JP2005243677A - Stacked electronic component and its manufacturing method, and injection apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stacked electronic component wherein a short circuit among internal electrodes can be prevented even in repetitious operation under high voltage, high temperature, and high humidity. <P>SOLUTION: The stacked electronic component is made by stacking a plurality of dielectric layers and a plurality of internal electrodes. The dielectric layers have a thickness of 50 μm or above with the variation in thicknesses being 10 μm or less. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a multilayer electronic component such as a multilayer piezoelectric actuator used for a precision positioning device such as an optical device, a vibration preventing drive element, or a fuel injection drive element of an automobile engine, and a method for manufacturing the same. It is about.

  The piezoelectric plate has an inverse piezoelectric effect that expands and contracts when a voltage is applied. In this case, since the amount of expansion / contraction of each piezoelectric plate is very small, a multilayer piezoelectric actuator formed by laminating a plurality of layers of piezoelectric bodies has been conventionally produced.

  In this laminated piezoelectric actuator, a voltage is applied to a piezoelectric body to extend it by several to several tens of μm, and the actuator is used as a driving force source for the actuator.

  FIG. 1 shows the structure of a conventional multilayer piezoelectric actuator, where (a) is a perspective view and (b) is a side view. The conventional laminated piezoelectric actuator is formed by alternately laminating piezoelectric bodies 1 and internal electrodes 2, and simultaneously firing the piezoelectric bodies 1 and the internal electrodes 2, and the internal electrodes 2 are formed on the four side surfaces of the columnar laminated body 10. The external electrodes 4 are formed on two opposite side surfaces 10b of the columnar laminate 10 that are alternately exposed on the left and right sides, and the internal electrodes 2 are exposed, and are alternately connected to the internal electrodes 2 every other layer.

In such a multilayer electronic component, an internal electrode paste is printed on a ceramic green sheet, and a columnar laminate having a plurality of green sheets coated with the internal electrode paste is produced (for example, see Patent Document 1). .
JP 2001-181055 A

  In recent years, multilayer piezoelectric actuators have been required to be driven by applying a high voltage at a high frequency in order to achieve high responsiveness and large displacement. There is a problem that the end portions of the internal electrodes to which the voltage is applied are short-circuited to reduce driving.

  That is, the conventional multilayer piezoelectric actuator as shown in FIG. 1 is a slurry prepared by mixing a raw material powder and a binder made of an organic polymer, etc., and the slurry is known doctor blade method, calendar roll method, slip casting. A ceramic green sheet to be the piezoelectric body 1 was produced by a tape forming method such as a method, and internal electrodes were printed on the ceramic green sheet and laminated to obtain a columnar laminate. In this molding method, the variation in the thickness of the tape is large due to the mixing of foreign matters, uneven drying, etc., the distance between the internal electrodes 2 may be shortened, and electricity is easily short-circuited between the internal electrodes 2. In particular, when the sheet thickness is increased in order to increase the insulation, the variation becomes large.

  For this reason, in order to achieve the high response and the large displacement as described above, there has been a problem that a short circuit occurs between the internal electrodes when driven by applying a high voltage at a high frequency.

  In particular, when driven under high temperature and high humidity, there is a problem that a short circuit easily occurs between internal electrodes to which different voltages are applied due to migration of electrode components.

  An object of the present invention is to provide a multilayer electronic component that can suppress a short circuit between internal electrodes even when it is repeatedly operated under high voltage, high temperature, and high humidity.

  The multilayer electronic component of the present invention has an electronic component main body formed by laminating a plurality of dielectrics and a plurality of internal electrodes. The thickness of the first dielectric is 50 μm or more and the thickness variation is 10 μm or less. It is characterized by being.

  The multilayer electronic component of the present invention is characterized in that the metal composition in the internal electrode is mainly composed of a Group VIII metal and / or a Group Ib metal, and particularly contains the Group VIII metal in the internal electrode. When the amount is M1 (wt%) and the content of the group Ib metal is M2 (wt%), 0 <M1 ≦ 15, 85 ≦ M2 <100, and M1 + M2 = 100 are satisfied.

