Oscillator

Abstract

To provide an oscillator having an excellent frequency temperature characteristic.SOLUTION: The oscillator includes a package including an accommodation space, a resonator element disposed in the accommodation space and bonded to the package via a first bonding member, a circuit element disposed in the accommodation space, flip-chip mounted on the package via a second bonding member, and including an oscillation circuit that oscillates the resonator element, and a third bonding member that bonds the resonator element and the circuit element. The vibration element includes a plate-shaped vibration substrate having a first surface located on the circuit element side and a second surface in a front-back relationship with the first surface, a first excitation electrode disposed on the first surface, and a second excitation electrode disposed on the second surface. The vibration substrate includes a vibration portion on which the first and second excitation electrodes are disposed and which is bonded to the package via a first bonding member, a bonding portion bonded to the circuit element via a third bonding member, and a stress relaxation portion located between the vibration portion and the bonding portion.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to an oscillator. [Background technology]

[0002] The crystal oscillator described in Patent Document 1 has a package including a base with a recessed portion opening on its top surface and a lid bonded to the top surface of the base to seal the opening of the recessed portion. The recessed portion has a first recessed portion opening on the top surface of the base and a second recessed portion opening on the bottom surface of the first recessed portion. The crystal oscillator further includes a piezoelectric diaphragm bonded to the bottom surface of the first recessed portion and an integrated circuit element bonded to the bottom surface of the second recessed portion. The integrated circuit element is bonded to the bottom surface of the second recessed portion using face-down bonding technology, with its wiring surface facing the bottom surface of the second recessed portion. The piezoelectric diaphragm is bonded at its base end to the bottom surface of the first recessed portion via a conductive resin adhesive and at its tip end to the back surface of the integrated circuit element via a silicone-based resin adhesive. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-142946 Summary of the Invention [Problem to be solved by the invention]

[0004] By bonding the tip of the piezoelectric diaphragm to the integrated circuit element in this way, the gap dimension between the piezoelectric diaphragm and the integrated circuit element can be reliably maintained as the designed gap dimension. However, on the other hand, this can affect the vibration mode, making it more likely that a local drop in the frequency-temperature characteristic, known as a "temperature characteristic dip," will occur, which may lead to deterioration of the frequency-temperature characteristic. [Means for solving the problem]

[0005] The oscillator of the present invention comprises: a package having an accommodating space; a vibration element disposed in the accommodation space and joined to the package via a first joining member; a circuit element that is disposed in the accommodating space, is flip-chip mounted to the package via a second bonding member, and includes an oscillation circuit that oscillates the vibration element to generate an oscillation signal; a third bonding member bonding the vibration element and the circuit element together, the circuit element is located between the vibration element and the second bonding member, the vibration element includes a plate-shaped vibration substrate having a first surface located on the circuit element side and a second surface opposite to the first surface, a first excitation electrode disposed on the first surface, and a second excitation electrode disposed on the second surface and facing the first excitation electrode via the vibration substrate; The vibration substrate has a vibration section on which the first excitation electrode and the second excitation electrode are arranged and which is joined to the package via the first joining member, a joining section which is joined to the circuit element via the third joining member, and a stress relief section which is located between the vibration section and the joining section. [Brief explanation of the drawings]

[0006] [Figure 1] 1 is a cross-sectional view showing an oscillator according to a first embodiment. [Figure 2] FIG. 2 is a top view showing the top surface of the vibration element. [Figure 3] FIG. 2 is a perspective view showing the bottom surface of the vibration element. [Figure 4] FIG. 2 is a top view showing the bonding state of the vibration element. [Figure 5] FIG. 10 is a top view showing deformation of the vibration element. [Figure 6] FIG. 10 is a top view of a vibration element included in an oscillator according to a second embodiment. [Figure 7] FIG. 10 is a top view of a vibration element included in an oscillator according to a third embodiment. [Figure 8] FIG. 10 is a top view of a vibration element included in an oscillator according to a fourth embodiment. [Figure 9] FIG. 10 is a top view of a vibration element included in an oscillator according to a fifth embodiment. [Figure 10] 10 is a cross-sectional view taken along line AA in FIG. 9. [Figure 11] FIG. 10 is a cross-sectional view of an oscillator according to a sixth embodiment. [Figure 12] FIG. 13 is a perspective view showing the bottom surface of a vibration element included in an oscillator according to a seventh embodiment. [Figure 13] FIG. 2 is a top view showing the bonding state of the vibration element. [Figure 14] 13 is a top view showing a bonding state of vibration elements included in an oscillator according to an eighth embodiment. FIG. [Figure 15] 15 is a cross-sectional view taken along line BB in FIG. 14. DETAILED DESCRIPTION OF THE INVENTION

[0007] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the oscillator of the present invention will now be described in detail with reference to the accompanying drawings.

[0008] First Embodiment Fig. 1 is a cross-sectional view showing an oscillator according to a first embodiment. Fig. 2 is a top view showing the top surface of a vibration element. Fig. 3 is a perspective view showing the bottom surface of the vibration element. Fig. 4 is a top view showing the bonding state of the vibration element. Fig. 5 is a top view showing deformation of the vibration element.

[0009] For ease of explanation, each of Figures 1 to 5 illustrates an X-axis, a Y-axis, and a Z-axis that are orthogonal to one another. For ease of explanation, the direction along the X-axis will also be referred to as the X-axis direction, which is the first direction, the direction along the Y-axis will also be referred to as the Y-axis direction, which is the second direction, and the direction along the Z-axis will also be referred to as the Z-axis direction. The arrowed side of each axis will also be referred to as the "plus side," and the opposite side as the "negative side." The arrowed side of the Z-axis direction, which is the thickness direction of oscillator 1, will also be referred to as the "upper side," and the opposite side as the "lower side."

[0010] The oscillator 1 shown in FIG. 1 is a TCXO (temperature compensated crystal oscillator), and has a package 2 having an accommodation space S, and a resonator element 5 and a circuit element 6 accommodated in the accommodation space S of the package 2.

