JPH01227515A - Piezoelectric oscillator - Google Patents

Abstract

PURPOSE:To execute a miniaturization, to reduce a cost, and to improve an electric characteristic by fixing one edge side main surface of a rectangular crystal piece onto the main surface of a base. CONSTITUTION:First and second space parts 17 and 18 are provided at one main surface side of a substrate 12, divided electrode layers 19a and 19b are formed on the substrate surface of the first space part 17, and connecting electrodes 20a and 20b are extended from surface both edge sides to a back surface. One edge side surface of a crystal piece 11 is surface-faced onto the substrate surface of the second space part 18 and fitted by a conductive adhesive. At such a time, respective leader electrodes 16a and 16b of a pair of exciting electrodes 15a and 15b are electically connected corresponding to the divided electrode layers 19a and 19b, respectively. Since only one edge side of the crystal piece 11 is housed in the second space part 18 and it is fitted, the other side is made into a free edge, and even when the substrate 12 is expanded or contracted by a thermal expansion, the distortion does not work directly to the crystal piece 11. Thus, adaptations to the miniaturization and the cost reduction can be executed, and a workability and the electric characteristic can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Uses of the Invention) The present invention is applied to a piezoelectric vibrator in a thickness-shear vibration mode, and particularly relates to a crystal vibrator that is suitable for miniaturization and has good temperature characteristics.

(Background of the Invention) A crystal resonator in a thickness-shear vibration mode (hereinafter referred to as a crystal resonator) has been frequently used as a reference source for frequency, time, etc. because it has good resonance characteristics. In recent years, social trends have led to a desire for crystal resonators that are more cost-reduced and smaller, for example, surface-mounted.

(Prior art) Figure 2 is a diagram of a crystal oscillator explaining a conventional example of type Otsu.
The same figure (11) is the same exploded view, and the same figure (b) is the same cross section □
It is a diagram.

The crystal resonator includes a crystal piece 1 enclosed in a container 4 consisting of a base 2 and a cover 3. The crystal piece 1 is formed into a rectangular shape elongated in the 7.2 axis direction, for example, as an AT cut. A pair of excitation electrodes 5 for exciting transverse vibration is formed on both sides, and extraction electrodes 6 are extended to both ends in the longitudinal direction. base 2
is made of a ceramic material in a flat plate shape, for example, a rectangular shape,
Projections 7 are integrally provided on both ends of the surface. Projection 7
An electrode layer 8 is formed on the surface of the crystal blank 1, and connection electrodes 9 are extended from both ends of the front surface to the back surface.Then, the surfaces of both end sides of the crystal blank 1 are attached to the protruding parts 7 using, for example, a conductive adhesive (not shown). The cover 3 is made of, for example, the same ceramic material as the base 2, and is sealed by being bonded to the outer periphery of the base with, for example, an epoxy adhesive. Therefore, in such a device, there is no need to attach the crystal piece 1 with a holder 10 having a clip-shaped tip as shown in the front view (main part) of FIG. 3, for example. , it is possible to reduce the number of parts and achieve miniaturization.

(Problems with the Prior Art) However, in the crystal resonator having the above configuration, the crystal blank 1 and the base 2 have different coefficients of thermal expansion. Furthermore, expansion and contraction of the base 2 due to heat, for example, directly affects the crystal piece 1 by changing the distance between the protrusions 7, since the protrusions 7 are integral with the base 2. That is, since the holder 10 and the like do not have the effect of buffering and absorbing strain, the crystal piece 1 is strained and stress is generated. As a result, there has been a problem in that electrical characteristics due to stress sensitivity characteristics and the like, particularly humidity characteristics that form a flat cubic curve near room temperature, are impaired.

(Object of the Invention) An object of the present invention is to provide a piezoelectric vibrator that is suitable for downsizing and cost reduction, improves workability, and has good electrical characteristics.

(Solution Means) The present invention provides a substrate with a second space part that is continuous with the first space part, has a depth and width smaller than the first space part, and has a divided electrode layer formed on the surface thereof, Both ends of one end of a rectangular crystal piece vibrating in a thickness-shear vibration state from which an extraction electrode is extended are fixed to the substrate surface of the first space and electrically connected to the divided electrode layer. Use it as a solution.

(Function of the Invention) In the present invention, since the main surface of one end of the rectangular crystal piece is fixed to the main surface of the base, the distortion caused by the expansion of the base does not directly act on the crystal piece, thereby affecting the thickness shear vibration. Reduce. Since the width and depth of the second space are smaller than those of the first space, the fixing position of one end of the rectangular crystal piece can be easily set. Examples will be described below.

(Embodiment) FIG. 1 is a diagram of a crystal resonator illustrating an embodiment of the present invention, in which FIG. 1(a) is an exploded view, and FIG. 1(b) is a sectional view thereof.

The crystal resonator has an AT-cut rectangular crystal piece 11 that is long in the 2' axis direction, a substrate 12, and a lid 13.
It is sealed and formed in J14.

A pair of excitation electrodes 15 (15a, 15b) for exciting vibrations is formed on both principal surfaces of the crystal piece 11. Excitation electrodes 1B (16a) are connected to one end of the excitation pair 15a, 15b in the same longitudinal direction.

