JP2021129254A - Piezoelectric device and base - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric device having a structure suitable for thinning and preventing a short circuit between a manufacturing jig and a mounting terminal. A piezoelectric device 10 has a base 11 having a recess 11a for accommodating a piezoelectric vibrating piece 13 and having a side wall around the recess, the piezoelectric vibrating piece fixed in the recess by a fixing material, and a recess. It is provided with a lid member 15 that seals the above. Then, the reinforcing portion 19 provided at the corner of the recess across the bottom surface of the recess and the side wall without contacting the piezoelectric vibrating piece, and the convex portion protruding to the outside of the part of the side wall that corresponds to the outer surface of the piezoelectric device. 21 and. The convex portion is provided so that at least a part thereof faces the reinforcing portion. [Selection diagram] Fig. 1

Description

The present invention relates to piezoelectric devices and suitable bases for use in the manufacture thereof.

In various electronic devices, piezoelectric devices such as crystal oscillators and crystal oscillators are often used for frequency selection and control.

A typical example of a crystal oscillator, which is a kind of piezoelectric device, is disclosed in, for example, Patent Document 1. 3A to 3C are views for explaining the crystal oscillator 100, FIG. 3A is a schematic plan view thereof, and FIG. 3B is a line PP in FIG. The cross-sectional view taken along the line (C) is a cross-sectional view taken along the line QQ in the figure (A).

In the crystal unit 100, a ceramic base 101 having a recess 101a is used. The crystal piece 103 is housed in the recess 101a. Specifically, the crystal piece 103 is fixed to the connection bump 101b in the recess 101a at the position of the extraction electrode 105a on one surface of the crystal piece 103 by the conductive adhesive 107. In addition, what is shown by 105b in FIG. 3A is an excitation electrode. A mounting terminal 101c is provided on the outer bottom surface of the base 101, and the mounting terminal 101c is connected to the connection bump 101b by via wiring (not shown). A flat plate-shaped lid member 109 is joined to the top surface of the side wall around the recess 101a of the base 101.

The side surface of the base 101 is a surface substantially orthogonal to the bottom surface. Further, in order to prevent a short circuit between the mounting terminals 101c when the crystal oscillator 100 is mounted on an electronic device or the like by soldering, it is preferable to widen the space between the mounting terminals 101c as much as possible, while ensuring the soldering strength. Therefore, the area of the mounting terminal 101c should be as large as possible. In order to satisfy these demands, it is preferable to effectively use the entire bottom surface of the base 101. Therefore, the ends of the mounting terminals 101c are provided as close to the edge of the bottom surface of the base 101 as possible.

Japanese Unexamined Patent Publication No. 2011-228352 (for example, FIG. 3)

With the thinning of electronic devices, the demand for thinning of crystal units is increasing more and more. In such a case, since an AT-cut crystal piece is used in a general-purpose crystal unit, the thickness of the crystal piece is determined by a required frequency, and there is a restriction in reducing the thickness of the crystal piece. It is also necessary to secure a space for applying the conductive adhesive and a space for vibration of the crystal piece. Therefore, there is a limit to making the depth of the recess 101a of the base 101 (D in FIG. 3C) shallow. Therefore, in order to reduce the thickness of the crystal oscillator, the thickness of the bottom plate of the base (FIG. 3). It is necessary to make T) in 3 (C) thinner. However, in the manufacturing process of the crystal unit, for example, the impact of the work of clamping the base by the manufacturing equipment and the stress at the time of sealing extend to the base. It will be important.

