Oscillator

Abstract

To provide an oscillator capable of securing stable frequency characteristics of a piezoelectric vibrating element and having high operation reliability while achieving miniaturization and thinning.SOLUTION: An oscillator 1 includes: a package 2 including a mounting substrate 20 having a first mounting surface 20a and a second mounting surface 20b facing each other in a thickness direction T; a piezoelectric vibrating element 3 mounted on the first mounting surface; and an integrated circuit 4 having a plurality of integrated circuit terminals and mounted on the second mounting surface. On the first mounting surface, a mounting electrode 40 is formed that conducts electricity to an excitation electrode of a piezoelectric vibrating element. On the second mounting surface, a plurality of integrated circuit electrodes 81 are formed that conducts electricity to the integrated circuit terminal. In an overlap region W where the integrated circuit electrode and the mounting electrode overlap each other in a plan view from the thickness direction, a capacitance suppression section 70 is provided to suppress stray capacitance generated between the integrated circuit electrode and the mounting electrode in the overlap region.SELECTED DRAWING: Figure 4

Description

[Technical Field]

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

[0002] 2. Description of the Related Art Conventionally, oscillators equipped with piezoelectric vibrating reeds using quartz crystal have been used in electronic devices such as mobile phones. As an example of this type of oscillator, Patent Document 1 discloses an oscillator that includes a tuning-fork-shaped piezoelectric vibrating piece, a circuit chip (circuit element) having an oscillation circuit, and a container (package) that houses the piezoelectric vibrating piece and the circuit chip.

[0003] The container includes a substrate having a first surface on which the circuit chip is mounted and a second surface on which the piezoelectric vibrating reed is mounted, such that the piezoelectric vibrating reed and the circuit chip are disposed in the thickness direction of the oscillator with the substrate sandwiched therebetween. A pair of monitor electrodes and a plurality of chip electrodes are formed on the first surface of the substrate. The monitor electrodes are electrodes that are electrically connected to the excitation electrodes of the piezoelectric vibrating reed and are used, for example, to measure the frequency of the piezoelectric vibrating reed during the manufacturing process. The chip electrodes include, for example, signal output electrodes, ground connection electrodes, power supply electrodes, and control electrodes. The circuit chip is mounted on the first surface of the substrate in a state where it is electrically connected to the chip electrodes via bonding members such as gold bumps.

[0004] A pair of mount electrodes electrically connected to the monitor electrodes are formed on the second surface of the substrate, and the piezoelectric vibrating reed is mounted on the second surface of the substrate in a state where it is electrically connected to the pair of mount electrodes via a bonding member such as gold bumps. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2023-80598 Summary of the Invention [Problem to be solved by the invention]

[0006] To accommodate the trend toward smaller and thinner electronic devices incorporating such oscillators, further miniaturization and thinning of the oscillators themselves is required. To meet such demands, for example, in conventional oscillators, the spacing between the multiple electrodes (a pair of monitor electrodes and multiple chip electrodes) formed on the first surface of the substrate becomes narrow. This makes it easy for stray capacitance (parasitic capacitance) to occur between the electrodes. Therefore, in the conventional oscillator described above, the difference in stray capacitance is suppressed by adjusting the distance between the electrodes on the first surface of the substrate.

[0007] However, in the conventional oscillator described above, the electrodes formed on the first surface of the substrate and the mount electrodes formed on the second surface of the substrate are arranged so as to overlap in the thickness direction of the oscillator with the substrate sandwiched between them, which leaves a concern that stray capacitance may occur in the thickness direction of the substrate between the mount electrodes and the chip electrodes (signal output electrodes, ground connection electrodes, power supply electrodes, control electrodes, etc.). In particular, as oscillators become smaller and thinner, the mount electrode and the chip electrodes tend to overlap in the thickness direction of the oscillator, and the distance between the mount electrode and the multiple chip electrodes also becomes closer, which makes it easier for large stray capacitance to occur.

[0008] When we look at the relationship between piezoelectric vibrating reeds and stray capacitance, the frequency voltage characteristics of piezoelectric vibrating reeds tend to deteriorate due to the influence of the generated stray capacitance. Therefore, the generation of large stray capacitance makes it difficult to obtain stable frequency characteristics of the piezoelectric vibrating reed, which leads to a decrease in the operational reliability of the oscillator.

[0009] The present invention has been made in consideration of these circumstances, and its purpose is to provide an oscillator that is compact and thin, yet can ensure stable frequency characteristics of the piezoelectric vibrating reed, and has high operational reliability. [Means for solving the problem]

[0010] (1) The oscillator of the present invention comprises a package including a mounting substrate having a first mounting surface and a second mounting surface facing each other in the thickness direction, a piezoelectric vibrating piece mounted on the first mounting surface, and an integrated circuit having a plurality of integrated circuit terminals and mounted on the second mounting surface, wherein the first mounting surface is formed with a mounting electrode that is conductive to an excitation electrode of the piezoelectric vibrating piece, and the second mounting surface is formed with a plurality of integrated circuit electrodes that are conductive to the integrated circuit terminals, and wherein, in a plan view seen from the thickness direction, an overlapping region where the integrated circuit electrode and the mounting electrode overlap each other is provided with a capacitance suppression portion that suppresses stray capacitance that occurs between the integrated circuit electrode and the mounting electrode in the overlapping region.

[0011] According to the oscillator of the present invention, a piezoelectric vibrating reed and an integrated circuit are arranged with a mounting substrate that constitutes a package sandwiched therebetween. The piezoelectric vibrating reed is mounted via mounting electrodes formed on a first mounting surface of the mounting substrate, and is fixed in a state in which the excitation electrodes are electrically connected to the mounting electrodes. The integrated circuit is mounted via multiple integrated circuit electrodes formed on a second mounting surface of the mounting substrate, and is fixed in a state in which multiple integrated circuit terminals are electrically connected to the multiple integrated circuit electrodes, respectively. Supplying a current to the excitation electrodes causes the piezoelectric vibrating reed to vibrate in a predetermined resonant frequency band, and the current can be converted into an electrical signal using its piezoelectric properties. The integrated circuit can then be used to generate an output signal, such as a clock signal, based on the electrical signal. This allows the oscillator to function.

