JPH09172325A - Surface mounted type piezoelectric oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid deterioration in an electric characteristic of a circuit element or the like or to allow deterioration in a connection state with the element to be hardly caused, to attain low profile for the oscillator, and to prevent occurrence of defective continuity and air-tightness due to a thermal distortion by separately making a part of a piezoelectric vibrator and an oscillation circuit part and connecting them electrically and mechanically through a combination in matching with a desired electric characteristic. SOLUTION: A circuit component being an integrated circuit 7 is connected to a circuit component mounted on a lead frame 5 and electrically connected by bonding wires W or the like. Part of the lead frame 5 including the circuit component is molded by a resin and a projection 61 fitted to a recessed part 4 of the piezoelectric vibrator is provided to the front side. Furthermore, electrode pads 55, 56 are exposed to the front side of the oscillation circuit formed by a resin. The piezoelectric vibrator and the oscillation circuit are connected by fitting the recessed part 4 and the projection 61 and external lead-out electrodes 24, 25 and the electrode pads 55, 56 are bonded by a conductive bonding material electrically and mechanically.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small surface mount type piezoelectric oscillator, and more particularly to a surface mount type piezoelectric oscillator in consideration of measures against thermal strain after mounting in electronic equipment and also considering reduction in height. Is.

[0002]

2. Description of the Related Art With the miniaturization of electronic equipment, a piezoelectric oscillator using a piezoelectric resonator such as a crystal resonator is required to have a low overall height and be mounted at a high density on a printed wiring board. The mounting is required to be done by an automatic machine. In order to respond to this demand, there has been a rapid movement to use a chip type in which electronic components are thin and leadless. The chip-type surface-mount type crystal oscillator 9 as shown in FIG. 7 can be made smaller in volume, including the total height, as compared with electronic parts such as a hermetically sealed crystal unit using a metal can. . In FIG. 7, a surface mount type crystal oscillator 9 is a ceramic package 92 having a crystal diaphragm mounting portion 9a and an IC chip storage portion 9b.
AT-cut quartz diaphragm 91 with excitation electrodes formed therein
Then, a circuit component 94 such as an IC (integrated circuit) chip is housed, a ceramic cap 93 is covered with these quartz diaphragms, and a sealing material such as glass is used for hermetic sealing. Electronic parts (inverters, capacitors, feedback resistors, etc.) other than the crystal diaphragm are integrated into the IC chip, and recently, in many cases, the crystal oscillation plate and the IC chip alone constitute a piezoelectric oscillation circuit. . In such a case, as shown in FIG. 7, the IC chip was housed in a package and electrically connected to the extraction electrode formed on the package with a bonding wire W.

[0003]

The above-mentioned hermetic sealing using glass has advantages such as relatively high hermeticity and less generation of harmful gas to electrodes and the like. However, the glass material has a relatively high temperature used as a bonding material, and even if a low-melting glass is used, a processing temperature and time of about 1 to 2 hours at 400 ° C. are required. On the other hand, the IC chip is often not expected to be used in such an environment, and when the high temperature treatment is performed, the electric property of the IC chip may change. Further, an alloy layer of aluminum and gold may be formed under the influence of high temperature at the connecting portion C of the gold bonding wire that is electrically connected to the aluminum electrode of the IC chip, and such an alloy layer is formed. If so, the connection portion may be mechanically fragile, which reduces the reliability of the connection. In addition, harmful gas may be generated in the electrodes of the IC chip even when sealing with resin or solder. Further, since the bending portion of the bonding wire extends in the height direction of the crystal oscillator, it is necessary to secure a certain distance between the crystal diaphragm and the IC chip or the like in order to avoid contact with the excitation electrode of the crystal diaphragm. was there. Such a configuration has been an obstacle in reducing the height.

Further, in such a chip-type piezoelectric oscillator, the external lead-out electrode 95 is formed by printing on a ceramic package, and the oscillator is mounted on a substrate of electronic equipment or the like, and soldering is performed at that portion. The stress of expansion and contraction of each component due to the fluctuation of ambient temperature and the stress at the time of dividing the substrate are directly applied to the soldering part and the ceramic package, and the conduction failure due to the cracking of the soldering part and the ceramic package itself and hermetic sealing There was a case where airtightness was poor due to cracking of the glass for automobiles.

The present invention has been made in order to solve the above-mentioned problems, and it is suitable for lowering the profile while not deteriorating the electrical characteristics of circuit elements or the like or making the connection state with elements less likely to deteriorate. Moreover, it is an object of the present invention to provide a surface mount piezoelectric oscillator in which conduction failure and airtightness failure due to thermal strain do not occur.

