Thin film piezoelectric element and its manufacturing method, and actuator using the same

A thin film piezoelectric element, comprising:

• a structure including
• (i) a first piezoelectric thin film sandwiched between a first main electrode layer and a first opposed electrode layer, said first main electrode layer and said first opposed electrode layer each having a projection extended away from said first main electrode layer, and
• (ii) a second piezoelectric thin film sandwiched between a second main electrode layer and a second opposed electrode layer in a mirror-symmetrical relationship with respect to said first piezoelectric thin film,
• with said first opposed electrode layer and said second opposed electrode layer being opposed and bonded to each other via an adhesive layer so as to be electrically conductive;
• an insulating resin layer on an outer periphery of said structure, and
• connection wiring arranged on said insulating resin layer in order to establish electrical connection between said projection of said first main electrode layer and said second main electrode layer.

An actuator, comprising:

• first and second thin film piezoelectric elements disposed apart from one another on a substrate at a specific interval, wherein said first and second thin film piezoelectric elements are constructed and arranged to be expanded and contracted in opposite directions, respectively, with each of said first and second thin film piezoelectric elements including:
• (i) a structure including
• (a) a first piezoelectric thin film sandwiched between a first main electrode layer and a first opposed electrode layer, said first main electrode layer and said first opposed electrode layer each having a projection extended away from said first main electrode layer, and
• (b) a second piezoelectric thin film sandwiched between a second main electrode layer and a second opposed electrode layer in a mirror-symmetrical relationship with respect to said first piezoelectric thin film, said second opposed electrode layer having a projection extended away from said second main electrode layer,
• with said first opposed electrode layer and said second opposed electrode layer being opposed and bonded to each other;
• (ii) an insulating resin layer on an outer periphery of said structure;
• and
• (iii) connection wiring arranged on said insulating resin layer in order to establish electrical connection between said projection of said first main electrode layer and said second main electrode layer, and between said projection of said first opposed electrode layer and said projection of said second opposed electrode layer.

An actuator, comprising:

• first and second thin film piezoelectric elements disposed apart from one another on a substrate at a specific interval, wherein said first and second thin film piezoelectric elements are constructed and arranged to be expanded and contracted in opposite directions, respectively, with respective piezoelectric operation generating regions of said first and second thin film piezoelectric elements being in a mirror-symmetrical relationship relative to each other with respect to a center line of the specific interval, and with each of said first and second thin film piezoelectric elements including:
• (i) a structure including
• (a) a first piezoelectric thin film sandwiched between a first main electrode layer and a first opposed electrode layer, said first main electrode layer and said first opposed electrode layer each having a projection extended away from said first main electrode layer, and
• (b) a second piezoelectric thin film sandwiched between a second main electrode layer and a second opposed electrode layer in a mirror-symmetrical relationship with respect to said first piezoelectric thin film,
• with said first opposed electrode layer and said second opposed electrode layer being opposed and bonded to each other via an adhesive layer so as to be electrically conductive;
• (ii) an insulating resin layer on an outer periphery of said structure, and
• (iii) connection wiring arranged on said insulating resin layer in order to establish electrical connection between said projection of said first main electrode layer and said second main electrode layer.

A magnetic recording and reproducing disk device, comprising:

• a magnetic disk;
• a head slider with a magnetic head mounted thereon;
• a flexure for fixing said head slider,
• an arm with said flexure fixed thereon;
• and
• a first positioning device and a second positioning device for positioning said head slider to a predetermined track position on said magnetic disk,
• wherein said first positioning device is a driving device to turn said arm, and said second positioning device is an actuator including first and second thin film piezoelectric elements disposed apart from one another on said flexure at a specific interval, with said first and second thin film piezoelectric elements being constructed and arranged to be expanded and contracted in opposite directions, respectively, so as to finely move said head slider to a predetermined track position on said magnetic disk, and with each of said first and second thin film piezoelectric elements having
• (i) a structure including
• (a) a first piezoelectric thin film sandwiched between a first main electrode layer and a first opposed electrode layer, said first main electrode layer and said first opposed electrode layer each having a projection extended away from said first main electrode layer, and
• (b) a second piezoelectric thin film sandwiched between a second main electrode layer and a second opposed electrode layer in a mirror-symmetrical relationship with respect to said first piezoelectric thin film, said second opposed electrode layer having a projection extended away from said second main electrode layer,
• with said first opposed electrode layer and said second opposed electrode layer being opposed and bonded to each other;
• (ii) an insulating resin layer on an outer periphery of said structure;
• and
• (iii) connection wiring arranged on said insulating resin layer in order to establish electrical connection between said projection of said first main electrode layer and said second main electrode layer, and between said projection of said first opposed electrode layer and said projection of said second opposed electrode layer.