[0012] In particular, with respect to the relationship between the mounting electrodes formed on the first mounting surface and the integrated circuit electrodes formed on the second mounting surface, a capacitance suppressing portion is provided in an overlapping region where the integrated circuit electrodes and the mounting electrodes overlap each other in the thickness direction of the mounting substrate. Therefore, even if the mounting electrodes and the integrated circuit electrodes are arranged close to each other in the thickness direction, it is possible to suppress stray capacitance occurring between the mounting electrodes and the integrated circuit electrodes in the overlapping region. Therefore, even if the oscillator itself is made smaller and thinner, it is possible to suppress the deterioration of voltage characteristics due to the influence of stray capacitance, and the piezoelectric vibrating reed can be vibrated with stable frequency characteristics. Therefore, it is possible to generate an output signal stably, and it is possible to obtain an oscillator with high operational reliability.

[0013] (2) The capacitance suppression portion may include a non-electrode portion formed on the integrated circuit electrode so as to reduce the area of ​​the overlapping portion of the integrated circuit electrode that overlaps with the mounting electrode in a planar view from the thickness direction.

[0014] In this case, by forming a non-electrode portion by removing a portion of the integrated circuit electrode, for example, by forming a notch-shaped portion by recessing the outer shape of the integrated circuit electrode inward, or by forming an opening-shaped portion that is surrounded by the integrated circuit electrode, the area of ​​the overlapping portion that overlaps with the mounted electrode in a plan view from the thickness direction can be reduced. In particular, since this is a simple method of simply forming a non-electrode portion on the integrated circuit electrode itself, it is possible to form the non-electrode portion simultaneously when forming the integrated circuit electrode on the second mounting surface of the mounting board, for example.

[0015] (3) The capacitance suppression portion may include a non-electrode portion formed on the mounting electrode so as to reduce the area of ​​the overlapping portion of the mounting electrode that overlaps with the integrated circuit electrode in a planar view from the thickness direction.

[0016] In this case, by forming a non-electrode portion by removing a portion of the mount electrode, for example, by forming a notch-like portion by recessing the outer shape of the mount electrode inward, or by forming an opening-like portion surrounded by the mount electrode, the area of ​​the overlapping portion with the integrated circuit electrode in a plan view from the thickness direction can be reduced. In particular, since this is a simple method of simply forming a non-electrode portion on the mount electrode itself, it is possible to form the non-electrode portion simultaneously when forming the mount electrode.

[0017] (4) The electrode-free portion may be formed so as to eliminate the overlapping portion.

[0018] In this case, since the mounting electrodes and the integrated circuit electrodes do not overlap in a plan view seen from the thickness direction, the occurrence of stray capacitance between the mounting electrodes and the integrated circuit electrodes can be suppressed, which allows the piezoelectric vibrating reed to vibrate with more stable frequency characteristics and further improves the operational reliability of the oscillator.

[0019] (5) The capacitance suppressing portion may include an insulating film formed on the second mounting surface so as to be located between the second mounting surface and the integrated circuit electrode.

[0020] In this case, the insulating film can suppress the occurrence of stray capacitance between the mounting electrode and the integrated circuit electrode in the overlapping region. Therefore, the piezoelectric vibrating reed can vibrate with more stable frequency characteristics, further improving the operational reliability of the oscillator. In particular, since the method only requires the formation of an insulating film and does not require changing the shape of the integrated circuit electrode itself, it leads to efficient manufacturing.

[0021] (6) A monitor electrode that is electrically connected to the mounting electrode may be formed on the second mounting surface, and the monitor electrode may be formed to have an area equal to or smaller than that of the integrated circuit electrode.

[0022] In this case, since the oscillator is provided with a monitor electrode, the monitor electrode can be used to supply current to the excitation electrode via the mounting electrode during the oscillator assembly process, allowing the vibration status of the piezoelectric vibrating reed to be confirmed. As a result, the vibration of the piezoelectric vibrating reed can be adjusted so that it vibrates within a predetermined frequency band, further improving operational reliability. In particular, since the area of ​​the monitor electrode is the same as or smaller than that of the integrated circuit electrode, the integrated circuit electrode can be made larger accordingly. Therefore, even if an electrode-free portion is formed on the integrated circuit electrode, the integrated circuit electrode can have a sufficient area and can properly function as an electrode.

[0023] (7) The piezoelectric vibrating piece may include a piezoelectric plate having a pair of vibrating arms arranged parallel to each other and a base that integrally fixes the base ends of the vibrating arms, and an excitation electrode formed on the outer surface of the piezoelectric plate that vibrates the pair of vibrating arms when a voltage is applied.

[0024] In this case, by supplying a current to the excitation electrodes, the pair of vibrating arms can be vibrated in a predetermined frequency band in a direction toward or away from each other. In particular, a general tuning fork-type vibrating arm having a pair of vibrating arms can be used as the piezoelectric vibrating reed, thereby reducing component costs. [Effects of the Invention]

[0025] According to the present invention, it is possible to ensure stable frequency characteristics of the piezoelectric vibrating reed while achieving miniaturization and thinning, and to provide an oscillator with high operational reliability. [Brief explanation of the drawings]

[0026] [Figure 1] 1 is a perspective view showing an external appearance of an oscillator according to an embodiment of the present invention; [Figure 2] 2 is a top view of the oscillator shown in FIG. 1, with the lid and seal ring shown in FIG. 1 removed. FIG. [Figure 3] FIG. 2 is an exploded perspective view of the oscillator shown in FIG. [Figure 4] 3 is a longitudinal cross-sectional view of the oscillator taken along line AA shown in FIG. 2. [Figure 5] FIG. 3 is a top view of the piezoelectric vibrating reed shown in FIG. 2 (including each electrode). [Figure 6] FIG. 2 is a bottom view of the oscillator shown in FIG. [Figure 7] FIG. 2 is a bottom view of a modified example of the oscillator shown in FIG. 1. [Figure 8] FIG. 2 is a vertical cross-sectional view showing another modified example of the oscillator shown in FIG. 1. [Figure 9]1. FIG. 4 is a diagram showing another modified example of the oscillator shown in FIG. 1, and is a top view of the oscillator in a state where the lid and the seal ring shown in FIG. 1 are removed. DETAILED DESCRIPTION OF THE INVENTION

[0027] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An oscillator according to an embodiment of the present invention will now be described with reference to the accompanying drawings. As shown in Figures 1 to 4, the oscillator 1 of this embodiment includes a package 2, a piezoelectric vibrating piece 3 mounted in the package 2, and an integrated circuit chip (an integrated circuit according to the present invention) 4 mounted in the package 2. The piezoelectric vibrating reed 3 functions as a so-called oscillator. The integrated circuit chip 4 is electrically connected to the piezoelectric vibrating reed 3 and has an oscillation circuit (not shown). The oscillation circuit has a function of generating an output signal such as a clock signal (reference signal) based on an electrical signal from the piezoelectric vibrating reed 3.

