JP4330908B2 - Method for manufacturing ceramic element - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of manufacturing a ceramic element such as a multilayer piezoelectric element or a piezoelectric sensor, and more specifically, electrical connection is made between one end surface side and the other end surface side of a ceramic layer through a through hole. The present invention relates to a method for manufacturing a ceramic element.
[0002]
[Prior art]
In recent years, technological development of a multilayer piezoelectric element which is one of ceramic elements has been actively performed. This type of laminated piezoelectric element is disclosed, for example, in Patent Document 1 below.
[0003]
The multilayer piezoelectric element described in Patent Document 1 is formed by alternately stacking piezoelectric layers patterned with a large number of individual electrodes and piezoelectric layers patterned with common electrodes in the thickness direction of the multilayer piezoelectric element. The aligned individual electrodes are connected by a conductive member through through holes formed in the piezoelectric layer. In such a multilayered piezoelectric element, by applying a voltage between a predetermined individual electrode and a common electrode, an active portion corresponding to the predetermined individual electrode (a portion in which distortion occurs due to the piezoelectric effect) in the piezoelectric layer. ) Can be selectively displaced.
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 2002-254634
[Problems to be solved by the invention]
In ceramic elements such as the multilayer piezoelectric element as described above, between the one end surface side and the other end surface side of the ceramic layer due to the miniaturization of the element itself and the high integration of the electrodes formed on the element. Therefore, a technique capable of reliably achieving electrical connection through a through hole has been desired.
[0006]
Therefore, the present invention has been made in view of such circumstances, and a ceramic element in which electrical connection between the one end surface side and the other end surface side of the ceramic layer is reliably made through a through hole. An object is to provide a manufacturing method.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, according to the method for manufacturing a ceramic element of the present invention, electrical connection is made between one end surface side and the other end surface side of the ceramic layer through a through hole formed in the ceramic layer. A method of manufacturing a ceramic element, the step of forming a ceramic material layer to be a plurality of ceramic layers on the surface of the holding member, the step of thermally shrinking the holding member and the ceramic material layer, and the heat-shrinkable holding member And a step of forming a position reference hole in at least one of the ceramic material layers, a step of forming a through hole in the ceramic material layer with reference to the position reference hole, and a ceramic material layer in which the through holes are formed to a predetermined length And a step of cutting .
[0008]
In this method of manufacturing a ceramic element, after the ceramic material layer is formed on the surface of the holding member, the holding member and the ceramic material layer are thermally contracted before the through hole is formed in the ceramic material layer. As a result, even if the holding member and the ceramic layer are heated in the step after forming the through hole, further heat shrinkage of the holding member and the ceramic layer is almost eliminated. Accordingly, the shape of the through hole can be prevented from being distorted or the formation position of the through hole can be prevented from shifting, and the electrical connection between the one end surface side and the other end surface side of the ceramic layer can be prevented. It becomes possible to carry out reliably through the hall.
[0009]
Here, the ceramic element means an element having a ceramic layer formed of a ceramic material, and includes a multilayer piezoelectric element, a piezoelectric sensor, a capacitor, an inductor, a transformer, a filter, and a combination of these. .
[0010]
In addition, after forming the through hole, the step of printing a paste-like conductive material on the ceramic material layer and the step of drying the conductive material printed on the ceramic material layer at a predetermined drying temperature, the step of heat shrinking Then, it is preferable to heat-shrink the holding member and the ceramic material layer at a temperature higher than the drying temperature. As described above, if the holding member and the ceramic material layer are thermally contracted at a temperature higher than a predetermined drying temperature when the conductive material is dried, the shape of the through hole is distorted when the conductive material is dried. It is possible to prevent the hole formation position from being shifted.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. First, a ceramic element manufactured by the method for manufacturing a ceramic element according to this embodiment will be described.
[0012]
As shown in FIG. 1, the ceramic element according to the present embodiment is a multilayer piezoelectric element 1, which includes a piezoelectric layer (ceramic layer) 3 on which individual electrodes 2 are formed, and a common electrode. 4 piezoelectric layers (ceramic layers) 5 each having 4 formed thereon are alternately laminated, and further sandwiched from above and below by the piezoelectric layers 7 on which the terminal electrodes are formed and the piezoelectric layer 9 serving as a base. Configured.
[0013]
Each of the piezoelectric sheets 3, 5, 7, and 9 is mainly composed of lead zirconate titanate and is formed in a rectangular thin plate shape of “10 mm × 30 mm, thickness 30 μm”. The individual electrode 2 and the common electrode 4 are mainly composed of silver and palladium, and are formed by patterning by screen printing. The same applies to each electrode described below.
