JP4437694B2 - Piezoelectric oscillator manufacturing method, piezoelectric oscillator, and electronic device - Google Patents

Description

  The present invention relates to a method for manufacturing a piezoelectric oscillator, a piezoelectric oscillator, and an electronic device.

Piezoelectric oscillators are used in various electronic devices for the purpose of obtaining a constant frequency signal in an electronic circuit. In recent years, as electronic devices have been reduced in size, piezoelectric oscillators have also been reduced in thickness and size. FIG. 12 shows a cross-sectional view of a piezoelectric oscillator according to the prior art. The piezoelectric oscillator 100 according to the prior art includes an IC chip 101 mounted on a lead frame 102, a circuit component 104 in which the periphery of the IC chip 101 is covered with a resin 103, and a piezoelectric vibrating piece 105 mounted on a ceramic package base 106. The piezoelectric vibrator 108 in which the package base 106 is hermetically sealed with a metallic lid 107 is arranged vertically, and the circuit component 104 and the piezoelectric vibrator 108 are electrically and mechanically connected (patent). Reference 1).
JP 2001-332932 A

  However, a piezoelectric oscillator having a configuration in which a piezoelectric vibrator having a piezoelectric vibrating piece mounted on a package and a circuit component are vertically connected has a problem that it cannot be reduced by the thickness of the package base. In other words, the strength of the package base decreases as the ceramic thickness of the package base decreases, so the ceramic needs to be thick enough to secure this strength. There was a problem that could not be made thinner.

  If the piezoelectric oscillator is a temperature-compensated piezoelectric oscillator, the temperature of the piezoelectric vibrating piece can be measured more accurately as the temperature sensor is placed closer to the piezoelectric vibrating piece. As a result, the distance between the temperature sensor and the piezoelectric vibrating piece is increased, which makes it difficult to perform accurate temperature compensation.

  Furthermore, piezoelectric oscillators are manufactured separately from a piezoelectric vibrator and an integrated circuit chip, and only non-defective products are combined. However, when a piezoelectric vibrator and an integrated circuit chip are combined, the piezoelectric oscillator varies due to variations in load capacity on the integrated circuit side. The oscillation frequency of the oscillator sometimes deviated from the reference frequency. In this case, the oscillation frequency of the piezoelectric oscillator is adjusted by adjusting the capacitance on the integrated circuit chip side. However, when adjusting the capacitance with a capacitor array (multiple capacitors) provided on the integrated circuit chip, the size of the integrated circuit chip is limited, so the number of capacitors mounted on the integrated circuit chip is limited, and oscillation occurs. There was a problem that the frequency could not be adjusted accurately.

The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a piezoelectric oscillator manufacturing method and a piezoelectric oscillator that can be reduced in thickness.
Another object of the present invention is to provide an electronic device equipped with a piezoelectric oscillator that can be made thin.

  In order to achieve the above object, a method for manufacturing a piezoelectric oscillator according to the present invention is formed by being bent on one side, formed with a connection lead provided with a connection terminal, and bent on the other side. A step of forming a multilayer lead frame having mounting leads having mounting terminals to be bonded to the substrate; mounting an electronic component on the multilayer lead frame; and electrically connecting the multilayer lead frame and the electronic component A step of exposing the surfaces of the connection terminal and the mounting terminal to mold-sealing the laminated lead frame and the electronic component, and a step of mounting a piezoelectric vibrating piece on the connection terminal via a conductive material And a step of covering the piezoelectric vibrating piece with a lid and hermetically sealing the same. In this case, the step of mounting the piezoelectric vibrating piece may include a step of adjusting the oscillation frequency of the piezoelectric vibrating piece.

  As a result, a thin piezoelectric oscillator can be manufactured. Further, after the step of joining the lid to the mold package, a step of adjusting the frequency of the piezoelectric oscillator by changing the capacitance of the capacitor provided in the electronic component or the voltage supplied to the variable capacitance diode may be provided. In this case, since the frequency adjustment of the piezoelectric oscillator is a two-stage adjustment method after the piezoelectric vibrating piece is mounted on the mold package and after the lid is joined to the mold package, it can be accurately adjusted to a desired frequency. In addition, if the piezoelectric resonator element is mounted on the mold package and then adjusted to the desired frequency by adjusting the electrode thickness of the piezoelectric resonator element, the amount of frequency adjustment when adjusting the frequency on the electronic component side is small. That's it. Therefore, the burden of frequency adjustment on the electronic component side can be reduced.

The piezoelectric oscillator according to the present invention includes a piezoelectric vibrating piece, a lead frame on which a connection terminal having a connection surface on which the piezoelectric vibrating piece is mounted is formed, and the lead frame is sealed while exposing at least the connection surface. A molded package and a lid that covers the piezoelectric vibrating piece and is airtightly bonded to the molded package , wherein the lead frame is at least two laminated lead frames, and one of the lead frames A connecting lead is formed on the other lead frame, a mounting lead is formed on the other lead frame, and at least one of the connecting lead and the mounting lead is bent to the opposite side of the laminated surface. It is characterized by. Since the connection terminal and the mounting terminal are arranged so as to overlap each other, the package and the piezoelectric vibrating piece can be arranged so as to overlap each other. Therefore, the piezoelectric oscillator can be further reduced in thickness.

