JP7170549B2 - Crystal element and crystal device - Google Patents

Description

The present invention relates to a crystal element and a crystal device using the crystal element.

The crystal element has a crystal blank on which a metal pattern consisting of a pair of excitation electrodes and a pair of connection lead portions is formed. Such a crystal piece has a rectangular shape with four straight sides when viewed from above (see, for example, Patent Document 1).

JP 2017-85385 A

In the crystal element, when an alternating voltage is applied to the metal pattern consisting of the connection electrode portion and the connection lead portion, thickness-shear vibration, which is the main vibration, occurs in the portion sandwiched between the excitation electrodes. Contour vibration, which is vibration, occurs. In addition, the thickness-shear vibration, which is the main vibration, leaks and propagates from the portion sandwiched between the excitation electrodes, and the vibration is reflected at the edge of the crystal piece. In this way, the contour vibration, which is a secondary vibration, and the vibration that is leak-propagated from the excitation electrode and reflected at the edge of the crystal element is called spurious vibration. Since the crystal element described above uses a crystal blank that is rectangular in plan view, the main vibration is the contour vibration that depends on the outer dimensions of the crystal blank and the vibration that is leak-propagated and reflected at the edge of the crystal blank. The influence on thickness-shear vibration increases, and there is a risk that the electrical characteristics may deteriorate.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a crystal element and a crystal device capable of improving electrical characteristics.

A crystal piece that is substantially rectangular in plan view, excitation electrode portions provided on both main surfaces of the crystal piece, and connection leads extending from the excitation electrode portion to one short side of the crystal piece. and projections located at both ends of the other short side of the crystal piece and protruding outward from a side surface that includes the other short side and connects the two principal surfaces, when viewed from above The length of one short side is shorter than the length of the other short side, and a part of the convex portion has a concave portion .

According to the above configuration, it is possible to obtain a crystal element and a crystal device with improved electrical characteristics.

1 is a perspective view of a crystal resonator that is an example of a crystal device according to an embodiment; FIG. FIG. 2 is a cross-sectional view taken along line AA of FIG. 1; FIG. 2 is a plan view of the upper surface of the crystal piece used in the crystal element according to the present embodiment; (a) is a plan view of the upper surface of the crystal element according to the present embodiment, and (b) is a plan view of the lower surface of the crystal element according to the present embodiment as seen through from the upper surface. 1 is a perspective view of a crystal element according to this embodiment; FIG. It is the top view which planarly viewed the side surface containing the other short side of the crystal element which concerns on this embodiment. It is the top view which planarly viewed the side surface containing one short side of the crystal element which concerns on this embodiment. FIG. 2 is a state diagram showing a state in which the crystal element according to the embodiment is mounted on a base;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. The drawings used in the following description are schematic, and the dimensional ratios and the like on the drawings do not necessarily match the actual ones.

(Outline description of crystal device)
1 and 2 are drawings related to a crystal oscillator, which is an example of a crystal device according to an embodiment of the present invention. 3 to 7 are drawings relating to crystal elements in embodiments of the present invention. FIG. 8 is a state diagram showing a state in which the crystal element according to this embodiment is mounted on a substrate.

A crystal oscillator is, for example, an electronic component that has a generally thin rectangular parallelepiped shape as a whole, and its dimensions may be set as appropriate. For example, the length of the long side or short side is 0.6 mm to 7.5 mm, and the thickness is 0.2 mm to 1.2 mm. A relatively small one has a long or short side length of 0.6 mm to 3.2 mm and a thickness of 0.2 mm to 0.8 mm.

The crystal oscillator has, for example, a base 110 having a recess, a crystal element 120 housed in the recess, and a lid 130 closing the recess. The recess is sealed with a lid 130, and the interior thereof is, for example, evacuated or filled with a suitable gas (eg, nitrogen).