[0014]
A large number of individual electrodes 2 are arranged in a matrix on the upper surface of each piezoelectric layer 3. The individual electrodes 2 are separated from each other by a predetermined distance, thereby achieving electrical independence and preventing the influence of mutual vibration. Each individual electrode 2 is connected to a conductive member in a through hole 13 formed in the piezoelectric layer 3 immediately below the outer end portion thereof (excluding the lowermost piezoelectric layer 3).
[0015]
Furthermore, an intermediate electrode 6 for electrically connecting the common electrodes 4 and 4 of the piezoelectric layer 5 positioned above and below is formed on the edge of the upper surface of the piezoelectric layer 3. The intermediate electrode 6 is connected to a conductive member in a through hole 8 formed in the piezoelectric layer 3 immediately below the intermediate electrode 6.
[0016]
An intermediate electrode 16 is formed on the upper surface of each piezoelectric layer 5 so as to face the outer end of each individual electrode 2 of the piezoelectric layer 3 in the thickness direction of the multilayer piezoelectric element 1. (Hereinafter, “the thickness direction of the laminated piezoelectric element 1”, that is, “the thickness direction of the piezoelectric layers 3 and 5” is simply referred to as the “thickness direction”). Each intermediate electrode 16 is connected to a conductive member in a through hole 13 formed in the piezoelectric layer 5 immediately below.
[0017]
Further, a rectangular common electrode 4 is formed on the upper surface of the piezoelectric layer 5. The common electrode 4 is formed in a solid shape so as to overlap with a portion of the piezoelectric layer 3 other than the outer end portion of each individual electrode 2 when viewed from the thickness direction. The common electrode 4 is connected to a conductive member in the through hole 8 formed in the piezoelectric layer 5 so as to face the intermediate electrode 6 of the piezoelectric layer 3 in the thickness direction.
[0018]
An outer electrode 17 is formed on the upper surface of the uppermost piezoelectric layer 7 so as to face each intermediate electrode 16 of the piezoelectric layer 5 in the thickness direction, and the intermediate electrode 6 of the piezoelectric layer 3 in the thickness direction. An external electrode 18 is formed so as to oppose to. Each external electrode 17 is connected to a conductive member in a through hole 13 formed in the piezoelectric layer 7 immediately below it, and the external electrode 18 is connected to the inside of the through hole 8 formed in the piezoelectric layer 7 immediately below it. Connected to the conductive member. A rectangular common electrode 19 is formed on the upper surface of the lowermost piezoelectric layer 9 in a solid shape with a predetermined interval from the outer peripheral portion of the piezoelectric layer 9.
[0019]
The outermost electrodes 17 and 18 in the uppermost layer are provided with a silver baking electrode so as to attach a lead wire for electrical connection to a drive power supply, and function as terminal electrodes of the multilayer piezoelectric element 1.
[0020]
By laminating the piezoelectric layers 3, 5, 7, 9 having the electrode patterns as described above, four individual electrodes 2 are intermediate electrodes in the thickness direction with respect to the outermost electrodes 17 of the uppermost layer. The electrodes 2, 16, and 17 that are aligned with the interposition of 16 are electrically connected by a conductive member in the through hole 13. More specifically, as shown in FIG. 2, the individual electrodes 2 and 2 adjacent to each other in the thickness direction are electrically connected by the conductive member 14 in the through hole 13 with the intermediate electrode 16 interposed therebetween. Become.
[0021]
On the other hand, with respect to the uppermost external electrode 18, the four common electrodes 4 and the lowermost common electrode 19 are aligned with the intermediate electrode 6 interposed in the thickness direction, and the aligned electrodes 4, 6, 18 are arranged. , 19 are electrically connected by the conductive member 14 in the through hole 8.
[0022]
When a voltage is applied between the predetermined external electrode 17 and the external electrode 18 by such electrical connection in the multilayer piezoelectric element 1, the individual electrode 2 and the common electrodes 4 and 19 aligned under the predetermined external electrode 17. A voltage is applied between the two. Thereby, in the piezoelectric layers 3 and 5, as shown in FIG. 2, an electric field is generated in the portion sandwiched between the portions other than the outer end portion of the individual electrode 2 and the common electrodes 4 and 19. The active part 21 is displaced. Therefore, by selecting the external electrode 17 to which the voltage is applied, among the active portions 21 corresponding to the individual electrodes 2 arranged in a matrix, the active portions 21 aligned under the selected external electrode 17 are arranged in the thickness direction. Can be displaced. Such a laminated piezoelectric element 1 is applied to a drive source of various devices that require minute displacement, such as valve control of a micropump.
