JPH09260948A - Crystal oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress oscillation frequency fluctuation caused by fluctuation in the stray capacitance a substrate part by providing an opening at the substrate part corresponding to a gap between the input and output electrodes of a crystal, oscillator. SOLUTION: A crystal oscillator 2 and a control element 3 are mounted on a substrate 1. Input and output electrodes 4 at both the terminals of the crystal oscillator 2 are soldered and electrically connected to a pattern 5 on the substrate 1, and an electrode 6 of the control element 3 is soldered and electrically connected as well. At the section of the substrate 1 corresponding to the gap between the input and output electrodes 4 of the crystal oscillator 2, the opening is formed by providing a groove 7 from the left end of the substrate 1. Thus, moisture or the like is absorbed and the oscillation frequency fluctuation caused by the change in the stray capacitance between the input and output electrodes 4 of the crystal oscillator can be suppressed. When the groove 7 is further extended to right to reach the lower face of the control element 3, a temperature detecting element can detect the temperature through this groove and accuracy can be further improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crystal oscillator.

[0002]

2. Description of the Related Art In a crystal oscillator, a crystal oscillator and its control element are mounted on a substrate, and the oscillation frequency is controlled by the control element to be constant.

[0003]

[Problems to be Solved by the Invention]
The output electrodes are coupled by the stray capacitance of the substrate, and if the stray capacitance of the substrate fluctuates over time, there is a problem that the oscillation frequency fluctuates greatly despite control by the control element.

Therefore, the present invention is intended to suppress the fluctuation of the oscillation frequency.

[0005]

In order to achieve this object, the present invention is to provide an opening in the substrate portion corresponding to the input and output electrodes of the crystal unit.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The invention according to claim 1 of the present invention is directed to a substrate, a crystal oscillator mounted on the substrate, electrically connected to the crystal oscillator, and on the substrate. And a control element mounted on the crystal unit,
A crystal oscillator having input and output electrodes at both ends thereof, and an opening provided in the substrate portion corresponding to the input and output electrodes, wherein an opening is provided in a substrate portion between the input and output electrodes of a crystal oscillator. Since the coupling between the input and output electrodes due to the stray capacitance due to the substrate portion is less likely to occur, it is possible to suppress the variation in the oscillation frequency of the crystal oscillator due to the variation in the stray capacitance with the aging of the substrate.

The invention according to claim 2 is the crystal oscillator according to claim 1, wherein the opening is formed by a groove reaching from the end face of the substrate to at least the lower surface of the crystal resonator. The openings are easily formed.

Further, the invention according to claim 3 is the crystal oscillator according to claim 2, wherein a temperature detecting element is integrated in the control element, and a groove reaching the lower surface of the control element is provided. Since the lower surface of the element is provided with the opening by the groove, the temperature detecting element in the control element can easily detect the ambient temperature, and as a result, the temperature control accuracy of the crystal oscillator is improved.

Further, according to a fourth aspect of the present invention, a shield cover for covering the control element and the crystal unit is mounted on the substrate, and the lower side of the outer peripheral wall of the shield cover is provided on both sides of the groove on the substrate. Fixed claim 2 or 3
In the crystal oscillator according to 1, the both sides of the groove of the substrate are fixed to the lower side of the outer peripheral wall of the shield cover,
The stress that tends to change the distance between the both sides of the groove of the substrate or the stress that causes the both sides to vertically deform is unlikely to occur, so that the crystal oscillator and the control element are not separated from the substrate.

In the invention according to claim 5, conductive patterns are provided on both sides of the groove on the substrate, and the conductive patterns are
The crystal oscillator according to claim 4, wherein the lower side of the outer peripheral wall of the shield cover is fixed with a conductive adhesive, and the shielding effect is enhanced by fixing the conductive pattern and the shield cover with the conductive adhesive. .

Further, the invention according to claim 6 is the crystal oscillator according to claim 4 or 5, wherein a protrusion that protrudes into the groove is formed on the lower side of the outer peripheral wall of the shield cover. It is hard to get and has a high shielding effect.

Further, the invention according to claim 7 is the crystal oscillator according to any one of claims 1 to 6, wherein the substrate is composed of a multilayer substrate, and the inner surface of the groove is coated with resin. It is difficult for moisture or the like to infiltrate from the groove portion into the multilayer substrate portion, so that the stray capacitance of the substrate does not easily fluctuate, and the fluctuation of the oscillation frequency of the crystal oscillator can be suppressed.

An embodiment of the present invention will be described below with reference to FIG. In FIG. 1, reference numeral 1 is a substrate on which a crystal oscillator 2 and its control element 3 are mounted. The crystal oscillator 2 is electrically connected by soldering the input and output electrodes 4 at both ends thereof to the pattern 5 on the substrate 1. The electrode 6 of the control element 3 is also electrically connected to the pattern 5 by soldering.

That is, although not shown in the figure, a temperature detecting element is integrated in the control element 3, and by detecting the ambient temperature by this temperature detecting element, it is possible to suppress the oscillation frequency from varying. I am doing it.

An opening is formed in a portion of the substrate 1 corresponding to the space between the input and output electrodes 4 of the crystal unit 2 by providing a groove 7 from the left end of the substrate 1.

That is, the substrate 1 is made of, for example, a synthetic resin, and when moisture or the like is absorbed due to a change with time, the stray capacitance between the input and output electrodes 4 of the crystal oscillator 2 changes, and the oscillation frequency fluctuates accordingly. Therefore, in order to suppress the influence of the stray capacitance, an opening is provided in the portion of the substrate 1 corresponding to the input / output electrode 4.

If the groove 7 is further extended to the right and reaches the lower surface of the control element 3, the temperature detecting element in the control element 3 can detect the ambient temperature via the groove 7. As a result, the temperature control accuracy is further improved.

Next, a metallic shield cover 8 for covering the control element 3 and the crystal unit 2 is mounted on the substrate 1, and the lower side of the outer peripheral wall of the shield cover 8 is formed in the groove 7 on the substrate 1. Since it is fixed to the shield patterns 9 on both sides by soldering, both side portions of the groove 7 of the substrate 1 are fixed to the lower side of the outer peripheral wall of the shield cover 8, and as a result, the distance between both side portions of the groove 7 of the substrate 1 is fixed. The stress that is about to change,
Alternatively, the stress that tends to vertically deform the both side portions is unlikely to be generated, so that the crystal resonator 2 and the control element 3 are not separated from the substrate 1.

Further, the shield effect is enhanced by fixing the left and right shield patterns 9 and the shield cover 8 of the substrate 1 with a conductive adhesive such as solder.

Further, since the projecting piece 8a which projects into the groove 7 is formed on the lower side of the outer peripheral wall of the shield cover 8, the deformation of the substrate 1 is unlikely to occur and the shielding effect is enhanced.

When the substrate 1 is formed of a multi-layer substrate, it is preferable to coat the inner surface of the groove 7 with a resin. With this structure, moisture or the like may enter from the groove 7 portion to the multi-layer substrate portion. Therefore, the stray capacitance of the substrate 1 does not easily fluctuate, and the fluctuation of the oscillation frequency of the crystal oscillator can be suppressed.

The substrate 1 is provided with connection terminals 10 at four locations.

[0023]

As described above, according to the present invention, the substrate, the crystal oscillator mounted on the substrate, the control element electrically connected to the crystal oscillator and mounted on the substrate. And the crystal resonator has an input electrode and an output electrode at both ends thereof, and an opening is provided in the substrate portion corresponding to the input and output electrodes.
Coupling due to stray capacitance due to the substrate portion between the output electrodes is unlikely to occur, and fluctuations in the oscillation frequency of the crystal oscillator due to fluctuations in the stray capacitance over time of the substrate can be suppressed.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of an embodiment of the present invention.

[Explanation of symbols]

 1 substrate 2 crystal oscillator 3 control element 4 input, output electrode 7 groove 8 shield cover 8a projecting piece 9 shield pattern

Claims (7)

[Claims] 1. A crystal oscillator, comprising: a substrate; a crystal oscillator mounted on the substrate; and a control element electrically connected to the crystal oscillator and mounted on the substrate. Has input and output electrodes at both ends, and this input,
A crystal oscillator in which an opening is provided in the substrate portion corresponding to between output electrodes. 2. The crystal oscillator according to claim 1, wherein the opening is formed by a groove extending from the end surface of the substrate to at least the lower surface of the crystal resonator. 3. The crystal oscillator according to claim 2, wherein a temperature detecting element is integrated in the control element, and a groove reaching the lower surface of the control element is provided. 4. The method according to claim 2, wherein a shield cover for covering the control element and the crystal unit is mounted on the substrate, and the lower side of the outer peripheral wall of the shield cover is fixed to both sides of the groove on the substrate. The crystal oscillator described. 5. The crystal oscillator according to claim 4, wherein a conductive pattern is provided on both sides of the groove on the substrate, and the lower side of the outer peripheral wall of the shield cover is fixed to the conductive pattern with a conductive adhesive. 6. The crystal oscillator according to claim 4, wherein a projecting piece that projects into the groove is formed on the lower side of the outer peripheral wall of the shield cover. 7. The crystal oscillator according to claim 1, wherein the substrate is a multi-layer substrate and the inner surface of the groove is coated with resin.