratio in the electric conducting material of internal electrode 2 less than 85% weight, the palladium of high price or the use amount of platinum must increase, so can not make cheap multi-layer piezoelectric element, again, because the concentration step-down of the silver in the electric conducting material of internal electrode 2, so become unreliable with engaging of outer electrode 4.In addition, the silver-colored ratio in internal electrode 2 electric conducting materials is meant in laminate 10 inside of the silver-colored constant rateization in internal electrode 2 electric conducting materials and leaves the silver-colored ratio of the junction surface 1mm of outer electrode 4 with top.
And then the preferred externally piezoelectrics 1 side skin section of electrode 4 is provided with the glass enriched layer.By glass ingredient in the outer electrode 4 is present on the joint interface with piezoelectrics 1 morely, just can improve the bond strength of outer electrode 4 and laminate 10 sides.
And then, be preferably below 80% of laminate 10 top layer sides that glass ingredient in the outer electrode 4 is present in outer electrode 4 thickness substantially.With this, because undertaking the skin section that the glass ingredient that engages this effect with laminate 10 is present in piezoelectrics 1 side, so outer electrode 4 becomes possibility with strong the engaging of laminate 10, on the other hand, externally in fact only to exist with silver be the electric conducting material of principal component to the atmospheric side skin section of electrode 4, even thereby when being connected and fixed on lead etc. on the described outer electrode 4, also can provide the good outer electrode of scolding tin wetting quality 4 surfaces with scolding tin.
And then, be preferably in the glass ingredient in the electrode 4 externally and include lead oxide or bismuth oxide.That is,, just can make outer electrode 4 firm with engaging of piezoelectrics by including lead oxide or the bismuth oxide high in the glass ingredient in the electrode 4 externally with the bond strength of piezoelectrics 1.On the other hand, externally do not include under the situation of lead oxide or bismuth oxide in the glass ingredient in the electrode 4, outer electrode 4 is peeled off the possibility of this problem when having generation to drive from laminate 10 sides.
Again, consider, be preferably the silver-palladium alloy that uses low palladium ratio as internal electrode 2 from the aspect of cost.Therefore, preferably using can be at the piezoelectrics 1 of sintering below 980 ℃, and the material that constitutes these piezoelectrics 1 is preferably with PbZrO
3-PbTiO
3Pb (the Yb that contains 10～20%mol for principal component, as accessory ingredient
1/2Nb
1/2) O
3, Pb (Co
1/3Nb
2/3) O
3And Pb (Zn
1/3Nb
2/3) O
3Material.That is, consider, when the silver-palladium alloy that uses palladium 5% weight, as can using at the piezoelectrics 1 of the sintering temperature below 980 ℃ with PbZrO from the state diagram of silver-palladium alloy
3-PbTiO
3Pb (the Yb that contains 10～20%mol for principal component, as accessory ingredient
1/2Nb
1/2) O
3, Pb (Co
1/3Nb
2/3) O
3And Pb (Zn
1/3Nb
2/3) O
3Material.
At this, under the situation that the silver-palladium alloy with palladium 5% weight uses as internal electrode 2, if sintering temperature at 1100 ℃, then sintering temperature surpasses the fusing point of the electric conducting material (silver-palladium alloy) that constitutes internal electrode 2, the electric conducting material aggegation of internal electrode 2, thus this problem of delamination appears producing.That is,, the sintering temperature of piezoelectrics 1 must be reduced to 980 ℃ of following degree in order in the electric conducting material of internal electrode 2, to use the silver-palladium alloy of low palladium ratio.
The manufacture method of the stack-up type piezo-activator that is made of multi-layer piezoelectric element of the present invention then, is described.
In this manufacture method, similarly make laminate 10 with execution mode two, as shown in Figure 3A, utilize cutter sweep to form groove in the side of laminate 10 every one deck ground.
Then, following formation outer electrode 4.
At first, by silver powder 87～99.5% weight of particle diameter 0.1～10 μ m, with remainder particle diameter 0.1～10 μ m and include lead oxide or mixture that at least a above glass powder 0.5～13% weight of bismuth oxide constitutes in the adding adhesive make lower floor with silver-colored glass paste.And then, in the silver powder of particle diameter 0.1～10 μ m, add adhesive and make the silver-colored paste in upper strata.
And, on the film that the demoulding is handled, come screen printing lower floor with silver-colored glass paste 21a with the thickness of 5～40 μ m, after the drying, come the screen printing upper strata with silver-colored paste 21b with the thickness of 5～40 μ m thereon.And then after the drying, peel off paste plate 21 from mould release film, shown in Fig. 3 (b), the mode that becomes laminate 10 sides with lower floor with silver-colored glass paste is needed on this paste plate 21 on the outer electrode 4 formation faces of the laminate 10 that is formed with groove, carrying out sintering than being contained under lower floor's temperature high and the temperature below the silver point with the softening point of the glass ingredient in the silver-colored glass paste, shown in Fig. 3 (c), just can form outer electrode 4 with this, described outer electrode 4 is formed with neck 4b.
In addition, in order to make silver-colored ratio in internal electrode 2 electric conducting materials effectively along with become big gradually near outer electrode 4, be preferably at exponential function Y and represent under the situation of sintering pattern of outer electrode 4 with the temperature shown in the formula 1, come integration Y and the value that obtains is more than 1000 with the time (unit minute), more preferably 1800～4000.
