JPH08107313A - Surface mount piezoelectric oscillator and its manufacture - Google Patents

Abstract

PURPOSE: To provide a surface mount piezoelectric oscillator and its manufacture method suitable for a low height and with less manufacture dispersion in which the electric characteristic of circuit components or the like is not deteriorated or the connecting state to the components is hardly deteriorated. CONSTITUTION: A required electrode wiring is made inside a substrate 2 on which a crystal vibration plate with exciting electrodes is mounted, and part of the wiring is exposed as an electrode pad. A recessed part 24 is provided on the bottom side of the substrate 2 and a recessed part 25 for mounting an IC chip whose depth is deeper than that of the part 24 is provided at the middle. The IC chip 4 is contained in the recessed part 25, connected to electrode pads 24a-24d of the substrate 2 through the bonding wire, a resin member is filled in the recessed part 25 and the IC chip or the like is embedded. Furthermore, the cap has an inverted recessed part to secure a vibration space and the outer circumferential size is smaller than the outer circumferential size of the substrate 2 and then a flange 20 is formed on the substrate 2.

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, considering a reduction in height, taking measures against heat at the time of manufacture, and a surface mount type piezoelectric oscillator with less manufacturing variation, and a surface mount type piezoelectric oscillator. The present invention relates to a method of manufacturing a mounted piezoelectric oscillator.

[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. 8 can be made smaller in volume including the total height as compared with electronic parts such as a hermetically sealed crystal resonator using a metal can. . In FIG. 8, the surface mount 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
And a circuit component 94 such as an IC chip is housed,
The ceramic cap 93 is covered with these crystal diaphragms, etc., and hermetically sealed with a sealing material such as glass. IC
Electronic components (inverter,
Capacitors, feedback resistors, etc.) are integrated into an IC, and recently, a piezoelectric oscillation circuit is often composed of only a crystal diaphragm and an IC chip. In such a case, the IC chip was housed in a package as shown in FIG. 8 and electrically connected to the extraction electrode formed on the package by 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.

In order to solve such a problem, the same applicant previously proposed the surface mount type piezoelectric oscillator 8 as shown in FIG.
Suggested. That is, the piezoelectric vibrating plate 81 is attached to the cap 83.
The surface mount piezoelectric device is hermetically sealed on the upper portion of the base 82, and other circuit components 84 such as ICs are housed in a recess provided on the lower surface of the base and embedded by filling with a resin material 85. It is an oscillator. The surface-mounted piezoelectric oscillator with such a configuration is
The chamber of the piezoelectric diaphragm and the chamber of the circuit element such as an IC are spatially separated, so that the piezoelectric diaphragm can be hermetically sealed and other circuit parts can be mounted separately. Therefore, it is possible to obtain a surface-mounted piezoelectric oscillator that does not deteriorate the electrical characteristics of the circuit element or the like or makes it difficult to deteriorate the connection state with the element and that is suitable for reducing the height.

In the production of such a surface-mounted piezoelectric oscillator, a circuit element forming an oscillation circuit is housed in a recess of a base and a necessary electrical connection is made. Usually, as shown in FIG. The recesses are installed on the tape T so that the recesses face upward, and the production of these is advanced. However, the thickness of the bonding material at the time of bonding may differ due to the difference in the amount and viscosity of the bonding material S such as glass that bonds the base 82 and the cap 83. In such a case, the height of the circuit component mounting portion on the back surface of the base may be different as indicated by the height difference h in FIG. 6, and in manufacturing using an automatic machine or the like,
This sometimes caused manufacturing defects such as defective connection of wire bonding.

The present invention has been made 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-mounted piezoelectric oscillator with less manufacturing variation and a method for manufacturing the surface-mounted piezoelectric oscillator.

[0007]

A surface mount type piezoelectric oscillator according to the present invention is made of ceramics, is provided with a necessary electrode wiring, and has a base having a recess in at least a lower surface in a thickness direction, and an upper portion of the base. A piezoelectric vibrating plate on which an excitation electrode is formed that is electrically and mechanically connected to the base plate, a cap that covers the piezoelectric vibrating plate above the base and is hermetically sealed by a bonding material, and a recess in the base. In a surface-mounted piezoelectric oscillator consisting of a circuit element that constitutes an oscillation circuit that is housed and required electrical connection, and an insulating resin material filled in the recess, in the peripheral dimension of the base rather than the outer dimension of the cap Is increased to provide a flange portion on the outer peripheral portion of the base. Further, notches may be provided at a plurality of positions on the upper surface of the outer circumference of the base or over the entire circumference.

