JP3246785B2 - 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 structure of a crystal oscillator, and more particularly to a package structure of a crystal oscillator and an oscillator which can be miniaturized and highly stabilized.

[Prior art]

The structure of a conventional crystal oscillator will be described with reference to the drawings. Hereinafter, description will be made with reference to FIGS. 4 and 5.

FIG. 4 is a sectional view showing a temperature-compensated crystal oscillator. A semiconductor integrated circuit chip (hereinafter, referred to as an IC chip) 13 for driving a quartz oscillator and a capacitor 17 are provided on a substrate 11 made of a metal or a ceramic material having insulating terminals. This IC chip 13 is a wire 23
Is connected to the substrate 11.

The crystal blank 15 is connected to a crystal blank support plate 43 by a conductive adhesive 37.

The components of the crystal blank 15, the IC chip 13, and the capacitor 17 are made of a metal cover 51 to prevent the influence of humidity and to perform electromagnetic shielding.
Is hermetically sealed with a bonding agent 39.

The atmosphere 45 in the container is filled with an inert gas. Further, the electrical connection between the external substrate and the crystal oscillator is made at the lead portion 29.

FIG. 5 is a sectional view showing another conventional example of a temperature compensated crystal oscillator. The difference from the conventional example of FIG. 4 is that the quartz oscillator 49 for accommodating a quartz piece (not shown) is sealed in a dedicated airtight container.

[0008]

In recent years, various electronic products using crystal-applied products have been increasingly used in portable devices, and are becoming smaller, thinner, and more sophisticated. Correspondingly, crystal oscillators are required to have high stability and surface mount (SMD) as well as miniaturization and thinning.

[0009] In particular, for mobile phones and the like, which are expected to spread, a large number of transmission / reception frequencies required for telephone calls are required as the number of subscribers increases. However, since radio waves are finite, it is necessary to secure a large number of frequencies in the allocated frequency region.

[0010] Therefore, in order to achieve the above-mentioned problems, a crystal oscillator, which is a frequency reference source of a cellular phone, requires minimization of a frequency deviation over a wide range of temperatures and minimization of aging of a frequency. In addition, miniaturization of the crystal oscillator is indispensable.

The minimization of the frequency deviation over a wide range of temperatures is realized as a temperature-compensated crystal oscillator in which the inherent frequency deviation of the crystal unit can be corrected on the oscillation circuit side.

On the other hand, minimization of the secular change of the frequency and miniaturization are largely due to the problem of the crystal resonator itself. However, regarding minimization of aging and miniaturization,
It has the problems described below.

In the conventional example shown in FIG.
1 and is close to the IC chip 31, which is advantageous for thinning and miniaturization.

However, the secular change of the frequency of the crystal blank 15 is caused by the gas released from the adhesive fixing the IC chip 13 and the capacitor 17 and the gas released from the substrate 11 and the cover 51 having a large area. Fifteen surfaces are contaminated.

As a result, the aging of the frequency is determined to be 1 ppm / year or less as shown by the line A in the graph of FIG. 6, but the aging of the frequency is 1 ppm / year as shown by the B line due to the above-mentioned factors. More than a year.

On the other hand, in the conventional example shown in FIG.
Is enclosed in a special container and has a finished product whose frequency has been measured over time.

For this reason, a good frequency aging characteristic is obtained as shown by the line A in the graph of FIG.

However, since the crystal oscillator 49 is enclosed in a dedicated container, it is difficult to reduce the size of the crystal oscillator, and it is inevitable that the external dimensions of the crystal oscillator become large.

An object of the present invention is to solve the above-mentioned problems and to provide a crystal oscillator capable of minimizing aging of a crystal resonator and achieving further miniaturization and thickness reduction.

[0020]

To achieve the above object, the oscillator according to the present invention employs the following configuration.

In the oscillator of the present invention, a first lid for hermetically sealing a crystal blank and a second lid for a crystal oscillator for covering an IC chip and a capacitor required for driving the crystal blank are mounted on the same substrate. It is characterized by doing.

An oscillator according to the present invention comprises a first lid for hermetically sealing a crystal blank, an IC chip required for driving the crystal blank, and a crystal oscillator for covering the first lid and the IC chip. Is characterized in that the second lid is provided on the same substrate as the first lid.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing a crystal oscillator according to a first embodiment of the present invention, and FIG. 2 is a sectional view showing a crystal oscillator according to the first embodiment of the present invention. FIG. 1 shows a state where the first lid 31 and the second lid 33 are not provided, and FIG. 2 shows a completed state where the first lid 31 and the second lid 33 are provided. Hereinafter, description will be made with reference to FIGS. 1 and 2 alternately.

A concave portion is provided on the portion of the substrate 11 where the crystal blank 15 is to be disposed, if necessary.
Is used to connect to the electrode lead 27.

