Crystal oscillator, electronic component, and electronic device

Abstract

The crystal oscillator (1) includes: a crystal vibration element (10) having excitation electrodes (14a, 14b) and connection electrodes (16a, 16b) electrically connected to the excitation electrodes (14a, 14b), a base member (30) having electrode pads (33a, 33b), conductive holding members (36a, 36b) connecting the connection electrodes (16a, 16b) to the electrode pads (33a, 33b), and a lid member (20) forming an internal space (26) for accommodating the crystal vibration element (10) between the lid member (20) and the base member (30); the conductive holding members (36a, 36b) are cured products of a conductive adhesive mainly composed of a silicone resin, and the conductive adhesive contains an epoxy compound having two or more epoxy groups.

Description

Technical Field

[0001] The present invention relates to a crystal oscillator, an electronic component, and an electronic device. Background Art

[0002] Piezoelectric oscillators are used in various electronic devices such as mobile communication terminals, communication base stations, and household appliances for timekeeping devices, sensors, oscillators, and the like. For example, a piezoelectric oscillator includes a piezoelectric vibration element having a mechanical vibration portion that converts electrical vibration into mechanical vibration using the piezoelectric effect, a holder that houses the piezoelectric vibration element, and a conductive holding member that connects the piezoelectric vibration element and the holder. The conductive holding member is, for example, a cured product of a conductive adhesive mainly composed of epoxy resin.

[0003] Patent Document 1 discloses a conductive adhesive containing an epoxy resin, a curing agent, and a conductive material, and the epoxy resin contains 5 to 60% by weight of glycidyl group-containing siloxane.

[0004] Patent Document 2 discloses a conductive adhesive characterized by containing an epoxy resin in which 20 to 70% by weight is a glycidyl group type reactive diluent material, a phenolic resin curing agent in which 50% by weight or more is an alkyl resole type phenolic resin and / or an alkyl novolak type phenolic resin, and conductive particles.

[0005] Patent Document 3 discloses a crystal oscillator characterized by bonding and fixing one end of a lead conductor of a peripheral device to a metal electrode provided on a crystal piece using a conductive adhesive, and the conductive adhesive contains an organic resin having two or more carboxyl groups in a molecular side chain or a molecular end, an epoxy compound having an alicyclic epoxy group and a glycidyl group in the same molecule, and conductive powder as essential components.

[0006] Prior Art Documents

[0007] Patent Documents

[0008] Patent Document 1: Japanese Patent Laid-Open No. 59-172571

[0009] Patent Document 2: Japanese Patent Laid-Open No. 9-157613

[0010] Patent Document 3: Japanese Patent Laid-Open No. 2-180975 Summary of the Invention

[0011] In recent years, as a conductive holding member for connecting a crystal vibration element and a holder, research has been conducted to improve the frequency-temperature characteristics by using a cured product of a silicone-based conductive adhesive mainly composed of silicone resin. However, when using a cured product of a resin-based adhesive as a joining member for connecting a base member and a lid member that constitute a holder, if a cured product of a silicone-based conductive adhesive is used as the conductive holding member, there is a problem that the resistance value deteriorates in a high-humidity environment.

[0012] The present invention has been made in view of such circumstances, and an object thereof is to provide a crystal oscillator, an electronic component, and an electronic device with improved reliability.

[0013] A crystal oscillator according to one embodiment of the present invention includes: a crystal vibration element having an exciting electrode and a connection electrode electrically connected to the exciting electrode; a base member having an electrode pad; a conductive holding member connecting the connection electrode and the electrode pad; and a lid member forming an internal space for accommodating the crystal vibration element between the base member; the conductive holding member is a cured product of a conductive adhesive mainly composed of silicone resin, and the conductive adhesive contains an epoxy compound having two or more epoxy groups.

[0014] An electronic device according to one embodiment of the present invention includes: an electronic component; a substrate having a metal layer; and a conductive bonding portion connecting the electronic component and the metal layer of the substrate; the conductive bonding portion is a cured product of a conductive adhesive mainly composed of silicone resin, and the conductive adhesive contains an epoxy compound having two or more epoxy groups.

[0015] An electronic component according to one embodiment of the present invention includes: a first adherend having conductivity; a second adherend having conductivity; and a conductive bonding portion connecting the first adherend and the second adherend; the conductive bonding portion is a cured product of a conductive adhesive mainly composed of silicone resin, and the conductive adhesive contains an epoxy compound having two or more epoxy groups.

[0016] According to the present invention, it is possible to provide a crystal oscillator, an electronic component, and an electronic device with improved reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is an exploded perspective view schematically showing the configuration of a crystal oscillator according to the first embodiment.

[0018] Figure 2 is a cross-sectional view schematically showing the configuration of a crystal oscillator according to the first embodiment.

[0019] Figure 3 is a diagram showing the structural formula of an epoxy compound added to the conductive adhesive.

[0020] Figure 4 It is a top view schematically showing the structure of a substrate for evaluating a moisture resistance test.

[0021] Figure 5 It is a cross-sectional view schematically showing the structure of a substrate for evaluating a moisture resistance test.

[0022] Figure 6 It is a figure schematically showing the evaluation results of an example.

[0023] Figure 7 It is a figure schematically showing the evaluation results of a comparative example.

[0024] Figure 8 It is a cross-sectional view schematically showing the configuration of an electronic device according to a second embodiment.

[0025] Figure 9 It is a figure showing the evaluation results of moisture resistance when the content rate of the epoxy compound is 0 wt%.

[0026] Figure 10 It is a figure showing the evaluation results of moisture resistance when the content rate of the epoxy compound is 0.1 wt%.

[0027] Figure 11 It is a figure showing the evaluation results of moisture resistance when the content rate of the epoxy compound is 0.5 wt%.

[0028] Figure 12 It is a figure showing the evaluation results of moisture resistance when the content rate of the epoxy compound is 1 wt%.

[0029] Figure 13 It is a figure showing the evaluation results of moisture resistance when the content rate of the epoxy compound is 5 wt%.

[0030] Figure 14 It is a figure showing the evaluation results of moisture resistance when the content rate of the epoxy compound is 10 wt%.

[0031] Figure 15 It is a figure showing the structural formula of the epoxy compound added in the first modification example.

[0032] Figure 16 It is a figure showing the evaluation results of moisture resistance in the first modification example.

[0033] Figure 17 It is a figure showing the structural formula of the epoxy compound added in the second modification example.

[0034] Figure 18 It is a figure showing the evaluation results of moisture resistance in the second modification example.

[0035] Figure 19This is a diagram showing the structural formula of the epoxy compound added in the third modification example.

[0036] Figure 20 This is a diagram showing the evaluation results of moisture resistance in the third modification example.

[0037] Figure 21 This is a diagram showing the structural formula of the epoxy compound added in the fourth modification example.

[0038] Figure 22 This is a diagram showing the evaluation results of moisture resistance in the fourth modification example. Detailed Implementation Modes

[0039] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The drawings of each embodiment are illustrative, and the dimensions and shapes of each part are schematic. The technical scope of the claimed invention should not be construed as being limited to this embodiment.

[0040] <First Embodiment>

[0041] Refer to Figures 1 to 3 The configuration of the crystal oscillator 1 according to the first embodiment of the present invention will be described. Figure 1 This is an exploded perspective view schematically showing the configuration of the crystal oscillator according to the first embodiment. Figure 2 This is a cross-sectional view schematically showing the configuration of the crystal oscillator according to the first embodiment. Figure 3 This is a diagram showing the structural formula of the epoxy compound added to the conductive adhesive. It should be noted that Figure 2 The cross-sectional view shown in Figure 1 shows the cross-section of the crystal oscillator 1 along the line II-II shown in

[0042] In each of the drawings, in order to clarify the relationship between the respective drawings, assist in understanding the positional relationship of each component, and for convenience, an orthogonal coordinate system composed of the X-axis, Y'-axis, and Z'-axis is provided. The X-axis, Y'-axis, and Z'-axis correspond to each other in each drawing. The X-axis, Y'-axis, and Z'-axis respectively correspond to the crystallographic axes of the crystal wafer 11 described later. The X-axis corresponds to the electrical axis (polar axis), the Y-axis corresponds to the mechanical axis, and the Z-axis corresponds to the optical axis. The Y'-axis and Z'-axis are axes obtained by rotating the Y-axis and Z-axis around the X-axis by 35 degrees 15 minutes ± 1 minute 30 seconds from the Y-axis in the direction of the Z-axis.