Further, the method of manufacturing such a surface mount type piezoelectric oscillator is prepared by providing a base which is made of ceramics and which is provided with necessary electrode wiring and at least a recess is formed in the lower surface in the thickness direction. The step of electrically and mechanically connecting the piezoelectric vibrating plate on which the excitation electrode is formed, and the cap is airtightly bonded to the upper part of the base by a bonding material to hermetically seal the piezoelectric vibrating plate and the like. In the step of stopping and the carrier tape having a plurality of through holes corresponding to the outer peripheral shape of the cap, the cap is installed in the through holes so that the lower surface of the base is directed upward, and the base portion is formed by the flange portion or notch. A step of supporting the table, a step of thereafter storing a circuit element forming an oscillation circuit in a recess on the lower surface of the base and making necessary electrical connections, and an insulating step in the recess storing the circuit element. Characterized by comprising a resin material and a step of filling.

[0009]

The piezoelectric vibrating plate is hermetically sealed on the upper part of the base with a cap, and other circuit components such as ICs are housed in the recesses provided on the lower surface of the base and are filled with a resin material. Thus, the chambers in which they are placed are spatially separated. With such a configuration, the piezoelectric vibration plate can be hermetically sealed and other circuit components can be separately mounted. Therefore, for example, a glass material that requires a relatively high temperature before the circuit components such as ICs are mounted. Can be used as a bonding material to hermetically seal the piezoelectric diaphragm. Since the circuit components such as the IC are mounted later, there is no problem of changes in the electrical characteristics of the IC or the like and deterioration of the connection portion. Moreover, after examining the electrical characteristics of the hermetically sealed piezoelectric vibrating plate portion, a circuit component such as an IC can be mounted. If the examined electrical characteristics do not satisfy the predetermined standard level, it is possible to prevent the occurrence of defective products by not mounting ICs or other circuit components. Further, in the surface mount piezoelectric oscillator having such a structure, since the flange portion is formed, the flange portion is locked around the through hole formed in the carrier tape to mount the circuit component on the back surface of the base. Etc., and because the cap is not supported by the carrier tape,
Even when the thickness of the bonding material when bonding is different due to the difference in the amount and viscosity of the bonding material between the cap and the base, the height of the circuit component mounting portion on the back surface of the base does not differ.

Further, according to the invention of claim 2, since the notch is provided at a plurality of positions or the entire circumference of the outer peripheral upper surface of the base, the notch is formed in the through hole formed in the carrier tape. It is easy to mount the circuit parts on the back surface of the base, etc., and the excess glass material for joining the base and the cap does not easily flow into this notch.

According to the invention of claim 3, the step of electrically and mechanically connecting the piezoelectric vibrating plate to the upper part of the base, and the cap being joined to the upper part of the base with a glass material, After the process of hermetically sealing the piezoelectric diaphragm, etc., the circuit elements that make up the oscillation circuit are stored in the recesses of the base, the necessary electrical connections are made, and the embedding process is performed with a resin material, so high temperature It is not affected by heat at the time of hermetically sealing the glass material that needs to be treated. Further, a carrier tape having a plurality of through holes corresponding to the outer peripheral shape of the cap, the cap is penetrated and installed so that the lower surface of the base is directed upward,
By supporting this base with the flange portion or notch, it becomes easy to mount circuit components on the back surface of the base, and since the cap is not supported by the carrier tape, the bonding material between the cap and the base The height of the circuit component mounting portion on the rear surface of the base does not differ even when the thickness of the joining material when joining is different due to factors such as the amount and viscosity of the joining material.

[0012]

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 internal sectional view of a surface mount type crystal oscillator showing a first embodiment according to the present invention, and FIG. 2 is a state in which the surface mount type crystal oscillator having the configuration of FIG. 1 is mounted on a carrier tape. FIG. 3 is a perspective view showing the state of FIG. 3, and FIG. 3 is a sectional view showing a state where the carrier tape of FIG. 2 is mounted. The quartz crystal vibrating plate 1 which is a piezoelectric plate is formed by forming an AT-cut quartz crystal plate in a rectangular shape, and excitation electrodes (not shown) are formed in the central portions of the front and back surfaces thereof so as to perform thickness shear vibration. From these excitation electrodes, a lead electrode (not shown) is led out to one end in the longitudinal direction of the crystal diaphragm 1. The base 2 on which the crystal diaphragm 1 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 described later. Electrode pads 21 and 22 for mounting the crystal diaphragm 1 are formed on the upper part of the base, and electric signals are input to the crystal diaphragm 1 through the electrode pads 21 and 22. Further, electrode lead-out portions 2a, 2b, 2c, 2d, which are partially cut away, are provided on the side surface of the base, and external lead-out electrodes are led out there. A recess 24 in the plate thickness direction is provided on the bottom surface of the base so that the electrode pads 24a, 24b,
A concave portion 24 in which 24c and 24d are formed, and the concave portion 24
A deeper recess 25 for mounting an IC chip is provided in the central portion of. The IC chip 4 is housed in the recess 25, and the electrode pad of the IC chip 4 and the electrode pad 24 are
After connecting a, 24b, 24c, and 24d with the bonding wire W, the resin material 5 is filled in these recesses,
The IC chip or the like is embedded. The cap is made of ceramics and has a reverse recess 31 for ensuring a vibration space. The outer peripheral dimension of the cap is set to be smaller than the outer peripheral dimension of the base, so that the outer peripheral portion of the base has a flange portion. 20 are formed.

