JPH0998023A - Surface mount piezoelectric device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure the temperature compensation by adding a temperature compensation circuit into the package of a piezoelectric device without changing the package size. SOLUTION: A single ceramic base 2 includes a wiring part 11 and an external terminal 6, and a chip thermistor (temperature compensation circuit) 5A having a capacitor function is attached between the wiring parts 112 and 113 . A piezoelectric device piece 3A is mounted on the thermistor 5A, and the terminals 41 and 42 of electrodes 4a and 4b are fixed to the terminal parts 111a and 111b of the wiring parts 111 and 112 via the conductive adhesives 81 and 82 respectively. Then the piece 3A and the temperature compensation circuit are covered with a cap and put into a package. As the thermistor 5A is used as a pillow part of the piece 3A, the temperature compensation circuit is added without increasing the package size. Furthermore, the heat of a piezoelectric device is satisfactorily transmitted to the thermistor 5A and therefore the temperature compensation is assured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a self-temperature compensating surface mount type piezoelectric device having a temperature compensating circuit built in a package of the piezoelectric device.

[0002]

2. Description of the Related Art When a piezoelectric device (crystal oscillator) is used in a temperature-compensated oscillator, it is necessary to provide a temperature compensation circuit having a thermistor and a capacitor in addition to the piezoelectric device. Normally, as shown in FIG. 8, a temperature compensation circuit B including a parallel circuit of a negative characteristic thermistor R _P and a capacitor C _P is connected in series to the crystal unit A. FIG. 9 shows frequency deviation curves a and b with respect to temperature changes before and after temperature compensation of the crystal unit. In this temperature compensation, the characteristics on the low temperature side are mainly compensated.

[0003]

As described above, it is difficult to miniaturize the oscillator because the temperature-compensated oscillator must be provided with the temperature-compensated circuit portion in addition to the piezoelectric device.

The present invention has been made in view of the above-mentioned conventional problems, and an object thereof is to provide a temperature compensation circuit in a package of a piezoelectric device without changing the size of the package. It is an object of the present invention to provide a small-sized surface-mounted piezoelectric device that can be reliably provided with temperature compensation directly.

[0005]

A surface mount piezoelectric device of the present invention comprises a thermistor having a temperature compensation compensator function, which is formed by wiring a ceramics base and serving as a pillow portion or a buffer portion of the piezoelectric device body. By mounting it, the temperature compensation part is built in the package.

Alternatively, a part of the device base plate is thinned to provide vibrating electrodes on both sides thereof as a vibrating part, and a thermistor having a temperature compensator function is provided on the remaining part of the device base plate to be packaged. It is a thing.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION

For Embodiment 1 FIG. 1, first, as shown in FIG. (A), the metallized wiring portion 11 ₁ to 11 ₃ is performed with respect to the side from the surface to the surface of the ceramic alone base 2, wiring portions 11 ₁ on the back surface
And external terminals 6 ₁ and 6 ₂ are provided so as to be connected to the external terminals 11 and _{3 3} .

Next, as shown in FIG. 1B, an alumina coating portion 7 is formed in a frame shape on the upper surface of the base 2 having the wiring portion.
In addition, the chip thermistor 5A having a capacitor function is attached to the right side of the base so as to be connected to the wiring portions 11 ₂ and 11 ₃ by using solder or a conductive adhesive.

Then, as shown in FIG. 1C, the piezoelectric device piece 3A provided with an electrode pattern for cantilever support is placed so that the chip thermistor 5A serves as a pillow portion, and the backside vibrating electrode 4a (shown in the figure). The terminal portion 4 ₁ of (omitted) is fixed to the terminal portion 11 _1a of the wiring portion 11 _{1 with} a conductive adhesive 8 ₁ , and the terminal portion 4 ₂ of the front side vibration electrode 4b is connected to the terminal portion 11 of the wiring portion 11 _2.
2a to fixedly cantilevered by the conductive adhesive _82. Finally, a box-shaped cap (not shown) is covered on this single base, and the cap and the base are joined with resin or glass to complete the package.

With the above-described structure, the external terminal 6 ₁ is connected to the vibrating electrode 4 ₁ of the piezoelectric device piece 3A,
The vibrating electrode 4 ₂ is connected to the chip thermistor 5 via the wiring portion 11 _2.
Since the other end is connected to the external terminal 6 ₂ , the piezoelectric device piece 3A is connected between the external terminals 6 ₁ and 6 _2.
A piezoelectric device having a built-in temperature compensation circuit in which the chip thermistor 5A and the chip thermistor 5A are connected in series can be obtained.