[0011] The package 2 has a base substrate 3. The base substrate 3 is made of ceramics such as alumina. The base substrate 3 has an upper surface and a lower surface, which are opposite sides of the base substrate 3. The base substrate 3 also has a recess 31 with a bottom that opens on the upper surface. The recess 31 is made up of multiple recesses, and has a first recess 311 that opens on the upper surface, and a second recess 312 that opens on the bottom of the first recess 311 and has a smaller opening than the first recess 311.

[0012] Furthermore, a pair of internal terminals 321 are arranged on the bottom surface of the first recess 311, a plurality of internal terminals 322 are arranged on the bottom surface of the second recess 312, and a plurality of external terminals 323 are arranged on the lower surface of the base substrate 3. Each of the internal terminals 321 and each of the external terminals 323 is electrically connected to the corresponding internal terminal 322 via internal wiring (not shown) formed in the base substrate 3.

[0013] The vibration element 5 is bonded to the bottom surface of the first recess 311 via a first bonding member B1 and is electrically connected to each of the internal terminals 321, while the circuit element 6 is bonded to the bottom surface of the second recess 312 via a second bonding member B2 and is electrically connected to each of the internal terminals 322. The vibration element 5 is located above the circuit element 6, i.e., on the positive side in the Z-axis direction. In other words, the circuit element 6 is disposed between the second bonding member B2 and the vibration element 5. In addition, in a plan view from the Z-axis direction, the tip end (the end on the positive side in the X-axis direction) of the vibration element 5 overlaps with the circuit element 6, and the base end (the end on the negative side in the X-axis direction) located opposite the tip end overlaps with the bottom surface of the first recess 311 without overlapping with the circuit element 6.

[0014] The package 2 also has a lid 4. The lid 4 is made of a metal material such as Kovar. The lid 4 is bonded to the upper surface of the base substrate 3 via a bonding member and closes the opening of the recess 31. By closing the opening of the recess 31 with the lid 4 in this way, an airtight storage space S is formed inside the package 2. The resonator element 5 and the circuit element 6 are then housed in the storage space S. The storage space S is in a reduced pressure state, preferably a state closer to a vacuum. This reduces the CI (crystal impedance) value of the resonator element 5 and improves the oscillation characteristics. However, the atmosphere of the storage space S is not particularly limited.

[0015] 1, the circuit element 6 has a semiconductor substrate 60 having a wiring surface 6a as its lower surface and a back surface 6b as its upper surface opposite to the wiring surface 6a. A plurality of various circuit elements (not shown) for configuring the necessary circuits are formed on the wiring surface 6a. A wiring layer 600 is formed on the wiring surface 6a to electrically connect the circuit elements to each other so that predetermined functions are performed. Furthermore, a plurality of connection terminals 69 are arranged on the wiring layer 600 to electrically connect the circuit element 6 to the internal terminals 322.

[0016] The circuit element 6 configured as above is flip-chip mounted on the bottom surface of the second recess 312. Specifically, the circuit element 6 is bonded to the bottom surface of the second recess 312 via a plurality of conductive second bonding members B2, with the wiring surface 6a facing downward, i.e., toward the bottom surface of the second recess 312. Furthermore, each connection terminal 69 is electrically connected to a corresponding internal terminal 322 via the second bonding members B2. The second bonding members B2 are various metal balls such as gold balls and copper balls. However, the configuration of the second bonding members B2 is not particularly limited as long as it is capable of flip-chip mounting.

[0017] The circuit element 6 also has a temperature sensing element 61, an oscillation circuit 62, and a temperature compensation circuit 63 arranged on the wiring surface 6a side. The temperature sensing element 61 is arranged on the wiring surface 6a, and the oscillation circuit 62 and the temperature compensation circuit 63 are formed by electrically connecting the circuit elements formed on the wiring surface 6a via a wiring layer 600.

[0018] The temperature-sensing element 61 is, for example, a resistor (thin-film thermistor) whose resistance value changes according to temperature, and can detect temperature from the magnitude of the resistance value. The oscillation circuit 62 is electrically connected to the vibration element 5, amplifies the output signal of the vibration element 5, and feeds back the amplified signal to the vibration element 5, causing the vibration element 5 to oscillate and generate an oscillation signal. The temperature compensation circuit 63 compensates for the frequency-temperature characteristics of the oscillation signal generated by the oscillation circuit 62 based on the temperature detected by the temperature-sensing element 61. In other words, temperature compensation is performed so that the frequency fluctuation of the oscillation signal is smaller than the frequency-temperature characteristics of the vibration element 5 itself. With this configuration, frequency fluctuation of the oscillation signal due to temperature changes is suppressed, resulting in oscillator 1 with excellent oscillation characteristics.

[0019] The oscillator circuit 62 may be, for example, a Pierce oscillator circuit, an inverter oscillator circuit, a Colpitts oscillator circuit, a Hartley oscillator circuit, etc. The temperature compensation circuit 63 may be, for example, a circuit that adjusts the oscillation frequency of the oscillator circuit 62 by adjusting the capacitance of a variable capacitance circuit connected to the oscillator circuit 62, or a circuit that adjusts the frequency of the oscillation signal generated by the oscillator circuit 62 using a PLL circuit or a direct digital synthesizer circuit.

[0020] The vibration element 5 is an AT-cut quartz crystal vibration element. AT-cut quartz crystal vibration elements have third-order frequency-temperature characteristics, resulting in excellent frequency stability. As shown in FIGS. 2 and 3, the vibration element 5 is cut out of quartz crystal by AT-cutting, and includes a plate-shaped vibration substrate 51 having a bottom surface 51a as a first surface and a top surface 51b as a second surface, which are opposite sides of the vibration substrate 51, and electrodes arranged on the surface of the vibration substrate 51.

