Piezoelectric vibration device and method for manufacturing the same

Abstract

This invention facilitates the adjustment of the F0 (original frequency) of the completed piezoelectric vibration device, thereby providing a piezoelectric vibration device with excellent operational reliability. [Solution] First and second metal films 8 and 9 are formed on the upper surface 2a and lower surface 2b of the substrate 2, respectively. The device is designed so that the original frequency of the piezoelectric vibration device 1 is slightly lower than the target frequency. When the resonant frequency of the piezoelectric vibration device 1 deviates from the target frequency after mounting on the substrate 2, there is a frequency deviation. One of the connecting parts 9b that connects the multiple main parts 9a of the second metal film 9 forming the capacitance part C is cut off together with the base film 7 to divide the second metal film 9. The area of ​​the second electrode film 9 connected to the input side of the piezoelectric vibrator 3 is reduced to decrease the capacitance of the capacitance part C, and the original frequency of the piezoelectric vibration device 1 is adjusted to match the target frequency.

Description

Technical Field

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[0001] The present invention relates to a piezoelectric vibration device including an insulating substrate, a piezoelectric vibrator mounted on one main surface of the insulating substrate, and an integrated circuit element, and a method for manufacturing the same.

Background Art

[0002] As a piezoelectric vibration device, for example, there is a piezoelectric vibration device disclosed in Patent Document 1. This piezoelectric vibration device includes a substrate, a piezoelectric vibrator and an electronic component mounted on one main surface of the substrate, a mounting terminal portion formed on the other main surface of the substrate, and a mold resin layer that molds the piezoelectric vibrator and the electronic component on one main surface side of the substrate so as to cover them.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in the case of the above-described conventional piezoelectric vibration device, an integrated circuit element for an oscillator having an oscillation amplification circuit is mounted as an electronic component. Usually, such an integrated circuit element for an oscillator does not have a so-called F0 (resonance frequency) adjustment function. Therefore, when a frequency deviation occurs with respect to the target frequency of the resonance frequency of oscillation when the piezoelectric vibration device is mounted on a substrate, it is difficult to easily adjust the frequency deviation. In particular, adjusting the frequency deviation becomes even more difficult by molding with a sealing resin, resulting in a problem of a decrease in operational reliability.

[0005] The present invention has been made in view of the above problems, and an object thereof is to provide a piezoelectric vibration device that can easily perform F0 adjustment of the completed piezoelectric vibration device and has excellent operational reliability.

Means for Solving the Problems

[0006] To achieve the above objective, the piezoelectric vibration device according to the present invention comprises a substrate, a piezoelectric vibrator and an integrated circuit element mounted on the substrate, wherein the piezoelectric vibrator comprises a piezoelectric vibration element having a pair of excitation electrodes and a sealing member that seals the piezoelectric vibration element, the integrated circuit element comprises an oscillation amplification circuit to which the input terminal and output terminal are connected to the input side and output side of the pair of excitation electrodes of the piezoelectric vibration element, respectively, the substrate comprises at least one insulating substrate, the insulating substrate is mounted on the piezoelectric vibrator and the integrated circuit element The substrate comprises one main surface on which a component is mounted, the other main surface on which an external connection terminal is provided, a first metal film connected to the input and / or output side of the piezoelectric vibrator, a second metal film formed in a position not overlapping the external connection terminal and grounded, and constituting a capacitance together with the first metal film, and an insulating base film covering the surface of each of the two main surfaces of the substrate, including the first and second metal films, except for a portion of each of the two main surfaces of the substrate, wherein the second metal film is formed to be separable by being cut together with the base film at least at one location.

[0007] In this case, the first metal film may be formed on one main surface of the substrate, and the second metal film may be formed on the other main surface of the insulating substrate at a position opposite to the first metal film.

[0008] In this configuration, a capacitance section is formed by a first metal film and a second metal film. The first metal film is connected to the input and / or output side of the piezoelectric vibrator, and the grounded second metal film is formed to be separable by being cut together with the substrate film at at least one location. Therefore, the device is designed so that the resonant frequency of the piezoelectric vibration device is slightly lower than the target frequency. When the measured frequency of the piezoelectric vibration device after mounting on the substrate deviates from the target frequency, resulting in a frequency deviation, the second metal film forming the capacitance section can be cut and separated together with the substrate film at one location. This allows the area of ​​the second electrode film connected to the input and / or output side of the piezoelectric vibrator to be reduced, thereby decreasing the capacitance of the capacitance section. This reduction in capacitance raises the resonant frequency of the piezoelectric vibration device, allowing it to match the target frequency. Note that if there is no frequency deviation, it is not necessary to separate the second metal film.

[0009] Furthermore, after mounting the piezoelectric vibration device onto the substrate, the second metal film on the other main surface side of the substrate can be easily adjusted to the target frequency by cutting it at a predetermined location. This suppresses variations in the resonant frequency of each piezoelectric vibration device relative to the target frequency, thereby improving yield.

[0010] In this case, the second metal film can be cut from the outside without touching the inside of the piezoelectric vibration device or interfering with the external connection terminals on the other main surface of the substrate, making it easy to adjust the frequency by cutting. Moreover, since the cutting point of the second metal film where the capacitance of the capacitive section becomes the optimal value can be appropriately selected, it becomes possible to fine-tune the frequency deviation of the resonant frequency of the piezoelectric vibration device from the target frequency to zero.

[0011] Furthermore, when the second metal film is divided, the substrate film at the divided portion is also removed simultaneously, and the area outside the divided portion remains covered with an insulating substrate film. Therefore, when connecting the external connection terminal of the piezoelectric vibration device to an external circuit, the risk of a short circuit between the second metal film forming the capacitance portion and the external connection terminal can be prevented, thereby improving reliability.

[0012] Furthermore, the capacitance unit is preferably connected in series with the excitation electrode of the piezoelectric vibrator that is connected to the input terminal of the oscillation amplification circuit.