[0006]

According to the present invention, in a surface mount type piezoelectric oscillator, a chip type piezoelectric vibrator part and an oscillation circuit part with a lead terminal are separately manufactured to meet desired electric characteristics. With the combination described above, both are electrically and mechanically connected.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION As an embodiment of the surface mount type piezoelectric oscillator according to the present invention, the following constitution can be mentioned. As described in claim 1, a base, which is made of ceramics, is provided with necessary electrode wiring on the surface and inside and an external lead-out electrode is formed on the lower surface, and an electrode wired on the surface of the base, A chip-type piezoelectric vibrator including a piezoelectric vibrating plate on which an excitation electrode electrically and mechanically connected is formed, and a cap which covers the piezoelectric vibrating plate on the surface of the base and is hermetically sealed by a bonding material. Section, a circuit element that forms a desired oscillation circuit with this piezoelectric vibrator section, an electrode pad section that mounts this circuit element, and is electrically joined to an external lead electrode of the piezoelectric vibrator section, and an external A lead frame having an external lead-out terminal for connection with a lead frame portion, and an oscillator circuit portion having a resin-formed portion in which the lead frame portion of the circuit element portion is resin-molded. Electrode pad portion of the oscillation circuit as a conductive connection to comprising configure.

With this structure, the piezoelectric vibrator portion and the oscillation circuit portion are separated from each other, so that the heat treatment (for example, glass sealing) associated with the manufacture of the piezoelectric vibrator may affect the oscillation circuit side. Disappear. On the contrary, the piezoelectric vibrator is not affected by the release of gas from the bonding material for installing the IC. Further, since the chip-type piezoelectric vibrator is adopted, it is possible to realize a thin structure as a whole, and the external lead-out terminal formed in the oscillation circuit section can alleviate the strain with the substrate to be installed.

Further, as described in claim 2, the chip-type piezoelectric vibrator portion and the oscillation circuit portion may be provided with a concavo-convex portion which is fitted to each other. Alternatively, as shown in claim 3,
It is also possible to use an oscillation circuit section having a concave resin forming section corresponding to the outer peripheral shape of the piezoelectric vibrator section, and to store at least the lower part of the piezoelectric vibrator section in this concave resin forming section.

With this structure, the positioning relating to the connection between the chip type piezoelectric vibrator portion and the oscillation circuit portion becomes easy,
Improvement of manufacturing efficiency can be expected.

Further, as described in claim 4, a temperature compensating circuit for temperature-compensating the electric characteristics of the piezoelectric vibrator portion may be incorporated in the oscillation circuit portion so that the electric characteristics of the piezoelectric vibrator portion are compensated.

With such a configuration, it is possible to combine the oscillation circuit sections corresponding to the electrical characteristics of the piezoelectric vibrator, and it is possible to obtain an optimal combination of temperature-compensated piezoelectric oscillators.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings, taking a surface mount type crystal oscillator as an example. First Embodiment FIG. 1 is an exploded perspective view of a surface mount type crystal oscillator showing a first embodiment according to the present invention, and FIG. 2 is a view showing a state where the piezoelectric vibrator portion and the oscillation circuit portion are separated from each other in FIG. Although it is a -A sectional view, a part of external lead-out terminal is described by a dotted line. The surface mount type crystal oscillator consists of a piezoelectric vibrator part and an oscillation circuit part.
These are superposed and integrally configured.

Structure of Piezoelectric Vibrating Section The crystal vibrating plate 1 which is a piezoelectric plate is formed by forming an AT cut crystal plate in a rectangular shape, and the excitation electrodes 11 and 12 are formed in the central portions of the front and back surfaces thereof so as to cause thickness shear vibration. (The back surface is not shown) is formed. From these excitation electrodes, the extraction electrodes 11a, 1
2a (the back side is not shown) is derived. The base 2 on which the crystal vibration plate is mounted is formed by laminating ceramics, and necessary electrode wiring is provided inside the base 2, and a part of it is exposed as an electrode pad and an external lead terminal described later. Electrode pads 21, 22, 23 for mounting a crystal diaphragm are formed on the upper part of the base, and an electric signal is input to the crystal diaphragm through the electrode pads 21, 22. In addition, notches 2a and 2b are formed on the side surface of the base.
(Partly not shown) is provided, and the external lead-out electrode 2 is provided there.
4, 25 (partly not shown) are pulled out. A concave portion 4 that fits with a convex portion 61 of an oscillation circuit portion, which will be described later, is provided in the central portion of the bottom surface of the base in the plate thickness direction. The cap 3 is made of ceramics and has a reverse recess 31 that secures a vibration space. The cap 3 is hermetically bonded to the base with a low melting point glass G.