The piezoelectric oscillator according to the present invention is a piezoelectric oscillator having a plurality of leads formed from a lead frame, and terminals formed on the plurality of leads and spaced apart from each other are arranged in a plurality of stages in the vertical direction of the package. The lead frame includes at least a connecting terminal on which a piezoelectric vibrating piece is mounted , the lead frame is a laminated lead frame of at least two sheets, and a connecting lead is formed on one of the lead frames, and the other A mounting lead is formed on the lead frame, and one of the connecting lead and the mounting lead is bent to the opposite side of the laminated surface . Accordingly, since the piezoelectric vibrating piece is not accommodated in the package, the piezoelectric oscillator can be thinned. Further, by arranging the terminals in a plurality of stages in the vertical direction of the package, it is not necessary to arrange the terminals in a planar manner, the planar size can be reduced, and the piezoelectric oscillator can be miniaturized.

An upper lead frame that raises the connection lead to one side and serves as a connection terminal to the piezoelectric vibrating piece, and a lower lead frame that raises the mounting lead to the other side and serves as a mounting terminal to the mounting board The laminated lead frame and the electronic component are sealed while exposing the laminated lead frame, the electronic component mounted on the laminated lead frame, the connection surface of the connection terminal, and the mounting surface of the mounting terminal. A mold package, a piezoelectric vibrating piece mounted on a connection surface of the connection terminal, and a lid body that covers the piezoelectric vibrating piece and is airtightly joined to the mold package. As a result, the piezoelectric vibrating piece can be mounted on the mold package including the electronic components, so that the piezoelectric oscillator can be reduced in size.

  Further, the mold package is characterized in that a moisture-resistant material is applied to the surface where the connection terminals are exposed. Accordingly, moisture does not enter the space where the piezoelectric vibrating piece is sealed via the package, and thus the piezoelectric vibrating piece can be hermetically sealed. Since the oscillation frequency of the piezoelectric oscillator does not change, a desired frequency can be obtained.

  Further, on the side of the mold package on which the connection terminal is provided, a convex portion that protrudes toward the piezoelectric vibrating piece side is formed by a connection terminal that is not used for mounting the molding material or the piezoelectric vibrating piece of the mold package. The convex portion is a means for supporting the piezoelectric vibrating piece. As a result, even if an impact is applied to the piezoelectric oscillator due to dropping or the like, the piezoelectric vibrating piece is supported by the support means, so that it is not greatly shaken, and cracking or chipping does not occur in the piezoelectric vibrating piece. Therefore, a highly reliable piezoelectric oscillator can be obtained.

  Further, the connection terminal is characterized in that a concave portion is formed in the exposed connection surface. As a result, not only can the piezoelectric vibrating piece be mounted on the connection terminal using a conductive material such as a conductive adhesive, but also the piezoelectric vibrating piece can be mounted on the connection terminal using a conductive material such as a metal ball.

Further, the mounting terminal is characterized in that a recessed portion or a protruding portion is formed on the exposed mounting surface. Accordingly, the contact area between the bonding material for bonding the mounting terminal and the mounting substrate and the mounting surface of the mounting terminal can be increased, and the bonding strength can be increased.
An electronic apparatus according to the present invention is characterized by mounting the above-described piezoelectric oscillator. As a result, the piezoelectric oscillator having the above-described features can be mounted on an electronic device.

Hereinafter, preferred embodiments of a method for manufacturing a piezoelectric oscillator, a piezoelectric oscillator, and an electronic device according to the present invention will be described. In addition, what is described below is only one aspect | mode of embodiment of this invention, and this invention is not limited to these. FIG. 1 is an exploded perspective view of the piezoelectric oscillator according to the present embodiment. FIG. 2 is a cross-sectional view taken along line AA in FIG. In FIG. 1, the mold package and the lid are omitted. In the piezoelectric oscillator 10 according to the present embodiment, the connection lead 12 is raised to one side and the upper lead frame 18 to be the connection terminal 16 with the piezoelectric vibrating piece 14 and the mounting lead 20 are raised to the other side. This is a configuration including a laminated lead frame in which a lower lead frame 24 serving as a mounting terminal 22 with a mounting substrate (not shown) is laminated. Further, an electronic component mounted on the multilayer lead frame, and a mold package 26 that seals the multilayer lead frame and the electronic component while exposing the connection surface of the connection terminal 16 and the mounting surface of the mounting terminal 22; The piezoelectric vibration piece 14 mounted on the connection surface of the connection terminal 16 and a lid 28 that covers the piezoelectric vibration piece 14 and is airtightly joined to the mold package 26. The electronic component is a circuit for causing the piezoelectric vibrating piece 14 to oscillate, and is formed as an IC chip 30. Moreover, you may mount resistance, a capacitor | condenser, etc. as an electronic component.

  FIG. 3 shows a plan view of the lead frame. 3A is a plan view of the upper lead frame 18, and FIG. 3B is a plan view of the lower lead frame 24. In the piezoelectric oscillator 10 according to the present embodiment, two lead frames are overlapped to form a laminated lead frame. Each lead frame is formed by providing a cross-shaped frame portion 32 (32a, 32b) on a conductive metal sheet and forming the same pattern inside each frame portion 32. In the upper lead frame 18 shown in FIG. 3A, leads 12 for connection to the piezoelectric vibrating piece 14 are formed at the four corners inside the frame portion 32a. Since two connection electrodes 34 are formed on the piezoelectric vibrating piece 14, at least two connection leads 12 may be formed on the upper lead frame 18. When two connection leads 12 are provided, the mounting area of the IC chip 30 can be increased by the amount that the connection leads that do not contribute to the mounting of the piezoelectric vibrating piece 14 are not provided. Therefore, the outer shape of the IC chip 30 can be increased, and a function such as a frequency dividing function of an output signal can be added to the increased portion.