  In the multilayer electronic component of the present invention, the group VIII metal is at least one of Ni, Pt, Pd, Rh, Ir, Ru, and Os, and the group Ib metal is at least of Cu, Ag, and Au. It is one or more types.

  In the multilayer electronic component of the present invention, the group VIII metal is at least one of Pt and Pd, and the group Ib metal is at least one of Ag and Au.

  In the multilayer electronic component of the present invention, the group VIII metal is Ni, and the group Ib metal is Cu.

The multilayer electronic component of the present invention is characterized in that an inorganic composition is added to the internal electrode together with a metal composition, and in particular, the inorganic composition is mainly a perovskite oxide composed of PbZrO ₃ —PbTiO _3. It is characterized by being an ingredient.

The multilayer electronic component of the present invention is characterized in that the piezoelectric body has a perovskite oxide as a main component, and in particular, the piezoelectric body has a perovskite oxide composed of PbZrO ₃ —PbTiO ₃ as a main component. It is characterized by that.

  Further, the multilayer electronic component of the present invention has an external electrode on the side surface of the multilayer body, and an internal electrode whose end is exposed on the side surface and an internal electrode whose end is not exposed are alternately configured, A groove is formed in a dielectric portion between the internal electrode and the external electrode where the end portion is not exposed, and the groove is filled with an insulator having a Young's modulus lower than that of the dielectric. To do.

  The method for manufacturing a multilayer electronic component of the present invention can be obtained by producing a dielectric sheet having a thickness of 50 μm or more and a thickness variation of 10 μm or less by tape molding, laminating and firing the internal electrode after printing. Further, the sheet is prepared using a slurry having a slurry viscosity of 15 poise or more, and the sheet contains acrylic and butyral as a binder, and contains at least one of alcohol and toluene as a solvent. It is a feature.

  Further, the injection device of the present invention includes a storage container having an injection hole, the multilayer electronic component stored in the storage container, and a valve that ejects liquid from the injection hole by driving the multilayer electronic component. It is characterized by comprising.

  Since such a multilayer electronic component has a small thickness variation between the internal electrodes that short-circuit the internal electrodes, it can have a high durability performance even under high voltage, high temperature, and high humidity. In particular, with respect to the laminated piezoelectric actuator to which a high voltage is applied, a short circuit between the internal electrodes can be suppressed, and high performance and high reliability can be obtained.

  As described above, according to the multilayer electronic component of the present invention, when the thickness between the internal electrodes is 50 μm or more and the thickness variation is 10 μm or less, the short circuit between the internal electrodes is suppressed, and the high voltage, high temperature It can have high durability performance even under high humidity. In particular, in a stacked piezoelectric actuator to which a high voltage is applied, a short circuit between internal electrodes can be suppressed.

  Embodiments of a multilayer electronic component according to the present invention will be described below with reference to the drawings, taking a multilayer actuator as an example.

  As shown in FIG. 1, the stacked actuator includes two opposing side surfaces 10 b of a quadrangular columnar stacked body 10 formed by alternately stacking a plurality of piezoelectric bodies 1 and a plurality of internal electrodes 2 that are dielectrics. The ends of the internal electrodes 2 are alternately covered with the insulator 3 every other layer, the ends of the internal electrodes 2 that are not covered with the insulator 3 are connected to each of the external electrodes 4, and lead wires are connected to the external electrodes 4. 5 is connected and fixed.

  An internal electrode 2 is disposed between the piezoelectric bodies 1, and a predetermined voltage is applied to each piezoelectric body 1 to cause the piezoelectric bodies 1 to be displaced by a reverse piezoelectric effect.

  In the multilayer piezoelectric actuator of the present invention, the thickness of the piezoelectric body 1, that is, the distance between the internal electrodes 2, is 50 μm or more, preferably 70 μm, more preferably 80 μm or more, and the variation thereof is 10 μm or less, preferably 8 μm or less, Preferably, it is 5 μm or less. This is because if the distance between the internal electrodes 2 is short or the variation thereof is large, a short circuit occurs between the internal electrodes 2 and the laminated piezoelectric actuator is easily damaged.

