JP6708224B2 - Tuning fork vibrator manufacturing method - Google Patents

Description

The present invention relates to a method of manufacturing a tuning fork type vibrator used as a clock source for various electronic devices.

The tuning fork type oscillator is built in together with the oscillation circuit in various electronic devices including a clock as a clock source.

In such a tuning fork type vibrator, when the tuning fork type resonator element cantilevered in the package is bent in the thickness direction due to an external impact, the arm of the tuning fork type resonator element has the highest frequency due to damage. The fluctuating tip may come into contact with the bottom surface of the package, receive a large impact, and its corner may be chipped.

Therefore, for example, in Patent Document 1, a pillow portion is provided on the bottom surface of the package, and when the tuning-fork type vibrating piece is bent by impact, a portion in the middle of the arm portion comes into contact with the pillow portion. This prevents the tip of the arm from hitting the bottom of the package and damaging it.

Japanese Patent No. 5175128

In recent years, with the miniaturization of various electronic devices, the built-in tuning fork type vibrator has an ultra-small size such that the external dimensions of a rectangular shape in plan view are 1.2 mm×1.0 mm or less and the thickness is 0.35 mm or less , Thin type is required.

In such an ultra-small and thin tuning fork type vibrator, even if the pillow portion is provided on the bottom surface of the package as described above, frequency fluctuation may occur due to external impact or the like.

This is because even if the tip of the arm portion of the tuning fork type vibrating piece is prevented from coming into contact with the bottom surface of the package by the pillow portion when the tuning fork type vibrating piece is bent in the thickness direction due to an external impact. This is because the tip of the arm portion of the tuning-fork type vibrating piece comes into contact with the upper surface of the package, that is, the inner surface of the lid, and the corner thereof is cut off, resulting in frequency fluctuation.

The present invention has been made in view of the above points, and an object of the present invention is to provide a method of manufacturing a tuning fork type vibrator having good shock resistance in which frequency fluctuation is suppressed.

In order to achieve the above object, the present invention is configured as follows.

That is, in the method for manufacturing a tuning fork type vibrator of the present invention, a plurality of tuning fork type vibrating pieces are integrally connected to a wafer, and a base portion of the tuning fork type vibrating piece and a plurality of arm portions extending from the base portion. A step of forming an electrode on the second step, a second step of forming a frequency adjusting metal film on an end of the one main surface of the front and back main surfaces of the arm portion in the extending direction, and a second step of forming the electrode on the end The third step of removing a part of the frequency adjusting metal film to adjust the frequency, and the tuning fork type vibrating pieces divided into individual tuning fork type vibrating pieces are housed in a housing part of the package body to be packaged. And a fourth step of sealing the opening of the device with a lid,
The extending direction end portion where the frequency adjusting metal film is formed in the second step is a wide end portion in the width direction orthogonal to the extending direction, and in the fourth step, each tuning fork is formed. The mold vibrating piece has the base portion joined to the electrode of the housing portion of the package body so that the one main surface faces the lid, and the first target frequency of the tuning fork type vibrating piece in the first step is The ratio of the absolute value of the difference in frequency between the second target frequency and the third target frequency in the third step to the absolute value of the difference in frequency from the second target frequency in the second step is 0.5 or less. In the second step, the frequency adjusting metal film is formed to have a thickness of 9 μm or more and 15 μm or less, and in the third step, the frequency adjusting metal film is formed on the wide end portion of the arm portion in the extending direction. The frequency adjusting metal film, from the tip of the wide end, toward the base side along the extending direction, half or less of the length of the frequency adjusting metal film along the extending direction. The material of the tuning fork type resonator element is removed so as to be exposed over the length , and the frequency adjusting metal film formed in the second step has a thickness of t (μm), When the distance from the inner surface of the lid to the portion of the arm where the frequency adjusting metal film is not formed is H (μm), t/H is 0.25≦t/H≦0.43. ..

According to the method of manufacturing a tuning fork type vibrator of the present invention, the first target frequency in the first step of forming electrodes on the plurality of arms and the second step of forming the frequency adjusting metal film on the end portions of the arms. 2 With respect to the absolute value of the difference in frequency from the target frequency, the second target frequency and the frequency of the third target frequency in the third step of adjusting the frequency by removing a part of the frequency adjusting metal film are adjusted. Since the ratio of the absolute value of the difference is 0.5 or less, compared with the change width of the frequency in the case of shifting from the first target frequency of the first step to the second target frequency of the second step, When the frequency shifts from the second target frequency to the third target frequency in the third step, the change width of the frequency becomes as small as 0.5 or less, that is, the frequency adjusting metal formed at the end of the arm in the second step. The ratio of the amount of the frequency adjusting metal film removed in the third step to the amount of the film formed becomes small.

