JP3466492B2 - Crystal oscillator - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crystal oscillator having a crystal unit mounted on one surface of a container body.

[0002]

2. Description of the Related Art Conventionally, as a crystal oscillator which is an oscillation source of a crystal oscillator, a crystal oscillation element in which a crystal oscillator is housed in an airtight container such as a can case has been used. In this case, it was mounted on the printed wiring board together with a control element for controlling the oscillation operation of the crystal unit.

In such a structure, since the crystal oscillator in which the crystal resonator is housed in the can case is used, the crystal oscillator becomes very large.

Further, the crystal unit is used as it is, the crystal unit is mounted on the container body, and the accommodation area is hermetically used. As a typical structure, using a container having a cavity with a stepped portion, a control element is arranged on the bottom surface of the cavity portion, and a crystal oscillator is erected on the stepped portion of the cavity portion. The whole was sealed with a metal lid capable of hermetically sealing.

In such a structure, a can case is not used, and the crystal resonator and the control element are arranged in the same cavity so as to overlap each other in the thickness direction, so that the size can be reduced. However, since the control element and the crystal oscillator are arranged in the same cavity, unnecessary gas is generated from the member that joins or protects the control element, and as a result, the crystal oscillator There was a problem that the movement fluctuated.

In order to solve such a problem, as a structure, a crystal oscillator is mounted on the front surface side of a container body having a cavity portion on the bottom surface side, and a control element is mounted on the cavity portion on the bottom surface side. , A structure in which a crystal resonator on the front surface side is hermetically sealed with a metal lid is proposed (for example, Japanese Patent Laid-Open No. 10-2.
8024).

[0007]

However, in the above-mentioned structure, the circuit element including the oscillation circuit for controlling the oscillation operation of the crystal unit performs a switching operation at a high frequency and thus becomes a source of high frequency noise. .

Even if the crystal unit and the circuit element are arranged in different accommodation areas, a stray capacitance component is generated between the vibration electrode of the crystal unit and the wiring pattern of the circuit element, As a result, the stray capacitance component fluctuates the equivalent capacitance component of the crystal unit, resulting in a problem that the frequency characteristic is not stable.

The present invention has been devised in view of the above-mentioned problems, and an object thereof is to suppress generation of high frequency noise, to enable stable operation of the crystal unit, and to further improve the assembling process. It is to provide a crystal oscillator that is simplified.

[0010]

The crystal oscillator of the present invention comprises:
A casing-shaped container configured by laminating a plurality of ceramic layers and having a cavity portion on the bottom surface, a crystal resonator mounted on the surface of the container, and a crystal resonator housed in the cavity portion of the container And a circuit element for controlling the oscillating operation of the cavity, wherein a conductive film extending parallel to the ceiling surface of the cavity is provided between the ceramic layers in the container, and A ring-shaped or substantially horseshoe-shaped conductor film surrounding the wall surface in a plane is arranged, and the conductor films are connected by a via-hole conductor formed in the thickness direction of the ceramic layer. It is a thing.

Further, preferably, the crystal oscillator has a ground electrode connected to the conductor film having the ground potential, formed on the peripheral surface of the opening of the cavity of the container.

[0012]

According to the present invention, the crystal unit is mounted on the front surface side of the container. In addition, a circuit element that controls the oscillation operation is housed in the cavity portion on the bottom surface of the container. That is, since the environment in which the crystal unit is housed is independent, it is possible to effectively prevent the characteristic variation of the crystal unit with time.

Further, on the bottom surface side of the container in which the crystal unit is hermetically mounted on the surface thereof, there is formed a cavity for accommodating a circuit element for controlling the oscillation operation of the crystal unit. Therefore, even if the vibrating portion is bonded to the base substrate, it is possible to maintain the crystal oscillator having a low profile as a whole.

