Base and crystal unit

Abstract

To provide a base for crystal vibrator having a novel structure utilizing inter-metal coupling and capable of reducing a mounting area by incorporating an input-side capacitor and an output-side capacitor.SOLUTION: A base 10 for crystal vibrator comprises a first substrate 20 and a second substrate 30 which are composed of glass or crystal. A second face 50 of the first substrate 20 and a first face 160 of the second substrate 30 are joined by inter-metal bonding, and at least one recess 100, which is recessed closer to both or one of the first substrate and the second substrate, is formed on a bonding interface. Two capacitors 110, which are used as an input or output-side capacitor of a crystal oscillator, are incorporated inside of the recess.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a base for a quartz crystal unit having a novel structure, and to a quartz crystal unit using this base. [Background technology]

[0002] A quartz crystal unit requires a container to house the quartz crystal blank. Therefore, various containers are being used or researched for quartz crystal units, including metal containers, ceramic containers, and containers made of glass or quartz crystal (see, for example, paragraph 0006 and Figure 1 of Patent Document 1). These containers consist of a base for mounting the quartz crystal blank and a lid member for sealing the quartz crystal blank.

[0003] Furthermore, a crystal unit is used as a crystal oscillator by being mounted on a substrate together with, for example, an integrated circuit including an oscillation circuit, an input capacitor, and an output capacitor (so-called load capacitance). The crystal unit, integrated circuit, input capacitor, and output capacitor are electrically connected to each other by, for example, a wiring pattern printed on the substrate (see, for example, paragraph 0012, Figure 5, etc. of Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2000-068780 [Patent Document 2] Patent Publication No. 2020-028095 Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, as electronic devices have become smaller, the mounting area of ​​electronic components has become smaller. However, in the case of the above-mentioned crystal oscillator, the crystal unit, integrated circuit, input capacitor, and output capacitor are each individually mounted on a substrate, which results in a problem of a large mounting area. Furthermore, among the various conventional containers described above, the most excellent ones at present are those using ceramic bases. However, as piezoelectric devices become thinner and smaller, ceramic bases are facing limitations in terms of structure, precision, and cost. Therefore, there is a need for a base with a novel structure that can replace ceramic bases, surpass the conventional containers using glass and / or quartz crystal, and also contribute to reducing the mounting area of ​​other electronic components such as capacitors.

[0006] The present invention has been made in consideration of the above points, and therefore, an object of the present application is to provide a base for a crystal resonator, which has a structure different from conventional structures, and which has a novel structure that can reduce the mounting area by incorporating an input-side capacitor and an output-side capacitor, and a crystal resonator using the base. [Means for solving the problem]

[0007] In order to achieve this object, the base for a quartz crystal resonator of the present invention comprises: a first substrate made of glass or quartz crystal; a pad provided on a first surface of the first substrate for mounting a quartz crystal blank; a second substrate made of the same material as the first substrate and bonded to the first substrate on a second surface opposite the first surface; at least one recess provided in the first substrate and the second substrate, recessed from the bonding interface toward both or one of the first and second substrates; two capacitors provided in the recess and used as an input capacitor and an output capacitor of the quartz crystal oscillator; an external connection terminal provided on the second surface of the second substrate opposite the first substrate for connecting the base to an external device; and wiring connecting the pad, the external connection terminal, and the two capacitors.

[0008] Furthermore, a quartz crystal unit according to the present invention is characterized in that it comprises a first substrate made of glass or quartz crystal; a pad provided on a first surface of the first substrate for mounting a quartz crystal blank; a second substrate made of the same material as the first substrate and bonded to the first substrate on a second surface opposite the first surface; at least one recess provided in the first substrate and the second substrate, recessed from the bonding interface toward both or one of the first and second substrates; two capacitors provided in the recess and used as an input capacitor and an output capacitor of the quartz crystal oscillator; an external connection terminal provided on the second surface of the second substrate opposite the first substrate for connecting the base to an external device; and wiring connecting the pad, the external connection terminal, and the two capacitors; a quartz crystal blank fixed to the mounting pad; and a lid member bonded to the base and sealing the quartz crystal blank. [Effects of the Invention]