[0013] With this configuration, by connecting the capacitive section in series with the excitation electrode connected to the input terminal of the oscillation amplifier circuit, the capacitive section is connected to the preceding stage of the oscillation amplifier circuit of the integrated circuit element. Compared to connecting it to the excitation electrode on the output terminal side of the oscillation amplifier circuit, the original frequency of the piezoelectric vibration device can be adjusted more precisely by adjusting the capacitance of the capacitive section, allowing for more accurate adjustment of the original frequency of the piezoelectric vibration device and broadening the range of frequency adjustment.

[0014] Furthermore, the second metal film may comprise a plurality of main portions formed at predetermined intervals and a plurality of connecting portions connecting the main portions, and the second metal film may be divided by cutting off any of the connecting portions and the base film covering the connecting portions.

[0015] With this configuration, the capacity of the volume section can be easily varied by dividing the second metal film by removing any of the multiple connecting parts that constitute the second metal film together with the base film.

[0016] Furthermore, the multiple main parts may have substantially the same shape, and at least one of the multiple main parts may have a different shape from the others.

[0017] This configuration allows for the selection of combinations of areas of the second metal film after division according to the frequency deviation, enabling highly accurate adjustment of the frequency deviation.

[0018] Furthermore, the substrate film of the insulating substrate may be translucent. With this configuration, when dividing the second metal film, the dividing position can be clearly recognized from the outside, and the dividing work can be carried out smoothly.

[0019] Furthermore, it is preferable to further include a mold resin layer that covers the piezoelectric vibrator and the integrated circuit element mounted on the substrate.

[0020] According to this configuration, the mold resin layer can protect the piezoelectric vibrator and the integrated circuit element mounted on the substrate. On the other hand, even if the piezoelectric vibrator and the integrated circuit element mounted on the substrate are molded with resin, it is possible to easily adjust the F0 of the piezoelectric vibration device by dividing the second metal film.

[0021] Moreover, the manufacturing method of the piezoelectric vibration device according to the present invention includes a preparation step of preparing the piezoelectric vibration device, a measurement step of measuring the resonance frequency of the prepared piezoelectric vibration device by a measuring means, a derivation step of deriving a frequency deviation between the measured frequency in the measurement step and a preset target frequency by a derivation means, and an adjustment step of setting a division position of the second metal film at which the frequency deviation derived in the derivation step becomes substantially zero, and dividing the second metal film at the division position to variably adjust the capacitance of the capacitance portion. It is desirable to include these steps.

[0022] According to this configuration, a piezoelectric vibration device in which a piezoelectric vibrator and an integrated circuit element are mounted on a substrate is prepared, the resonance frequency of the prepared piezoelectric vibration device is measured to derive a frequency deviation from the target frequency, and the division position of the second metal film at which the derived frequency deviation becomes substantially zero is determined and divided, whereby the frequency deviation can be made substantially zero, and the F0 adjustment of the completed piezoelectric vibration device can be easily performed.

Effects of the Invention

[0023] According to the present invention, it becomes possible to easily adjust the F0 of the completed piezoelectric vibration device, and a piezoelectric vibration device with excellent operational reliability can be provided.

Brief Description of the Drawings

[0024] [Figure 1] It is a cross-sectional view taken along the line L1-L1 of the piezoelectric vibration device according to the first embodiment of the present invention. [Figure 2] Cross-sectional view taken along the L2-L2 line of the piezoelectric vibration device according to the first embodiment. [Figure 3] Plan view of the piezoelectric vibration device of FIG. 1 in a state where the mold resin is removed. [Figure 4] Plan view of the insulating substrate in a state where the mold resin, piezoelectric vibrator, and integrated circuit element of the piezoelectric vibration device of FIG. 1 are removed. [Figure 5] Bottom view of the insulating substrate of the piezoelectric vibration device of FIG. 1. [Figure 6] Circuit connection diagram of the piezoelectric vibrator device of FIG. 1 [Figure 7] Cross-sectional view taken along the L1-L1 line for explaining the F0 adjustment operation of the piezoelectric vibration device of FIG. 1. [Figure 8] Bottom view of the insulating substrate for explaining the F0 adjustment operation of the piezoelectric vibration device of FIG. 1. [Figure 9] Bottom view of the insulating substrate in Modification 1 of the piezoelectric vibration device according to the first embodiment. [Figure 10] Bottom view of the insulating substrate in Modification 2 of the piezoelectric vibration device according to the first embodiment. [Figure 11] Bottom view of the insulating substrate in Modification 3 of the piezoelectric vibration device according to the first embodiment. [Figure 12] Cross-sectional view taken along the L1-L1 line of Modification 4 of the piezoelectric vibration device according to the first embodiment. [Figure 13] Circuit connection diagram of the piezoelectric vibration device according to the second embodiment of the present invention. [Figure 14] Plan view of the piezoelectric vibration device according to the third embodiment of the present invention in a state where the mold resin is removed. [Figure 15] Bottom view of the insulating substrate in the piezoelectric vibration device of FIG. 14. [Figure 16] Circuit connection diagram of the piezoelectric vibration device of FIG. 14.

Embodiments for Carrying Out the Invention

[0025] <First Embodiment> A piezoelectric vibration device according to the first embodiment of the present invention will be described with reference to Figures 1 to 8. Note that the A1-A2 axis and B1-B2 axis in Figures 3 to 5 represent the same coordinate axis.

[0026] (composition) As shown in Figure 1, the piezoelectric vibration device 1 comprises a substrate (corresponding to the "substrate" of the present invention) 2, a piezoelectric vibrator (corresponding to the "piezoelectric vibrator" of the present invention) 3 and an IC chip (corresponding to the "integrated circuit element" of the present invention) 4 mounted on the upper surface 2a of the substrate 2, and a resin layer (corresponding to the "molded resin layer" of the present invention) 5 molded on the upper surface 2a side of the substrate 2 so as to cover the piezoelectric vibrator 3 and the IC chip 4. Here, the substrate 2 is made of a single insulating substrate in which a metal foil pattern is formed on a glass epoxy substrate, and the metal foil pattern will be described in detail later. It is preferable that the molded resin layer 5 be formed of a thermosetting resin such as epoxy resin.