[0028] (package) The package 2 includes a package body 10 and a lid (sealing plate) 12 joined to the package body 10 via a seal ring 11 so as to overlap the package body 10 . The package body 10 and the lid 12 overlap in the thickness direction T of the package 2. In this embodiment, in a plan view seen from the thickness direction T, two directions that are perpendicular to each other are defined as a first direction L1 and a second direction L2. Furthermore, in the thickness direction T, the direction from the package 2 toward the lid 12 is defined as the upward direction, and the opposite direction is defined as the downward direction.

[0029] (Package body) The package body 10 includes a mounting substrate 20 having a first mounting surface 20a and a second mounting surface 20b that face each other in the thickness direction T, and a frame-shaped first frame 21 and a frame-shaped second frame 22 that are joined to the mounting substrate 20. The mounting substrate 20, the first frame 21, and the second frame 22 are formed from an insulating material, such as ceramic. Examples of ceramic materials include high temperature co-fired ceramics (HTCC) made of alumina and low temperature co-fired ceramics (LTCC) made of glass ceramics.

[0030] The mounting substrate 20 is a laminated substrate in which a first mounting substrate 30 and a second mounting substrate 31 are joined together vertically. The first mounting substrate 30 is a flat substrate having a predetermined thickness, and is formed in a rectangular shape in a plan view from the thickness direction T, with the length along the first direction L1 being longer than the length along the second direction L2.

[0031] The second mounting substrate 31 is disposed above the first mounting substrate 30, and is integrally bonded to the upper surface of the first mounting substrate 30 by sintering or the like while overlapping the upper surface. The second mounting substrate 31 is a flat substrate having a predetermined thickness, and is formed so that its outer shape is the same as that of the first mounting substrate 30. In the illustrated example, the second mounting substrate 31 is a substrate that is slightly thinner than the first mounting substrate 30. However, this is not limited to this, and the thickness of the second mounting substrate 31 may be changed as appropriate.

[0032] The second mounting substrate 31 has a through hole 32 formed therein, which penetrates the second mounting substrate 31 in the thickness direction T. The through hole 32 is formed in a rectangular shape whose length in the first direction L1 is longer than its length in the second direction L2 in a plan view, corresponding to the outer shape of the second mounting substrate 31. The four corners of the through hole 32 are formed in a rounded curved shape. As a result, the second mounting substrate 31 is formed in a frame shape having a through hole 32. Furthermore, a pair of mount portions 33 are formed on the inner surface of the second mounting substrate 31 in portions facing the second direction L2 so as to protrude toward the inside of the through hole 32. The pair of mount portions 33 are formed in a rectangular shape whose length in the first direction L1 is longer than its length in the second direction L2 in a plan view, and are formed in a curved shape with rounded corners.

[0033] In the mounting board 20 configured as described above, the upper surface of the second mounting board 31, including the upper surfaces of the pair of mount portions 33, functions as the first mounting surface 20a of the mounting board 20. The lower surface of the first mounting board 30 functions as the second mounting surface 20b of the mounting board 20. Furthermore, in this embodiment, the mounting substrate 20 is a laminated substrate in which the first mounting substrate 30 and the second mounting substrate 31 are laminated, but this is not limited to this case and the mounting substrate 20 may be a single-layer mounting substrate 20. In this case, for example, a pair of mounting portions 33 may be provided by forming a recessed portion recessed downward on the upper surface of the mounting substrate 20.

[0034] The first frame 21 is formed so that its outer shape is the same as that of the second mounting substrate 31 in a plan view. Therefore, the first frame 21 is formed in a frame shape that is longer in the first direction L1 than in the second direction L2. In the example shown in the figure, the first frame 21 has the same thickness as the second mounting substrate 31. However, this is not limited to this case, and the thickness of the first frame 21 may be changed as appropriate. The first frame 21 is disposed above the second mounting substrate 31, and is integrally bonded to the second mounting substrate 31 by sintering or the like in a state where it is placed on top of the upper surface of the second mounting substrate 31.

[0035] The first frame 21 is not essential and may not be provided. For example, the first frame 21 may be omitted and the second mounting substrate 31, excluding the pair of mount portions 33, may be made thicker by protruding upward. However, providing the first frame 21 makes it possible to easily form the second mounting substrate 31 from a substrate having a uniform thickness. The area (internal space) surrounded by the first frame 21 configured as described above functions as a mounting area R1 (see FIG. 4) where the piezoelectric vibrating reed 3 is mounted.

[0036] The second frame 22 is formed so that its outer shape is the same as that of the first frame 21 in a plan view. Therefore, the second frame 22 is formed in a frame shape that is longer in the first direction L1 than in the second direction L2. In the illustrated example, the second frame 22 is thicker than the first mounting substrate 30. However, this is not limited to this, and the thickness of the second frame 22 may be changed as appropriate. The second frame 22 is disposed below the first mounting substrate 30, and is integrally bonded to the lower surface of the first mounting substrate 30 by sintering or the like while being superimposed on the lower surface of the first mounting substrate 30. The area (internal space) surrounded by the second frame 22 functions as a mounting area R2 (see FIG. 4) where the integrated circuit chip 4 is mounted.

[0037] The package body 10 configured as described above is configured in the shape of a rectangular parallelepiped in which the mounting substrate 20 (first mounting substrate 30, second mounting substrate 31), the first frame 21, and the second frame 22 are stacked one above the other. The package 2 has four corners at each of which a cutout 23 is formed, which is cut out in a quarter-circular arc shape in plan view. The cutout 23 is formed over the entire package body 10 (first mounting substrate 30, second mounting substrate 31, first frame 21, and second frame 22) in the thickness direction T. The cutout 23 is formed, for example, for convenience in the manufacturing process of the package body 10.

