DE102008041061B4 - Piezoelectric layer element - Google Patents

Abstract

Piezoelectric layer element (1; 2), with:
a plurality of piezoelectric units (15) stacked on each other by bonding material layers (10), each of said piezoelectric units (15) being formed by alternately laminating piezoelectric material layers (11) made of piezoelectric ceramics which can expand upon voltage application; first electrode support layers (12) each having a first electrode portion (121) forming an inner electrode and second electrode support layers (13) each having a second electrode portion (131) forming an inner electrode;
a first side electrode (17) formed on a first side surface of a laminated body of the plurality of piezoelectric units (15) and electrically connected to the first electrode portions (12); and
a second side electrode (18) formed on a second side surface of the laminated body and electrically connected to the second electrode portions (131), wherein
the piezoelectric layer member (1), when viewed in the laminating direction, includes a piezoactive region (191) in which all of the first and second electrode portions (121, 131) overlap each other and includes a piezoinactive (192) region in which only some of the first and second Electrode portions (121, 131) overlap each other or none overlaps, and
each of the bonding material layers (10) is formed by an adhesive applied on a bonding surface (151) between adjacent two of the piezoelectric units (15),
characterized in that
each of the interconnect material layers (10) includes a separator portion (100) configured to split into at least part of the piezoinactive region (192) when the piezoelectric film element (1) is driven to operate wherein the separating portion (100) is a portion of the bonding material layer (10) broken in at least a part of the piezoinactive region (191).

Description

The invention relates to a laminated piezoelectric element formed by stacking a plurality of piezoelectric units, each of which is made by alternately laminating piezoelectric material layers and electrode support layers.

19 shows a piezoelectric layer element 9, which has been developed so that it has a large piezoelectric shift. As shown in this figure, this piezoelectric layer element 9 is formed by alternately laminating a plurality of piezoelectric units 90 by means of bonding material layers 95. Each piezoelectric unit 90 is constituted by piezoelectric material layers 91 consisting of piezoelectric ceramics which can expand upon voltage application, and electrode support layers 92 each containing an electrode portion 921 or 922 with the electrode portions 921 and the electrode portions 922 alternating with each other. Normally, a pair of side electrodes 931, 932 are formed on the sides of the piezoelectric sheet member 9, with the side electrode 931 leading to the electrode portions 921 and guiding the side electrode 932 to the electrode portions 922. The piezoelectric layer element 9, when viewed in the stacking direction, includes a piezoactive region 910 in which all electrode sections 921 and 922 overlap each other, and a piezoinactive region 911 in which only some of the electrode sections 921 and 922 overlap or overlap each other.

As in 19 and 20 12, the piezoactive region 910 expands and contracts when a voltage is applied to the piezoelectric layer element 9 to make it work, but the piezoactive region 911 scarcely expands or contracts. For example, when forces are applied to the piezoinactive region 911 in the direction indicated by the arrows a and a 'in FIG 20 is specified, the piezoinactive region 911 hardly expands. Accordingly, a voltage is concentrated at the boundary between the piezoactive region 910 and the piezoinactive region 911. When a bonding material layer 95 is formed on the entire portion of a bonding surface of the adjacent piezoelectric units 90 to connect the piezoelectric units 90, a compressive stress is generated at the center of the bonding surface and a tensile stress is generated at the edge of the bonding surface. Therefore, cracks 99 may be generated by mechanical distortion between the piezoelectric material layer 91 and the electrode support layer 92 and in the piezoelectric material layer 91 itself.

A piezoelectric layer element, which has the features specified in the preamble of claim 1, is also known from DE 10 2005 053 465 A1 known.

In order to cope with the above problem, a piezoelectric sheet member 9a has been developed as shown in FIG 21 is shown. In this piezoelectric sheet member 9a, the bonding material layer 95 is formed by an adhesive portion 951 formed by applying an adhesive to a central portion of the bonding surface of the adjacent piezoelectric units 90 and a non-adhesive portion 950 surrounding the adhesive portion 951 and no adhesive contains. For more details on the JP H03-270085 A , the JP H11-274590 A or DE 10 2004 012 282 A1 directed. In the piezoelectric sheet member 9a, the adhesive portion 951 is located in a region (for example, in the piezoactive region 910) that recedes from the outer periphery of the piezoelectric unit 90, and the non-adhesive portion 950 is located so as to surround the adhesive portion 951.

As in 22 As shown, the volume of the gap between the adjacent piezoelectric units 90 in the piezoelectric layer member 9a with the non-adhesive portion 950 at the non-adhesive portion 950 may relatively change as it operates. Therefore, it is considered that the above mechanical distortion can be alleviated.

However, when the side electrodes 931, 932 are formed at its sides, or when its sides are coated with a brazing material (see, for example, FIGS JP H07-106653 A ), the problem that the material of the side electrodes 931, 932 or the brazing material may enter the non-adhesive portion 950. How closer in 23 As shown, when the side electrodes 931, 932 are formed of a conductive resin, the resin component of the conductive resin penetrates from the non-adhesive portion 950 into a connecting portion between the adjacent piezoelectric units. When the side electrodes 931, 932 are formed by a solder, the rosin component of the solder may penetrate into the connecting portion from the non-adhesive portion 950. When the sides of the piezoelectric sheet member are coated with the brazing material, the resin component of the material may penetrate into the non-adhesive portion 950. If the Rosin component or resin component penetrates into the connecting portion, the adjacent piezoelectric units 90 can also stick together at the non-adhesive portion 950 different from the adhesive portion 951. This may cause cracks 99 in the piezoelectric units 90.

In addition, the beat WO 2007/031 700 A1 . DE 10 2004 050 803 A1 and DE 10 2004 031 402 A1 the targeted use of weaker ceramic layers or predetermined breaking points in piezoelectric layer elements, which should be prevented from causing stress cracks in the wrong places.