[0009] According to the base of this invention, two capacitors used as input and output capacitors of a crystal oscillator are embedded in at least one recess provided in the first and second substrates and recessed from the bonding interface to both or either of the first and second substrates. This reduces the mounting area required for capacitor mounting, thereby promoting the miniaturization of electronic devices. Some crystal oscillators do not require high frequency accuracy. In such cases, the input and output capacitors may be slightly different from the capacitance that determines the target frequency, i.e., the specified load capacitance. The base of this invention is particularly useful as a base for constructing such rough crystal oscillators. Furthermore, the glass and quartz crystal components of the first and second substrates can be processed using photolithography, allowing for relatively high precision and relatively low material costs, resulting in a highly accurate and inexpensive base. Furthermore, according to the quartz crystal resonator of the present invention, a novel quartz crystal resonator can be realized using a base having the above-described novel structure. [Brief explanation of the drawings]

[0010] [Figure 1] Fig. 1A is a perspective view showing an outline of a base according to an embodiment of the present invention, and Fig. 1B is a cross-sectional view taken along line AA in Fig. 1A. [Figure 2] Fig. 1A is a plan view showing an outline of a first surface of a first substrate constituting the base of the present invention, and Fig. 1B is a plan perspective view showing an outline of a second surface of the first substrate. [Figure 3] Fig. 1A is a plan view showing an outline of a first surface of a second substrate constituting the base of the present invention, and Fig. 1B is a plan perspective view showing an outline of a second surface of the second substrate. [Figure 4] 1A is a perspective view showing an outline of a quartz crystal resonator according to a first embodiment of the present invention, and FIG. 1B is a cross-sectional view taken along line BB in FIG. [Figure 5] 1A is a perspective view showing an outline of a quartz crystal resonator according to a second embodiment of the present invention, and FIG. 1B is a cross-sectional view taken along line CC in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present invention will now be described with reference to the drawings. Base and crystal unit The following describes each of the embodiments. Note that the drawings used for the description are merely schematic illustrations to the extent that these inventions can be understood. In addition, in each drawing used for the description, similar components are designated by the same numbers, and their description may be omitted. Furthermore, the shapes, materials, etc. described in the following description are merely preferred examples within the scope of this invention. Therefore, the present invention is not limited to the following embodiments.

[0012] 1. Bass Fig. 1(A) is a perspective view showing an outline of a base 10 according to an embodiment of the present invention, and Fig. 1(B) is a cross-sectional view taken along line AA in Fig. 1(A). The base 10 of the present embodiment includes a first substrate 20 made of glass or quartz and having a rectangular or square shape in plan view, and a second substrate 30 made of the same material as the first substrate and also having a rectangular or square shape in plan view. The first substrate 20 and the second substrate 30 have substantially the same planar shapes, except for castellations (described later). The first substrate 20 and the second substrate 30 are bonded together by bonding a second surface 50 (see FIG. 2(B)) of the first substrate 20 to a first surface 160 (see FIG. 3(A)) of the second substrate 30. The bonding interface includes at least one rectangular recess 100, typically having a square shape in plan view and a predetermined depth, recessed into both or one of the first and second substrates 20 and 30. Two capacitors, for example, chip capacitors 110, are built into the recess 100 and used as input and output capacitors of the crystal oscillator. 1(B) shows, as an example, two recesses 100 recessed only on the first substrate 20 side. However, the recess 100 may be recessed on the second substrate 30 side, or a recess may be provided separately on each of the first substrate 20 and the second substrate 30. Also, there may be one recess, and two capacitors may be provided in it.

[0013] Mounting pads 140 (see FIG. 3A) for mounting capacitors are provided on the first surface 160 of the second substrate 30 at locations corresponding to the recesses 100. Providing the mounting pads 140 on the first surface 160 of the second substrate 30 in this way makes wiring easier and also makes it easier to mount the capacitors. However, the mounting pads 140 for mounting capacitors may also be provided inside the recesses 100. The capacitor mounting pads may utilize part of the metal film of the metal-to-metal bond.

[0014] In this way, since the capacitor is built in, the mounting area for mounting the capacitor can be reduced, which contributes to the promotion of miniaturization of electronic devices. Furthermore, since the first substrate 20 and the second substrate 30 are made of glass and quartz materials, they can be processed using photolithography technology, can be processed with relatively high precision, and since the material costs for both are relatively low, cost reductions can be achieved.