[0038] Specifically, when manufacturing the package body 10, four wafer-like ceramic substrates for forming the first mounting substrate 30, the second mounting substrate 31, the first frame 21, and the second frame 22 are stacked and bonded together, and then a plurality of through holes are formed in a matrix pattern so as to penetrate the laminate of bonded ceramic substrates. Thereafter, the laminate of ceramic substrates is cut into a grid pattern using each through hole as a reference hole (pilot hole), thereby making it possible to manufacture a plurality of package bodies 10. During this manufacturing process, the through holes are divided into four, thereby forming the notches 23.

[0039] (seal ring, lid) A seal ring 11 is disposed above the package body 10 and is joined to the package body 10 from above. The seal ring 11 is formed in a frame shape with a predetermined thickness. Specifically, the seal ring 11 is formed so that its outer shape is slightly smaller than that of the first frame 21 and its inner shape is the same as that of the first frame 21. The seal ring 11 is joined to the upper surface of the first frame 21 around its entire periphery. Specifically, the seal ring 11 is joined integrally to the first frame 21 by baking with a brazing material such as silver brazing or a solder material, or by welding to a metal joining layer (not shown) formed on the first frame 21. The metal joining layer can be formed by, for example, electrolytic plating, electroless plating, vapor deposition, sputtering, or the like.

[0040] The material of the seal ring 11 is not particularly limited, but may be, for example, a nickel-based alloy, and specifically may be selected from Kovar, Elinvar, Invar, 42-alloy, and the like. In particular, it is preferable to select a material for the seal ring 11 that has a thermal expansion coefficient close to that of the ceramic material forming the package body 10. For example, if alumina with a thermal expansion coefficient of 6.8×10 / °C is used for the package body 10, it is preferable to use Kovar with a thermal expansion coefficient of 5.2×10 / °C or 42-alloy with a thermal expansion coefficient of 4.5 to 6.5×10 / °C for the seal ring 11.

[0041] The lid 12 is disposed above the seal ring 11 and is integrally joined to the seal ring 11 so as to cover the seal ring 11 from above. The lid 12 is, for example, a thin, flat conductive substrate, and is formed so that its outer shape is the same as that of the seal ring 11. The lid 12 is tightly bonded to the upper surface of the seal ring 11 around the entire periphery of the seal ring 11, thereby airtightly sealing the mounting area R1 of the piezoelectric vibrating reed 3. Therefore, the internal space (including the mounting area R1) surrounded by the first mounting substrate 30, the second mounting substrate 31, the first frame 21, the seal ring 11, and the lid 12 constitutes a hermetically sealed cavity C.

[0042] The method for joining the lid 12 is not particularly limited, but examples thereof include seam welding using a roller electrode, laser welding, ultrasonic welding, etc. Furthermore, in order to increase the bonding strength between the lid 12 and the seal ring 11, a bonding layer made of, for example, nickel or gold may be formed on at least the lower surface of the lid 12 and the upper surface of the seal ring 11, respectively.

[0043] (mounted electrode) On the second mounting substrate 31 constituting the package 2, a first mounting surface 20a, which is the upper surface of the pair of mounting portions 33, is provided with mounting electrodes 40 formed over the entire upper surface of each mounting portion 33. The pair of mounting electrodes 40 are electrodes that are electrically connected to a pair of excitation electrodes 60, 61, which will be described later, when the piezoelectric vibrating reed 3 is mounted. The mounting electrodes 40 may be, for example, a single-layer metal film made of a single metal, or a laminated metal film in which different metals are laminated.

[0044] The mounting electrode 40 is electrically connected to the external connection electrode 41 formed on the surface of the cutout 23. The external connection electrode 41 is formed so as to cover the surface of each of the cutouts 23 arranged at the four corners of the package body 10, and in this embodiment, is also formed over the underside of the second frame 22. However, the external connection electrode 41 does not need to be formed on both the outer surface of the cutout 23 and the underside of the second frame 22; it is sufficient if it is formed on at least one of the outer surface of the cutout 23 or the underside of the second frame 22. The external connection electrode 41 may also be, for example, a single-layer metal film made of a single metal, or a multi-layer metal film in which different metals are laminated.

[0045] The mounting electrode 40 formed on one of the mounting portions 33 is electrically connected to, for example, two of the four external connection electrodes 41, and the mounting electrode 40 formed on the other mounting portion 33 is electrically connected to the remaining two external connection electrodes 41. Furthermore, the mounting electrodes 40 and the external connection electrodes 41 are electrically connected via conductive electrodes (not shown) formed on the surfaces of the mounting substrate 20 and the second frame 22 or inside thereof.

[0046] (Piezoelectric vibrating piece) The piezoelectric vibrating reed 3 is disposed above the second mounting substrate 31 while being housed in the cavity C, and is mounted on the first mounting surface 20a, which is the upper surface of the pair of mounting portions 33. Specifically, the piezoelectric vibrating reed 3 is supported in a floating state above the upper surface of the mounting portion 33 while being electrically connected to the mounting electrode 40 via bump portions 42 such as metal bumps or conductive adhesive.

[0047] As shown in Figures 2 to 5, the piezoelectric vibrating piece 3 comprises a piezoelectric plate 50 having a pair of vibrating arms 51 arranged parallel to each other and a base 52 that integrally fixes the base ends of the pair of vibrating arms 51, and various electrodes (excitation electrodes 60, 61, mount electrodes 62, 63, weight electrodes 64, 65) formed on the outer surface of the piezoelectric plate 50. Therefore, the piezoelectric vibrating piece 3 of this embodiment is a so-called tuning fork type vibrating piece in which a pair of vibrating arms 51 vibrate when a voltage is applied. Furthermore, the piezoelectric vibrating piece 3 of this embodiment is a so-called side arm type vibrating piece having a pair of support arms (side arms) 53 formed integrally with the base 52.

