JP2019145948A - Crystal element and crystal device - Google Patents

Abstract

To provide a crystal element and a crystal device that can improve electrical characteristics.SOLUTION: A crystal element 120 includes a crystal piece 121 having a plurality of notches 122 formed side by side along an edge part, and a metal pattern 123 provided on the crystal element 121. The notches 122 have an arc shape in plan view, and the radius of curvature Rb of notches 122b formed at both ends of short sides of the crystal piece 121 is made large compared with the radius of curvature Ra of the other predetermined notches 122a.SELECTED DRAWING: Figure 3

Description

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

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

JP 2017-85385 A

  As described above, such a crystal element has a substantially rectangular crystal piece in plan view. When an alternating voltage is applied to the metal pattern, a contour vibration that is a secondary vibration is generated simultaneously with a thickness shear vibration that is a main vibration. The contour vibration depends on the external dimensions of the crystal piece. When a substantially rectangular crystal piece is used in plan view, the contour vibration, which is a secondary vibration, is changed to the thickness shear vibration, which is the main vibration. There is a possibility that the influence will be increased and the electrical characteristics will be deteriorated.

  The present invention has been considered in order to solve the above problems, and an object thereof is to provide a crystal element and a crystal device capable of improving electrical characteristics.

  The quartz crystal device according to the present invention is a metal pattern comprising a quartz piece formed by arranging a plurality of cuts along an edge, a pair of excitation electrode portions provided on the quartz piece, and a pair of connection lead portions. And having.

  According to said structure, the crystal element and crystal device with which the electrical property was improved can be obtained.

1 is a perspective view of a crystal resonator that is an example of a crystal device according to an embodiment of the present invention. It is sectional drawing in the AA cross section of FIG. It is a top view of the upper surface of the crystal element which concerns on embodiment of this invention. It is the elements on larger scale of the B section of FIG. It is a top view of the upper surface of the crystal piece used with the crystal element which concerns on embodiment of this invention. It is the elements on larger scale of the C section of FIG.

  Embodiments of the present invention will be described below with reference to the drawings. Note that 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 of crystal device)
FIG. 1 is a perspective view of a crystal resonator which is an example of a crystal device according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along a line AA in FIG.

  The quartz resonator is, for example, an electronic component having a generally thin and rectangular parallelepiped shape as a whole, and the dimensions thereof may be set as appropriate. For example, the length of the long side or the short side is 0.6 mm to 7.5 mm, and the thickness is 0.2 mm to 1.2 mm. Is 0.6 m to 3.2 mm, and the thickness is 0.2 mm to 0.8 mm.

  The crystal resonator includes, for example, a base 110 on which a recess is formed, a crystal element 120 accommodated in the recess, and a lid 130 that closes the recess. The concave portion is sealed by the lid body 130, and the inside thereof is, for example, evacuated or filled with a suitable gas (for example, nitrogen).

  The base 110 has a substrate portion 110a that is the main body of the base 110, a mounting pad 111 for mounting the crystal element 120, and an external terminal 112 for mounting a crystal resonator on a circuit board (not shown). doing. The board part 110a is provided on the surface of the board part 110a and / or inside the board part 110a, and is a conductor (not shown) for electrically joining the mounting pad 111 and the two predetermined external terminals 112. )have. The base 110 has a frame-like frame portion 110b for forming a recess in the base 110, for example. The frame part 110b is provided along the edge part of the upper surface of the board | substrate part 110a. The substrate portion 110a and the frame portion 110b constituting the base 110 are made of an insulating material such as ceramic, and the mounting pad 111 and the external terminal 112 are made of a conductive layer made of, for example, metal.

  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 includes a crystal piece 121 and a pair of metal patterns 123 provided on the crystal piece 121. The metal pattern 123 includes a pair of excitation electrode portions 124 for applying a voltage to the crystal piece 121 and a pair of connection lead portions 125 for mounting the crystal element 120 on the mounting pad 111.

  The crystal piece 121 is a so-called AT-cut crystal piece. That is, in quartz, an orthogonal coordinate system XYZ composed of an X axis (electric axis), a Y axis (mechanical axis), and a Z axis (optical axis) is, for example, 30 ° to 45 ° around the X axis (for example, When the Cartesian coordinate system XY′Z ′ is defined by rotating by 35 ° 15 ′), it is a plate shape cut out parallel to the XZ ′ plane. Therefore, the crystal piece 121 has a pair of main surfaces parallel to the XZ ′ plane.

