WO2023112962A1

WO2023112962A1 - Crystal oscillator and crystal device

Info

Publication number: WO2023112962A1
Application number: PCT/JP2022/046045
Authority: WO
Inventors: 隼人田中; 斉師吉田
Original assignee: 京セラ株式会社
Priority date: 2021-12-15
Filing date: 2022-12-14
Publication date: 2023-06-22

Abstract

Provided are a crystal oscillator and a crystal device with which an electrical signal that is in accordance with vibration can be obtained at a more appropriate ESR. A crystal oscillator (12) comprises: a crystal piece (121) that has a resonant frequency of 100 MHz or higher; two excitation electrodes (122) to which a voltage relating to the resonance of the crystal piece (121) is applied; two mounting electrodes (124) that are located offset toward the side of one end of the crystal piece (121), and are connected to an external part; and two extraction electrodes (123) that connect the respective excitation electrodes (122) and mounting electrodes (124). The centers of the excitation electrodes (122) are located further to the side that is close to the mounting electrodes (124) than the location of the center of the crystal piece (121), and the two extraction electrodes (123) are connected between the excitation electrodes (122) and the mounting electrodes (124) in straight lines that are not parallel to one another.

Description

Crystal resonator element and crystal device

The present disclosure relates to crystal oscillators and crystal devices.

In a crystal resonator element that resonates a crystal blank to output a signal of a desired frequency, the quality of vibration deteriorates when the vibration reaches the edge of the crystal blank. An excitation electrode is located across which a voltage associated with resonance is applied. When the resonance frequency becomes high, the plane view size of the excitation electrode can be made smaller than that of the crystal piece. In this case, Japanese Patent Application Laid-Open No. 2017-050751 discloses that the extraction direction of extraction electrodes that connect the excitation electrodes and the mounting electrodes for external connection is set with respect to the X-axis (electrical axis) direction related to the vibration of the crystal piece. Equivalent Serial Resistance (ESR) or Crystal Impedance (CI) is suppressed from increasing by setting an appropriate angle.

One aspect of the present disclosure is
a crystal piece having a resonance frequency of 100 MHz or higher;
two excitation electrodes to which a voltage related to resonance of the crystal piece is applied;
two mounting electrodes located close to one end of the crystal piece and connected to the outside;
two extraction electrodes respectively connecting the excitation electrodes and the mounting electrodes;
with
the center of the excitation electrode is positioned closer to the mounting electrode than the center position of the crystal blank,
The two extraction electrodes are crystal vibrating elements that connect the excitation electrodes and the mounting electrodes in non-parallel and straight lines.

FIG. 2 is a perspective view showing the configuration of the crystal device of the present embodiment with the lid removed. 1 is a cross-sectional view of a quartz device; FIG. It is a top view in the state which removed the lid|cover of the crystal device. It is an experiment result which shows the temperature characteristic of ESR when an extraction electrode has a bend. It is an experiment result which shows the temperature characteristic of ESR when an extraction electrode does not bend. 5 is a graph showing experimental results of ESR depending on the width of the extraction electrode; 5 is a graph showing experimental results of ESR depending on the width of the extraction electrode; 5 is a graph showing experimental results of ESR depending on the width of the extraction electrode;

Embodiments will be described below with reference to the drawings.
1A and 1B are diagrams showing the configuration of a crystal device 1 of this embodiment. 1A is a perspective view showing a state in which the lid body 14 is removed, and FIG. 1B is a cross-sectional view taken along the cross-sectional line AA in FIG. 1A.
The crystal device 1 includes a base 11, a crystal vibrating element 12, a conductive adhesive 13, a lid 14, parts 15, and the like.

The base 11 has a bottom plate 111 and side walls 112 positioned on the periphery of the upper surface of the bottom plate 111, and has a box-like shape with a recess 11a surrounded by the bottom plate 111 and the side walls 112. An electrode pad 113 is positioned on the bottom surface of the recess 11a. In addition, external connection pads 114 are located on the back surface (surface on the −z side) of the bottom plate 111 . In the drawing, a dotted line is shown between the bottom plate 111 and the side wall portion 112 for the sake of explanation, but they are actually integrated.

