PIEZOELECTRIC VIBRATING DEVICES AND METHODS FOR MANUFACTURING SAME

• US 20120049695A1
• Filed: 08/19/2011
• Published: 03/01/2012
• Est. Priority Date: 08/24/2010
• Status: Active Grant

• Current Assignee: Nihon Dempa Kogyo Company Limited
• Original Assignee: Nihon Dempa Kogyo Company Limited
• Inventors: Ichikawa, Ryoichi
• Granted Patent: US 8,549,717 B2
• Time in Patent Office: Days
• US Class Current: 310/344
• CPC Class Codes: H03H 3/02 for the manufacture of piezoelectric or electrostrictive resonators or networks H03H3/08 takes precedence
• CPC Class Codes: H03H 9/1014 the enclosure being defined by a frame built on a substrate and a cap, the frame having no mechanical contact with the BAW device
• CPC Class Codes: Y10T 29/42 Piezoelectric device making
• CPC Class Codes: Y10T 29/49155 Manufacturing circuit on or in base
• CPC Class Codes: Y10T 29/49798 Dividing sequentially from leading end, e.g., by cutting or breaking

Abstract

Methods are disclosed for manufacturing piezoelectric vibrating devices that do not contain any unwanted gas or water vapor inside the devices. In an exemplary method, a base wafer is prepared including multiple package bases each having a first main surface and a second main surface. The base wafer also includes a pair of through-holes disposed between adjacent package bases of the base wafer. A piezoelectric vibrating piece is placed on each package base. A lid wafer is prepared that includes multiple package lids. A sealing material is applied to the base wafer or lid wafer in peripheral bands used for bonding the bases and lids together and defines respective interior cavities. The band of sealing material includes a communicating groove that communicates from the inner cavity to the first through-hole. The base wafer and lid wafer are subject to heat and compression to effect bonding. Meanwhile, the cavities are allowed to ventilate through the communicating grooves and through-holes to ensure that the cavities have a desired vacuum level or inert gas contents before completion of sealing.

Claims

1. A method for manufacturing a piezoelectric device, comprising:

preparing a base wafer including multiple package bases each having a first main surface including respective external electrodes and a second main surface opposite the first main surface, the second main surface including a respective peripheral sealing surface, the base wafer also defining at least a pair of respective through-holes located between adjacent package bases wherein each through-hole extends from the first main surface to the second main surface, each package base when assembled with a package lid forming a respective package defining an interior cavity;

attaching a respective piezoelectric vibrating piece to each package base, each vibrating piece including a respective pair of excitation electrodes;

preparing a lid wafer including multiple package lids, each package lid having a first main surface and a second main surface opposite the first main surface, the second main surface including a respective peripheral sealing surface;

applying a sealing material onto the peripheral sealing surfaces of the package bases or onto the peripheral sealing surfaces of the package lids, the sealing material being applied as a continuous circumferential band having a predetermined width and including a communicating groove allowing temporary pneumatic communication to and from the interior cavity via the through-hole; and

in a vacuum or inert-gas atmosphere, allowing gaseous exchange to and from the cavities via the respective communicating grooves and through-holes while applying heat and compression, the heat and compression bonding the wafers together while allowing flow of sealing material into at least a portion of the communicating grooves sufficient to seal the cavities after the gaseous exchange.

2. The method of claim 1, further comprising forming a metal film on respective interior surfaces of the through-holes, the metal film connecting together each excitation electrode with a respective external electrode.

3. The method of claim 1, wherein the sealing material is an adhesive comprising a glass that melts between 350°

C. to 410°

C.

4. The method of claim 1, further comprising, after bonding the wafers together, cutting the bonded wafers along pre-established scribe lines to release individual piezoelectric vibrating devices, the scribe lines being located so as to allow cutting across respective communicating grooves.

5. The method of claim 4, wherein the communicating grooves expand in width from the respective interior cavities to the scribe lines.

6. The method of claim 1, further comprising, after bonding the wafers together, cutting the bonded wafers along pre-established scribe lines to release individual piezoelectric vibrating devices, the communicating grooves being located so as to extend from the scribe lines to the respective interior cavities.

7. The method of claim 6, wherein the communicating grooves increase in width from the respective interior cavities to the scribe lines.

8. The method of claim 1, wherein each communicating groove has at least a portion having a width that is in a range of 10% to 30% of the width of the band of sealing material.

9. The method of claim 1, wherein:

the package base has a rectangular plan profile;

a respective through-hole is located on each corner of the rectangular profile;

the interior cavity has a rectangular shape with opposing short sides and opposing long sides; and

each communicating groove extends from a respective long side of the rectangular cavity to the through-hole.

10. The method of claim 1, wherein:

the package base has a rectangular plan profile with opposing short sides and opposing long sides;

a respective through-hole is located between adjacent short sides;

the interior cavity has a rectangular shape; and

each communicating groove extends from a respective long side of the rectangular cavity to the through-hole.