[0027] As shown in Figure 1, the piezoelectric vibrator 3 comprises a piezoelectric diaphragm 31, each having a substantially rectangular shape, a first sealing member 32, and a second sealing member 33. In the piezoelectric vibrator 3, the piezoelectric diaphragm 31 and the first sealing member 32 are joined together, and the piezoelectric diaphragm 31 and the second sealing member 33 are joined together to form a substantially rectangular parallelepiped sandwich structure package. That is, in the piezoelectric vibrator 3, the first sealing member 32 and the second sealing member 33 are joined to each of the two main surfaces of the piezoelectric diaphragm 31, forming an internal space S of the package shown by the dashed rectangle in Figure 3, and the piezoelectric vibrating portion (not shown) of the piezoelectric diaphragm 31 is sealed in an airtight state within this internal space. The piezoelectric vibrator 3 and the IC chip 4 are then mechanically joined to the upper surface 2a of the substrate 2 by an insulating bonding material 6, such as epoxy resin.

[0028] The piezoelectric vibrator 3 consists of a piezoelectric diaphragm 31, which is made of an AT-cut quartz plate formed from a single quartz plate and has a roughly rectangular parallelepiped shape that performs thickness-sliding vibration. It has a roughly rectangular vibrating section in which a first excitation electrode and a second excitation electrode are formed at opposing positions on the upper and lower main surfaces. The vibrating section of the piezoelectric diaphragm 31 is surrounded by a thick outer frame with a gap created by a cutout, and the vibrating section and the outer frame are connected by a connecting section.

[0029] The first sealing member 32, like the piezoelectric diaphragm 31, has a substantially rectangular parallelepiped shape formed from a single quartz plate, and the side that is joined to the piezoelectric diaphragm 31 is formed as a flat, smooth surface (mirror finish), and an AT-cut quartz plate is used. The second sealing member 33, like the first sealing member 32, has a substantially rectangular parallelepiped shape formed from a single quartz plate, and the side that is joined to the piezoelectric diaphragm 31 is formed as a flat, smooth surface (mirror finish), and an AT-cut quartz plate is used.

[0030] As shown in Figures 1 and 2, the piezoelectric diaphragm 31 and the first sealing member 32 are stacked on top of each other, and the piezoelectric diaphragm 31 and the second sealing member 33 are also stacked on top of each other and diffusion-bonded to form the first and second seal paths 34a and 34b. The first and second seal paths 34a and 34b are formed in annular shape in plan view, and an internal space S is formed in which the vibrating portion of the piezoelectric diaphragm 31, including the first and second excitation electrodes, is hermetically sealed. This produces the sandwich-structure package shown in Figures 1 and 2.

[0031] As shown in Figure 3, L-shaped first to fourth external connection electrodes 32a, 32b, 32c, and 32d are formed in a counterclockwise direction in plan view at the four corners of the upper surface of the piezoelectric vibrator 3, i.e., the upper surface of the first sealing member 32. These external connection electrodes are, for example, the first external connection electrode 32a which is the output terminal of the piezoelectric vibrator 3, the third external connection electrode 32c which is the input terminal of the piezoelectric vibrator 3, and the second external connection electrode 32b and the fourth external connection electrode 32d which are the ground terminals.

[0032] Furthermore, an insulating base material film 7 is applied to the upper surface (corresponding to "one main surface" of the present invention) 2a and the lower surface (corresponding to "the other main surface" of the present invention) 2b of the substrate 2. At the four corners of the upper surface 2a of the substrate 2, the base material film 7 is peeled off and the surface of the substrate 2 is cut out in a rectangular concave shape to form recesses 21a, 21b, 21c, and 21d. Furthermore, at the four corners of the lower surface 2b of the substrate 2, the base material film 7 is peeled off and the surface of the substrate 2 is cut out in a rectangular concave shape to form recesses 22a, 22b, 22c, and 22d. Here, for example, a highly transparent epoxy resin is used as the base material film 7. Note that the base material film 7 may also be semi-transparent, and it is sufficient that the inside of the base material film 7 on the lower surface 2b side can be seen from the outside.

[0033] Pads 23a and 23b for mounting the first and second piezoelectric vibrators are formed in recesses 21a and 21b on the A2 side of the upper surface 2a of the substrate 2, respectively. The first external connection electrode 32a, which is the output terminal of the piezoelectric vibrator 3 on the upper surface of the first sealing member 32, and the pad 23a for mounting the first piezoelectric vibrator are electrically connected by a wire W, and the third external connection electrode 32c, which is the input terminal of the piezoelectric vibrator 3 on the upper surface of the first sealing member 32, and the pad 23b for mounting the second piezoelectric vibrator are electrically connected by a wire W.

[0034] Pads 24a to 24c for mounting the first to third ICs are formed in the recess 21d on the A1-B1 side of the upper surface 2a of the substrate 2, and pads 24d to 24f for mounting the fourth to sixth ICs are formed in the recess 21c on the A1-B2 side. These pads 24a to 24f for mounting the first to sixth ICs are, for example, the following terminals. Pad 24a for mounting the first IC is the oscillation input terminal on the input side of the excitation electrode, and the first external connection terminal 4a of the IC chip 4 is electrically connected by wire W. Pad 24b for mounting the second IC is the output enable terminal, and the second external connection terminal 4b of the IC chip 4 is electrically connected by wire W. Pad 24c for mounting the third IC is the power terminal, and the third external connection terminal 4c of the IC chip 4 is electrically connected by wire W. Pad 24d for mounting the fourth IC is the oscillation output terminal on the output side of the excitation electrode, and the fourth external connection terminal 4d of the IC chip 4 is electrically connected by wire W. The fifth IC mounting pad 24e is an output terminal, and the fifth external connection terminal 4e of the IC chip 4 is electrically connected by wire W. The sixth IC mounting pad 24f is a ground terminal, and the sixth external connection terminal 4f of the IC chip 4 is electrically connected by wire W.