  Here, the thickness of the piezoelectric body 1, which is a variation in the distance between the internal electrodes 2, is an average value when measured at a plurality of locations, and the variation is a difference between the maximum value and the minimum value.

  Furthermore, since the metal composition in the internal electrode 2 is mainly composed of a Group VIII metal and / or a Group Ib metal, the internal electrode 2 can be formed with a metal composition having high heat resistance. 1 can be fired simultaneously.

  Further, when the content of the group VIII metal in the internal electrode 2 is M1 (wt%) and the content of the group Ib metal is M2 (wt%), 0 <M1 ≦ 15, 85 ≦ M2 <100, M1 + M2 = By satisfying 100, the specific resistance of the internal electrode 2 can be reduced, so that the heat generation of the internal electrode 2 can be suppressed even when the multilayer piezoelectric element is continuously driven for a long time. In addition, since the temperature rise of the multilayer piezoelectric element can be suppressed, the element displacement can be stabilized.

  Furthermore, the group VIII metal is at least one or more of Ni, Pt, Pd, Rh, Ir, Ru, and Os, and the group Ib metal is at least one or more of Cu, Ag, and Au. As a raw material for the internal electrode 2, either an alloy raw material or a mixed powder raw material can be used.

  Furthermore, when the Group VIII metal is at least one of Pt and Pd and the Group Ib metal is at least one of Ag and Au, the internal electrode 2 having excellent heat resistance and oxidation resistance can be obtained. Can be formed.

  Furthermore, since the Group VIII metal is Ni, it is possible to relieve stress caused by displacement during driving and to form the internal electrode 2 having excellent heat resistance.

  Furthermore, since the Ib group metal is Cu, it is possible to relieve stress caused by displacement during driving and to form the internal electrode 2 having excellent thermal conductivity.

  Furthermore, since the adhesion strength at the interface between the internal electrode 2 and the piezoelectric body 1 is increased by adding the inorganic composition together with the metal composition to the internal electrode 2, the peeling at the interface between the internal electrode 2 and the piezoelectric body 1 is suppressed. can do.

Furthermore, since the piezoelectric body 1 is mainly composed of a perovskite oxide made of PbZrO ₃ —PbTiO ₃ , the piezoelectric body 1 and the internal electrode 2 can be fired at the same time. The specific resistance of the electrode 2 can be reduced.

The piezoelectric body 1 is made of, for example, the above-described lead zirconate titanate (Pb (Zr, Ti) O ₃ : hereinafter abbreviated as PZT) or a piezoelectric ceramic material mainly composed of barium titanate (BaTiO ₃ ). ing. The piezoelectric ceramics are those piezoelectric strain constant d ₃₃ indicating the piezoelectric characteristic is high is preferable.

  Furthermore, the internal electrode 2 is exposed on the four side surfaces of the columnar laminate 10 after firing, but at least one side surface has a depth of 50 every other end surface of the piezoelectric body 1 including the end portion of the internal electrode 2. A groove having a width of ˜500 μm and a width of 30 to 200 μm is formed, and the insulator 3 is formed by filling the groove with glass, epoxy resin, polyimide resin, polyamideimide resin, silicone rubber, or the like. Is preferable from the viewpoint of reliability.

  By this insulator 3, the end portions of the internal electrodes 2 are alternately insulated on the two opposite side surfaces 10 b of the columnar laminate 10, and the other end portions of the internal electrodes 2 that are not insulated are connected to the external electrodes. 4 is connected.

  The insulator 3 is made of a material having a low elastic modulus that follows the displacement of the columnar laminate 10, specifically, silicone rubber or the like in order to strengthen the bonding with the columnar laminate 10. Is preferred.

  The external electrode 4 is made of a metal material having conductivity and elasticity such as Ag, Ni, Cu, Al, W, Mo, stainless steel, Fe—Ni—Co alloy, etc., among which the oxidation resistance is good and the conductivity is high. From the viewpoint of being good, Ag, Ni, and stainless steel are preferable. Further, in order to make the external electrode 4 low resistance and to be rich in elasticity so as to follow the displacement of the columnar laminated body 10, a mesh member is provided at a portion connected to the internal electrode 2, and the external electrode The thickness of 4 is desirably about 50 to 500 μm.