[0021] The vibration substrate 51 is disposed parallel to the XY plane. When viewed from the vibration element 5 in a plan view, that is, when viewed from the Z-axis direction, the vibration substrate 51 has a rectangular shape with its longitudinal direction in the X-axis direction. Therefore, hereinafter, the end (one end) of the vibration substrate 51 on the negative side in the X-axis direction will also be referred to as the base end, and the end (the other end) on the positive side in the X-axis direction will also be referred to as the tip end. The vibration substrate 51 has a vibration section 511, a joint 512 located on the tip side of the vibration section 511, a connection section 513 located between the vibration section 511 and the joint 512 and connecting them, and a stress relaxation section 514 arranged alongside the connection section 513 in the Y-axis direction and configured to absorb and relax stress applied to the vibration section 511.

[0022] The stress relief portion 514 also has a pair of slits 514a and 514b formed with the connecting portion 513 sandwiched therebetween. This configuration facilitates the formation of the stress relief portion 514. One slit 514a is located on the positive side of the connecting portion 513 in the Y-axis direction, and the other slit 514b is located on the negative side of the connecting portion 513 in the Y-axis direction. The slit 514a is a through-hole that penetrates through the lower surface 51a and the upper surface 51b, extends straight along the Y-axis direction, and its end on the positive side in the Y-axis direction opens to a side surface of the vibrating substrate 51 on the positive side in the Y-axis direction. Similarly, the slit 514b is a through-hole that penetrates through the lower surface 51a and the upper surface 51b, extends straight along the Y-axis direction, and its end on the negative side in the Y-axis direction opens to a side surface of the vibrating substrate 51 on the negative side in the Y-axis direction. The slits 514a and 514b are formed symmetrically with respect to the connecting portion 513.

[0023] The electrodes include a first excitation electrode 521 arranged on the lower surface 51a of the vibrating part 511, and a second excitation electrode 531 arranged on the upper surface 51b of the vibrating part 511 and facing the first excitation electrode 521 across the vibrating part 511. The portion of the vibrating part 511 sandwiched between the first and second excitation electrodes 521 and 531 becomes a vibration region Q.

[0024] The electrode also has a first connection terminal 522 and a second connection terminal 532 arranged side by side in the Y-axis direction at the base end of the lower surface 51a of the vibrating part 511. The electrode also has a first escape wiring 523 that electrically connects the first excitation electrode 521 and the first connection terminal 522, and a second escape wiring 533 that electrically connects the second excitation electrode 531 and the second connection terminal 532.

[0025] However, the configuration of the vibration element 5 is not particularly limited. For example, the planar shape of the vibration substrate 51 is not limited to a rectangular (rectangular) shape, and may be a circular shape. Furthermore, as the vibration element 5, in addition to an AT-cut quartz crystal vibration element, an SC-cut quartz crystal vibration element, a BT-cut quartz crystal vibration element, or a tuning-fork type quartz crystal vibration element may also be used. Furthermore, a surface acoustic wave resonator, other piezoelectric vibration elements, piezoelectric vibration elements made of piezoelectric materials other than a quartz crystal vibration element, a MEMS (Micro Electro Mechanical Systems) resonator element, or the like may also be used.

[0026] 4, the vibrating element 5 has a base end joined to the bottom surface of the first recess 311 via two conductive first bonding members B1. The first connecting terminal 522 is electrically connected to one of the internal terminals 321 via one first bonding member B1, and the second connecting terminal 532 is electrically connected to the other internal terminal 321 via one first bonding member B1. This electrically connects the vibrating element 5 and the circuit element 6 via the base substrate 3.

[0027] The first bonding member B1 is a conductive resin adhesive. In particular, in this embodiment, an epoxy-based conductive adhesive in which a metal filler such as Ag (silver) filler is dispersed in an epoxy-based resin is used. This results in the first bonding member B1 having sufficiently high thermal conductivity. Furthermore, compared to, for example, a case in which a metal bump or the like is used, the first bonding member B1 is softer, and can effectively absorb and alleviate stress generated between the vibration element 5 and the base substrate 3. Furthermore, by using a conductive resin adhesive for the first bonding member B1, the diameter of the first bonding member B1 is larger than, for example, a case in which the first bonding member B1 is a metal bump. For example, the diameter of the first bonding member B1 when a conductive resin adhesive is used is approximately 200 μm, and the diameter of the first bonding member B1 when a metal bump is used is approximately 50 μm. Therefore, by using a conductive resin adhesive for the first bonding member B1, heat from the base substrate 3 is more easily transferred to the vibration element 5 via the first bonding member B1. However, the configuration of the first joint member B1 is not particularly limited.

[0028] As shown in FIGS. 1 and 4 , the oscillator 1 further includes a conductive third bonding member B3 located between the vibration element 5 and the circuit element 6. The third bonding member B3 bonds a bonding portion 512 located at the tip of the vibration element 5 to the back surface 6b, which is the upper surface of the circuit element 6. With this configuration, the vibration element 5 is supported by the first and third bonding members B1 and B3, allowing the gap dimension between the vibration element 5 and the circuit element 6 to be accurately adjusted to the design value. Furthermore, the posture of the vibration element 5 is stabilized, effectively suppressing fluctuations in the oscillation characteristics of the vibration element 5. This stabilizes the oscillation characteristics of the oscillator 1. In particular, in this embodiment, the base end of the vibration element 5 is bonded to the package 2 via the first bonding member B1, and the tip end opposite the base end is bonded to the circuit element 6 via the third bonding member B3. Therefore, the vibration element 5 is supported at both ends, making the above-described effects more pronounced.

[0029] Furthermore, by joining the vibration element 5 and the circuit element 6 with the third bonding member B3, the vibration element 5 and the circuit element 6 are thermally connected via the third bonding member B3. This reduces the temperature difference between the vibration element 5 and the circuit element 6, particularly the temperature difference between the vibration element 5 and the temperature sensing element 61. As a result, the error between the actual temperature of the vibration element 5 and the compensation temperature (the temperature detected by the temperature sensing element 61) used in the temperature compensation circuit 63 is reduced, thereby improving the temperature compensation accuracy. This results in a highly accurate oscillator 1.