The crystal vibrating element 12 is connected to the electrode pad 113 via the conductive adhesive 13 . The electrode pads 113 are electrically connected to external connection pads 114 via electrical wiring (not shown) located inside the base 11 . Note that the electrode pads 113 may be positioned on the projecting portion positioned on the upper surface of the bottom plate 111 .

The external connection pads 114 are connected to the module board or the like using, for example, solder, so that the crystal device 1 can transmit and receive signals to and from the external module board and the like.

The crystal vibrating element 12 has a crystal piece 121, an excitation electrode 122, an extraction electrode 123, a mounting electrode 124, and the like. The mounting electrode 124 is an electrode for mounting the crystal vibrating element 12 on the base 11, and near the end of the crystal piece 121 on the +x side, here, two (a pair of)

mounting electrodes

1241 and 1242 are respectively mounted. They are positioned in contact with the ends on the +x side and are connected and fixed to the electrode pads 113 via the conductive adhesive 13 . Thereby, the excitation electrode 122 is connected to the outside through the electrode pad 113 and the external connection pad 114 . Thus, the crystal vibrating element 12 is in a cantilevered state.

The excitation electrode 122 has two excitation electrodes 1221 on the lower surface side of the crystal piece 121 (the side facing the bottom plate 111, -z side) and an excitation electrode 1222 on the upper surface side (+z side). These two excitation electrodes 122 are located at the same position in plan view from the upper surface side. The excitation electrode 1221 is electrically connected to the mounting electrode 1241 via the extraction electrode 1231 . The excitation electrode 1222 is electrically connected to the mounting electrode 1242 via the extraction electrode 1232 . A mounting electrode 1242 connected to the extraction electrode 1232 located on the upper surface side spreads over both upper and lower surfaces. As a result, the external connection pad 114 and the excitation electrode 122 are connected to each other via the conductive adhesive 13 on the lower surface side of the crystal vibrating element 12, and a voltage for resonance is applied. That is, a voltage signal is applied to the excitation electrodes 122 to vibrate (excite) the crystal blank 121 , or a voltage generated between the excitation electrodes 122 is output to the external connection pads 114 .

The crystal piece 121 is, for example, an AT-cut rectangular piece, and has a thickness corresponding to the resonance frequency to be output. Normally, the higher the resonance frequency, the thinner the crystal piece 121 becomes. Although not particularly limited, here, the crystal piece 121 has a resonance frequency of 100 MHz or higher. Note that the crystal piece 121 is not limited to having a uniform thickness as a whole. The portion of the mounting electrode 124 may be thicker than the thickness of the contact area with the excitation electrode 122 that causes vibration and the thickness of the surrounding area (these are referred to as a vibrating portion). It may have a relatively thick portion surrounding the vibrating portion. Alternatively, conversely, crystal piece 121 may have a shape in which the periphery is relatively thin compared to the vibrating portion. The direction (X-axis direction) along the crystal axis (electrical axis) of the crystal blank 121 coincides with the x-axis direction in the drawing, and the sides extending in the X-axis direction are the long sides of the rectangular shape (rectangle). there is

A lid 14 is joined to the upper end surface of the side wall portion 112 surrounding the concave portion 11a of the base 11 with a brazing material or the like. Between the side wall portion 112 and the lid 14, a metallized layer (not shown), which is a frame-shaped conductor and has substantially the same shape as the side wall portion 112 in plan view, may be positioned. The metallized layer may be a conductive layer obtained by coating and firing, or may be a plated layer. The recessed portion 11a is sealed by the lid 14 to block entry and exit of air, dust, and the like with the outside. The base 11 and the lid 14 are a housing that accommodates the crystal vibrating element 12 in the crystal device 1 of this embodiment.

The part 15 is positioned on the bottom side of the base 11 . The component 15 may be an electronic component such as an IC chip, or may be a sensor such as a temperature detecting element (thermistor, etc.). Also, the parts 15 may be of the same type or a combination of multiple types. These are for outputting supplementary information relating to adjustment of the resonance frequency of the crystal oscillator 12, or performing adjustment according to the supplementary information. That is, the crystal device 1 may be a crystal oscillator. . Note that the position of the component 15 may not be near the center of the bottom surface in plan view, but may be at a deviated position.