  Further, a wire bonding pad 36 is formed at the inner end of each connection lead 12 in the long side direction of the frame portion 32a. In order to support the pad 36 on the same surface as the frame portion 32a, the pad 36 is connected to the long side of the frame portion 32a. Thereby, the connecting lead 12 is fixed to the frame portion 32a. On the other hand, an inclined portion 38 is formed outside the pad 36 in the long side direction of the frame portion 32 a, and the connection terminal 16 is formed outside the inclined portion 38. Then, by forming the inclined portion 38 from the pad 36, the connection terminals 16 are arranged in parallel at a predetermined distance from the upper lead frame 18. The predetermined distance is a distance larger than the maximum height of the wire 40 bonded to the IC chip 30.

  The lower lead frame 24 shown in FIG. 3B has mounting leads 20 for mounting with a mounting board at four corners inside the frame portion 32b. Further, a wire bonding pad 42 is formed at the inner end of each mounting lead 20 in the short side direction of the frame portion 32b. In order to support the pad 42 on the same plane as the frame portion 32b, the pad 42 is connected to the short side of the frame portion 32b. Thus, the mounting lead 20 is fixed to the frame portion 32b. On the other hand, an inclined portion 44 is formed outside the pad 42 in the short side direction of the frame portion 32 b, and the mounting terminal 22 is formed outside the inclined portion 44. Then, by lowering the inclined portion 44 from the pad 42, the mounting terminals 22 are arranged in parallel at a predetermined distance from the lower lead frame 24.

  Further, in the middle portion of each mounting lead 20 in the short side direction of the frame portion 32 b of the lower lead frame 24, the characteristic inspection of the IC chip 30, the characteristic adjustment and / or the conduction check between the piezoelectric vibrator and the connection terminal 16 are performed. An adjustment terminal 46 is formed for this purpose. The characteristic inspection refers to an operation check of the IC chip 30 after molding, a characteristic inspection as the piezoelectric oscillator 10, and the like. The characteristic adjustment means that when a temperature compensation circuit is added to the IC chip 30, a function for correcting a frequency change due to the temperature of the piezoelectric oscillator 10 or a function for changing the frequency by an input voltage is added to the IC chip 30. In addition, it means adjusting the change sensitivity. The adjustment terminal 46 is connected to the short side of the frame portion 32 b and is supported on the same plane as the lower lead frame 24. Since the mounting terminal 22 is arranged at a predetermined distance from the lower lead frame 24 to the lower side, the adjustment terminal 46 does not short-circuit with the electrode of the mounting board.

  Further, a die pad 48 is formed at the center of the frame portion 32 b in the lower lead frame 24. The die pad 48 is connected to the long side of the frame portion 32 b and is supported on the same plane as the lower lead frame 24. The adjustment terminal 46 and the die pad 48 may be formed on the upper lead frame 18. Further, the positions at which the connection terminal 16, the mounting terminal 22, the adjustment terminal 46, and the die pad 48 are connected to the frame portions 32a and 32b are not limited to the long side or the short side. For example, when the number of adjustment terminals 46 is large, the adjustment terminals 46 are connected to the long side, and the die pad 48 is connected to the short side.

  Then, the upper lead frame 18 and the lower lead frame 24 are overlapped to form a laminated lead frame. The upper lead frame 18 and the lower lead frame 24 are fixed to each frame portion 32 by spot welding or the like. In addition, inside the frame portion 32, each lead of each lead frame is formed so that the upper lead frame 18 and the lower lead frame 24 do not come into contact with each other. As a result, the laminated lead frame is formed with terminals spaced apart from each other in two stages in the vertical direction. That is, the laminated lead frame is arranged in a state where the connection terminals 16 and the mounting terminals 22 are overlapped at the same position in plan view. For example, an iron alloy or a copper alloy is used as the material of the upper lead frame 18 and the lower lead frame 24.

  The IC chip 30 is mounted on the upper surface of the die pad 48 provided on the lower lead frame 24 via an adhesive. Note that a temperature compensation circuit and a voltage control circuit can be added to the IC chip 30 according to the embodiment. A plurality of terminals are provided on the upper surface of the IC chip 30, and each terminal and each terminal of the laminated lead frame are electrically connected. Specifically, the pads of the connection terminals 16, the pads of the mounting terminals 22, and the adjustment terminals 46 are connected to the respective terminals on the upper surface of the IC chip 30 by wire bonding. Since the notch 50 is provided in the connecting lead 12 to form an L shape, the pad of the mounting terminal 22 is exposed upward, and wire bonding can be performed on this pad. The IC chip 30 can also be mounted on a laminated lead frame by performing flip chip bonding. That is, the laminated lead frame has a configuration in which the die pad 48 is not provided on the lower lead frame 24, the pad of the connection terminal 16, the pad of the mounting terminal 22, and the adjustment terminal 46 are extended in the center and formed on the same plane. . Then, each terminal of the IC chip 30 may be directed downward, and each terminal may be connected to the pad of the connection terminal 16, the pad of the mounting terminal 22, and the adjustment terminal 46 by flip chip bonding. The IC chip 30 can also be provided on the lower surface of the die pad 48. Further, the IC chip 30 may be mounted on either the upper surface or the lower surface of the die pad 48, and an electronic component such as a chip capacitor may be mounted on the other surface.

  Next, the laminated lead frame and the IC chip 30 are molded and sealed in the mold package 26. Specifically, the laminated lead frame on which the IC chip 30 is mounted is placed in a resin mold, and a mold package 26 is formed by injection-molding a thermosetting resin such as an epoxy resin in the mold. . The mold package 26 is formed inside the frame portion 32 of each lead frame. At this time, the connection surface of the connection terminal 16 to which the connection electrode 34 of the piezoelectric vibrating piece 14 is connected via the conductive material 54, and the mounting surface of the mounting terminal 22 connected to the electrode pattern of the mounting substrate via the bonding material Are exposed on the surface of the mold package 26. In order to expose the connection surface of the connection terminal 16 and the mounting surface of the mounting terminal 22 to the surface of the mold package 26, the resin may be injection-molded in a state of being in surface contact with the upper surface and the lower surface of the resin molding die. By the way, resin may enter between the connection surface of the connection terminal 16 and the mounting surface of the mounting terminal 22 and the resin molding die due to the injection pressure of the resin, and the resin may adhere to the connection surface and the mounting surface. In this case, a liquid containing an abrasive may be sprayed toward the connection surface and the mounting surface to remove the attached resin. Further, it may be removed by irradiating laser light toward the connection surface and the mounting surface, or may be removed by applying a chemical.