The substrate 110 has a substrate portion 110a serving as the main body of the substrate 110, mounting pads 111 for mounting the crystal element 120, and external terminals 112 for mounting the crystal oscillator on a circuit board or the like (not shown). is doing. The substrate portion 110 a has conductors (not shown) for electrically connecting the mounting pads 111 and two predetermined external terminals 112 . A conductor (not shown) is provided on the surface and/or inside the substrate 110 . The base 110 has, for example, a frame-shaped frame portion 110b for forming a recess in the base 110 . The frame portion 110b is provided along the edge of the upper surface of the substrate portion 110a. The substrate portion 110a and the frame portion 110b forming the base 110 are made of an insulating material such as ceramic, and the mounting pads 111 and the external terminals 112 are made of a conductive layer made of metal or the like, for example.

The lid 130 is made of metal, for example, and is joined to the upper surface of the base 110 by seam welding or the like.

The crystal element 120 has a crystal piece 121 and a pair of metal patterns 122 provided on the crystal piece 121 .

The crystal piece 121 is a so-called AT-cut crystal piece. That is, in crystal, an orthogonal coordinate system XYZ consisting of an X axis (electrical axis), a Y axis (mechanical axis) and a Z axis (optical axis) is rotated around the X axis by, for example, 30° to 45° (35° as an example). °15') When an orthogonal coordinate system XY'Z' is defined by rotation, the cut angle is the same as that of a plate cut out parallel to the XZ' plane. Therefore, the crystal piece 121 has a pair of main surfaces parallel to the XZ' plane.

The crystal element 120 has a crystal piece 121 and a pair of metal patterns 122 provided on the crystal piece 121 . The metal pattern 122 is composed of a pair of excitation electrode portions 123 for applying a voltage to the crystal blank 121 and a pair of connection lead portions 124 for mounting the crystal element 120 on the mounting pads 111 .

The excitation electrode portions 123 form a pair, and are provided, for example, on the central side of both main surfaces of the crystal piece 121 (that is, away from the outer edges of both main surfaces of the crystal piece 121).

The pair of connection lead-out portions 124 is composed of a connection portion 124a and a lead-out portion 124b. Two connecting portions 124 a are provided side by side along one short edge of the crystal piece 121 , for example. The lead-out portion 124b is for electrically connecting the excitation electrode portion 123 and the connection portion 124a, and has one end connected to the excitation electrode portion 123 and the other end connected to the connection portion 124a. The lead-out portion 124b is provided, for example, so as to be parallel to the long side of the crystal piece 121 . If the excitation electrode portion 123 and the connection portion 124a can be electrically connected, the lead portion 124b extends from the excitation electrode portion 123 toward the long side of the crystal piece 121 and extends along the long side of the crystal piece 121. It may extend along the edge to the connecting portion 124a.

The crystal element 120 is housed in, for example, a recess of the base 110 with the main surface of the crystal piece 121 facing the upper surface of the substrate portion 110a of the base 110 . The connection portion 124 a of the connection lead-out portion 124 is joined to the mounting pad 111 of the base 110 by the conductive member 140 . Thereby, the crystal element 120 is supported by the substrate portion 110a of the base 110 like a cantilever beam. At this time, the connection portion 124a of the connection lead-out portion 124 and the mounting pad 111 of the base 110 are electrically connected. Therefore, the pair of excitation electrode portions 123 are electrically connected to the connection lead portion 124 , the conductive member 140 and the mounting pad 111 , and further electrically connected to any two of the plurality of external terminals 114 . The conductive member 140 is made of, for example, a conductive adhesive.

The crystal oscillator is mounted on the circuit board by, for example, placing the lower surface of the base 110 facing the mounting surface of the circuit board (not shown), and bonding the external terminals 112 to the pads of the circuit board by soldering or the like. be. For example, an oscillation circuit is configured on the circuit board. The oscillation circuit applies an alternating voltage to the pair of excitation electrode portions 123 via the external terminal 112 and the mounting pad 111 to generate an oscillation signal. At this time, the oscillation circuit utilizes, for example, the fundamental vibration among the thickness-shear vibrations of the crystal piece 121 .