[0043] In the following description, the direction parallel to the X-axis is referred to as the "X-axis direction", the direction parallel to the Y'-axis is referred to as the "Y'-axis direction", and the direction parallel to the Z'-axis is referred to as the "Z'-axis direction". In addition, the front end direction of the arrows of the X-axis, Y'-axis, and Z'-axis is referred to as "+", and the direction opposite to the arrow is referred to as "-". It should be noted that for convenience, the +Y'-axis direction is taken as the upward direction and the -Y'-axis direction is taken as the downward direction for the description, but the up and down orientations of the crystal oscillator 1 are not limited. For example, in the following description, the +Y'-axis direction side of the crystal vibration element 10 is taken as the upper surface 11A, and the -Y'-axis direction side is taken as the lower surface 11B, but the crystal oscillator 1 can be arranged such that the upper surface 11A is vertically below the lower surface 11B.

[0044] The crystal oscillator 1 includes a crystal vibration element 10, a base member 30, a cover member 40, and a joining member 50. The crystal vibration element 10 is disposed between the base member 30 and the cover member 40. The base member 30 and the cover member 40 constitute a holder for accommodating the crystal vibration element 10. Figure 1 and Figure 2 In the example shown in, the base member 30 is formed in a flat plate shape, and the cover member 40 has a bottomed opening for accommodating the crystal vibration element 10 on the side of the base member 30. Moreover, the crystal vibration element 10 is mounted on the base member 30. It should be noted that as long as at least the excited portion of the crystal vibration element 10 is accommodated in the holder, the shapes of the base member 30 and the cover member 40 are not limited to the above. In addition, the holding method of the crystal vibration element 10 is not limited to the above. For example, the base member 30 may have a bottomed opening for accommodating the crystal vibration element 10 on the side of the cover member 40. In addition, the base member 30 and the cover member 40 may sandwich the peripheral portion of the excited portion of the crystal vibration element 10.

[0045] First, the crystal vibration element 10 will be described.

[0046] The crystal vibration element 10 is an element that converts electrical energy and mechanical energy by vibrating a crystal through the piezoelectric effect. The crystal vibration element 10 includes: a thin crystal plate 11, a first excitation electrode 14a and a second excitation electrode 14b that constitute a pair of excitation electrodes, a first lead electrode 15a and a second lead electrode 15b that constitute a pair of lead electrodes, and a first connection electrode 16a and a second connection electrode 16b that constitute a pair of connection electrodes.

[0047] The crystal plate 11 has an upper surface 11A and a lower surface 11B that face each other. The upper surface 11A is on the side opposite to the side facing the base member 30, that is, on the side facing the top surface 41 of the cover member 40 to be described later. The lower surface 11B is on the side facing the base member 30.

[0048] The crystal wafer 11 is, for example, an AT-cut type crystal wafer. The AT-cut type crystal wafer 11 is formed such that in an orthogonal coordinate system composed of mutually intersecting X-axis, Y'-axis, and Z'-axis, the plane parallel to the plane determined by the X-axis and Z'-axis (hereinafter, referred to as "XZ' plane"; the same applies to the planes determined by other axes) is the main plane, and the direction parallel to the Y'-axis is the thickness. For example, the AT-cut type crystal wafer 11 is formed by etching a crystal substrate (e.g., a crystal wafer), which is obtained by cutting and grinding a crystal of synthetic quartz crystal.

[0049] The crystal oscillator element 10 using the AT-cut type crystal wafer 11 has high frequency stability in a wide temperature range. In the AT-cut type crystal oscillator element 10, the thickness shear vibration mode is used as the main vibration. It should be noted that the rotation angles of the Y'-axis and Z'-axis in the AT-cut type crystal wafer 11 can be inclined in the range from 35 degrees 15 minutes to -5 degrees or more and 15 degrees or less. The cutting angle of the crystal wafer 11 can be different from AT-cut, such as BT-cut, GT-cut, SC-cut, etc. In addition, the crystal oscillator element can also be a tuning fork type crystal oscillator element using a crystal wafer with a cutting angle, which is called a Z-plate.

[0050] The AT-cut type crystal wafer 11 is plate-shaped with a long side direction in which the long side extends parallel to the X-axis direction, a short side direction in which the short side extends parallel to the Z'-axis direction, and a thickness direction in which the thickness extends parallel to the Y'-axis direction. When the upper surface 11A is viewed from above, the crystal wafer 11 has a rectangular shape, and has an excitation portion 17 located in the center and contributing to excitation, and peripheral portions 18, 19 adjacent to the excitation portion 17. The excitation portion 17 and the peripheral portions 18, 19 are each formed in a strip shape over the entire width along the Z'-axis direction of the crystal wafer 11. The peripheral portion 18 is located on the -X-axis direction side of the excitation portion 17, and the peripheral portion 19 is located on the +X-axis direction side of the excitation portion 17.

[0051] It should be noted that the planar shape of the crystal wafer 11 when the upper surface 11A is viewed from above is not limited to a rectangular shape. The planar shape of the crystal wafer 11 can also be a polygonal shape, a circular shape, an elliptical shape, or a combination thereof. The planar shape of the crystal wafer 11 can also be a tuning fork shape having a base portion and vibration arm portions extending parallel from the base portion. In order to suppress vibration leakage and stress propagation, slits can be formed in the crystal wafer 11. The shapes of the excitation portion 17 and the peripheral portions 18, 19 of the crystal wafer 11 are not limited to strip shapes over the entire width. For example, the planar shape of the excitation portion can also be an island shape adjacent to the peripheral portion in the Z'-axis direction, and the planar shape of the peripheral portion can also be formed in a frame shape surrounding the excitation portion.

[0052] The crystal piece 11 has a so-called mesa structure in which the thickness of the excitation portion 17 is greater than that of the peripheral portions 18 and 19. With the crystal piece 11 having a mesa structure, vibration leakage from the excitation portion 17 can be suppressed. The crystal piece 11 has a double-sided mesa structure, and on both sides of the upper surface 11A and the lower surface 11B, the excitation portion 17 protrudes from the peripheral portions 18 and 19. The boundary between the excitation portion 17 and the peripheral portion 18 and the boundary between the excitation portion 17 and the peripheral portion 19 form a tapered shape in which the thickness changes continuously, but a stepped shape in which the thickness change is discontinuous may also be formed. This boundary may also be a convex shape in which the amount of thickness change changes continuously or a chamfered shape in which the amount of thickness change changes discontinuously. It should be noted that the crystal piece 11 may also be a single-sided mesa structure in which the excitation portion 17 protrudes from the peripheral portions 18 and 19 on one side of the upper surface 11A or the lower surface 11B. In addition, the crystal piece 11 may also be a so-called inverted mesa structure in which the thickness of the excitation portion 17 is smaller than that of the peripheral portions 18 and 19.

[0053] The first excitation electrode 14a and the second excitation electrode 14b are provided on the excitation portion 17. The first excitation electrode 14a is provided on the upper surface 11A side of the crystal piece 11, and the second excitation electrode 14b is provided on the lower surface 11B side of the crystal piece 11. In other words, the first excitation electrode 14a is provided on the main surface of the crystal piece 11 on the side of the lid member 40, and the second excitation electrode 14b is provided on the main surface of the crystal piece 11 on the side of the base member 30. The first excitation electrode 14a and the second excitation electrode 14b are opposed to each other with the crystal piece 11 interposed therebetween. When looking down at the upper surface 11A of the crystal piece 11, the first excitation electrode 14a and the second excitation electrode 14b each form a rectangular shape and are arranged so as to substantially entirely overlap each other. The first excitation electrode 14a and the second excitation electrode 14b are each formed in a strip shape over the entire width in the Z' axis direction of the crystal piece 11.

