JPH09214249A - Ceramic package structure for oscillator module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize a module by arranging an electrode where a capacitor is arranged on the outer surface of a package, an opposite electrode which is oppositely arranged by sandwiching at least a part of the ceramic material of the package and the ceramic material of the package which is arranged between the electrodes. SOLUTION: A plate-like hollow 5b which is comparatively shallow is formed at the bottom of a ceramic base 5a constituting the package 5. One electrode 10a constituting a capacitor for capacitance adjustment 10 is laminated and arranged in the hollow. Furthermore, an electrode 10b constituting the capacitor for capacitance adjustment 10 is buried in the ceramic base 5a so that it faces the electrodes 10a. A ceramic dielectric being a part of the ceramic base 5a is arranged between the electrodes. The area of the electrode 10a is reduced and the capacitance of the capacitor can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oscillator module, and more particularly to a ceramic package structure for an oscillator module having a capacitance adjusting function.

[0002]

2. Description of the Related Art Generally, when the frequency of an oscillator is changed, the capacitance which is the reactance of the resonance circuit is changed to change the resonance frequency of the resonance circuit, and thereby the oscillation frequency is changed. A typical example of changing the capacitance to finely adjust the resonance frequency is to change the capacitance by directly changing a variable capacitor provided on the resonance circuit.

FIG. 4 shows an example of a circuit configuration of an oscillator module having a capacitance adjusting function. In FIG. 4, 1 is a crystal oscillator which is a resonator of the oscillator, 2 is amplification for oscillation, and others. Semiconductor element with the function of C
x is a variable capacitor for capacitance adjustment, R is a resistor, and Cg, Cd, Cl, and C2 are capacitors.

The variable capacitor Cx is connected in parallel with the capacitor Cg, one end of which is grounded, the other end of which is one end of the crystal resonator 1, one end of the resistor R and the semiconductor element 2.
Is connected to the input terminal of The output terminal of the semiconductor element 2 is connected to the output terminal T _OUT via the capacitor C1, and is also connected to the other end of the resistor R, the other end of the crystal resonator 1 and one end of the capacitor Cd. The other end of this capacitor Cd is grounded. The semiconductor element 2 is also connected to the power supply voltage terminal Vcc and the ground, and the capacitor C
Similarly, 2 is also connected to the power supply voltage terminal Vcc and the ground.

A concrete package structure of the oscillator module of FIG. 4 is shown in FIG. 5, in which the same components as those in FIG. 4 are designated by the same reference numerals. In FIG. 5, a variable capacitor C having a capacitance adjusting function
The x is stored in a relatively deep recess 6 provided outside the package 5. In this way, the variable capacitor Cx
Is provided outside the package 5 so that the capacitance can be adjusted including the variation caused during assembly, and the capacitance can be adjusted even after the module is assembled.

As the variable capacitor Cx, a trimmer capacitor with a rotary or a chip capacitor is used, and the frequency is adjusted by directly operating the trimmer capacitor or by pattern trimming the chip capacitor to change the capacitance. Be seen.

[0007]

However, in such a package structure, it is necessary to provide a relatively deep recess 6 for accommodating the variable capacitor for adjusting the capacitance outside the package, and therefore, the ceramic package. It has a problem that the structure of is complicated.
Further, providing a variable capacitor for capacitance adjustment outside the package requires securing a space for this component, especially a space in the height direction, and from the viewpoint of miniaturization and high density of the module. It becomes a problem.

[0008]

In order to solve such a problem, a capacitor for adjusting capacitance is arranged opposite to an electrode arranged on the outer surface of the package with at least a part of the ceramic material of the package being sandwiched therebetween. Also, there is provided a ceramic package structure for an oscillator module, characterized in that it is constituted by a counter electrode and a ceramic material of a package arranged between these electrodes.

With this configuration, the capacitance can be adjusted in the same manner as in the conventional case by pattern-trimming the electrodes arranged outside the package, and the space in the height direction like the conventional case is required. Therefore, it is possible to obtain a ceramic package structure suitable for miniaturization and high density of the module.

[0010]

1 shows one embodiment of a ceramic package structure for an oscillator module according to the present invention, in which the same parts as those in FIGS. 4 and 5 are designated by the same reference numerals. There is. In FIG. 1, a relatively shallow dish-shaped recess 5b is formed on the bottom surface of the ceramic base 5a that constitutes the package 5, and one of the electrodes that constitutes the capacitance adjusting capacitor 10 characterized by the present invention is formed in this portion. 10a are stacked and arranged. The electrode 10a has a flat plate shape and is formed by vapor-depositing a metal or by a known method. In addition, inside the ceramic base 5a, the electrode 10 that constitutes the capacitance adjusting capacitor 10 faces the electrode 10a.
b is embedded. This electrode 10b is formed to be slightly larger than the electrode 10a in this example, and a ceramic dielectric, which is a part of the ceramic base 5a, is arranged between both electrodes.