(Outline explanation of the crystal element)
FIG. 3 is a plan view of a crystal piece used in the crystal element according to this embodiment. FIG. 4 is a plan view of the crystal element according to this embodiment, and FIG. 5 is a perspective view of the crystal element according to this embodiment. FIG. 6 is a side view including the other short side of the crystal element according to this embodiment, and FIG. 7 is a side view including one short side of the crystal element according to this embodiment. FIG. 8 is a state diagram showing a state when the crystal element according to this embodiment is mounted on a substrate. The crystal element 120 is composed of a crystal piece 121 and a metal pattern 122, as shown in FIGS.

(Detailed description of the crystal piece)
As shown in FIGS. 3(a) and 3(b), the crystal piece 121 is generally rectangular with its longitudinal direction being the X-axis direction. The crystal piece 121 has a pair of short sides t1 and t2 facing each other in the X-axis direction (parallel to the direction perpendicular to the X-axis). Further, the crystal piece 121 has a pair of long sides (extending between the pair of short sides) connecting the ends of the pair of short sides t1 and t2. Strictly speaking, the term "side" means a straight line, but in this embodiment, for the sake of convenience, it may be other than a straight line.

One short side t1 of the pair of short sides t1 and t2 is the short side located on the +X-axis side, which is the crystal axis of the crystal, when the crystal piece 121 is viewed from above, and the other short side t2 is It is the short side located on the -X axis side, which is the crystal axis of quartz crystal.

Here, the length of one short side t1 perpendicular to the X-axis is defined as a first distance dt1, and the length of the other short side t2 perpendicular to the X-axis is defined as a second distance dt2. The second distance dt2 is the distance from the point where one end of the other short side t2 intersects one long side to the point where the other end of the other short side t2 intersects the other long side. Say things.

In the crystal piece 121, the first distance dt1 is shorter than the second distance dt2. In other words, the length of one short side t1 (perpendicular to the X axis) is shorter than the length of the other short side t2 (perpendicular to the X axis).

The crystal piece 121 is arranged on the long side of the crystal piece 121 in a plan view so that the length of the crystal piece 121 changes in the direction parallel to the short sides t1 and t2 of the crystal piece 121 (perpendicular to the X-axis). It has an inflection point P. At this time, the length of one short side t1 of the crystal piece 121 and the inflection point P in the direction parallel to the long side of the crystal piece 121 (in the direction parallel to the X-axis) is the length of the crystal piece 121. 5% or more and 20% or less.

Here, the length in the direction parallel to the long side of the crystal piece 121 (in the direction parallel to the X-axis) between one short side t1 of the crystal piece 121 and the inflection point P is defined as the inflection point distance dp. . Also, the length of the long side of the crystal piece 121 (the length of one short side t1 of the crystal piece 121 and the other short side t2 of the crystal piece 121 parallel to the X-axis) is defined as the length dl of the crystal piece 121. do.

Therefore, the inflection point distance dp and the length dl of the crystal blank 121 have the following relationship.
0.05×dl≦dp≦0.20×dl

The crystal piece 121 has projections 125 at both ends of the other short side t2. From another point of view, when the crystal piece 121 is viewed from above, projections protrude from both ends of the crystal piece 121 in the -X-axis direction.

When the side surface of the crystal piece 121 including the other short side t2 of the crystal piece 121 provided with the convex portion 125 is viewed in plan, as shown in FIG. there is

The recess K is composed of, for example, a first recess K1, a second recess K2 and a third recess K3. The first concave portion K1 is provided on one end side of the short side t2 of the crystal piece 121 so as to be continuous with the lower surface of the crystal piece 121, as shown in FIG. The second concave portion K2 is provided on the other end side of the short side t2 of the crystal piece 121 so as to be continuous with the lower surface of the crystal piece 121, as shown in FIG. As shown in FIG. 6, the third recess K3 is provided so as to pass through the middle point of the other short side t2 of the crystal blank 121 and continue to the upper and lower surfaces of the crystal blank 121 .