[0054] It should be noted that the planar shapes of the first excitation electrode 14a and the second excitation electrode 14b when looking down at the upper surface 11A of the crystal piece 11 are not limited to rectangular shapes. The planar shapes of the first excitation electrode 14a and the second excitation electrode 14b may also be polygonal shapes, circular shapes, elliptical shapes, or combinations thereof.

[0055] The first lead-out electrode 15a and the second lead-out electrode 15b are provided on the peripheral portion 18. The first lead-out electrode 15a is provided on the upper surface 11A side of the crystal piece 11, and the second lead-out electrode 15b is provided on the lower surface 11B side of the crystal piece 11. The first lead-out electrode 15a electrically connects the first excitation electrode 14a and the first connection electrode 16a. The second lead-out electrode 15b electrically connects the second excitation electrode 14b and the second connection electrode 16b. For example, as Figure 1As shown, one end of the first lead electrode 15a is connected to the first excitation electrode 14a in the excitation portion 17, and the other end is connected to the first connection electrode 16a in the peripheral portion 18 via a side electrode provided on a side surface connecting the upper surface 11A and the lower surface 11B of the crystal piece 11. Further, one end of the second lead electrode 15b is connected to the second excitation electrode 14b in the excitation portion 17, and the other end is connected to the second connection electrode 16b in the peripheral portion 18 via the side electrode. In order to reduce stray capacitance, the first lead electrode 15a and the second lead electrode 15b are preferably separated from each other when looking down at the upper surface 11A of the crystal piece 11. For example, when viewed from the second lead electrode 15b, the first lead electrode 15a is provided in the +Z' axis direction.

[0056] The first connection electrode 16a and the second connection electrode 16b are electrodes for electrically connecting the first excitation electrode 14a and the second excitation electrode 14b to the base member 30, and are provided on the lower surface 11B side of the crystal piece 11 in the peripheral portion 18. The first connection electrode 16a is provided at a corner formed by the end on the -X axis direction side and the end on the +Z' axis direction side of the crystal piece 11, and the second connection electrode 16b is provided at a corner formed by the end on the -X axis direction side and the end on the -Z' axis direction side of the crystal piece 11.

[0057] The first excitation electrode 14a, the first lead electrode 15a, and the first connection electrode 16a are integrally formed, and the second excitation electrode 14b, the second lead electrode 15b, and the second connection electrode 16b are integrally formed. Various electrodes of the crystal vibration element 10 (the first excitation electrode 14a and the second excitation electrode 14b, the first lead electrode 15a and the second lead electrode 15b, the first connection electrode 16a and the second connection electrode 16b) are provided by laminating chromium (Cr) and gold (Au) in this order, for example. Chromium is superior to gold in terms of adhesion to the crystal piece 11, and gold is superior to chromium in terms of chemical stability. Therefore, when chromium is contained in the lowermost surface in contact with the crystal piece 11 and gold is contained in the outermost surface exposed in the internal space 49, damage to the crystal vibration element 10 due to peeling of various electrodes and change in conductivity due to oxidation can be suppressed, and a highly reliable crystal vibration element 10 can be provided. The outermost surface of various electrodes of the crystal vibration element 10 is preferably composed substantially only of gold. It should be noted that the outermost surface of each of the first connection electrode 16a and the second connection electrode 16b corresponds to a contact surface having a region in contact with the first conductivity holding member 36a and the second conductivity holding member 36b, respectively. On the side surface connecting the lowermost surface and the outermost surface of various electrodes of the crystal vibration element 10, a layer containing chromium and a layer containing gold are exposed.

[0058] Next, the base member 30 will be described.

[0059] The base member 30 vibrates the crystal element 10 so as to be able to excite the crystal element 10. The base member 30 includes a base body 31 having an upper surface 31A and a lower surface 31B that face each other. The upper surface 31A is on the side of the crystal element 10 and the cover member 40, and corresponds to the mounting surface for mounting the crystal element 10. The lower surface 31B corresponds to, for example, the mounting surface for bonding to an external circuit board (not shown). The base body 31 is a sintered material such as insulating ceramics (aluminum oxide), for example. From the viewpoint of suppressing the generation of thermal stress, the base body 31 is preferably made of a heat-resistant material. From the viewpoint of suppressing the stress applied to the crystal element 10 due to thermal history, the base body 31 can be made of a material having a thermal expansion rate close to that of the crystal wafer 11, and can be made of crystal, for example.

[0060] The base member 30 includes a first electrode pad 33a and a second electrode pad 33b that constitute a pair of electrode pads. The first electrode pad 33a and the second electrode pad 33b are provided on the upper surface 31A of the base body 31. The first electrode pad 33a and the second electrode pad 33b are terminals for electrically connecting the crystal element 10 to the base member 30. From the viewpoint of suppressing the reduction in reliability due to oxidation, the outermost surface of each of the first electrode pad 33a and the second electrode pad 33b preferably contains gold, and more preferably consists essentially of gold. For example, the first electrode pad 33a and the second electrode pad 33b can have a two-layer structure including a base layer that improves the adhesion to the base body 31 and a surface layer that contains gold to suppress oxidation. It should be noted that the outermost surface of each of the first electrode pad 33a and the second electrode pad 33b corresponds to the contact surface having a region that contacts the first conductivity holding member 36a and the second conductivity holding member 36b, respectively.

[0061] The base member 30 includes a first external electrode 35a, a second external electrode 35b, a third external electrode 35c, and a fourth external electrode 35d. The first external electrode 35a to the fourth external electrode 35d are provided on the lower surface 31B of the base body 31. The first external electrode 35a and the second external electrode 35b are terminals for electrically connecting an external substrate (not shown) to the crystal oscillator 1. The third external electrode 35c and the fourth external electrode 35d are dummy electrodes that do not input or output electrical signals, etc., but can also be ground electrodes for grounding the cover member 40 to improve the electromagnetic shielding function of the cover member 40. It should be noted that the third external electrode 35c and the fourth external electrode 35d can be omitted.

[0062] The first electrode pad 33a and the second electrode pad 33b are arranged along the Z'-axis direction at the end on the -X-axis direction side of the base member 30. The first external electrode 35a and the second external electrode 35b are arranged along the Z'-axis direction at the end on the -X-axis direction side of the base member 30. The third external electrode 35c and the fourth external electrode 35d are arranged along the Z'-axis direction at the end on the +X-axis direction side of the base member 30. The first electrode pad 33a is electrically connected to the first external electrode 35a through the first through electrode 34a penetrating the base body 31 along the Y'-axis direction. The second electrode pad 33b is electrically connected to the second external electrode 35b through the second through electrode 34b penetrating the base body 31 along the Y'-axis direction.

[0063] The first electrode pad 33a and the second electrode pad 33b can be respectively electrically connected to the first external electrode 35a and the second external electrode 35b through side electrodes provided on the side surface connecting the upper surface 31A and the lower surface 31B of the base body 31. The first external electrode 35a to the fourth external electrode 35d can be tooth-shaped electrodes recessed on the side surface of the base body 31.

[0064] The base member 30 includes a first conductive holding member 36a and a second conductive holding member 36b that constitute a pair of conductive holding members. The first conductive holding member 36a and the second conductive holding member 36b mount the crystal vibration element 10 on the base member 30 and electrically connect the crystal vibration element 10 to the base member 30. The first conductive holding member 36a is joined to the first electrode pad 33a and the first connection electrode 16a to electrically connect the first electrode pad 33a to the first connection electrode 16a. The second conductive holding member 36b is joined to the second electrode pad 33b and the second connection electrode 16b to electrically connect the second electrode pad 33b to the second connection electrode 16b. The first conductive holding member 36a and the second conductive holding member 36b hold the crystal vibration element 10 at an interval from the base member 30 so that the excitation unit 17 can be excited.