A magnetic recording and reproducing disk device, comprising:

• a magnetic disk;
• a head slider with a magnetic head mounted thereon;
• a flexure for fixing said head slider;
• an arm with said flexure fixed thereon;
• and
• a first positioning device and a second positioning device for positioning said head slider to a predetermined track position on said magnetic disk,
• wherein said first positioning device is a driving device to turn said arm, and said second positioning device is an actuator including first and second thin film piezoelectric elements disposed apart from one another on said flexure at a specific interval, with said first and second thin film piezoelectric elements being constructed and arranged to be expanded and contracted in opposite directions, respectively, so as to finely move said head slider to a predetermined track position on said magnetic disk, with respective piezoelectric operation generating regions of said first and second thin film piezoelectric elements being in a mirror-symmetrical relationship relative to each other with respect to a center line of the specific interval,and with each of said first and second thin film piezoelectric elements having:
• (i) a structure including
• (a) a first piezoelectric thin film sandwiched between a first main electrode layer and a first opposed electrode layer, said first main electrode layer and said first opposed electrode layer each having a projection extended away from said first main electrode layer, and
• (b) a second piezoelectric thin film sandwiched between a second main electrode layer and a second opposed electrode layer in a mirror-symmetrical relationship with respect to said first piezoelectric thin film,
• with said first opposed electrode layer and said second opposed electrode layer being opposed and bonded to each other via an adhesive layer so as to be electrically conductive;
• (ii) an insulating resin layer on an outer periphery of said structure, and
• (iii) connection wiring arranged on said insulating resin layer in order to establish electrical connection between said projection of said first main electrode layer and said second main electrode layer.

A magnetic recording and reproducing disk device, comprising:

• a magnetic disk;
• a head slider with a magnetic head mounted thereon;
• a flexure for fixing said head slider;
• an arm with said flexure fixed thereon;
• and
• a first positioning device and a second positioning device for positioning said head slider to a predetermined track position on said magnetic disk;
• wherein said first positioning device is a driving device to turn said arm, and said second positioning device is an actuator including
• (i) first and second thin film piezoelectric elements disposed apart from one another on said flexture at a specific interval, with said first and second thin film piezoelectric elements being constructed and arranged to be expanded and contracted in opposite directions, respectively, so as to finely move said head slider to a predetermined track position on said magnetic disk, and with each of said first and second thin film piezoelectric elements having:
• (a) a structure including
• (1) a first piezoelectric thin film sandwiched between a first main electrode layer and a first opposed electrode layer, said first main electrode layer and said first opposed electrode layer each having a projection extended away from said first main electrode layer, and
• (2) a second piezoelectric thin film sandwiched between a second main electrode layer and a second opposed electrode layer in a mirror-symmetrical relationship with respect to said first piezoelectric thin film, said second opposed electrode layer having a projection extended away from said second main electrode layer,
• with said first opposed electrode layer and said second opposed electrode layer being opposed and bonded to each other;
• (b) an insulating resin layer on an outer periphery of said structure;
• and
• (c) connection wiring arranged on said insulating resin layer in order to establish electrical connection between said projection of said first main electrode layer and said second main electrode layer, and between said projection of said first opposed electrode layer and said projection of said second opposed electrode layer;
• (ii) connection wiring for establishing connection between said first and second main electrode layers of said first thin film piezoelectric element and said first and second opposed electrode layers of said second thin film piezoelectric element;
• (iii) connection wiring for establishing connection between said first and second opposed electrode layers of said first thin film piezoelectric element and said first and second main electrode layers of said second thin film piezoelectric element;
• and
• (iv) two connection electrode pads for being connected to external terminals.