(formula 1) Y=exp ((T+273)/273) [unit of T be ℃]
By making the value of coming integration Y to obtain with the time (branch) like this is 1800～4000, just can make silver-colored ratio in internal electrode 2 electric conducting materials along with become big gradually near outer electrode 4 effectively, again, externally electrode 4 forms neck 4b with the junction surface of internal electrode 2, and then externally the laminate 10 top layer sides of electrode 4 form the glass enriched layer.
Mode by becoming laminate 10 sides with silver-colored glass paste with lower floor is to carrying out sintering with silver-colored glass paste and the upper strata that does not include glass ingredient with the paste plate 21 that silver-colored paste constitutes by the lower floor that includes glass ingredient like this, and just externally the laminate 10 top layer sides of electrode 4 are provided with the glass enriched layer.By the lower floor that forms described paste plate 21 is controlled with the thickness of silver-colored paste with silver-colored glass paste and upper strata, just can make glass ingredient in the outer electrode 4 be present in below 80% of laminate 10 top layer sides of outer electrode 4 thickness substantially again.And then, utilize described sintering to form neck 4b, in neck 4b, the silver-colored counterdiffusion mutually of the silver-palladium alloy of internal electrode 2 and outer electrode 4 is so can detect the palladium that electrode 2 internally spreads with common analytical method (for example, EPMA, EDS).
In addition, the formation method of outer electrode 4 is not limited to said method, directly is printed on the outer electrode 4 formation faces of laminate 10 sides also can.And then, in said method, form outer electrode 4 with 1 sintering, but transfer printing or the printing lower floor with silver-colored glass paste after, carry out sintering, then, transfer printing or the printing upper strata with silver-colored paste after, carry out sintering again, promptly form outer electrode 4 and also can with 2 sintering.
Again, the thickness of outer electrode 4 is preferably the thin thickness than piezoelectrics 1.In order to follow actuator body is the flexible of laminate, more preferably below the 50 μ m.
Making lower floor is 80～99.5% weight with the silver powder in the silver-colored glass paste, the glass powder of remainder be 0.5～13% weight be because: under the situation that silver powder is lacked than 80% weight, it is big that the ratio resistance of outer electrode 4 becomes, thereby under the situation of big electric current high-speed driving that flows, might in this outer electrode 4, cause local pyrexia, on the other hand, under the situation that silver powder is Duoed than 99.5% weight, glass ingredient relatively tails off, outer electrode 4 dies down with the bond strength of laminate 10, peels off this problem thereby might be created in the driving outer electrode 4 from laminate 10.
Do not include glass ingredient on the upper strata in silver-colored paste again.This be because: utilizing scolding tin lead 6 to be connected and fixed under the situation on the outer electrode 4, if glass ingredient is present in the atmospheric side top layer part of outer electrode 4, then the wetting quality of scolding tin reduces significantly, lead 6 reduces to the bond strength of outer electrode 4, thereby this lead 6 might come off in driving.
By in the glass ingredient of lower floor, including at least a of lead oxide or bismuth oxide, just can improve bond strength with laminate 10 with silver-colored glass paste again.
Below, the stack-up type piezo-activator of execution mode two can similarly be made with execution mode first-class.
That is, the laminate 10 that will be formed with outer electrode 4 impregnated in the silicone rubber solution, and it is carried out vacuum degassing, just is filled into the groove inside of laminate 10 with this silicon rubber, and silicon rubber is solidified.
Then, lead 6 is connected to outer electrode 4, utilizes lead 6 to come pair of external electrodes 4 is applied the direct current of 0.1～3kV/mm, to laminate 10 processing that polarizes.With this, for example just finished as the stack-up type piezo-activator of the automotive fuel injection valve of engine spray fueling being brought into play its function.
In the execution mode one to three of above explanation, piezoelectrics 1 are for example by with lead zirconate titanate Pb (Zr, Ti) O
3(the following PZT that slightly is called) or barium titanate BaTiO
3Formation such as piezoceramic material for principal component.This piezoelectric ceramic is preferably the piezoelectricity distortion constant d33 height of its piezoelectric property of expression.
Again, in execution mode one to three, the thickness of piezoelectrics 1 is that the distance of 2 of internal electrodes is preferably 0～250 μ m.With this,, also can realize miniaturization, the low level of actuator, and can prevent the insulation breakdown of piezoelectrics 1 even the stack-up type piezo-activator increases the lamination number in order to apply voltage so that obtain bigger addendum modification.
And then in present embodiment one to three, as shown in Figure 4, externally the outer surface of electrode 4 is formed with the conductivity accessory 7 that the conductive adhesive 7a by net that is embedded with metal or cancellous metallic plate 7b constitutes and also can.Under this situation, by the outer surface of electrode 4 externally conductivity accessory 7 is set, even then, also can make big electric current flow into conductivity accessory 7, thereby reduce the electric current that flow in the outer electrode 4 big electric current being put under actuator, the situation with high-speed driving.With this, can prevent that outer electrode 4 from causing local pyrexia and break, thereby can improve durability significantly.And then, if in conductive adhesive 7a, bury the net or the cancellous metallic plate 7b of metal underground, then can prevent from conductive adhesive 7a, to crack.
Again, externally the outer surface of electrode 4 does not use under the situation of net or cancellous metallic plate, just might directly act on the outer electrode 4 because of the flexible stress that produces of laminate 10, outer electrode 4 is peeled off from the side of laminate 10 easily because of the fatigue in driving easily.
The net of metal is meant the braided metal line and the net that obtains, and cancellous metallic plate is meant and forms the hole on metallic plate, make cancellous metallic plate.
At this, preferred conductive adhesive is made of the polyimide resin that is dispersed with electroconductive particle.This be because: by using polyimide resin, even when at high temperature driving laminate 10, have than higher stable on heating polyimide resin owing to use, conductive adhesive is also kept high-adhesive-strength easily.