• einer Vielzahl von piezoelektrischen Einheiten, die mittels Verbindungsmaterialschichten aufeinander geschichtet sind, wobei jede der piezoelektrischen Einheiten durch abwechselndes Aufeinanderschichten von piezoelektrischen Materialschichten, die aus piezoelektrischer Keramik bestehen, die sich bei Spannungsanlegung ausdehnen kann, ersten Elektrodentrageschichten, die einen ersten Elektrodenabschnitt aufweisen, der eine Innenelektrode bildet, und zweiten Elektrodentrageschichten, die einen zweiten Elektrodenabschnitt aufweisen, der eine Innenelektrode bildet, gebildet ist;
• einer ersten Seitenelektrode, die auf einer ersten Seitenfläche eines Schichtkörpers der Vielzahl der piezoelektrischen Einheiten ausgebildet ist und mit den ersten Elektrodenabschnitten elektrisch verbunden ist; und
• einer zweiten Seitenelektrode, die auf einer zweiten Seitenfläche des Schichtkörpers ausgebildet ist und mit den zweiten Elektrodenabschnitten elektrisch verbunden ist, wobei
• das piezoelektrische Schichtelement bei Betrachtung in Aufschichtungsrichtung einen piezoaktiven Bereich, in dem sämtliche der ersten und zweiten Elektrodenabschnitte einander überlappen, und einen piezoinaktiven Bereich enthält, in dem nur einige der ersten und zweiten Elektrodenabschnitte einander überlappen oder keiner überlappt, und
• jede der Verbindungsmaterialschichten durch einen Klebstoff ausgebildet ist, der auf einer Verbindungsfläche zwischen benachbarten zwei der piezoelektrischen Einheiten aufgebracht ist, und einen Trennabschnitt enthält, der so gestaltet ist, dass er sich in zumindest einem Teil des piezoinaktiven Bereichs in zwei Teile trennt, wenn das piezoelektrische Schichtelement so angetrieben wird, dass es arbeitet, wobei der Trennabschnitt ein Abschnitt der Verbindungsmaterialschicht ist, der zumindest in einem Teil des piezoinaktiven Bereichs gebrochen ist.

The invention provides a piezoelectric layer element comprising:

• a plurality of piezoelectric units stacked by bonding material layers, each of the piezoelectric units being formed by alternately stacking piezoelectric material layers made of piezoelectric ceramics which can expand upon voltage application, first electrode support layers having a first electrode portion, an inner electrode and second electrode layers having a second electrode portion forming an inner electrode;
• a first side electrode formed on a first side surface of a laminated body of the plurality of piezoelectric units and electrically connected to the first electrode portions; and
• a second side electrode formed on a second side surface of the laminated body and electrically connected to the second electrode portions, wherein
• the piezoelectric layer element, when viewed in the stacking direction, includes a piezoactive region in which all of the first and second electrode sections overlap each other and includes a piezoelectric active region in which only some of the first and second electrode sections overlap or overlap one another, and
• each of the bonding material layers is formed by an adhesive applied on a bonding surface between adjacent two of the piezoelectric units, and includes a separation portion configured to split into at least a part of the piezoinactive region when the piezoelectric one is in two parts Layer member is driven so that it operates, wherein the separating portion is a portion of the connecting material layer, which is broken at least in a part of the piezoelectric active region.

According to the invention, it is possible to provide a piezoelectric sheet member that can be manufactured while preventing the material of its side electrodes from penetrating into the connecting portion of all the adjacent two of the piezoelectric units at the time of forming the side electrodes, thereby causing generation of To prevent cracks in the piezoelectric units.

Other advantages and features of the invention will be apparent from the following description, including the drawings and claims.

list of figures

• 1 eine Darstellung eines Aufbaus eines piezoelektrischen Schichtelements eines ersten Ausführungsbeispiels der Erfindung;
• 2 eine Darstellung eines Schnittaufbaus des piezoelektrischen Schichtelements des ersten Ausführungsbeispiels;
• 3 eine Darstellung eines Schnittaufbaus eines Verbindungsabschnitts zwischen benachbarten piezoelektrischen Einheiten des piezoelektrischen Schichtelements des ersten Ausführungsbeispiels;
• 4 eine Darstellung, die einen Vorgang zum Ausbilden einer ersten Elektrodendrucklage im ersten Ausführungsbeispiel erläutert;
• 5 eine Darstellung, die einen Vorgang zum Ausbilden einer zweiten Elektrodendrucklage im ersten Ausführungsbeispiel erläutert;
• 6 eine Darstellung, die einen Vorgang zum Aufeinanderschichten der Elektrodendrucklagen im ersten Ausführungsbeispiel erläutert;
• 7 eine Draufsicht auf einen vorläufigen Schichtkörper im ersten Ausführungsbeispiel;
• 8 eine Schnittansicht von 6 entlang A-A in 6;
• 9 eine Darstellung eines Schnittaufbaus eines Zwischenschichtkörpers im ersten Ausführungsbeispiel;
• 10 eine Darstellung eines Schnittaufbaus einer piezoelektrischen Einheit im ersten Ausführungsbeispiel;
• 11 eine Darstellung, die einen Vorgang zum Aufeinanderschichten der piezoelektrischen Einheiten und Ausbilden von Seitenelektroden im ersten Ausführungsbeispiel erläutert;
• 12 eine Darstellung eines Zustands eines Schnittbildes des Verbindungsabschnitts zwischen benachbarten piezoelektrischen Einheiten des piezoelektrischen Schichtelements des ersten Ausführungsbeispiels, wenn es so angetrieben wird, dass es arbeitet;
• 13 eine Darstellung eines Schnittaufbaus des piezoelektrischen Schichtelements des ersten Ausführungsbeispiels, das auf seinen äußersten Seiten mit einer Überzugsschicht ausgebildet ist;
• 14 eine Darstellung eines Schnittaufbaus eines Verbindungsabschnitts zwischen benachbarten piezoelektrischen Einheiten eines piezoelektrischen Schichtelements eines zweiten Ausführungsbeispiels der Erfindung;
• 15 eine Darstellung, die einen Vorgang zum Aufeinanderschichten der piezoelektrischen Einheiten und Ausbilden von Seitenelektroden im zweiten Ausführungsbeispiel erläutert;
• 16 eine Darstellung eines Zustands eines Schnittbildes des Verbindungsabschnitts zwischen benachbarten piezoelektrischen Einheiten des piezoelektrischen Schichtelements des zweiten Ausführungsbeispiels, wenn es so angetrieben wird, dass es arbeitet;
• 17 eine Darstellung, die ein Verfahren zum Messen einer Bruchfestigkeit einer Aufschichtung von zwei piezoelektrischen Einheiten erläutert;
• 18 eine Darstellung, die ein Verfahren zum Messen einer Bruchfestigkeit einer piezoelektrischen Einheit erläutert;
• 19 eine Darstellung eines Schnittaufbaus eines herkömmlichen piezoelektrischen Schichtelements, bei dem auf dem gesamten Abschnitt einer Verbindungsfläche einer piezoelektrischen Einheit eine aus Klebstoff bestehende Verbindungsmaterialschicht ausgebildet ist;
• 20 eine Darstellung eines Schnittaufbaus eines Verbindungsabschnitts des herkömmlichen piezoelektrischen Schichtelements;
• 21 eine Darstellung eines Schnittaufbaus eines anderen herkömmlichen piezoelektrischen Schichtelements, bei dem jeder Verbindungsabschnitt einen klebenden Teilabschnitt und einen nicht klebenden Abschnitt enthält;
• 22 eine Darstellung eines Zustands eines Schnittbildes des anderen herkömmlichen piezoelektrischen Schichtelements; und
• 23 eine Darstellung eines Schnittaufbaus des Verbindungsabschnitts des in 22 gezeigten herkömmlichen piezoelektrischen Schichtelements.

