JPH1168503A - Multi-mode crystal oscillator - Google Patents

Abstract

(57) [Summary] [Object] To provide a multi-mode vibrator in which the conduction resistance of a common electrode extraction electrode is reduced and the guaranteed attenuation is improved. In a multi-mode crystal resonator having a crystal element having an input / output electrode on one main surface and a common electrode on the other main surface, a side face of the crystal element is moved from the common electrode of the crystal element. A lead electrode extending over both main surfaces is extended to the outer periphery of the end.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an MCF (Monolithic C
The application field is a multi-mode crystal oscillator (hereinafter referred to as a multi-mode oscillator) used as a rystal filter. Especially, the direct connection by wires (so-called wire bonding) has been eliminated, and a small surface mount with an increased guaranteed attenuation. The present invention relates to a multi-mode vibrator for use.

[0002]

[Prior art]

(Background of the Invention) A multi-mode resonator is formed by acoustically coupling two resonance characteristics of a crystal resonator, has excellent transmission characteristics as compared with an LC filter or the like, and has many communications as a narrow band filter. Used in equipment. In recent years, like other elements (resistors, capacitors, and the like), surface mount type devices have been demanded, and development is in a state of competition (refer to Japanese Patent Application Laid-Open No. H8-222987).

(One Example of Prior Art) FIGS. 6 and 7 (a)
(b) is a diagram illustrating an example of this type. However, FIG. 6 is a cross-sectional view of the multimode vibrator, FIG. 7 (a) is a view of one main surface (one main surface) of the crystal blank, and FIG. 6 (b) is another main surface (other main surface). FIG. The multi-mode vibrator is made by enclosing a crystal blank 2 in a sealed container 1. The closed container 1 includes a container body 3 and a metal cover 4. The container body 3 is made of a ceramic laminate as a concave shape. The bottom surface of the container body 3 has a shield electrode 5 and a lead-out input / output electrode 6 (ab). Each of these electrodes 5 and 6 (ab) extends and is exposed on the outer surface as a surface mounting electrode (not shown). The metal cover 4 is joined to the opening surface of the container body 3 by seam welding,
Both are sealed. Reference numeral 7 in the drawing denotes a metal ring for welding.

The crystal blank 2 is made of an AT cut, and has an input / output electrode 8 (ab) on one main surface and a common electrode 9 on the other main surface. From the input / output electrode 8 (ab), the input / output extraction electrode 10 (ab) extends to both opposite corners of both ends of the crystal blank 2 in the X-axis direction of the crystal axis (XYZ). From the common electrode 9, a common extraction electrode 11 (ab) extends to the center on both ends in the Z'-axis direction. The extraction electrode 1
0 and 11 have chromium and silver as main components.

[0005] One main surface of the crystal blank 2 faces the bottom surface of the container body 3, that is, the input / output electrode 8 (ab) and the shield electrode 5 face each other. The two corners of the crystal blank 2 are fixed (held) by a conductive adhesive 12 to the lead-out input / output electrode 6 (ab), and are electrically and mechanically connected. The common extraction electrode 11 (ab) at the center end is electrically connected to the shield electrode 5 by a gold wire 13 formed by wire bonding. The metal cover 4 and the shield electrode 5 are electrically connected to each other by a through-electrode hole (so-called through hole) formed in the side wall of the container body 3.

In such a device, since the input / output electrode 8 (ab) of the crystal blank 2 and the shield electrode 5 face each other, electrical coupling between the input / output electrode 8 (ab) is prevented. Also, the shield electrode 5 is connected to the common lead electrode 11 (ab) from two places near the common electrode 9 by a gold wire 13. Therefore, the guaranteed attenuation can be increased by making the conduction resistance between the two almost zero, that is, minimizing the potential difference.