Again, the conductive adhesive 7a that more preferably constitutes described conductivity accessory 7 is made of the polyimide resin that is dispersed with the silver powder lower than resistance.This be because: by in electroconductive particle, using the lower silver powder of resistance value, just suppress the local pyrexia in the conductive adhesive easily.
And then to be preferably described electroconductive particle be laminar or the aspheric particle of needle-like etc.This be because: by making the aspheric particle of the laminar or needle-like of being shaped as of electroconductive particle etc., just can make the polymerization between this electroconductive particle firm, thereby can further improve the shear strength of this conductive adhesive 7a.
Execution mode four
Fig. 5 represents the injection apparatus of embodiment of the present invention four, uses piezo-activator of the present invention and constitutes.Symbol 31 expression accommodating containers in Fig. 5.End at this accommodating container 31 is provided with spray-hole 33, contains the needle valve 35 that can open and close spray-hole 33 again in accommodating container 31.
The fuel passage 37 that can be communicated with spray-hole 33 is set, and this fuel passage 37 is linked to outside fuels sources, and fuel is supplying in the fuel passage 37 under the constant high pressure always.Thereby be formed as follows: if needle valve 35 open spray-holes 33, the fuel that then supplies in the fuel passage 37 is ejected under constant high pressure in the not shown fuel chambers of internal combustion engine.
Again, it is big that the upper end diameter of needle valve 35 becomes, and becomes the piston 41 that can slide with the cylinder 39 that is formed in the accommodating container 31.And, in accommodating container 31, taken in above-mentioned piezo-activator 43.
At this, piezo-activator 43 is piezo-activators of the present invention.
In such injection apparatus, if piezo-activator is applied in voltage and extends, then piston 41 is pressed, needle valve 35 inaccessible spray-holes 33, thus the supply of fuel stops.Again, if voltage application stops, then piezo-activator 43 shrinks, and disk spring 45 pushes back piston 41, and spray-hole 33 is communicated with fuel passage 37, thereby carries out the injection of fuel.
In such device, illustrated as enforcement mode one to three, can in multi-layer piezoelectric element, suppress the broken string of outer electrode and internal electrode, can improve durability significantly, so the durability of injection apparatus also can improve.
Embodiment one
As embodiment one, at first make laminate.Piezoelectrics form with the PZT of thickness 150 μ m, and internal electrode forms with the silver-palladium alloy (containing Pd10% weight) of thickness 3 μ m, and piezoelectrics and internal electrode lamination number separately is 300 layers.In addition, sintering temperature is 1000 ℃.
As shown in Figure 3A, utilize cutter sweep on the end of the internal electrode of the side of laminate every one deck ground form the groove of the degree of depth 50 μ ms, width 50 μ ms thereafter.
Then, laminar silver powder 90% volume of average grain diameter 2 μ m, with remainder average grain diameter 2 μ m, that with silicon be principal component, softening point be in 640 ℃ the mixture of amorphous glass powder 10% volume, total weight 100 mass parts with respect to silver powder and glass powder are added the adhesive of 8 mass parts, mix fully and make silver-colored glass conductive paste.The silver-colored glass conductive paste that utilizes screen printing to make like this and obtain is formed on the mould release film, and peel off from mould release film dry back, thereby obtains the plate of silver-colored glass conductive paste.The green density of utilizing Archimedes's method to measure this plate is 6.5g/cm
3
Then, shown in Fig. 3 B, the plate of described silver-colored glass paste is needed on the external electric pole-face of laminate,, shown in Fig. 3 C, forms the outer electrode that constitutes by the porous matter electric conductor that constitutes the three-dimensional network structure 650 ℃ of following sintering 30 minutes.In addition, by using section photo that image analysis apparatus measures outer electrode as can be known, the voidage of the outer electrode of this moment is 40%.Again, utilize analytical electron microscope (EPMA) to measure as can be known, silver-palladium alloy counterdiffusion mutually, joint in the silver in the silver-colored glass conductive paste and the internal electrode, with the junction surface of internal electrode on be formed with palladium electrode diffusion and the neck that obtains internally.And then, utilize the section photo of outer electrode to measure as can be known, the bonding part of outer electrode and laminate side is about 50%.
, connect the line to outer electrode, utilize lead that anodal outer electrode with negative pole is applied the DC electric field of 15 minutes 3kV/mm thereafter, the processing that polarizes, thus produce as shown in Figure 1 stack-up type piezo-activator.
The direct voltage of 170V is put on the stack-up type piezo-activator that obtains, consequently, on the lamination direction, obtain the addendum modification of 45 μ m.And then, at room temperature with the frequency of 150Hz to this actuator apply 0～+ alternating voltage of 170V consequently, drives and circulated 2 * 10 to drive test
8After inferior, obtain the addendum modification of 45 μ m, do not found the unusual of outer electrode.Again, except the green density that makes silver-colored glass conductive paste changes, the voidage that forms outer electrode is beyond the outer electrode of 30% volume, 70% volume, with the above-mentioned stack-up type piezo-activator of similarly making, and it is estimated as can be known, drive and circulated 2 * 10
8After inferior, obtain the addendum modification of 45 μ m, do not found the unusual of outer electrode.
Comparative example 1
Except side and dry (the green density 9.1g/cm that silver-colored glass conductive paste is coated on laminate
3), sintering temperature is changed to beyond 820 ℃ the stack-up type piezo-activator of the formation that making and embodiment are same.The outer electrode of this moment does not constitute three-dimensional network structure, but is block roughly, and voidage is 10%, has the space of sphere, whole engages with the laminate side.
