JP2000138533A - Quartz oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a quartz oscillator which can be reduced in size and height and can suppress the occurrence of high-frequency noise and the quartz resonator of which can operate stably. SOLUTION: A crystal oscillator is constituted in such a way that a crystal resonator 2 is arranged on the surface of an enclosure-like container having a cavity section 11 on its bottom face and the top side of the container 1 is airtightly sealed with a metallic cap 3 so as to cover the resonator. Then a circuit element 4 which controls oscillating operations is housed in the cavity section 11. In addition, conductor films 23 (23a-23c) having earth potentials are formed in the container 1 so that the films 23 may three-dimensionally surround the cavity section 11.

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 resonator mounted on one surface of a container.

[0002]

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

[0003] In such a structure, a crystal oscillator having a crystal oscillator housed in a can case is used, so that the crystal oscillator becomes very large.

Further, the quartz oscillator is used as it is, the quartz oscillator is mounted on a container body, and the housing area is used in an airtight manner. As a typical structure, using a container having a cavity in which a step is formed, a control element is arranged on the bottom surface of the cavity, a crystal resonator is erected on the step of the cavity, and a cavity is formed. The whole was sealed with a metal lid that can be hermetically sealed.

[0005] In such a structure, since the quartz resonator and the control element are arranged in the same cavity so as to overlap in the thickness direction without using a can case, the size can be reduced. However, since the control element and the crystal resonator are arranged in the same cavity, unnecessary gas is generated from members that join and protect the control element, and as a result, the crystal resonator There is a problem that the operation fluctuates.

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

[0007]

However, in the above-described 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. .

Further, even if the crystal unit and the circuit element are arranged in different housing areas, a floating capacitance component is generated between the vibrating electrode of the crystal unit and the wiring pattern of the circuit element. As a result, there is a problem that the stray capacitance component fluctuates the equivalent capacitance component of the crystal resonator, and the frequency characteristics are not stable.

The present invention has been devised in view of the above-mentioned problems, and has as its object to suppress the generation of high-frequency noise, to enable stable operation of a crystal unit, and to make assembly processing extremely difficult. Another object of the present invention is to provide a crystal oscillator which is simplified.

[0010]

SUMMARY OF THE INVENTION The present invention provides a housing-like container having a cavity on the bottom surface, a crystal oscillator mounted on the surface of the container, and a crystal oscillator housed in the cavity of the container. And a circuit element for controlling the oscillating operation of (1), wherein a conductive film having a ground potential surrounding the cavity in a three-dimensional manner is formed in the container.

Preferably, the crystal oscillator has an earth electrode connected to the conductor film having the earth potential formed on the peripheral surface of the opening of the cavity of the container.

[0012]

According to the present invention, the quartz oscillator is mounted on the front side of the container. Further, a circuit element for controlling the oscillating operation is accommodated in the cavity on the bottom surface of the container. That is, since the accommodation environment of the crystal unit is independent, it is possible to effectively prevent the characteristic fluctuation of the crystal unit over time.

On the bottom side of the container on which the crystal unit is mounted airtight, a cavity is formed which can accommodate a circuit element for controlling the oscillation operation of the crystal unit. For this reason, even if the vibrating portion is bonded to the base substrate, a crystal oscillator having a reduced height can be maintained as a whole.

In particular, an oscillation circuit that performs a switching operation becomes a source of high-frequency noise. However, a conductor film (shield film) having a ground potential and three-dimensionally surrounding the cavity of the container is formed. For this reason, it is possible to effectively prevent high frequency noise from being applied 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 does 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 having the ground potential. The equivalent capacitance component of the crystal unit does not change because the component hardly occurs.

As a result, the oscillation characteristics of the crystal unit are stabilized.

Particularly, in order to make the assembling process of the container very easy, an earth electrode connected to the conductor film surrounding the cavity is formed around the opening of the cavity of the container. Therefore, when mounting on a printed wiring board, it can be very easily connected to the wiring pattern of the ground potential.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a crystal oscillator according to the present invention will be described in detail with reference to the drawings.