  The side surface of the mounting terminal 22 may be exposed on the surface of the mold package 26. When the piezoelectric oscillator 10 is mounted on the mounting board via the bonding material, the bonding material that protrudes from the mounting surface of the mounting terminal 22 rises along the side surface of the mounting terminal 22, and the mounting terminal 22 A fillet is formed on the side surface of 22. Thereby, the connection between the electrode pattern of the mounting board and the mounting terminal 22 of the piezoelectric oscillator 10 can be easily confirmed from the appearance.

The moisture resistant material is applied to the surface of the mold package 26 on the side where the piezoelectric vibrating piece 14 is mounted, and the surface of the mold package 26 is coated 52. At this time, in the connection surface of the connection terminal 16, the coating 52 is applied to the peripheral portion of the connection surface, and the coating 52 is not applied to the central portion of the connection surface. By coating 52 in this way, there is no place where moisture passes on the surface of the mold package 26 on the piezoelectric vibrating piece 14 side. The moisture resistant material may be a material having higher moisture resistance than the mold material of the mold package 26. For example, glass is used . If glass is used, the piezoelectric vibrating piece 14 can be completely hermetically sealed.

  The connection surface of the connection terminal 16 and the mounting surface of the mounting terminal 22 are plated to improve the adhesion of the conductive material 54 to the connection surface and the bonding material to the mounting surface. In this plating, for example, nickel plating and gold plating may be performed on the connection surface and the mounting surface, or solder plating may be performed on the connection surface and the mounting surface. In this embodiment, since the coating 52 overlaps with the peripheral edge portion of the connection surface, only the central portion is plated on the connection surface. Therefore, in the present embodiment, since the area to be plated is smaller than that in the case where the entire connection surface is plated, the manufacturing cost can be kept low. This is a particularly remarkable effect when expensive gold is used. As another embodiment, the mold package 26 may be coated with a moisture resistant material 52 after the connection surface and the mounting surface are plated. In this case, unevenness may be provided on the plating surface to improve the adhesion between the plating surface and the material of the coating 52.

  Thereafter, the piezoelectric vibrating piece 14 is electrically and mechanically connected to the connection surface of the connection terminal 16 via the conductive material 54. In FIG. 2, the piezoelectric vibrating piece 14 is mounted in a cantilever shape, but may be mounted in a double-supported shape. The piezoelectric vibrating piece 14 may be a piezoelectric vibrating piece such as an AT cut that generates a thickness shear vibration. A tuning fork type piezoelectric vibrating piece or a surface acoustic wave (SAW) resonance piece can be used instead of the piezoelectric vibrating piece 14. In FIG. 1, the piezoelectric vibrating piece 14 is used. In the piezoelectric vibrating piece, excitation electrodes 58 are formed on both surfaces of a piezoelectric substrate 56 made of a piezoelectric material, and connection electrodes 34 that are electrically connected to the excitation electrodes 58 are formed at corners of the piezoelectric substrate 56. Further, the tuning fork type piezoelectric vibrating piece is formed by projecting a plurality of vibrating arms from a base, forming an excitation electrode on each vibrating arm, and forming a connection electrode connected to the excitation electrode on the base. Furthermore, the SAW resonator element has a comb-like electrode (IDT) formed on the upper surface of the piezoelectric substrate, and a connection electrode connected to the IDT. If the connection electrode of the SAW resonance piece is provided on the lower surface of the piezoelectric substrate and the connection electrode and the IDT are connected via the side surface of the piezoelectric substrate, the surface on which the surface acoustic wave propagates to the SAW resonance piece faces upward. The SAW resonance piece can be mounted on the connection terminal 16. This makes it easy to expose the IDT to plasma, ions, or the like when adjusting the frequency of the piezoelectric vibrating piece 14. The conductive material 54 is made of a resin or metal such as a conductive adhesive or solder.

  After mounting the piezoelectric vibrating piece 14 on the connection terminal 16, the connection portion between the frame portion 32 of each lead frame 18, 24 and each lead is cut. The cutting position is preferably near the surface of the mold package 26, but the adjustment terminal 46 of the IC chip 30 is protruded from the mold package 26 and cut.

  Next, the frequency of the piezoelectric oscillator 10 is adjusted. The frequency adjustment of the piezoelectric oscillator 10 is performed by first cutting the electrode of the piezoelectric vibrating piece 14 or forming a metal film on the electrode. Here, the electrode of the piezoelectric vibrating piece 14 is an excitation electrode, and the frequency is adjusted by cutting the excitation electrode or forming a metal film on the electrode. When a tuning fork type piezoelectric vibrating piece is used instead of the piezoelectric vibrating piece 14, the electrode is a weight provided on the vibrating rod, and the frequency is adjusted by cutting the weight or forming a metal film on the electrode. Is done. Further, when a SAW resonance piece is used instead of the piezoelectric vibrating piece 14, the electrode is an IDT, and the frequency is adjusted by cutting the IDT.