Further, as described above, in the conventional crystal unit, the side surface of the base 101 is a surface substantially orthogonal to the bottom surface, and the end portion of the mounting terminal 101c is as close as possible to the edge of the bottom surface of the base surface. Since it is provided, for example, the following problems may occur. FIG. 4A is an explanatory view thereof, and is a cross-sectional view showing a state in which the intermediate of the crystal oscillator before sealing with the lid member is put in the jig 200 used in the manufacturing process. In such a situation, for example, an intermediate body of the crystal oscillator is inserted into the jig 200 with the top and bottom reversed, and a measurement probe (not shown) is applied to the mounting terminal 101c to electrically perform the crystal oscillator. This is a scene where characteristics such as oscillation frequency and effective resistance are measured. The jig 200 is often made of metal in order to ensure its processing accuracy and durability. In such a case, the mounting terminal 101c may come into contact with the side wall of the metal jig 200, which may cause a problem that a desired electrical measurement cannot be performed.

In order to avoid this, it is conceivable to coat the jig 200 with an insulating material, but there is a risk that the coating material will peel off and become a foreign substance. When the crystal oscillator is, for example, a thick slip oscillator, it is preferable to avoid coating because even a minute foreign substance causes problems such as oscillation failure.

Further, as shown in FIG. 4B, it is conceivable to take measures to shift the mounting terminal 101c from the end portion of the bottom surface of the base 101 to the center side of the base 101 by the dimension d. However, even in such a case, the mounting terminal 101c may be located at the end of the bottom surface of the base due to pattern deviation or the like when the mounting terminal 101c is formed. If the mounting terminal 101c is designed to be further moved toward the center side of the base so that there is no problem even if the pattern shift occurs, it is not preferable because it goes against the original purpose of widening the space between the mounting terminals.
This application was made in view of these points. Therefore, the purpose of this application is a piezoelectric device having a structure suitable for thinning and preventing the mounting terminal from coming into contact with a manufacturing jig or the like. And to provide a suitable base for use in its manufacture.

To achieve this goal, the inventor of this application focused on the corners of the recesses of the base and the side walls of the base. That is, it is considered preferable to add a specific structure to each of the corner of the recess of the base and the outer surface of the side wall of the base to reduce the thickness of the piezoelectric device and prevent the mounting terminal from being short-circuited with the jig. ..
Therefore, according to the invention of the piezoelectric device of the present application, a base having a recess for accommodating the piezoelectric vibrating piece and having a side wall around the recess, and a piezoelectric vibrating piece fixed in the recess by a fixing material. In a piezoelectric device including a lid member that seals the recess.
A reinforcing portion provided across the bottom surface of the recess and the side wall without contacting the piezoelectric vibrating piece is provided at a corner of the recess.
A part of the side wall that corresponds to the outer surface of the piezoelectric device is provided with a convex portion that protrudes to the outside.

Further, according to the invention of the base of this application, in a base having a recess for accommodating the piezoelectric vibrating piece and having a side wall around the recess.
A reinforcing portion provided across the bottom surface of the recess and the side wall without contacting the piezoelectric vibrating piece to be accommodated is provided at the corner of the recess.
A part of the side wall that corresponds to the outer surface of the base is provided with a convex portion that protrudes to the outside.

In carrying out the above-mentioned inventions of the piezoelectric device and the base, the reinforcing portion is preferably an integral part of the base. Further, the reinforcing portion is preferably tapered so as to be inclined from the side wall toward the bottom surface of the recess. Further, it is preferable that a part of the reinforcing portion also serves as a pillow portion for preventing the tip portion of the piezoelectric vibrating piece from being lowered on the side opposite to the side fixed to the base.

Further, the reinforcing portion may be provided at a corner of the entire circumference of the recess, or may be provided at a part of the entire circumference instead of the entire circumference. However, in reality, the reinforcing portion is preferably provided on the entire circumference of the corner, or at least 50% or more of the entire circumference. For example, in the case of a base having a rectangular recess in a planar shape, a reinforcing portion is provided at all the corners of each side of the rectangular recess, or at least 50% of the length of each side is provided. It is preferable to provide a reinforcing portion in the portion corresponding to the above.

Further, in carrying out the inventions of the above-mentioned piezoelectric device and base, it is preferable that the convex portion is provided so that at least a part thereof faces the reinforcing portion. This is because the reinforcing portion and the convex portion together can contribute to improving the strength of the base.