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

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

The container 1 has a plurality of ceramic layers 1a and 1b.
Are laminated. A concave cavity 11 is formed on the back surface of the container 1.
On the surface of the container 1, connection pads 21 and 22 for the crystal resonator on which the crystal resonator 2 is mounted (22 is not shown in the drawing) are formed. A sealing conductor film 31 is provided around the surface. A conductor film 23 having a ground potential is formed so as to surround the cavity 11. Here, the conductor film 23 at the ground potential is, for example, between the ceramic layers 1b and 1c and the cavity 11
And a plurality of ring-shaped or roughly horseshoe-shaped conductor films 23b formed so as to planarly surround the cavity portion 11 between the ceramic layers 1c to 1e. And a via-hole conductor 23c that connects the horseshoe-shaped conductor film 23b in the thickness direction of the ceramic layers 1c to 1d.

The output terminal electrode of the oscillation circuit, the power supply terminal electrode 12 for supplying power, and the ground terminal electrode 13 connected to the conductor film 23 are provided on the peripheral surface of the opening of the cavity 11 (the bottom surface of the container 1). Is formed.

On the ceiling surface of the cavity 11,
Various wiring patterns and electrode pads for mounting the circuit element 7 are formed.
1, 22 and various terminal electrodes 12 are connected via conduction paths 14 and 15 formed inside the container 1.
In order to prevent a short circuit between the conductive paths 14 and 15 and the conductive film 23a, a through region of the internal conductive paths 14 and 15 where no conductive film is formed is formed in the conductive film 23a.

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

Such a container 1 has a plurality of rectangular green sheets forming the container front side and a frame-shaped green sheet forming the container bottom side, on which a predetermined conductor film including a predetermined via-hole conductor is formed. The green sheets are laminated and pressed, and are further integrally baked.

The conductive film formed on the green sheet includes the electrode pads 21 and 22 and the conductive film 3 for shielding.
1. Conductive film serving as conductive film 23, various terminal electrodes 12, 13
Conductor film to be used, conductors to be used as the internal conduction paths 14, and the like. Such a conductive film forms a through hole as necessary in a predetermined green sheet, fills the through hole with a conductive paste such as silver, copper, tungsten, or molybdenum, and forms the above conductive film on the green sheet. It is formed by printing with a conductive paste.

Such green sheets are laminated and pressed,
Baking is performed in a predetermined atmosphere, and Ni plating or Au plating is applied on each conductive film.

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

The crystal oscillator 2 is provided with a predetermined cut, for example, AT
Vibration electrodes 26, 27 formed on both main surfaces of the cut rectangular quartz plate 25, and extraction electrode portions extending from the vibration electrodes 26, 27 to the other end.

The crystal resonator 2 is electrically connected to the conductive adhesives 21a and 22a via bump members formed on the crystal resonator electrode pads 21 and 22 to secure a gap.
(22a does not appear in the figure). It should be noted that a bump member may be formed on the tip side of the crystal unit 2 to maintain a distance between the crystal unit 2 and the surface of the container 1.

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

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

The circuit element 7 includes an oscillation inverter, an IC chip having at least an amplification inverter, a load capacitance of an oscillation circuit, a capacitor for absorbing power supply noise and adjusting the waveform of output oscillation, For example, a resistance element constituting a feedback circuit of an oscillation circuit can be exemplified. Note that I
Instead of using the C chip, a discrete transistor may be used. In addition, a resistor and a part of a capacitor can be integrated in an IC chip by an IC integration technique.

For example, an IC chip is formed on an 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 a capacitor or a resistor is electrically conductively bonded. It is joined through materials.

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

In the above-described example, in order to compensate for the temperature characteristic inherent in the crystal unit 2, compensation data is written in the IC chip, which is the circuit element 4, and appropriate frequency compensation is performed according to the ambient temperature. It is an IC chip. Therefore, FIG.
As shown in (1), a data terminal 16 for writing compensation data is formed on the side surface of the container 1.

According to the crystal oscillator having the above configuration, the crystal unit 2 and the circuit element 4 are arranged in different accommodation regions, that is, the accommodation environment in which the crystal unit 2 is arranged is changed. 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.
Since the oscillator is housed in the oscillator, the height can be reduced in the thickness direction of the oscillator.

The circuit element 4 is disposed in the cavity 11 immediately below the position where the crystal unit 2 is disposed. In particular, the circuit element 4 performs a switching operation. Moreover, when trying to reduce the thickness of the container 1,
A stray capacitance occurs around the vibrating electrode 27 of the crystal resonator 2.