With embodiment similarly, at room temperature with the frequency of 150Hz to the stack-up type piezo-activator that obtains apply 0～+ alternating voltage of 170V consequently, drives and circulated 5 * 10 to drive test
6After inferior, the outer electrode broken string produces spark.
Embodiment two
Make multi-layer piezoelectric element of the present invention as follows as embodiment two.
At first, make the slurry that is mixed with PZT the powders calcined, adhesive and the plasticizer that are the piezoelectric ceramic of principal component, make the ceramic green sheet of the piezoelectrics 1 of formation thickness 150 μ m with the scraper legal system.
Utilize the screen printing will be by being that the mode of 85～95% weight is mixed with and adds the conductive paste that adhesive obtains in the silver-palladium alloy of palladium and be formed on the single face of this ceramic green sheet at weight rate X (%) with silver with the thickness of 3 μ m, 300 described ceramic green sheets of lamination, and under 980～1100 ℃, carry out sintering, thereby obtain the laminate 10 of Fig. 1.
Then, as shown in Figure 3A, utilize cutter sweep on the end of the internal electrode 2 of laminate 10 sides, to form the groove of the degree of depth 50 μ m, width 50 μ m every one deck ground.
Then, to be that the mode of 84～97% weight is mixed the laminar silver powder of average grain diameter 2 μ m and average grain diameter 2 μ m, that with silicon be principal component, softening point is amorphous glass powder of 640 ℃ with the weight rate Y (%) of silver, and then, add and mix the adhesive of 8 weight portions with total weight 100 weight portions of glass powder with respect to silver powder, thereby make silver-colored glass conductive paste.The silver-colored glass paste that utilizes screen printing to make like this is formed on the mould release film, after the drying, peel off from mould release film, thereby obtain the plate of silver-colored glass conductive paste, plate with described silver-colored glass conductive paste is needed on the opposed a pair of side of laminate 10 afterwards, under 650 ℃, carry out 30 minutes sintering, thereby form outer electrode 4.
Again, on the junction surface of internal electrode 2 and outer electrode 4, be formed with the neck 4b that obtains by the silver-colored counterdiffusion mutually in the silver-colored glass conductive paste in the silver-palladium alloy in the internal electrode 2 and the outer electrode 4, utilize EPMA to come this neck 4b is analyzed and can confirm, palladium electrode 2 diffusions internally.
Again, with regard to the voidage of the outer electrode 4 of above-mentioned formation, the section photo analysis that utilizes outer electrode 4 as can be known, voidage is 40%.And then, utilize the section photo of outer electrode 4 to measure as can be known, outer electrode 4 is about 50% with the bonding part of laminate 10 sides.Externally be formed with the glass enriched layer that the glass ingredient institute segregation in the silver-colored glass conductive paste forms on the piezoelectricity side skin section of electrode 4 again.
, lead be connected in outer electrode on, utilize lead that the outer electrode of positive pole and negative pole is applied the DC electric field of 15 minutes 3kV/mm thereafter, the processing that polarizes, thus make as shown in Figure 1 stack-up type piezo-activator.
In the stack-up type piezo-activator of the present invention that the method for stating is in the use made, in the scope of X ≧ 85, form the silver-colored weight rate Y (%) in silver-colored weight rate X (%) and the outer electrode in internal electrode 2 electric conducting materials, and related between the driving of the value of checking X/Y and stack-up type piezo-activator.
As a comparative example, make to make the value of X/Y at X/Y＜0.9, perhaps X/Y again,〉sample that forms in 1.1 the scope.
To the above-mentioned stack-up type piezo-activator that obtains like that, when applying the direct voltage of 185V, in all stack-up type piezo-activators, all on the lamination direction, obtain the addendum modification of 49 μ m.And then, at room temperature with the frequency of 150Hz to these stack-up type piezo-activators apply 0～+ AC field of 185V, circulate 2 * 10
8Inferior driving test.The result is as shown in table 1.
[table 1]
Evaluation result (2 * 10 in the outer electrode in the internal electrode
8
Sample number X/Y value
After Y the circulation of silver weight rate X silver weight rate)
1 95 97 0.98 is no abnormal
2 95 86.5 1.1 is no abnormal
3 88 97.5 0.9 is no abnormal
*4 85 97 0.88 addendum modifications reduce
*5 95 84 1.13 addendum modifications reduce
As known from Table 1, comparative example be sample number 4 because the value of its X/Y less than 0.9, so the amount of the silver in the internal electrode 2 relatively tails off with respect to outer electrode 4, again, the quantitative change of the silver in the internal electrode 2 is few, fusing point with this internal electrode 2 uprises, so the counterdiffusion mutually of silver tails off between internal electrode 2 and outer electrode 4, intensity with this neck 4b reduces, so drive in high-speed and continuous under the situation of stack-up type piezo-activator, neck 4b breaks because of the laminate 10 flexible stress that produced, thereby voltage can not supply in the piezoelectrics 1 of a part, so increase along with driving circulation, the addendum modification of laminate 10 reduces, so reduce as the durability of stack-up type piezo-activator.
Again, comparative example is that sample number 5 is because the value of its X/Y surpasses 1.1, so the amount of the silver in the outer electrode 4 is with respect to the amount of the silver in internal electrode 2 electric conducting materials and relatively tail off, the counterdiffusion mutually of silver tails off between internal electrode 2 and outer electrode 4, with this and similarly above-mentioned, neck 4b breaks because of the laminate 10 flexible stress that produced, thereby voltage can not supply in the piezoelectrics 1 of a part, so increase along with driving circulation, the addendum modification of laminate 10 reduces, so reduce as the durability of stack-up type piezo-activator.