[0048] The piezoelectric vibrating piece 3 is sized to fit within a mounting area R1 surrounded by the first frame 21, and is miniaturized in both the first direction L1 and the second direction L2. The piezoelectric plate 50 is made of a piezoelectric material such as quartz, lithium tantalate, or lithium niobate. For example, when the piezoelectric plate 50 is made of quartz, a Lambertian quartz ore is sliced ​​at a predetermined angle relative to the X-axis, Y-axis, and Z-axis, which are perpendicular to each other as the quartz crystal axes, to form wafers, and the wafers are then etched to form the piezoelectric plate 50.

[0049] The pair of vibrating arms 51 are arranged at an interval in the second direction L2, and are formed to extend parallel to each other along the first direction L1 from the base 52. Note that the pair of vibrating arms 51 of this embodiment are of a so-called hammerhead type, in which the width dimension of the tip end 51a side, which is the free end, is wider than the width dimension of the base end side (base 52 side), which is the fixed end. By forming the pair of vibrating arms 51 into a hammerhead type, it is possible to increase the weight of the tip end 51a of the vibrating arm 51 and the moment of inertia during vibration. Therefore, it is possible to make the vibrating arm 51 vibrate more easily, and even if the length of the vibrating arm 51 is shortened, it is possible to prevent the vibration frequency from becoming high. Therefore, it is possible to vibrate in a predetermined frequency band while miniaturizing the piezoelectric vibrating piece 3.

[0050] A vertically elongated groove 51b having a constant width is formed on the upper and lower surfaces of the pair of vibrating arms 51 that face each other in the thickness direction T, from the base end to the tip end 51a of the vibrating arm 51. As a result, the portion of the pair of vibrating arms 51 where the groove 51b is formed has an H-shaped cross section. However, the grooves 51b are not essential, and the vibrating arm 51 does not necessarily need to have the grooves 51b.

[0051] The pair of support arms 53 are formed to extend from the base 52 along the second direction L2 toward the outside of the base 52, and then extend along the first direction L1. As a result, the pair of support arms 53 are formed in an L-shape in a plan view, and are disposed outward in the second direction L2 than the pair of vibrating arms 51. Therefore, the pair of support arms 53 extend parallel to the pair of vibrating arms 51 along the first direction L1, with a gap between them.

[0052] The pair of support arms 53 are formed so that the length from the base 52 is shorter than the length of the pair of vibrating arms 51. In particular, the pair of support arms 53 are formed so as to overlap the pair of mount portions 33 from above in a plan view (see FIG. 2). This makes it possible to mount the piezoelectric vibrating reed 3 using the pair of support arms 53. Therefore, for example, there is no need to form the length of the base 52 long in the first direction L1 in order to mount the piezoelectric vibrating reed 3, and therefore the length of the piezoelectric vibrating reed 3 along the first direction L1 can be shortened accordingly. Therefore, by using a side arm type piezoelectric vibrating reed 3 that has a pair of support arms 53, the design is easy to achieve miniaturization.

[0053] As shown in FIG. 5, on the outer surface of the piezoelectric vibrating reed 3 configured as described above, various electrodes (excitation electrodes 60, 61, mount electrodes 62, 63, weight electrodes 64, 65) are patterned as described above. The excitation electrodes 60, 61 are electrodes that vibrate the pair of vibrating arms 51 at a predetermined resonance frequency in a direction (second direction L2) that moves the pair of vibrating arms 51 toward or away from each other when a voltage is applied, and are patterned and formed in a state that they are electrically separated from each other mainly on the outer surfaces of the pair of vibrating arms 51. Specifically, one excitation electrode 60 is formed mainly over the side surfaces and upper and lower surfaces of one vibrating arm 51, and is also formed within the groove 51b and over the upper and lower surfaces of the other vibrating arm 51. The other excitation electrode 61 is formed mainly within the groove 51b and over the upper and lower surfaces of one vibrating arm 51, and is also formed over the side surfaces and upper and lower surfaces of the other vibrating arm 51.

[0054] The mount electrodes 62, 63 are formed on the outer surfaces of the pair of support arms 53. Specifically, one mount electrode 62 is formed on the outer surface of one support arm 53, and the other mount electrode 63 is formed on the outer surface of the other support arm 53. Furthermore, a pair of mount electrodes 62, 63 are also formed on the base 52 so as to be electrically connected to the pair of excitation electrodes 60, 61 via the base 52. Specifically, one mount electrode 62 is electrically connected to one excitation electrode 60, and the other mount electrode 63 is electrically connected to the other excitation electrode 61.

[0055] The weight electrodes 64 and 65 are formed on the outer surfaces of the tip portions 51a (head portions) of the pair of vibrating arms 51, and are formed so as to be electrically connected to the excitation electrodes 60 and 61, respectively. The weight electrodes 64, 65 function as adjustment electrode films that are mainly used when adjusting the frequency of the piezoelectric vibrating reed 3. For example, during the assembly process of the oscillator 1, a voltage is applied to the piezoelectric vibrating reed 3 using a monitor electrode 82, which will be described later, to vibrate the pair of vibrating arms 51 and check the vibration status. Then, depending on the difference between the measured actual frequency and a preset target frequency, the weight electrodes 64, 65 can be partially removed by laser trimming or the like, thereby adjusting the frequency band of the piezoelectric vibrating reed 3 to fall within the target frequency band. However, the weight electrodes 64, 65 are not essential and may be omitted.

[0056] 2 to 4, the piezoelectric vibrating reed 3 configured as described above has a pair of support arms 53 mounted on a pair of mount portions 33 via bump portions 42. As a result, the piezoelectric vibrating reed 3 is supported in a state where it is suspended above the upper surfaces of the pair of mount portions 33 while housed in the cavity C. Furthermore, a pair of mount electrodes 62, 63 are electrically connected to the mounting electrode 40 via the bump portions 42. Therefore, the pair of excitation electrodes 60, 61 and the mounting electrode 40 are electrically connected through the bump portions 42 and the mount electrodes 62, 63.

