1. Field of the Invention
The present invention relates to a surface-mounted oscillator, and more particularly, to a technique for reducing the planar dimensions of the surface-mounted oscillator.
2. Description of the Related Art
Since a surface-mounted oscillator is small-sized and lightweight, it is, for example, included in a portable appliance, and widely used as a frequency or time reference source, etc. For example, if a portable appliance to be used is a telephone, a temperature compensated oscillator (TCXO) disclosed by Patent Document 1 is used because of its dynamic environments.
A surface-mounted oscillator is configured to accommodate, in a surface-mounted package, an oscillation element such as a crystal piece, etc., an IC (Integrated Circuit) chip in which an oscillation circuit, a temperature compensation circuit, etc., are integrated, and a circuit element composed as a discrete component such as a capacitor, etc., which cannot be integrated within the IC chip.
The surface-mounted package 4 is configured by comprising concave portions on both of its main surfaces, and by integrating an oscillation element 1, which is sealed with a cover 9 after being accommodated in the concave portion on one of the main surfaces, and the IC chip 2 and the circuit element 3, which are accommodated in the other concave portion.
[Patent Document 1]
Japanese Patent Publication No. 2000-244243
[Patent Document 2]
Japanese Patent Publication No. HEI8-204452
[Patent Document 3]
Japanese Patent Publication No. 2003-179433
[Patent Document 4]
Japanese Patent Publication No. HEI9-298440
Currently, the planar dimensions of a surface-mounted oscillator are, for example, on the order of 3.2 by 2.5 mm, but there is a demand for further reducing the dimensions. Additionally, as an oscillation frequency increases, the size of an oscillation element 1 such as a crystal piece, etc. becomes smaller. However, there is a problem that an increase in planar dimensions cannot be avoided, because an IC chip, and a discrete component such as a capacitor, etc. are arranged on the same flat surface.
An object of the present invention is to provide a surface-mounted oscillator, the planar dimensions of which can be reduced, and which accommodates an oscillation element, an IC chip, and a circuit element (discrete component).
The present invention assumes a surface-mounted oscillator configured by integrally accommodating an oscillation element, an IC chip, and a circuit element in a surface-mounted package, and is characterized in that the oscillation element, the IC chip, and the circuit element are arranged in positions in a direction vertical to a mounting surface of the surface-mounted oscillator.
The surface-mounted package may be configured to comprise a first concave portion that accommodates the oscillation element on a first main surface, and a second concave portion that accommodates the IC chip and the circuit element on a second main surface as opposed to the first main surface.
Or, the surface-mounted package may be configured by joining a first package that accommodates the oscillation element, and a second package that accommodates the IC chip and the circuit element.
Or, the surface-mounted package maybe configured to comprise a concave portion that accommodates the oscillation element, the IC chip, and the circuit element.
Or, the oscillation element may be an oscillation element using bulk wave oscillation, which entirely oscillates, or an oscillation element using surface wave oscillation, only the surface of which oscillates.
According to the present invention, the oscillation element, the IC chip, and the circuit element are arranged in positions in a vertical direction, whereby the planar dimensions of the surface-mounted oscillator can be reduced.
Fundamental principle of the present invention is first described.
In the conventional surface-mounted oscillators, an IC chip 12, and a circuit element 13 composed of a discrete component such as a capacitor, etc. are accommodated by being arranged in a package 10a in a direction horizontal to a mounting surface 14a comprising mounting electrodes not shown.
With an increase in output frequency demanded for a surface-mounted oscillator in recent years, the size of an oscillation element 11 has been decreasing. Additionally, in a temperature compensated oscillator, etc., an IC chip 12 also includes a temperature compensation circuit, etc. Therefore, its size is approximately the same as that of an oscillation element 11 composed of a crystal piece. Accordingly, the planar dimensions of a conventional surface-mounted oscillator are determined by a size obtained by combining areas where the IC chip 12 and the circuit element 13 are respectively mounted.
Considering this point, in a surface-mounted oscillator according to the present invention, respective constituent elements are arranged in positions in a vertical direction.
The circuit element 13 is smaller than the oscillation element 11 and the IC chip 12. Therefore, in the case of the configuration shown in
A temperature compensated oscillator using a multilayer ceramic package is exemplified next as a specific configuration example of the surface-mounted oscillator according to the present invention.
The surface-mounted oscillator shown in
The oscillation element 21 is made of a piezoelectric material such as a crystal piece, etc., and has excitation electrodes not shown on both of main surfaces. For example, drawn electrodes are extended, for example, to both sides of one end of the oscillation element 21. The IC chip 22 is implemented by integrating circuit elements that configure an oscillation circuit having a temperature compensation mechanism not shown. The circuit element 23 is a circuit element that cannot be integrated within the IC chip 22, such as a capacitor used, for example, to form with a resistor a lowpass filter, which removes noise caused by the temperature compensation mechanism, a bypass capacitor which makes a high-frequency component pass through, an inductor used to widen the variable width of a frequency in a voltage controlled oscillator (VCO), and the like. Since the capacitor that forms a lowpass filter requires a large capacity equal to or higher than 1000 pF, it cannot be integrated within the IC chip 22. Accordingly, the capacitor is used as a discrete component. Also the bypass capacitor between a power source and a ground cannot be integrated within the IC chip 22 due to its large capacity. Therefore, the bypass capacitor is used as a discrete component.