[0030] In particular, the third bonding member B3 of this embodiment is conductive. Therefore, it has sufficiently high thermal conductivity. This reduces the temperature difference between the vibration element 5 and the temperature-sensing element 61, improving temperature compensation accuracy. The third bonding member B3 of this embodiment is a conductive resin-based adhesive. Similar to the first bonding member B1, the third bonding member B3 is an epoxy-based conductive adhesive in which a metal filler, such as Ag (silver) filler, is dispersed in an epoxy-based resin. By using a conductive resin-based adhesive as the third bonding member B3, the same effects as the first bonding member B1 can be achieved. That is, the third bonding member B3 becomes soft, effectively absorbing and alleviating stress generated between the vibration element 5 and the circuit element 6. Furthermore, the diameter of the third bonding member B3 is easily increased, which allows for more efficient heat transfer between the vibration element 5 and the circuit element 6. This reduces the temperature difference between the vibration element 5 and the temperature-sensing element 61, improving temperature compensation accuracy. However, the configuration of the third bonding member B3 is not particularly limited, and it may be made of, for example, an insulating material.

[0031] Here, by joining the base end of the vibration element 5 to the bottom surface of the first recess 311 with the first bonding member B1 and joining the tip end to the circuit element 6 with the third bonding member B3, the above-mentioned effects can be obtained, but stress can be easily applied to the vibration element 5. Therefore, for example, deformation of the vibration part 511 can affect the vibration mode, making it more likely that a so-called "temperature characteristic dip" will occur, in which the frequency-temperature characteristic drops locally, and this temperature characteristic dip may lead to deterioration of the frequency-temperature characteristic.

[0032] Therefore, the vibration element 5 of this embodiment has a stress relaxation portion 514 formed between the vibration portion 511 and the joint portion 512 to absorb and relax the stress applied to the vibration portion 511. By providing the stress relaxation portion 514, i.e., the pair of slits 514a, 514b, the rigidity of the connection portion 513 is reduced, making it more likely to deform. Therefore, for example, as shown by arrows P1 and P2 in FIG. 5 , one of the vibration portion 511 and the joint portion 512 is more likely to displace relative to the other, and the stress applied to the vibration portion 511 due to this displacement can be effectively absorbed and relaxed. Therefore, a temperature characteristic dip is less likely to occur, and deterioration of the frequency-temperature characteristic due to the temperature characteristic dip can be effectively suppressed.

[0033] In particular, by configuring the stress relaxation portion 514 with a pair of slits 514a, 514b as in this embodiment, one of the vibrating portion 511 and the joint portion 512 can be smoothly displaced in any direction relative to the other. This makes it more difficult for a temperature characteristic dip to occur, and makes it possible to more effectively suppress deterioration of the frequency-temperature characteristic due to the temperature characteristic dip. However, the configuration of the stress relaxation portion 514 is not particularly limited.

[0034] The oscillator 1 has been described above. As described above, the oscillator 1 includes the package 2 having the accommodation space S, the vibration element 5 disposed in the accommodation space S and bonded to the package 2 via the first bonding member B1, the circuit element 6 disposed in the accommodation space S and flip-chip mounted to the package 2 via the second bonding member B2, and including an oscillation circuit 62 that oscillates the vibration element 5 to generate an oscillation signal, and the third bonding member B3 bonding the vibration element 5 and the circuit element 6. The circuit element 6 is located between the vibration element 5 and the second bonding member B2. The vibration element 5 also includes a plate-shaped vibration substrate 51 having a lower surface 51a, which is a first surface located on the circuit element 6 side, and an upper surface 51b, which is a second surface opposite the lower surface 51a, a first excitation electrode 521 disposed on the lower surface 51a, and a second excitation electrode 531, which is disposed on the upper surface 51b and faces the first excitation electrode 521 via the vibration substrate 51. The vibration substrate 51 also includes a vibration section 511, on which a first excitation electrode 521 and a second excitation electrode 531 are arranged, and which is bonded to the package 2 via a first bonding member B1; a bonding section 512, which is bonded to the circuit element 6 via a third bonding member B3; and a stress relief section 514 located between the vibration section 511 and the bonding section 512. This configuration provides a first effect: since the vibration element 5 is supported by the first and third bonding members B1 and B3, the gap dimension between the vibration element 5 and the circuit element 6 can be accurately adjusted to the design value. Furthermore, the posture of the vibration element 5 is stabilized, and fluctuations in the oscillation characteristics of the vibration element 5 can be effectively suppressed. This stabilizes the oscillation characteristics of the oscillator 1. Furthermore, a second effect: since the vibration element 5 includes the stress relief section 514, stress applied to the vibration section 511 can be effectively absorbed and relieved. This reduces the likelihood of a temperature dip, effectively suppressing deterioration of the frequency-temperature characteristics due to the temperature dip. In this way, the oscillator 1 can achieve both the first and second effects.

[0035] As described above, the vibration element 5 is joined to the package 2 at one end, i.e., the base end, via the first bonding member B1, and is joined to the circuit element 6 at the other end, i.e., the tip end, located opposite the base end, via the third bonding member B3. With this configuration, the vibration element 5 is supported at both ends, making the above-mentioned effects more pronounced.

[0036] Furthermore, as described above, when the direction in which the vibrating portion 511 and the bonding portion 512 are aligned in a plan view of the vibrating element 5, i.e., when viewed from the Z-axis direction, is defined as the X-axis direction, which is a first direction, and the direction perpendicular to the X-axis direction is defined as the Y-axis direction, which is a second direction, the stress relaxation portion 514 has a pair of slits 514a, 514b arranged opposite each other on both sides in the Y-axis direction and extending along the Y-axis direction. This configuration makes it easy to form the stress relaxation portion 514. Furthermore, one of the vibrating portion 511 and the bonding portion 512 can be smoothly displaced in any direction relative to the other. This makes it less likely that a temperature dip will occur, and makes it possible to more effectively suppress deterioration of the frequency-temperature characteristics due to a temperature dip.

[0037] Second Embodiment FIG. 6 is a top view of a vibration element included in an oscillator according to the second embodiment.