  The metal pattern 123 includes an excitation electrode part 124 and a connection lead part 125. The pair of excitation electrode portions 124 is provided, for example, on the center 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 portions 125 extends, for example, from the pair of excitation electrode portions 124 in the X-axis direction (which may be either positive or negative), and is a connection portion (widening) outside the pair of main surfaces in the X-axis direction. 125a). For example, the connecting portion 125 a of the drawer connecting portion 125 is widened until it reaches the edge in the Z′-axis direction of the main surface of the crystal piece 121.

The crystal element 120 is accommodated in, for example, a recess of the base 110 with the main surface of the crystal piece 121 opposed to the upper surface of the substrate portion 110a of the base 110. The connection part 125 a of the drawer connection part 125 is joined to the mounting pad 111 of the base body 110 by the bump 140. Thereby, the crystal element 120 is supported like a cantilever on the substrate portion 110a of the base 110. At this time, the connection part 125a of the drawer connection part 125 and the mounting pad 111 of the base 110 are electrically connected. Accordingly, the pair of excitation electrode portions 124 is electrically connected to the connection wiring portion 125, the bump 140, and the mounting pad 111, and thus is electrically connected to any two of the plurality of external terminals 112. The bump 140 is made of, for example, a conductive adhesive.

  For example, the crystal unit is mounted on the circuit board by disposing the lower surface of the base 110 so as to face the mounting surface of the circuit board (not shown) and bonding the external terminals 112 onto the pads of the circuit board with solder or the like. The For example, an oscillation circuit 23 is configured on the circuit board. The oscillation circuit applies an alternating voltage to the pair of excitation electrode portions 124 via the external terminal 112 and the mounting pad 111 to generate an oscillation signal. At this time, the oscillation circuit uses, for example, fundamental wave vibration among thickness shear vibrations of the crystal piece 121.

(Details of planar shape of crystal element)
FIG. 3 is a plan view of the upper surface of the crystal element 120 according to the present embodiment. The center C0 is the center (graphic gravity center) of the crystal piece 121. The center line Kx0 is a straight line passing through the center C0 and parallel to the X axis. The center line Kz0 is a straight line that passes through the center C0 and is parallel to the Z ′ axis.

(Planar shape of crystal piece)
FIG. 5 is a plan view of the top surface of the crystal piece 121 in plan view, and FIG. 6 is a partially enlarged view of a portion C in FIG.

  As shown in FIG. 5, the crystal piece 121 is generally rectangular with the longitudinal direction as the X-axis direction, and a plurality of cuts 122 (122 a, 122 b) are formed along the outer edge thereof.

  The main surface of the crystal piece 121 faces a pair of short sides facing each other in the X-axis direction and faces each other in the Z-axis direction, and connects both ends of the pair of short sides (extends between the pair of short sides). It has a pair of long sides. The term “side” is strictly a straight line, but in the present embodiment, it may be other than a straight line for convenience.

  The cuts 122 are formed side by side along the outer edge of the main surface of the crystal piece 121. At this time, the adjacent notch 122 does not need to be connected to the outer edge of the notch 122. For example, the length parallel to the side between the outer edges of the adjacent cuts 122 is shorter than the inner diameter (side length) of the cuts 122.

  Further, as shown in FIGS. 3 and 4, the notch 122 has an arc shape in plan view. At this time, the center (curvature center) of the arc-shaped circle is located on the edge of the main surface of the crystal piece 121 or on the outside.

In addition, the notch 122 is a notch 122a in which a curvature radius Rb of a notch 122b formed at a predetermined side, for example, both ends of one short side is formed near the midpoint of the long side and the short side. Is larger than the curvature radius Ra.
Various dimensions of the crystal piece 121 may be set as appropriate. For example, the length L (X-axis direction) is 0.4 mm to 7.2 mm, and the width W (Z′-axis direction) is 0.3 mm to 5.0 mm.