According to this structure, after the oscillator module is assembled, the electrodes 1 arranged on the outer surface of the package 5 are arranged.
0a is pattern-trimmed with a laser or the like, whereby the area of the electrode 10a can be reduced as shown in FIG. 2 to reduce the capacitance of the capacitor Cx, and the capacitance of the oscillator module can be adjusted as in the conventional case. In other words, by adjusting the electrode area of the electrode 10a, the reactance of the resonance circuit changes, and the oscillation frequency can be adjusted. It is possible to obtain a ceramic package structure suitable for miniaturization and high density of a module without requiring a space in the height direction like a dent unlike in the past.

The capacitance of the capacitor 10 obtained by the present invention is determined by the dielectric constant of the ceramic material of the package 5, the distance between the electrodes, and the facing area of the electrodes, and it is generally known by the following equation. Is. C = ε ₀ · ε · S / d C: formed capacitance ε ₀ : relative permittivity ε: permittivity of ceramic S: facing electrode area d: interelectrode distance

According to the present invention, the distance between electrodes and the facing area can be arbitrarily set with respect to a specific ceramic material which can be selected as a package material, and further, the set position and the size can be set according to the structure of the package. It can be arbitrarily selected within the range permitted by the circuit configuration.

FIG. 3 shows another embodiment of the present invention. The difference from FIGS. 1 and 2 is that the ceramic base 5a is used.
The electrode 10a disposed on the bottom surface of is used as an intermediate electrode, the electrode 10b embedded in the ceramic base 5a is divided into 10b1 and 10b2, and these are used as the electrodes of the capacitor. Therefore, in the case of this embodiment, the electrodes 10b1 and 10b2 embedded in the ceramic base 5a serve as both end electrodes of the capacitor of FIG.

In this case, in order to maximize the effectiveness of pattern trimming, the intermediate electrode 10a is replaced with the electrode 10b.
It is preferable to perform pattern trimming so that the facing area is evenly reduced for each of 1 and 10b2.

The electrodes of the capacitor used in the present invention are
For example, it has a structure in which nickel (Ni) and gold (Au) are plated on metallized tungsten (W), but the material and configuration are not limited to these. In particular, the electrode 10a may be any other known metal material that can be metallized to ceramic as long as it can be trimmed. For example, Mo-Mn metallization or another plating coating pattern may be used.

In the embodiment of FIGS. 1 to 3, the electrode 1
0a was placed in a dish-shaped recess 5b formed on the bottom surface of the ceramic base 5a. This is provided to prevent the electrode 10a from coming into contact with the mounting substrate when the oscillator module is mounted on the substrate.
b can also be used as a liquid sump to be dropped when a liquid resin is used when an insulating coating is carried out if necessary. However, if there is no problem in reliability in mounting on the board, the above-mentioned recess 5b can be omitted. Further, the circuit configuration of this oscillator module is not limited to the configuration shown in FIG. 4, and it goes without saying that various modified examples can be considered. For example, the oscillation circuit unit is a C-MOS
Inverters and bipolar transistors can also be used.

[0018]

As described above, when the ceramic package structure for an oscillator module according to the present invention is used, it has been used as a frequency adjusting element in the related art, and a rotary type variable capacitor or a chip type which is bulky in terms of mounting volume. Since an alternative function as a capacitor is given to a part of the package without using a trimmable capacitor, the oscillator module can be made compact. Moreover, since the structure of the package itself can be simply configured, the package cost can be reduced as compared with the conventional case. Further, the rotary type variable capacitor, the chip-shaped trimmable capacitor and the mounting process which have been used conventionally can be omitted, which is advantageous in terms of assembly cost.

[Brief description of drawings]

FIG. 1 is a sectional view showing one embodiment of a ceramic package structure for an oscillator module according to the present invention.

FIG. 2 is a cross-sectional view showing a state in which electrodes of the capacitor characterized by the present invention in FIG. 1 are pattern-trimmed.

FIG. 3 is a sectional view showing another embodiment of the present invention.

FIG. 4 is a circuit diagram showing an example of a circuit configuration of an oscillator module having a capacitance adjusting function.

FIG. 5 is a sectional view showing an example of a conventional ceramic package structure for an oscillator module.

[Explanation of symbols]

 1 Crystal oscillator 2 Semiconductor element 5 Package 5a, 6 Dimple 10 Capacitor for capacitance adjustment 10a, 10b, 10b1, 10b2 electrode Cx Variable capacitor for capacitance adjustment R Resistance Cg, Cd, Cl, C2 capacitor

Claims (3)

[Claims] 1. In an oscillator module having a function of adjusting an oscillation frequency by adjusting capacitance, an electrode arranged on an outer surface of a package and a counter electrode arranged opposite to each other with at least a part of a ceramic material of the package interposed therebetween. A ceramic package structure for an oscillator module, characterized in that a capacitor for capacitance adjustment is constituted by a ceramic material of a package arranged between these electrodes. 2. The ceramic package structure for an oscillator module according to claim 1, wherein the number of the counter electrodes is two. 3. The ceramic package structure for an oscillator module according to claim 1, wherein the counter electrode is embedded in a ceramic material of the package.