[0038] The oscillator 1 according to this embodiment is similar to the oscillator 1 according to the first embodiment described above, except that the configuration of the vibration element 5, specifically the configuration of the stress relaxation portion 514, is different. Therefore, in the following description, differences between the oscillator 1 according to this embodiment and the first embodiment described above will be mainly described, and descriptions of similar points will be omitted. Furthermore, in the drawings of this embodiment, the same reference numerals are used to designate similar components to those in the above-described embodiment.

[0039] As shown in FIG. 6, in the vibration element 5 of this embodiment, the stress relaxation portion 514 is configured with one slit 514a arranged on one side in the Y-axis direction. Such a configuration makes it easy to form the stress relaxation portion 514. The slit 514a is located on the positive side in the Y-axis direction of the connection portion 513. The slit 514a is a through-hole that penetrates the lower surface 51a and the upper surface 51b, extends straight along the Y-axis direction, and further, its end on the positive side in the Y-axis direction opens to the side surface of the vibration substrate 51 on the positive side in the Y-axis direction. However, the configuration of the stress relaxation portion 514 is not particularly limited, and for example, contrary to this embodiment, it may be configured with only the slit 514b.

[0040] As described above, in the oscillator 1 of this embodiment, when the direction in which the vibrating portion 511 and the bonding portion 512 are aligned in a plan view of the vibrating element 5, that is, when viewed from the Z-axis direction, is defined as the X-axis direction, which is a first direction, and the direction perpendicular to the X-axis direction is defined as the Y-axis direction, which is a second direction, the stress relaxation portion 514 is disposed on one side in the Y-axis direction and has the slit 514a extending along the Y-axis direction. With this configuration, the stress relaxation portion 514 can be easily formed.

[0041] The second embodiment can also achieve the same effects as the first embodiment described above.

[0042] Third Embodiment FIG. 7 is a top view of a vibration element included in an oscillator according to a third embodiment.

[0043] The oscillator 1 according to this embodiment is similar to the oscillator 1 according to the first embodiment described above, except that the configuration of the vibration element 5, specifically the configuration of the stress relaxation portion 514, is different. Therefore, in the following description, differences between the oscillator 1 according to this embodiment and the first embodiment described above will be mainly described, and descriptions of similar points will be omitted. Furthermore, in the drawings of this embodiment, the same reference numerals are used to designate similar components to those in the above-described embodiment.

[0044] 7, the vibration element 5 of this embodiment has a pair of connecting portions 513 arranged on both sides of the stress absorbing portion 514 in the Y-axis direction. The stress absorbing portion 514 is composed of one slit 514c. The slit 514c is a through-hole that penetrates the lower surface 51a and the upper surface 51b, extends straight along the Y-axis direction, and is closed at both ends by the connecting portions 513.

[0045] The third embodiment can also achieve the same effects as the first embodiment described above.

[0046] <Fourth embodiment> FIG. 8 is a top view of a vibration element included in an oscillator according to a fourth embodiment.

[0047] The oscillator 1 according to this embodiment is similar to the oscillator 1 according to the first embodiment described above, except that the configuration of the vibration element 5, specifically the configuration of the stress relaxation portion 514, is different. Therefore, in the following description, differences between the oscillator 1 according to this embodiment and the first embodiment described above will be mainly described, and descriptions of similar points will be omitted. Furthermore, in the drawings of this embodiment, the same reference numerals are used to designate similar components to those in the above-described embodiment.

[0048] As shown in Figure 8, in the vibration element 5 of this embodiment, the stress relaxation portion 514 is composed of a U-shaped slit 515 that surrounds the vibration portion 511 on three sides, and further, the joint portion 512 is U-shaped and surrounds the stress relaxation portion 514 on three sides (the positive side in the X-axis direction and both sides in the Y-axis direction).

[0049] Slit 515 is a through hole that penetrates lower surface 51a and upper surface 51b, and has a first portion 515a that is located on the tip side (positive side in the X-axis direction) of vibrating part 511 and extends along the Y-axis direction, a second portion 515b that is located on the positive side of vibrating part 511 in the Y-axis direction and extends along the X-axis direction, and a third portion 515c that is located on the negative side of vibrating part 511 in the Y-axis direction and extends along the X-axis direction.

[0050] The joint 512 includes a first portion 512a located on the tip side (positive side in the X-axis direction) of the first portion 515a and extending along the Y-axis direction; a second portion 512b located on the positive side of the second portion 515b and extending along the X-axis direction; and a third portion 512c located on the negative side of the third portion 515c and extending along the X-axis direction. Both ends of the joint 512, i.e., the negative ends of the second and third portions 512b and 512c in the X-axis direction, are connected to the vibrating portion 511 via connecting portions 513. The first portion 512a of the joint 512 is joined to the circuit element 6 via a third joining member B3. With this configuration, the stress absorbing portion 514 surrounds the vibrating portion 511 on three sides, making it easier for the vibrating portion 511 and the joint 512 to be displaced relative to each other. Furthermore, it is possible to ensure a long stress transmission distance from the joint portion of the joint portion 512 with the third joint member B3 to each connection portion 513. Therefore, the stress applied to the vibrating portion 511 can be effectively absorbed and alleviated.

[0051] As described above, in the oscillator 1 of the present embodiment, when the direction in which the vibrating portion 511 and the joint portion 512 are aligned in a plan view of the vibrating element 5, that is, when viewed from the Z-axis direction, is defined as the X-axis direction, which is a first direction, and the direction perpendicular to the X-axis direction is defined as the Y-axis direction, which is a second direction, the stress relief portion 514 has a first portion 515a located between the vibrating portion 511 and the joint portion 512 and extending along the Y-axis direction, a second portion 515b located on one side of the vibrating portion 511 in the Y-axis direction and extending along the X-axis direction, and a third portion 515c located on the other side of the vibrating portion 511 in the Y-axis direction and extending along the X-axis direction, and surrounds three sides of the vibrating portion 511. With this configuration, the stress relief portion 514 surrounds the vibrating portion 511 on three sides, which makes it easy for the vibrating portion 511 and the joint portion 512 to be displaced relative to each other. Furthermore, it is possible to ensure a long stress transmission distance from the joint portion of the joint portion 512 with the third joint member B3 to each connection portion 513. Therefore, the stress applied to the vibrating portion 511 can be effectively absorbed and alleviated.