As a result, after the frequency adjusting metal film is partially removed in the third step to adjust the frequency, the frequency adjusting metal film can be sufficiently left, and the impact from the outside causes the tuning fork type vibrating piece to move. When the arm portion is bent toward the lid body, the remaining frequency adjusting metal film can be brought into contact with the inner surface of the lid body, whereby the tip of the arm portion comes into contact with the inner surface of the lid body. Can be prevented and chipping of the corner at the tip can be prevented.

In addition, since the thickness of the frequency adjusting metal film is as thick as 9 μm or more, even if a part of the metal film is removed for frequency adjustment, the tuning fork-type vibrating piece is sufficiently left by the impact from the outside. When bent, the remaining frequency-adjusting metal film can come into contact with the inner surface of the lid, and the impact at the time of contact can be sufficiently mitigated.

Further, the frequency adjusting metal film is removed from the tip of the wide end along the longitudinal direction of the arm over a length of half or less of the length, that is, the frequency adjusting metal film is , The remaining frequency adjusting metal film remains when the tuning-fork vibrating piece is bent toward the lid due to an external impact, because the remaining metal film for frequency adjustment remains in the lid. It is possible to prevent the tip of the arm portion from coming into contact with the inner surface of the lid body to prevent the corner portion from being chipped.

According to the present invention, when the tuning-fork vibrating piece is bent in the thickness direction due to an external impact, the frequency adjusting metal film on the way to the tip of the arm portion, which is the free end, becomes Since it contacts the inner surface, the tip of the arm portion does not contact the inner surface of the lid, and therefore, it is possible to prevent the corner portion at the tip of the arm portion having the largest frequency fluctuation from being damaged due to damage. As a result, it is possible to obtain a tuning fork type vibrator having excellent shock resistance by suppressing the frequency fluctuation due to the shock from the outside.

FIG. 1 is a schematic cross-sectional view of a tuning fork type crystal resonator obtained by a manufacturing method according to an embodiment of the present invention. FIG. 2 is a plan view of the tuning fork type crystal resonator of FIG. 1 with a lid removed. FIG. 3 is a view showing one main surface side of the tuning fork type crystal vibrating piece. FIG. 4 is a view showing the other main surface side of the tuning fork type crystal vibrating piece. FIG. 5 is a diagram for explaining coarse frequency adjustment by irradiating a tuning fork type quartz vibrating piece with a laser beam. FIG. 6 is a schematic cross-sectional view showing the vicinity of the tip of the tuning-fork type crystal vibrating piece housed in the package. FIG. 7 is a diagram for explaining target frequencies of the electrode forming step, the weighting step, and the laser processing step. FIG. 8 is a diagram corresponding to FIG. 7 of the conventional example. FIG. 9 is a view corresponding to FIG. 4 of a tuning fork type crystal resonator obtained by a manufacturing method according to another embodiment of the present invention. FIG. 10 is a schematic sectional view corresponding to FIG. 6 of the embodiment of FIG. FIG. 11 is a view corresponding to FIG. 4 of a tuning fork type crystal resonator obtained by a manufacturing method according to still another embodiment of the present invention. 12 is a schematic sectional view corresponding to FIG. 6 of the embodiment of FIG. FIG. 13 is a view corresponding to FIG. 4 of a tuning fork type crystal resonator obtained by a manufacturing method according to still another embodiment of the present invention. FIG. 14 is an outline view of a tuning-fork type crystal vibrating piece according to another embodiment of the present invention. FIG. 15 is an outline view of a tuning fork type crystal vibrating piece according to still another embodiment of the present invention. FIG. 16 is an outline view of a tuning fork type crystal vibrating piece according to another embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[Embodiment 1]
1 is a schematic cross-sectional view of a tuning fork type crystal resonator manufactured by a manufacturing method according to an embodiment of the present invention, and FIG. 2 is a plan view of a state in which a lid 5 of FIG. 1 is removed, FIG. 3 is a view showing one main surface side of the tuning fork type crystal vibrating piece 3, and FIG. 4 is a view showing another main surface side of the tuning fork type crystal vibrating piece 3. 3 and 4, the tuning-fork type crystal vibrating piece 3 shows a state before a part of the frequency adjusting metal films 19 and 20 is removed by the irradiation of the laser beam, for convenience of description. Further, FIG. 2 shows a state in which the base material of the crystal 26 is exposed by removing a part of the frequency adjusting metal films 19 and 20 by the irradiation of the laser beam.