The attached drawings show the following:

• 1 a representation of a structure of a piezoelectric layer element of a first embodiment of the invention;
• 2 a representation of a sectional structure of the piezoelectric layer element of the first embodiment;
• 3 Fig. 10 is an illustration showing a sectional structure of a connecting portion between adjacent piezoelectric units of the piezoelectric sheet member of the first embodiment;
• 4 Fig. 12 is a diagram explaining a process of forming a first electrode pressure sheet in the first embodiment;
• 5 Fig. 12 is a diagram explaining a process of forming a second electrode pressure sheet in the first embodiment;
• 6 a diagram explaining a process for stacking the electrode pressure layers in the first embodiment;
• 7 a plan view of a preliminary composite body in the first embodiment;
• 8th a sectional view of 6 along AA in 6 ;
• 9 a representation of a sectional structure of an intermediate layer body in the first embodiment;
• 10 a representation of a sectional structure of a piezoelectric unit in the first embodiment;
• 11 a representation that is a process of stacking the explained piezoelectric units and forming side electrodes in the first embodiment;
• 12 Fig. 12 is an illustration showing a state of a sectional view of the connecting portion between adjacent piezoelectric units of the piezoelectric sheet member of the first embodiment when it is driven to operate;
• 13 Fig. 10 is an illustration of a sectional structure of the piezoelectric sheet member of the first embodiment formed on its outermost sides with a coating layer;
• 14 Fig. 10 is an illustration showing a sectional structure of a connecting portion between adjacent piezoelectric units of a piezoelectric sheet member of a second embodiment of the invention;
• 15 a diagram explaining a process for stacking the piezoelectric units and forming side electrodes in the second embodiment;
• 16 Fig. 10 is an illustration showing a state of a sectional view of the connecting portion between adjacent piezoelectric units of the piezoelectric laminated member of the second embodiment when it is driven to operate;
• 17 Fig. 11 is a diagram explaining a method for measuring a breaking strength of a stack of two piezoelectric units;
• 18 an illustration explaining a method for measuring a breaking strength of a piezoelectric unit;
• 19 Fig. 12 is an illustration showing a sectional structure of a conventional piezoelectric laminated member in which an adhesive material bonding layer is formed on the entire portion of a bonding surface of a piezoelectric unit;
• 20 a representation of a sectional structure of a connecting portion of the conventional piezoelectric layer element;
• 21 Fig. 10 is an illustration of a sectional structure of another conventional piezoelectric laminated member in which each connecting portion includes an adhesive portion and a non-adhesive portion;
• 22 a representation of a state of a sectional image of the other conventional piezoelectric layer element; and
• 23 a representation of a sectional structure of the connecting portion of the in 22 shown conventional piezoelectric layer element.

First embodiment

It becomes a piezoelectric layer element 1 a first embodiment of the invention explained. As in 1 to 3 is shown, the piezoelectric layer element 1 from a variety of piezoelectric units 15 formed by means of bonding material layers 10 layered on each other. Each piezoelectric unit 15 is through piezoelectric material layers 11 , Electrode-coated layers 12 and electrode-carrying layers 13 formed, which are alternately stacked. The piezoelectric material layer 11 consists of a piezoelectric ceramic that can expand when voltage is applied. The electrode layer 12 has an electrode portion as an inner electrode 121 on, and the electrode layer 13 has an electrode portion as an inner electrode 131 on. The piezoelectric layer element 1 also has a pair of conductive material of existing side electrodes 17 . 18 on. The side electrode 17 leads to the electrode sections 121 , The side electrode 18 leads to the electrode sections 131 ,

As in 2 and 3 is shown contains the piezoelectric layer element 1 in the Aufschichtungsrichtung a piezoactive region 191 in which all electrode sections 121 and 131 overlap each other, and a piezoinactive area 192 in which only some of the electrode sections 121 and 131 overlap or none overlap. The bonding material layer 10 consists of adhesive, which covers the entire section of a bonding surface 151 between the adjacent piezoelectric units 15 is applied. As in 3 is shown in at least part of the piezoinactive region 192 the bonding material layer 10 a separating section 100 intended. The separation section 100 is by breaking the bonding material layer 10 in at least part of the piezoinactive region 192 educated.

The piezoelectric layer element 1 This embodiment will be explained in more detail below. As in 1 to 3 is shown has the electrode layer 12 ( 13 ) as the inner electrode, the electrode portion 121 ( 131 ) and a reduction section 122 ( 123 ), which is for a certain distance between the electrode section 121 ( 131 ) and the outer edge of the piezoelectric unit 15 runs. The electrode layer 12 ( 13 ) is with the side electrode 17 ( 18 ) electrically connected. As the electrode layer 12 ( 13 ) with the reduction section 122 ( 123 ), contains the piezoelectric layer element 1 in the Aufschichtungsrichtung the piezoactive region 191 in which all electrode sections 121 and 131 overlap each other, and the piezoinactive area 192 in which only some of the electrode sections 121 and 131 overlap each other or none overlap (see 2 and 3 ).