11. A method for manufacturing a piezoelectric device, comprising:

preparing a base wafer including multiple package bases each having a first main surface including respective external electrodes and a second main surface opposite the first main surface, the second main surface including a respective peripheral sealing surface, the base wafer also defining at least a pair of first respective through-holes located between adjacent package bases, wherein each first through-hole extends from the first main surface to the second main surface, each package base when assembled with a piezoelectric frame and package lid forming a respective package defining an interior cavity;

preparing a piezoelectric wafer including multiple piezoelectric frames, each piezoelectric frame including a respective piezoelectric vibrating piece attached to and surrounded by an outer frame, each vibrating piece having respective excitation electrodes, a first peripheral sealing surface, and a second peripheral sealing surface, the piezoelectric wafer defining at least a pair of respective second through-holes located between adjacent outer frames, wherein each second through-hole extends from the first peripheral sealing surface to the second peripheral sealing surface;

preparing a lid wafer including multiple package lids each having an outer main surface and an inner main surface, the inner main surface including a peripheral sealing surface;

applying a sealing material on at least one of the peripheral sealing surface of the inner main surface of each lid and the first peripheral sealing surface of each outer frame, and on at least one of the second peripheral sealing surface of each outer frame and the peripheral sealing surface of the second main surface of each base, the sealing material being applied as a continuous band having a predetermined width and including a communicating groove allowing temporary pneumatic communication to and from the interior cavity via the first through-holes or second through-holes; and

in a vacuum or inert-gas atmosphere, allowing gaseous exchange to and from the cavities via the communicating groove and respective through-holes while applying heat and compression, the heat and compression bonding the wafers together while allowing flow of sealing material into at least a portion of the communicating grooves sufficient to seal the cavities after the gaseous exchange.

12. A piezoelectric device, comprising:

a package base including an inner main surface and an outer main surface, the outer main surface including external electrodes and the inner main surface comprising a peripheral bonding region;

a respective edge-surface electrode connected to each external electrode, each edge-surface electrode being located on an outer edge of the package base and extending on said outer edge between the inner and outer main surfaces;

a piezoelectric vibrating piece supported by the package base, the vibrating piece including a respective excitation electrode connected to each edge-surface electrode;

a package lid bonded to the package base to form an interior cavity enclosing the piezoelectric vibrating piece, the package lid including an inner main surface and an outer main surface, the inner main surface comprising a peripheral bonding region; and

a sealing material disposed as a band on the respective peripheral bonding regions of the package base and package lid to bond the package base and lid together, the bands of sealing material having a predetermined width in the peripheral bonding regions and defining at least one communicating groove extending therein between the interior cavity and at least one of the first edge-surface electrodes, the communicating groove being at least partially filled with the sealing material to seal the interior cavity hermetically.

13. The piezoelectric device of claim 12, wherein:

the outer frame and package base each have a respective rectangular plan profile including a respective castellation on each corner thereof; and

the second edge-surface electrodes are formed on respective corner castellations.

14. The piezoelectric device of claim 13, wherein:

the outer frame and package base each have a respective rectangular plan profile including a respective castellation on each corner thereof; and

the second edge-surface electrodes are formed on respective corner castellations.

15. The piezoelectric device of claim 12, wherein:

the outer frame and package base each have a respective rectangular plan profile including a respective castellation on each of two sides thereof; and

the second edge-surface electrodes are formed on respective edge castellations.

16. A piezoelectric device, comprising:

a package base including an inner main surface and an outer main surface, the outer main surface including external electrodes and the inner main surface comprising a peripheral bonding region;

a respective first edge-surface electrode connected to each external electrode, each first edge-surface electrode being located on an outer edge of the package base and extending on said outer edge between the inner and outer main surfaces;

a piezoelectric frame including a piezoelectric vibrating piece surrounded by an outer frame, the vibrating piece having first and second main surfaces each including a respective peripheral bonding region, the peripheral bonding region of the first main surface being bonded to the peripheral bonding region of the package base;

a respective second edge-surface electrode connected to each excitation electrode, each second edge-surface electrode being located on an outer edge of the outer frame and extending on said outer edge between the first and second main surfaces of the outer frame;

a package lid including an inner main surface and an outer main surface, the inner main surface including a peripheral bonding region that is bonded to the peripheral bonding region of the second main surface of the frame to form an interior cavity enclosing the piezoelectric vibrating piece; and

a first sealing material disposed as a band having a predetermined width between the peripheral bonding region of the package lid and the peripheral bonding region of the second main surface of the outer frame, and a second sealing material disposed as a band at a predetermined width between the peripheral bonding region of the package base and the peripheral bonding region of the first main surface of the outer frame so as to bond the package lid, frame, and package base together, the bands of sealing material having predetermined widths in the respective peripheral bonding regions and defining at least one communicating groove extending therein between the interior cavity and at least one of the first edge-surface electrodes, the communicating groove being at least partially filled with the sealing material to seal the interior cavity hermetically.

17. The piezoelectric device of claim 16, wherein:

the outer frame and package base each have a respective rectangular plan profile including a respective castellation on each of two sides thereof; and

the second edge-surface electrodes are formed on respective edge castellations.