[0023]
Next, a method for manufacturing the multilayer piezoelectric element 1 described above will be described as a method for manufacturing a ceramic element according to the present embodiment.
[0024]
First, as shown in FIG. 3, a paste is prepared by mixing an organic binder, an organic solvent, or the like with a piezoelectric material mainly composed of lead zirconate titanate, and the paste is stored in a tank 31. Then, while the carrier film (holding member) 32 is wound from the reel 33 to the other reel 33, a green sheet (ceramic material layer) 34 to be the piezoelectric layers 3, 5, 7, 9 is formed by the doctor blade method. It forms on the upper surface of the carrier film 32 (sheet forming process). As the carrier film 32, a transparent PET film having a thickness of 54 μm and a width of 100 mm was used. The thickness of the green sheet 34 formed on the upper surface of the carrier film 32 is 40 μm.
[0025]
After the sheet forming step, as shown in FIG. 4, while the carrier film 32 on which the green sheet 34 is formed is wound from the reel 33 to another reel 33, the carrier film 32 and the green sheet are used using the heating furnace 36. 34 are simultaneously heated to forcibly shrink them (heat treatment step). Thereby, the thermal contraction of the carrier film 32 and the green sheet 34 in the subsequent steps can be prevented, and the formation of through holes and the pattern of electrodes can be performed with high positional accuracy.
[0026]
After the heat treatment step, as shown in FIG. 5, a position reference hole is formed using a punching device 37 while winding the carrier film 32 on which the green sheet 34 is formed from the reel 33 to another reel 33. Through holes 8 and 13 (not shown) are formed at a predetermined position of the green sheet 34 with reference to the position reference hole using a laser processing device 38 (through hole forming step). Note that the position reference hole is formed in the outer edge portion of the green sheet 34 which is a remaining material in a later cutting process, or when there is a blank portion where the green sheet 34 is not formed in the outer edge portion of the carrier film 32. It may be formed in the part.
[0027]
After the through-hole forming step, as shown in FIG. 6, a screen for filling a conductive paste (paste-like conductive material) from the upper surface side of the green sheet 34 into the through-holes 8 and 13 using a screen printing device 39. Printing is performed (first printing step). Subsequently, the carrier film 32 and the green sheet 34 are placed in a dryer to dry and solidify the conductive paste in the through holes 8 and 13 to form the conductive member 14 (first drying step). Before the drying step, the carrier film 32 and the green sheet 34 are heated for a predetermined time at a temperature lower than the drying temperature (heating step). By this heating, the conductive paste is softened, and the conductive paste is reliably spread to the lower end portions in the through holes 8 and 13.
[0028]
After the first drying step, screen printing of the conductive paste is performed on a predetermined position on the upper surface of the green sheet 34 (second printing step). Subsequently, the carrier film 32 and the green sheet 34 are put in a dryer, and the conductive paste is dried and solidified to form the electrodes 2, 4, 17, 19 and the like (second drying step). The conductive paste used in the first and second printing steps was prepared by mixing an organic binder, an organic solvent, or the like with a metal material composed of silver and palladium in a predetermined ratio.
[0029]
After the second drying step, as shown in FIG. 7, the green sheet 34 a having a predetermined length is peeled off from the carrier film 32 using the pickup device 41, and the same stacking order as that of the multilayer piezoelectric element 1 described above is obtained. Thus, the green sheets 34a are laminated and temporarily pressed (lamination process).
[0030]
After the laminating step, each green sheet 34a is thermocompression-bonded by pressing in the laminating direction while heating to produce a laminate green. Subsequently, a plurality of laminated green elements having a predetermined size are cut out from the laminated green, and the cut-out laminated green elements are degreased and fired, and then the laminated piezoelectric element 1 is completed through terminal electrode formation, polarization treatment, and the like. Let
[0031]
Next, the above-described heat treatment process will be described in more detail.
[0032]
In this heat treatment step, it is preferable to thermally shrink the carrier film 32 and the green sheet 34 at a temperature of 90 ° C. or higher and 150 ° C. or lower. And from a viewpoint of a heat contraction effect and manufacturing cost, 2 minutes-5 minutes are preferable for heat processing time.
[0033]
Here, the reason why a temperature of 90 ° C. or higher is preferable when the heat shrinkage is as follows. That is, in the first and second drying steps described above, the conductive paste is dried and solidified at a drying temperature in a range higher than 50 ° C. (preferably 70 ° C. or higher) and lower than 90 ° C. Therefore, if the carrier film 32 and the green sheet 34 are thermally contracted at a temperature of 90 ° C. or higher, the thermal contraction of the carrier film 32 and the green sheet 34 in the drying process can be almost eliminated. , 13 can be prevented from being distorted and the positions of the through holes 8, 13 with respect to the position reference hole can be prevented from being displaced.