The side electrode 17 ( 18 ) has a unit-side electrode 171 ( 181 ), with the electrode sections 121 ( 131 ), and an outside electrode 172 ( 182 ), which are connected to the unit-side electrode 171 ( 181 ) is electrically connected. The outside electrodes 172 ( 182 ) of the piezoelectric units 15 are electrically connected to each other, so that all unit-side electrodes 171 ( 181 ) of the piezoelectric layer element 1 are electrically connected to each other. The unit-side electrode 171 ( 181 ) is formed by Ag pressure. The outside electrode 172 ( 182 ) is made of conductive resin containing epoxy resin and Ag.

The bonding material layer 10 consists of a cured adhesive based on silicone resin. In this embodiment, as the silicone resin-based adhesive, an adhesive which exhibits a breaking strength of 20 MPa after curing is used. In this embodiment, the breaking strength of the piezoelectric unit 15 that is, the smallest value of the breaking strength between the piezoelectric material layers 11 , the breaking strength between the piezoelectric material layer 11 and the electrode portion 121 or 122 and the breaking strength of the piezoelectric material layer 11 even 45 MPa.

In the following description, the breaking strength of the adhesion between the adjacent piezoelectric material layers, the breaking strength of the adhesion between the electrode portion and the piezoelectric material layer, and the breaking strength of the piezoelectric material layer will be referred to as "breaking strength of the piezoelectric unit" while the breaking strength of adhesion between the piezoelectric material layer and the bonding material layer and the breaking strength of the bonding material layer itself may be referred to as "bonding material layer breaking strength". The breaking strength of the piezoelectric unit and the breaking strength of the bonding material layer can be compared with each other by conducting a tensile test as described below with reference to FIG 17 is described. These fracture strengths can be determined by performing the above tensile test as described below.

- tensile test -

First, piezoelectric units of a predetermined size (for example, 7 mm long, 7 mm wide, and 1.8 mm high) and an adhesive to bond them together are prepared. Next, the adhesive is applied to the entire section of the bonding surface 151 between the piezoelectric units 15 applied to glue them together. This will between the piezoelectric units 15 the bonding material layer 10 educated. Next are two hexagonal nuts 160 by a high strength adhesive to each of the top and bottom surfaces of the lamination 199 of the two piezoelectric units 15 glued. After that, the hexagonal nuts 160 pulled in the opposite directions shown by the arrows b and b ', that is, in the directions in which the two piezoelectric units 15 expand. In the process, the piezoelectric units become 15 pulled at a speed of 0.5 mm / min until the lamination of the two piezoelectric units 15 breaks.

If the stratification 199 at the boundary between the bonding material layer 10 and the piezoelectric unit 15 breaks or peels off or if the bonding material layer 10 breaks, then it can be seen that the breaking strength of the connecting material layer 10 lower than that of the piezoelectric unit 15 is.

By the tension in the moment in which the stratification 199 When measured, it is possible to determine the breaking strength of the bonding material layer 10 to investigate. The breaking strength can be calculated by the tensile stress at the moment in which the lamination 199 breaks through the cross-sectional area of the piezoelectric unit (in this case 49 mm ² ) is divided. The tensile stress can be measured, for example, with the precision universal tester AGS manufactured by Shimadzu Corporation. 100B be measured.

In contrast, when the piezoelectric unit 15 That is, when the piezoelectric material layers separate from each other or when the electrode portion and the piezoelectric material layer separate from each other, it can be said that the breaking strength of the bonding material layer is higher than that of the piezoelectric unit 15 is. By measuring the tension in the moment in which the stratification 199 It is possible to break the breaking strength of the piezoelectric unit 15 to investigate.

In this case, the tensile stress can also be measured with the precision universal tester AGS manufactured by Shimadzu Corporation. 100B be measured.

The breaking strength of the piezoelectric unit 15 can also be determined by performing another tensile test, which is described below with reference to 18 is described. Two hexagonal nuts 160 each with an adhesive having a high strength, on the top and bottom surface of a piezoelectric unit 15 predetermined size (for example, 7 mm long, 7 mm wide and 1.8 mm high) glued. Next are the hexagonal nuts 160 drawn in the directions indicated by the arrows b and b ', opposite directions, that is, in the directions in which the piezoelectric unit 15 expands. In this case, the piezoelectric unit 15 pulled at a speed of 0.5 mm / min until the piezoelectric unit breaks. By measuring the tensile stress in the moment in which the piezoelectric unit 15 It is possible to break the breaking strength of the piezoelectric unit 15 that is, the breaking strength of the adhesion between the piezoelectric material layers or the breaking strength of the electrode portion and the piezoelectric material layer or the piezoelectric material layer. The breaking strength can be calculated by the tensile stress at the moment in which the piezoelectric unit 15 breaks through the cross-sectional area of the piezoelectric unit 15 is shared.

Next, referring to 1 to 11 a method for producing the above piezoelectric layer element 1 explained. In this embodiment, the piezoelectric unit becomes 15 manufactured by performing a green sheet manufacturing process, an electrode printing process, a pressing process, a laminated cutting process and a sintering process, which are described below.

- green sheet production process -

First, as the piezoelectric material, a powdery ceramic raw material such as lead zirconate titanate (PZT) is prepared. More specifically, as starting material, lead oxide, zirconia, titania, niobium oxide, strontium carbonate, etc. are prepared and weight-tested to obtain PZT with a target composition. In order to allow evaporation of lead, while lead oxide is mixed so that it is about 1 to 2% richer than the stoichiometric ratio of the desired composition. The PZT of the target composition is mixed dry with a mixer and then pre-sintered at a temperature of 800 ° C - 950 ° C. Then, the presintered powder is wet-ground by a bead mill with pure water, dispersant, etc. The millbase is dried and degreased and then mixed by a ball mill with a solvent, a binder, a plasticizer, a dispersing agent, etc. Thereafter, the resulting slurry is subjected to vacuum defoaming and viscosity adjustment while being stirred by a vacuum processor.

Next, the slurry is formed into a green sheet having a uniform thickness by a squeegee device. Subsequently, the green sheet is punched by a pressing machine or cut by a cutting machine so as to be formed into a predetermined shape and size. The molding of the green sheet can also be done by other methods than the doctor blade method, for example by the extrusion process.