  The external electrode 4 may be connected to the internal electrode 2 in a state where the external electrode 4 is pressed against two opposing side surfaces 10b of the columnar stacked body 10 by an external clamping force. Further, the internal electrode 2 may be connected and fixed with solder or the like.

  Further, a low resistance portion of a thin film is formed in advance on two opposing side surfaces 10b of the columnar laminate 10 where the internal electrode 2 is exposed by vapor deposition, sputtering, plating, etc., and the external electrode 4 is formed on the low resistance portion. You may connect.

  Further, the lead wire 5 is connected and fixed to the external electrode 4 with solder or the like. The lead wire 5 has an effect of connecting the external electrode 4 to an external voltage supply unit.

  Then, a direct current of 0.1 to 3 kV / mm is applied to the pair of external electrodes 4 via the lead wires 5 to polarize the columnar laminated body 10, thereby completing the laminated piezoelectric actuator. When the lead wire 5 is connected to an external voltage supply unit and a voltage is applied to the internal electrode 2 via the external electrode 4 with respect to the multilayer piezoelectric actuator, each piezoelectric body 1 is largely displaced by the inverse piezoelectric effect. To do. This function can be used, for example, as an automobile fuel injection device that supplies fuel to an engine.

  That is, an ejection device comprising: a storage container having an ejection port; a multilayered piezoelectric actuator of the present invention housed in the storage container; and a valve that ejects liquid from the ejection hole by driving the multilayer piezoelectric element. Can be configured. In the injection device, as described above, even if it is continuously driven in the multilayer piezoelectric element, the desired displacement does not change effectively, so that the device does not malfunction and has high durability and high reliability. Can be provided.

  Next, a manufacturing method of the multilayer piezoelectric actuator of the present invention will be described.

  The laminated piezoelectric actuator of the present invention is firstly prepared by calcining a piezoelectric ceramic such as PZT, a binder made of an acrylic or butyral organic polymer, an organic solvent such as alcohol or toluene for dissolving the binder. A slurry is prepared by mixing a solvent, a plasticizer such as DBP (diethyl phthalate), DOP (dibutyl phthalate), and the slurry is prepared by a tape forming method such as a well-known doctor blade method, calender roll method, slip casting method or the like. A ceramic green sheet to be the piezoelectric body 1 having a thickness of 50 μm or more and a thickness variation of 10 μm or less is produced.

  The slurry has a viscosity of 15 poise or more, preferably 20 poise, more preferably 25 poise or more. When the thickness of the sheet is increased, the thickness variation increases, but a tape having a uniform thickness can be obtained by forming with a high viscosity. In order to make a slurry with these viscosities, it is preferable to use a binder made of an organic polymer such as acrylic or butyral, and alcohol or toluene to dissolve the binder.

  Next, a binder, a plasticizer, and, if necessary, the piezoelectric ceramic calcined powder and the like are added to and mixed with the silver-palladium powder to produce a conductive paste that forms the internal electrode 2. Printing on the upper surface of the green sheet to a thickness of 1 to 40 μm by screen printing or the like.

  And after laminating | stacking the green sheet with which the electrically conductive paste was printed on the upper surface and cut | disconnecting to arbitrary magnitude | sizes, a binder removal is carried out at predetermined temperature, and the columnar laminated body 10 is baked at 900-1000 degreeC. Make it. At this time, in order to suppress deformation and decomposition that occur during the firing process, it is preferable to fire the materials and the like at the same time, fire in a closed firing pot, or fire in a firing pot of the same material system.

  In order to adjust the shape of the post-fired columnar laminate 10, grinding is performed with a surface grinder or the like. Furthermore, it is preferable to perform processing by lapping or polishing using silicon carbide or alumina abrasive grains, either after grinding or alone.