In order to manufacture this surface mount type crystal oscillator, the crystal vibrating plate 1 on which the excitation electrodes are formed is mounted on the electrode pads 21 and 22 provided on the base, and conductive bonding (using a conductive bonding material) is performed. (Not shown), a low-melting glass G is arranged near the outer periphery of the upper part of the base, and the cap 3 is placed on the low-melting glass G so that its end portion is positioned, and nitrogen gas is added. Melt bonding is performed by heating at 400 ° C. for about 2 hours in the atmosphere. As a result, the crystal diaphragm is hermetically sealed by the cap 3 on the upper part of the base. To mount a circuit element such as an IC chip in the recess 25 on the lower surface of the base, the base is turned over so that the lower surface faces upward and mounted on the carrier tape T. The carrier tape T is formed with a plurality of through holes T1 and T2 corresponding to the outer peripheral shape of the cap. The cap is penetrated through the carrier tape T so that the lower surface of the base faces upward, and the flange is formed. The part 20 supports this base. Then, an IC chip is placed in the recess 25 on the lower surface of the base, and the electrode pads of the IC chip and the electrode pads 24a, 24b, 24c, 24d are electrically connected by the bonding wires W. Then, the insulating resin material 5 made of epoxy resin is filled in the recesses 24 and 25 to embed an IC chip or the like.

Second Embodiment FIG. 4 is a perspective view showing a second embodiment of the present invention.
FIG. 5 is a partial perspective view of a carrier tape used in manufacturing the surface-mounted piezoelectric oscillator of FIG. The description of the same components as those of the first embodiment will be partially omitted and the same numbers will be used for the description. The flange portion 60 of the base 6 is provided with elongated notches 61, 62, 63, 64 (64 is not shown) on four sides. A plurality of through holes T3, T4 are formed in the carrier tape T, and supporting portions 71, 72, 73, 74 corresponding to the notches 61, 62, 63, 64 of the base are formed in these through holes, respectively. It is protruding.
To mount a circuit element such as an IC chip in the concave portion 65 on the lower surface of the base, turn over the lower surface of the base so that the notches 61, 62, 63, 64 are formed on the carrier tape T.
The support parts 71, 72, 73, 74 are fixed to the carrier tape. Then, an IC chip is placed in the recess 65 on the lower surface of the base, and the electrode pads of the IC chip and the electrode pads are electrically connected by a bonding wire. 2e ... 2e are external lead-out electrodes that lead out electrodes of the piezoelectric vibrating plate or electrodes such as IC chips to the outside.

According to this embodiment, since the notches are provided at a plurality of positions on the upper surface of the outer periphery of the base, the notches are locked around the through holes formed in the carrier tape to form the base. In addition to facilitating the mounting of circuit components on the back surface of the base, it is difficult for excess glass material for joining the base and the cap to flow into the notch. Therefore, the excess of the bonding material does not adhere to the base portion supported by the carrier tape, and stable manufacturing can be performed. The notch may be provided at a plurality of positions on the upper surface of the outer periphery of the base as described above, or may be provided over the entire circumference.

The present invention is not limited to the above embodiment, but can be applied to the case of an oscillator having another complicated circuit configuration (for example, a temperature compensation type crystal oscillator). Further, the resin material used may be not only an epoxy resin but also a silicone resin or a urethane resin. Further, it is possible to make a device such as providing a groove on the flange portion of the base to prevent the joining material for joining the base and the cap from flowing out.

[0017]

According to the present invention, the piezoelectric vibrating plate is hermetically sealed on the upper portion of the base by the cap, and other circuit components such as ICs are housed in the recesses provided on the lower surface of the base, and the resin The chambers in which they are arranged are spatially separated by the structure in which they are buried by filling the material. With such a configuration, the piezoelectric vibration plate can be hermetically sealed and other circuit components can be separately mounted. Therefore, for example, a glass material that requires a relatively high temperature before the circuit components such as ICs are mounted. Can be used as a bonding material to hermetically seal the piezoelectric diaphragm. Since the mounting of circuit components such as IC will be performed later, changes in the electrical characteristics of IC,
The problem of deterioration of the connection part disappears. Further, after examining the electrical characteristics of the hermetically sealed piezoelectric vibrating plate portion, a circuit component such as an IC can be mounted. If the examined electrical characteristics do not satisfy the predetermined standard level, it is possible to prevent the occurrence of defective products by not mounting ICs or other circuit components. Further, in the surface mount piezoelectric oscillator having such a structure, since the flange portion is formed, the flange portion is locked around the through hole formed in the carrier tape to mount the circuit component on the back surface of the base. Etc., and because the cap is not supported by the carrier tape, even if the thickness of the bonding material when bonding is different due to the difference in the amount and viscosity of the bonding material between the cap and the base, The height of the circuit component mounting portion on the back surface of the base does not differ. Therefore, it is possible to obtain a highly reliable surface mount piezoelectric oscillator with less manufacturing variation.