Structure of Oscillation Circuit Section The oscillation circuit section comprises a lead frame 5 as a whole, at least one circuit element 7 mounted on the lead frame, and a resin 6 covering these circuit element parts. The lead frame 5 includes four external lead-out terminals 51, 52, 53, 54 connected to the outside, electrode pads 55, 56 exposed on the surface of the above-mentioned resin, and a circuit element installation portion 5.
7 and each external lead terminal is bent and formed so as to have a function of buffering a strain generated between the external lead terminal and the mounted substrate. When the piezoelectric vibrating portions are superposed on the electrode pads 55 and 56, the external lead electrodes 24 and 25 described above are respectively formed.
It is designed to correspond with the one. The circuit element installed on the circuit element mounting portion of the lead frame is an integrated circuit (I
C) 7 and necessary electrical connection is made by a bonding wire W or the like. This circuit element may employ a plurality of elements as necessary. A part of the lead frame including this circuit element is resin-molded, and a convex portion 61 that fits into the concave portion of the piezoelectric vibrator portion is provided on the surface. The electrode pads 55 and 56 are exposed on the surface of the oscillator circuit portion formed of resin.

The piezoelectric vibrator portion and the oscillating circuit portion are joined by fitting the above-mentioned concave portion and convex portion,
Moreover, the external lead-out electrodes 24 and 25 and the electrode pads 55 and 56 are electromechanically bonded to each other with a conductive bonding material. With such a configuration, the piezoelectric vibrator portion and the oscillation circuit portion are separated from each other, so that the influence of heat treatment (for example, glass sealing) for manufacturing the piezoelectric vibrator is not exerted on the oscillation circuit side. On the contrary, the piezoelectric vibrator is not affected by the release of gas from the bonding material for IC installation. Furthermore, because a chip-type piezoelectric vibrator is used,
A thin structure can be realized as a whole, and the external connection lead formed in the oscillation circuit section can alleviate distortion with the substrate to be installed. In the above description,
Although the ceramic material has been described as an example of the package material of the piezoelectric vibrator portion, an insulating material such as a resin material may be used. In addition, the package may be configured such that the base has a concave shape as a whole, a circumferential metal ring is formed in the opening, and a metal cap is used for welding.

Second Embodiment FIG. 3 is a side view in the short side direction showing a second embodiment according to the present invention. Since the configuration is almost the same as that of the first embodiment, some description will be omitted and the same numbers will be used for description. The same applies to the following examples. The electrode pads 57 and 58 of the oscillation circuit section may be extended and formed. This makes it possible to measure the electrical characteristics of the piezoelectric vibrator unit itself even after the piezoelectric vibrator unit and the oscillation circuit unit are assembled, and facilitate investigation when a failure occurs. In addition, since the electrode pad is extended, the application state of the conductive bonding material S can be clearly confirmed.

Third Embodiment FIG. 4 is a side view showing a third embodiment according to the present invention.
The piezoelectric vibrating portion is provided with two or more concave portions 41 and 42, and the oscillation circuit portion is also provided with two or more convex portions 62.63, and these are joined to join them.
Since it is fixed by positioning at multiple points, it is expected to improve the positional accuracy when joining.

Fourth Embodiment FIGS. 5 and 6 are side views showing two fourth embodiments according to the present invention. In the embodiment shown in FIG. 5, a concave portion 64 corresponding to the outer peripheral shape of the piezoelectric vibrator portion is formed on the surface of the oscillation circuit portion by resin formation, and an electrode pad is provided in this concave portion, and the piezoelectric vibrator is formed. It is electrically connected to the part.
Further, the embodiment shown in FIG. 6 has a configuration in which a concave portion 65 is provided in the lower portion of the oscillation circuit portion, and the piezoelectric vibrator portion is inserted and installed in this portion from below. Moreover, the external lead-out terminal of the lead frame is led out from the upper side surface of the oscillation circuit section, and the circuit element 7 is also placed beside the piezoelectric vibrator section. Each of the embodiments has an advantage that the piezoelectric vibrator part can be easily installed. In particular, when a thin piezoelectric vibrator is used, the distance between the external lead-out terminal and the substrate to be mounted may become too small, and the external lead-out terminal may not provide a sufficient cushioning effect. If
A sufficient cushioning effect can be obtained with the configuration shown in FIG.