[0052] The fourth embodiment can also achieve the same effects as the first embodiment described above.

[0053] Fifth Embodiment Fig. 9 is a top view of a vibration element included in an oscillator according to a fifth embodiment, and Fig. 10 is a cross-sectional view taken along line AA in Fig. 9.

[0054] The oscillator 1 according to this embodiment is similar to the oscillator 1 according to the first embodiment described above, except that the configuration of the vibration element 5, specifically the configuration of the stress relaxation portion 514, is different. Therefore, in the following description, differences between the oscillator 1 according to this embodiment and the first embodiment will be mainly described, and descriptions of similar points will be omitted. Furthermore, in each drawing of this embodiment, the same reference numerals are used to designate similar components to those in the above-described embodiment.

[0055] 9 and 10, in the vibration element 5 of this embodiment, the stress relaxation portion 514 has a recess 514d formed on the upper surface 51b of the vibration substrate 51. The recess 514d extends straight along the Y-axis direction, and both ends thereof open to the side surfaces located on both sides of the vibration substrate 51 in the Y-axis direction. In this configuration, the thickness of the connection portion 513 is thinner than the thicknesses of the vibration portion 511 and the bonding portion 512 located on both sides thereof. This makes it easier for the connection portion 513 to deform, and allows the stress applied to the vibration portion 511 to be effectively absorbed and relaxed.

[0056] The fifth embodiment can also achieve the same effects as the first embodiment described above.

[0057] Sixth Embodiment FIG. 11 is a cross-sectional view of an oscillator according to a sixth embodiment.

[0058] The oscillator 1 according to this embodiment is similar to the oscillator 1 according to the first embodiment described above, except for the configuration of the circuit element 6. Therefore, in the following description, differences between the oscillator 1 according to this embodiment and the first embodiment described above will be mainly described, and descriptions of similar points will be omitted. Furthermore, in the drawings of this embodiment, the same reference numerals are used to designate the same components as those in the above-described embodiment.

[0059] 11, the circuit element 6 of this embodiment has an insulating film 68 arranged on the rear surface 6b and a first electrode pad 67 arranged on the insulating film 68. By arranging the first electrode pad 67 on the insulating film 68 in this manner, it is possible to easily insulate the first electrode pad 67 from the rear surface 6b, which is the ground surface. The insulating film 68 is not particularly limited, but can be, for example, a silicon oxide film formed by thermal oxidation, sputtering, or the like.

[0060] Furthermore, the first electrode pad 67 overlaps the bonding portion 512 located at the tip of the vibration element 5 in a plan view from the Z-axis direction. The first electrode pad 67 also overlaps the temperature-sensitive element 61 in a plan view from the Z-axis direction. The circuit element 6 also has a first via 66 formed on the semiconductor substrate 60, which penetrates the wiring surface 6a and the back surface 6b and thermally connects the first electrode pad 67 and the temperature-sensitive element 61. Although not shown, an insulating film is formed between the first via 66 and the semiconductor substrate 60, insulating them from each other.

[0061] The first electrode pads 67 and the first vias 66 are made of a material having a thermal conductivity higher than at least the constituent material of the semiconductor substrate 60. In this embodiment, the first electrode pads 67 and the first vias 66 are made of a conductive material, specifically, various metal materials such as gold (Au), copper (Cu), and aluminum (Al). This results in the first electrode pads 67 and the first vias 66 having high thermal conductivity. However, the constituent materials of the first electrode pads 67 and the first vias 66 are not particularly limited. Furthermore, since the first electrode pads 67 and the first vias 66 are not used for electrical connection, they may be made of an insulating material.

[0062] In this circuit element 6, the third bonding member B3 is bonded to the first electrode pad 67. This thermally connects the vibration element 5 and the temperature sensitive element 61 via the third bonding member B3, the first electrode pad 67, and the first via 66. This reduces the temperature difference between the vibration element 5 and the temperature sensitive element 61, allowing temperature compensation by the temperature compensation circuit 63 to be performed more accurately. In particular, in this embodiment, the tip of the vibration element 5, the first electrode pad 67, the first via 66, and the temperature sensitive element 61 overlap one another in a plan view from the Z-axis direction. This effectively minimizes the thermal path between the vibration element 5 and the temperature sensitive element 61, further reducing the temperature difference between the vibration element 5 and the temperature sensitive element 61.

[0063] As described above, in the oscillator 1 of this embodiment, the circuit element 6 includes a semiconductor substrate 60 having a wiring surface 6a located on the second bonding member B2 side and a back surface 6b opposite the wiring surface 6a and located on the vibration element 5 side; a first electrode pad 67 located on the back surface 6b side of the semiconductor substrate 60 and bonded to the bonding portion 512 via the third bonding member B3; a first via 66 formed in the semiconductor substrate 60 and penetrating the wiring surface 6a and the back surface 6b; an oscillation circuit 62 located on the wiring surface 6a side of the semiconductor substrate 60; a temperature sensing element 61; and a temperature compensation circuit 63 that compensates for the frequency-temperature characteristics of the oscillation signal based on the temperature detected by the temperature sensing element 61. The temperature sensing element 61 and the first electrode pad 67 are connected via the first via 66. This configuration reduces the temperature difference between the vibration element 5 and the temperature sensing element 61, allowing for more accurate temperature compensation by the temperature compensation circuit 63.

[0064] The sixth embodiment can also achieve the same effects as the first embodiment described above.

[0065] Seventh Embodiment Fig. 12 is a perspective view showing the bottom surface of the vibration element of the oscillator according to the seventh embodiment, and Fig. 13 is a top view showing the bonding state of the vibration element.

[0066] The oscillator 1 according to this embodiment is similar to the oscillator 1 according to the first embodiment described above, except for the configuration of the vibration element 5. Therefore, in the following description, differences between the oscillator 1 according to this embodiment and the first embodiment described above will be mainly described, and descriptions of similar points will be omitted. Furthermore, in each drawing of this embodiment, the same reference numerals are used to designate the same components as those in the above-described embodiment.