According to this embodiment, since the chip thermistor 5A is used as the pillow portion for the drop impact of the piezoelectric device piece 3A, the temperature compensating portion can be built in the package of the piezoelectric device, and the size can be reduced. Was realized. In addition, since the chip thermistor is housed in the same package as the piezoelectric device alone as a pillow portion, it is possible to detect the temperature change of the piezoelectric device more accurately. Furthermore, since the single plate base is used, the price can be kept low.

In FIG. 1, the external terminal and the wiring portion are side-surface connected, but this connection is made as through-hole connection by providing through holes 10 ₁ and 10 ₂ on the left and right sides of the base 2 as shown in FIG. Good.

Further, the metallized wiring portion 1 is formed on the single plate base 2.
If 1 _{1 to} 11 ₃ are provided in a pattern as shown in FIG. 3, it is possible to dispose the chip thermistor 5A and the piezoelectric device piece 3A in reverse, so that the left-right positional relationship of the single plate base is made uniform. Instead, a chip thermistor and a piezoelectric device piece can be mounted.

If the alumina coating portion 7 is provided on the single plate base 2 having the wiring portion in a pattern as shown in FIG. 4 (b), the coating portion 7 will be formed as shown in FIG. 4 (c). Since the cantilever support portion of the piezoelectric device piece 3A can be positioned, the positioning accuracy of the piezoelectric device piece is improved.

Embodiment 2 Referring to FIG. 5, as shown in FIG. 5A, a metallized wiring portion 11 ₁ , is formed on the front surface or the side surface of the ceramic single plate base 2.
While applying 11 ₃ , external terminals 6 ₁ and 6 ₂ are provided on the back surface so as to be connected to the wiring parts 11 ₁ and 11 ₃ .

Next, as shown in FIG. 2B, an alumina coating portion 7 is formed in a frame shape on the upper surface of the base 2 having the wiring portion, and at the same time, on the tip portion 11 _3a of the right wiring portion 11 ₃ . The chip thermistor 5B having a capacitor function having terminals on the upper and lower surfaces is attached by using solder or a conductive adhesive.

Then, as shown in FIG. 3C, the piezoelectric device piece 3B provided with the electrode pattern for supporting both ends is placed on the terminal portion 11 _1a of the wiring portion 11 ₁ and the upper surface of the chip thermistor 5B, fixed with the front side vibrating electrodes 4a terminals 4 ₁ and the rear side vibrating electrode 4b terminals 4 ₂ wiring portion terminal portions 11 _1a and the upper surface side terminal 5 ₂ in the conductive adhesive 8 ₁ and 8 ₂ of the chip thermistor 5B of the both Have and support. Finally, a box-shaped cap is placed on the single plate base and joined to the base to complete the package. The side surface connection between the external terminal and the wiring portion may be through-hole connection.

According to this embodiment, the same effect as that of the first embodiment can be obtained. Since the chip thermistor 5B also serves as a cushioning material between the ceramic single base 2 and the piezoelectric device piece 3B, it is possible to suppress the occurrence of strain stress caused by the difference in thermal expansion coefficient even in the case of supporting both ends.

[0019] For Embodiment 3 FIG. 6 embodiment, first, as shown in FIG, part 1 ₂ of the device the material plate 1 of quartz or the like by a thin plate and the vibration unit 3C by etching or the like, the right portion 1 ₃ which is not thinned A thin film thermistor 5C including a capacitor function is directly formed on the upper portion, and further, the vibrating electrode 4a and its lead terminal 4 ₁ are integrally provided on the lower surface of the vibrating portion 3C and the lower surface of the left side portion 1 ₁ of the blank plate, and the vibrating portion 3C Top and right side of the base plate 1 ₃
The lead terminal 4 ₂ of the vibrating electrode 4b and the lead terminals 5 ₁ and 5 ₂ of the thin film thermistor 5C are provided so that the vibrating electrode 4b and the thin film thermistor 5C are in series on the upper surface of the. Finally, the device blank is put into a package and completed.

The lead terminal 4 is constructed as described above.
A piezoelectric device with a built-in temperature compensation circuit in which the vibrating portion (piezoelectric device piece) 3c and the thin film thermistor 5C are connected in series between ₁ and 5 ₂ can be obtained.

According to this embodiment, since the thin film thermistor 5C is directly formed on the device base plate, the temperature compensating portion can be built in a small package, and the thin package thermistor 5C is housed in the same package. Therefore, it is possible to detect with high accuracy by the temperature change of the piezoelectric device.

Fourth Embodiment With reference to FIG. 7, first, as shown in the figure, metallized wiring portions 11 _{1 to} 11 ₃ are provided from the front surface of the ceramic single base 2 or from the front surface to the back surface. Next, a thin film thermistor 5C having a concentrator function is directly formed on the single base 2 so as to be connected to the wiring parts 11 ₂ and 11 ₃ . Then, the piezoelectric device piece 3A provided with an electrode pattern for cantilever support
A thin film thermistor (not shown) is provided as a pillow portion in the same manner as in FIG. 1, and a cap is covered to complete the package. In this case, the portions of the wiring portions 11 ₁ and 11 ₃ exposed on the lower surface of the single base 2 serve as external terminals.