[0007]

[Problem to be Solved by the Invention]

(Problems of the prior art) However, in the multi-mode vibrator having the above configuration, the common extraction electrode 11 and the shield electrode 5 are connected by wire bonding of the gold wire 13. For this reason, when the frequency band becomes higher, for example, 40 MHz
When it exceeds z, the thickness of the crystal blank 2 also decreases (about 40
μ or less), which sometimes caused breakage during wire bonding. In addition, as the miniaturization of the multi-mode vibrator further progresses, the internal volume of the multi-mode vibrator also decreases, and a situation has arisen in which wire bonding cannot be adopted.

Therefore, it has been considered that the common extraction electrode 11 is folded back to the other main surface side and fixedly connected to the shield electrode 5 with the conductive adhesive 12 (not shown). However, in this case, the central portion of the crystal blank 2 is suppressed, and the vibration characteristics are degraded.

For this reason, as shown in FIG. 8, it is conceivable that the common extraction electrode 11 is extended to the outer peripheral portions of the opposite ends and fixed to the shield electrode 5. That is, the common extraction electrode 11 first has a length d2 smaller than the length d1 of the common electrode 9 in the X-axis direction as before, and extends to the center end.
Next, along the X-axis direction edge, the width in the Z′-axis direction is set to W1.
And extend to the outer periphery of both ends. The common extraction electrode 1
The length d2 of 1 (ab) in the X-axis direction is set to be equal to or longer than the length for ensuring electrical conduction.

However, in this case, when the size of the multi-mode vibrator is reduced, the width W1 of the crystal blank 2 in the Z′-axis direction is also reduced. Therefore, even if the common extraction electrode 11 is extended from the common electrode 9 as the length d2 in the X-axis direction for ensuring electrical conduction, the width W2 in the Z′-axis direction is equal to the length d2 in the X-axis direction.
Smaller than. From this, the common extraction electrode 11
However, there is a problem that the absolute width W2 becomes smaller, the conduction resistance becomes larger, and the guaranteed attenuation decreases.

For example, when the width W1 of the crystal blank 2 in the Z'-axis direction becomes, for example, 1.7 mm, the width W2 of the common electrode 9 becomes approximately 1 mm.
mm, the width W2 of the common extraction electrode 11 can be only about 0.3 mm, which increases the conduction resistance and lowers the guaranteed attenuation. Note that the conduction resistance can be minimized if the length d2 in the X-axis direction extending from the common electrode 9 is about 0.6 mm or more. However, in the case of a certain thickness mainly composed of chromium and silver, it is not universal and the value changes when the electrode material changes.

Further, as shown in FIG.
To the common extraction electrode 11 (ab)
It is conceivable that the conduction resistance is reduced by extending the width W2 to the maximum. However, in this case, the electrical opposing area between the input / output electrode 8 (ab) and the common electrode 9 increases, so that it is necessary to change the transmission characteristics and review the existing design.

That is, the common electrode 9 and the common extraction electrode 1
As the electrical facing area at the boundary portion of 1 increases, the theoretical electrical equivalent constants (equivalent inductance, equivalent series capacitance, and equivalent parallel capacitance) change. Therefore, the transmission characteristics change, and the existing design is reviewed.

(Object of the Invention) It is an object of the present invention to provide a multi-mode vibrator in which the conduction resistance of a common electrode lead electrode is reduced to improve the guaranteed attenuation.

[0015]

According to the present invention, there is provided a fundamental solution to the present invention in that an extraction electrode extending from a common electrode of a crystal piece to both main surfaces via side surfaces extends to the outer periphery of an end.

[0016]

In the present invention, since the common extraction electrode is formed over both main surfaces of the crystal blank, there is an effect of increasing the width thereof. Hereinafter, an embodiment of the present invention will be described.

[0017]

1 and 2 are views for explaining an embodiment of the present invention. FIG. 1 is a view of a crystal piece of a multi-mode vibrator, and FIG. 2 is a view AA 'of FIG. It is sectional drawing. In FIG. 1, the input / output electrodes are omitted. Also, the same parts as those in the prior art example are denoted by the same reference numerals, and description thereof will be simplified. As described above, the multi-mode vibrator includes the container body 3 and the metal cover 4, and has the input / output electrodes 8 (ab) and the input / output One main surface of the crystal blank 2 on which the extraction electrode 10 (ab) is formed is opposed to the bottom surface of the container body 3, and both corners on which the input / output extraction electrode 10 (ab) extends are conductively bonded to the container bottom surface. It is fixed by the agent 12 and sealed (see FIG. 6).