In this respect, as in the present invention, a conductor 2 having a ground potential is provided inside the container 1 between the crystal unit 2 and the circuit element 4.
3 are arranged. For this reason, generation of stray capacitance parasitic on the vibrating electrode 27 of the crystal resonator 2 or fluctuation of the stray capacitance can be effectively prevented, and a stable vibration operation of the crystal resonator 2 becomes possible.

The conductor 23, that is, a conductor film 23 a 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, A via-hole conductor 23c is formed so as to supplement the gap between the ring-shaped conductor films 23b. Moreover,
The conductor 23 is provided on the peripheral surface of the cavity 11 (the container 1).
Is connected to a terminal electrode 13 having a ground potential formed on the bottom surface of the IGBT.

In this way, high frequency noise generated from the circuit element 4 performing the switching operation is particularly cut off and effectively prevented from being emitted to the outside.

The conductor film 31 for sealing is also connected to the ground potential. As a result, the metal cover 3 is also at the ground potential. The generation of parasitic stray capacitance can be reduced, and no fluctuation occurs in the equivalent capacitance component of the crystal unit 2.

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

Further, a terminal electrode 1 having a ground potential is provided on the peripheral surface of the cavity 11 of the container 1 (the bottom surface of the container).
3 and a terminal electrode 12 serving as a power supply terminal, and in addition, a terminal electrode serving as a control terminal and an oscillation output terminal are formed. For this reason, 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.

FIGS. 1 and 2 show an example in which the crystal unit 2 and the circuit element 4 are directly housed and arranged in the container 1, and FIGS.
Is an example in which only the crystal unit 2 is arranged in the container 1 and the circuit element 4 is mounted on the base substrate 7 side.

In FIGS. 3 to 5, reference numeral 6 denotes a container;
Is a base substrate, and 41 to 43 are circuit elements.

As compared with the container 2 shown in FIG. 2, the wiring pattern inside the cavity portion 11, the electrode pads, the internal conduction paths 14, 15, the data terminal, and the terminal electrode 1 at the ground potential
Terminal electrodes other than 3 are eliminated, and the whole is greatly simplified.

The container 6 includes, for example, a plurality of ceramic layers 6.
a to 6d are laminated. And container 6
A concave cavity portion 61 is formed on the back surface of the. The quartz oscillator 2 is mounted on the surface of the container 6 as described above, and is hermetically sealed with a metal lid 6.

On the inner surface of the cavity 61, a conductor film 62 having a ground potential is formed.

The electrode pad 21 for the crystal unit is provided around the opening of the cavity 61 (the bottom surface of the container 6).
(22 is not shown in the figure) input and output 64, 6 connected to
5 (65 does not appear in the figure), a terminal electrode 63 having a ground potential connected to the conductive film 62 and, if necessary, the sealing conductive film 31 is formed.

Such a container 6 has a plurality of rectangular green sheets forming the container front side and a frame-shaped green sheet forming the container bottom side, on which a predetermined conductor film including a predetermined via-hole conductor is formed. The green sheets are laminated and pressed, and are further integrally baked.

The conductor film includes the electrode pads 21 and 22, the shielding conductor film 31, the conductor film serving as the conductor film 62, the input / output terminal electrodes 64 and 65, the conductor film serving as the ground potential terminal electrode 63, and Electrode pads 21 and 22 and input / output electrodes 6
For example, conductors for connecting the conductive films 4 and 65, internal conductive paths 66 and 67 serving as the conductive film 62 and the terminal electrode 63 at the ground potential are exemplified.

In these, through holes are formed in predetermined green sheets as necessary, and the through holes are filled with a conductive paste such as silver, copper, tungsten, or molybdenum, and silver, copper, or the like is formed on the green sheets. It is formed by printing with a conductive paste such as tungsten or molybdenum.

Such green sheets are laminated and pressed,
Baking is performed in a predetermined atmosphere, and Ni plating, Au plating, or the like is performed on each conductive film as necessary.