  When the electrode of the piezoelectric vibrating piece 14 is cut, the electrode is irradiated with plasma, ions, laser light, or the like. Specifically, first, the mold package 26 on which the piezoelectric vibrating piece 14 is mounted is placed in a vacuum container, and the piezoelectric vibrating piece 14 is excited. Then, while measuring the oscillation frequency when excited, an etching gas is introduced into the vacuum vessel to generate plasma, and the electrode of the piezoelectric vibrating piece 14 is exposed to this plasma to etch the electrode. Etching is terminated when the desired oscillation frequency is approached. That is, the oscillation frequency is driven to some extent by etching.

  Further, when the electrodes of the piezoelectric vibrating piece 14 are scraped using ions, the piezoelectric vibrating piece 14 is irradiated with ions from an ion gun provided in a vacuum vessel while measuring the oscillation frequency when the piezoelectric vibrating piece 14 is excited. The electrode of the piezoelectric vibrating piece 14 may be etched. Furthermore, when the electrode of the piezoelectric vibrating piece 14 is cut using laser light, the electrode of the piezoelectric vibrating piece 14 is irradiated with laser light while measuring the oscillation frequency when the piezoelectric vibrating piece 14 is excited. You only have to sharpen it. Note that the piezoelectric vibrating piece 14 and the SAW resonance piece are preferably shaved using plasma or ions, and the tuning fork-type piezoelectric vibrating piece 14 is preferably shaved using laser light.

  When adjusting the frequency by forming a metal film on the electrode of the piezoelectric vibrating piece 14, first, a mask is provided on the upper surface of the piezoelectric vibrating piece 14 so that only the electrode is exposed, and the mold package 26 on which the piezoelectric vibrating piece 14 is mounted. Is placed in a deposition apparatus such as vapor deposition. Then, the piezoelectric vibrating piece 14 is excited to measure the oscillation frequency of the piezoelectric vibrating piece 14 and form a metal film on the electrode. The metal film formation ends when the desired oscillation frequency is approached. That is, the oscillation frequency is driven to some extent by metal film formation. The metal material to be formed is preferably the same as the electrode material of the piezoelectric vibrating piece 14 in order to improve adhesion.

  After this frequency adjustment, a lid 28 that hermetically seals the piezoelectric vibrating piece 14 is joined to the mold package 26. Specifically, the lid 28 is a flat substrate made of metal, glass, resin, or the like. Then, the mold package 26 on which the piezoelectric vibrating piece 14 is mounted and the lid are placed in an airtight container, and the airtight container is evacuated or filled with an inert gas such as nitrogen. Thereafter, the lid 28 is joined to the upper surface of the rising portion 60 provided on the periphery of the mold package 26 on the piezoelectric vibrating piece 14 side via the brazing material 61, and the piezoelectric vibrating piece 14 is hermetically sealed. The brazing material 61 may be, for example, low melting point glass or resin. Further, when a resin is used for the lid 28, moisture-resistant coating may be applied to the surface of the lid 28 facing the piezoelectric vibrating piece 14 side. The moisture resistant material used for this coating may be the same as the moisture resistant material coated on the surface of the metal package or the mold package 26.

  Next, the oscillation frequency of the piezoelectric oscillator 10 is adjusted once again. In the previous step of sealing the lid 28, the electrode thickness of the piezoelectric vibrating piece 14 is adjusted to drive the oscillation frequency to a certain extent. Therefore, in this step, the oscillation frequency of the piezoelectric oscillator 10 is adjusted to a desired frequency. . In this adjustment, the frequency is adjusted by bringing the probe into contact with the adjustment terminal 46 exposed to the outside of the mold package 26 and writing to the IC chip 30. FIG. 4 is an explanatory diagram of a circuit that performs frequency adjustment. 4A is an explanatory diagram of a capacitor array, and FIG. 4B is an explanatory diagram of a circuit using variable capacitance diodes. In FIG. 4A, the configuration using three capacitors is described, but the number of capacitors is not limited to three. When the frequency is adjusted using the capacitor array 62 shown in FIG. 4A, the capacitor array 62 is provided in the IC chip 30, and a plurality of capacitors 64 having different capacities are connected in parallel. Each is connected to a switch 66. Then, by writing to the IC chip 30, the switch 66 is turned on / off to adjust the load capacity, and the oscillation frequency of the piezoelectric oscillator 10 is adjusted to a desired frequency. 4B, when the frequency is adjusted by the circuit using the variable capacitance diode 68 shown in FIG. 4B, this circuit is provided in the IC chip 30 and has a capacitance corresponding to the voltage supplied to the variable capacitance diode 68. By adjusting, the oscillation frequency of the piezoelectric oscillator 10 is adjusted to a desired frequency. The adjustment terminal 46 after the frequency adjustment may be cut off near the surface of the mold package 26, or may be bent and commercialized as it is.

  When a tuning fork type piezoelectric vibrating piece is used as the piezoelectric vibrating piece 14 and a glass lid 28 is used, the lid 28 is joined and hermetically sealed with the tuning fork type piezoelectric vibrating piece. The piezoelectric oscillator 10 may be adjusted to a desired oscillation frequency by irradiating the electrode (weight) provided on the vibrating arm via a laser beam. Further, the piezoelectric oscillator 10 is made to oscillate at a desired frequency by irradiating the electrode of the tuning fork type piezoelectric vibrating piece with laser light until just before being adjusted to the desired oscillation frequency of the piezoelectric oscillator 10 and then writing to the IC chip 30. The frequency may be adjusted.

  In some embodiments, the frequency adjustment after the piezoelectric vibrating piece 14 is mounted on the mold package 26 may be adjusted to a desired frequency, and the frequency adjustment after the lid 28 is joined to the mold package 26 may not be performed.