In particular, the oscillator circuit that performs the switch operation becomes a source of high frequency noise. However, a conductor film (shield film) having a ground potential that three-dimensionally surrounds the cavity of the container is formed. Therefore, it is possible to effectively prevent the high frequency noise from being given to the outside, and other circuits,
For example, even if a PLL element or the like is combined or combined with a transmission / reception circuit of a communication device, malfunction of other circuits will not occur.

Further, even if a stray capacitance is generated between the vibrating electrode of the crystal unit and another wiring pattern, the stray capacitance can be cut off by the conductor film of the ground potential, so that the stray capacitance is present at the vibrating electrode of the crystal unit. The component is unlikely to occur, and the equivalent capacitance component of the crystal unit does not change.

This stabilizes the vibration characteristics of the crystal unit.

In particular, in order to make the process of assembling the container very easy, a ground electrode is formed on the peripheral surface of the opening of the cavity of the container to connect with a conductor film surrounding the cavity. Therefore, when mounting on a printed wiring board, it is possible to very easily connect to a wiring pattern of earth potential.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The crystal oscillator of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is an external perspective view of a crystal oscillator of the present invention, and FIG. 2 is a sectional view thereof.

In the figure, 1 is a container, 2 is a crystal oscillator, 3 is a metallic lid, and 4 is a circuit element.

The container 1 comprises a plurality of ceramic layers 1a, 1b.
... are laminated and configured. A concave cavity portion 11 is formed on the back surface of the container 1.
On the surface of the container 1, crystal resonator connection pads 21 and 22 (22 not shown in the figure) on which the crystal resonator 2 is mounted are formed. A sealing conductor film 31 is provided around the surface. Further, a conductor film 23 having a ground potential is formed so as to surround the cavity portion 11. Here, the conductor film 23 at the ground potential means, for example, between the ceramic layers 1b and 1c, the cavity portion 11
A conductor film 23a extending in parallel with the ceiling surface of the above, a plurality of ring-shaped or substantially horseshoe-shaped conductor films 23b formed so as to planarly surround the cavity portion 11 between the ceramic layers 1c to 1e, It is composed of a horseshoe-shaped conductor film 23b and a via-hole conductor 23c connecting the ceramic layers 1c to 1d in the thickness direction.

On the peripheral surface of the opening of the cavity portion 11 (bottom surface of the container 1), the output terminal electrode of the oscillation circuit, the power supply terminal electrode 12 for supplying power and the ground terminal electrode 13 for connection with the conductor film 23 are provided. Has been formed.

On the ceiling surface of the cavity portion 11,
Various wiring patterns and electrode pads for mounting the circuit element 7 are formed, and the electrode pad 2 of the crystal unit 2 is formed.
1, 22 and various terminal electrodes 12 and the like are connected via conduction paths 14 and 15 formed inside the container 1.
In order to prevent a short circuit between the conduction paths 14 and 15 and the conductor film 23a, the conductor film 23a is provided with a penetrating region of the internal conduction paths 14 and 15 in which the conductor film is not formed.

A predetermined conductor film 23 is provided inside the container 1.
b forms a conduction path that conducts to the electrode 13 at the ground potential so that the sealing conductor film 31 and the other conductor films 23a and 23c on the surface of the container 1 have the ground potential.

In such a container 1, a plurality of predetermined conductor films including predetermined via-hole conductors are formed by using a rectangular green sheet forming the container surface side and a frame-like green sheet forming the container bottom side. The green sheets are laminated and pressure-bonded, and further integrally fired to form.

The conductor film formed on the green sheet means the electrode pads 21 and 22, the conductor film 3 for shielding.
1, a conductor film to be the conductor film 23, various terminal electrodes 12, 13
Examples thereof include a conductor film serving as the conductor and the conductor serving as the internal conduction paths 14 and 14. Such a conductor film has a through hole formed in a predetermined green sheet as needed, and the through hole is filled with a conductive paste such as silver, copper, tungsten, or molybdenum, and the above-mentioned conductive film is formed on the green sheet. It is formed by printing with a conductive paste.

