JP2000124737A - Surface mounting piezoelectric oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To store a crystal piece and an integrated element in the surface and back side recesses separately and also prevent the abnormal oscillation and the variation of frequency by forming a shielding electrode on a bottom wall layer to electrically isolate a piezoelectric piece from the integrated element and eliminating a closed loop of high frequency that is formed between the input and output sides of an oscillating amplifier. SOLUTION: A shielding electrode 18 is formed on the surface of a bottom wall layer 4 and covered with an area that is equal to or wider than an exciting electrode. The electrode is connected to a mounting terminal serving as a ground electrode via an electrode through-hole 11 at the side opposite to a single extending outer circumference part of a drawer electrode. In such a constitution, the electrode patterns formed on the back sides of the integrated element and the layer 4 are electrically independent of a crystal piece via the electrode 18 that is grounded. Thus, the electrostatic or electromagnetic connection is prevented between the output terminal side of an oscillating amplifier contained in the integrated element and the exciting electrode of the crystal piece in particular that serves as the input side of the oscillating amplifier. As a result, a closed loop that is formed between the input and output sides of the oscillating amplifier can be eliminated and also the abnormal oscillation can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a surface-mounting piezoelectric oscillator (hereinafter referred to as a surface-mounting oscillator) as an industrial technical field,
In particular, the present invention relates to a surface mount oscillator in which a crystal unit (crystal unit) and an oscillation circuit are electrically disconnected.

[0002]

2. Description of the Related Art A surface-mounted oscillator comprises a crystal chip and an integrated element (IC) constituting an oscillation circuit housed in a single container. Widely used for communication equipment and digital control equipment.
As one of such devices, there is a device in which a crystal blank and an integrated element according to the present application are separately and independently housed in a container to enhance productivity (Japanese Patent Application Laid-Open No. 9-298440).

(Example of Prior Art) FIGS. 3 and 4 are views of a surface mount oscillator for explaining a conventional example, FIG. 3 is an exploded view, and FIG. 4 is a sectional view. The surface mount oscillator includes a container 1, a crystal blank 2, and an integrated element 3. The container 1 is a ceramic laminate and includes a bottom wall layer 4, a front frame layer 5, and a back frame layer 6. The bottom wall layer 4 is a flat plate and has an electrode pattern (not shown) on the back surface. The front frame layer 5 and the back frame layer 6 each have a window, thereby forming a front recess 7 and a back recess 8.

[0004] The surface frame layer 5 has two layers, and the width of the frame of the first layer 5a at one end is larger than that of the second layer 5b to form the dividing step 9 (ab). Each of the divided step portions 9 has an electrode 10 (ab), reaches the bottom wall layer 4 through an electrode through hole (so-called through hole) 11, further extends the surface, and extends to the back surface through the inter-electrode through hole 11. Then, a transducer characteristic detection terminal 12 (ab) is formed. Further, on the outer wall surface and the bottom surface of the back frame layer 6, a power source, an output,
It has a mounting terminal (not shown) such as a ground.

[0005] The crystal blank 2 has excitation electrodes on both main surfaces, and an extraction electrode extends to one end outer peripheral portion (not shown). The outer peripheral portion of one end of the crystal blank 2 is fixed to the step portion 9 of the surface frame layer 5 with a conductive adhesive, electrically and mechanically connected, and housed in the surface concave portion 7. Then, for example, the metal cover 13 is formed by seam welding.
And sealed. In this case, the welding ring 14 is soldered to the upper surface of the surface frame 5.

The integrated element 3 is formed by integrating circuit elements such as a transistor (amplifier) and a capacitor constituting an oscillation circuit. Then, they are connected to the electrode terminals 12 (ab) of the crystal blank 2 extending to the back surface concave portion 8 and each terminal of the circuit pattern, and are directly fixed, for example (commonly called face-down bonding).