The tuning fork crystal resonator 1 obtained by the manufacturing method of this embodiment has a tuning fork crystal vibrating piece 3 housed in a package 2 made of ceramic or the like. In the package 2, a base 4 as a package body and a lid 5 are joined via a sealing member 6. Specifically, the tuning-fork type crystal vibrating piece 3 is bonded to the pair of electrode pads 7, 7 of the base 4 having an open upper portion through the pair of metal bumps 8, 8 as a bonding material, and the opening of the base 4 is formed. The plate-like lid 5 is joined so as to seal the. The bonding material is not limited to the metal bump 8 and may be a conductive resin adhesive, a brazing material, or the like.

The nominal frequency of the tuning fork crystal oscillator 1 of this embodiment is 32.768 kHz. Note that the nominal frequency is an example, and can be applied to other frequencies.

The base 4 of the package 2 is an insulating container body made of a ceramic material or a glass material. In the present embodiment, the base 4 is made of a ceramic material and is formed by firing. The base 4 has a peripheral wall portion 4a on the periphery thereof and has a concave cross-sectional shape with an opening at the top, and the inside of the base 4 serves as a storage portion for the tuning-fork type crystal vibrating piece 3. A pair of the electrode pads 7, 7 are formed on the bottom surface of one end side of the base 4 in the longitudinal direction (left and right direction in FIGS. 1 and 2), and the base 4 is provided with a wiring pattern (not shown). It is electrically connected to a terminal electrode (not shown) on the back surface. When the cantilever-supported tuning-fork type crystal vibrating piece 3 is bent toward the bottom side of the base 4 by the impact from the outside, the tuning fork that is the free end side is formed on the bottom surface of the base 4 on the other end side in the longitudinal direction. The pillow portion 9 for preventing the tip of the crystal vibrating piece 3 from coming into contact with the bottom surface of the base 4 and being damaged extends in the direction orthogonal to the longitudinal direction of the base 4 (the vertical direction in FIG. 2 ). It is provided.

The lid 5 is made of, for example, a metal material, a ceramic material, a glass material, or the like, and is formed into a single plate having a rectangular shape in plan view. In this embodiment, the lid 5 is made of a metal material.

The tuning fork crystal resonator 1 of this embodiment is an ultra-small and thin tuning fork crystal resonator, and the package 2 has a rectangular outer dimension of 1.2 mm×1.0 mm, for example. The thickness (height) including 5 is 0.35 mm, for example.

It should be noted that the present invention is not limited to the outer dimensions, and for example, the outer dimensions of the tuning-fork type crystal resonator package in plan view are, for example, 2.0 mm×1.6 mm or 1.6 mm×1. It may be 0.0 mm, and the thickness including the lid 5 may be 0.45 mm, for example.

In this embodiment, the thickness t1 of the bottom portion of the base 4 shown in FIG. 1 is, for example, 0.09 mm, and the thickness (height) t2 of the peripheral wall portion 4a of the base 4 is, for example, 0.15 mm, Since the tuning fork type crystal vibrating piece 3 having a thickness of, for example, about 0.08 mm is housed in the recess of the base 4, the vertical clearance of the tuning fork type crystal vibrating piece 3 in the package 2 is, for example, about 0.035 mm. Becomes

The tuning fork type crystal vibrating piece 3 is molded from a single crystal wafer (not shown), and the outer shape of the tuning fork type crystal vibrating piece 3 is formed by, for example, wet etching using a resist or a metal film as a mask by using a photolithography technique (photolithography method). It is molded in a large number by.

As shown in FIGS. 3 and 4, the tuning-fork type crystal vibrating piece 3 includes a base portion 10 and a pair of first and second arm portions 11 which are vibrating portions extending in parallel from one end face side of the base portion 10. , 12 and. The base portion 10 includes a joint portion 13 extending in a direction opposite to the extending direction of the first and second arm portions 11 and 12 and joined to the base 4. The joint portion 13 of this embodiment extends in a direction opposite to the extending direction of the first and second arm portions 11 and 12, and further one of the directions orthogonal to the extending direction (right side in FIG. 3). Extending to.

In the pair of first and second arm portions 11 and 12, the tip portions 11a and 12a thereof are orthogonal to the extending direction of the arm portions 11 and 12, that is, the width direction (Fig. 3, the width is wide in the left-right direction in FIG. 4, and the width is W1 as shown in FIG. As shown in FIG. 2, the pillow portion 9 on the bottom surface of the base 4 is provided so as to be opposed to the wide area having the width W1 of the tip portions 11a and 12a of the first and second arm portions 11 and 12. .. The protrusion height of the pillow portion 9, that is, the thickness is, for example, 0.01 mm.