[0035] Rectangular first to fourth external connection terminals 25a, 25b, 25c, and 25d are formed in the recesses 22a to 22d at the four corners of the lower surface 2b of the substrate 2. These first to fourth external connection terminals are used when mounting the piezoelectric vibration device 1 on other equipment (such as a wiring board), and are, for example, the following terminals: The first external connection terminal 25a is a power terminal, the third external connection terminal 25c and the fourth external connection terminal 25d are the first and second output terminals, and the second external connection terminal 25b is a ground terminal. These external connection terminals 25a to 25d of the substrate 2, each pad 23a, 23b, 24a to 24f, and the external connection electrodes 32a to 32d of the first sealing member 32 of the piezoelectric vibrator 3 are formed by copper plating on copper foil, nickel plating on top of that, palladium plating on top of that, and gold plating on the topmost layer.

[0036] A feature of the present invention is that, as shown in Figure 4, a rectangular first metal film 8 is formed in the center of the upper surface 2a of the substrate 2, and is connected to the second piezoelectric vibrator mounting pad 23b, and then to the input side (input side of the excitation electrode) of the piezoelectric vibrator 3 via wire W and third external connection electrode 32c. Also, as shown in Figure 5, a second metal film 9 is formed in the center of the lower surface 2b of the substrate 2, opposite the first metal film 8 and not overlapping with the first to fourth external connection terminals 25a to 25d. The first and second metal films 8 and 9 are formed on the upper surface 2a, lower surface 2b of the substrate 2 and the upper surface of the first sealing member 32 by copper plating or the like on copper foil. Here, both the first and second metal films 8 and 9 are covered with a base film 7.

[0037] As shown in Figure 5, the second metal film 9 is composed of 10 main parts 9a of the same shape, which are elongated rectangles in the B1-B2 direction, and 9 connecting parts 9b that connect the central parts of adjacent main parts 9a arranged in the A1-A2 direction. The main part 9a on the A2 side is connected to the second external connection terminal (ground terminal) 25b and is covered with the base film 7. Each connecting part 9b is formed such that its length in the A1-A2 direction is smaller than the dimension (width) of each main part 9a in the A1-A2 direction. At this time, the dimensions of the second metal film 9 are formed such that the dimensions in the A1-A2 direction and the B1-B2 direction of the entire 10 main parts 9a connected by the connecting parts 9b are the same as those of the first metal film 8.

[0038] A capacitance section C is formed when the first metal film 8 and the second metal film 9 are positioned opposite each other with a gap in the thickness direction of the substrate 2. By cutting off one of the connecting portions 9b of the second metal film 9 together with the substrate film 7, the electrode area of ​​the second metal film 9 constituting the capacitance section C is made variable, so that a variable capacitance type capacitance section C is connected to the input side (input side of the excitation electrode) of the piezoelectric vibrator 3.

[0039] The piezoelectric vibration device 1, in which a piezoelectric vibrator 3 and an IC chip 4 are mounted on a substrate 2 and a capacitive section C is connected to the input side of the piezoelectric vibrator 3, is shown in Figure 6. In Figure 6, C1 and C2 are load capacitors provided between the input and output sides of the piezoelectric vibrator 3 and ground, respectively; AMP1 is an inverter amplifier connected in parallel to the series circuit of the limiting resistor RD and the piezoelectric vibrator 3; AMP2 is an inverter amplifier connected in series to amplifier AMP1; RF is a feedback resistor connected in parallel to amplifier AMP1; and OUT is the output terminal of amplifier AMP2. A variable capacitance section C is provided in parallel to the load capacitor C1 between the input side of the piezoelectric vibrator 3 and ground. Here, excluding the piezoelectric vibrator 3, the oscillation amplification circuit including inverter amplifiers AMP1 and AMP2, resistors RD and RF, and load capacitors C1 and C2 is made up of IC chip 4.

[0040] (F0 adjustment operation) The F0 adjustment operation of the piezoelectric vibration device 1 will now be described. The manufacturing method of the piezoelectric vibration device of the present invention includes the process up to the completion of the F0 adjustment of the piezoelectric vibration device, and the piezoelectric vibration device 1 is manufactured through the process up to the F0 adjustment described below.

[0041] First, a piezoelectric vibration device 1 having the above-described configuration is prepared (preparation step), the resonant frequency of the prepared piezoelectric vibration device 1 is measured using a frequency measuring instrument (corresponding to the "measuring means" in this invention) (measurement step), and the frequency deviation ΔF between the frequency measured by the frequency measuring instrument and a preset target frequency is derived using, for example, a microcomputer (corresponding to the "derivation means" in this invention / hereinafter simply referred to as a microcomputer) (derivation step). Then, a division position of the second metal film 9 where the derived frequency deviation ΔF becomes approximately zero is selected from among the connecting portions 9b, the selected connecting portion 9b is cut together with the base film 7 to divide the second metal film 9, and the capacitance of the capacitance portion C is adjusted by varying the area of ​​the second metal film 9 as an electrode that forms the capacitance portion C (adjustment step).

[0042] The examples of each of the above processes will be explained in detail. For example, the target frequency Ft of the piezoelectric vibration device 1's F0 (resonant frequency) is pre-stored in the microcontroller's memory, and the frequency deviation ΔF(Ft-Fd) between the measured frequency Fd measured by a frequency measuring instrument and the target frequency Ft of the piezoelectric vibration device 1 read from memory is derived. At this time, since the piezoelectric vibration device 1 is designed so that F0 is slightly lower than the target frequency, the target frequency Ft is higher than the measured frequency Fd, and the frequency deviation ΔF becomes a positive value. By reducing the capacitance of the capacitance section C, the resonant frequency of the piezoelectric vibration device 1 increases, and the frequency deviation ΔF approaches zero.

[0043] Furthermore, the electrode area formed by the 10 main parts 9a of the second metal film 9 changes by 1 / 10 depending on the position of each connecting part 9b that is removed. Specifically, if the first connecting part 9b from the A2 side is removed, the electrode area formed by the main part 9a of the second metal film 9 becomes very small, about 1 / 10 of what it was before removal, and the capacitance of the capacitance part C after removal becomes the smallest value. Similarly, if the ninth connecting part 9b from the A2 side is removed, the electrode area formed by the main part 9a of the second metal film 9 becomes about 9 / 10 of what it was before removal, and the capacitance of the capacitance part C after removal becomes the second largest value after the case where no connecting part 9b is removed.