[0065] The first conductivity maintaining member 36a and the second conductivity maintaining member 36b are cured products of a conductive adhesive containing a thermosetting resin, a photocurable resin, etc., and the main component of the first conductivity maintaining member 36a and the second conductivity maintaining member 36b is a silicone resin. The first conductivity maintaining member 36a and the second conductivity maintaining member 36b contain conductive particles, and as such conductive particles, for example, metal particles containing silver (Ag) can be used. The first conductivity maintaining member 36a bonds the first electrode pad 33a to the first connection electrode 16a, and the second conductivity maintaining member 36b bonds the second electrode pad 33b to the second connection electrode 16b. The elastic modulus of the silicone resin is more stable than that of the epoxy resin in a wide temperature range. By making the main component of the first conductivity maintaining member 36a and the second conductivity maintaining member 36b a silicone resin, the frequency-temperature characteristics of the crystal vibration element 10 are improved compared with the case where the main component is an epoxy resin.

[0066] The conductive adhesive contains an epoxy compound having two or more glycidyl groups. In the present embodiment, the epoxy compound contained in the conductive adhesive is Figure 3 1,3-bis(3-glycidyloxypropyl)-1,1,3,3-tetramethyldisiloxane shown. The content rate of 1,3-bis(3-glycidyloxypropyl)-1,1,3,3-tetramethyldisiloxane in the conductive adhesive is, for example, 1% by weight. Thereby, the moisture resistance of the first conductivity maintaining member 36a and the second conductivity maintaining member 36b is improved. The improvement in moisture resistance here means suppressing the rise in the contact resistance between the cured product of the conductive adhesive and the adherend in a high-humidity environment.

[0067] It should be noted that the epoxy compound contained in the conductive adhesive is not limited to the above, and any epoxy compound having two or more epoxy groups is acceptable. Among them, in order to improve the moisture resistance, an epoxy compound having two or more glycidyl groups is preferred. In addition, the content rate of the epoxy compound in the conductive adhesive is not limited to 1% by weight, but in order to improve the moisture resistance, it is preferably 0.1% by weight or more. The epoxy compound contained in the conductive adhesive is preferably a silicone compound, and more preferably an epoxy compound having a siloxane bond. For example, the epoxy compound may be an oligomer or polymer having 1,3-bis(3-glycidoxypropyl)-1,1,3,3-tetramethyldisiloxane as a constituent unit. It should be noted that the component weight ratio of the conductive adhesive is, for example, 60% by weight of conductive particles, 20% by weight of silicone resin composition, and 20% by weight of solvent. The epoxy compound having two or more glycidyl groups is contained in the silicone resin composition, and the content rate of the epoxy compound is the ratio of the weight of the epoxy compound to the total weight of the conductive adhesive. That is, in the case where the conductive adhesive is composed of conductive particles, silicone resin composition, and solvent, the content rate of the epoxy compound is the ratio of the weight of the epoxy compound to the sum of the weights of the conductive particles, silicone resin composition, and solvent respectively.

[0068] In addition to silanes or siloxanes, conductive particles, and epoxy compounds having two or more epoxy groups which are raw materials for the silicone resin, the conductive adhesive may further contain additives. Additives are, for example, thickeners, fillers, thickeners, sensitizers, anti-aging agents, defoamers, etc. for the purpose of improving the workability, storage stability, etc. of the conductive adhesive. In addition, in order to increase the strength of the cured product, or to maintain the interval between the base member 30 and the crystal vibration element 10, a filler may also be added.

[0069] The process of providing the first conductive holding member 36a and the second conductive holding member 36b, for example, has: a coating process of coating the conductive adhesive made into a paste by adjusting the viscosity on the first electrode pad 33a and the second electrode pad 33b, a placing process of placing the crystal vibration element 10 on the conductive adhesive and supporting the crystal vibration element 10 by the conductive adhesive that has wetted and spread on the surfaces of the first connection electrode 16a and the second connection electrode 16b, and a curing process of curing the conductive adhesive. It should be noted that the process of providing the first conductive holding member 36a and the second conductive holding member 36b may have a temporary curing process of incompletely curing the conductive adhesive before or after the placing process. Thereby, it is possible to suppress the contact between the crystal vibration element 10 and the base member 30 caused by the posture collapse of the crystal vibration element 10 before the curing process.

[0070] Next, the lid member 40 will be described.

[0071] The cover member 40 is joined to the base member 30 to form an internal space 49 for accommodating the crystal vibration element 10 therebetween. The material of the cover member 40 is not particularly limited and is made of, for example, a conductive material such as metal. Since the cover member 40 is made of a conductive material, an electromagnetic shielding function for reducing the entry and exit of electromagnetic waves into and out of the internal space 49 is imparted to the cover member 40.

[0072] The cover member 40 has a flat top surface portion 41 and a side wall portion 42 connected to the outer edge of the top surface portion 41 and extending in a direction intersecting the main surface of the top surface portion 41. The planar shape of the top surface portion 41 when viewed from the normal direction of the main surface is, for example, a rectangular shape. The top surface portion 41 faces the base member 30 with the crystal vibration element 10 interposed therebetween, and the side wall portion 42 surrounds the periphery of the crystal vibration element 10 in a direction parallel to the XZ' plane. The front end of the side wall portion 42 extends in a frame shape closer to the base member 30 side than the crystal vibration element 10.

[0073] The cover member 40 can be made of a ceramic material, a semiconductor material, a resin material, etc. In addition, the planar shape of the top surface portion 41 can be a polygonal shape, a circular shape, an elliptical shape, or a combination thereof.

[0074] Next, the joining member 50 will be described.

[0075] The joining member 50 is provided over the entire circumferences of the base member 30 and the cover member 40 to form a rectangular frame shape. When looking down at the upper surface 31A of the base member 30, the first electrode pad 33a and the second electrode pad 33b are disposed inside the joining member 50, and the joining member 50 is provided to surround the crystal vibration element 10. The joining member 50 joins the front end of the side wall portion 42 of the cover member 40 to the upper surface 31A of the base 31 of the base member 30 to seal the internal space 49. The joining member 50 preferably has high gas barrier properties, and more preferably has low moisture permeability. Such a joining member 50 is, for example, a cured product of an adhesive mainly composed of epoxy resin. The resin-based adhesive constituting the joining member 50 can contain, for example, a vinyl compound, an acrylic compound, a urethane compound, a silicone compound, etc.

[0076] It should be noted that the joining member 50 is not limited to a continuously formed frame shape in the circumferential direction and can also be provided discontinuously in the circumferential direction. The joining member 50 can be made of a cured product of a silicon-based adhesive containing sodium silicate, etc., a cured product of a calcium-based adhesive containing cement, etc., a metal solder of an Au - Sn alloy system, etc. When the joining member 50 is made of a metal solder, a metallization layer can be provided on the base member 30 to improve the adhesion between the base member 30 and the joining member 50. The joining member 50 can have a cured product of a resin-based adhesive and a coating having lower moisture permeability than the cured product of the resin-based adhesive.