Further, according to the invention of claim 2, since the notch is provided at a plurality of positions or the entire circumference of the upper surface of the outer periphery of the base, the notch portion is a through hole formed in the carrier tape. It makes it easy to mount the circuit parts on the back of the base, etc. Therefore, it is possible to obtain a highly reliable surface mount piezoelectric oscillator with less manufacturing variation. In addition, excess glass material that joins the base and the cap does not easily flow into this cutout portion, and excess adhesive does not adhere to the base portion supported by the carrier tape, ensuring stable manufacturing. You can

According to the third aspect of the invention, the step of electrically and mechanically connecting the piezoelectric vibrating plate to the upper part of the base, and the cap being joined to the upper part of the base with a glass material, After the process of hermetically sealing the piezoelectric diaphragm, etc., the circuit elements that make up the oscillation circuit are stored in the recesses of the base, the necessary electrical connections are made, and the embedding process is performed with a resin material, so high temperature It is not affected by heat at the time of hermetically sealing the glass material that needs to be treated. Further, a carrier tape having a plurality of through holes corresponding to the outer peripheral shape of the cap, the cap is penetrated and installed so that the lower surface of the base is directed upward,
By supporting this base with the flange portion or notch, it becomes easy to mount circuit components on the back surface of the base, and since the cap is not supported by the carrier tape, the bonding material between the cap and the base The height of the circuit component mounting portion on the rear surface of the base does not differ even when the thickness of the joining material when joining is different due to factors such as the amount and viscosity of the joining material. Therefore, it is possible to obtain a highly reliable method of manufacturing a surface-mounted piezoelectric oscillator with less manufacturing variation.

[Brief description of drawings]

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

FIG. 2 is a perspective view showing a state in which the surface mount crystal oscillator having the configuration of FIG. 1 is mounted on a carrier tape.

FIG. 3 is a cross-sectional view showing a state where the carrier tape of FIG. 2 is mounted.

FIG. 4 is a perspective view showing a second embodiment.

5 is a perspective view showing a state in which the surface mount crystal oscillator having the configuration of FIG. 4 is mounted on a carrier tape.

FIG. 6 is a diagram showing a conventional example.

FIG. 7 is a diagram showing a conventional example.

FIG. 8 is a diagram showing a conventional example.

[Explanation of symbols]

 1,81 Piezoelectric vibration plate (quartz vibration plate) 2,9 Base 24,25,71,72,73 Recessed portion 3,91 Cap 4,82 IC chip 5 Resin material

Claims (3)

[Claims] 1. A base, which is made of ceramics, is provided with necessary electrode wiring, and at least a lower surface is provided with a recess in the thickness direction, and an excitation electrode electrically and mechanically connected is formed on the base. A piezoelectric vibrating plate, a cap that covers the piezoelectric vibrating plate above the base and is hermetically sealed by a bonding material, and an oscillation circuit that is housed in the recess of the base and is electrically connected as necessary In the surface mount type piezoelectric oscillator consisting of the circuit element and the insulating resin material filled in the recess, by making the outer peripheral dimension of the base larger than the outer peripheral dimension of the cap, the flange portion is formed on the outer peripheral portion of the base. A surface-mounted piezoelectric oscillator, comprising: 2. A surface mount type piezoelectric oscillator, wherein notches are provided at a plurality of positions or the entire circumference of the upper surface of the outer periphery of the base. 3. A method for manufacturing the surface-mounted piezoelectric oscillator according to claim 1, wherein the substrate is made of ceramics, is provided with necessary electrode wiring, and has a recess formed in at least the lower surface in the thickness direction. A step of preparing a pedestal and electrically and mechanically connecting a piezoelectric vibrating plate on which an excitation electrode is formed on the base, and a cap is airtightly joined to the top of the pedestal by a bonding material A step of hermetically sealing a diaphragm or the like, and a carrier tape having a plurality of through holes corresponding to the outer peripheral shape of the cap, the cap is installed in the through holes so that the lower surface of the base is directed upward, A step of supporting this base with a flange portion or a notch, a step of storing circuit elements that constitute an oscillation circuit in a recess on the bottom surface of the base and making necessary electrical connections, and a step of storing the circuit elements. did A method of manufacturing a surface-mounted piezoelectric oscillator, comprising the step of filling the recess with an insulating resin material.