  Thus, the piezoelectric oscillator 10 can reduce the thickness of the ceramic constituting the package base by mounting the piezoelectric vibrating piece 14 on the lead frame via the conductive material 54. The thickness of the piezoelectric oscillator according to the prior art in which the piezoelectric vibrating piece 14 is housed in a package is 1.0 to 1.2 mm, and the thickness of the bottom plate (ceramic) of the package base is 0.15 to 0.2 mm. . Therefore, the thickness of the piezoelectric oscillator 10 according to the present embodiment can be reduced by at least 0.15 to 0.2 mm compared to the piezoelectric oscillator according to the prior art. Since the piezoelectric oscillator 10 is thinned, the distance between the piezoelectric vibrating piece 14 and the IC chip 30 is shortened, so that the temperature difference between the piezoelectric vibrating piece 14 and the IC chip 30 can be reduced. As a result, when the piezoelectric oscillator 10 is of the temperature compensation type, it is possible to accurately correct the frequency change due to the temperature, and to obtain a frequency temperature characteristic with a small frequency deviation.

  The frequency of the piezoelectric oscillator 10 can be adjusted by adjusting the thickness of the electrode provided on the piezoelectric vibrating piece 14 in a state where the piezoelectric vibrating piece 14 is mounted on the mold package 26. The frequency of the piezoelectric oscillator 10 can be adjusted by adjusting the load capacitance on the IC chip 30 side or adjusting the voltage supplied to the variable capacitance diode 68. That is, the frequency adjustment of the piezoelectric oscillator 10 is a two-stage adjustment method in which the load capacitance or voltage is adjusted on the IC chip 30 side after the electrode thickness of the piezoelectric vibrating piece 14 is adjusted. A capacitor 64 having a small capacity can be provided at 62. Therefore, since the oscillation frequency of the piezoelectric oscillator 10 can be finely adjusted, a desired oscillation frequency can be obtained.

  Incidentally, since the size of the IC chip 30 is limited, the number of capacitors 64 of the capacitor array 62 mounted on the IC chip 30 is also limited. For this reason, in the case of a one-stage adjustment method in which the frequency adjustment of the piezoelectric oscillator is performed only on the IC chip side, the capacitor array requires a capacitor for adjusting the frequency greatly and a capacitor for fine adjustment, but the number of capacitors is limited. Therefore, it is not possible to mount all the capacitors required for frequency adjustment in the capacitor array. Therefore, the oscillation frequency of the piezoelectric oscillator cannot be adjusted to a desired frequency. Further, in the case of a one-step adjustment method in which only the electrode thickness of the piezoelectric vibrating piece is adjusted for the frequency adjustment of the piezoelectric oscillator, the oscillation frequency of the piezoelectric oscillator may shift due to the influence of gas generated when the lid is joined. There is. Furthermore, after the lid is joined, the electrodes of the piezoelectric vibrating piece and the SAW resonant piece cannot be exposed to plasma or ions, so the frequency of the piezoelectric oscillator cannot be adjusted. In this respect, since the piezoelectric oscillator 10 according to the present embodiment is a two-stage frequency adjustment method, the oscillation frequency of the piezoelectric oscillator 10 can be accurately adjusted to a desired frequency. In addition, since the number of capacitors 64 of the capacitor array 62 mounted on the IC chip 30 can be reduced, the IC chip 30 can be reduced in size, and the piezoelectric oscillator 10 can also be reduced in size.

  FIG. 5 shows an explanatory diagram of mold sealing of the connection terminal 16. In the embodiment described above, the connection surface of the connection terminal 16 has been described as being exposed on the surface of the mold package 26, but other embodiments can also be used. That is, as shown in FIG. 5A, the connection terminal 16 can be provided in the mold package 26, and the central portion of the connection surface of the connection terminal 16 can be exposed. As shown in FIG. It is also possible to provide leads serving as 16 connection surfaces outside the mold package 26.

  FIG. 6 is an explanatory diagram of a portion where the piezoelectric vibrating piece 14 is supported by the connection terminal 16. In the above-described embodiment, the conductive material 54 has been described using a resin system or a metal system. However, as another embodiment, a metal ball 70 such as a solder can be used. In this case, the recess 72 is provided so that the connection terminal 16 matches the shape of the metal ball 70. Then, after the metal ball 70 is attached to the piezoelectric vibrating piece 14, the piezoelectric vibrating piece 14 is placed on the connection terminal 16 so that the metal ball 70 fits in the recess 72, and the recess 72 is deformed so that the connection terminal 16 is caulked. The piezoelectric vibrating piece 14 may be mounted on the connection terminal 16. In another embodiment, metal bumps may be used as the conductive material 54 and the piezoelectric vibrating piece 14 may be mounted on the connection terminal 16 by flip chip bonding.

  FIG. 7 shows an explanatory view of the support means. When the piezoelectric vibrating piece 14 is mounted in a cantilever manner, the support means 74 can be provided on the side opposite to the side on which the piezoelectric vibrating piece 14 is supported. The support means 74 is a convex portion that supports the piezoelectric vibrating piece 14 provided on the surface of the mold package 26, and deforms the connection terminal 16 that does not contribute to the mounting of the piezoelectric vibrating piece 14 into a convex shape, or the mold package 26. What is necessary is just to form a convex part with this mold material. The connection terminal 16 provided with the supporting means 74 is provided so that the connection surface of the connection terminal 16 is exposed on the surface of the mold package 26 as shown in FIG. As shown in FIG. 7, the connection terminal 16 is provided in the mold package 26, the support means 74 is provided so as to protrude from the mold package 26, and the connection terminal 16 is connected to the mold package 26 as shown in FIG. It may be provided outside. When the support means 74 is formed of a molding material, it is only necessary to provide a recess for forming the support means 74 in the mold. For example, as shown in FIG. As shown in FIG. 7E, the connection terminals 16 may be provided inside the mold package 26, and the support means 74 may be provided above the connection terminals 16. Further, the support means 74 may be formed by forming convex portions by the moisture resistant coating 52. Note that there is no problem even if the connection surface of the connection terminal 16 that does not contribute to the mounting of the piezoelectric vibrating piece 14 is covered with a molding material or a moisture resistant coating 52.