[0067] 12, the vibration element 5 of this embodiment has a conductor pattern 55 that is not in contact with the electrodes. The conductor pattern 55 is arranged on the vibration part 511 and has a first part 55a that surrounds three sides (the positive side in the X-axis direction and both sides in the Y-axis direction) of the first excitation electrode 521, a second part 55b that is arranged on the joint part 512, and a third part 55c that is arranged on the connection part 513 and connects the first part 55a and the second part 55b.

[0068] As shown in FIG. 13 , the vibration element 5 is bonded to the bottom surface of the first recess 311 in the vibration section 511 via four first bonding members B1. The first connection terminal 522 is electrically connected to one of the internal terminals 321 via one first bonding member B1, and the second connection terminal 532 is electrically connected to the other internal terminal 321 via one first bonding member B1. This electrically connects the vibration element 5 and the circuit element 6 via the base substrate 3. Furthermore, the remaining two first bonding members B1 connect both ends of the conductor pattern 55 to the bottom surface of the first recess 311. This thermally connects the conductor pattern 55 and the base substrate 3 via the two first bonding members B1, allowing heat from the base substrate 3 to be efficiently transferred to the vibration element 5.

[0069] 13, the vibration element 5 is joined to the upper surface of the circuit element 6 at the joint 512 via the third joint member B3. The conductive pattern 55 is connected to the upper surface of the circuit element 6 by the third joint member B3. This thermally connects the conductive pattern 55 and the circuit element 6 via the third joint member B3, and the heat of the vibration element 5 is efficiently transferred to the circuit element 6.

[0070] As described above, in the oscillator 1, the conductor pattern 55 is bonded to the first bonding member B1 and the third bonding member B3. Therefore, heat from the base substrate 3 is efficiently transferred to the vibration element 5 via the first bonding member B1, and further, the heat is efficiently transferred to the circuit element 6 via the third bonding member B3. This reduces the temperature difference between the vibration element 5 and the circuit element 6, particularly the temperature difference between the vibration element 5 and the temperature sensing element 61. As a result, the error between the actual temperature of the vibration element 5 and the compensation temperature (the temperature detected by the temperature sensing element 61) used in the temperature compensation circuit 63 is reduced, thereby improving the temperature compensation accuracy. This results in a highly accurate oscillator 1.

[0071] As described above, in the oscillator 1 of this embodiment, the vibration element 5 has the conductor pattern 55 located around the first excitation electrode 521, and the conductor pattern 55 is joined to the first joining member B1 and the third joining member B3. With this configuration, the temperature difference between the vibration element 5 and the temperature sensing element 61 is reduced, improving the temperature compensation accuracy. This results in a highly accurate oscillator 1.

[0072] The seventh embodiment can also achieve the same effects as the first embodiment described above.

[0073] Eighth Embodiment Fig. 14 is a top view showing a bonding state of the vibration element included in the oscillator according to the eighth embodiment, and Fig. 15 is a cross-sectional view taken along line BB in Fig. 14 .

[0074] The oscillator 1 according to this embodiment is similar to the oscillator 1 according to the first embodiment described above, except that the orientation of the vibration element 5 is different. Therefore, in the following description, differences between the oscillator 1 according to this embodiment and the first embodiment described above will be mainly described, and descriptions of similar points will be omitted. Furthermore, in each drawing of this embodiment, the same reference numerals are used to designate the same components as those in the above-described embodiment.

[0075] As shown in FIG. 14 , in the oscillator 1 of this embodiment, the vibration element 5 is rotated 180° around the Z axis relative to the first embodiment described above, i.e., the tip end faces the negative side in the X-axis direction and the base end faces the positive side in the X-axis direction. In a plan view from the Z-axis direction, the base end of the vibration element 5 overlaps with the circuit element 6, and the tip end overlaps with the bottom surface of the first recess 311. The tip end of the vibration element 5 is bonded to the bottom surface of the first recess 311 via a first bonding member B1. In this embodiment, the internal terminal 321 is omitted from the bottom surface of the first recess 311, and the vibration element 5 and the base substrate 3 are not electrically connected. However, this is not limited thereto. For example, in order to increase the bonding strength between the first bonding member B1 and the base substrate 3, a dummy terminal to which the first bonding member B1 is bonded may be disposed on the bottom surface of the first recess 311.

[0076] 15, the circuit element 6 has a pair of second electrode pads 65 arranged on an insulating film 68. In plan view from the Z-axis direction, the pair of second electrode pads 65 overlap with the base ends of the vibration element 5 and are arranged side by side in the Y-axis direction. The circuit element 6 also has a pair of second vias 64 that penetrate the wiring surface 6a and the back surface 6b and electrically connect each second electrode pad 65 to the oscillation circuit 62. Although not shown, an insulating film is formed between the second vias 64 and the semiconductor substrate 60 to insulate them. The second electrode pads 65 and the second vias 64, like the first electrode pads 67 and the first vias 66, are made of various metal materials such as gold (Au), copper (Cu), and aluminum (Al).

[0077] 15, the vibrating element 5 is bonded at its base end to the upper surface of the circuit element 6 via two conductive third bonding members B3. The first connection terminal 522 is electrically connected to one of the second electrode pads 65 via one of the third bonding members B3, and the second connection terminal 532 is electrically connected to the other of the second electrode pads 65 via the other of the third bonding members B3. This electrically connects the vibrating element 5 and the oscillator circuit 62 via the third bonding member B3. This configuration shortens the electrical path between the vibrating element 5 and the oscillator circuit 62 compared to, for example, the first embodiment, in which the vibrating element 5 and the oscillator circuit 62 are electrically connected via the base substrate 3, thereby reducing parasitic capacitance. This results in an oscillator 1 suitable for generating higher frequencies of oscillation signals.