Fifth Embodiment In each of the above configurations, a temperature compensation circuit for temperature-compensating the electric characteristics of the piezoelectric vibrator section may be incorporated in the oscillation circuit section to compensate the electric characteristics of the piezoelectric vibrator section. . For example, an AT-cut crystal unit exhibits a frequency-temperature characteristic represented by a cubic curve near the normal operating temperature,
It also shows the frequency-temperature characteristic represented by the following approximate curve.
For such a crystal unit having frequency-temperature characteristics that can be distinguished into multiple types, prepare a combination of temperature compensation circuit elements that appropriately temperature-compensates the crystal unit according to the characteristics of the crystal unit. By providing the oscillation circuit section, a practical temperature compensation type piezoelectric oscillator can be obtained. As the temperature compensating circuit element, there are a thermistor, a capacitor, a resistor and the like, and the circuit configuration and constants may be selected in accordance with the characteristics of the piezoelectric vibrator section.

[0021]

According to the present invention, since the piezoelectric vibrator portion and the oscillation circuit portion are separated from each other, heat treatment (for example, glass sealing) for manufacturing the piezoelectric vibrator exerts an influence on the oscillation circuit side. Will disappear. On the contrary, the piezoelectric vibrator is not affected by the release of gas from the bonding material for IC installation. Furthermore, since a chip-type piezoelectric vibrator is adopted, a thin shape can be realized as a whole, and the external connection leads formed in the oscillation circuit section alleviate the strain with the substrate to be installed, resulting in poor conduction due to thermal strain. It is possible to prevent the occurrence of airtightness. Therefore, the reliability of the surface mount piezoelectric oscillator can be improved.

Further, as described in claims 2 and 3, the chip-type piezoelectric vibrator portion and the oscillation circuit portion are fitted to each other, whereby the positioning relating to the connection between the chip-type piezoelectric vibrator portion and the oscillation circuit portion can be easily performed. Therefore, improvement in manufacturing efficiency can be expected.

Further, as described in claim 4, a temperature compensating circuit for temperature-compensating the electric characteristic of the piezoelectric vibrator portion is incorporated in the oscillation circuit portion, and the electric characteristic of the piezoelectric vibrator portion is compensated. It is possible to combine the oscillation circuit units corresponding to the electrical characteristics of the piezoelectric vibrator, and to obtain the temperature-compensated piezoelectric oscillator in a practical combination.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a first embodiment of a surface mount piezoelectric oscillator according to the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a diagram showing a second embodiment.

FIG. 4 is a diagram showing a third embodiment.

FIG. 5 is a diagram showing a fourth embodiment.

FIG. 6 is a diagram showing a fourth embodiment.

FIG. 7 is a diagram showing a conventional example.

[Explanation of symbols]

 1,81 Piezoelectric vibration plate (crystal vibration plate) 2,9 Base 3,91 Cap 4,41,42,64,65 Recess 5 Lead frame 6 Resin 61,62,63 Convex 7 Circuit element

Claims (4)

[Claims] 1. A base made of an insulating plate, which is provided with necessary electrode wiring on the surface and inside and an external lead-out electrode is formed on the lower surface, and an electrode wired on the surface of the base, electrically and mechanically. A piezoelectric vibrating plate having an excitation electrode connected thereto,
A chip-type piezoelectric vibrator part that covers the piezoelectric vibrating plate on the surface of the base and has a cap that is hermetically sealed by a bonding material; and a circuit element that constitutes this piezoelectric vibrator part and a desired oscillation circuit. A lead frame having the circuit element mounted thereon, the electrode pad section being electrically joined to the external lead-out electrode of the piezoelectric vibrator section, and the external lead-out terminal for connecting to the outside; and the circuit element section. Of the surface mount type piezoelectric device, in which the lead frame portion of the oscillator circuit part is provided with a resin forming part resin-molded, and the external lead-out electrode of the piezoelectric vibrator part and the electrode pad part of the oscillator circuit part are conductively connected. Oscillator. 2. The surface-mounted piezoelectric oscillator according to claim 1, wherein the piezoelectric vibrator portion and the oscillation circuit portion are provided with concave and convex portions which are fitted to each other. 3. An oscillation circuit section having a concave resin forming portion corresponding to the outer peripheral shape of the piezoelectric vibrator portion is used, and at least the lower portion of the piezoelectric vibrator portion is housed in the concave resin forming portion. The surface-mounted piezoelectric oscillator according to claim 1, which is characterized in that. 4. The surface mounting according to claim 1, 2 or 3, wherein a temperature compensating circuit for temperature-compensating the electric characteristics of the piezoelectric vibrator portion is incorporated in the oscillation circuit portion to compensate the electric characteristics of the piezoelectric vibrator portion. Type piezoelectric oscillator.