In this embodiment, the common extraction electrode 11 of the crystal blank 2 first has a length in the X-axis direction from the common electrode 9 of d1.
And extends to the center ends of both long sides. Next, it is formed over both main surfaces via the side surfaces of the crystal blank 2, and Z ′ is respectively formed.
It extends to the diagonal part of the outer peripheral part of both ends with the width in the axial direction being W2. Then, it is electrically connected to and fixed to the shield electrode 5 by a conductive adhesive (not shown).

The dimensions in this embodiment are as described above. The widths W1, W2 and W3 of the crystal blank 2, the common extraction electrode (one main surface) and the common electrode in the Z'-axis direction are respectively About 1.7mm, 0.3mm (0.6m in total of both main surfaces)
m) and 1 mm. The lengths d1, d2, d of the common electrode 9, the common extraction electrode 11, and the crystal blank 2 in the X-axis direction.
3 are 1 mm, 0.6 mm and 3.7 mm, respectively. Note that the total width of the common extraction electrode 9 in the Z′-axis direction includes:
A thickness dimension in the Y′-axis direction is also added.
If it is greater than z, the thickness becomes about 40 μ or less as described above, and can be generally ignored.

FIG. 3 shows the guaranteed attenuation of the “curve (a)” when the common extraction electrode 11 is formed only on the other main surface and the “curve (loha)” when the common extraction electrode 11 is formed on both main surfaces according to the present embodiment. It is a figure which compares quantity. However, the guaranteed attenuation is a value at an image frequency lowered by 910 KHz from the center frequency f0,
The center frequency is 130 MHz (third overtone). As is clear from this figure, the guaranteed attenuation amount when the common extraction electrode 11 is formed only on the other main surface “curve (a)”
Is about 70 dB without poles. On the other hand, in the case of the present embodiment, a guaranteed attenuation amount of about 90 dB "curve (b)" with poles or about 80 dB "same (c)" without poles was obtained.

By the way, in the conventional wire bonding of the gold wire 13, as in the case of the curve (b), the poles are formed and become about 90 dB. When the conduction resistance is 0, a pole is theoretically generated. Also in the case of this embodiment, depending on the amount of the conductive adhesive 12 applied, the conduction resistance varies, and in some cases, the poles do not occur and remain at 80 dB. I got it.

As described above, in this embodiment, since the common extraction electrode 11 is formed on both main surfaces via the side surfaces, even if the width of the crystal blank 2 becomes small (about 1.7 mm or less). However, the width W2 of the common extraction electrode 11 can be made sufficiently larger than d2, and an increase in conduction resistance can be prevented, so that the guaranteed attenuation can be improved. In the case of this embodiment, the MCF used for a cellular phone or the like exceeds the standard of 70 dB or more by 10 dB or more, so that it can be sufficiently put to practical use.

The common extraction electrode 11 has a length d2 in the X-axis direction smaller than that of the common electrode 9 (d1) and has the same value as the conventional one, so that the common extraction electrode 11 has the same value as the input / output electrode 8 (ab). Maintaining a constant electrical facing area with the electrode, basically,
You can follow the existing design as it is. Therefore, in the case of the same specifications as the conventional one, it is easy to change to this embodiment. Further, even if the specification is new, the input / output electrode 8 (a
Since the electrically opposed area between the b) and the common electrode 9 can be close to the theory, the design is facilitated.

[0024]

[Other Matters] In the above embodiment, the multi-mode vibrator in which the crystal blank 2 is sealed in the sealed container 1 having the shield electrode 5 on the bottom surface has been described. The crystal piece 2 having the common extraction electrode 11 (ab), the common electrode 9 and the common extraction electrode 11
The conduction resistance between the extension end of (ab) can be reduced. Therefore, the common extraction electrode 11 (ab) only needs to be connected to the ground electrode, and the multi-mode vibrator constituted by using such a crystal blank 2 regardless of the form of the closed vessel 1 is an essential element of the present invention. Effect. Further, the common extraction electrode 11 (ab) extends from both ends of the common electrode 9 in the opposite direction, but the same applies to the case where the common extraction electrode 11 (ab) is one end of the outer periphery 11a.