According to the piezoelectric device and the base of the present invention, a predetermined reinforcing portion is provided at a corner of a concave portion of the base, and a convex portion protruding to the outside is provided at a portion of the side wall that corresponds to the outer surface of the base. There is. Since the convex part also functions as a reinforcing material, in combination with the above reinforcing part, even if the base bottom plate is thinned to such a thickness that the strength cannot be secured by simply thinning the base bottom plate, it is necessary for the crystal unit. Strength can be secured. Further, since the mounting terminal can be separated from the manufacturing jig by the convex portion, a short circuit between the mounting terminal and the manufacturing jig can be prevented.

(A) to (C) are explanatory views of the piezoelectric device 10 of the embodiment. (A) is an observation photograph of a cross section of the prototype corresponding to FIG. 1 (C), and (B) is a diagram showing a dimensional example of the prototype. (A) to (C) are explanatory views of a conventional piezoelectric device and its problems. (A) and (B) are explanatory views of other problems of the conventional piezoelectric device.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be noted that the figures used in the description are merely schematic to the extent that these inventions can be understood. Further, in each figure used for explanation, similar constituent components may be indicated with the same number, and the description thereof may be omitted. Further, the shapes, dimensions, materials and the like described in the following embodiments are merely preferable examples within the scope of the present invention. Therefore, the present invention is not limited to the following embodiments.

1. 1. Embodiments of the Piezoelectric Device and Base FIG. 1 (A) is a plan view illustrating the piezoelectric device 10 of the embodiment, and FIG. 1 (B) is along the line PP of FIG. 1 (A) of the piezoelectric device 10. A cross-sectional view, FIG. 1C is a cross-sectional view taken along the QQ line. Note that the lid members are not shown in FIGS. 1 (A) and 1 (C).
The piezoelectric device 10 of this embodiment includes a base 11, a crystal piece 13 as a piezoelectric vibrating piece 13, and a lid member 15. The piezoelectric vibrating piece 13 is, for example, an AT-cut crystal vibrating piece or an SC-cut crystal vibrating piece. The crystal piece 13 has a rectangular planar shape. The piezoelectric vibration piece 13 may be of another vibration mode such as a tuning fork type crystal vibration piece.
Excitation electrodes 13a are provided on the front and back surfaces of the piezoelectric vibrating piece 13, and the end of the piezoelectric vibrating piece 13 is a lead-out electrode 13b.

The base 11 can be made of, for example, ceramics. The base 11 includes a recess 11a having an opening wider than the planar shape of the piezoelectric vibrating piece 13, and a connection bump 11b for connecting the piezoelectric vibrating piece provided on the inner bottom surface of the recess 31a. Further, the base 11 includes a mounting terminal 11c provided on the outer bottom surface thereof, and via wiring (not shown) for connecting the mounting terminal 11c and the connection bump 11b. The plane shape of the base 11 and the recess 11a is rectangular.

The extraction electrode 13b of the piezoelectric vibrating piece 13 is connected to the connection bump 11b of the base 11 by the conductive adhesive 17, and the piezoelectric vibrating piece 13 is fixed to the base 11.
The lid member 15 is joined to the top surface of the bank portion around the recess of the base 11 by an arbitrary suitable sealing method, and the piezoelectric vibrating piece 13 is hermetically sealed.

The base 11 further includes a reinforcing portion 19 provided at a corner of the recess 11a across the bottom surface and the side wall of the recess 11a without contacting the piezoelectric vibrating piece 13. The reinforcing portion 19 of this embodiment is integrated with the base 11. However, the reinforcing portion 19 has a tapered shape that is inclined from the side wall of the recess 11a toward the bottom surface of the recess 11a. By integrating the reinforcing portion 19 with the base 11, it is easier to secure the strength of the base 11 as compared with the case where it is not. Further, by making the reinforcing portion 19 tapered, the possibility that the piezoelectric vibrating piece 13 comes into contact with the base can be reduced as compared with the case where the reinforcing portion 19 is not formed. Further, if the reinforcing portion 19 is tapered, a reinforcing portion having a triangular cross section is formed at a corner of the recess 11a. Since the triangular shape has a high reinforcing effect, it is possible to realize a reinforcing portion having relatively high strength even if the reinforcing portion is fine. The portion of the reinforcing portion 19 facing the tip end side of the piezoelectric vibrating piece 13 may function as a pillow at the tip of the piezoelectric vibrating piece 13.