[0077] (Moisture resistance evaluation)

[0078] Refer to Figures 4 to 7 , and describe the moisture resistance test for investigating the influence of moisture on the conductivity between the metal electrode and the cured product of the conductive adhesive. Figure 4 It is a top view schematically showing the structure of the evaluation substrate for the moisture resistance test. Figure 5 It is a cross-sectional view schematically showing the structure of the evaluation substrate for the moisture resistance test. Figure 6 It is a diagram schematically showing the evaluation results of the examples. Figure 7 It is a diagram schematically showing the evaluation results of the comparative examples. Figure 6 and Figure 7 In the diagrams of

[0079] As Figure 4 shown, on the evaluation substrate B10, the first electrode pair E10, the second electrode pair E20, the third electrode pair E30, the fourth electrode pair E40, and the fifth electrode pair E50 are arranged in sequence. The first electrode pair E10 to the fifth electrode pair E50 are provided on the insulating substrate. The first electrode pair E10 has a pair of measurement electrodes E11, E12 and a bridge electrode E13 connecting the measurement electrode E11 and the measurement electrode E12. Similarly, the second electrode pair E20 has a pair of measurement electrodes E21, E22 and a bridge electrode E23, the third electrode pair E30 has a pair of measurement electrodes E31, E32 and a bridge electrode E33, the fourth electrode pair E40 has a pair of measurement electrodes E41, E42 and a bridge electrode E43, and the fifth electrode pair E50 has a pair of measurement electrodes E51, E52 and a bridge electrode E53. The central portions E1, E2, E3, E4, E5 of the bridge electrodes E13 to E53 are covered by the cured product E9 of the conductive adhesive. The cured product E9 of the conductive adhesive has a substantially uniform width and thickness and extends in the arrangement direction of the first electrode pair E10 to the fifth electrode pair E50. The first electrode pair E10 to the fifth electrode pair E50 are electrically connected by the cured product E9 of the conductive adhesive.

[0080] The insulating substrate is an alumina substrate. The first electrode pair E10 to the fifth electrode pair E50 are metal electrodes having a laminated structure with a base layer made of nickel and a surface layer made of gold. The outermost surface of the first electrode pair E10 to the fifth electrode pair E50 is formed of gold. The cured product E9 of the conductive adhesive is mainly composed of a silicone resin. The conductive adhesive in the example contains 1% of 1,3 - bis(3 - glycidoxypropyl) - 1,1,3,3 - tetramethyldisiloxane. The conductive adhesive in the comparative example is the same as the conductive adhesive in the example except that it does not contain 1,3 - bis(3 - glycidoxypropyl) - 1,1,3,3 - tetramethyldisiloxane.

[0081] AsFigure 5 As shown, the moisture resistance of the cured product E9 of the conductive adhesive is evaluated by measuring the respective changes in the resistance values 1-2 between the central part E1 and the central part E2, the resistance value 1-3 between the central part E1 and the central part E3, the resistance value 1-4 between the central part E1 and the central part E4, and the resistance value 1-5 between the central part E1 and the central part E5. The resistance value 1-2 is determined by the contact resistance between the central part E1 and the cured product E9 of the conductive adhesive, the resistance of the cured product E9 of the conductive adhesive between the central part E1 and the central part E2, and the contact resistance between the cured product E9 of the conductive adhesive and the central part E2. The resistance values 1-3, 1-4, and 1-5 are similarly determined by the resistance of the cured product E9 of the conductive adhesive itself and the contact resistance between the cured product E9 of the conductive adhesive and the central part of the electrode pair.

[0082] In the measurement of the resistance value 1-2, in order to cancel the influence other than the central parts E1, E2 and the cured product E9 of the conductive adhesive, the measurement is carried out as follows.

[0083] The resistance values between the measurement electrode E11 and the measurement electrode E21, the resistance values between the measurement electrode E11 and the measurement electrode E22, the resistance values between the measurement electrode E12 and the measurement electrode E22, and the resistance values between the measurement electrode E12 and the measurement electrode E21 are measured, and the calculated result of the sum is set as A.

[0084] The resistance values between the measurement electrode E11 and the measurement electrode E12 and the resistance values between the measurement electrode E21 and the measurement electrode E22 are measured, and the calculated result of the sum and doubling is set as B.

[0085] Subtract B from A and divide by 4, thereby calculating the resistance value 1-2.

[0086] The resistance values 1-3, 1-4, and 1-5 are similarly calculated.

[0087] As Figure 6 shown, in the examples, in the initial state; in the state after being placed in a constant temperature and humidity chamber at a temperature of 85°C and a humidity of 85RH% (hereinafter referred to as "85°C 85RH%") for 100 hours; and in the state after being placed in 85°C 85RH% for 500 hours, the measurement is carried out. Figure 6 In it, the line graph representing the resistance value in the initial state is depicted as "Initial", the line graph representing the resistance value in the state after being placed for 100 hours is depicted as "After 100h", and the line graph representing the resistance value in the state after being placed for 500 hours is depicted as "After 500h".

[0088] Even in the state after being placed for 500 hours, the resistance values of Resistance Value 1-2, Resistance Value 1-3, Resistance Value 1-4, and Resistance Value 1-5 are all below 1 Ω, and almost no deterioration of the resistance value from the initial state is observed.

[0089] As Figure 7 shown, in the comparative example, the resistance values were measured in the initial state; the state after being placed at 85°C and 85% RH for 150 hours; and the state after being placed at 85°C and 85% RH for 530 hours. Figure 7 Among them, the line graph representing the resistance value in the initial state is depicted as "Initial", the line graph representing the resistance value in the state after being placed for 150 hours is plotted as "After 150h", and the line graph representing the resistance value in the state after being placed for 530 hours is depicted as "After 530h".

[0090] After being placed for 530 hours, the resistance values of Resistance Value 1-3, Resistance Value 1-4, and Resistance Value 1-5 exceed 1 Ω, and deterioration from the initial state is observed. In particular, the resistance value of Resistance Value 1-4 exceeds 4 Ω in the state after being placed for 530 hours. In the state after being placed for 530 hours, the resistance values of Resistance Value 1-3 and Resistance Value 1-5 are greater than that of Resistance Value 1-4. Therefore, it is considered that the main factor for the increase in the resistance value is not the increase in the resistance value of the cured product of the conductive adhesive itself, but the increase in the contact resistance between the cured product of the conductive adhesive and the central part of the electrode pair.

[0091] From the evaluation results of the examples and comparative examples, it can be seen that by containing 1,3-bis(3-glycidyloxypropyl)-1,1,3,3-tetramethyldisiloxane in the resin composition of the conductive adhesive, it is possible to inhibit the increase in the contact resistance between the cured product of the conductive adhesive mainly composed of an organosilicon resin and the metal electrode in a high-humidity environment.

[0092] Next, with reference to Figures 9 to 14 the relationship between the content rate of 1,3-bis(3-glycidyloxypropyl)-1,1,3,3-tetramethyldisiloxane and the moisture resistance of the cured product of the conductive adhesive will be described. Figure 9 is a graph showing the evaluation results of the moisture resistance when the content rate of the epoxy compound is 0 wt%. Figure 10 is a graph showing the evaluation results of the moisture resistance when the content rate of the epoxy compound is 0.1 wt%. Figure 11 is a graph showing the evaluation results of the moisture resistance when the content rate of the epoxy compound is 0.5 wt%. Figure 12 is a graph showing the evaluation results of the moisture resistance when the content rate of the epoxy compound is 1 wt%. Figure 13 is a graph showing the evaluation results of the moisture resistance when the content rate of the epoxy compound is 5 wt%. Figure 14 is a graph showing the evaluation results of the moisture resistance when the content rate of the epoxy compound is 10 wt%.

[0093] The moisture resistance test is carried out in the same way as the evaluation methods of the examples and comparative examples shown in Figures 4 to 7 to measure and compare the change in the resistance value at 85°C and 85% RH. Figures 9 to 14 In this case, "initial" represents the resistance value in the initial state before being put into 85°C and 85% RH, "after 100 h" represents the resistance value after 100 hours at 85°C and 85% RH, "after 500 h" represents the resistance value after 500 hours at 85°C and 85% RH, and "after 1000 h" represents the resistance value after 1000 hours at 85°C and 85% RH. It should be noted that Figure 9 corresponds to the evaluation result of the comparative example, Figure 12 and corresponds to the evaluation result of the example. Regardless of the content rate of 1,3-bis(3-glycidyloxypropyl)-1,1,3,3-tetramethyldisiloxane, the resistance value in the initial state is approximately 0 Ω. Therefore, the resistance values after 100, 500, and 1000 hours respectively correspond to the change amount of the resistance value from the initial state. The larger the change amount of the resistance value, the lower the moisture resistance.