Incidentally, of the inner wall surface of the cavity 61,
The formation of the conductor film 62a on the surface serving as the ceiling surface in FIG. 4 can be relatively easily formed by forming the conductor film on the green sheet since it is a flat surface. In addition, the conductor film 62b is formed on one surface of the inner wall surface of the cavity portion 61 on a vertical surface which is a side surface, when the conductor film is printed on the frame-shaped green sheet, the inner surface of the frame is formed by dripping with a conductive paste. can do.

The base substrate 7 has a predetermined wiring pattern 72 formed on a substrate 71 made of ceramic or glass epoxy resin, and various circuit elements constituting an oscillation circuit for controlling an oscillation operation based on the vibration of the quartz oscillator 2. 41-4
3 are arranged. Among the circuit elements 4, for example, the circuit element 41 can be exemplified by an IC chip in which at least an oscillation inverter and an amplification inverter are integrated. Examples of the circuit element 42 include a capacitor that forms a load capacitance of an oscillation circuit, absorbs power supply noise, adjusts the waveform of output oscillation, and a resistance element that forms a feedback circuit of the oscillation circuit. The circuit elements 41 and 42 are arranged near the center of the base substrate 7, particularly so as to be concealed by the cavity 61 of the container 6. On the other hand, the circuit element 4
Reference numeral 3 denotes a circuit element arranged on the base substrate 7 outside the container 6, for example, a circuit element for enhancing the function using the output of a crystal oscillator. Examples include a PLL element, a filter element, and various converters.

As an alternative to the above-mentioned IC chip, a transistor as a discrete component may be used. Further, a resistor and a part of the capacitor can be integrated in the IC chip 41 by an IC integration technology.

When a ceramic substrate is used as the substrate 71, the wiring pattern 72 is formed by printing and printing a conductive paste containing silver or copper as a main component. Also, the substrate 7
1. In the case of glass-epoxy resin, the wiring pattern 7
2 is formed of a copper foil or the like.

The wiring pattern 72 includes a conductor constituting a predetermined oscillation circuit, an electrode pad on which the circuit elements 41 to 43 are mounted, a terminal electrode 63 at the ground potential of the container 6, and an input / output electrode 6
These are connection pads that are connected to the terminals 4 and 65 and terminals that are connected to an external circuit.

For example, as shown in FIG.
2a, the circuit element 41 as an IC chip, the electrode pad 72b, the circuit element 42, and the bonding pad 72.
The input / output electrode 64 of the container 6 and the electrode 63 of the ground potential are respectively joined to c and 72d.

More specifically, each electrode pad 72b, 72
C, 72d is coated with cream solder or the like. First, the circuit element 42 is mounted on the substrate 71, and bonding is performed by reflow processing.

Next, a bump is formed on the electrode portion of the circuit element 41 such as an IC chip, a conductive adhesive is applied to the bump, and the bump is placed on the electrode pad 72a of the substrate 71, and the bonding is performed by heat treatment. Do.

Then, the container 6 in which the crystal unit 2 is hermetically sealed and the base substrate 7 on which the circuit elements 41 to 43 are mounted are joined by a conductive joining member 8 such as solder to form a crystal. An oscillator is configured.

On the surface of the base substrate 7, the circuit elements 41, 4
2 is accommodated in the cavity 61 of the container 6, and the input electrode 64 and the electrode pad 72c are arranged so that the terminal electrode 63 of the earth potential and the pad 72d are aligned with each other. Do.

Since the cream solder previously applied for bonding the circuit element 42 is used as the conductive bonding member 8, in bonding the container 6 and the base substrate 7,
In particular, application of the conductive bonding member 8 is not required. Further, the circuit element 43 mounted on the base substrate 7 not accommodated in the container 6 may be mounted when the container 6 and the base substrate 7 are joined.

Further, when the supply amount of the conductive resin material or the cream solder described above is insufficient, the material of the conductive bonding member 8 is changed to a material that becomes the conductive bonding member 8 before bonding the two. It may be supplied and applied.

The circuit element 41, which is an IC chip,
Although face bonding in which conductive bumps are formed on the mounting bottom surface, bonding may be performed by wire bonding.

According to such a structure, as in the case of the crystal oscillator shown in FIGS. 1 and 2, the crystal oscillator 2 and the circuit element 4 are arranged in different housing areas and in the thickness direction. Therefore, stable operation of the crystal resonator 2 and reduction in height in the thickness direction of the oscillator can be achieved.