In such a device, the crystal blank 2 is housed in the front recess 7 and the integrated element 3 is housed in the rear recess 8 separately and independently. Then, after the crystal blank 2 is connected to the step portion 9, the characteristics of the crystal resonator are measured by the detection terminals 12 (ab) extending to the back surface concave portion 8. Therefore, before accommodating the expensive integrated element 3, the temperature characteristic of the crystal unit is particularly selected and only good products are used, so that the yield and productivity as a surface mount oscillator are improved.

[0008]

[Problems to be Solved by the Invention]
However, in the surface mount oscillator having the above configuration, the crystal blank 2
And the integrated element 3 face each other with the bottom wall layer 4 interposed therebetween. Therefore, the output end side of the integrated element 3 including the electrode pattern and the electrode 2a of the crystal blank 2 serving as the input side of the oscillation amplifier (such as an inverter) 15 are electrostatically or electromagnetically coupled ( (See FIG. 5). FIG. 5 is a circuit diagram of the inverter oscillator, wherein C1 and C2 are oscillation capacitors, C0
Is a feedback capacitance composed of a stray capacitance.

That is, a closed loop is formed between the input and output of the oscillation amplifier 15 at a high frequency. In particular, as miniaturization progresses, the smaller the gap between the facing crystal blank 2 and the circuit pattern, the stronger the coupling. Therefore, the amount of the high-frequency signal (oscillation output) fed back from the output side of the oscillation circuit to the input side also increases, which causes a problem of causing abnormal oscillation.

Also, if there is feedback from the output side, the operating voltage including high frequencies fluctuates. Therefore, for example, when voltage control is performed by a temperature compensation oscillator or the like (see FIG. 6), the voltage VC applied to the voltage variable capacitance element (diode or the like) 16 changes. Therefore, in this case, the voltage cannot be supplied as designed, which affects temperature compensation,
There was a problem that the oscillation frequency could not be controlled stably. In addition,
In the figure, VCC is a power supply, V0 is an output, and 17 is a high-frequency blocking resistor.

Further, when a surface-mounted oscillator is mounted on a circuit board forming, for example, a mobile phone (device), there is a problem that the oscillation frequency changes due to a stray capacitance inherent in each device.

(Object of the Invention) It is an object of the present invention to provide a surface mount oscillator in which a crystal blank and an integrated element are separately housed in a concave portion on a front surface and a concave portion on a rear surface, and in which abnormal oscillation and frequency change are prevented. .

[0013]

According to the present invention, a basic solution is to form a shield electrode on a bottom wall layer for electrically intercepting a piezoelectric piece and an integrated element.

In the present invention, since the shield electrode is provided on the bottom wall layer, the piezoelectric element and the integrated element are electrically disconnected from each other.
This prevents formation of a high-frequency closed loop between the input and output of the oscillation amplifier. Hereinafter, an embodiment of the present invention will be described.

[0015]

1 and 2 are views of a surface mount oscillator for explaining an embodiment of the present invention. FIG. 1 is a plan view of a bottom wall forming a container, and FIG. FIG. 14 is a cross-sectional view taken along a line A ′. The same parts as those in the prior art are denoted by the same reference numerals, and description thereof will be omitted or simplified.

As described above, the surface-mounted oscillator has a ceramic container 1 composed of the bottom wall layer 4, the front frame layer 5 and the back frame layer 6, and is housed in the front concave portion 7 and has an outer peripheral portion at the step portion 9 at one end. Quartz piece 2 to be fixed and vibrator characteristic detecting terminal 12
(Ab) and the integrated element 3 housed in the back surface concave portion 8 to form an oscillation circuit (see FIGS. 3 and 4).

In this embodiment, a shield electrode 18 is formed on the surface of the bottom wall layer 4. The shield electrode 18 covers the excitation electrode (not shown) with an area equal to or greater than that of the excitation electrode.
Then, at the other end side in the direction opposite to the one end outer peripheral portion of the extension of the extraction electrode, it is connected to a mounting terminal serving as a ground electrode through an electrode through hole 11.

With such a configuration, the electrode patterns provided on the back surfaces of the integrated element 3 and the bottom wall layer 4 and the crystal blank 2 are
It is electrically independent by the shield electrode 18 which is grounded. Therefore, electrostatic or electromagnetic coupling between the output terminal side of the oscillation amplifier 15 incorporated in the integrated element 3 and the excitation electrode 2a of the crystal blank 2 serving as the input side is prevented (the fifth embodiment). See figure).