According to this embodiment, since the thin film thermistor is formed on a single base, the same effect as in the third embodiment can be obtained.

[0024]

Since the present invention is configured as described above, it has the following effects.

(1) Since the cantilever-supported piezoelectric device uses a chip thermistor (including a concentrator function) as a pillow portion, it is possible to realize a small-sized device having a temperature compensating portion with a volume equivalent to that of the piezoelectric device alone.

(2) Since the double-supported piezoelectric device uses the chip thermistor as a cushioning material, it is unlikely to be affected by strain stress caused by the difference in thermal expansion coefficient between the device piece and the ceramic.

(3) Since the piezoelectric device pieces can be fixed to either side of the base, it is not necessary to specify the directionality of the base.

(4) The use of the alumina coating on the base as a stopper can improve the positioning accuracy of the piezoelectric device piece.

(5) Since the piezoelectric device piece and the temperature compensating section (chip thermistor) are housed in the same package, the temperature of the device piece can be sensed more accurately.

(6) A small device can be realized by providing the temperature compensating part and the vibrating part on one device base plate.

(7) By directly forming the thermistor on the package base, it becomes possible to provide the temperature compensating portion in the conventional package.

[Brief description of drawings]

FIG. 1 is an explanatory view of a main part structure of a cantilever type device according to a first embodiment.

FIG. 2 is an explanatory view of a base structure after metallization showing an example of connection between a wiring portion and an external terminal by a through hole.

FIG. 3 is an explanatory view of a base structure after metallization of a wiring portion when it is not necessary to specify the direction of the base.

FIG. 4 is an explanatory view of a main part structure of a device when a piezoelectric device is positioned by an alumina coating.

FIG. 5 is an explanatory view of a main part structure of a double-support type device according to a second embodiment.

FIG. 6 is an explanatory view of a main part structure of a device in which a thin film thermistor is formed on a device base plate according to the third embodiment.

FIG. 7 is an explanatory view of a main part structure of a device in which a thin film thermistor is formed on a simple substance base according to the fourth embodiment.

FIG. 8 is a temperature compensation circuit for a crystal unit.

FIG. 9 is a frequency deviation curve diagram before and after temperature compensation.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Device base plate 2 ... Ceramic simple substance base 3A, 3B ... Piezoelectric device piece 3C ... Vibrating part (piezoelectric device piece) 4 ... Vibrating electrode 5 ... Chip thermistor 6 ... External terminal 7 ... Alumina coating part 8 ... Conductive adhesive 9 ... Piezoelectric device fixing part 10 ... Through hole 11 ... Metallized wiring part

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsura Suzuki 1-31 Tsudoricho, Yonezawa City, Yamagata Prefecture Meidentsu Shin Kogyo Co., Ltd.

Claims (6)

[Claims] 1. A surface mount type piezoelectric device in which a wiring part is provided on a single body base and a cantilevered piezoelectric device piece is attached to the package, and a chip thermistor including a capacitor function for temperature compensation is provided on the pillow part of the piezoelectric device piece. A surface mount type piezoelectric device characterized in that the temperature compensation part is built into the package. 2. The piezoelectric device piece can be fixed to the opposite side of the wiring pattern of the wiring portion, regardless of whether the chip thermistor is arranged on the left or right side in the longitudinal direction of the base. The surface-mounted piezoelectric device according to 1. 3. A surface mount type piezoelectric device in which a wiring part is provided on a single body base and a cantilevered piezoelectric device piece is attached to the package, and a thin film thermistor including a capacitor function for temperature compensation is attached to the pillow part of the piezoelectric device piece. A surface mount type piezoelectric device characterized in that a temperature compensating portion is built in a package having the same size as that of a single piezoelectric device by directly forming a film on the base. 4. A surface mount type piezoelectric device in which a wiring part is provided on a single body base and a piezoelectric device piece supporting both ends is attached to the package, and a chip thermistor including a capacitor function for temperature compensation is provided in the buffer part of the piezoelectric device piece. A surface mount type piezoelectric device characterized in that the temperature compensation part is built into the package. 5. A part of the device base plate is thinned, and vibration electrodes are provided on both sides of the device base plate to form a vibrating portion, and a thermistor including a capacitor function for temperature compensation is provided in the remaining part of the device base plate, and the device is placed in a package. A surface-mounted piezoelectric device characterized in that 6. The thermistor is a thin film thermistor formed directly on a device base plate.
The surface-mounted piezoelectric device described.