[0027] Such green sheets are laminated and pressure-bonded,
The film is baked in a predetermined atmosphere, and each conductive film is plated with Ni or Au.

In such a container 1, a crystal oscillator 2 and a circuit element 4 are arranged.

The crystal unit 2 has a predetermined cut, for example, AT
It is composed of vibrating electrodes 26, 27 formed on both main surfaces of the cut rectangular quartz plate 25, and an extraction electrode portion extending from the vibrating electrodes 26, 27 to the other end.

Then, the crystal unit 2 is made of conductive adhesive material 21a, 22a via a bump member or the like that secures a gap formed on the crystal unit electrode pads 21, 22.
(22a does not appear in the figure). It should be noted that a bump member may be formed on the tip end side of the crystal unit 2 for holding the space between the crystal unit 2 and the surface of the container 1.

Crystal oscillator 2 mounted on the front side of container 1
Is hermetically sealed by the metal lid 3. The metallic lid 3 is made of a metallic material such as Kovar or 42 alloy and is welded and joined to the frame-shaped seam ring 32 that is brazed with Ag on the sealing conductor film 31 on the surface of the container 1.

Further, various circuit elements 7 constituting an oscillating circuit for controlling an oscillating operation based on a predetermined vibration of the crystal unit 2
Are housed and arranged in the cavity 11 of the container 1.

The circuit element 7 is an IC chip having at least an oscillating inverter and an amplifying inverter, a load capacitor of an oscillating circuit, a capacitor for absorbing power source noise, and for adjusting an output oscillation waveform. A resistance element or the like forming a feedback circuit of the oscillator circuit can be exemplified. Incidentally, I
The discrete chip transistor may be used instead of the C chip. In addition, it is possible to integrate resistors and some capacitors in an IC chip by the IC integration technology.

For example, an IC chip is formed on the electrode pad formed on the ceiling surface of the cavity portion 11 by surface mounting by ultrasonic fusion, flip chip bonding, or wire bonding, and capacitors and resistors are conductively bonded. It is joined through the material.

The circuit element arranged in the cavity 11 is filled and hardened with the supply resin 5 for improving the moisture resistance and the impact resistance.

In the above example, the compensation data is written in the IC chip which is the circuit element 4 in order to compensate for the temperature characteristic peculiar to the crystal unit 2, and the appropriate frequency compensation is performed according to the ambient temperature. It is an IC chip. For this reason,
As shown in, the data terminal 16 for writing the compensation data is formed on the side surface of the container 1.

According to the crystal oscillator having the above-described structure, the crystal resonator 2 and the circuit element 4 are arranged in different accommodating regions, that is, the accommodating environment in which the crystal resonator 2 is arranged is reduced. Since there is no contamination, the crystal oscillator 2 can operate stably. Also, as a whole,
The crystal unit 2 and the circuit element 4 are arranged in the thickness direction of the oscillator, and moreover, the circuit element 4 has the cavity portion 11
Since it is housed inside, a low profile can be achieved in the thickness direction of the oscillator.

Further, the circuit element 4 is arranged in the cavity portion 11 just below the crystal resonator 2. In particular, the circuit element 4 performs a switching operation. Moreover, when trying to reduce the thickness of the container 1,
A stray capacitance is generated around the vibrating electrode 27 of the crystal unit 2.

In this respect, as in the present invention, the conductor 2 of earth potential is provided inside the container 1 between the crystal resonator 2 and the circuit element 4.
3 are arranged. Therefore, it is possible to prevent the generation of stray capacitance parasitic on the vibrating electrode 27 of the crystal resonator 2 or the effective fluctuation of the stray capacitance, and the stable vibration operation of the crystal resonator 2 is possible.