With respect to this, at embodiments of the invention is in the sample number 1～3, it is the stack-up type piezo-activator that in the scope of X ≧ 85 and 0.9 ≦ X/Y ≦ 1.1, forms, so promoted the counterdiffusion mutually of silver between internal electrode 2 and outer electrode 4, thereby internal electrode 2 becomes firmly with engaging of outer electrode 4, so 2 * 10
8Also can obtain the addendum modification of 49 μ m after the inferior circulation, again, 2 * 10
8Externally do not produce the unusual of spark or broken string etc. in the electrode 4 after the inferior circulation, thereby have good durability as the stack-up type piezo-activator.
Embodiment three
In embodiment three, in the stack-up type piezo-activator of making at the internal electrode 2 that uses the conductive paste that forms with the powders calcined that in silver-palladium alloy, adds piezoelectric ceramic to form, the weight rate that makes the silver of the internal electrode 2 with electric conducting material and piezoelectric is Z (%), form the stack-up type piezo-activator with silver-colored weight rate Y (%) in the electrode 4 externally and silver-colored weight rate Z (%) in the internal electrode 2, and related between the driving of the value of checking Z/Y and stack-up type piezo-activator.Manufacture method is identical with embodiment two.
To the above-mentioned stack-up type piezo-activator that obtains like that, when applying the direct voltage of 185V, in all samples, all on the lamination direction, obtain the addendum modification of 49 μ m.And then, at room temperature with the frequency of 150Hz to these stack-up type piezo-activators apply 0～+ AC field of 185V, circulate 5 * 10
8Inferior driving test.The result is as shown in table 2.
[table 2]
Evaluation result (5 * 10 in the outer electrode in the internal electrode
8Inferior following
Sample number Z/Y value
After the silver weight rate Z silver weight rate Y ring)
6 80 97 0.82 is no abnormal
7 86.5 868 1 is no abnormal
8 68.5 97.5 0.7 is no abnormal
9 90 84 1.07 addendum modifications reduce
10 63 96 0.66 addendum modifications reduced than the initial stage
As known from Table 2, sample number 9 is because the value of its Z/Y is bigger than 1.0, so the piezoelectric in the internal electrode 2 tails off, thereby internal electrode 2 adhering to of interface connects airtight weakened with piezoelectrics 1, peel off so in driving, on the part of internal electrode 2 and piezoelectrics 1, produce, voltage can not supply on the piezoelectrics 1 of a part, thereby addendum modification reduces.
Again, sample number 10 is because the value of its Z/Y is littler than 0.7, so the quantitative change of the silver in the internal electrode 2 is few, thereby compare with outer electrode 4, the resistance value of internal electrode 2 uprises, so under the situation of high-frequency Continuous Drive, because of the voltage decline that this high resistance caused just can not supply to sufficient voltage in the piezoelectrics 1, thereby addendum modification reduces.
With respect to this, in sample number 6～8,5 * 10
8Also can access the addendum modification of 49 μ m after the inferior circulation, not produce broken string etc. unusual of internal electrode 2 and the contact portion of outer electrode 4.
Embodiment four
The stack-up type piezo-activator that following making is made of multi-layer piezoelectric element of the present invention.
At first, with embodiment two laminate 10 of construction drawing 1 similarly, as shown in Figure 3A, utilize cutter sweep on the end of the internal electrode 2 of laminate 10 sides, to form the groove of the degree of depth 50 μ m, width 50 μ m every one deck ground.
Then, mix average grain diameter 2 μ m silver powder 80～99.5% weight, with the glass powders at least a, average grain diameter 2 μ m that include lead oxide or bismuth oxide, and then, add adhesive, make lower floor with silver-colored glass paste.Similarly, in the silver powder of average grain diameter 2 μ m, add adhesive, make the upper strata with silver-colored glass paste.
Then, utilize screen printing lower floor to be printed onto on the mould release film with silver-colored glass paste, after the drying, utilize screen printing the upper strata to be printed onto on it with silver-colored glass paste with the thickness of 5～40 μ m with the thickness of 5～40 μ m.In drying after the described paste, peel off from mould release film, thereby obtain the paste plate.Thereafter, the mode that becomes laminate 10 top layer sides with lower floor with silver-colored glass paste is transferred to described paste plate on the opposed a pair of side of laminate 10 sides, carries out 30 minutes sintering under 800 ℃, thereby forms outer electrode 4.In addition, at this moment, the value of coming the Y of integration type 1 to obtain with the time (branch) is 3240.
Utilize quantitative analysis that EPMA comes internal electrode 2 is carried out element as can be known along the line X shown in Fig. 2 B, as shown in Figure 5, the silver-colored ratio in internal electrode 2 electric conducting materials is from increasing gradually towards the connecting portion that is connected on the outer electrode 4 near the connecting portion 50 μ m that are connected in outer electrode 4.
Again, on the junction surface of internal electrode 2 and outer electrode 4, be formed with the silver-colored counterdiffusion mutually in silver-palladium alloy and the outer electrode 4 in the internal electrode 2 and the neck 4b that obtains, utilize EPMA that this neck 4b is analyzed and can confirm, palladium electrode 2 internally spreads.
Again, externally the piezoelectricity side skin section of electrode 4 is formed with the glass ingredient segregation and the glass enriched layer that obtains.And then the glass ingredient that is contained in the outer electrode 4 is present in below 60% of laminate 10 top layer sides substantially.