Various dimensions of the crystal piece 121 may be appropriately set. For example, the length dl (X-axis direction) of the crystal blank 121 is 0.4 mm to 7.2 mm, and the length dt2 of the other short side t2 of the crystal blank 121 is 0.3 mm to 5.0 mm. ing.

(Detailed description of metal pattern)
4(a) is a plan view of the upper surface of the crystal element 120 according to the present embodiment, and FIG. 4(b) is a plan perspective view of the lower surface of the crystal element 120 according to the present embodiment. It is a top view when it does. FIG. 5 is a perspective view of the crystal element 120 according to this embodiment.

The connection lead-out portion 124 is composed of the connection portion 124a and the lead-out portion 124b as described above.

The connecting portions 124 a are provided on both ends of one short side t<b>1 of the crystal piece 121 and extend over the upper surface, the lower surface and the side surface of the crystal piece 121 . At this time, the length du of the connection portion 124a provided on the upper surface of the crystal piece 121 (from one short side t1 of the crystal piece 121 when the upper surface of the crystal element 120 is viewed in plan to the other short side of the crystal piece 121 is The length parallel to the X-axis to the side of the connection portion 124a facing the t2 side) is the length dd of the connection portion 124a provided on the bottom surface of the crystal piece 121 (the length dd when the bottom surface of the crystal element 120 is viewed in plan). length parallel to the X-axis from one short side t1 of the crystal piece 121 to the side of the connecting portion 124a facing the other short side t2 of the crystal piece 121).

4(a) and 4(b), the connecting portion 124a is provided so as to overlap the inflection point P located on the long side of the crystal blank 121. As shown in FIGS. Therefore, when the crystal element 120 is mounted on the base 110 using the conductive member 140, the conductive member 140 is in contact with the inflection point P as shown in FIG.

Further, as shown in FIG. 8, the connection portion 124a is provided so as to straddle both ends of one short side t1 of the crystal piece 121 when the side surface including the one short side t1 of the crystal piece 121 is viewed in plan. there is

(About the vibration generated by the crystal element)
When an alternating voltage is applied to the excitation electrode portions 123 of the crystal element 120 , thickness-shear vibration of the fundamental wave occurs in the portion sandwiched between the pair of excitation electrode portions 123 . The thickness-shear vibration of the fundamental wave generated at the portion sandwiched between the pair of excitation electrode portions 123 is the main vibration.

At this time, the main vibration leaks and propagates from the excitation electrode portion 123 toward the outer edge of the crystal piece 121 in plan view. Vibration generated in the direction from the excitation electrode portion 123 toward the outer edge of the crystal element 121 is referred to as leakage vibration. When the leakage vibration reaches the outer edge of the crystal piece 121 , the leakage vibration is reflected on the side surface of the crystal piece 121 and causes vibration in the direction from the outer edge of the crystal piece 121 toward the excitation electrode portion 123 . The vibration reflected by the side surface of the crystal piece 121 is referred to as reflected vibration.

Further, when an alternating voltage is applied to the excitation electrode portion 123 of the crystal element 120, not only the main vibration but also the contour vibration, which is a secondary vibration, occurs. The contour vibration depends on the length of the crystal piece 121 (the length parallel to the X-axis and the length parallel to the Z'-axis).

As described above, the crystal device according to this embodiment utilizes the thickness-shear vibration (principal vibration) of the fundamental wave generated in the crystal blank 121 . Therefore, in the crystal element 120 and the crystal device, when an alternating voltage is applied to the excitation electrode portion 123, the main vibration is used in a state in which the main vibration is influenced by the reflection vibration and the contour vibration, which are other vibrations. It can be said.

As described above, the crystal element 120 according to the present embodiment includes the crystal piece 121 which is substantially rectangular in plan view, the excitation electrode portions 123 provided on both main surfaces of the crystal piece 121, and the excitation electrodes a connection lead portion 124 extending from the portion 123 to one short side t1 of the crystal piece 121, and convex portions 125 provided at both ends of the other short side t2 of the crystal piece 121 In plan view, the length of one short side t1 (first distance dt1) of crystal piece 121 is shorter than the length of the other short side t2 of crystal piece 121 (second distance dt2).