[0094] When the content rate of 1,3-bis(3-glycidyloxypropyl)-1,1,3,3-tetramethyldisiloxane is 0 wt%, that is, in the case of not containing an epoxy compound, the resistance value has already increased after 100 hours, and the maximum increase is about 5.0 Ω after 500 hours, and the maximum exceeds 15.0 Ω after 1000 hours. When the content rate of 1,3-bis(3-glycidyloxypropyl)-1,1,3,3-tetramethyldisiloxane is 0.1 wt%, the resistance value hardly increases after 100 hours, starts to increase after 500 hours, and the maximum increase is about 4.0 Ω after 1000 hours. When the content rate of 1,3-bis(3-glycidyloxypropyl)-1,1,3,3-tetramethyldisiloxane is 0.5 - 10 wt%, the resistance value hardly increases after 1000 hours.

[0095] As described above, it can be seen that the moisture resistance of the cured product of the organosilicon-based conductive adhesive is improved as long as an epoxy compound having two or more epoxy groups is added in an amount of 0.1% by weight or more, and is further improved if added in an amount of 0.5% by weight or more. It should be noted that if an epoxy compound is added to the organosilicon-based conductive adhesive, the viscosity decreases. In particular, when the content rate of the epoxy compound exceeds 10% by weight, the workability deteriorates due to the decrease in viscosity, and the production rate of defective products sometimes increases in the crystal oscillator. Therefore, in order to improve the moisture resistance while maintaining the workability, the content rate of the epoxy compound is preferably 0.1% by weight to 10% by weight, and more preferably 0.5% by weight to 10% by weight. In addition, when the content rate of the epoxy compound exceeds 10% by weight, the characteristics of the organosilicon resin sometimes disappear from the cured product of the conductive adhesive. For example, when the content rate of the epoxy compound exceeds 10% by weight, the temperature change of the elastic modulus of the cured product of the conductive adhesive sometimes becomes large, and the frequency-temperature characteristics of the crystal vibration element 10 deteriorate. Therefore, from the viewpoint of suppressing the deterioration of the frequency-temperature characteristics, the content rate of the epoxy compound is preferably 10% by weight or less.

[0096] Next, with reference to Figures 15 to 22 The moisture resistance of the cured product of the conductive adhesive containing an epoxy compound other than 1,3-bis(3-glycidyloxypropyl)-1,1,3,3-tetramethyldisiloxane will be described. Figure 15 It is a figure showing the structural formula of the epoxy compound added in the first modification. Figure 16 It is a figure showing the evaluation result of the moisture resistance in the first modification. Figure 17 It is a figure showing the structural formula of the epoxy compound added in the second modification. Figure 18 It is a figure showing the evaluation result of the moisture resistance in the second modification. Figure 19 It is a figure showing the structural formula of the epoxy compound added in the third modification. Figure 20 It is a figure showing the evaluation result of the moisture resistance in the third modification. Figure 21 It is a figure showing the structural formula of the epoxy compound added in the fourth modification. Figure 22 It is a figure showing the evaluation result of the moisture resistance in the fourth modification.

[0097] The moisture resistance tests of the first to fourth modifications and Figures 4 to 7The evaluation methods of the examples and comparative examples shown were similarly used to measure the change in resistance value at 85°C and 85% RH and make comparisons. "Initial" represents the resistance value in the initial state before being put into 85°C and 85% RH, "after 100 h" represents the resistance value after 100 hours at 85°C and 85% RH, "after 240 h" represents the resistance value after 240 hours at 85°C and 85% RH, "after 500 h" represents the resistance value after 500 hours at 85°C and 85% RH, and "after 1000 h" represents the resistance value after 1000 hours at 85°C and 85% RH. The resistance values in the initial states of the first to fourth modified examples were approximately 0 Ω. Therefore, the resistance values after 100, 240, 500, and 1000 hours respectively correspond to the change amounts of the resistance values from the initial state. The larger the change amount of the resistance value, the lower the moisture resistance.

[0098] The first to fourth modified examples have the same structure as this embodiment except for the different types of epoxy compounds contained in the conductive adhesive. The epoxy compound contained in the conductive adhesive of the first modified example is Figure 15 1,4 - butanediol diglycidyl ether shown. The epoxy compound contained in the conductive adhesive of the second modified example is Figure 17 neopentyl glycol diglycidyl ether shown. The epoxy compound contained in the conductive adhesive of the third modified example is Figure 19 trimethylolpropane triglycidyl ether shown. The epoxy compound contained in the conductive adhesive of the fourth modified example is Figure 21 polyethylene glycol diglycidyl ether shown. The content rate of the epoxy compound in each of the first to fourth modified examples is 1.0% by weight.

[0099] In Figure 16 the case of the first modified example shown, the resistance value hardly rises until 100 hours have passed, starts to rise at 240 hours, and rises to about 14 Ω at most at 1000 hours. In Figure 18 the case of the second modified example shown, the resistance value hardly rises until 240 hours have passed, starts to rise at 500 hours, and rises to about 5 - 6 Ω at most at 1000 hours. In Figure 20 the case of the third modified example shown, the resistance value hardly rises until 240 hours have passed, starts to rise at 500 hours, and rises to about 5 - 6 Ω at most at 1000 hours. In Figure 22 the case of the fourth modified example shown, the resistance value hardly rises even after 1000 hours.

[0100] In Figure 9 the case of the comparative example shown, the resistance value starts to rise at 100 hours and exceeds 15 Ω at most at 1000 hours. InFigure 12 In the case of the illustrated embodiment, the resistance value is also approximately 0 Ω after 1000 hours. Therefore, the rise start of the resistance value in the first to fourth modified examples is slower than that in the comparative example. In addition, the maximum value of the resistance value in the first modified example is larger than the maximum value of the resistance value in the embodiment and smaller than the maximum value of the resistance value in the comparative example. The maximum values of the resistance values in the second and third modified examples are larger than the maximum value of the resistance value in the embodiment and are less than half of the maximum value of the resistance value in the comparative example. The maximum value of the resistance value in the fourth modified example is of the same degree as the maximum value of the resistance value in the embodiment. In other words, the moisture resistance of the first to fourth modified examples is improved as compared with the comparative example, similarly to the embodiment. In addition, the moisture resistance of the first modified example is higher than the moisture resistance of the comparative example. The moisture resistance of the second modified example is substantially the same as the moisture resistance of the third modified example and is higher than the moisture resistance of the first modified example. The moisture resistance of the fourth modified example is substantially the same as the moisture resistance of the embodiment and is higher than the moisture resistance of the second and third modified examples.

[0101] In summary, it can be seen that the epoxy compound for improving the moisture resistance of the cured product of the silicone-based conductive adhesive is not limited to 1,3-bis(3-glycidyloxypropyl)-1,1,3,3-tetramethyldisiloxane, and any epoxy compound having two or more epoxy groups is acceptable. In addition, since the moisture resistance in the embodiment and the fourth modified example is particularly high, it is speculated that the characteristics of the epoxy compound for improving the moisture resistance may include a silicone compound having a siloxane bond, a main chain length connecting two epoxy groups (for example, 9 atoms or more), etc.

[0102] As described above, in the crystal oscillator 1 of the present embodiment, the conductive holding members 36a and 36b connecting the connection electrodes 16a and 16b to the electrode pads 33a and 33b are cured products of a conductive adhesive mainly composed of a silicone resin, and the conductive adhesive contains an epoxy compound having two or more epoxy groups.

[0103] Thereby, it is possible to improve the frequency-temperature characteristics of the crystal vibration element while suppressing the resistance value variation between the base member and the crystal vibration element in a high-humidity environment. Specifically, it is possible to suppress the increase in the contact resistance between the conductive holding member and the connection electrode and the contact resistance between the conductive holding member and the electrode pad.

[0104] In addition, in the crystal oscillator 1 of the present embodiment, the outermost surface of the electrode pads 33a and 33b contains gold.