- electrode printing process -

After that, on each preserved green sheet 110 , as in 4 and 5 is shown, an electrode material 120 or an electrode material 130 which forms the electrode portion on the electrode-carrying layer, printed to form two kinds of layers, a first electrode pressure layer 125 and a second electrode pressure layer 135 , The details of forming the first and second electrode pressure layers will be described below 125 and 135 explained.

To the first electrode pressure layer 125 form the electrode material 120 , as in 4 is shown printed on a portion leading to the electrode portion 121 a print area 141 in the green area 110 will (see 1 and 2 ). To the second electrode pressure layer 135 form the electrode material 130 , as in 5 is shown printed on a portion leading to the electrode portion 131 a print area 141 in the green area 110 becomes.

The electrode materials 120 . 130 are printed in such a pattern that the electrode materials 120 . 130 At the time when the later-described laminated cutting operation is performed, come out on the different sides of an interlayer body (to be described later). The electrode materials 120 and 130 are each with intervals 142 printed therebetween so as to avoid being located at portions which are cut in the unit cutting operation performed later. In this embodiment, for the electrode materials 120 . 130 used a paste-like electrode material containing Ag and Pd in a weight ratio Ag / Pd of 7/3.

- pressing process -

Next, as in 6 is shown alternately a desired number of the first and second electrode pressure layer 125 . 135 on each other layered. On the top of the layered layers is a green layer 110 layered on each other, which is not printed with the electrode material. The layers stacked in this manner are heated at 100 ° C and pressed in the laminating direction at 50 MPa to thereby form a preliminary composite 199 train. In 6 The number of layered layers differs from the actual number to facilitate the creation of the drawing.

- laminated body cutting process -

Next becomes the preliminary composite 199 , as in 7 to 9 is shown, in the Aufschichtungsrichtung along cutting lines 143 cut to interlayer body 190 train. The preliminary composite 199 can be cut so that the interlayer body 190 one after the other is formed or that blocks the interlayer body 190 be formed. In this embodiment, the preliminary laminated body becomes 199 cut so that he is the interlayer body 190 one after the other trains. In 8th and 9 gives way to the number of stacked interlayer body 190 from the actual number to facilitate drafting.

- sintering process -

Next up is the green area 110 of the interlayer body 190 contained binder resin by heat by more than 90% by removing the temperature of the interlayer body 190 is increased over a period of 80 hours to 500 ° C and this temperature 5 Is held for hours. Thereafter, the degreased interlayer body 190 sintered to the in 10 shown piezoelectric unit 15 train. The sintering is performed such that the temperature of the defatted interlayer body 190 is gradually increased over a period of 12 hours to 1100 ° C and this temperature 2 Is held for hours and then gradually cooled. As in 10 is shown, the thus prepared piezoelectric unit 15 from the piezoelectric material layers 11 , the electrode tread layers 12 and the electrode-carrying layers 13 formed, which are alternately stacked, each piezoelectric material layer 11 from the sintered green area 110 (please refer 9 ), each electrode layer 12 from the electrode material 120 existing electrode section 121 (please refer 9 ) and each electrode layer 13 from the electrode material 130 existing electrode section 131 (please refer 9 ) having.

After sintering, the obtained piezoelectric unit 15 subjected to a total polishing so that it is 7 mm long, 7 mm wide and 1.8 mm high. Subsequently, on the opposite sides of the piezoelectric unit 15 Ag printed to a pair of unit-side electrodes 171 . 181 train. The electrode sections 121 and 131 each with the unit-side electrodes 171 and 181 electrically connected. In this way, a plurality of the piezoelectric units 15 made with the pair of unit-side electrodes 171 and 181 are formed.

Next, the piezoelectric units made in this way will be described 15 layered to form the piezoelectric layer element. More specifically, on the entire section of the interface 151 every piezoelectric unit 15 an adhesive 101 applied, and these piezoelectric units 15 are then stacked on top of each other and at their connection sections 155 bonded. In this embodiment, the adhesive used is a silicone resin-based adhesive. This silicone resin-based adhesive exhibits a breaking strength of 20 MPa in the above tensile test, which is sufficiently smaller than the breaking strength of the piezoelectric unit 15 ( 45 MPa) is. Next, the adhesive becomes at the connecting portions 155 cured to the bonding material layers made of the adhesive 10 (please refer 1 to 3 ) train. In 11 For example, the number of stacked piezoelectric material layers, electrode layer layers, and piezoelectric units deviates from the actual number to facilitate the drafting.

After that, as in 11 shown is the outside electrode 172 ( 182 ) formed around the unit-side electrodes 171 ( 181 ), which are on the same side of the piezoelectric units 15 are formed, which are connected by means of the bonding material layers. More specifically, the unit-side electrodes 171 ( 181 ) applied a paste-like conductive resin (the resin / silver paste) containing epoxy resin and Ag. At this time, the conductive resin is applied so as to be on the side of the connection portion 155 the adjacent piezoelectric units 15 a gap between the unit-side electrodes 171 ( 181 ) fills. Subsequently, the conductive resin is cured to the outside electrode 172 ( 182 ) train. Similarly, on the opposite side is the outside electrode 182 ( 172 ) educated.

The presence of the outside electrodes makes the electrical connection to the internal electrodes more reliable, and enables the electrical connection to the internal electrodes even if the unit-side electrodes or the outside electrodes partially break can be maintained if the electrical connection between them is maintained.

The thus obtained piezoelectric layer element is made to operate at least once by applying to the outside electrodes 172 and 182 a voltage is applied. When the piezoelectric layer element operates, although the piezoactive region expands 191 in the stratification direction, the piezoinactive region 192 not, so the bonding material layer 10 in the piezoinactive region 192 breaks, thereby separating section 100 (please refer 3 ) train. In this embodiment, the adhesive having the lower breaking strength than the piezoelectric unit 15 is used to the connecting material layers 10 form the breakage occurs in the connecting material layers 10 on.