The common extraction electrode 11 is formed over both main surfaces through all side surfaces of the crystal blank 2. For example, as shown in FIG. 4, the common extraction electrode 11 on both main surfaces is connected to the crystal blank. Alternatively, the connection may be made only at the side surface of the center end portion of the two, and the extended end portions of both main surfaces may be connected by the conductive adhesive 12 at the time of fixing (FIG. 5). FIG. 5 is BB ′ of FIG.
FIG.

In the above embodiment, an advantage in design is given. For example, the width of the crystal blank 2 is further reduced, and as shown in FIG.
Even when the common extraction electrode 11 and the common extraction electrode 11 are adjacent to each other, the same effect can be obtained by reducing the conduction resistance across the common extraction electrode 9 to the other main surface. The conductive adhesive 12 may be, for example, cream solder or the like.
Any electrical bonding material that can be mechanically connected may be used.

As described above, the present invention can be variously modified without departing from the spirit of the present invention, irrespective of the above embodiment, and these are not excluded from the technical scope of the present invention. In short, the extension of the common extraction electrode 11 formed on both main surfaces in order to reduce the conduction resistance and improve the guaranteed attenuation belongs to the technical scope of the present invention.

[0028]

According to the present invention, since the extraction electrode extending from the common electrode of the crystal element to both main surfaces via the side surfaces is extended to the outer peripheral end of the crystal element, the conduction resistance of the extraction electrode for the common electrode is reduced. It is possible to provide a multi-mode vibrator that improves the guaranteed attenuation.

[Brief description of the drawings]

FIG. 1 is a diagram of a multi-mode vibrator, particularly a crystal blank, for explaining an embodiment of the present invention.

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

FIG. 3 is a damping characteristic diagram for explaining the operation of one embodiment of the present invention.

FIG. 4 is a partial view of a multi-mode vibrator, particularly a crystal blank, for explaining another embodiment of the present invention.

5 illustrates another embodiment of the present invention, FIG.
It is B 'sectional drawing.

FIG. 6 is a cross-sectional view of a multimode vibrator for explaining a conventional example.

FIGS. 7A and 7B are views of a multimode vibrator for explaining a conventional example, wherein FIG. 7A is a main surface view of a crystal blank, and FIG.

FIG. 8 is a view of a multi-mode vibrator for explaining a conventional example, and is a view of another main surface of a crystal blank.

FIG. 9 is a diagram of a multi-mode vibrator for explaining a conventional example, and is a diagram of another main surface of a crystal piece.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Closed container, 2 crystal piece, 3 container body, 4 metal cover, 5 shield electrode, 6 lead-in / out electrode, 7
Metal ring, 8 (ab) input / output electrode, 9 common electrode,
10 (ab) input / output lead electrode, 11 (ab) common lead electrode, 12 conductive adhesive.

Claims (3)

[Claims] 1. A multi-mode crystal resonator comprising a crystal element having an input / output electrode on one main surface and a common electrode on the other main surface. A multi-mode crystal resonator, wherein an extraction electrode extending over both main surfaces via a side surface is extended to an outer periphery of an end portion. 2. A multi-mode crystal resonator according to claim 1, wherein the crystal piece faces the substrate and is electrically connected to a ground electrode of the insulating substrate. 3. The insulating substrate according to claim 2, wherein a shield electrode facing an input / output electrode formed on one main surface of the crystal blank is formed on the insulating substrate, and a main electrode of the insulating substrate and one of the crystal blanks is formed. A multi-mode crystal resonator, wherein a surface of the crystal piece faces and an outer peripheral end of a lead electrode extending from a common electrode of the crystal piece and a shield electrode are connected by a conductive bonding material.