, lead be connected in outer electrode thereafter, the processing that polarizes of the DC electric field of utilizing lead that the outer electrode of positive pole and negative pole is applied 15 minutes 3kV/mm, thus make as shown in Figure 1 stack-up type piezo-activator.
Embodiment five
In embodiment five, except the kind and sintering temperature thereof of the conductive paste that change to form outer electrode 4, use the manufacture method identical to make multiple stack-up type piezo-activator with embodiment four.To the stack-up type piezo-activator that obtains, near the silver-colored ratio internal electrode 2 electric conducting materials and connecting portion outer electrode 4, analyze with respect to the ratio of the silver-colored ratio of laminate 10 inside.To the above-mentioned stack-up type piezo-activator that obtains like that, apply the direct voltage of 185V, in all stack-up type piezo-activators, all on the lamination direction, obtained the displacement of 49 μ m.And then, at room temperature with the frequency of 150Hz to these stack-up type piezo-activators apply 0～+ AC field of 185V, circulate 2 * 10
8Inferior driving test.The result is as shown in table 3.
[table 3]
The ratio evaluation result of the silver-colored ratio silver ratio in the internal electrode electric conducting material
Sample number laminate internal-external electrode connects (E/I) 2 * 10
8After the inferior circulation
(I%) near the portion (E%)
11 95 98 1.03 is no abnormal
12 85 95 1.12 is no abnormal
*13 95 95 1.00 addendum modifications reduce
From this table 3 as can be known, comparative example is a sample number 13 because near its internal electrode 2 electric conducting materials and connecting portion outer electrode 4 silver-colored ratio, ratio with respect to the silver-colored ratio of laminate 10 inside is big unlike 1, promptly with the connecting portion of outer electrode 4 near internal electrode 2 electric conducting materials in silver-colored ratio big unlike the silver-colored ratio in internal electrode 2 electric conducting materials of laminate 10 inside, so a little less than the bond strength of the contact portions of internal electrode 2 and outer electrode 4, so the internal electrode 2 of a part is peeled off with the contact portions of outer electrode 4 in driving, voltage can not supply in the piezoelectrics 1 of a part, thereby displacement properties reduces.
With respect to this, embodiments of the invention be sample number 11 and 12 its with the connecting portion of outer electrode 4 near internal electrode 2 electric conducting materials in silver-colored ratio bigger than the silver-colored ratio in internal electrode 2 electric conducting materials of laminate 10 inside, so the bond strength height of internal electrode 2 and outer electrode 4 is 2 * 10
8Also can access the addendum modification of 49 μ m after the circulation, again, 2 * 10
8Externally do not produce the unusual of spark or broken string etc. on the electrode 4 after the circulation yet, thereby have good durability as the stack-up type piezo-activator.
Embodiment six
In embodiment six, change the kind and the sintering temperature thereof of the conductive paste that forms outer electrode 4, make multiple stack-up type piezo-activator.Sample number 16 does not externally have the glass enriched layer on laminate 10 skin section of electrode 4, sample number 17 externally the thickness of electrode 4 laminate top layer side 95% on have glass ingredient.To the stack-up type piezo-activator that obtains, the direct voltage that applies 185V as can be known, all samples can both obtain the addendum modification of 49 μ m on the lamination direction.And then, to these stack-up type piezo-activators, at room temperature with the frequency of 150Hz apply 0～+ AC field of 185V, circulate 5 * 10
8Inferior driving test.The result is as shown in table 4.
[table 4]
Evaluation result
The distribution 5 * 10 of sample number glass enriched layer glass ingredient
8After the inferior circulation
14 have below 60% no abnormal
15 have below 80% no abnormal
*16 do not have 60% following addendum modification reduces
*17 have 95% following wire dropping
As known from Table 4, sample number 16 is not because externally there is the glass enriched layer in laminate 10 skin section of electrode 4, so a little less than the bond strength of outer electrode 4 with respect to laminate 10, outer electrode 4 is peeled off from laminate 10 in the driving, voltage can not supply on the piezoelectrics 1 of a part, thereby displacement properties reduces.Again, sample number 17 externally electrode 4 thickness laminate 10 top layer sides 95% on have glass ingredient, so be connected and fixed a little less than the bond strength of scolding tin with respect to outer electrode 4 of lead 6, thereby lead 6 comes off in driving.
With respect to this, in sample number 14 and 15,5 * 10
8Also can access the addendum modification of 49 μ m after the inferior circulation, broken string etc. unusual of internal electrode 2 and the contact portion of outer electrode 4 do not take place.
Industrial applicibility
Multi-layer piezoelectric element of the present invention can be used in the piezoelectric transformer. Again, of the present invention long-pending The stratotype piezoelectric element can be used in the essence that is used in automotive fuel injection apparatus, Optical devices etc. Close positioner or vibration prevent in the stack-up type piezo-activator in driving element of usefulness etc. Advance And the multi-layer piezoelectric element of the application of the invention can be used in automotive fuel or spray In the injection apparatus of the printing ink of China ink printer etc.
Claims (18)
1. multi-layer piezoelectric element, it comprise piezoelectrics and internal electrode alternately the laminate that forms of lamination, be formed at first side of this laminate and the outer electrode on second side respectively, a side internal electrode is connected with described outer electrode in described first side in the internal electrode of adjacency, and the opposing party's internal electrode is connected with described outer electrode in described second side; It is characterized in that,
Described outer electrode is made of the porous matter electric conductor that contains electric conducting material and glass and constitute three-dimensional network structure, described outer electrode local engagement is formed with the space between described piezoelectrics and described outer electrode on described first side and described second side.