[0044] For example, measure the volume of the volume section C after the first connecting section 9b from the A2 side in Figure 5 is removed, measure the volume of the volume section C after the second connecting section 9b is removed, and repeat the same measurement until the ninth connecting section 9b is removed, thereby verifying in advance the relationship between the removal position (which number) of the connecting section 9b and the volume of the volume section C after the change.

[0045] Furthermore, since the resonant frequency of the piezoelectric vibration device 1 can be calculated by computation as the capacitance of the capacitance section C connected to the input side of the piezoelectric vibrator 3 changes, the relationship between the change in capacitance of the capacitance section C and the change in the resonant frequency of the piezoelectric vibration device 1 is verified in advance, and the results of the verification are mapped as adjustment parameters and stored in the microcontroller's memory. From the adjustment parameter map stored in memory, the capacitance of the capacitance section C required to make the derived frequency deviation ΔF zero is derived, and one optimal connecting section 9b to be cut off in order to obtain the derived capacitance is selected. The selected connecting section 9b is cut off together with the base film 7 to vary the area of ​​the second metal film 9 as an electrode, and the original frequency of the piezoelectric vibration device 1 is adjusted by adjusting the capacitance of the capacitance section C.

[0046] As a specific example, as shown in Figures 7 and 8, if the frequency deviation between the measured frequency and the target frequency obtained by the frequency measuring instrument is found to be located at the fifth connecting portion 9b from the A2 side, which is in the center of the second metal film 9, then the central connecting portion 9b (fifth from the A2 side) of the second metal film 9 is cut along with the base film 7 so that the lower surface 2b of the substrate 2 is visible from the cut portion E, thereby dividing the area of ​​the electrode made by the second metal film 9 to half of what it was before the cut, and adjusting the capacitance of the capacitance portion C to be smaller.

[0047] By reducing the capacitance of the capacitance section C in this way, as shown in Figure 8, the capacitance of the capacitance section C, which is provided in parallel with the load capacitor C1 on the input side (input side of the excitation electrode) of the piezoelectric vibrator 3, can be reduced and varied. This increases the resonant frequency of the piezoelectric vibration device 1, allowing F0 to be adjusted so that the resonant frequency of the piezoelectric vibration device 1 approximately matches the target frequency.

[0048] Therefore, the piezoelectric vibration device 1 is designed so that its resonant frequency is slightly lower than the target frequency. When the resonant frequency of the piezoelectric vibration device 1 deviates from the target frequency after mounting on the substrate 2, one of the nine connecting portions 9b of the second metal film 9 that forms the capacitance portion C is cut off together with the substrate film 7, thereby dividing the second metal film 9. This reduces the area of ​​the second metal film 9 connected to the input side of the piezoelectric vibrator 3, thereby decreasing the capacitance of the capacitance portion C. This reduction in capacitance increases the resonant frequency of the piezoelectric vibration device 1, and the device is adjusted so that the resonant frequency of the piezoelectric vibration device 1 matches the target frequency.

[0049] As described above, according to the first embodiment, after mounting the piezoelectric vibration device 1 onto the substrate 2, the second metal film 9 of the substrate 2 can be divided at a predetermined location, thereby easily adjusting the resonant frequency of the completed piezoelectric vibration device 1 to the target frequency. As a result, by performing such adjustment, it becomes possible to suppress the variation in the resonant frequency of each piezoelectric vibration device 1 relative to the target frequency during mass production of the piezoelectric vibration device 1 to almost zero, thereby improving the yield.

[0050] Furthermore, since the second metal film 9 can be cut from the outside without touching the inside of the piezoelectric vibration device 1 and without interfering with the external connection terminals 25a to 25d on the lower surface 2b of the substrate 2, the adjustment of the resonant frequency by cutting can be easily performed. Moreover, since the cutting point of the second metal film 9 where the capacitance of the capacitance section C becomes the optimal value can be appropriately selected, it becomes possible to finely adjust the frequency deviation between the resonant frequency of the piezoelectric vibration device 1 and the target frequency to zero.

[0051] Furthermore, when the second metal film 9 is divided, the base film 7 at the divided portion is also removed at the same time, and the area other than the removed divided portion remains covered by the insulating base film 7. Therefore, when connecting the external connection terminals 25a to 25d of the piezoelectric vibration device 1 to an external circuit, the risk of a short circuit between the second metal film 9 forming the capacitive portion C and the external connection terminals 25a to 25d can be prevented, thereby improving reliability.

[0052] Furthermore, by connecting the capacitance unit C in series to the input side of the piezoelectric vibrator 3, which is the input side of the excitation electrode connected to the input terminal of the oscillation amplifier circuit of the IC chip 4, the capacitance unit C is connected to the preceding stage of the oscillation amplifier circuit of the IC chip 4. Compared to connecting it to the excitation electrode on the output terminal side of the oscillation amplifier circuit of the IC chip 4, it becomes possible to adjust the original frequency of the piezoelectric vibration device 1 more precisely by adjusting the capacitance of the capacitance unit C, thereby enabling accurate adjustment of the resonant frequency of the piezoelectric vibration device and broadening the range of frequency adjustment.

[0053] Furthermore, since the upper surface 2a and lower surface 2b of the substrate 2 are covered with a translucent substrate film 7, the position to be cut can be clearly recognized from the outside when cutting the second metal film 9, allowing the cutting work to be carried out smoothly.

[0054] Furthermore, the molded resin layer 5 protects the piezoelectric vibrator 3 and IC chip 4 mounted on the substrate 2, while even though the piezoelectric vibrator 3 and IC chip 4 mounted on the substrate 2 are molded by the molded resin layer 5, the F0 of the piezoelectric vibration device 1 can be easily adjusted by breaking the second metal film 9.

[0055] The piezoelectric vibration device according to the first embodiment of the present invention can be modified in various ways, and its modified form will be described below.

[0056] <Modification 1 of the first embodiment> First, let's describe the first modified example with reference to Figure 9. In this modified example, the second metal film 91 formed on the lower surface 2b, which is the other main surface of the substrate 2, is the same rectangular shape as the first metal film 8 (see Figure 4) on the upper surface 2a, as shown in Figure 9. Here, the corner of the second metal film 91 in the A2-B2 direction is connected to the second external connection terminal 25b.