  The bending vibration that is easily combined with the thickness shear vibration is bending vibration (thickness bending vibration) when the XY ′ plane is viewed. In an AT-cut quartz piece having a relatively small thickness, the frequency of thickness bending vibration is approximately inversely proportional to the square of the length in the X-axis direction. When the length in the X-axis direction is less than 1 mm, the frequency of bending vibration becomes relatively high and approaches the frequency of the fundamental wave vibration among the thickness shear vibrations. As a result, the bending vibration is easily coupled to the thickness shear vibration.

  However, when the notches 122 are formed side by side along the edge of the main surface of the crystal piece 121, the portion where the notches 122 are formed in the vicinity of the side (long side) parallel to the X axis of the crystal piece 121. Is discontinuous in the X-axis direction. For this reason, the length in the X-axis direction partially changes in the vicinity of the long side, and the frequency of bending vibration is dispersed around the long side. As a result, the possibility that the bending vibration becomes large at a constant frequency and is strongly coupled to the thickness shear vibration is reduced. As a result, it is possible to reduce the risk of a decrease in electrical characteristics such as an increase in the equivalent series resistance value of the crystal element 120.

  Further, in the AT-cut crystal piece, contour vibration in a plan view of the main surface of the crystal piece 121 may also occur. This contour vibration is also easily coupled to the thickness shear vibration when the frequency approaches the frequency of the thickness shear vibration. The frequency of the contour vibration is defined by the dimension of the main surface of the crystal piece 121 in plan view, and the dimension in the Z′-axis direction is set so that the contour vibration is not coupled to the thickness shear vibration. However, due to manufacturing errors, the contour vibration frequency may deviate from the intended frequency and may be coupled to the thickness shear vibration.

  However, when the cuts 122 are formed side by side along the edge of the main surface of the crystal piece 121, the cuts 122 are formed in the vicinity of the side (short side) parallel to the Z ′ axis of the crystal piece 121. The portion is discontinuous in the Z′-axis direction. For this reason, the length in the Z′-axis direction partially changes in the vicinity of the short side, and the frequency of the contour vibration is dispersed around the short side. As a result, the risk that the contour vibration increases at a constant frequency and is strongly coupled to the thickness shear vibration is reduced. As a result, it is possible to reduce the risk of a decrease in electrical characteristics such as an increase in the equivalent series resistance value of the crystal element 120.

  Further, by forming the arc-shaped cut 122 in plan view of the crystal element 120, the length in the X-axis direction in the vicinity of the edge of the main surface of the crystal piece 121 depends on the position in the Z′-axis direction. Can be changed. As a result, the frequency of the bending vibration is dispersed around the long side. As a result, the possibility that the bending vibration becomes large at a constant frequency and is strongly coupled to the thickness shear vibration is reduced. As a result, it is possible to reduce the risk of a decrease in electrical characteristics such as an increase in the equivalent series resistance value of the crystal element 120.

  Moreover, by making it circular arc shape in this way, compared with the case where the notch 122 combines a straight line like a sawtooth, it can reduce that a notch | chip is missing. As a result, it is possible to reduce the risk of deterioration of electrical characteristics due to chipping of the crystal piece 121.

  Further, in plan view, the curvature radius Rb of the notches 122b formed at both ends of the short side is made larger than the curvature radius Ra of the other notches 122a, so that one of the crystal pieces 121 In the vicinity of the short side, the length in the X-axis direction can be changed according to the position of the Z′-axis while the length in the Z′-axis direction can be changed according to the position of the X-axis. As a result, the possibility that the bending vibration and the contour vibration increase at a constant frequency and are strongly coupled to the thickness shear vibration is reduced. As a result, it is possible to reduce the risk of a decrease in electrical characteristics such as an increase in the equivalent series resistance value of the crystal element 120.

(Details of excitation electrode)
FIG. 3 is a plan view when the upper surface of the crystal element 120 is viewed in plan.

  The excitation electrode portion 124 is generally formed in a rectangular shape whose longitudinal direction is the X-axis direction. That is, the excitation electrode portion 124 is opposed to each other in the X-axis direction and is opposed to each other in the Z′-axis direction, and connects both ends of the pair of short sides (extends between the pair of short sides). ) A pair of long sides.

  The planar shape of the excitation electrode 124 is, for example, a line-symmetric shape with respect to a center line Kx0 parallel to the X axis. The corners of the excitation electrode portion 124 may be chamfered.