2. multi-layer piezoelectric element as claimed in claim 1 is characterized in that, the principal component of the electric conducting material of described outer electrode is a silver.
3. multi-layer piezoelectric element as claimed in claim 1 is characterized in that, the softening point that is contained in the glass in the described outer electrode is below the fusing point of the electric conducting material that constitutes described outer electrode.
4. multi-layer piezoelectric element as claimed in claim 1 is characterized in that the metal ingredient of described internal electrode is principal component with Ag, and contains following Pd of 15% weight and in the Pt family metal more than one.
5. multi-layer piezoelectric element, it comprise piezoelectric body layer and internal electrode alternately the laminate that forms of lamination, be formed at first side of this laminate and the outer electrode on second side respectively, a side internal electrode is connected with outer electrode in described first side in the internal electrode of adjacency, and the opposing party's internal electrode is connected with outer electrode in second side; It is characterized in that,
Described internal electrode and described outer electrode include silver respectively,
In establishing described internal electrode, be X% with respect to the silver-colored weight rate of electric conducting material integral body,
If in the described outer electrode, when being Y% with respect to the weight rate of the silver of the total weight of electric conducting material and glass,
To satisfy the mode of X ≧ 85 and 0.9 ≦ X/Y ≦ 1.1, set the silver-colored ratio of described internal electrode and described outer electrode.
6. multi-layer piezoelectric element as claimed in claim 5, it is characterized in that, described internal electrode includes piezoelectric, when the silver-colored weight rate with respect to the total weight that includes described piezoelectric in establishing described internal electrode is Z%, satisfies 0.7 ≦ Z/Y ≦ 1.0.
7. multi-layer piezoelectric element as claimed in claim 5 is characterized in that, described outer electrode is made of the porous matter electric conductor that constitutes the three-dimensional network structure.
8. multi-layer piezoelectric element as claimed in claim 5 is characterized in that, the softening point that is used for the glass of described outer electrode is below 4/5 of fusing point that constitutes the electric conducting material of described internal electrode.
9. multi-layer piezoelectric element as claimed in claim 1 is characterized in that, the voidage of described outer electrode is 30～70% volumes.
10. multi-layer piezoelectric element as claimed in claim 1 is characterized in that, the glass that constitutes described outer electrode is noncrystalline.
11. multi-layer piezoelectric element as claimed in claim 1 is characterized in that, said external electrode and internal electrode diffusion bond.
12. multi-layer piezoelectric element as claimed in claim 1 is characterized in that, skin section is provided with the glass enriched layer on the piezoelectricity side of said external electrode.
13. multi-layer piezoelectric element as claimed in claim 1 is characterized in that, the thickness of described outer electrode is than the thin thickness of the piezoelectrics that constitute described laminate.
14. multi-layer piezoelectric element as claimed in claim 1, it is characterized in that, in described first side, between the end of described the opposing party's internal electrode and described outer electrode, be formed with groove, in this groove, be provided with insulator,, between the end of a described side's internal electrode and described outer electrode, be formed with groove in described second side, be provided with insulator in this groove, described insulator is lower than described piezoelectrics Young's modulus.
15. multi-layer piezoelectric element as claimed in claim 1 is characterized in that, the conductivity accessory that has the conductive adhesive by net that is embedded with metal or cancellous metallic plate to constitute in the arranged outside of described outer electrode.
16. multi-layer piezoelectric element as claimed in claim 15 is characterized in that, described conductive adhesive is made of the polyimide resin that is dispersed with electroconductive particle.
17. multi-layer piezoelectric element as claimed in claim 16 is characterized in that, described electroconductive particle is a silver powder.
18. injection apparatus, it is characterized in that possessing: have spray-hole accommodating container, be housed in this accommodating container as each described multi-layer piezoelectric element of claim 1～17 and the driving that utilizes this multi-layer piezoelectric element from as described in the needle valve of spray-hole ejection liquid.