The base 11 further includes a convex portion 21 protruding to the outside in a part of the side wall that corresponds to the outer surface of the piezoelectric device 10. That is, the convex portion 21 is provided in a part extending from the side surface of the bottom plate of the base 11 to the side surface of the bank surrounding the recess 11a. However, it is preferable that the convex portion 21 is provided so that at least a part of the convex portion 21 faces the reinforcing portion 19 in the concave portion 11a. This is because the reinforcing portion 19 and the convex portion 21 can work together to increase the strength of the base 11. It is preferable that the convex portion 21 is also integrally with the base 11. Further, although the shape of the convex portion 21 is trapezoidal in cross-sectional view in the illustrated example, any suitable shape may be used. The original purpose is to have a structure in which the mounting terminal 11c retracts from the tip of the convex portion 21 by projecting the convex portion 21 in the horizontal direction with respect to the edge of the bottom surface of the base 11.

The specific dimensions and taper angle of the reinforcing portion 19, and the thickness of the base 11 from the bottom surface may be determined in consideration of the size of the piezoelectric device 10, the size and thickness of the piezoelectric vibrating piece 13, and the like. Further, the size of the convex portion 21 and the protruding dimension from the side wall may be determined in consideration of the size of the piezoelectric device 10 and the like. Dimensional examples of prototypes are shown in the Examples section below.
In recent years, as a manufacturing method for a ceramic base, a manufacturing method for molding a ceramic base material using a mold has been developed, and it is easier to obtain a base having an arbitrary shape as compared with the conventional method. Therefore, the shape and size of the reinforcing portion 19 as in the present invention can also be relatively freely determined by the method using the above-mentioned mold. Further, in recent years, a manufacturing method has been established in which a large number of bases 11 are formed in a matrix in a sheet state, and then the sheets are individually scribed into individual bases 11 by scribe. Therefore, the convex portion 21 can be formed relatively easily by devising how to use the scribing means at the time of scribing.

(Example)
A so-called 0806 size base having a long side of 0.8 mm and a short side of 0.6 mm was prototyped. 2 (A) and 2 (B) are explanatory views thereof, and in particular, FIG. 2 (A) is a cross-sectional photograph of a portion of the prototype base 11x corresponding to the cross-sectional view of FIG. 1 (C), FIG. 2 (B). ) Is a diagram illustrating a dimensional example of the cross-sectional photograph portion of the prototype base 11x. In addition, in FIGS. 2A and 2B, the one shown with 11y is a metallized film for joining the lid member 15.

In the prototype base 11x, the convex portion 21 is a trapezoidal convex portion when viewed in the horizontal direction in a cross-sectional view, and the length h1 of the upper base of the trapezoid is 80 ± 5 μm, and the convex portion 21. The vertical dimensions h2 and h3 of the slope from the upper bottom are 10 ± 5 μm each, the height h4 of the side wall of the recess 11a (including the thickness of the metallized film 11y) is 80 ± 5 μm, and the thickness of the bottom plate of the base 11. h5 is 80 ± 5 μm, the depth h6 of the recess 11a is 100 ± 5 μm, the height h7 of the reinforcing portion 19 is 40 ± 5 μm, the width W1 of the side wall of the base is 60 ± 5 μm, and the protruding dimension W2 of the convex portion is 10 ±. The width W3 of the reinforcing portion is set to 5 μm and 50 ± 5 μm. Therefore, the ratio W2 / W1 of the protrusion dimension W2 of the convex portion to the width W1 of the side wall is in the range of 5/65 to 15/55 in consideration of the maximum and minimum values of each of W1 and W2. It was confirmed that in the prototype base 11x, the base strength was improved and the short circuit between the jig and the mounting terminal could be prevented as compared with the case where there was no reinforcing portion and the protruding portion.