  In the Z′-axis direction, the excitation electrode portion 124 is located at the center of the main surface of the crystal piece 121, for example, and the center of the excitation electrode portion 124 (the center of gravity of the excitation electrode portion 124) C1 is a center parallel to the X axis. While located on the line Kx0, it is shifted to the free end side from the center C0 of the main surface of the crystal piece 121.

(Details of connection drawer)
3 is a plan view of the crystal element 120 as viewed from above, and FIG. 4 is a partially enlarged view of a portion B in FIG.

  As described above, the connection lead part 125 is composed of the connection part 125a and the lead part 125b. A part of the connection part 125 a which is a part of the connection wiring part 125 is formed on the inner wall of the notch 122 b formed at both ends of one short side of the crystal piece 121.

  Thus, by forming a part of the connection lead part 125 on the inner wall of the notch 122b formed at both ends of one short side of the crystal piece 121, the connection lead part 125 serves as a weight, In the vicinity of one short side of the crystal piece 121, bending vibration and contour vibration can be made difficult to occur. As a result, the possibility that the bending vibration and the contour vibration are combined with the thickness shear vibration can be reduced, and the deterioration of the electrical characteristics can be reduced.

  As described above, the crystal element 120 according to the present embodiment includes the crystal piece 121 in which a plurality of cuts 122 are formed along the edge, and the metal pattern 123 provided in the crystal piece 121. .

  From another viewpoint, it can be said that such a crystal element 120 has a discontinuous portion at the edge of the crystal piece 121 when viewed in plan. Therefore, the bending vibration and the contour vibration can be dispersed at the edge of the crystal piece 121, and the possibility that the bending vibration and the contour vibration are combined with the thickness shear vibration can be reduced. As a result, it is possible to reduce the risk of a decrease in electrical characteristics such as an increase in the equivalent series resistance value of the crystal element 120.

  In addition, the crystal element 120 has a notch 122 having an arc shape in plan view.

  By doing so, the length in the X-axis direction can be changed in the vicinity of the long side according to the position in the Z′-axis direction. As a result, the frequency of the bending vibration is dispersed around the long side. As a result, the possibility that the bending vibration becomes large at a constant frequency and is strongly coupled to the thickness shear vibration is reduced. As a result, it is possible to reduce the risk of a decrease in electrical characteristics such as an increase in the equivalent series resistance value of the crystal element 120.

  Moreover, by making it circular arc shape in this way, compared with the case where the notch 122 combines a straight line like a sawtooth, it can reduce that a notch | chip is missing. As a result, it is possible to reduce the risk of deterioration of electrical characteristics due to chipping of the crystal piece 121.

  Further, the crystal element 120 has a substantially rectangular crystal piece 121 in plan view, and the curvature radius Rb of two predetermined notches 122b formed at both ends of a predetermined one side of the crystal piece 121 is: It is larger than the radius of curvature Ra of another predetermined notch 122a.

In this way, in the vicinity of one short side of the crystal piece 121, the length in the X-axis direction is changed according to the position of the Z′-axis while the length in the Z′-axis direction is changed to the position of the X-axis. It becomes possible to change according to. As a result, the possibility that the bending vibration and the contour vibration increase at a constant frequency and are strongly coupled to the thickness shear vibration is reduced. As a result, it is possible to reduce the risk of a decrease in electrical characteristics such as an increase in the equivalent series resistance value of the crystal element 120.

  Further, the crystal element 120 is formed so that the cutout portions 122 (122a, 122b) are line-symmetric with respect to the center Kx0 (a straight line passing through the center C0 and parallel to the X axis) in plan view. Yes. By doing in this way, the way of vibration in the Z′-axis direction can be made the same. As a result, the vibration balance changes due to the difference in the vibration method in the Z′-axis direction, and it is possible to reduce the deterioration of the electrical characteristics.

  In addition, the crystal element 120 has a radius of curvature Rb in plan view, the notches 122b are formed at the four corners of the crystal piece 121, and are symmetrical with respect to the center line Kz0. By doing in this way, the way of vibration in the Z′-axis direction can be made the same. As a result, the vibration balance changes due to the difference in the vibration method in the Z′-axis direction, and it is possible to reduce the deterioration of the electrical characteristics.