  FIG. 8 is an explanatory diagram of the mounting lead 20. In the above-described embodiment, the mounting surface of the mounting terminal 22 is a flat surface. However, as another embodiment, the concave portion 76 or the convex portion 78 can be provided on the mounting surface. As shown in FIG. 8A, a recess 76 can be provided on the mounting surface, and as shown in FIG. 8B, a protrusion 78 can be provided on the mounting surface. Such a recess 76 or protrusion 78 can be easily formed by pressing the mounting lead 20. When the concave portion 76 is provided on the mounting surface when the piezoelectric oscillator 10 is mounted on the mounting substrate, the contact area between the mounting surface and the bonding material is increased, and the bonding material enters the concave portion 76. The joint strength can be increased. Further, when the convex portion 78 is provided on the mounting surface, the contact area between the mounting surface and the bonding material is increased, and the bonding strength with the mounting substrate can be increased by the anchor effect of the convex portion 78.

  FIG. 9 shows a cross-sectional view of a piezoelectric oscillator according to another embodiment. In the embodiment described above, the rising portion 60 is provided on the periphery of the mold package 26 on the piezoelectric vibrating piece 14 side of the mold package 26. However, as another embodiment, the rising portion 60 is not provided. it can. In this case, the lid 79 may have a bowl shape in which a peripheral edge of a flat substrate made of metal, glass, resin, or the like is raised. Then, the mold package 26 and the lid 79 may be joined with the brazing material 61.

  In the above-described embodiment, both the connection lead 12 and the mounting lead 20 are formed by bending. However, only one of the leads may be bent to form a piezoelectric oscillator. FIG. 10 shows an explanatory diagram of a laminated lead frame in which only one lead is bent. 10A shows a form in which the connecting lead is bent, and FIG. 10B shows a form in which the mounting lead is bent. When only the connection lead 12 is bent as shown in FIG. 10A, the connection lead 12 is formed by bending upward from the upper lead frame, and the mounting lead 20a is in the same plane as the lower lead frame. And is not provided with an inclined portion. The IC chip 30 is mounted on the upper surface of the die pad 48 provided on the lower lead frame, and the IC chip 30 is electrically connected to the connection terminal 16, the mounting terminal 22, and the adjustment terminal via the wire 40. . The bending of the connection lead is formed higher than the maximum height of the wire 40 that electrically connects the IC chip 30 to the connection terminal 16, the mounting terminal 22, and the adjustment terminal. A die pad may be formed on the upper lead frame, and an IC chip may be mounted on the upper surface of the die pad.

Further, as shown in FIG. 10B, when only the mounting lead 20 is bent, the mounting lead 20 is formed to be bent downward from the lower lead frame. The connection lead 12a is composed of a planar connection terminal 16 in the same plane as the upper lead frame, and is not provided with an inclined portion. The IC chip 30 is mounted on the lower surface of the die pad 48 provided on the lower lead frame, and the IC chip 30 is electrically connected to the connection terminal 16, the mounting terminal 22, and the adjustment terminal via the wire 40. . The bending of the mounting lead is formed higher than the maximum height of the wire 40 that electrically connects the IC chip 30 to the connection terminal 16, the mounting terminal 22, and the adjustment terminal. A die pad may be formed on the upper lead frame, and an IC chip may be mounted on the lower surface of the die pad.
In this way, by forming either the connecting lead 12 or the mounting lead 20 by bending, the vertical dimension of the laminated lead frame can be reduced, and the piezoelectric oscillator can be made thinner.

  In the above-described embodiment, at least one of the connecting lead 12 and the mounting lead 20 is formed by being bent, but may be formed by using half etching. That is, the upper lead frame and the lower lead frame may be formed thick, and the connecting lead 12 and the mounting lead 20 may be formed by changing the thickness of these lead frames by etching. Further, the connecting lead 12 or the mounting lead 20 may be formed by rolling the upper lead frame or the lower lead frame to change the thickness of the lead.

  Next, an example in which the above-described piezoelectric oscillator is mounted on an electronic device will be described. FIG. 11 shows a schematic configuration diagram of a digital mobile phone. The digital cellular phone 80 includes a transmission / reception signal transmission unit 82 and a reception unit 84, and a central processing unit (CPU) 86 for controlling them is connected to the transmission unit 82 and the reception unit 84. In addition to modulation and demodulation of transmission / reception signals, the CPU 86 controls an information input / output unit 88 including a display unit and operation keys for inputting information, and a memory 90 including a RAM and a ROM. For this reason, a piezoelectric device 92 is attached to the CPU 86, and its output frequency is used as a clock signal suitable for the control contents by a predetermined frequency dividing circuit (not shown) incorporated in the CPU 86. The CPU 86 is connected to a temperature compensated piezoelectric oscillator 94, and the temperature compensated piezoelectric oscillator 94 is connected to the transmitter 82 and the receiver 84. Thus, even if the basic clock from the CPU 86 fluctuates when the environmental temperature changes, it is corrected by the temperature compensated piezoelectric oscillator 94 and supplied to the transmitter 82 and the receiver 84.