[0057] (integrated circuit chip) 3 and 4, the integrated circuit chip 4 is disposed below the first mounting substrate 30, and is mounted on the second mounting surface 20b, which is the lower surface of the first mounting substrate 30, in a state where it is disposed within a mounting region R2 surrounded by the second frame 22. Specifically, the integrated circuit chip 4 is mounted on the second mounting surface 20b via bump portions (not shown), such as metal bumps or conductive adhesive. The integrated circuit chip 4 is formed in a rectangular parallelepiped shape in plan view, with a length in the first direction L1 that is longer in the second direction L2, corresponding to the shape of the package 2. Note that the illustration of the integrated circuit chip 4 is simplified in each drawing.

[0058] As described above, the integrated circuit chip 4 has at least an oscillator circuit (not shown) that generates an output signal based on an electrical signal from the piezoelectric vibrating reed 3. Furthermore, a plurality of integrated circuit terminals 80 are provided so as to be exposed on the top surface of the integrated circuit chip 4 (see FIG. 3). The integrated circuit terminals 80 are not particularly limited, but may be, for example, a power input terminal, a signal output terminal, a signal terminal that is electrically connected to the piezoelectric vibrating reed 3, a ground terminal, a switch signal input terminal, etc.

[0059] In this embodiment, an example is given in which four integrated circuit terminals 80 are provided near the four corners of the integrated circuit chip 4, but this is not limited to this case, and the number and formation positions of the integrated circuit terminals 80 may be changed as appropriate.

[0060] (Integrated circuit electrodes, monitor electrodes) As shown in Figures 4 and 6, a plurality of integrated circuit electrodes 81 and monitor electrodes 82 are formed on the second mounting surface 20b, which is the underside of the first mounting substrate 30, in a portion located inside the second frame 22. The integrated circuit electrodes 81 are formed at positions overlapping from above the integrated circuit terminals 80 formed on the integrated circuit chip 4. As a result, the multiple integrated circuit electrodes 81 are electrically connected to the multiple integrated circuit terminals 80. The integrated circuit electrodes 81 are not particularly limited, but examples thereof include power supply electrodes electrically connected to power supply input terminals, signal output electrodes electrically connected to signal output terminals, signal electrodes electrically connected to signal terminals, ground electrodes electrically connected to ground terminals, and switch electrodes electrically connected to switch signal input terminals.

[0061] In this embodiment, four integrated circuit electrodes 81 are formed on the second mounting surface 20b of the first mounting substrate 30 in correspondence with the four integrated circuit terminals 80. Therefore, the four integrated circuit electrodes 81 are arranged at intervals in the first direction L1 and the second direction L2. However, the number and formation positions of the integrated circuit electrodes 81 may be changed as appropriate in correspondence with the integrated circuit terminals 80. The integrated circuit electrodes 81 are electrically connected to the mounting electrodes 40 and external connection electrodes 41 via conductive electrodes (not shown) formed on the surfaces of or inside the mounting substrate 20 and second frame 22 .

[0062] A pair of monitor electrodes 82 are provided corresponding to the mounting electrodes 40. The monitor electrodes 82 are arranged at an interval in the second direction L2 and are arranged so as to be located between adjacent integrated circuit electrodes 81 in the first direction L1. In particular, the monitor electrodes 82 are formed to have an area equal to or smaller than the area of ​​the integrated circuit electrodes 81. The monitor electrode 82 is electrically connected to the pair of mounting electrodes 40 via conductive electrodes (not shown) formed on the surfaces of or inside the mounting substrate 20 and the second frame 22, respectively.

[0063] (Capacity suppression part) In the oscillator 1 configured as described above, as shown in Figures 4 and 6, in a plan view seen from the thickness direction T, a capacitance suppression section 70 is provided in an overlapping region W where a plurality of integrated circuit electrodes 81 formed on the second mounting surface 20b of the first mounting substrate 30 and a pair of mounting electrodes 40 formed on the first mounting surface 20a, which is the upper surface of the mount section 33, overlap each other. The capacitance suppression section 70 suppresses stray capacitance generated between the integrated circuit electrodes 81 and the mounting electrodes 40 in the overlapping region W.

[0064] The capacitance suppressing portion 70 has a non-electrode portion 71 formed on the integrated circuit electrode 81 so as to reduce the area of ​​the overlapping portion of the integrated circuit electrode 81 that overlaps with the mounting electrode 40 in a plan view seen from the thickness direction T. The non-electrode portion 71 is formed in a notch shape that recesses the outer shape of the integrated circuit electrode 81 inward. In particular, the non-electrode portion 71 of this embodiment is formed so as to completely eliminate the overlapping portion.

[0065] (Oscillator action) Next, the operation of the oscillator 1 configured as above will be described. The oscillator 1 is mounted on, for example, a control board of an electronic device (not shown) for use. In this case, the oscillator 1 can be mounted in a state where the external connection electrodes 41 are electrically connected to the terminals of the control board using external electrodes such as metal bumps or solder (not shown).

[0066] 2, by applying a predetermined drive voltage to the external connection electrode 41 of the oscillator 1 mounted in this manner, a current can be passed through the excitation electrodes 60, 61 of the pair of vibrating arm portions 51 via the pair of mounting electrodes 40. This allows the pair of vibrating arm portions 51 to vibrate in a predetermined resonance frequency band in a direction in which they approach or move away from each other (second direction L2) by utilizing the interaction between the excitation electrodes 60, 61, and can also be converted into an electric signal by the piezoelectric property. Therefore, an output signal such as a clock signal can be generated based on the electrical signal by utilizing the oscillation circuit of the integrated circuit chip 4. This allows the output signal to be used as, for example, a time source, a timing source for control signals, a reference signal source, etc., and can function as the oscillator 1.

[0067] In particular, with respect to the relationship between the mounting electrodes 40 formed on the first mounting surface 20a, which is the upper surface of the pair of mounting portions 33, and the multiple integrated circuit electrodes 81 formed on the second mounting surface 20b, which is the lower surface of the first mounting substrate 30, as shown in Fig. 6, a capacitance suppressing portion 70 including an electrode non-forming portion 71 is provided in an overlapping region W where the integrated circuit electrodes 81 and the mounting electrodes 40 overlap each other in the thickness direction T. Therefore, even if the mounting electrodes 40 and the integrated circuit electrodes 81 are arranged close to each other in the thickness direction T, as shown in Fig. 4, the stray capacitance generated between the mounting electrodes 40 and the integrated circuit electrodes 81 in the overlapping region W can be suppressed.