Here, the substrate 11 is not particularly limited, but may be, for example, a ceramic material, a semiconductor material, a glass material, or a crystal, or a combination thereof. (including things). The conductive electrode pads 113 may be printed on the substrate 11, for example, and the uppermost surface thereof may be plated with gold, for example.
Also, the conductive adhesive 13 may be, for example, a resin-based (silicone-based resin, epoxy resin, or the like) adhesive containing a silver filler. In particular, the conductive adhesive 13 made of silicone resin is soft even after being adhered, so it is less likely to adversely affect vibrations.
Also, the lid 14 is a metal conductor flat plate, for example, a metal containing iron, copper, nickel, chromium, cobalt, molybdenum or tungsten, or an alloy thereof.

Next, the crystal resonator element 12 of this embodiment will be described in more detail.
FIG. 2 is a plan view of the crystal device 1 of this embodiment with the cover 14 removed. A portion of the configuration that cannot be seen from the top side is indicated by a dashed line. A dotted line indicates the center of the crystal vibrating element 12 in the x-axis direction (direction along the long side).

The excitation electrode 122 of the crystal vibrating element 12 is here circular. Further, the center position of the excitation electrode 122 is closer to the mounting electrode 124 side than the center position of the crystal vibrating element 12 . The excitation electrode 122 has an area approximately equal to or slightly smaller than that of the vibrating portion of the crystal piece 121 at a resonance frequency of 100 MHz or more. If this area is close to the area of the crystal piece 121, the vibration characteristics are degraded due to the influence of the edge of the crystal piece 121. FIG. The vibration characteristics are also affected by the angle of the excitation electrode 122 . Here, by rounding the corners of the excitation electrode 122 to make it particularly circular in plan view, the adverse effect on the vibration characteristics is reduced.

When the resonance frequency is as high as 100 MHz or higher, the length of the crystal blank 121 in the x-axis direction (that is, the X-axis direction) can be shortened accordingly, but it does not necessarily have to be shortened. Here, the length of the side (long side) of the crystal piece 121 in the x-axis direction can be in the range of 0.8 to 1.4 mm, for example. Also, the length of the side (short side) of the crystal blank 121 in the y-axis direction can be in the range of 0.4 to 1.0 mm, for example.

If the center of the excitation electrode 122 having such a size is positioned away from the mounting electrode 124 in order to suppress the influence on the vibration of the mounting electrode 124 and the like as in the conventional art, the extraction electrodes 1231 and 1232 (summarization) , the two lead-out electrodes 123) become longer. Since the lead-out electrode 123 is thinner than the excitation electrode 122, the mounting electrode 124, etc., if it becomes longer, it leads to an increase in ESR (CI). As described above, in the crystal vibrating element 12 having a resonance frequency of 100 MHz or more, the vibration does not spread outside the range of the excitation electrodes 122. Therefore, the extraction electrodes 123 are not advantageous in separating the excitation electrodes 122 from the mounting electrodes 124 and the like. The disadvantage of being longer is greater. Therefore, in this crystal vibrating element 12 , the center position of the excitation electrode 122 in plan view is closer to the mounting electrode 124 than the center position of the crystal piece 121 in plan view. The length M1 (distance) between the center position of the excitation electrode 122 and the center position of the crystal piece 121 in plan view is usually greater than 0 μm and less than 550 μm, preferably greater than 0 μm and less than or equal to 540 μm. , particularly preferably larger than 0 μm and 440 μm or less. The ratio of the length M1 to the length of the side (long side) of the crystal piece 121 in the x-axis direction is usually 0.393 or less, preferably 0.386 or less, and particularly preferably 0.315 or less. be. If the excitation electrode 122 is too small, the voltage amplitude required to obtain the necessary vibration will be large, resulting in poor efficiency. When the excitation electrode 122 is circular, the inner diameter (diameter) of the excitation electrode 122 is usually 150 μm or more and 900 μm or less, preferably 160 μm or more and 600 μm or less, and particularly preferably 170 μm or more and 400 μm or less. The area ratio of the excitation electrode 122 to the vibrating portion of the crystal element 121 in plan view is usually 0.005 or more and 0.785 or less, preferably 0.060 or more and 0.500 or less, and particularly preferably 0.060 or more and 0.500 or less. 070 or more and 0.130 or less.