[0034]
On the other hand, the reason why a temperature of 150 ° C. or lower is preferable when heat shrinking is as follows. That is, when heated at a temperature higher than 150 ° C., the carrier film 32 may be greatly deformed or melted. Moreover, it is because there exists a possibility that the binder component of the green sheet 34 may change in quality.
[0035]
Thus, by providing the heat treatment step between the sheet forming step and the through hole forming step, even if the carrier film 32 and the green sheet 34 are heated in the steps after the through hole forming step, the carrier film 32 and the green sheet The 34 further heat shrinkage can be almost eliminated.
[0036]
Accordingly, the position reference hole formed by the punching device 37 is prevented from being distorted or the formation position is not shifted. Therefore, the through hole is formed at a predetermined position of the green sheet 34 with reference to the position reference hole. 8, 13 can be formed with high accuracy. Then, the conductive paste filling screen printing in the through holes 8 and 13, the conductive paste screen printing at a predetermined position on the upper surface of the green sheet 34, and the green sheets 34 a in the stacking process are accurately stacked. Is possible. In the case where the position reference hole is provided in the blank portion of the carrier film 32 where the green sheet 34 is not formed, there is a possibility that a large positional shift may occur unless the heat treatment step is provided. In such a case, the heat treatment step is provided. This is particularly effective.
[0037]
In the case where the heat treatment process is performed when the laminated piezoelectric element 1 having 300 individual electrodes 2 (4 rows and 75 columns) formed on the upper surface of the piezoelectric layer 3 of “10 mm × 30 mm, thickness 30 μm” is used. The relative stacking deviation of the piezoelectric layers 3 and 5 in the multilayer piezoelectric element 1 was measured in the case of not implementing. As a result, when the heat treatment step was not performed, the stacking shift was 50 μm to 100 μm, whereas when the heat treatment step was performed, the stacking shift was 20 μm or less.
[0038]
Further, as described above, since the heat shrinkage of the carrier film 32 and the green sheet 34 in the process after the through hole forming process is almost eliminated, the shape of the through holes 8 and 13 formed by the laser processing device 38 is prevented from being distorted. can do. As a result, the conductive member 14 can be reliably formed in the through holes 8 and 13.
[0039]
From the above, according to the method for manufacturing a ceramic element according to the present embodiment, by providing a heat treatment step between the sheet forming step and the through hole forming step, the piezoelectric layer 3 through the through holes 8 and 13. , 5 can be manufactured, and the laminated piezoelectric element 1 in which electrical connection between the upper surface side and the lower surface side is reliably performed can be manufactured.
[0040]
【The invention's effect】
As described above, according to the present invention, it is possible to manufacture a ceramic element in which electrical connection between the one end surface side and the other end surface side of the ceramic material layer is reliably made through the through hole.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view of a multilayer piezoelectric element according to an embodiment.
2 is an enlarged cross-sectional view of the multilayer piezoelectric element shown in FIG. 1 as viewed from a direction orthogonal to the longitudinal direction.
FIG. 3 is a conceptual diagram illustrating a sheet forming process of the present embodiment.
FIG. 4 is a conceptual diagram showing a heat treatment process of the present embodiment.
FIG. 5 is a conceptual diagram showing a through hole forming process of the present embodiment.
FIG. 6 is a conceptual diagram illustrating a first printing process of the present embodiment.
FIG. 7 is a conceptual diagram showing a stacking process of the present embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Laminated piezoelectric element (ceramic element), 3, 5 ... Piezoelectric layer (ceramic layer), 8, 13 ... Through hole, 32 ... Carrier film (holding member), 34 ... Green sheet (ceramic material layer).

Claims (2)

A method of manufacturing a ceramic element in which electrical connection is made between one end surface side and the other end surface side of the ceramic layer through a through hole formed in the ceramic layer,
Forming a plurality of ceramic material layers on the surface of the holding member;
Heat shrinking the holding member and the ceramic material layer;
Forming a position reference hole in at least one of the heat-shrinkable holding member and the ceramic material layer;
Forming a through hole in the ceramic material layer based on the position reference hole ;
And a step of cutting the ceramic material layer in which the through holes are formed into a predetermined length . Printing a paste-like conductive material on the ceramic material layer;
A step of drying the conductive material printed on the ceramic material layer at a predetermined drying temperature, and a step between forming the through hole and cutting the predetermined length .
2. The method of manufacturing a ceramic element according to claim 1, wherein, in the heat shrinking step, the holding member and the ceramic material layer are heat shrunk at a temperature higher than the drying temperature.

Images