  As described above, the columnar laminated body 10 formed by alternately laminating the plurality of piezoelectric bodies 1 and the plurality of internal electrodes 2 is manufactured. Further, on the two opposing side surfaces 10b of the columnar laminate 10, the end portions of the internal electrodes 2 are alternately insulated by the insulator 3 every other layer, and the other end portions of the internal electrodes that are not insulated are connected to the external electrodes. 4 is connected, and the lead wire 5 is connected to the external electrode 4, whereby the laminated piezoelectric actuator of the present invention is manufactured.

  In the above embodiment, an actuator in which a plurality of piezoelectric bodies and internal electrodes are stacked has been described. However, the stacked electronic component of the present invention is not limited to a stacked piezoelectric actuator. For example, a multilayer electronic component such as a capacitor can be obtained by using another dielectric instead of the piezoelectric body.

  First, a slurry shown in the table in which a calcined powder of piezoelectric ceramics mainly composed of PZT, a binder made of butyral, a solvent made of IPA-toluene, and a plasticizer were mixed, and after measuring the viscosity, a thickness of 100 μm was measured by a slip casting method. A ceramic green sheet was prepared.

  The conductive paste of the indicated component is printed on one side of the green sheet by a screen printing method to a thickness of 5 μm, the conductive paste is dried, and then a plurality of green sheets to which the conductive paste is applied are 100 sheets. Further, the upper 10 sheets and the lower 20 sheets of the green sheet not coated with the conductive paste were stacked at both ends in the stacking direction of the stacked body.

  Next, this laminate was integrated by applying pressure while heating at 100 ° C., cut into a quadrangular prism with a size of 8 mm × 8 mm, then debindered at 800 ° C. for 10 hours, and at 1000 ° C. for 2 hours. The piezoelectric body 1 and the internal electrode 2 were simultaneously fired for a time, and the columnar laminate 10 shown in FIG. 1 was obtained. At the time of firing, the firing bowl was fired by using a sealed MgO bowl and putting the powder of the same composition together with the laminate.

  The four side surfaces 10a and 10b of the obtained columnar laminate 10 were ground.

  Thereafter, grooves having a depth of 200 μm and a width of 75 μm in the stacking direction are formed on every other side surface 10b of the columnar stacked body 10 so that the end surfaces of the piezoelectric body 1 including the end portions of the internal electrodes 2 are staggered. These grooves were filled with silicone rubber to form the insulator 3, and the end portions of the internal electrode 2 were exposed on the two opposite side surfaces 10b of the columnar laminate 10 every other layer.

  Thereafter, a conductive adhesive made of silver and polyimide resin is applied to the two opposite side surfaces 10b of the columnar laminate 10, and a mesh member is embedded in the conductive adhesive, and heated to 200 ° C. in this state. The external electrode 4 was formed by curing.

  Thereafter, lead wires 5 are connected to both external electrodes 4 by soldering, the outer peripheral surface of the actuator is washed with alcohol, etc., and then surface-treated with a primer or the like to improve the adhesion of the resin, and a method such as dipping After coating the silicone rubber with 1 kV, a polarization voltage of 1 kV was applied to polarize the entire actuator to obtain the multilayer piezoelectric actuator of the present invention shown in FIG.

  As a result of applying a DC voltage of 200 V to the obtained multilayer piezoelectric actuator, each actuator obtained a displacement of 10 μm.

Furthermore, an AC electric field of 0 to +200 V was applied to these laminated actuators at a frequency of 200 Hz, and a driving test was performed at 150 ° C. In the driving test, after the laminated piezoelectric actuator was driven up to 1 × 10 ⁹ cycles, the displacement was measured again, and the variation from the initial displacement was examined. At this time, no abnormality was found when the absolute value of the fluctuation amount was 0.5 μm or less. The displacement is measured by fixing the sample on a vibration isolation table, attaching an aluminum foil to the top of the sample, and averaging the values measured at the central part and peripheral part of the laminated actuator with a laser displacement meter. Evaluated by value.