  As an example to which the piezoelectric oscillator according to the embodiment of the present invention is applied, there is a temperature compensated piezoelectric oscillator (TCXO), for example. The TCXO is a piezoelectric oscillator in which frequency fluctuation due to ambient temperature change is reduced, and is widely used as a frequency reference source for the receiving unit 84 and the transmitting unit 82. This TCXO has been increasingly demanded for downsizing of the cellular phone 80 device in recent years, and downsizing of the piezoelectric oscillator according to the embodiment of the present invention is extremely useful. The piezoelectric oscillator according to the embodiment of the present invention can also be applied to a real-time clock that supplies date / time information to a mobile phone 80 device including a CPU 86, for example.

  The piezoelectric oscillator according to the embodiment of the present invention is not limited to the above-described digital mobile phone device, and is controlled by a piezoelectric oscillator such as a personal computer, a workstation, a PDA (Personal Digital [Data] Assistant). The present invention can be applied to an electronic device that obtains a clock signal. As described above, by using the piezoelectric oscillator according to the above-described embodiment for an electronic device, a smaller and more reliable electronic device can be realized.

It is the perspective view which decomposed | disassembled the piezoelectric oscillator which concerns on this Embodiment. It is sectional drawing in the AA of FIG. It is a top view of a lead frame. It is explanatory drawing of the circuit which performs frequency adjustment. It is explanatory drawing of the mold sealing of a connection electrode. It is explanatory drawing of the location where a piezoelectric vibrating piece is supported by a connection electrode. It is explanatory drawing of a support means. It is explanatory drawing of the lead for mounting. It is sectional drawing of the piezoelectric oscillator which concerns on other embodiment. It is explanatory drawing of the lamination | stacking lead frame which bent only one lead. It is a schematic block diagram of a digital mobile phone. It is sectional drawing of the piezoelectric oscillator which concerns on a prior art.

Explanation of symbols

10... Piezoelectric oscillator 14... Piezoelectric vibrating piece 16... Connection terminal 18... Upper lead frame 22. Mold package, 28... Lid, 30... IC chip, 48... Die pad, 80.

Claims (12)

A laminated lead frame having a connection lead having a connection terminal formed by bending on one side and a mounting lead having a mounting terminal formed by bending on the other side and bonded to a mounting substrate. Forming, and
Mounting electronic components on the multilayer lead frame, electrically connecting the multilayer lead frame and the electronic components;
Exposing the surfaces of the connection terminals and the mounting terminals and mold-sealing the laminated lead frame and the electronic component;
Mounting the piezoelectric vibrating piece on the connection terminal via a conductive material;
Covering the piezoelectric vibrating piece with a lid and hermetically sealing;
A method for manufacturing a piezoelectric oscillator, comprising:   The method for manufacturing a piezoelectric oscillator according to claim 1, wherein the mold sealing step includes a step of applying a moisture-resistant material to a surface of the molding material where the connection terminals are exposed.   The method of manufacturing a piezoelectric oscillator according to claim 1, wherein the step of mounting the piezoelectric vibrating piece includes a step of adjusting an oscillation frequency of the piezoelectric vibrating piece. A piezoelectric vibrating piece;
A lead frame formed with a connection terminal having a connection surface on which the piezoelectric vibrating piece is mounted;
A mold package that seals the lead frame while exposing at least the connection surface;
A lid that covers the piezoelectric vibrating piece and is airtightly bonded to the mold package;
Have
The lead frame is a laminated lead frame of at least two sheets,
And a lead for connection is formed on one of the lead frames, a lead for mounting is formed on the other lead frame,
At least one of the connecting lead and the mounting lead is bent to the opposite side of the laminated surface;
A piezoelectric oscillator characterized by that . The lead frame is formed with mounting terminals,
The piezoelectric oscillator according to claim 4, wherein a mounting surface of the mounting terminal is exposed from the mold package. A piezoelectric oscillator having a plurality of leads formed from a lead frame, wherein the terminals formed on the plurality of leads and spaced apart from each other are arranged in a plurality of stages in the vertical direction of the package, and at least a piezoelectric vibrating piece as the terminal Having mounted connection terminals ,
The lead frame is a laminated lead frame of at least two sheets,
And a lead for connection is formed on one of the lead frames, a lead for mounting is formed on the other lead frame,
One of the connecting lead and the mounting lead is bent to the side opposite to the laminated surface . An upper lead frame that raises the connection lead to one side and serves as a connection terminal to the piezoelectric vibrating piece, and a lower lead frame that serves as a mounting terminal to the mounting board by raising the mounting lead to the other side A laminated lead frame, and
Electronic components mounted on the laminated lead frame;
A mold package that seals the laminated lead frame and the electronic component while exposing the connection surface of the connection terminal and the mounting surface of the mounting terminal;
A piezoelectric vibrating piece mounted on the connection surface of the connection terminal;
A lid that covers the piezoelectric vibrating piece and is airtightly bonded to the mold package;
A piezoelectric oscillator comprising: 8. The piezoelectric oscillator according to claim 4, wherein the mold package is formed by applying a moisture-proof material to a surface where the connection terminal is exposed. On the side of the mold package on which the connection terminal is provided, a protrusion projecting toward the piezoelectric vibrating piece is formed by a connection terminal that is not used for mounting the molding material or the piezoelectric vibrating piece of the mold package. The piezoelectric oscillator according to claim 4, wherein the portion is used as a supporting means for the piezoelectric vibrating piece. The piezoelectric oscillator according to any one of claims 4 to 9 , wherein the connection terminal has a recess formed in an exposed connection surface.   8. The piezoelectric oscillator according to claim 5, wherein the mounting terminal has a concave portion or a convex portion formed on the exposed mounting surface. 9. An electronic apparatus comprising the piezoelectric oscillator according to claim 4 .

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