Further, in the crystal vibrating element 12, the two lead-out electrodes 123 are non-parallel to each other, and are straight lines extending in a direction inclined with respect to the side E1 of the rectangular mounting electrode 124 on the excitation electrode 122 side. . Since the lead-out electrode 123 does not have a bent portion, it is possible to shorten the connection points between the mounting electrodes 124 and the excitation electrodes 122 . When the mounting electrode 124 is located close to the short side of the crystal piece 121, the ratio of the side E1 to the short side of the crystal piece 121 is usually 0.10 or more and less than 0.50, preferably 0.18 or more and 0.50. 0.45 or less, and particularly preferably 0.20 or more and 0.40 or less. In addition, when the frequency is high, the reflection of the signal due to the bending of the extraction electrode 123 cannot be ignored. In particular, when the excitation electrode 122 is circular and has a curved edge, the length of the lead-out electrode 123 is appropriately adjusted when the direction radially extending from the center of curvature is closer to the direction perpendicular to the side E1 than the direction perpendicular to the side E1. easy to be In addition, since the lead-out electrode 123 does not extend in the direction perpendicular to the side E1, ie, in the x-direction, the influence on the vibration of the crystal piece 121 can be reduced. If the lead-out electrode 123 is not parallel to the x-direction, the magnitude of the inclination angle φ has little effect on the improvement of the ESR. Although not particularly limited, the angle φ is, for example, about 115 to 130 degrees.

In addition, the width W of the lead-out electrode 123 perpendicular to the extending direction varies from the width L1 at the connection position from the connection position with the excitation electrode 122 to the width L2 toward the connection position with the mounting electrode 124. and may be gradually increased. Simply put, the thicker the lead-out electrode 123 is, the more the increase in ESR (CI) can be suppressed. Therefore, ideally, the ESR does not decrease. Further, in high-frequency band signal transmission, if there is a sudden (discontinuous) width change in the middle of the wiring, a characteristic impedance mismatch will occur, and the wiring resistance will tend to increase. It can also lead to spurious emissions and deterioration of fitting. Also, it is necessary to match the impedance between the mounting electrode 124 and the excitation electrode 122 . Therefore, by gradually increasing the width of the extraction electrode 123 from the connection position with the excitation electrode 122 toward the connection position with the mounting electrode 124, it is possible to appropriately match the impedance while suppressing an increase in ESR.

When the width W gradually increases from the width L1 at the connection position with the excitation electrode 122 to the width L2 at the connection position with the mounting electrode 124, the width L1 at the connection position with the excitation electrode 122 is shorter than the side E1. Although there is no particular limitation, it is usually 30 μm or more and 180 μm or less, preferably 35 μm or more and 150 μm or less, and particularly preferably 40 μm or more and 120 μm or less. The ratio of the width L1 to the side E1 is usually 0.15 or more and less than 1, preferably 0.2 or more and 0.9 or less, and particularly preferably 0.3 or more and 0.8 or less.

Width L2 at the connection position with mounting electrode 124 is not particularly limited as long as it is longer than width L1 and equal to or less than side E1. It is preferably 40 μm or more and 120 μm or less. The ratio of the width of the excitation electrode 122 to the side E1 (the side parallel to the short side of the crystal piece 121 in the case of a square, the diameter in the case of a circle) is usually 0.03 or more and 0.50 or less, preferably , 0.10 or more and 0.45 or less, particularly preferably 0.20 or more and 0.40 or less.

The ratio of width L1 to width L2 is usually 0.15 or more and less than 1, preferably 0.2 or more and 0.9 or less, and particularly preferably 0.3 or more and 0.8 or less. It is preferable that the ratio of the width L2 to the width L1 is within the above range, since spurious vibration is less likely to occur and wiring resistance is less likely to increase.

3A and 3B are experimental results showing temperature characteristics of ESR depending on whether or not the extraction electrode 123 is bent.
In this experiment, the crystal piece 121 (long side 1166 μm, short side 787 μm) has a vibrating portion (long side 350 μm, short side 350 μm) corresponding to the circular excitation electrode 122 having a diameter of 330 μm. A length M1 between the center position and the center position of the crystal piece 121 in plan view is 170 μm. The distance from the mounting electrode 124 of the vibration electrode 122 is different, and the extraction electrode 123 with a width of 75 μm is connected to the same position of the excitation electrode 122 and the mounting electrode 124 (side E1: 180 μm). The angle between the direction of the extraction electrode 123 extending from the connection position with the excitation electrode 122 and the tangential line at the connection position with the mounting electrode 124 is 125 degrees. In FIG. 3A, the distance is long, and the extraction electrode 123 is bent and connected perpendicularly to the side E1. In FIG. 3B, the distance is short, and the extraction electrode 123 is connected directly obliquely to the side E1 without bending. Between FIG. 3A and FIG. 3B, there is a length difference of about 190 μm per lead electrode. The thickness of the electrode and extraction electrode is 210 nm each.