  Further, the crystal element 120 has a predetermined two cuts (formed at both ends of a predetermined side of the crystal piece 121), in which a part of the connection lead part 125, specifically, a part of the connection part 125a is formed. It is formed on the inner wall of 122b.

  By doing in this way, the connection drawer | drawing-out part 125 will play the role of a weight, and it can make it hard to produce bending vibration and outline vibration in the one short side vicinity of the crystal piece 121. FIG. As a result, the possibility that the bending vibration and the contour vibration are combined with the thickness shear vibration can be reduced, and the deterioration of the electrical characteristics can be reduced.

  Further, in this way, when the metal pattern 123 is formed on the crystal piece 121 by using a vapor deposition method or a sputtering method, a metal film can be provided on the inner wall portion of the notch 122b in the predetermined two notches 122b. Therefore, the upper surface of the crystal piece 121 and the lower surface of the crystal piece 121 can be reliably electrically connected. As a result, it is possible to reduce a decrease in electrical characteristics such that the metal pattern 123 is partially thinned at the inner wall portion of the cut 122 and the equivalent series resistance value is increased.

  The quartz crystal device according to the present embodiment has such a quartz crystal element 120, a base 110 mainly composed of a substrate portion 110a on which the quartz crystal element 120 is mounted, and the quartz crystal element 120 which is bonded to the base 110 and is hermetically sealed. And a lid 130.

  Since such a quartz crystal device includes a quartz crystal element that can reduce deterioration in electrical characteristics, it is possible to reduce deterioration in electrical characteristics.

  Further, in such a crystal device, a part of the connection part 125a of the connection wiring part 125 is provided on the inner wall part of the predetermined two cuts 122b formed at both ends of one short side of the crystal piece 121. A part of the connecting portion 125a is joined to the bump 140 (conductive adhesive in this embodiment). Therefore, the crystal device is held by one short side of the crystal element 120. For this reason, the influence on the thickness shear vibration by the bump 140 can be reduced, and the deterioration of the electrical characteristics can be reduced.

  The present invention is not limited to the above-described embodiments, and may be various aspects.

The crystal device is not limited to a crystal resonator. For example, the crystal device may be an oscillator including a portion that becomes a crystal resonator and a portion that becomes an oscillation circuit. Further, the crystal resonator may include other electronic components such as a thermistor, a diode, or a transistor in addition to the crystal element.

  The crystal element may not be a flat plate, but may be a mesa type having a thick central portion.

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

  The connection lead part extends from the excitation electrode part to one short side of the crystal piece. For example, one connection lead part extends to one short side of the crystal piece while the other connection The lead portion may extend to the other short side of the crystal piece.

  The connection lead portion does not have to be linearly extended along the X-axis direction, for example, it may extend along the short side of the crystal piece after extending to the long side of the crystal piece. Good.

  The case where the radius of curvature of the predetermined two cuts formed at both ends of one short side of the crystal piece is larger than the radius of curvature of the other predetermined cut is explained. The curvature radii of the cuts formed at both ends of the slab may be the same as or larger than the curvature radii of the two predetermined cuts.

Base body ... 110
Substrate part 110a
Frame part 110b
Mounting pad ... 111
External terminal ... 112
Quartz element ... 120
Crystal piece ... 121
Incision ... 122
Two predetermined cuts ... 122b
Other predetermined cuts 122a
Metal pattern ... 123
Excitation electrode part 124
Connection lead-out part ... 125
Connection part ... 125a
Pull-out part ... 125b
Lid ... 130
Bump ... 140

Claims (5)

A crystal piece in which a plurality of cuts are formed along the edge;
A metal pattern comprising a pair of excitation electrode portions provided on the crystal piece, and a pair of connection lead portions;
Crystal element having The crystal element according to claim 1,
A crystal element, wherein the cut has an arc shape in plan view. The crystal element according to claim 2,
In plan view
The crystal piece is substantially rectangular,
A crystal element, wherein a radius of curvature of two predetermined cuts formed at both ends of a predetermined side of the crystal piece is larger than a radius of curvature of a predetermined other cut. . The crystal element according to claim 3,
A part of the connection drawer is formed on an inner wall of the two predetermined cuts. The crystal element according to claim 1 to claim 4,
A substrate mainly composed of a substrate portion on which the crystal element is mounted;
A lid bonded to the base and hermetically sealing the crystal element;
A crystal device characterized by comprising: