JPH04263508A - Piezoelectric equipment enclosed in case - Google Patents

Abstract

PURPOSE:To obtain a chip type piezoelectric equipment 10 with a built-in case without using a lead terminal, to obtain an enough shield effect by shield electrodes 18 and 26 even without using a metal case and to considerably reduce cost. CONSTITUTION:A surface acoustic wave element 28 is sealed into an insulator case 12 forming the shield electrodes 18 and 26 on the inner face. The surface acoustic wave element 28 is respectively connected through connection conduction parts 20a, 20b, 22a and 22b to outside electrodes 42a, 42b, 46a and 46b.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric component with a built-in case, and more particularly to a piezoelectric component with a built-in case for high frequencies.

0002

2. Description of the Related Art Conventionally, surface acoustic wave elements, which have a simple structure and can operate in a high frequency range, have been widely used as piezoelectric elements for case-built-in piezoelectric components.

0003

[Problems to be Solved by the Invention] Incidentally, case-built-in piezoelectric components using surface acoustic wave elements have conventionally been provided as components with leads. That is, the surface acoustic wave element is enclosed or sealed in a hermetic case, and the lead terminals must be drawn out to the outside, making the mounting work complicated. Therefore, in case-built-in piezoelectric components using surface acoustic wave elements, like other electronic components,
In order to increase the packaging density and to improve the efficiency of mounting work, it is required to configure the device as a chip type component.

[0004] Therefore, the main object of the present invention is to provide a case-built-in piezoelectric component that is inexpensive and configured as a chip-type component that has a shielding effect.

[0005]

[Means for Solving the Problems] The present invention provides piezoelectric elements,
A piezoelectric component with a built-in case, comprising an insulator case that encloses a piezoelectric element, a shield electrode formed on the inner surface of the insulator case, and an external electrode formed on the outer surface of the insulator case and electrically connected to the piezoelectric element. It is.

[0006]

[Operation] The piezoelectric element enclosed in the insulator case is connected to an external electrode formed on the outer surface of the insulator case. Further, a shield electrode is formed on the inner surface of the insulator case to shield the piezoelectric element.

[0007]

[Effects of the Invention] According to the present invention, the piezoelectric element can be electrically connected to an external circuit by connecting the piezoelectric element to an external electrode. type piezoelectric components can be obtained. Therefore, it is suitable for high-density mounting and improves the efficiency of mounting work.

Furthermore, since an insulating case having a shield electrode formed on its inner surface is used, the piezoelectric element can be shielded in the same way as when a metal case is used, and noise from the outside can be blocked and deterioration of characteristics can be prevented. Therefore, significant cost reductions can be achieved without using an expensive metal case or the like. The above objects, other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

[0009]

[Embodiment] Referring to FIG. 1, a case built-in piezoelectric component 10 of this embodiment is constructed as a surface acoustic wave filter, and includes a housing-shaped insulator case 12 made of, for example, ceramic. . The insulator case 12 includes a flat lower case 14 and a lower case 1 made of ceramic, for example.
4 and a cap-shaped upper case 16 disposed on top of the cap-shaped case 16.

As shown in FIG. 2, a cross-shaped shield electrode 18 is formed approximately at the center of the upper surface of the lower case 14 by, for example, sputtering or vapor deposition. and,
The short side portions of the shield electrode 18 extend to both long side edges of the lower case 14 . Further, near both left corners of the lower case 14, connection conductive parts 20a and 20 for input are provided, respectively.
b is formed. Furthermore, connection conductive portions 22a and 22b for output are formed near both right corners of the lower case 14, respectively.

Further, as shown in FIG. 3, the upper case 16 has a recess 24 that is open downward. A shield electrode 26 is formed on the entire upper surface of the recess 24 by, for example, sputtering or vapor deposition, and is drawn out from approximately the center of the inner surface on the longer side to approximately the center of the lower edge of the longer side. Therefore, shield electrode 26 is electrically connected to shield electrode 18.

Returning to FIG. 1, inside the insulator case 12 formed in this manner is a surface acoustic wave element 2 which becomes a piezoelectric element.
8 is included. That is, the surface acoustic wave element 28 is arranged on the long side of the shield electrode 18. The surface acoustic wave element 28 includes a rectangular piezoelectric substrate 30. Piezoelectric substrate 3
Although not shown, a ground electrode is formed on the back surface of the 0, and is also electrically connected by fixing it on the shield electrode 18 with, for example, a conductive paste. Furthermore, an interdigital transducer 3 is mounted on the top surface of the piezoelectric substrate 30.
2a and 32b are formed, and sound absorbing materials 34a and 34b are formed at both ends of the upper surface of the piezoelectric substrate 30. One end of the interdigital transducer 32a is connected by wire bonding 36a and 36b.
They are electrically connected to connection conductive parts 20a and 20b, respectively. In addition, an interdigital transducer 32
The other end of a is electrically connected to the shield electrode 18 by wire bonding 38. Further, the interdigital transducer 32b is connected to the connecting conductive portion 22 by wire bonding 40a and 40b, respectively.
a and 22b.

As shown in FIGS. 4 and 5, near the left end of both long side outer surfaces of the insulator case 12, there is an input terminal extending from a part of the upper case 16 to a part of the lower case 14. External electrodes 42a and 42b are formed, respectively. External electrodes 42a and 42b are electrically connected to connecting conductive parts 20a and 20b, respectively, as can be seen with reference to FIGS. 2 and 3. In addition, the insulator case 12
Ground electrodes 44a and 44b are formed approximately at the center of both outer surfaces on the longer sides, extending from a portion of the upper case 16 to a portion of the lower case 14, respectively. Ground electrodes 44a and 44b are electrically connected to shield electrodes 18 and 26, respectively. Furthermore, output external electrodes 46a and 46b are formed near the right end of both long side outer surfaces of the insulator case 12, extending from a portion of the upper case 16 to a portion of the lower case 14, respectively. External electrodes 46a and 46b are electrically connected to connecting conductive parts 22a and 22b, respectively.

In the case built-in piezoelectric component 10 formed as described above, the surface acoustic wave element 28 enclosed within the insulator case 12 is connected to the external electrodes 42a, 42a and 22b via the connecting conductive parts 20a, 20b, 22a and 22b. 42b, 46a, and 46b, a chip-type case-built-in piezoelectric component 10 is obtained. Further, since shield electrodes 18 and 26 are formed on the upper surface of lower case 14 and the inner surface of upper case 16, respectively, a sufficient shielding effect can be obtained.

Further, referring to FIG. 6, a case built-in piezoelectric component 50 of another embodiment includes an insulator case 52 made of, for example, ceramic. Insulator case 52 includes a lower case 54 and a lid-shaped upper case 56 disposed on the upper surface of lower case 54 . As shown in FIG. 7, the lower case 54 has a recess 58 that is open upward. Steps 60a and 60b are formed on both long side surfaces of the recess 58, respectively. A shield electrode 6 is provided on the entire bottom surface of the recess 58.
Further, the shield electrode 62 is formed to extend from approximately the center of the long side of the steps 60a and 60b to approximately the center of the upper edge of the long side of the lower case 54 so that it can be drawn out. . Further, as can be seen from FIG. 8, connection conductive portions 64a and 64b for input are formed from the left end of the upper edge of each of the steps 60a and 60b to the vicinity of the left corner of the upper edge of the lower case 54, respectively. Also, the step is 60
Connecting conductive parts 66a and 66b for output are formed from the right end of the upper edge of lower case 54 to the vicinity of the right corner of the upper edge of lower case 54, respectively.

An upper case 56 is arranged on the lower case 54 so as to seal the recess 58. As shown in FIG. 9, a shield electrode 68 is formed on the lower surface of the upper case 56, and is formed approximately at the center of the shield electrode 68 so as to extend to both long side edges. Therefore, shield electrode 68 is electrically connected to shield electrode 62. A surface acoustic wave element 28 similar to that of the previous embodiment is enclosed in the case 52 formed in this manner. That is, the surface acoustic wave element 28 is placed on the shield electrode 62 formed on the recess 58. Then, the wire bonding 3 of the surface acoustic wave element 28
6a and 36b are steps 60a and 60b, respectively.
At the top, it is connected to connecting conductive parts 64a and 64b. Further, the wire bonding 38 is connected to the shield electrode 62 on the upper surface of the step 60b. Further, wire bondings 40a and 40b are connected to connecting conductive parts 66a and 66b, respectively, on steps 60a and 60b.

[0017] On the outer surface of the long side of the case 52,
As in the previous embodiment, the input external electrodes 42a and 4
2b, ground electrodes 44a and 44b, and external output electrodes 46a and 46b are formed. As can be seen with reference to FIGS. 7 and 9, external electrodes 42a and 42b are electrically connected to connecting conductive parts 64a and 64b, respectively, and ground electrodes 44a and 44b are connected to shield electrode 6.
2 and 68, and the external electrodes 46a and 46b are electrically connected to the connecting conductive parts 66a and 66b, respectively.

Note that the shapes of the insulator cases 12 and 52 may be arbitrary. Further, the shield electrodes 26 and 62 are
They may also be formed on the inner surfaces of the upper case 16 and lower case 54, respectively. Further, the shield electrode may be drawn out, for example, from the inner surface of the short side of the insulator cases 12 and 52, and the position where it is drawn out may be arbitrary.

Furthermore, the present invention can be applied not only to surface acoustic wave filters but also to stripline filters and the like.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of essential parts showing an embodiment of the present invention.

FIG. 2 is a perspective view showing a lower case used in the embodiment of FIG. 1;

FIG. 3 is a perspective view showing an upper case used in the embodiment of FIG. 1;

FIG. 4 is a perspective view showing the appearance of the embodiment shown in FIG. 1;

FIG. 5 is a perspective view showing the appearance of the embodiment shown in FIG. 1;

FIG. 6 is a perspective view showing the appearance of another embodiment of the invention.

7 is a perspective view showing a lower case used in the embodiment of FIG. 6. FIG.

8 is a plan view showing the lower case used in the embodiment of FIG. 6. FIG.

9 is a perspective view showing the upper case used in the embodiment of FIG. 6. FIG.

[Explanation of symbols]

10,50
…Piezoelectric components built into the case

Claims (1)

[Claims] 1. A piezoelectric element, an insulator case enclosing the piezoelectric element, a shield electrode formed on the inner surface of the insulator case, and a shield electrode formed on the outer surface of the insulator case and electrically connected to the piezoelectric element. A piezoelectric component with a built-in case and an external electrode.