[0105] If the conductive adhesive contains an epoxy compound having two or more epoxy groups, even if gold with low adhesion to the resin-based adhesive is included on the outermost surface of the electrode pad, it is possible to suppress an increase in the contact resistance between the conductive adhesive and the electrode pad in a high-humidity environment. Therefore, surface treatment of the electrode pad (e.g., Ag sputtering) for improving adhesion to the conductive adhesive is not required, and a decrease in the corrosion resistance of the electrode pad caused by such surface treatment does not occur. Therefore, a crystal oscillator with high corrosion resistance and high moisture resistance can be provided.

[0106] In addition, in the crystal oscillator 1 of the present embodiment, gold is contained on the outermost surface of the connection electrodes 16a and 16b.

[0107] If the conductive adhesive contains an epoxy compound having two or more epoxy groups, even if gold with low adhesion to the resin-based adhesive is included on the outermost surface of the connection electrode, it is possible to suppress an increase in the contact resistance between the conductive adhesive and the connection electrode in a high-humidity environment. Therefore, surface treatment of the connection electrode (e.g., Ag sputtering) for improving adhesion to the conductive adhesive is not required, and a decrease in the corrosion resistance of the connection electrode caused by such surface treatment does not occur. Therefore, a crystal oscillator with high corrosion resistance and high moisture resistance can be provided.

[0108] In addition, in the crystal oscillator 1 of the present embodiment, a joining member 50 that joins the base member 30 and the lid member 40 to seal the internal space 49 is further provided, and the joining member 50 is a cured product of a resin-based adhesive.

[0109] When the base member and the lid member are joined using a resin-based adhesive, the manufacturing cost of the crystal oscillator can be reduced compared to metal joining, but the moisture permeability increases. Even in such a case, it is possible to suppress a change in the resistance value between the base member and the crystal vibration element in a high-humidity environment. Therefore, a crystal oscillator with high moisture resistance while suppressing the manufacturing cost can be provided.

[0110] In addition, in the crystal oscillator 1 of the present embodiment, the epoxy compound contained in the conductive adhesive is an organosilicon compound having a siloxane bond, namely 1,3-bis(3-glycidyloxypropyl)-1,1,3,3-tetramethyldisiloxane.

[0111] In addition, in the crystal oscillator 1 of the present embodiment, the content rate of the epoxy compound in the conductive adhesive is 0.5% by weight to 10.0% by weight.

[0112] Thereby, it is possible to suppress a deterioration in the frequency-temperature dependence of the crystal oscillator 1 and at the same time suppress an increase in the resistance value of the conductive holding members 36a and 36b in a high-humidity environment.

[0113] It should be noted that the embodiments of the present invention are not limited to crystal resonators, and can also be applied to piezoelectric resonators. An example of a piezoelectric resonator (Piezoelectric Resonator Unit) is a quartz crystal resonator (Quartz Crystal Resonator Unit) having a quartz crystal vibration element (Quartz Crystal Resonator). The quartz crystal vibration element uses a quartz crystal wafer (Quartz Crystal Element) as a piezoelectric wafer excited by the piezoelectric effect, but the piezoelectric wafer can be formed of any piezoelectric material such as a piezoelectric single crystal, a piezoelectric ceramic, a piezoelectric thin film, or a piezoelectric polymer film. As an example, the piezoelectric single crystal can be lithium niobate (LiNbO3). Similarly, the piezoelectric ceramic can be barium titanate (BaTiO3), lead titanate (PbTiO3), lead zirconate titanate (Pb(Zr x Ti 1－x )O3; PZT), aluminum nitride (AlN), lithium niobate (LiNbO3), lithium metaniobate (LiNb2O6), bismuth titanate (Bi4Ti3O 12 ), lithium tantalate (LiTaO3), lithium tetraborate (Li2B4O7), lanthanum gallium silicate (La3Ga5SiO 14 ) or tantalum pentoxide (Ta2O5), etc. The piezoelectric thin film can be a piezoelectric thin film formed by sputtering the above piezoelectric ceramic on a substrate such as quartz or sapphire. The piezoelectric polymer film can be polylactic acid (PLA), polyvinylidene fluoride (PVDF), or a vinylidene fluoride / trifluoroethylene (VDF / TrFE) copolymer, etc. The above various piezoelectric materials can be used by laminating them with each other, or can be laminated on other components.

[0114] The embodiments of the present invention are not limited to piezoelectric resonators, and include: a first adherend having conductivity, a second adherend having conductivity, and a conductive adhesive portion connecting the first adherend and the second adherend. The conductive adhesive portion is a cured product of a conductive adhesive mainly composed of a silicone resin. As long as it is an electronic component containing an epoxy compound having two or more epoxy groups in the conductive adhesive, it can be applied. If the crystal resonator 1 is cited, the first adherend corresponds to the connection electrodes 16a and 16b, the second adherend corresponds to the electrode pads 33a and 33b, the conductive adhesive portion corresponds to the conductive holding members 36a and 36b, and the electronic component corresponds to the crystal resonator 1. That is, as long as it is an electronic component having a connection portion bonded by a conductive adhesive portion inside and requiring conduction with the conductive adhesive portion, there is no particular limitation, and it can be an embodiment of the present invention. Such electronic components are, for example, resonators other than crystal resonators, transistors, diodes, capacitors, inductors, resistors, integrated circuits (ICs), imaging elements, display elements, sensors, MEMS elements, etc.

[0115] For example, if the electronic component is a vibration element having a mechanical vibration part, a load generated by the vibration is applied to the conductive adhesive part. Therefore, when the adhesion force between the adhered part and the conductive adhesive part is insufficient, at the interface between the adhered part and the conductive adhesive part, the contact resistance increases due to the decrease in the adhesion force. In the worst case, the conductivity is lost due to peeling. Thus, even for an electronic component configured to apply a load to the interface between the adhered part and the conductive adhesive part due to impact during transportation, displacement during operation, etc., according to the embodiment of the present invention, an increase in the contact resistance in a high-humidity environment can be suppressed.

[0116] Hereinafter, the configuration of the electronic device according to other embodiments of the present invention will be described. It should be noted that in the following embodiments, descriptions of matters common to the above-described first embodiment are omitted, and only differences will be described. In particular, the same functions and effects based on the same structure will not be described in sequence.

[0117] <Second Embodiment>

[0118] Refer to Figure 8 The structure of the electronic device 100 according to the second embodiment will be described. Figure 8 It is a cross-sectional view schematically showing the structure of the electronic device according to the second embodiment.

[0119] The electronic device 100 according to the second embodiment includes: an electronic component 70, a substrate 90 having a metal layer 91, and a conductive adhesive part 80 that connects the electronic component 70 and the metal layer 91 of the substrate 90. The conductive adhesive part 80 is a cured product of a conductive adhesive mainly composed of a silicone resin, and an epoxy compound having two or more epoxy groups is contained in the conductive adhesive. Figure 8 For example, a crystal oscillator is depicted as the electronic component 70. However, the electronic component 70 is not limited to a crystal oscillator, and may also be an oscillator other than a crystal oscillator, a transistor, a diode, a capacitor, an inductor, a resistor, an integrated circuit (IC), an imaging element, a display element, a sensor, a MEMS element, etc.

[0120] A cured product of a conductive adhesive mainly composed of a silicone resin, and a conductive adhesive part containing an epoxy compound having two or more epoxy groups can be used for external electrical connection of an electronic component as in the second embodiment, or can be used for internal electrical connection of an electronic component as in the first embodiment.

[0121] Hereinafter, a part or all of the embodiments of the present invention will be appended, and their effects will be described. It should be noted that the present invention is not limited to the following appendices.

[0122] According to one aspect of the present invention, a crystal oscillator can be provided, comprising: a crystal vibration element having an exciting electrode and a connection electrode electrically connected to the exciting electrode; a base member having an electrode pad; a conductivity maintaining member connecting the electrode and the electrode pad; and a lid member forming an internal space for accommodating the crystal vibration element between the base member; the conductivity maintaining member is a cured product of a conductive adhesive mainly composed of a silicone resin, and the conductive adhesive contains an epoxy compound having two or more epoxy groups.