The ground potential wiring pattern 72 d of the base substrate 7 is formed of the conductive bonding member 8 and the ground potential terminal electrode 6.
3, the conductor film 23 and the sealing conductor 31 become the ground potential. Therefore, the conductive film 23 surrounding the cavity 61 has a shielding effect. at the same time,
The metal lid 3 is at the ground potential.

That is, there is a conductive film 23a that shields a circuit element 41 such as an IC chip that performs a switching operation immediately below the position where the crystal unit 2 is arranged. For this reason, the occurrence of stray capacitance around the vibrating electrode of the crystal unit 2 and its fluctuation can be effectively suppressed. Since the metal lid 3 also has the ground potential at the same time, the same applies to the upper-side vibrating electrode of the crystal unit 2, and the equivalent capacitance component of the crystal unit 2 does not change at all.

Further, high frequency noise generated from the circuit element 41 performing the switching operation can be cut off by the conductor films 23a and 23b so as to surround the cavity 61 three-dimensionally, and it can be effectively prevented from being emitted outside. .

Further, in the crystal oscillator having the structure shown in FIGS. 3 to 5, the formation of the container 6, the formation of the base substrate 7, and the bonding of both are all performed on one principal surface. As described above, since it is not necessary to arrange the container 6 upside down or mount and connect various circuit elements in a limited space of the cavity portion, the processing is performed very efficiently. Will be.

Further, since the circuit element 41, which is a noise source, is in the cavity 61 of the container 6, it is not necessary to cover the circuit element 43 formed on the base substrate 7 with a metal case. It is also effective for weight reduction.

In FIGS. 3 to 5, the conductor film 23 may be formed by a thin film technique such as vapor deposition of a conductive material instead of the thick film technique.

Further, as shown in FIG. 2, the conductor film 23 is
A flat conductive film, a ring-shaped conductive film, and a via-hole conductor may be formed inside the container 6. If the conductor film 23 is provided on the inner surface of the cavity portion 61, plating is performed on the surfaces of the electrode pads 21, 22 and the sealing conductor film 31, and at the same time, plating adheres to the surface of the conductor film 23, It is disadvantageous in terms of cost. In this regard, forming a conductor film inside the container 6 is very advantageous in terms of cost.

2 and 3 to 5, the conductive film 23 surrounding the cavities 11 and 61 in three dimensions is a flat conductive film located on the upper surface side of the cavities 11 and 61. May be made into a matrix pattern composed of vertical and horizontal strip-shaped conductor films extending in a plane. As shown in FIG. 2, a ring-shaped or horseshoe-shaped conductive film corresponding to the outer shape of the cavity is provided between the ceramic layers serving as the legs of the containers 1 and 6 constituting the cavities 11 and 61. Or a plurality of via-hole conductors may be formed around the cavity to form the conductor film 23b.

[0077]

According to the present invention, a conductor film having a ground potential is formed so as to three-dimensionally surround the cavity portion on the bottom surface of the container. For this reason, it is possible to suppress the leakage of high-frequency noise from the circuit element housed in the cavity to the outside.

In addition, the stray capacitance generated on the vibrating electrode of the quartz oscillator disposed on the surface side of the container can be effectively suppressed.
The fluctuation can be completely suppressed, and stable operation can be performed.

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

[Brief description of the drawings]

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

FIG. 2 is a sectional view of a crystal oscillator according to the present invention.

FIG. 3 is an external perspective view of another crystal oscillator according to the present invention.

4 is a sectional view of a container used for the crystal oscillator shown in FIG.

FIG. 5 is a partial sectional view of FIG. 3;

[Explanation of symbols]

 1, 6... Container part 2. .. quartz resonator 3... Metal lid 7... Base substrate 4... Circuit element 8.

Claims (2)

[Claims] 1. A case-like container having a cavity portion on a bottom surface, a crystal oscillator mounted on the surface of the container, and housed in the cavity portion of the container and controlling an oscillation operation of the crystal oscillator. A crystal oscillator comprising: a circuit element; and a conductor film having a ground potential surrounding the cavity is formed in the container. 2. The crystal oscillator according to claim 1, wherein an earth electrode connected to the conductor film at the earth potential is formed on the peripheral surface of the opening of the cavity of the container.