The operation of the piezoelectric element obtained by the above-described manufacturing method will be described below 1 explained. As in the 1 to 3 is shown, there is the compound material layer 10 covering the adjacent piezoelectric units 15 connects, in the piezoelectric element 1 this embodiment of the adhesive applied to the entire portion of the bonding surface 151 is applied. Thus, the conductive material of the outside electrodes can be prevented from being prevented 172 . 182 at the time of forming the outside electrodes 172 . 182 on the sides of the piezoelectric element 1 in the connecting section 155 between the adjacent piezoelectric units 15 penetrates. Thereby, it is possible to prevent the connection portion 155 stiffened by the conductive material. Accordingly, it can be prevented that due to the rigidity of the connecting portion 155 inside the piezoelectric unit 15 Cracks arise. Since the conductive material can be prevented from entering the connecting portion 155 In addition, it is possible to form the outside electrodes with a higher-strength conductive material. This can prevent the outside electrodes from being broken when the piezoelectric element 1 is working. In addition, the piezoelectric layer element is 1 this embodiment with the separation section 100 provided by breaking the bonding material layer 10 in at least part of the piezoinactive region 192 is trained. As in 12 is shown, the separating section 100 at the piezoinactive area 192 split into two parts when the piezoelectric layer element 1 is working. Thus, the stress concentration at the boundary between the piezoactive region 191 and the piezoinactive region 192 be weakened. Thereby, it can be prevented that within the piezoelectric unit 15 that is within the piezoelectric material layer 11 or between the piezoelectric material layer 11 and the electrode portion 121 ( 131 ) or between the piezoelectric material layers 11 , Cracks arise. Accordingly, the piezoelectric element 1 be driven so that it works with high reliability.

In addition, the piezoelectric element 1 this embodiment with the separation section 100 provided by at least one time driving of the laminated body in which the adjacent piezoelectric units 15 through one on the entire section of the interface 151 applied adhesive, this adhesive having such a breaking strength that the breaking strength of the adhesion between the piezoelectric material layer 11 and the bonding material layer 10 and the breaking strength of the bonding material layer 10 even smaller than the breaking strength of adhesion between the piezoelectric material layers 11 , the breaking strength of adhesion between the piezoelectric material layer 11 and the electrode portion 121 ( 131 ) and the breaking strength of the piezoelectric material layer 11 itself is. The separation section 100 can be easily formed at an appropriate location to the stress concentration at the bonding material layer 10 to suppress. Thus, according to this embodiment, the stress concentration at the boundary between the piezoactive region 191 and the piezoinactive region 192 be sufficiently attenuated.

For the above adhesive, it is desirable to use an adhesive by which the breaking strength of the adhesion between the piezoelectric material layer and the bonding material layer and the breaking strength of the bonding material layer itself are set to 1 to 25 MPa. In general, the breaking strength is the piezoelectric unit described above 30 to 100 MPa. Accordingly, by using such an adhesive, the separation portion can be formed more reliably when the piezoelectric layer element is driven to operate less often.

The above adhesive may be a silicone resin-based adhesive, a urethane resin-based adhesive, a polyester resin-based adhesive, a polyimide resin-based adhesive, a polyamide-imide resin-based adhesive or an epoxy-based adhesive. The adhesives listed above, except for the silicone resin-based adhesive, may have a breaking strength greater than 25 MPa, depending on their type. Each of these adhesives must therefore be selected from various grades that provide a breaking strength of 1 to 25 MPa.

In addition, the bonding material layer becomes 10 in this embodiment, using the silicone resin-based adhesive having a breaking strength of 20 MPa smaller than the breaking strength of 45 MPa of the piezoelectric unit by more than 10 MPa 15 is. This allows the separation section 100 in the bonding material layer 10 with high reliability by a small number of operations of the piezoelectric element 1 train.

As in 13 can be shown on the entire portion of the outermost sides of the piezoelectric element 1 a coating layer 19 may be formed, which consists of an insulating resin, such as a polyester resin. This ensures the electrical insulation capacity of the sides of the piezoelectric element 1 , In this embodiment, the bonding material layer becomes 10 formed by applying to the entire section of the connecting surface 151 between the adjacent piezoelectric units 15 An adhesive is applied, and may therefore because the side of the connecting portion 155 is completely closed, the insulating resin are prevented from entering the connecting portion 155 penetrate. Thus, even in the case that the coating layer consisting of insulating resin is formed, it is possible to prevent the connecting portion 155 becomes stiff.

The insulating resin contains at least one of epoxy resin, polyimide resin, polyester resin, polyamideimide resin, urethane resin and silicone resin.

The separation section 100 Although formed by using an adhesive having a low breaking strength in this embodiment, it can also be formed by using an adhesive having a high breaking strength, as will be explained below 3 ). The separation portion may be formed by causing the piezoelectric sheet member in which the adjacent piezoelectric units are connected to the entire portion of the connection surface to operate at least once. The adhesive, which in its initial state before curing is generally liquid, is gradually hardened by heat application or chemical reaction and eventually becomes solid so that it performs its bonding function when fully cured. Although the adhesive exhibits high breaking strength after fully cured, it has elasticity during curing and exhibits low breaking strength. Thus, it is possible to form the separation portion by making the piezoelectric element work while the adhesive is cured when its breaking strength is smaller than that of the piezoelectric unit to break the bonding material by utilizing the deformability of the piezoelectric element.

It is desirable that the piezoelectric material layer is formed of particles of a piezoelectric ceramic having an average diameter of 1 to 3 μm. In general, such a piezoelectric material layer is formed of particles of a piezoelectric ceramic having an average diameter of 5 to 10 μm. By setting the average diameter of the piezoelectric ceramic particles constituting the piezoelectric material layer to 1 to 3 μm, the breaking strength of the piezoelectric unit can be improved by 3 to 10%. This makes it possible to lower the relative breaking strength of the connecting material layer, so that the separating portion can be easily formed. When the average diameter of the piezoelectric ceramic particles is more than 3 μm, the breaking strength of the piezoelectric device may not be high enough. On the other hand, if the average diameter of the particles is smaller than 1 μm, it may be that the shift rate of the piezoelectric material layer is too small, resulting in insufficient displacement of the piezoelectric layer element. The piezoelectric material layer formed by the piezoelectric particles having the average diameter of 1 to 3 μm may be formed by being sintered at a temperature lower than that required for completely sintering the piezoelectric material layer or for a short period of time. By setting the average particle diameter in this range, it is possible to increase the breaking strength of the piezoelectric unit by 3 to 10%, thereby reducing the breaking strength of the bonding material layer with respect to the piezoelectric unit.