[0057] When dividing the rectangular second metal film 91 shown in Figure 9, the frequency deviation ΔF between the resonant frequency of the prepared piezoelectric vibration device 1 and the target frequency is derived. The capacitance of the capacitance section C required to make the derived frequency deviation ΔF zero is derived, and the optimal cutting position of the second metal film 91 to achieve the derived capacitance is derived. The second metal film 91 at the derived position is then cut by irradiating it with laser light using, for example, a laser light irradiation device which is a cutting means, to melt and cut it together with the base film 7. This reduces the area of ​​the second metal film 91 as an electrode, lowers the capacitance of the capacitance section C, and adjusts the resonant frequency of the piezoelectric vibration device 1 to match the target frequency. Note that the cutting means for cutting the second metal film 91 is not limited to a laser light irradiation device, but may also be an electron beam irradiation device, or even a grinding machine instead of such a beam irradiation device, and it is desirable that it can perform cutting with high precision.

[0058] Thus, in the modified example 1, the second metal film 91 can be cut at any position using the laser light irradiation device, the capacitance of the capacitance section C can be adjusted with high precision, and the F0 of the piezoelectric vibration device 1 can be adjusted with greater precision.

[0059] <Modification 2 of the first embodiment> Modification 2 will be described with reference to Figure 10. In this modification, the second metal film 92 formed on the lower surface 2b, which is the other main surface of the substrate 2, is constructed as shown in Figure 10 by connecting the centers of three main parts 92a1, 92a2, and 92a3 of different sizes and adjacent main parts 92a1, 92a2, and 92a3 with a connecting part 92b. The main part 92a1 on the A2 side of the second metal film 92 is connected to the second external connection terminal 25b, which is an earth terminal.

[0060] Furthermore, the main part of the second metal film 92 consists of two smallest main parts 92a1, two next smallest main parts 92a2, and one largest main part 92a3. The dimensions of the entire second metal film 92 in the A1-A2 direction and the B1-B2 direction are the same as those of the first metal film 8 on the upper surface 2a side (see Figure 4).

[0061] According to this modified example 2, the same effect as in the first embodiment described above can be obtained by removing any of the connecting portions 92b.

[0062] In this modified example 2, only one of the main parts may have a different shape from the others, or all of the main parts may have different shapes. Furthermore, the shape of each main part is not limited to a rectangle as shown in Figure 10.

[0063] <Modification 3 of the First Embodiment> Modification 3 will be described with reference to Figure 11. In this modification, the second metal film 93 formed on the lower surface 2b, which is the other main surface of the substrate 2, is constructed by connecting two main parts 93a1 and 93a2 of different sizes with an H-shaped connecting part 93b, as shown in Figure 11. The main part 93a1 on the A2-B2 side of the second metal film 93 is connected to the second external connection terminal 25b.

[0064] Furthermore, the main part of the second metal film 93 consists of four parts: two small main parts 93a1 and two large main parts 93a3. The dimensions of the entire second metal film 93 in the A1-A2 direction and the B1-B2 direction are the same as those of the first metal film 8 on the upper surface 2a side (see Figure 4).

[0065] According to this modified example 3, the capacitance of the capacitance section C can be adjusted by cutting off the connecting portion 93b at a predetermined position and appropriately combining the four main portions 93a1 and 93a2 to vary the area of ​​the second metal film 93 as an electrode, thereby achieving the same effect as the first embodiment described above. In this case, the cutting position of the connecting portion 92b is not limited to one location, but may be two or more locations.

[0066] <Modification 4 of the First Embodiment> Modification 4 will be explained with reference to Figure 12. In this modification, as shown in Figure 12, another insulating substrate 201 is laminated on the upper surface (one main surface) 2a side of the insulating substrate 200 that constitutes the substrate 2, and the piezoelectric vibrator 3 and IC chip 4 are mounted on the upper surface of this insulating substrate 201. A first metal film 8 and a second metal film 9 are formed on the upper surface 2a and lower surface 2b, which are the two main surfaces of the lower insulating substrate 200, respectively, and the upper surface of the upper insulating substrate 201, that is, the mounting surface for the piezoelectric vibrator 3 and IC chip 4, is covered with a base material film 7.

[0067] According to this modified example 4, the gap between the first and second metal films 8 and 9 that form the capacitance portion C can be adjusted by the thickness of the insulating substrate 200. Therefore, by stacking two insulating substrates 200 and 201 to form the substrate 2, the strength of the substrate 2 can be maintained even if the thickness of the insulating substrate 200 forming the capacitance portion C is changed to a desired thickness. This allows for precise adjustment of F0 by appropriately selecting the variable amount of capacitance of the capacitance portion C by selecting the thickness of the insulating substrate 200 while maintaining the strength of the substrate 2.

[0068] <Second Embodiment> A piezoelectric vibration device 1A according to a second embodiment of the present invention will be described with reference to Figure 13. Furthermore, the following description will also refer to Figures 3 to 6.

[0069] The piezoelectric vibration device 1A according to the second embodiment differs from the piezoelectric vibration device 1 of the first embodiment in that, as shown in Figure 13, a capacitance section CA is provided in parallel with the load capacitor C1 between the input side (input side of the excitation electrode) of the piezoelectric vibrator 3 and the ground, and a capacitance section CB is provided in parallel with the load capacitor C2 between the output side (main side of the excitation electrode) of the piezoelectric vibrator 3 and the ground.

[0070] At this time, the first metal film 8 and the second metal film 9 are each divided into two parts, for example, in the center in the A1-A2 direction. Capacitive section CA is formed by one divided part of the first metal film 8 on the A2 side and one divided part of the second metal film 9, and capacitive section CB is formed by the other divided part of the first metal film 8 on the A1 side and the other divided part of the second metal film 9. By connecting the divided part of the second metal film 9 on the A2 side of capacitive section CA and the divided part of the second metal film 9 on the A1 side of capacitive section CB to the second external connection terminal 25b, which is the ground terminal, the circuit configuration shown in Figure 13 is obtained.