In this way, by making the length of one short side t1 (first distance dt1) of crystal blank 121 shorter than the length of the other short side t2 of crystal blank 121 (second distance dt2), crystal blank 121 It is possible to disperse the frequency of the contour vibration, which is dependent on the length of . As a result, it is possible to reduce the deterioration of the electrical characteristics of the crystal element 120 due to the coupling of the main vibration and the contour vibration.

Further, by providing the projections 125 at both ends of the short side t2 of the crystal blank 121, it is possible to disperse the frequency of the contour vibration that depends on the length of the crystal blank 121. FIG. By doing so, the distance between the edge of the excitation electrode portion 123 and the end of the long side of the crystal piece 121 on the other short side t2 side of the crystal piece 121 and the outer edge of the excitation electrode portion 123 is can be made longer than before. Therefore, it is possible to reduce the influence of the reflected vibration generated at the end of the long side of the crystal piece 121 on the other short side t2 side of the crystal piece 121 on the main vibration, and the electrical characteristics of the crystal element 120 are reduced. It is possible to reduce the

Therefore, by adopting such a configuration, it is possible to reduce the influence of the contour vibration, which is a secondary vibration, and the reflected vibration at the outer edge of the crystal element 121 on the main vibration. can be reduced.

In addition, the crystal element 120 according to the present embodiment has an inflection point P on the long side of the crystal piece 121 in plan view, at which the length of the crystal piece 121 changes parallel to the short side of the crystal piece 121 . , the length of the inflection point P and one short side t1 of the crystal piece 121 in the direction parallel to the long side of the crystal piece 121 (the direction parallel to the X-axis), and the inflection point length dp is It is 5% or more and 20% or less of the length dl of 121.

If the inflection point length dp is shorter than 5% of the length dl of the crystal blank 121, secondary vibration occurs at the edge of one short side t1 of the crystal blank 121 where the connecting portions 124a are arranged side by side. It becomes difficult to disperse the frequency of the contour vibration, and the electrical characteristics of the crystal element 120 may deteriorate. If the inflection point length dp is longer than 20% of the length dl of the crystal piece 121, the distance between the excitation electrode portion 123 and the inflection point distance P becomes short when the crystal element 120 is viewed from above. In a part of the long side of the crystal piece 121 that includes the end of one short side t1 of the piece 121 and the inflection point P, the reflected vibration affects the main vibration, and the electrical characteristics of the crystal element 120 are changed to There is a risk that it will drop.

Therefore, by providing the inflection point P on the long side of the crystal piece 121 and limiting the position of the inflection point P, the secondary vibrations such as the contour vibration and the reflected vibration are applied to the main vibration. The influence can be reduced, and as a result, deterioration of the electrical characteristics of the crystal element 120 can be reduced.

Further, in the crystal element 120 according to the present embodiment, when the side surface including the other short side t2 of the crystal piece 121 is viewed in cross section, the recess K is formed in the side surface including the other short side t2 of the crystal piece 121. ing.

By forming the concave portion K in the side surface including the other short side t2 of the crystal piece 121 in this manner, the length of the other short side t2 of the crystal piece 121 can be partially changed. Therefore, the secondary contour vibration frequency generated near the other short side t2 of the crystal element 121 can be dispersed, and deterioration of the electrical characteristics of the crystal element 120 can be reduced.

In particular, by forming the first concave portion 125a and the second concave portion 125b in the convex portion 125 as well, it is possible to disperse the leakage vibration and the reflected vibration, thereby reducing the influence of the reflected vibration on the main vibration. . As a result, deterioration of the electrical characteristics of the crystal element 120 can be reduced.