The average diameter of the piezoelectric ceramic particles can be measured by means of a scanning electron microscope. The average diameter is calculated, for example, as an average of the diameters of 10 piezoelectric ceramic particles within a 0.01 mm ² area examined by the scanning electron microscope.

The side electrode is preferably made of conductive resin, solder, conductive metal or a conductive glass material.

By increasing the breaking strength of the piezoelectric material layer, it is possible to relatively reduce the breaking strength of the bonding material layer. In this embodiment, the interlayer body is sintered by raising its temperature to 1100 ° C over a period of 12 hours, this temperature 2 Is held for hours and then it is gradually cooled. The piezoelectric material layer formed by this sintering is formed of piezoceramic particles having an average particle diameter of about 5 μm. It is possible to reduce the average particle diameter by lowering the sintering temperature by 5 to 30% or by shortening the sintering time by 3 to 20%. It is possible to form the piezoelectric unit having a breaking strength of 55 MPa when the piezoelectric material layer is formed by piezoceramic particles having an average particle diameter of about 2.5 μm. When the piezoelectric layer element is manufactured by stacking such piezoelectric units and bonding their bonding surfaces by an epoxy resin-based adhesive having a breaking strength of 50 MPa, the breaking strength of the bonding material layer is smaller than that of this piezoelectric device. Therefore, the above-described separation portion can be formed in the piezoinactive region of the compound material layer by driving the piezoelectric layer member to operate.

Accordingly, since the separating portion can split into two parts in the piezoinactive region in this case as well, when the piezoelectric layer element operates, the stress concentration at the boundary between the piezoactive region and the piezoinactive region can be weakened to thereby cause cracks within the piezoelectric region To prevent unity.

Second embodiment

As in 14 is shown, contains a piezoelectric layer element 2 a second embodiment at the boundary between the bonding material layer 10 and the piezoelectric unit 15 in at least part of the piezoinactive region 192 a release agent layer 25 , The release agent layer 25 formed by curing a release agent-containing silicone resin may bond between the bonding material layer 10 and the piezoelectric unit 15 (Piezoelectric material layer 11 ) suppress. The bonding material layer 10 is formed by an adhesive which, as in the case of the first embodiment, is applied to the entire portion of the bonding surface of the piezoelectric unit 15 is applied. What the other features including the piezoelectric unit 15 is concerned, the second embodiment is the same as the first embodiment.

Next, a method of manufacturing the piezoelectric sheet member of the second embodiment will be described. In this embodiment, the piezoelectric unit becomes 15 as in the case of the first embodiment, by performing a green sheet making process, an electrode printing process, a pressing process, a laminated cutting process, and a sintering process (see FIG 15 ). The piezoelectric unit 15 is from the piezoelectric material layers 11 , Electrode-coated layers 12 and electrode-carrying layers 13 formed, which are alternately stacked as in the first embodiment. The breaking strength of the piezoelectric unit 15 is 45 MPa. On the opposite sides of the piezoelectric unit 15 becomes a pair of unit-side electrodes 171 and 181 educated.

Next, the thus prepared piezoelectric units 15 stacked on top of each other about the piezoelectric layer element 2 train. As in 15 shown is on the interface 151 the piezoelectric unit 15 applied a release agent and then dry cured to the release agent layer 25 train. More specifically, in this embodiment, in the connection surface 151 a silicone resin-containing release agent is applied to the piezoinactive region, along the peripheral edge of the bonding surface 151 the release agent layer 25 train. Subsequently, on the entire section of the connecting surface 151 an adhesive 101 applied. This is the glue 101 also on the surface of the release agent layer 25 applied. In this embodiment, an adhesive based on epoxy resin is used as the adhesive. By conducting the tensile test, it was previously verified that the breaking strength of the epoxy resin-based adhesive 50 MPa is.

After that, as in 15 is shown a plurality of piezoelectric units obtained in this way 15 layered on each other and through the on the connecting surface 151 each connection section 155 applied adhesive 101 bonded. Next, the adhesive is cured to the bonding material layer 10 (please refer 14 ), which at each connecting section 155 consists of the adhesive. It should be noted that in 15 and in the later explained 19 the number of stacked piezoelectric material layers, electrode layer layers and piezoelectric units deviates from the actual number to facilitate the drawing preparation.

Next, as in 15 is shown, the outside electrodes 172 ( 182 ) formed around the unit-side electrodes 171 ( 181 ) electrically connect to each other on the same side of the piezoelectric units 15 are formed, which are connected by means of the bonding material layers. The outside electrodes 172 . 182 are formed in the same manner as in the first embodiment, around the piezoelectric layer element 2 to finish.

As in 14 and 16 is shown contains the piezoelectric layer element 2 the release agent layer 25 to bond between the bonding material layer 10 and the piezoelectric unit 15 (Piezoelectric material layer 11 ) to suppress. When the piezoelectric layer element 2 is driven so that it works at least once, breaking the bonding material layer 10 accordingly at the release agent layer 25 to thereby form the separation section 100 (please refer 16 ) train. In this embodiment, the breakage of the bonding material layer occurs 10 at the boundary between the bonding material layer 10 and the piezoelectric unit (the release agent layer 25 ).

In this embodiment, an epoxy resin-based adhesive having a high breaking strength is used around the bonding material layer 10 train. In the case that the bonding material layer 10 is formed using the epoxy resin-based adhesive, the breaking strength is the bonding material layer 10 about 50 MPa, which is higher than the breaking strength of about 45 MPa of the piezoelectric unit 15 is. According to this embodiment, it is due to the presence of the partitioning section 100 passing through the release agent layer 25 realized, also in this case possible, the emergence of cracks within the piezoelectric unit 15 to prevent when the piezoelectric element 2 is driven so that it works.