In addition, the thickness of the piezoelectric body 1 was measured in the cross section of the sample after the driving test. For the measurement, SEM photographs of the cross section were used, and for any five layers of piezoelectric bodies, the thickness of any 10 locations was measured for each layer, and the difference between the maximum value and the minimum value was regarded as variation. The results are as shown in Table 1.

From this table, in Sample No. 1, which is a comparative example, the thickness variation exceeded 10 μm, and therefore a short circuit occurred between the internal electrodes 2 in 1 × 10 ⁷ cycles. In Sample No. 9, the piezoelectric body 1 was thin and the thickness between the internal electrodes was too thin.

  In contrast, in the examples of the present invention (sample numbers 2, 3, 4, 5, 6, 7, and 8) in which the thickness of the piezoelectric body 1 is 50 μm or more and the variation thereof is 10 μm or less, the internal A short circuit between the end portions of the electrode 2 could be suppressed.

  In particular, in the examples (sample numbers 3, 4, 5, 7, and 8) having a thickness of 60 μm or more and a variation of 7 μm or less, the most excellent results were shown.

It is a perspective view which shows the lamination type piezoelectric actuator which is an example of a lamination type electronic component.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Piezoelectric body 2 ... Internal electrode 3 ... Insulator 4 ... External electrode 5 ... Lead wire 10 ... Columnar laminated body 10a ... Side surface 10b ... Side surface

Claims (16)

A multilayer electronic component comprising a plurality of dielectrics and a plurality of internal electrodes laminated, wherein the dielectric has a thickness of 50 μm or more and a thickness variation of 10 μm or less. 2. The multilayer electronic component according to claim 1, wherein the metal composition in the internal electrode is mainly composed of a Group VIII metal and / or a Group Ib metal. When the content of the Group VIII metal in the internal electrode is M1 (wt%) and the content of the Group Ib metal is M2 (wt%), 0 <M1 ≦ 15, 85 ≦ M2 <100, M1 + M2 = 100 The multilayer electronic component according to claim 2, wherein the multilayer electronic component is satisfied. The group VIII metal is at least one of Ni, Pt, Pd, Rh, Ir, Ru, and Os, and the group Ib metal is at least one of Cu, Ag, and Au. Item 4. The multilayer electronic component according to any one of Items 2 to 3. 5. The stacked type according to claim 2, wherein the Group VIII metal is at least one of Pt and Pd, and the Group Ib metal is at least one of Ag and Au. Electronic components. The multilayer electronic component according to claim 2, wherein the Group VIII metal is Ni. The multilayer electronic component according to claim 2, wherein the group Ib metal is Cu. The multilayer electronic component according to claim 1, wherein an inorganic composition is added to the internal electrode together with the metal composition. 9. The multilayer electronic component according to claim 8, wherein the inorganic composition contains a perovskite oxide composed of PbZrO ₃ —PbTiO ₃ as a main component. The multilayer electronic component according to claim 1, wherein the dielectric is mainly composed of a perovskite oxide. The multilayer electronic component according to claim 10, wherein the dielectric is mainly composed of a perovskite oxide made of PbZrO ₃ —PbTiO ₃ . An external electrode is provided on the side surface of the laminate, and an internal electrode whose end is exposed on the side surface and an internal electrode whose end is not exposed are alternately configured, and the internal electrode whose end is not exposed; 12. A groove is formed in a dielectric portion between external electrodes, and an insulator having a Young's modulus lower than that of the dielectric is filled in the groove. Multilayer electronic components. 13. A dielectric sheet having a thickness of 50 [mu] m or more and a thickness variation of 10 [mu] m or less is produced by tape molding, and the internal electrode is printed and then laminated and fired. A method of manufacturing a multilayer electronic component. The method for producing a multilayer electronic component according to claim 13, wherein the sheet is formed using a slurry having a slurry viscosity of 15 poise or more. 15. The method for manufacturing a multilayer electronic component according to claim 13, wherein the sheet contains acrylic and butyral as a binder and contains at least one of alcohol and toluene as a solvent. A storage container having an injection hole, the stacked electronic component according to any one of claims 1 to 12 stored in the storage container, and a valve for ejecting liquid from the injection hole by driving the stacked electronic component An injection device comprising:

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