The unbent lead-out electrode 123 directly and obliquely connects the side E1 of the mounting electrode 124 and the excitation electrode 122, thereby lowering the ESR, which is sufficiently below 20Ω which is acceptable for product quality. I understand.

4A to 4C are graphs showing experimental results of ESR in which the width W of the extraction electrode 123 was set as shown below in the crystal resonator element 12 used in FIG. 3B. 4A shows a shape in which the width W is 75 μm, FIG. 4B shows a shape in which the width W gradually increases from 75 μm (L1) to 105 μm (L2), and FIG. 4C shows a case in which the width W is 105 μm. The angle formed by the extraction electrode 123 with respect to the tangent to the connection position between the extraction electrode 123 and the mounting electrode 124 in FIG. 4B is in the range of 116 to 131 degrees.

It can be seen that when the width W is varied from 75 to 105 μm, the ESR is significantly reduced compared to when the width W is constant at 75 μm. Also, compared with the case where the width W is constant at 105 μm, the ESR is lowered in the temperature range of about 0 to 100°C. As described above, it can be seen that the deterioration of the ESR of the crystal vibrating element 12 is effectively suppressed by widening the width W of the extraction electrode 123 while properly matching.

As described above, the crystal vibrating element 12 of this embodiment includes a crystal blank 121 having a resonance frequency of 100 MHz or higher, two excitation electrodes 122 to which a voltage related to resonance of the crystal blank 121 is applied, and one end of the crystal blank 121. , two mounting electrodes 124 connected to the outside, and two extraction electrodes 123 connecting the excitation electrode 122 and the mounting electrode 124, respectively. The center of the excitation electrode 122 is positioned closer to the mounting electrode 124 than the center position of the crystal piece 121, and the two lead-out electrodes 123 are non-parallel and linear to each other between the excitation electrode 122 and the mounting electrode 124. connected.
By positioning the excitation electrodes 122 in this manner, the extraction electrodes 123 can be efficiently shortened. In the crystal vibrating element 12 having a high resonance frequency, the vibration does not largely protrude from the range of the excitation electrode 122. Therefore, even if the excitation electrode 122 and the mounting electrode 124 are brought close to each other with such a positional relationship, the mounting electrode does not respond to the vibration. Since the influence of 124 is suppressed to be small, it is possible to suppress the increase in ESR (CI) and to vibrate appropriately. At this time, by setting the lead-out electrodes 123 in a non-parallel positional relationship, at least one of them (usually having the same shape and length) is tilted with respect to the vibration direction of the AT-cut crystal piece 121, so that the lead-out electrodes 123 can also reduce the influence on the vibration of In addition, since the extraction electrode 123 does not have a bent portion, it is possible to suppress signal reflection loss due to bending.

In addition, the width of the extraction electrode 123 perpendicular to the extending direction from the excitation electrode 122 gradually increases from the connection position with the excitation electrode 122 toward the connection position with the mounting electrode 124 . Thereby, an increase in ESR (CI) can be suppressed while matching impedance. In particular, by gradually increasing the width within a range of about 6 to 7 times depending on the impedance or the like, the crystal resonator element 12 can appropriately suppress an increase in ESR (CI).

Also, the length of the long side (along the X-axis direction) of the crystal piece 121 is 1.4 mm or less. The above effect can be obtained remarkably when the size is appropriate for the crystal piece 121 of the crystal vibrating element 12 having a high resonance frequency of 100 MHz or more.

Also, the ratio of the length M1 between the center position of the excitation electrode 122 and the center position of the crystal blank 121 to the length of the long side of the crystal blank 121 is set to 0.393 or less. Such positioning effectively shortens the distance between the excitation electrode 122 and the mounting electrode 124 to shorten the length of the extraction electrode 123, thereby reducing the equivalent series resistance. Along with this, an increase in ESR (CI) can be suppressed, and the oscillation of the crystal blank 121 can be properly maintained.