As explained above, the fact that in the piezoelectric layer element 2 this embodiment in the piezoinaktive area 192 the release agent layer 25 is provided, the adhesive force between the piezoelectric unit 15 and the bonding material layer 10 much lower (see 14 ). By the concentration of stress inside the piezoelectric layer element 2 arises when the piezoelectric element 2 is driven so that it works, therefore, between the bonding material layer 10 and the piezoelectric unit 15 (between the bonding material layer 10 and the release agent layer 25 ) in the piezoinactive region 192 the separation section 100 educated. When the piezoelectric layer element 2 works, can thereby, that the separating section 100 split into two parts, the stress concentration at the boundary between the piezoactive region 191 and the piezoinactive region 192 be weakened. This prevents the formation of cracks within the piezoelectric unit 15 ,

The piezoelectric layer element 2 This embodiment may be coated on its sides with an insulating resin, such as a polyester resin, as in the case of the first embodiment. Since the bonding material layer is formed on the entire surface between the adjacent piezoelectric units as in the first embodiment, the sides of the bonding portion are completely closed. Accordingly, it is possible to prevent the penetration of the insulating resin into the connecting portion, thereby preventing the connecting portion from becoming rigid.

In the above-described embodiments, the number of the piezoelectric material layers stacked in the piezoelectric unit is preferably 10 to 100. If the number of the stacked piezoelectric material layers is less than 10, the shift generation efficiency of the piezoelectric layer element is smaller because the ratio of the number of layers which are not between the internal electrodes (that is, the top and bottom layers of each piezoelectric unit) to the number of all layers contained in the piezoelectric layer element is large. On the other hand, when the number of piezoelectric material layers stacked in the piezoelectric unit is larger than 100, for actual use (for example, in a fuel injection device of an internal combustion engine), a single piezoelectric unit is sufficient in most cases. In addition, in this case, although the induced voltage in the piezoelectric layer element is attenuated as described above, it may exceed an allowable level. The number of piezoelectric material layers stacked on each other in the piezoelectric unit is more preferably 20 to 80.

The preferred embodiments discussed above are exemplary of the invention, which is described solely by the following claims. It is understood that modifications of the preferred embodiments may be made as would occur to those skilled in the art.

Claims (13)

A piezoelectric laminated member (1; 2) comprising: a plurality of piezoelectric units (15) stacked by bonding material layers (10), each of the piezoelectric units (15) being formed by alternately laminating piezoelectric material layers (11) made of piezoelectric material Ceramics that can expand when voltage application, first electrode layers (12), the each having a first electrode portion (121) forming an inner electrode and second electrode support layers (13) each having a second electrode portion (131) forming an inner electrode; a first side electrode (17) formed on a first side surface of a laminated body of the plurality of piezoelectric units (15) and electrically connected to the first electrode portions (12); and a second side electrode (18) formed on a second side surface of the laminated body and electrically connected to the second electrode sections (131), the piezoelectric layer element (1) having a piezoactive region (191) in which all of them are viewed in the laminating direction the first and second electrode portions (121, 131) overlap each other and include a piezoactive (192) region in which only some of the first and second electrode portions (121, 131) overlap or overlap each other, and each of the bonding material layers (10) an adhesive is formed on one connecting surface (151) is applied between adjacent two of the piezoelectric units (15), characterized in that each of the bonding material layers (10) includes a separating portion (100) which is designed such that it is in separates at least part of the piezoinactive region (192) into two parts, when the piezoelectric sheet member (1) is driven to operate, the separation portion (100) being a portion of the bonding material layer (10) broken in at least a part of the piezoinactive region (191). Piezoelectric layer element (1, 2) according to Claim 1 wherein the separation portion (100) is a portion of the bonding material layer (10) broken in its interior or at a boundary between the bonding material layer (10) and the piezoelectric unit (15). Piezoelectric layer element (1) according to Claim 1 wherein the separating portion (100) is formed by driving the laminated body at least once, in which all the adjacent two of the piezoelectric units (15) are bonded to the entire portion of the connecting surface (151) by the adhesive, which provides a breaking strength of adhesion between all adjacent two of the piezoelectric material layers (11), a breaking strength of the adhesion between each of the first and second electrode portions (121, 131) and each of the piezoelectric material layers (11), and a breaking strength of the piezoelectric material layers (11) smaller by a predetermined value a breaking strength of the adhesion between each of the piezoelectric material layers (11) and each of the bonding material layers (10) and a breaking strength of the bonding material layers (10). Piezoelectric layer element (1) according to Claim 3 , wherein the predetermined value is more than 5 MPa. Piezoelectric layer element (1) according to Claim 3 wherein the adhesive provides that a breaking strength of the adhesion between each of the piezoelectric material layers (11) and each of the bonding material layers (10) and a breaking strength of the bonding material layers (10) is in a range of 1 to 25 MPa. Piezoelectric layer element (1) according to Claim 1 wherein the separating portion (100) is formed by driving the laminated body at least once in which all the adjacent two of the piezoelectric units (15) have been bonded to each other at the entire portion of the connecting surface (151) by the adhesive before the adhesive has completely hardened. Piezoelectric layer element (2) according to Claim 1 further comprising a release agent layer (25) located at a boundary between each of the bonding material layers (10) and each of the piezoelectric units (15) in at least a part of the piezoinactive region (192) to prevent adhesion therebetween. Piezoelectric layer element (2) according to Claim 7 wherein the release agent layer (25) is formed by curing a silicone resin or fluorine resin-containing release agent applied to the boundary on at least a portion of the piezoinactive region (192). Piezoelectric layer element (1, 2) according to Claim 1 wherein each of the piezoelectric material layers (11) is formed of piezoelectric particles having an average particle diameter of 1 to 3 μm. Piezoelectric layer element (1, 2) according to Claim 1 wherein the first and second side electrodes (17, 18) are each made of either conductive resin, solder, conductive metal or conductive glass. Piezoelectric layer element (1, 2) according to Claim 1 wherein the first side electrode (17) has, for each of the piezoelectric units (15), a first unit-side electrode (171) electrically connected to the provided first electrode portions (121) and a first outside electrode (172) connected to the first first unit-side electrodes (171) each piezoelectric unit (15) is electrically connected, and the second side electrode (18) for each of the piezoelectric units (15) has a second unit-side electrode (181) electrically connected to the provided second electrode portions (131) and a second outside Electrode (182) electrically connected to the second unit-side electrodes (181) of all the piezoelectric units (15). Piezoelectric layer element (1, 2) according to Claim 1 wherein the first and second side surfaces on which the first or second side electrodes (17, 18) are formed are each covered with insulating resin. Piezoelectric layer element (1, 2) according to Claim 12 wherein the insulating resin contains at least one of epoxy resin, polyimide resin, polyester resin, polyamideimide resin, urethane resin and silicone resin.

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