[0071] Then, the resonant frequency of the piezoelectric vibration device 1A is measured using a frequency measuring instrument, the frequency deviation ΔF between the measured frequency and the target frequency is derived, the optimal cutting position is selected for each of the divided portions of the second metal film 9 on the A2 and A1 sides so that the derived frequency deviation ΔF is approximately zero, the selected connecting portion 9b is cut off together with the base film 7 to divide each of the divided portions of the second metal film 9, and the resonant frequency of the piezoelectric vibration device 1A is adjusted by varying the area of ​​the electrodes of the divided portions of the second metal film 9 that form the capacitive portions CA and CB, respectively, thereby variably adjusting the capacitance of the capacitive portions CA and CB.

[0072] In this case, the original frequency of the piezoelectric vibration device 1A may be adjusted not only by adjusting the capacitance of both the capacitance section CA and CB, but also by adjusting only the capacitance of either the capacitance section CA or CB.

[0073] According to the second embodiment, the same effects as those of the first embodiment described above can be obtained.

[0074] <Third Embodiment> A piezoelectric vibration device 1B according to a third embodiment of the present invention will be described with reference to Figures 14 to 16. In Figures 14 to 16, the same reference numerals as in Figures 1 to 6 indicate the same or equivalent components, and the following description will also refer to Figures 1 to 6.

[0075] The piezoelectric vibration device 1B according to the third embodiment differs from the piezoelectric vibration device 1 of the first embodiment in that the piezoelectric vibrator 3B and the IC chip 4B are mounted on the upper surface 2Ba of the substrate 2B, and the present invention is applied to a differential type piezoelectric vibration device 1B that outputs two signals with a phase difference of 180°.

[0076] Similar to the first embodiment, as shown in Figure 14, L-shaped first to fourth external connection electrodes 32Ba, 32Bb, 32Bc, and 32Bd are formed in a counterclockwise direction in plan view at the four corners of the upper surface of the first sealing member, which is the upper surface of the piezoelectric vibrator 3B. Similar to the first embodiment, the first external connection electrode 32a is the output terminal of the piezoelectric vibrator 3, the second external connection electrode 32b is the input terminal of the piezoelectric vibrator 3, and the third external connection electrode 32c and the fourth external connection electrode 32d are ground terminals, respectively.

[0077] Furthermore, pads 24Ba to 24Bd for mounting the first to fourth ICs are formed in the recess 21Bd on the A1-B1 side of the upper surface 2Ba of the substrate 2B, and pads 24Be to 24Bh for mounting the fifth to eighth ICs are formed in the recess 21Bc on the A1-B2 side. For example, the pad 24Ba for mounting the first IC is the oscillation input terminal on the input side of the excitation electrode, and the first external connection terminal 24Ba of the IC chip 4B is electrically connected by wire W. The pad 24Bb for mounting the second IC is the oscillation output terminal on the output side of the excitation electrode, and the second external connection terminal 4Bb of the IC chip 4B is electrically connected by wire W. The pad 24Bc for mounting the third IC is the output enable terminal, and the third external connection terminal 4Bc of the IC chip 4B is electrically connected by wire W. The pad 24Bd for mounting the fourth IC is the power supply terminal, and the fourth external connection terminal 4Bd of the IC chip 4B is electrically connected by wire W. The fifth IC mounting pad 24Be is an external terminal used for data writing, frequency control, adjustment, and NC external terminals, and the fifth external connection terminal 4Be of IC chip 4B is electrically connected by wire W. The sixth IC mounting pad 24Bf is the second output terminal, and the sixth external connection terminal 4Bf of IC chip 4B is electrically connected by wire W. The seventh IC mounting pad 24Bg is the first output terminal, and the seventh external connection terminal 4Bg of IC chip 4B is electrically connected by wire W. The eighth IC mounting pad 24Bh is the ground terminal, and the eighth external connection terminal 4Bh of IC chip 4B is electrically connected by wire W.

[0078] As shown in Figure 15, six recesses 22Ba to 22Bf are formed on the peripheral edge of the lower surface 2b of the substrate 2B, including the four corners. Rectangular first to sixth external connection terminals 25Ba to 25Bf are formed in these recesses 22Ba to 22Bf, respectively. These first to fourth external connection terminals are used when mounting the piezoelectric vibration device 1 on other equipment (such as a wiring board), and are, for example, the following terminals: The first external connection terminal 25Ba is a power terminal, the fourth external connection terminal 25Bd is a first output terminal, the fifth external connection terminal 25Be is a second output terminal, the sixth external connection terminal 25f is a ground terminal, and the second external connection terminal 25Bb and the third external connection terminal 25Bc are other external terminals, used as output enable terminals, data writing external terminals, frequency control external terminals, adjustment external terminals, NC external terminals, etc.

[0079] Here, the substrate 2B is made of a single insulating substrate, similar to the first embodiment. A rectangular first metal film 8 is formed on its upper surface (one main surface) 2Ba, as shown in Figure 14, and covered with a base film 7. On the lower surface (the other main surface) 2Bb, a second metal film 9 is formed, as shown in Figure 15, consisting of 10 main parts 9za and 9 connecting parts 9b that connect the central parts of adjacent main parts 9a, and is covered with a base film 7. Here, the main part 9Ba on the A2 side is connected to the sixth external connection terminal (earth terminal) 25Bf. Then, similar to the first embodiment, the capacitance part C is formed by the first metal film 8 and the second metal film 9.

[0080] The circuit diagram of the piezoelectric vibration device 1B according to the third embodiment is shown in Figure 16. An inverter amplifier AMP3 is provided in parallel with the inverter amplifier AMP2. The output of amplifier AMP2 is used as the first output terminal OUT1, and the output of amplifier AMP3, which is obtained by inverting the phase of the output of amplifier AMP2, is used as the second output terminal OUT2. Signals with a phase difference of 180° are output from the first and second output terminals OUT1 and OUT2. A capacitive section C is provided in parallel with the load capacitor C1 on the input side (input side of the excitation electrode) of the piezoelectric vibrator 3.