In order to form a crystal resonator, the first lid 31 for sealing the crystal piece 15 is hermetically sealed to the substrate 11 by a sealing portion 35. The atmosphere 45 in the container for accommodating the crystal blank 15 is a vacuum or an inert gas atmosphere.

Sealing portion 35 for hermetically sealing crystal blank 15
It is important that the airtightness and low temperature are important in consideration of the influence on the crystal blank 15, and an organic adhesive, a eutectic alloy, seam welding, or the like is used for bonding.

On the other hand, the bonding surface 1 of the first lid 31 and the substrate 11
As the material 9, metal, ceramics, or glass is used depending on the joining method.

As described above, the quartz oscillator is mounted on the substrate 11.
Since it is configured as a single container, a very thin crystal resonator structure can be achieved.

The aging of the frequency of the crystal oscillator is determined by the first
It is confirmed at the stage where the lid 31 is provided, and good characteristics can be achieved as indicated by the line A in the graph of FIG.

On the other hand, an IC chip 13 for driving a quartz oscillator
And the capacitor 17 are arranged on the substrate 11, and the IC chip 13 is connected to the pad 25 by a wire 23.

In this embodiment, the IC chip 13 and the pad 25
Although the example of the connection using the wire 23 is described as the connection with, a direct connection using a conductive adhesive, a eutectic alloy, or the like is also possible.

The capacitor 17 is covered with the first lid 33 and the IC chip 13 which cover the crystal blank 15 placed on the substrate 11 with the second lid 33.

The purpose of providing the second lid 33 is to stabilize the atmosphere 47 in the container and the electromagnetic shield.

Here, if the IC chip 13 is resin-molded, the inside of the second lid 33 does not need to be hermetically sealed, and the atmosphere 47 in the container may be an air atmosphere.

In the present embodiment, the second lid 33 is an example in which the second lid 33 is hermetically sealed. The joining of the second lid 33 to the substrate 11 is performed at the joining portion 39 and low-temperature joining is performed.

Next, the structure of a crystal oscillator according to a second embodiment of the present invention will be described with reference to the sectional view of FIG.

A concave portion for disposing the crystal blank 15 is provided on the substrate 11, and the crystal blank 15 is fixed by a conductive adhesive 37.

The first lid 31 is joined to the substrate 11 at the sealing portion 35, and the atmosphere 45 in the container for accommodating the crystal blank 15 is a vacuum or an inert gas atmosphere as in the first embodiment. .

The method of bonding the first lid 31 to the substrate 11 and the materials thereof are the same as those described above with reference to FIGS.

The IC chip 13 is placed on the first lid 31 using a bonding agent 41 and connected to the substrate 11 using wires 23.

As described above, the IC chip 13 is attached to the first lid 3.
1, the external dimensions in the planar direction are reduced, and the crystal oscillator can be miniaturized. The second lid 33 is the IC
It may be provided so as to cover the chip 13.

[0042]

As is apparent from the above description, according to the present invention, the insulating terminal of the crystal oscillator container is used together with the oscillator substrate, and the crystal piece is hermetically sealed by the first lid alone. Stop.

For this reason, the volume of the container is reduced, the influence of gas and moisture from other than the crystal piece is reduced, the frequency aging of the crystal piece is suppressed low, and a high performance crystal oscillator of 1 ppm or less per year can be realized. . Further, since the substrate uses both the crystal oscillator and the oscillator, the thickness can be reduced.

Further, in the second aspect, the semiconductor integrated circuit chip is provided on the first lid, so that further miniaturization is possible.

Further, if the oscillator is hermetically sealed, the quartz oscillator is double-sealed. Therefore, long-term frequency aging can be further improved. As a result, the oscillator of the present invention has a great effect on a small, thin, and highly stable crystal oscillator.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a structure of a crystal oscillator according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing the structure of the crystal oscillator according to the first embodiment of the present invention.

FIG. 3 is a sectional view showing a structure of a crystal oscillator according to a second embodiment of the present invention.

FIG. 4 is a sectional view showing a structure of a crystal oscillator according to a conventional example.

FIG. 5 is a cross-sectional view showing another conventional example of a temperature compensated crystal oscillator.

FIG. 6 is a graph showing frequency aging for explaining the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Substrate 13 Semiconductor integrated circuit chip 15 Quartz piece 31 First lid 33 Second lid

Claims (2)

(57) [Claims] 1. A crystal blank and a half for driving the crystal blank.
A crystal oscillator in which a conductor integrated circuit chip is placed on a substrate.
A first lid for hermetically sealing the quartz piece;
A circuit chip and a second lid for covering the first lid,
A crystal oscillator provided on a plate . To 2. A on the first lid for hermetically sealing crystal blank, set up a semiconductor integrated circuit chip necessary for driving of the <br/> crystal piece,
Wherein the first lid and the semiconductor integrated circuit a second lid for crystal oscillator covering the chip crystal oscillator, characterized in that installed in the first cover and the same substrate.