Therefore, since a high-frequency closed loop is not formed between the input and output of the oscillation amplifier 15, abnormal oscillation is prevented. In particular, as miniaturization progresses, the effect increases as the gap between the facing crystal blank 2 and the circuit pattern and the integrated element 3 decreases. The shield electrode 18 prevents feedback from the output side, thereby stabilizing the operation level. Therefore, for example, when voltage control is used as the temperature compensation oscillator (see FIG. 6), a change in the voltage VC applied to the voltage variable capacitance element (diode or the like) 16 is prevented, and the temperature compensation is improved.

Further, a certain stray capacitance (referred to as an oscillator internal capacitance) is generated between the shield electrode 18 and the integrated element 3 including the circuit pattern. Therefore, for example, when the device is mounted on a device such as a mobile phone, the internal capacitance of the oscillator becomes dominant, so that frequency fluctuation due to stray capacitance on the device side can be prevented.

[0022]

[Other Matters] In the above embodiment, the integrated element 3 is accommodated in the concave portion 8 on the back surface, but a chip capacitor or the like may be connected as another element. Further, although the shield electrode is formed on the surface of the bottom wall layer 4, for example, the bottom wall layer may be provided in two layers and provided in between. Further, although the metal cover is joined and sealed by seam welding, glass sealing or resin sealing with another insulating material may be used. Further, the transducer characteristic detection terminal 12 (ab) is formed on the bottom surface of the bottom wall layer 6, but has a structure in which the crystal blank 2 and the integrated element 3 are basically opposed to each other on both main surfaces of the bottom wall layer 6. Can basically be applied, and can be freely changed as appropriate without departing from the spirit of the invention.

[0023]

According to the present invention, since the shield electrode for electrically intercepting the piezoelectric piece and the integrated element is formed on the bottom wall layer, the quartz piece and the integrated element are separately housed in the front and rear recesses, respectively.
In addition, it is possible to provide a surface mount oscillator that prevents abnormal oscillation and frequency change.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an embodiment of the present invention, and is a plan view of a bottom wall layer in a surface mount oscillator.

FIG. 2 is a view for explaining an embodiment of the present invention, and is a view A of FIG. 1;
It is sectional drawing of the surface mount oscillator in -A '.

FIG. 3 is an exploded view of a container in a surface mount oscillator illustrating a conventional example.

FIG. 4 is a cross-sectional view of a surface mount oscillator illustrating a conventional example.

FIG. 5 is an oscillation circuit diagram for explaining a problem in the conventional example.

FIG. 6 is an oscillation circuit diagram for explaining a problem of the conventional example.

[Explanation of symbols]

1 container, 2 crystal pieces, 3 integrated elements, 4 bottom wall 5
Front frame layer, 6 Back frame layer, 7 Front recess, 8 Back recess, 9 steps, 10 split steps, 11 through hole, 12
Oscillator characteristic detection terminal, 13 metal cover, 14 metal ring, 15 oscillation amplifier, 16 voltage variable capacitance element (variable capacitance diode), 17 resistor, 18 shield electrode.

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Hiroshi Yoshida Inventor F-term (reference) 5J079 AA04 BA23 BA35 BA39 BA43 HA07 HA09 HA28 KA01 at 1275 Kamihirose, Sayama-shi, Saitama, Japan KA05 5J108 BB02 CC04 EE03 GG03 GG16 KK04

Claims (1)

[Claims] 1. A back surface produced by a back frame layer laminated on the other main surface side of the bottom wall layer, in which a piezoelectric piece is accommodated in a surface recess formed by a surface frame layer laminated on one main surface side of the bottom wall layer. A surface mounted piezoelectric oscillator having an integrated circuit element housed in a concave portion, wherein a shield electrode for electrically intercepting the piezoelectric piece and the integrated element is formed on the bottom wall layer. Piezoelectric oscillator.