[0015] Next, the detailed configuration of each component of the first substrate 20, second substrate 30, etc. will be described. First, Fig. 2(A) is a plan view showing an outline of the first surface of the first substrate, and Fig. 2(B) is a plan perspective view showing an outline of the second surface of the first substrate. The first surface 40 of the first substrate 20 has a pad 60 for mounting a crystal blank, which is made of any suitable metal film, such as a laminated film of chromium and gold. The second surface 50, which is the opposite surface to the first surface 40, has two recesses 100 for respectively accommodating the two capacitors, a grounding metal film portion 120a that is wired to the ground terminal, an oscillation metal film portion 120b that is wired to the oscillation terminal, and an insulating portion 130 that electrically insulates the grounding metal film portion 120a and the oscillation metal film portion 120b. The insulating portion 130 is actually realized by removing the metal film from the second surface 50 of the first substrate 20 that constitutes the insulating portion 130. The crystal blank mounting pad 60 is connected to the oscillation metal film portion 120b by a via hole 70a and via hole wiring 70b provided on the first substrate 20. The via hole 70a and via hole wiring 70b can be formed using, for example, photolithography, etching, and film formation techniques. The via hole wiring 70b can be made of, for example, the same material as the crystal blank mounting pad 60.

[0016] Next, Fig. 3(A) is a plan view showing an outline of the first surface of the second substrate, and Fig. 3(B) is a plan perspective view showing an outline of the second surface of the second substrate. The first surface 160 of the second substrate 30 includes a grounding metal film portion 180a, an oscillation metal film portion 180b, and an insulating portion 190 that electrically insulates the grounding metal film portion 180a and the oscillation metal film portion 180b. The grounding metal film portion 180a, the oscillation metal film portion 180b, and the insulating portion 190 are arranged corresponding to the grounding metal film portion 120a, the oscillation metal film portion 120b, and the insulating portion 130, respectively, provided on the second surface 50 of the first substrate 20. The grounding metal film portion 180a and the oscillation metal film portion 180b are formed of a laminated film of any suitable metal film, such as a chromium film with a gold film laminated thereon. Therefore, these metal films can be used to realize metal-to-metal bonding between the first substrate 20 and the second substrate 30. A second surface 170 of the second substrate, which is the surface opposite to the first surface 160, is provided with external connection terminals 90a and 90b for earthing or oscillation.

[0017] Mounting pads 140 for mounting two capacitors 110 are provided on the first surface 160 of the second substrate 30 at locations corresponding to the two recesses 100 provided on the second surface 50 of the first substrate and corresponding to the terminals of the capacitors. These mounting pads 140 connect one end of each capacitor 110 to the earth metal film portion 180a and the other end to the oscillation metal film portion 180b.

[0018] Furthermore, the earth metal film portion 180a provided on the first surface 160 of the second substrate 30 is connected to the external connection terminal 90a provided on the second surface 170 of the second substrate by castellation wiring 150, and the oscillation metal film portion 180b provided on the first surface 160 of the second substrate 30 is connected to the external connection terminal 90b provided on the second surface 170 of the second substrate 30 by castellation wiring 150. The castellation wiring 150 can be formed by making a notch in the second substrate 30 and depositing a film of the same material as the metal film portions 180a, 180b in the notch.

[0019] As described above, the first substrate 20 and the second substrate 30 are bonded together by bonding the second surface 50 of the first substrate 20 to the first surface 160 of the second substrate 30, thereby constituting the base 10. This bonding is achieved by intermetallic bonding between the grounding metal film portion 120a and the oscillation metal film portion 120b of the first substrate and the grounding metal film portion 180a and the oscillation metal film portion 180b of the second substrate. This intermetallic bonding has the advantage that the via wiring portion is sealed with metal, eliminating the problem of reduced airtightness caused by via wiring. The metal film constituting each of the above-mentioned metal film portions is preferably, but not limited to, a laminated film of a chromium film and a gold film stacked in order from the substrate. Furthermore, as described above, the metal film portions 180a and 180b provided on the first surface of the second substrate 30 are connected to the external connection terminals 90a and 90b by the castellation wiring 150, so the second substrate 30 has a structure without via holes, which also has the advantage that the problem of reduced airtightness caused by via wiring does not occur.

[0020] In this embodiment, the first surface 40 of the first substrate 20 is structured to have a metallized pattern 80 along the edge for joining a lid member. As will be described later, this is for joining a cap-shaped lid member 230 (see FIG. 4).

[0021] The first surface 40 of the first substrate 20 may have a bank portion 270 along its edge, and the area surrounded by the bank portion may have a cavity structure in which a quartz crystal blank is mounted. This is because, as will be explained later with reference to FIG. 5, this allows the quartz crystal resonator 250 of the second embodiment to be configured.

[0022] 2.Crystal resonator Next, a crystal resonator using the base 10 of the embodiment will be described. Fig. 4(A) is a perspective view showing an outline of a quartz crystal resonator 210 according to a first embodiment of the present invention, and Fig. 4(B) is a cross-sectional view taken along CC in Fig. 4(A). The quartz crystal unit 210 of the first embodiment of the present invention is characterized by comprising a base 10 having a metallized pattern 81 for joining a lid member along the edge of the first surface 41 of the first substrate 21, a quartz crystal blank 220 mounted on a mounting pad 61 of the base 10, and a lid member 230 having a recess 240 for sealing the quartz crystal blank 220.