Further, the conductor 23, that is, the conductor film 23a substantially parallel to the ceiling surface of the cavity 11, surrounds the inner surface of the cavity 11 so as to surround the cavity 11 three-dimensionally. The ring-shaped conductor film 23
b, the via-hole conductor 23c is formed so as to complement the gap of the ring-shaped conductor film 23b. Moreover,
The conductor 23 is formed on the peripheral surface of the cavity portion 11 (container 1
Is connected to the terminal electrode 13 of ground potential formed on the bottom surface).

As a result, in particular, the high frequency noise generated from the circuit element 4 which performs the switching operation is blocked and effectively prevented from being emitted to the outside.

Since the sealing conductor film 31 is similarly connected to the ground potential, and as a result, the metal lid 3 is also at the ground potential, the vibration electrode 26 on the upper surface side of the crystal resonator 2 is connected. The generation of parasitic stray capacitance can be reduced, and the equivalent capacitance component of the crystal unit 2 is never changed.

Further, since the oscillator is double shielded in terms of thickness, the emission of high frequency noise can be prevented more effectively.

Further, on the peripheral surface of the cavity portion 11 of the container 1 (bottom surface of the container), the terminal electrode 1 having ground potential is formed.
3, a terminal electrode 12 serving as a power supply terminal, and other than that, a terminal electrode serving as a control terminal and an oscillation output terminal are formed. Therefore, it can be easily joined to the printed wiring board by surface mounting, and the conductor film 23 and the sealing conductor film 31 can be easily and reliably set to the ground potential.

1 and 2 are examples in which the crystal unit 2 and the circuit element 4 are directly accommodated in the container 1.

[0046]

[0047]

[0048]

[0049]

[0050]

[0051]

[0052]

[0053]

[0054]

[0055]

[0056]

[0057]

[0058]

[0059]

[0060]

[0061]

[0062]

[0063]

[0064]

[0065]

[0066]

[0067]

[0068]

[0069]

[0070]

[0071]

[0072]

[0073]

[0074]

[0075]

Regarding the conductor film 23 that three-dimensionally surrounds the cavity portion 11 in FIG. 2, a matrix composed of vertical and horizontal strip conductor films that planarly spreads the flat conductor film located on the upper surface side of the cavity portion 11. It can be a pattern.

[0077]

According to the present invention, a conductor film having a ground potential that three-dimensionally surrounds the cavity portion on the bottom surface of the container is formed. Therefore, it is possible to prevent the high frequency noise from leaking to the outside from the circuit element housed in the cavity portion.

Further, the stray capacitance generated in the vibrating electrode of the crystal resonator arranged on the surface side of the container is effectively suppressed, and
The fluctuation can be completely suppressed, and stable operation becomes possible.

Further, since the crystal unit and the circuit element are arranged in different thicknesses in the thickness direction, the size and height can be reduced, and the crystal oscillator has stable characteristics.

[Brief description of drawings]

FIG. 1 is an external perspective view of a crystal oscillator according to the present invention.

FIG. 2 is a cross-sectional view of a crystal oscillator of the present invention.

[Explanation of symbols]

1 .... Container part 2 ... Crystal oscillator 3 ... Metal lid 4 ... Circuit element

Claims (2)

(57) [Claims] 1. A laminate comprising a plurality of ceramic layers,
It is composed of a casing-like container having a cavity portion on the bottom surface, a crystal oscillator mounted on the surface of the container, and a circuit element housed in the cavity portion of the container and controlling the oscillation operation of the crystal oscillator. A crystal oscillator, wherein the cavity is provided between the ceramic layers in the container .
A conductive film that extends in parallel with the ceiling surface of the tee portion and a ring-shaped or substantially surrounding the inner wall surface of the cavity portion.
Arrange a substantially horseshoe-shaped conductor film of earth potential
Together with these conductor films in the thickness direction of the ceramic layer.
A crystal oscillator characterized by being connected by a via-hole conductor formed in the . 2. The crystal oscillator according to claim 1, wherein a ground electrode connected to the conductor film having the ground potential is formed on the peripheral surface of the opening of the cavity of the container.