In addition, the crystal device according to the present embodiment includes the crystal element 120 as described above and a substrate portion 110a having a mounting pad provided on the upper surface for electrically connecting a part of the connection lead portion 124 of the crystal element 120. a lid body 130 that is joined to the base body 110 and hermetically seals the crystal element 120; ,have.

By using the crystal element 120 capable of reducing deterioration of the electrical characteristics in the crystal device, the electrical characteristics of the crystal device can be improved.

Further, in the crystal device according to this embodiment, the conductive member 140 is in contact with the inflection point P when the crystal element 120 is mounted on the base 110 .

By doing so, when the conductive member 140 electrically connects and adheres the crystal element 120 and the base 110, the force that the conductive member 140 pulls on the crystal element 120 can be dispersed. The influence of 140 on the main vibration can be reduced. As a result, it becomes possible to improve the electrical characteristics of the crystal device.

The present invention is not limited to the embodiments described above, and may be embodied in various forms.

Crystal devices are not limited to crystal oscillators. For example, the crystal device may be an oscillator that includes a portion that serves as a crystal oscillator and a portion that serves as an oscillation circuit. In addition to crystal elements, crystal oscillators may also include other electronic components such as thermistors, diodes, or transistors.

The crystal element may have a mesa shape with a thick central portion instead of a flat plate shape.

The excitation electrode may have a circular or elliptical shape instead of a substantially rectangular shape.

The connection lead-out portion does not have to extend linearly along the X-axis direction. good.

REFERENCE SIGNS LIST 110 Base 110a Substrate 110b Frame 111 Mounting pad 112 External terminal 120 Crystal element 121 Crystal piece 122 Metal pattern 123 Excitation electrode portion 124 Connection lead portion 124a Connection portion 124b Lead portion 125 Convex portion 130 Lid 140 Conductive member K Concave portion K1 First concave portion K2 Second concave portion K3 Third concave portion t1 One short side t2 of crystal piece Other short side P of crystal piece Inflection point dt1 First distance (length of one short side of crystal piece)
dt2 Second distance (length of the other short side of the crystal piece)
dp: inflection point distance (length parallel to the X-axis from one short side of the crystal piece to the inflection point)
dl Length of crystal blank (length parallel to one short side of crystal blank, the other short side of crystal blank, and X-axis)
du --- length of the connection part provided on the top surface of the crystal blank parallel to the X-axis dd --- length of the connection part provided on the bottom surface of the crystal blank parallel to the X-axis

Claims (5)

a crystal piece that is substantially rectangular in plan view;
excitation electrode portions provided on both main surfaces of the crystal piece;
a connection lead portion extending from the excitation electrode portion to one short side of the crystal piece;
projections located at both ends of the other short side of the crystal piece and protruding outward from a side surface that includes the other short side and connects the two principal surfaces ;
has
In plan view, the length of the one short side is shorter than the length of the other short side ,
A part of the protrusion has a recess
A crystal element characterized by: The crystal element according to claim 1,
there is an inflection point on the long side of the crystal piece, parallel to the short side of the crystal piece, at which the length of the crystal piece changes;
A length between the inflection point and one short side of the crystal piece in a direction parallel to the long side of the crystal piece is 5% or more and 20% or less of the length of the crystal piece. A crystal element characterized by: The crystal element according to claim 1 or claim 2,
When the side surface including the other short side of the crystal piece is viewed from the side,
A crystal element, wherein a concave portion is formed in a side surface including the other short side of the crystal piece. A crystal element according to any one of claims 1 to 3;
a base mainly composed of a substrate portion provided with a mounting pad on an upper surface thereof, to which a part of the connection lead-out portion of the crystal element is electrically connected;
a lid that is joined to the base and hermetically seals the crystal element;
a conductive member electrically connecting a portion of the connection lead-out portion and the mounting pad;
A crystal device having a A crystal device according to claim 4,
there is an inflection point on the long side of the crystal piece, parallel to the short side of the crystal piece, at which the length of the crystal piece changes;
A crystal device, wherein the conductive member is in contact with the inflection point when the crystal element is mounted on the base.

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