Applications Claiming Priority (6)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2003332020A JP4808915B2 (en) | 2003-09-24 | 2003-09-24 | Multilayer piezoelectric element and injection device |
| JP2003-332020 | 2003-09-24 | ||
| JP2003332020 | 2003-09-24 | ||
| JP2003421146A JP4593911B2 (en) | 2003-12-18 | 2003-12-18 | Multilayer piezoelectric element and injection device |
| JP2003-421146 | 2003-12-18 | ||
| JP2003421146 | 2003-12-18 |
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| CNA2004800276571A Division CN1856886A (en) | 2003-09-24 | 2004-09-22 | Multilayer piezoelectric device |
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| CN101504966A true CN101504966A (en) | 2009-08-12 |
| CN101504966B CN101504966B (en) | 2014-02-12 |
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| CNA2004800276586A Pending CN1856887A (en) | 2003-09-24 | 2004-09-22 | Multilayer piezoelectric device |
| CNA2004800276571A Pending CN1856886A (en) | 2003-09-24 | 2004-09-22 | Multilayer piezoelectric device |
| CN200810190350.3A Expired - Fee Related CN101504966B (en) | 2003-09-24 | 2004-09-22 | Multilayer piezoelectric device and ejection apparatus |
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| CNA2004800276571A Pending CN1856886A (en) | 2003-09-24 | 2004-09-22 | Multilayer piezoelectric device |
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| CN107240639A (en) * | 2017-07-27 | 2017-10-10 | 苏州攀特电陶科技股份有限公司 | Prevent actuator, preparation method and the terminal of Crack Extension |
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| JP4706209B2 (en) * | 2004-08-30 | 2011-06-22 | 株式会社デンソー | Multilayer piezoelectric element, manufacturing method thereof, and conductive adhesive |
| WO2007097460A1 (en) * | 2006-02-27 | 2007-08-30 | Kyocera Corporation | Process for producing ceramic member, ceramic member, gas sensor element, fuel cell element, filter element, layer-built piezoelectric element, injector, and fuel injection system |
| US8276567B2 (en) * | 2007-12-26 | 2012-10-02 | Kyocera Corporation | Multi-layer piezoelectric element, and injection apparatus and fuel injection system that employ the same |
| WO2009092584A1 (en) * | 2008-01-23 | 2009-07-30 | Epcos Ag | Piezoelectric multilayer component |
| JP5646989B2 (en) * | 2008-03-21 | 2014-12-24 | 日本碍子株式会社 | Piezoelectric / electrostrictive element and manufacturing method thereof |
| JPWO2010024199A1 (en) * | 2008-08-26 | 2012-01-26 | 京セラ株式会社 | Multilayer piezoelectric element, injection device using the same, and fuel injection system |
| CN102714473A (en) * | 2009-12-21 | 2012-10-03 | 柯尼卡美能达先进多层薄膜株式会社 | Electrical machine conversion element and drive device |
| FR2968418B1 (en) * | 2010-12-03 | 2013-08-16 | Schneider Electric Ind Sas | LED-OPERATING DEVICE AND PUSH-BUTTON COMPRISING SUCH A DEVICE |
| DE102012107341B4 (en) | 2012-08-09 | 2020-07-09 | Tdk Electronics Ag | Method for filling at least one cavity of a multilayer component with a filling material |
| DE102013108753A1 (en) | 2013-08-13 | 2015-02-19 | Epcos Ag | Multi-layer component with an external contact and method for producing a multilayer component with an external contact |
| CN103647021B (en) * | 2013-11-26 | 2018-03-13 | 重庆中镭科技有限公司 | A kind of piezoelectric bimorph piece preparation method |
| JP6270506B2 (en) * | 2014-01-27 | 2018-01-31 | オリンパス株式会社 | Laminated ultrasonic vibration device and ultrasonic medical device |
| CN103991288B (en) * | 2014-05-23 | 2016-02-10 | 北京派和科技股份有限公司 | Piezoelectric ink jet head and comprise the printing device of this piezoelectric ink jet head |
| DE102015117203A1 (en) * | 2015-10-08 | 2017-04-13 | Epcos Ag | pressure sensor |
| KR101847498B1 (en) | 2017-03-07 | 2018-05-28 | 학교법인 송원대학교 | Bending device for implant bar of orthopedics |
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| JPH0529680A (en) * | 1991-07-25 | 1993-02-05 | Hitachi Metals Ltd | Laminated displacement element and manufacture thereof |
| JP3758293B2 (en) * | 1997-04-21 | 2006-03-22 | 株式会社村田製作所 | Multilayer ceramic electronic component and manufacturing method thereof |
| JP2000077733A (en) * | 1998-08-27 | 2000-03-14 | Hitachi Ltd | Laminated piezoelectric element |
| JP4748831B2 (en) * | 1999-04-30 | 2011-08-17 | パナソニック株式会社 | Electronic components |
| JP3881474B2 (en) * | 1999-05-31 | 2007-02-14 | 京セラ株式会社 | Multilayer piezoelectric actuator |
| JP2001210884A (en) * | 2000-01-26 | 2001-08-03 | Kyocera Corp | Stacked type piezoelectric actuator |
| JP2001342062A (en) * | 2000-05-31 | 2001-12-11 | Kyocera Corp | Piezoelectric ceramic, multilayered piezoelectric element and injector |
| JP2002141242A (en) * | 2000-10-31 | 2002-05-17 | Furuya Kinzoku:Kk | Electronic component |
| DE10152490A1 (en) * | 2000-11-06 | 2002-05-08 | Ceramtec Ag | External electrodes on piezoceramic multilayer actuators |
| JP3760770B2 (en) * | 2001-01-05 | 2006-03-29 | 株式会社村田製作所 | Multilayer ceramic electronic component and manufacturing method thereof |
| JP3667289B2 (en) * | 2001-02-27 | 2005-07-06 | 京セラ株式会社 | LAMINATED PIEZOELECTRIC ELEMENT, ITS MANUFACTURING METHOD, AND INJECTION DEVICE |
| JP2002289932A (en) * | 2001-03-22 | 2002-10-04 | Kyocera Corp | Laminated piezoelectric element, manufacturing method therefor, and jetting device |
| JP2003046157A (en) * | 2001-08-01 | 2003-02-14 | Kyocera Corp | Laminated piezoelectric device and its manufacturing method |
| JP2003258328A (en) * | 2002-02-27 | 2003-09-12 | Kyocera Corp | Stacked piezoelectric actuator |
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2003
- 2003-09-24 JP JP2003332020A patent/JP4808915B2/en not_active Expired - Fee Related
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- 2004-09-22 CN CNA2004800276586A patent/CN1856887A/en active Pending
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| CN107240639A (en) * | 2017-07-27 | 2017-10-10 | 苏州攀特电陶科技股份有限公司 | Prevent actuator, preparation method and the terminal of Crack Extension |
Also Published As
| Publication number | Publication date |
|---|---|
| JP4808915B2 (en) | 2011-11-02 |
| CN1856887A (en) | 2006-11-01 |
| CN1856886A (en) | 2006-11-01 |
| CN101504966B (en) | 2014-02-12 |
| JP2005101207A (en) | 2005-04-14 |
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