[0023] Fig. 5(A) is a perspective view showing an overview of a quartz crystal resonator 250 according to a second embodiment of the present invention, and Fig. 5(B) is a cross-sectional view taken along line BB in Fig. 5(A). The crystal unit 250 of the second embodiment of the present invention is characterized by comprising a base 10 in which the first surface 42 of the first substrate 22 has a bank portion 270 along its edge, and a recess 260 surrounded by the bank portion forms a cavity for mounting a crystal blank 221, a crystal blank 221 mounted on a mounting pad 62 of the base 10, and a lid 280 that seals the crystal blank.

[0024] The crystal resonators of the first and second embodiments each have a base that is suited to the respective embodiment, and since these bases have a built-in capacitor, the mounting area for mounting the capacitor can be reduced. Furthermore, since the base is made of glass and crystal material, it can be processed using photolithography technology and can be processed with relatively high precision. In addition, since the material costs for both are relatively low, it is possible to achieve cost reductions. [Explanation of symbols]

[0025] 10: Base of the embodiment of the present invention 20: First substrate 21: A first substrate constituting a base used in the crystal resonator according to the first embodiment of the present invention 22: A first substrate constituting a base used in a crystal resonator according to a second embodiment of the present invention 30: Second board 31: A second substrate constituting a base used in the crystal resonator according to the first embodiment of the present invention 32: A second substrate constituting a base used in a crystal resonator according to a second embodiment of the present invention 40, 41, 42: First surface of first substrate 50: Second surface of first board 60, 61, 62: Mounting pads for mounting crystal blank 70a, 71a, 72a: Beer holes 70b, 71b, 72b: Via hole wiring 80, 81, 82: Metallized pattern 90(a, b) 91(a, b), 92(a, b): External connection terminals 100, 101, 102: recesses 110, 111, 112: Input or output capacitors 120(a, b): Metal film portion on the second surface of the first substrate 130: Insulating portion on the second surface of the first substrate 140, 141, 142: Mounting pads for capacitors 150, 151, 152: Castellated wiring 160: First surface of second substrate 170: Second surface of second substrate 180(a, b): Metal film portion on the first surface of the second substrate 190: Insulating portion on the first surface of the second substrate 200: Insulating portion on the second surface of the second substrate 210: Crystal unit according to the first embodiment of the present invention 220: Crystal piece 221: Crystal piece 230: Lid member 240: Recessed portion of lid member 250: A quartz crystal resonator according to a second embodiment of the present invention 260: Recessed portion of the first substrate constituting the base used in the crystal unit of the second embodiment 270: Bank 280: Lid

Claims

1. a second substrate made of the same material as the first substrate and bonded to the first substrate on a second surface opposite to the first surface; at least one recess provided in the first substrate and the second substrate, recessed to a predetermined depth from a bonding interface between the first substrate and the second substrate on both or one of the first and second substrates; two capacitors provided in the recess and used as an input capacitor and an output capacitor of the crystal oscillator, the two capacitors being built into the base; external connection terminals provided on a second surface of the second substrate opposite to the first substrate, for connecting the base to an external device; and wiring connecting the pads, the external connection terminals, and the two capacitors; the first substrate and the second substrate are joined by metal-to-metal bonding; the recess is recessed only from the bonding interface toward the first substrate, A base characterized in that a mounting pad for mounting the capacitor is provided on a first surface of the second substrate, which is the surface of the second substrate facing the first substrate, and the mounting pad is composed of a part of the metal film for metal-to-metal bonding.

2. the pad and the two capacitors are connected by via wiring provided on the first substrate and a metal film used for the metal-to-metal junction; the pad and the external connection terminal are connected by the via wiring, the metal film used for the metal-to-metal junction, and the castellation wiring; The base according to claim 1 , wherein the via wiring is sealed by the metal film for intermetallic bonding.

3. 3. The base according to claim 1, further comprising a metallized pattern for joining a lid member along an edge of the first surface of the first substrate.

4. A base as described in any one of claims 1 to 3, characterized in that it has a bank portion along the edge of the first surface of the first substrate, and the area surrounded by the bank portion forms a cavity in which a quartz piece is mounted.

5. A base according to any one of claims 1 to 4, a crystal blank fixed to the pad; a cover member bonded to the base and sealing the crystal piece; A quartz crystal resonator comprising:

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