Piezoelectric device and production method for green compact being molded body of piezoelectric device prior to sintering

Patent metadata

Field	Value
Publication number	US-9608194-B2
Application number	US-201314037956-A
Country	US
Kind code	B2
Filing date	Sep 26, 2013
Priority date	Mar 28, 2011
Publication date	Mar 28, 2017
Grant date	Mar 28, 2017

Abstract

A plurality of piezoelectric device corresponding parts including a green main body part and a green top surface electrode formed on a top surface of the green main body part are placed on a tabular substrate at intervals. Next, a tabular elastic body is pressed from above to the plurality of piezoelectric device corresponding parts, so as to form an inclined part declined toward an outer side in an edge of a top surface of each piezoelectric device corresponding part, and to form a circular arc part at an intersection between the inclined part and a side surface of the piezoelectric device corresponding part. Next, a green side surface electrode is formed on the side surface of each piezoelectric device corresponding part so that the green side surface electrode is connected to the green top surface electrode. Next, this molded body is sintered so that a piezoelectric device is obtained.

First claim

The invention claimed is:

1. A piezoelectric device being a sintered body, comprising:
a main body part comprising a part made of a piezoelectric material, the main body part having a surface comprising a flat top surface part, a flat bottom surface part, and a side surface part connecting the flat top surface part to the flat bottom surface part;
a top surface electrode that covers at least a part of the flat top surface part of the main body part;
a bottom surface electrode that covers at least a part of the flat bottom surface part of the main body part; and
a side surface electrode that covers at least a part of the side surface part of the main body part and connects the top surface electrode to the bottom surface electrode,
wherein Tb/Ta is 1.0 to 5.0, where Ta represents a thickness at a part of the side surface electrode where the thickness becomes minimum, and Tb represents a thickness at a part of the side surface electrode where a radius of curvature of a surface thereof becomes minimum.

2. A piezoelectric device according to claim 1 , wherein:
the part of the side surface electrode where the thickness becomes minimum comprises a center part of the side surface electrode in an up and down direction; and
the part of the side surface electrode where the radius of curvature of the surface thereof becomes minimum comprises a part in a vicinity of a boundary between the side surface electrode and the top surface electrode or the bottom surface electrode.

3. A piezoelectric device according to claim 1 , wherein Tc/Ta is 0.5 to 2.0, where Tc represents a thickness of the top surface electrode or the bottom surface electrode.

4. A piezoelectric device according to claim 1 , wherein:
the main body part comprises a laminated body comprising at least one piezoelectric layer made of the piezoelectric material and at least one internal electrode that are laminated on each other; and
the internal electrode is connected to the side surface electrode.

5. A piezoelectric device according to claim 1 , wherein the main body part has a rectangular parallelepiped shape having a depth of 0.4 to 10.0 mm, a width of 0.2 to 10.0 mm, and a height of 0.3 to 10.0 mm.

6. A production method for a green compact being a molded body prior to sintering of a piezoelectric device being a sintered body,
the piezoelectric device comprising:
a main body part comprising a part made of a piezoelectric material, the main body part having a surface comprising a flat top surface part, a flat bottom surface part, and a side surface part connecting the flat top surface part to the flat bottom surface part;
a top surface electrode that covers at least a part of the flat top surface part of the main body part;
a bottom surface electrode that covers at least a part of the flat bottom surface part of the main body part; and
a side surface electrode that covers at least a part of the side surface part of the main body part and connects the top surface electrode to the bottom surface electrode,
wherein Tb/Ta is 1.0 to 5.0, where Ta represents a thickness at a part of the side surface electrode where the thickness becomes minimum, and Tb represents a thickness at a part of the side surface electrode where a radius of curvature of a surface thereof becomes minimum,

the production method comprising:
a first step of placing a plurality of green compacts on a tabular substrate at intervals, the plurality of green compacts each comprising a green main body part that corresponds to the main body part and a green top surface electrode that is formed on a top surface of the green main body part and corresponds to the top surface electrode;
a second step of pressing an elastic body from above to the plurality of green compacts, so as to form an inclined part declined toward an outer side in an edge of a top surface of each of the plurality of green compacts, and to form a circular arc part at an intersection between the inclined part and a side surface of the each of the plurality of green compacts, the second step being performed after the first step; and
a third step of forming, on the side surface of the each of the plurality of green compacts, a green side surface electrode that corresponds to the side surface electrode so that the green side surface electrode is connected to the green top surface electrode, the third step being performed after the second step.

7. A production method for a green compact according to claim 6 , wherein:
the plurality of green compacts placed on the tabular substrate have the same height, and the elastic body has a plate-like shape;
the elastic body has a hardness of 15 to 50 in Shore hardness A;
the elastic body is pressed by a pressure of 5 to 40 kgf/cm 2 ;
the inclined part has a length of 0.01 to 1.0 mm when the each of the plurality of green compacts is viewed from above;
the inclined part has an inclination angle of 0.1 to 15.0°; and
the circular arc part has a radius of 0.002 to 0.020 mm.

8. A production method for a green compact according to claim 6 , wherein the first step comprises placing the plurality of green compacts on the tabular substrate at intervals by performing a machining process on one tabular green compact placed on the tabular substrate, the one tabular green compact comprising parts that correspond to the plurality of green compacts at intervals.

9. A production method for a green compact being a molded body prior to sintering of a piezoelectric device being a sintered body,
the piezoelectric device comprising:
a main body part comprising a part made of a piezoelectric material, the main body part having a surface comprising a flat top surface part, a flat bottom surface part, and a side surface part connecting the flat top surface part to the flat bottom surface part;
a top surface electrode that covers at least a part of the flat top surface part of the main body part;
a bottom surface electrode that covers at least a part of the flat bottom surface part of the main body part; and
a side surface electrode that covers at least a part of the side surface part of the main body part and connects the top surface electrode to the bottom surface electrode,
wherein Tb/Ta is 1.0 to 5.0, where Ta represents a thickness at a part of the side surface electrode where the thickness becomes minimum, and Tb represents a thickness at a part of the side surface electrode where a radius of curvature of a surface thereof becomes minimum,

the production method comprising:
a first step of placing a plurality of green compacts on a tabular substrate at intervals, the plurality of green compacts each comprising a green main body part that corresponds to the main body part, a green top surface electrode that is formed on a top surface of the green main body part and corresponds to the top surface electrode, and a green bottom surface electrode that is formed on a bottom surface of the green main body part and corresponds to the bottom surface electrode;
a second step of pressing an elastic body from above to the plurality of green compacts, so as to form an inclined part declined toward an outer side in an edge of a top surface of each of the plurality of green compacts, and to form a circular arc part at an intersection between the inclined part and a side surface of the each of the plurality of green compacts, the second step being performed after the first step;
a third step of reversing the plurality of green compacts upside down, placing the plurality of green compacts again on the tabular substrate at intervals, and pressing an elastic body from above to the plurality of green compacts, so as to form an inclined part declined toward an outer side in an edge of a top surface of the each of the plurality

Assignees

• Ngk Insulators Ltd

Inventors

• Ogata Takatomo
• Ito Haruhiko

Classifications

• G03B2205/0061

  using piezoelectric actuators · CPC title

• Y10T29/42

  Piezoelectric device making · CPC title

• G01L1/16 Primary

  using properties of piezoelectric devices · CPC title

• H01L41/0472

  Electricity · mapped topic

• H01L41/08

  Electricity · mapped topic