[0078] As described above, in the oscillator 1 of this embodiment, the circuit element 6 includes a semiconductor substrate 60 having a wiring surface 6a located on the second bonding member B2 side and a back surface 6b opposite the wiring surface 6a and located on the vibration element 5 side; a pair of second electrode pads 65 disposed on the back surface 6b of the semiconductor substrate 60 and electrically connected to the first excitation electrode 521 and the second excitation electrode 531 via the third bonding member B3; and second vias 64 formed on the semiconductor substrate 60, penetrating the wiring surface 6a and the back surface 6b, electrically connecting the oscillation circuit 62 disposed on the wiring surface 6a side to each of the second electrode pads 65. With this configuration, the electrical path between the vibration element 5 and the oscillation circuit 62 can be shortened, and parasitic capacitance can be reduced accordingly, compared to, for example, the configuration in which the vibration element 5 and the oscillation circuit 62 are electrically connected via the base substrate 3, as in the first embodiment described above. This configuration therefore provides an oscillator 1 suitable for increasing the frequency of oscillation signals.

[0079] The eighth embodiment can also achieve the same effects as the first embodiment.

[0080] Although the oscillator of the present invention has been described above based on the illustrated embodiment, the present invention is not limited to this, and the configuration of each part can be replaced with any configuration having a similar function. Also, other arbitrary components may be added to the present invention. Furthermore, the above-described embodiments may be combined as appropriate. [Explanation of symbols]

[0081] 1...oscillator, 2...package, 3...base substrate, 31...recess, 311...first recess, 312...second recess, 321...internal terminal, 322...internal terminal, 323...external terminal, 4...lid, 5...vibration element, 51...vibration substrate, 51a...bottom surface, 51b...top surface, 511...vibration portion, 512...joint portion, 512a...first portion, 512b...second portion, 512c...third portion, 513...connection portion, 514...stress relaxation portion, 514a...slit, 514b...slit, 514c...slit, 514d...recess, 515...slit, 515a...first portion, 515b...second portion, 515c...third portion, 521...first excitation electrode, 5 22...first connection terminal, 523...first lead-out wiring, 531...second excitation electrode, 532...second connection terminal, 533...second lead-out wiring, 55...conductor pattern, 55a...first portion, 55b...second portion, 55c...third portion, 6...circuit element, 6a...wiring surface, 6b...rear surface, 60...semiconductor substrate, 61...thermosensitive element, 62...oscillation circuit, 63...temperature compensation circuit, 64...second via, 65...second electrode pad, 66...first via, 67...first electrode pad, 68...insulating film, 69...connection terminal, 600...wiring layer, B1...first bonding member, B2...second bonding member, B3...third bonding member, P1...arrow, P2...arrow, Q...vibration area, S...accommodation space

Claims

1. a package having a storage space; a vibration element disposed in the accommodation space and joined to the package via a first joining member; a circuit element that is disposed in the accommodation space, is flip-chip mounted to the package via a second bonding member, and includes an oscillation circuit that oscillates the vibration element to generate an oscillation signal; a third bonding member bonding the vibration element and the circuit element together, the circuit element is located between the vibration element and the second bonding member, the vibration element includes a plate-shaped vibration substrate having a first surface located on the circuit element side and a second surface opposite to the first surface, a first excitation electrode disposed on the first surface, and a second excitation electrode disposed on the second surface and facing the first excitation electrode via the vibration substrate; The oscillator is characterized in that the vibration substrate has a vibration section on which the first excitation electrode and the second excitation electrode are arranged and which is joined to the package via the first joining member, a joining section which is joined to the circuit element via the third joining member, and a stress relief section located between the vibration section and the joining section.

2. 2. The oscillator according to claim 1, wherein the vibration element is joined to the package at one end via the first joining member, and is joined to the circuit element at the other end opposite the one end via the third joining member.

3. In a plan view of the vibration element, when a direction in which the vibration portion and the joint portion are aligned is defined as a first direction and a direction perpendicular to the first direction is defined as a second direction, The oscillator according to claim 1 , wherein the stress relaxation portion has a pair of slits arranged on opposite sides in the second direction and extending along the second direction.

4. In a plan view of the vibration element, when a direction in which the vibration portion and the joint portion are aligned is defined as a first direction and a direction perpendicular to the first direction is defined as a second direction, The oscillator according to claim 1 , wherein the stress relaxation portion is arranged on one side in the second direction and has a slit extending along the second direction.

5. In a plan view of the vibration element, when a direction in which the vibration portion and the joint portion are aligned is defined as a first direction and a direction perpendicular to the first direction is defined as a second direction, 2. The oscillator of claim 1, wherein the stress relaxation portion has a first portion located between the vibrating portion and the joint portion and extending along the second direction, a second portion located on one side of the vibrating portion in the second direction and extending along the first direction, and a third portion located on the other side of the vibrating portion in the second direction and extending along the first direction, and surrounds the vibrating portion on three sides.

6. the circuit element includes a semiconductor substrate having a wiring surface located on the second bonding member side and a back surface opposite to the wiring surface and located on the vibration element side; a first electrode pad disposed on the rear surface side of the semiconductor substrate and bonded to the bonding portion via the third bonding member; a first via formed in the semiconductor substrate and penetrating the wiring surface and the back surface; the oscillation circuit disposed on the wiring surface side of the semiconductor substrate, a temperature sensing element, and a temperature compensation circuit that compensates for the frequency temperature characteristics of the oscillation signal based on the temperature detected by the temperature sensing element, The oscillator according to claim 1 , wherein the temperature sensitive element and the first electrode pad are connected through the first via.

7. the circuit element includes a semiconductor substrate having a wiring surface located on the second bonding member side and a back surface opposite to the wiring surface and located on the vibration element side; a pair of second electrode pads disposed on the rear surface side of the semiconductor substrate and electrically connected to the first excitation electrode and the second excitation electrode via the third bonding member; 2. The oscillator according to claim 1, further comprising a second via formed on the semiconductor substrate, penetrating the wiring surface and the back surface, and electrically connecting the oscillation circuit arranged on the wiring surface side to each of the second electrode pads.

8. the vibration element has a conductor pattern located around the first excitation electrode, The oscillator according to claim 1 , wherein the conductor pattern is joined to the first joining member and the third joining member.

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