Further, the crystal device 1 of the present embodiment includes the crystal oscillator 12 described above. In this crystal device 1, accurate processing can be performed using a crystal oscillator 12 that operates more stably at an appropriate resonance frequency than before.

Note that the above-described embodiment is an example, and various modifications are possible.
For example, excitation electrode 122 may not be perfectly circular. The excitation electrode 122 may be elliptical or square with rounded corners (rectangular, diamond-shaped, etc.) as desired. If the excitation electrode 122 is too small, the voltage amplitude required to obtain the necessary vibration will be large, which is inefficient.

In addition, the size and shape of the crystal piece 121 may be appropriately adjusted according to the above conditions regarding the resonance frequency, the excitation electrode 122, and the like.

Also, the width of the lead-out electrode 123 need not be limited to that which simply gradually increases from the excitation electrode 122 toward the mounting electrode 124 . In addition to the ESR, it may be adjusted as appropriate according to conditions such as spurious and fitting, and contents that are preferentially required for the crystal device 1 .

Further, the crystal oscillator 12 may be sold or otherwise distributed separately from the substrate 11 or the like.
In addition, the specific configurations, structures, materials, and the like shown in the above embodiments can be changed as appropriate without departing from the gist of the present invention. The scope of the present invention includes the scope of the invention described in the claims and the scope of equivalents thereof.

The following concepts can be extracted from this disclosure.
(1)
a crystal piece having a resonance frequency of 100 MHz or higher;
two excitation electrodes to which a voltage related to resonance of the crystal piece is applied;
two mounting electrodes positioned close to one end of the crystal piece and connected to the outside;
two extraction electrodes respectively connecting the excitation electrodes and the mounting electrodes;
with
the center of the excitation electrode is positioned closer to the mounting electrode than the center position of the crystal blank,
The two extraction electrodes connect the excitation electrodes and the mounting electrodes in non-parallel and straight lines.
(2) The crystal oscillator according to (1), wherein the width of the extraction electrode perpendicular to the extending direction from the excitation electrode gradually increases from the connection position with the excitation electrode toward the connection position with the mounting electrode. element.
(3)
(2) The crystal oscillator according to (2), wherein a ratio of the width at the connection position with the mounting electrode to the width at the connection position with the excitation electrode is 0.15 or more and less than 1.0.
(4) The crystal resonator element according to any one of (1) to (3), wherein the length of the long side of the crystal piece is 1.4 mm or less.
(5) Any one of (1) to (4), wherein the ratio of the distance between the center position of the excitation electrode and the center position of the crystal blank to the length of the long side of the crystal blank is 0.393 or less. 1. A crystal oscillator according to claim 1.
(6) A crystal device comprising the crystal resonator element according to any one of (1) to (5).

This invention can be used for crystal oscillators and crystal devices.

Claims

a crystal piece having a resonance frequency of 100 MHz or higher;
two excitation electrodes to which a voltage related to resonance of the crystal piece is applied;
two mounting electrodes located close to one end of the crystal piece and connected to the outside;
two extraction electrodes respectively connecting the excitation electrodes and the mounting electrodes;
with
the center of the excitation electrode is positioned closer to the mounting electrode than the center position of the crystal blank,
The two extraction electrodes connect the excitation electrodes and the mounting electrodes in non-parallel and straight lines.
2. The crystal vibrating element according to claim 1, wherein the width of said lead-out electrode perpendicular to the extending direction from said excitation electrode gradually increases from the connection position with said excitation electrode toward the connection position with said mounting electrode.
3. The crystal oscillator according to claim 2, wherein a ratio of the width at the connection position with the mounting electrode to the width at the connection position with the excitation electrode is 0.15 or more and less than 1.0.
The crystal resonator element according to any one of claims 1 to 3, wherein the long side of the crystal piece has a length of 1.4 mm or less.
5. The ratio of the distance between the center position of the excitation electrode and the center position of the crystal blank to the length of the long side of the crystal blank is 0.393 or less. crystal oscillator.
A crystal device comprising the crystal resonator element according to any one of claims 1 to 5.