In the configuration shown in
With such a configuration, in the surface-mounted oscillator shown in
Note that opposed two sides of the concave portion 26a, which accommodates the IC chip 22, are made open to increase the mounting area of the IC chip 22. If the IC chip 22 is small, the concave portion 26a can be also configured as a concave portion composed of 4 sides without making the two sides open, as a matter of course.
A second preferred embodiment is described next.
The surface-mounted oscillator shown in
A concave portion 26b is provided on the mounting board 33b, and a hole 30b is provided in the central region of the concave portion 26b. The circuit element 23 is accommodated in the hole 30b, and the IC chip 22 is secured to stage portions 31b in the concave portion 26b with flip chip bonding using bumps 28 to cover the circuit element 23.
Then, the side of the concave portion 26b of the mounting board 33b and the side of the bottom of the package 32 are joined with soldering.
In the configuration shown in
In this figure, a surface-mounted package 24c is composed of the same package 32 as that in
Additionally,
In
Also in the configuration shown in
In this figure, a surface-mounted package 24e is configured by the same package 32 as that in
In the cases of the configurations according to the second preferred embodiment shown in
A third preferred embodiment is described next.
The configuration according to the third preferred embodiment is a configuration where an oscillation element 21 such as a crystal piece, etc., and other constituent elements are sealed in the same space.
In
The surface-mounted package 24f comprises stage portions 34f, and a concave portion 26f on an inner wall. Additionally, a hole 30f is provided in the central region of the bottom of the concave portion 26f.
The circuit element 23 such as a capacitor, etc. is accommodated in the hole 30f, and the IC chip 22 is secured to the stage portions 31f within the concave portion 26f to cover the circuit element 23. Additionally, after the oscillation element 21 is accommodated to cover the IC chip 22, for example, by securing one end of the oscillation element 21 to a stage portion 34f on the inner wall, it is sealed with a cover 29.
In
The first to the third preferred embodiments described up to this point refer to the cases where only one circuit element 23 such as a capacitor, etc. exists. However, a plurality of circuit elements 23 can be similarly accommodated also in the case of a configuration where an oscillator uses the plurality of circuit elements 23.
Normally, the size of a circuit element 23 is much smaller than an oscillation element 21 and an IC chip 22. Accordingly, as shown in
In this figure, the hole 26i in which the plurality of circuit elements 23 can be mounted is provided in the center of a concave portion 26 accommodating the IC chip 22 in the surface-mounted package 24i, and the two circuit elements 23-1 and 23-2 are accommodated in this hole 26i. Also in the surface-mounted oscillators having the configurations according to the second and the third preferred embodiments, which are shown in
The above described embodiments refer to the cases where the crystal piece using bulk wave oscillation is used as the oscillation element 11. However, in the surface-mounted oscillators represented as the respective embodiments, an oscillation element using surface wave oscillation such as a SAW (Surface Acoustic Wave), etc. may be used as the oscillation element other than the element using bulk wave oscillation.
In this figure, the side of one main surface of an oscillation element 35 using a SAW, on which excitation electrodes are formed, is secured to the bottom of a concave portion of a surface-mounted package 24j with flip chip bonding using bumps not shown. Similarly, also in the surface-mounted oscillators having the configurations according to the second and the third preferred embodiments, which are shown in
At this time, the hermetic of the oscillation element using a SAW, etc. can be low in comparison with the oscillation element using bulk wave oscillation. Therefore, a resin may be available as the surface-mounted package 24j other than multilayer ceramic.
The above provided description refers to the configurations where the IC chip 22 is secured with flip chip bonding. However, the IC chip 22 may be connected with wire bonding.
Additionally, a resinous agent not shown may be added to protect the IC chip, and the circuit element 23 such as a capacitor, etc. on demand.
In the above described preferred embodiments, the oscillation element 21, the IC chip 22, and the circuit element 23 such as a capacitor, etc. are arranged in a vertical direction in all the cases, whereby the planar dimensions can be held small.
Number | Date | Country | Kind |
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2003-279446 | Jul 2003 | JP | national |
Number | Name | Date | Kind |
---|---|---|---|
5500628 | Knecht | Mar 1996 | A |
6456168 | Luff | Sep 2002 | B1 |
6759913 | Biernacki | Jul 2004 | B1 |
Number | Date | Country |
---|---|---|
8-204452 | Aug 1996 | JP |
09-298440 | Nov 1997 | JP |
2000244243 | Sep 2000 | JP |
2003179433 | Jun 2003 | JP |
Number | Date | Country | |
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20050017811 A1 | Jan 2005 | US |