[0068] Therefore, even if the oscillator 1 itself is made smaller and thinner, it is possible to suppress deterioration of voltage characteristics due to the influence of stray capacitance, and it is possible to vibrate the piezoelectric vibrating reed 3 with stable frequency characteristics. Therefore, it is possible to stably generate an output signal, and it is possible to provide an oscillator 1 with high operational reliability.

[0069] 6, in particular, the non-electrode portion 71 is formed in a notch shape that recesses the outer shape of the integrated circuit electrode 81 inward so as to remove a portion of the integrated circuit electrode 81. This makes it possible to reduce the area of ​​the overlapping portion that overlaps with the mounting electrode 40 by the simple method of simply forming the non-electrode portion 71 on the integrated circuit electrode 81 itself. Moreover, because the non-electrode portion 71 is formed to completely eliminate the overlapping portion, it is possible to prevent the mounting electrode 40 and the integrated circuit electrode 81 from overlapping each other in a plan view seen in the thickness direction T. Therefore, it is possible to suppress the occurrence of stray capacitance between the mounting electrode 40 and the integrated circuit electrode 81. As a result, the piezoelectric vibrating reed 3 can be vibrated with more stable frequency characteristics, and the operational reliability of the oscillator 1 can be further improved.

[0070] Furthermore, since the oscillator 1 of this embodiment is equipped with the monitor electrode 82, during the assembly process of the oscillator 1, the monitor electrode 82 can be used to supply current to the excitation electrodes 60, 61 via the mounting electrode 40, making it possible to check the vibration status of the piezoelectric vibrating reed 3. Therefore, by trimming the weight electrodes 64, 65 as necessary, the vibration of the piezoelectric vibrating reed 3 can be adjusted so that it vibrates in a predetermined frequency band. This allows for further improvement in operational reliability.

[0071] The vibration adjustment process for the piezoelectric vibrating reed 3 may be performed before the integrated circuit chip 4 is mounted in the package 2, or may be performed after the integrated circuit chip 4 is mounted in the package 2.

[0072] In particular, the area of ​​the monitor electrode 82 is the same as or smaller than that of the integrated circuit electrode 81, so it is possible to form a larger integrated circuit electrode 81. Therefore, even when the non-electrode portion 71 is formed on the integrated circuit electrode 81, the integrated circuit electrode 81 can have a sufficient area and can properly function as an electrode.

[0073] (Modified oscillator) In the above embodiment, an example was given in which a cutout-shaped non-electrode portion 71 is formed in the integrated circuit electrode 81 so as to completely eliminate the overlapping portion of the integrated circuit electrode 81 that overlaps with the mounting electrode 40 when viewed in a plan view from the thickness direction T, but the present invention is not limited to this case. For example, as shown in FIG. 7, rather than completely eliminating the overlapping portion of the integrated circuit electrode 81 that overlaps with the mounting electrode 40 in a plan view seen from the thickness direction T, a notched non-electrode portion 71 may be formed to reduce the area of ​​the overlapping portion.

[0074] Even in this case, it is possible to suppress the stray capacitance occurring between the mounting electrode 40 and the integrated circuit electrode 81 in the overlapping region W compared to when the electrode-free portion 71 is not provided. Therefore, it is possible to suppress the deterioration of voltage characteristics caused by the influence of stray capacitance, and it is possible to vibrate the piezoelectric vibrating reed 3 with stable frequency characteristics.

[0075] The electrode-free portion 71 is not limited to a notch-like portion that recesses the outer shape of the integrated circuit electrode 81 inward. For example, the electrode-free portion 71 may be formed in the integrated circuit electrode 81 as an opening surrounded by the integrated circuit electrode 81.

[0076] (Modified oscillator) Furthermore, in the above embodiment, the capacitance suppressing portion 70 is configured to include the electrode-free portion 71 formed on the integrated circuit electrode 81, but the present invention is not limited to this case. 8 , in an overlapping region W where the integrated circuit electrode 81 and the mounting electrode 40 overlap each other in a plan view seen from the thickness direction T, an insulating film 72 may be formed on the second mounting surface 20b, which is the lower surface of the first mounting substrate 30. The insulating film 72 is formed so as to be located between the second mounting surface 20b and the integrated circuit electrode 81. In this case, it is not necessary to form the electrode-free portion 71 on the integrated circuit electrode 81.

[0077] Even in this case, the insulating film 72 can be used to suppress the occurrence of stray capacitance between the mounting electrode 40 and the integrated circuit electrode 81 in the overlapping region W. Therefore, the piezoelectric vibrating reed 3 can be vibrated with stable frequency characteristics, further improving the operational reliability of the oscillator 1. In particular, this method requires only a simple method of forming the insulating film 72, and does not require changing the shape of the integrated circuit electrode 81 itself, leading to efficient manufacturing. Even when the insulating film 72 is provided, the electrode-free portion 71 may be further formed on the current collecting circuit electrode.

[0078] Although the embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. The embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. The embodiments and their modifications include, for example, those that can be easily imagined by a person skilled in the art, those that are substantially the same, and those that are equivalent.

[0079] For example, in the above embodiment, a side arm type piezoelectric vibrating reed 3 having a pair of support arms 53 has been described as an example, but the pair of support arms 53 is not essential, and a piezoelectric vibrating reed 3 having a base 52 and a pair of vibrating arms 51 may also be used. In this case, mount electrodes 62, 63 may be formed on the base 52, and the mounting electrode 40 may be disposed in a position facing the mount electrodes 62, 63 in the vertical direction. In addition, in the above embodiment, a hammerhead type piezoelectric vibrating piece 3 was used as an example, but this is not limited to this case, and a piezoelectric vibrating piece 3 in which the width of the vibrating arm portion 51 is constant from the base end to the tip end 51a may also be used.

[0080] Furthermore, in the above embodiment, a tuning fork-type vibrating piece having a pair of vibrating arms 51 has been described as an example of the piezoelectric vibrating piece 3, but the present invention is not limited to this. For example, a piezoelectric vibrating piece (a so-called AT-cut vibrating piece) formed by AT-cutting quartz crystal and having thickness-shear vibration as its main vibration may be used. Even in this case, the mounting electrodes may be disposed at positions facing the mount electrodes of the AT-cut vibrating element vertically.