A magnetic recording and reproducing disk device, comprising:

• a magnetic disk;
• a head slider with a magnetic head mounted thereon;
• a flexure for fixing said head slider;
• an arm with said flexure fixed thereon;
• and
• a first positioning device and a second positioning device for positioning said head slider to a predetermined track position on said magnetic disk;
• wherein said first positioning device is a driving device to turn said arm, and said second positioning device is an actuator including
• (i) first and second thin film piezoelectric elements disposed apart from one another on said flexure at a specific interval, with said first and second thin film piezoelectric elements being constructed and arranged to be expanded and contracted in opposite directions, respectively, so as to finely move said head slider to a predetermined track position on said magnetic disk, with respective piezoelectric operation generating regions of said first and second thin film piezoelectric elements being in a mirror-symmetrical relationship relative to each other with respect to a center line of the specific interval, and with each of said first and second thin film piezoelectric elements having:
• (a) a structure including
• (1) first piezoelectric thin film sandwiched between a first main electrode layer and a first opposed electrode layer, said first main electrode layer and said first opposed electrode layer each having a projection extended away from said first main electrode layer, and
• (2) a second piezoelectric thin film sandwiched between a second main electrode layer and a second opposed electrode layer in a mirror-symmetrical relationship with respect to said first piezoelectric thin film,
• with said first opposed electrode layer and said second opposed electrode layer being opposed and bonded to each other via an adhesive layer so as to be electrically conductive;
• (b) an insulating resin layer on an outer periphery of said structure, and
• (c) connection wiring arranged on said insulating resin layer in order to establish electrical connection between said projection of said first main electrode layer and said second main electrode layer;
• (ii) connection wiring for establishing connection between said first and second main electrode layers of said first thin film piezoelectric element and said first and second opposed electrode layers of said second thin film piezoelectric element;
• (iii) connection wiring for establishing connection between said first and second opposed electrode layers of one said first film piezoelectric element and said first and second main electrode layers of said second thin film piezoelectric element;
• and
• (iv) two connection electrode pads for being connected to external terminals.

A method of manufacturing a thin film piezoelectric element, comprising:

• providing a structure that includes
• (i) a first main electrode layer,
• (ii) a first piezoelectric thin film on said first main electrode layer,
• (iii) a first opposed electrode layer on said first piezoelectric thin film,
• (iv) a first insulating interlayer at a side portion of said first piezoelectric thin film, wherein
• (a) a part of said first main electrode layer defines a projection that is exposed from said first piezoelectric thin film, and
• (b) a part of said first opposed electrode layer defines a projection that is arranged on said first insulating interlayer and extended so as to be laterally offset relative to said first main electrode layer;
• (v) a second opposed electrode layer on said first opposed electrode layer,
• (vi) a second piezoelectric thin film on said second opposed electrode layer,
• (vii) a second main electrode layer on said second piezoelectric thin film, and
• (viii) a second insulating interlayer at a side portion of said second piezoelectric thin film, wherein
• (c) said second main electrode layer and said second piezoelectric thin film are of a shape that is nearly the same as that of said first piezoelectric thin film, and
• (d) a part of said second opposed electrode layer defines a projection that is arranged on said second insulating interlayer and extended so as to be laterally offset relative to said second main electrode layer;
• surrounding said structure with an insulating resin layer;
• and
• forming connection wiring on a side portion of said structure, which connection wiring is to establish electrical connection between said second main electrode layer and said projection of said first main electrode layer, and between said projection of said first opposed electrode layer and said projection of said second opposed electrode layer.

A method of manufacturing a thin film piezoelectric element, comprising:

• providing a structure that includes
• (i) a first main electrode layer,
• (ii) a first piezoelectric thin film on said first main electrode layer,
• (iii) a first opposed electrode layer on said first piezoelectric thin film, wherein
• (a) a part of said first main electrode layer defines a projection that is exposed from said first piezoelectric thin film, and
• (b) a part of said first opposed electrode layer defines a projection that is arranged on a side surface of said first piezoelectric thin film and extended so as to be laterally offset relative to said first main electrode layer;
• (iv) a second opposed electrode layer on said first opposed electrode layer,
• (v) a second piezoelectric thin film on said second opposed electrode layer, and
• (vi) a second main electrode layer on said second piezoelectric thin film, wherein
• (c) said second piezoelectric thin film is of a shape that is nearly mirror-symmetrical with respect to that of said first piezoelectric thin film and covers an entire surface of said second main electrode layer, and
• (d) a part of said second opposed electrode layer defines a projection that is arranged on a side surface of said second piezoelectric thin film and extended so as to be laterally offset relative to said second main electrode layer;
• surrounding said structure with an insulation resin layer;
• and
• forming connection wiring on a side portion of said structure, which connection wiring is to establish electrical connection between said second main electrode layer and said projection of said first main electrode layer, and between said projection of said first opposed electrode layer and said projection of said second opposed electrode layer.