16h). Then, the extraction electrode 1 on the negative side
6a is the crystal blank 11 along the longitudinal centerline a-a' via the two side surfaces that are the left side area, and the extraction electrode 16b on the other side is the right side area of the same center line. It is formed by folding back to one side via two sides. In addition,
The size of the crystal piece 11 is approximately 5 mm in the longitudinal direction and approximately 2.5 mm in the transverse direction.

The substrate 12 is made of, for example, a rectangular ceramic material as described above, and has first and second spaces 17 and 18 on the -main surface side. The first space 17 is formed approximately in the center, leaving the side walls, and the second space is formed at one end in the longitudinal direction, continuing from the first space. However, the second space 17 is different from the first space 1.
The depth, width, and length are set smaller than the depth, width, and length of 8. On the surface of the substrate in the first space 17, divided and electrically independent divided electrode layers 19a and 19b are formed, and connection electrodes 20g and 20b extend from both ends of the front surface to the back surface, respectively.

For example, one end side surface I on the other side of the crystal blank 11? l′
i is placed face-to-face with the surface of the substrate in the second space 18 and attached, for example, with a conductive adhesive (not shown). At this time, each extraction electrode 16a, 16b has a divided electrode layer 19a,
19b, respectively. Then, a cover 13 made of the same ceramic material and one piece is attached to the base 12.
The structure is such that it is bonded and sealed to the outer periphery using, for example, an epoxy adhesive.

In the crystal resonator having this configuration, only one end of the crystal piece 11 is accommodated and attached in the second space 18, so that the other end is a free end. Therefore, even if the substrate 12 expands or contracts due to thermal expansion, the distortion does not directly act on the crystal piece 11. Therefore, the stress in the crystal blank 11 caused by the difference in expansion coefficients is reduced, so that there is no need to compromise the electrical characteristics, particularly the temperature characteristics, caused by stress sensitivity characteristics and the like. And the second space part 1
8 is made smaller than each dimension of the second space 17, one end of the crystal piece 11 is inserted and positioned at the same time, and the electrical connection between the extraction electrode 16 and the divided electrode layer 19 is facilitated and workability is improved. do. Furthermore, in this embodiment, the extraction electrode 16 is formed on the back surface side via two adjacent side surfaces, thereby reducing conduction failure due to impact or the like.

(Other matters) In the above embodiment, the thickness of the crystal piece 11 is AT cut! Although the 111 configuration is used, for example, a BT cut may also be used, and in short, any thickness-sliding vibration@J configuration may be used regardless of the piezoelectric material. The length of the crystal piece 11 is about 5 mm in the longitudinal direction and about 2.5 mm in the transverse direction with respect to the Z''axis; however, it is of course possible to set the longitudinal direction to be the X axis, and the size is not limited to this. be.

In addition, if the extraction electrode ≧6
7 and folded back to the back side to reduce workability and poor conduction, but conduction can be prevented by using, for example, a conductive adhesive for fixing, so it may be done only on one side. And connection f! 1iii20 is not limited to what is shown in the drawings, and may be formed by, for example, through-ball processing, extending arbitrarily from the front side to the back side.

Further, although the purpose is to fix only one end side of the crystal piece, the other end side may be brought into contact with a support stand protruding from the substrate, for example, to increase the mounting strength.

Furthermore, although it is known that one end of a crystal piece (for example, a tuning fork type) is simply attached to the base, in the present invention, since the strain generated in the direction of the plate surface affects the thickness shear vibration, the The purpose is completely different.

(Effects of the Invention) The present invention provides a substrate with a second space that is continuous with the first space and has a small depth and width and has a split electrode W!J1 formed on the surface. A rectangular crystal piece vibrating in a thickness-shear vibration mode is provided, and both ends of one end side from which an extraction electrode is extended are fixed to the substrate surface of the first space, and electrically connected to the divided electrode layer I7. Therefore, it is possible to provide a piezoelectric vibrator that is suitable for downsizing and cost reduction, improves workability, and has good electrical characteristics.

[Brief explanation of the drawing]

Figure 1 is a diagram of a crystal oscillator for explaining the present invention.
) is an exploded view of the same, and figure (b) is a sectional view of the same. Figure 2 is a diagram of a conventional crystal oscillator; Figure 5 (,) is an exploded view of the same, Figure (b) is a cross-sectional view, and Figure 3 shows the main parts of the crystal oscillator. It is a front view. 1.11 Crystal piece, 2.12 Substrate, 3.13 Cover, 4.14 Container, 5.15 Excitation electrode pair, 6.1
6. Extraction electrode, 7. Protrusion, 8.19. Electrode layer, 9.20 Connection electrode, 13. Lid, -77. 7. First space, 18. Second space. 1st Flash 21! y

Claims (1)

[Claims] a substrate provided with a second space continuous to the first space and having a smaller depth and width than the first space; a divided electrode layer provided on the surface of the substrate forming the first space; a rectangular crystal piece that vibrates in a thickness-shear vibration state with extraction electrodes extended at both ends thereof, one end side of the rectangular crystal piece is fixed to the substrate surface of the first space, and the divided A piezoelectric vibrator characterized in that an electrode layer and the extraction electrode are electrically connected.