[0123] Thereby, improvement in the frequency-temperature characteristics of the crystal vibration element can be achieved, and the resistance value variation between the base member and the crystal vibration element in a high-humidity environment can be suppressed. Specifically, an increase in the contact resistance between the conductivity maintaining member and the connection electrode, and an increase in the contact resistance between the conductivity maintaining member and the electrode pad can be suppressed. That is, a crystal oscillator with high moisture resistance can be provided.

[0124] As one aspect, the epoxy group is a part of a glycidyl group.

[0125] If the epoxy group of the epoxy compound contained in the conductive adhesive is a part of a glycidyl group, a crystal oscillator with particularly high moisture resistance can be provided.

[0126] As one aspect, the outermost surface of the electrode pad contains gold.

[0127] If the conductive adhesive contains an epoxy compound having two or more epoxy groups, even if the outermost surface of the electrode pad contains gold with low adhesion to the resin-based adhesive, an increase in the contact resistance between the conductive adhesive and the electrode pad in a high-humidity environment can be suppressed. Therefore, a surface treatment (e.g., Ag sputtering) of the electrode pad for improving the adhesion to the conductive adhesive is not required, and a reduction in the corrosion resistance of the electrode pad caused by the surface treatment does not occur. Therefore, a crystal oscillator with high corrosion resistance and high moisture resistance can be provided.

[0128] As one aspect, the outermost surface of the connection electrode contains gold.

[0129] If the conductive adhesive contains an epoxy compound having two or more epoxy groups, even if the outermost surface of the connection electrode contains gold with low adhesion to the resin-based adhesive, an increase in the contact resistance between the conductive adhesive and the connection electrode in a high-humidity environment can be suppressed. Therefore, a surface treatment (e.g., Ag sputtering) of the connection electrode for improving the adhesion to the conductive adhesive is not required, and a reduction in the corrosion resistance of the connection electrode caused by the surface treatment does not occur. Therefore, a crystal oscillator with high corrosion resistance and high moisture resistance can be provided.

[0130] As one aspect, a joining member for joining the base member and the lid member to seal the internal space is further provided, and the joining member is a resin-based adhesive.

[0131] When the joining of the base member and the lid member is performed by bonding with a resin-based adhesive, the manufacturing cost of the crystal oscillator can be reduced compared to metal joining, but the moisture permeability increases. Even in such a case, it is possible to suppress the change in the resistance value between the base member and the crystal vibrating element in a high-humidity environment. Therefore, it is possible to provide a crystal oscillator that suppresses the manufacturing cost and has high moisture resistance.

[0132] As one aspect, the epoxy compound is a silicone compound.

[0133] As one aspect, the epoxy compound has a siloxane bond.

[0134] As one aspect, the epoxy compound has 1,3-bis(3-glycidyloxypropyl)-1,1,3,3-tetramethyldisiloxane or has 1,3-bis(3-glycidyloxypropyl)-1,1,3,3-tetramethyldisiloxane as a constituent unit.

[0135] In addition, in the crystal oscillator 1 of the present embodiment, the content of the epoxy compound in the conductive adhesive is 0.5% by weight to 10.0% by weight.

[0136] Thereby, it is possible to suppress the deterioration of the frequency-temperature dependence of the crystal oscillator and at the same time suppress the increase in the resistance value of the conductive holding member in a high-humidity environment.

[0137] According to another aspect of the present invention, there can be provided an electronic device including an electronic component, a substrate having a metal layer, and a conductive bonding portion that connects the electronic component to the metal layer of the substrate; the conductive bonding portion is a cured product of a conductive adhesive mainly composed of a silicone resin, and the conductive adhesive contains an epoxy compound having two or more epoxy groups.

[0138] Thereby, it is possible to suppress the change in the resistance value between the electronic component and the substrate in a high-humidity environment. That is, it is possible to provide an electronic device having high moisture resistance.

[0139] According to still another aspect of the present invention, there can be provided an electronic component including: a first adherend having conductivity, a second adherend having conductivity, and a conductive bonding portion that connects the first adherend and the second adherend; the conductive bonding portion is a cured product of a conductive adhesive mainly composed of a silicone resin, and the conductive adhesive contains an epoxy compound having two or more epoxy groups.

[0140] Thereby, it is possible to suppress the change in the resistance value between the first adherend and the second adherend in a high-humidity environment. That is, it is possible to provide an electronic device having high moisture resistance.

[0141] As a method, the first adherend is a connection electrode provided on a vibration element having a mechanical vibration section.

[0142] Even for an electronic component configured to apply a load to the interface between the adherend and the conductive adhesive section due to impacts during transportation, displacements during operation, etc., like an electronic component, according to the embodiments of the present invention, an increase in contact resistance in a high-humidity environment can be suppressed.

[0143] As described above, according to one aspect of the present invention, a crystal oscillator, an electronic component, and an electronic device with improved reliability can be provided.

[0144] It should be noted that the embodiments described above are for facilitating the understanding of the present invention and are not used to limitatively interpret the present invention. The present invention can be changed / improved without departing from its gist, and its equivalents are also included in the present invention. That is, a technical solution obtained by appropriately designing and changing each embodiment by those skilled in the art is included in the scope of the present invention as long as it has the features of the present invention. For example, each element, its configuration, material, conditions, shape, size, etc. possessed by each embodiment are not limited to the examples and can be appropriately changed. For example, the vibration element and oscillator of the present invention can be used in a timepiece or a load sensor. In addition, as long as it is technically possible, each element possessed by each embodiment can be combined, and a technical solution obtained by combining them is included in the scope of the present invention as long as it includes the features of the present invention.

[0145] Symbol Explanation

[0146] 1... Crystal oscillator,

[0147] 10... Crystal vibration element,

[0148] 11... Crystal piece,

[0149] 14a, 14b... Excitation electrodes,

[0150] 15a, 15b... Lead-out electrodes,

[0151] 16a, 16b... Connection electrodes,

[0152] 30... Base member,

[0153] 31... Substrate,

[0154] 33a, 33b... Electrode pads,

[0155] 34a, 34b... Through electrodes,

[0156] 35a to 35d... External electrodes,

[0157] 36a, 36b... Conductive holding members,

[0158] 40... cover member

[0159] 50... joining member

Claims

1. A crystal oscillator, comprising: A crystal vibration element having an exciting electrode and a connection electrode electrically connected to the exciting electrode, A base member having an electrode pad, A conductive holding member connecting the connection electrode and the electrode pad, and A cover member forming an internal space for accommodating the crystal vibration element between the cover member and the base member; The conductive holding member is a cured product of a conductive adhesive mainly composed of a silicone resin, The conductive adhesive contains an epoxy compound having two or more epoxy groups, The epoxy compound is a silicone compound.

2. The crystal oscillator according to claim 1, wherein, The epoxy group is a part of a glycidyl group.

3. The crystal oscillator according to claim 1 or 2, wherein, The outermost surface of the electrode pad contains gold.

4. The crystal oscillator according to claim 1 or 2, wherein, The outermost surface of the connection electrode contains gold.

5. The crystal oscillator according to claim 1 or 2, wherein, Further provided is a joining member that joins the base member and the cover member to seal the internal space, The joining member is a cured product of a resin-based adhesive.

6. The crystal oscillator according to claim 1 or 2, wherein, The epoxy compound has a siloxane bond.

7. The crystal oscillator according to claim 1 or 2, wherein, The epoxy compound has 1,3-bis(3-glycidyloxypropyl)-1,1,3,3-tetramethyldisiloxane or has the 1,3-bis(3-glycidyloxypropyl)-1,1,3,3-tetramethyldisiloxane as a structural unit.

8. The crystal oscillator according to claim 1 or 2, wherein The content rate of the epoxy compound in the conductive adhesive is 0.5 wt% to 10.0 wt%.

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