[0081] Furthermore, in the above embodiment, the case where the electrode-free portion 71 is formed on the integrated circuit electrode 81 has been described as an example, but the present invention is not limited to this case. For example, as shown in Fig. 9, the electrode-free portion 90 may be formed on the mounting electrode 40 in the overlap region W to function as the capacitance suppression portion 70. In the illustrated example, the electrode-free portion 90 is formed in a notched shape that recesses the outer shape of the mounting electrode 40 inward so as to remove a portion of the mounting electrode 40, and is formed so as to completely eliminate the overlapping portion with the integrated circuit electrode 81. Even in this case, it is possible to suppress the occurrence of stray capacitance between the mounting electrode 40 and the integrated circuit electrode 81. Therefore, the piezoelectric vibrating reed 3 can be vibrated with more stable frequency characteristics, and the operational reliability of the oscillator 1 can be further improved. Even in this case, the electrode-free portion 90 may be formed in an opening shape surrounded by the mounting electrode 40, for example.

[0082] The present invention further includes the following aspects. <1> a package including a mounting substrate having a first mounting surface and a second mounting surface facing each other in a thickness direction; a piezoelectric vibrating piece mounted on the first mounting surface; an integrated circuit having a plurality of integrated circuit terminals and mounted on the second mounting surface; a mounting electrode that is electrically connected to an excitation electrode of the piezoelectric vibrating piece is formed on the first mounting surface; a plurality of integrated circuit electrodes electrically connected to the integrated circuit terminals are formed on the second mounting surface; An oscillator characterized in that, in a planar view seen from the thickness direction, an overlapping region where the integrated circuit electrode and the mounting electrode overlap each other is provided with a capacitance suppression portion that suppresses stray capacitance that occurs between the integrated circuit electrode and the mounting electrode in the overlapping region. <2> <1> In the oscillator described in An oscillator, wherein the capacitance suppression portion includes a non-electrode portion formed on the integrated circuit electrode so as to reduce the area of ​​the overlapping portion of the integrated circuit electrode that overlaps with the mounting electrode in a planar view from the thickness direction. <3> <1> In the oscillator described in The capacitance suppression portion includes a non-electrode portion formed on the mounting electrode so as to reduce the area of ​​the overlapping portion of the mounting electrode that overlaps with the integrated circuit electrode in a planar view from the thickness direction. <4> <2> or <3> In the oscillator described in The non-electrode portion is formed so as to eliminate the overlapping portion. <5> <1> from <4> In the oscillator according to any one of the above items, an oscillator, wherein the capacitance suppressing portion includes an insulating film formed on the second mounting surface so as to be located between the second mounting surface and the integrated circuit electrode; <6> <1> from <5> In the oscillator according to any one of the above items, a monitor electrode electrically connected to the mounting electrode is formed on the second mounting surface; The oscillator is configured such that the monitoring electrode has an area equal to or smaller than that of the integrated circuit electrode. <7> <1> from <6> In the oscillator according to any one of the above items, The piezoelectric vibrating piece is a piezoelectric plate having a pair of vibrating arms arranged parallel to each other and a base portion integrally fixing the base ends of the vibrating arms; an excitation electrode formed on an outer surface of the piezoelectric plate, the excitation electrode causing the pair of vibrating arms to vibrate when a voltage is applied thereto. [Explanation of symbols]

[0083] W…Overlapping area 1...Oscillator 2. Package 3...Piezoelectric vibrating piece 4...Integrated circuit chip (integrated circuit) 20...Mounting board 20a...first mounting surface of mounting board 20b...Second mounting surface of mounting board 40...Mounted electrode 50...Piezoelectric plate 51...Vibrating arm part 52...Base 60, 61...excitation electrode 70...Capacity suppression section 71, 90...electrode non-forming part 72...insulating film 80...Integrated circuit terminal 81...Integrated circuit electrode 82...Monitor electrode

Claims

1. a package including a mounting substrate having a first mounting surface and a second mounting surface facing each other in a thickness direction; a piezoelectric vibrating piece mounted on the first mounting surface; an integrated circuit having a plurality of integrated circuit terminals and mounted on the second mounting surface, a mounting electrode that is electrically connected to an excitation electrode of the piezoelectric vibrating piece is formed on the first mounting surface; a plurality of integrated circuit electrodes electrically connected to the integrated circuit terminals are formed on the second mounting surface; An oscillator characterized in that, in a planar view seen from the thickness direction, an overlapping region where the integrated circuit electrode and the mounting electrode overlap each other is provided with a capacitance suppression portion that suppresses stray capacitance that occurs between the integrated circuit electrode and the mounting electrode in the overlapping region.

2. 2. The oscillator according to claim 1, An oscillator, wherein the capacitance suppression portion includes a non-electrode portion formed on the integrated circuit electrode so as to reduce the area of ​​the overlapping portion of the integrated circuit electrode that overlaps with the mounting electrode in a planar view from the thickness direction.

3. 2. The oscillator according to claim 1, The capacitance suppression portion includes a non-electrode portion formed on the mounting electrode so as to reduce the area of ​​the overlapping portion of the mounting electrode that overlaps with the integrated circuit electrode in a planar view from the thickness direction.

4. 4. The oscillator according to claim 2, The non-electrode portion is formed so as to eliminate the overlapping portion.

5. 2. The oscillator according to claim 1, an oscillator, wherein the capacitance suppressing portion includes an insulating film formed on the second mounting surface so as to be located between the second mounting surface and the integrated circuit electrode;

6. 2. The oscillator according to claim 1, a monitor electrode electrically connected to the mounting electrode is formed on the second mounting surface; The oscillator is configured such that the monitoring electrode has an area equal to or smaller than that of the integrated circuit electrode.

7. 2. The oscillator according to claim 1, The piezoelectric vibrating piece is a piezoelectric plate having a pair of vibrating arms arranged parallel to each other and a base portion integrally fixing the base ends of the vibrating arms; an excitation electrode formed on an outer surface of the piezoelectric plate, the excitation electrode causing the pair of vibrating arms to vibrate when a voltage is applied thereto.

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