[0081] According to the third embodiment, even with a differential piezoelectric vibration device 1B, the same effects as those of the first embodiment described above can be obtained.

[0082] It should be noted that the present invention is not limited to the above-described configuration, and various design modifications can be made within the scope of the matters described in the claims.

[0083] For example, in the embodiment described above, the case in which the first and second metal films 8, 9, 91, 92, and 9B are formed approximately in the center of the upper and lower surfaces of the substrates 2 and 2B was explained. However, the formation position is not limited to the center of the substrates 2 and 2B, and it is sufficient that they are formed in a position that does not overlap with the external connection terminals 25a to 25d and 25Ba to 25Bf on the lower surface side of the substrates 2 and 2B.

[0084] Furthermore, the connecting portions 9b, 92b, and 93b in the first embodiment described above may connect adjacent main portions 9a, 92a1, 92a2, 92a3, 93a1, and 93a2 to parts other than the central portion.

[0085] Furthermore, the output side of the piezoelectric vibrator 3B of the third embodiment described above may also be provided with a capacitance section composed of the first and second metal films, as in the second embodiment.

[0086] Furthermore, in the above-described embodiment, the first metal film 8 and the second metal film 9 were formed on the upper surface 2a and the lower surface 2b of the substrate 2, respectively. However, the capacitance portion may be formed by forming the first metal film 8 and the second metal film 9 on the lower surface 2b of the substrate 2.

[0087] Furthermore, although the above-described embodiments described a case in which the piezoelectric vibrator 3 and IC chip 4 mounted on the substrate 2 are molded by the molded resin layer 5, the present invention can be similarly applied to non-molded piezoelectric vibration devices to perform F0 adjustment.

[0088] Furthermore, the modifications 1 to 4 of the first embodiment described above may be appropriately combined with the second or third embodiment.

[0089] Furthermore, although the vibrating part of the piezoelectric vibration element is described as rectangular (AT cut) in the above-described embodiment, it is not limited to this, and may be rectangular (SC cut, etc.) or tuning fork shaped (BT cut).

[0090] Furthermore, the IC chip 4 may also include a temperature compensation circuit.

[0091] Furthermore, the embodiments and modifications described above are applicable to both SPXO (Simple Packaged Crystal Oscillator) and TCXO (Temperature Compensated Crystal Oscillator).

[0092] The present invention is widely applicable to piezoelectric vibration devices comprising a substrate, a piezoelectric vibrator mounted on the substrate, and integrated circuit elements. [Explanation of Symbols]

[0093] 1,1A,1B: Piezoelectric vibration device 2, 2B: Circuit board 2a, 2Ba: Top surface (one of the main surfaces) 2b, 2Bb: Bottom surface (the other main surface) 3,3B: Piezoelectric vibrator 4,4B: IC chip (integrated circuit element) 5: Sealing layer (Mold sealing layer) 25a~25d, 25Ba~25Bf: External connection terminals 8: First metal film 9,91,92,9B: Second metal film 9a,92a1.92a2,92a3,93a1,93a2,9Ba:Main part 9b,92b,93b,9Bb: Connection part C, CA, CB: Capacitance part

Claims

1. A piezoelectric vibration device comprising a substrate, a piezoelectric vibrator mounted on the substrate, and an integrated circuit element, The piezoelectric vibrator is, A piezoelectric vibrating element having a pair of excitation electrodes, The system comprises a sealing member for sealing the piezoelectric vibration element, The aforementioned integrated circuit element is The piezoelectric vibration element comprises an oscillation amplification circuit to which the input terminal and output terminal are connected to the input side and output side, respectively, of the pair of excitation electrodes. The substrate comprises at least one insulating substrate, The insulating substrate is One main surface on the side on which the piezoelectric vibrator and the integrated circuit element are mounted, The other main surface is provided with external connection terminals, A first metal film connected to the input and / or output side of the piezoelectric vibrator, A second metal film is formed in a position that does not overlap with the external connection terminal and is grounded, and together with the first metal film, constitutes a capacitive portion. Except for a portion of each of the two main surfaces of the substrate, the substrate comprises an insulating base film covering the surface of each of the two main surfaces of the substrate, including the first metal film and the second metal film. A piezoelectric vibration device characterized in that the second metal film is formed to be separable by being cut together with the base film at at least one location.

2. The first metal film is formed on one of the main surfaces of the substrate. The piezoelectric vibration device according to claim 1, characterized in that the second metal film is formed on the other main surface of the substrate at a position opposite to the first metal film.

3. The piezoelectric vibration device according to claim 1 or 2, characterized in that the capacitance portion is connected in series with the excitation electrode of the piezoelectric vibrator that is connected to the input terminal of the oscillation amplification circuit.

4. The second metal film is Multiple main parts formed at predetermined intervals, It comprises a plurality of connecting parts that connect the aforementioned main parts, The piezoelectric vibration device according to claim 1 or 2, characterized in that one of the connecting portions and the base film covering the connecting portion are cut off, thereby severing the other metal film.

5. The piezoelectric vibration device according to claim 4, characterized in that the plurality of main parts have substantially the same shape.

6. The piezoelectric vibration device according to claim 4, characterized in that at least one of the plurality of main parts has a different shape from the others.

7. The piezoelectric vibration device according to claim 1 or 2, characterized in that the substrate film of the insulating substrate is light-transmitting.

8. The piezoelectric vibration device according to claim 1 or 2, further comprising a molded resin layer covering the piezoelectric vibrator and the integrated circuit element mounted on the substrate.

9. In a method for manufacturing a piezoelectric vibration device according to claim 1 or claim 2, Preparation steps for preparing the piezoelectric vibration device, A measurement step in which the resonant frequency of the prepared piezoelectric vibration device is measured using a measuring means, A derivation step in which the frequency deviation between the measurement frequency in the measurement step and a preset target frequency is derived using a derivation means, An adjustment step is to set a division position for the second metal film where the frequency deviation derived in the derivation step becomes approximately zero, and to divide the second metal film at the division position to variably adjust the capacitance of the capacitance section. A method for manufacturing a piezoelectric vibration device, characterized by comprising the above.

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