2. Other Embodiment The structure of the reinforcing portion is not limited to the above-described embodiment, and may be, for example, the following structure.
In the case of FIG. 1, the reinforcing portion 19 is provided in the entire corner of the recess, but may be provided in the corner of the recess of the base in a discrete manner. Further, although the reinforcing portion 19 in the case of FIG. 1 is inclined obliquely from the side wall of the base to the bottom surface, it may be inclined in a plurality of steps. Further, a reinforcing portion may be provided between the two connection pads 11b so that the reinforcing portion extends.
Further, in the example of FIG. 1, the convex portions 21 are provided over the entire outer circumference of the base, but the convex portions may be provided at various places over the entire outer circumference of the base.

Further, in the above description, the embodiments of the piezoelectric device and the base of the present invention have been described, but the present invention is not limited to the above-described embodiments. For example, in the above example, a crystal oscillator has been described as an example of a piezoelectric device, but the present invention can be applied to a crystal oscillator, and further to a piezoelectric oscillator or a piezoelectric oscillator using a piezoelectric material other than crystal. .. Further, in the above-described embodiment, the number of places to be fixed with the fixing material (conductive adhesive) is set to 2, but the present invention can be applied to the case of 3 or more places. Further, in the above, an example in which the planar shape of the piezoelectric vibrating piece is rectangular is shown, but even if the planar shape is square or circular, a reinforcing portion is provided at the corner of the concave portion of the base used for the planar shape. , The present invention of providing a protruding portion on the side wall of the base can be applied.

10: Piezoelectric device of the embodiment, 11: Base of the embodiment,
11a: recess, 11b: connection bump,
11c: Mounting terminal, 13: Piezoelectric vibrating piece,
13a excitation electrode, 13b: extraction electrode,
15: Closure member, 17: Fixing material (conductive adhesive),
19: Reinforcing part, 21: Convex part

Claims (8)

A base having a recess for accommodating the piezoelectric vibrating piece and having a side wall around the recess, a piezoelectric vibrating piece fixed in the recess by a fixing material, and a lid member sealing the recess. In a piezoelectric device equipped with
A reinforcing portion provided across the bottom surface of the recess and the side wall without contacting the piezoelectric vibrating piece is provided at a corner of the recess.
A piezoelectric device, characterized in that a portion of the side wall that corresponds to the outer surface of the piezoelectric device is provided with a convex portion that protrudes to the outside. The reinforcing portion and the convex portion are integrated with the base and. The piezoelectric device according to claim 1, wherein at least a part of the convex portion is provided so as to face the reinforcing portion. The piezoelectric device according to claim 1 or 2, wherein the ratio of the protruding dimension of the convex portion to the width of the side wall is in the range of 5/65 to 15/55. The piezoelectric device according to any one of claims 1 to 3, wherein the convex portion has a trapezoidal shape in a cross-sectional view. In a base having a recess for accommodating the piezoelectric vibrating piece and having a side wall around the recess.
A reinforcing portion provided across the bottom surface of the recess and the side wall without contacting the piezoelectric vibrating piece to be accommodated is provided at the corner of the recess.
A base characterized in that a portion of the side wall corresponding to the outer surface of the base is provided with a convex portion protruding to the outside. The reinforcing portion and the convex portion are integrated with the base and. The base according to claim 5, wherein at least a part of the convex portion is provided so as to face the reinforcing portion. The base according to claim 5 or 6, wherein the ratio of the protruding dimension of the convex portion to the width of the side wall is in the range of 5/65 to 15/55. The base according to any one of claims 5 to 7, wherein the convex portion has a trapezoidal shape in a cross-sectional view.

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