Further, in the first and second arm portions 11 and 12, groove portions 14 and 14 extending along the extending direction of the arm portions 11 and 12 are provided on both main surfaces shown in FIGS. 3 and 4, respectively. Has been formed.

The tuning fork type crystal vibrating piece 3 has two first excitation electrodes 15 and a second excitation electrode 16, and in order to electrically connect the respective excitation electrodes 15 and 16 to the electrode pads 7 and 7 of the base 4, respectively. , And extraction electrodes 17 and 18 extracted from the excitation electrodes 15 and 16, respectively. Part of the two first and second excitation electrodes 15 and 16 is formed inside the groove portions 14 and 14 on both main surfaces.

The first excitation electrode 15 is formed on both main surfaces of the first arm portion 11 including the groove portion 14 and both side surfaces of the second arm portion 12, and is commonly connected to the extraction electrode 17. Similarly, the second excitation electrode 16 is formed on both main surfaces including the groove portion 14 of the second arm portion 12 and both side surfaces of the first arm portion 11, and is commonly connected to the extraction electrode 18.

In addition, arm tip electrodes 25 and 24 are formed over the entire peripheries of the wide regions of the tip portions 11a and 12a of the first arm portion 11 and the second arm portion 12, respectively. The arm tip electrode 25 formed on the entire circumference of the tip portion 11a is connected to the second excitation electrodes 16 formed on both side surfaces of the first arm portion 11, and the arm formed on the entire circumference of the tip portion 12a. The tip electrode 24 is connected to the first excitation electrode 15 formed on both side surfaces of the second arm portion 12.

On the arm tip electrodes 25, 24 of each of the wide tip portions 11a, 12a on the one main surface side shown in FIG. 3, the mass of the metal film is reduced by irradiating a beam such as a laser beam to tune the tuning fork crystal. The frequency adjusting metal films 19 and 20 for roughly adjusting the frequency of the piece 3 are formed in a slightly smaller area than the arm tip electrodes 25 and 24. The frequency adjusting metal films 19 and 20 extend to the tips of the arms 11 and 12, that is, the tips of the wide tips 11a and 12a, respectively.

As shown in FIG. 1, the frequency adjusting metal films 19 and 20 of which a part is removed by the irradiation of the beam are opposed to the inner surface of the lid body 5. As will be described later, the frequency adjusting metal films 19 and 20 cover the lid body 5 when the arm portions 11 and 12 of the tuning-fork type crystal vibrating piece 3 are bent toward the lid body 5 by an external impact. By abutting on the inner surface of the, the tips of the wide tip portions 11a, 12a, which are the free ends of the arm portions 11, 12, are prevented from abutting on the inner surface of the lid 5.

For the first and second excitation electrodes 15 and 16, the extraction electrodes 17 and 18 and the arm tip electrodes 24 and 25 of the tuning fork type crystal vibrating piece 3, a chromium layer is formed on each arm portion 11 and 12 by metal vapor deposition. It is a thin film formed by forming a metal such as gold on a chrome layer. This thin film is formed on the entire surface of the substrate by a method such as a vacuum deposition method or a sputtering method, and then metal-etched by a photolithography method to form a desired shape. The first and second excitation electrodes 15 and 16, the extraction electrodes 17 and 18, and the arm tip electrodes 24 and 25 are not limited to chromium and gold, but may be chromium or silver.

The frequency adjusting metal films 19 and 20 formed on the respective tip portions 11a and 12a, which are free ends of the arm portions 11 and 12, are formed by plating, for example, by a method such as electrolytic plating. When forming 19 and 20 by plating, it is preferable that they are formed at the same time in the same step as the metal bump 8 described later. In the present embodiment, gold (Au) is used as the frequency adjusting metal films 19 and 20.

The extraction electrode 17 drawn from the first excitation electrode 15 is extendedly formed on the first bonding portion 13b on one end side of the bonding portion 13, and the second excitation electrode 16 is formed on the second bonding portion 13a on the other end side. The extracted extraction electrode 18 is extended.

Two metal bumps 8, 8 made of, for example, gold are formed on the bonding portion 13 on the other main surface side shown in FIG. 4, which are bonding portions with the electrode pads 7, 7 of the base 4. Specifically, one metal bump 8 is formed on the extraction electrode 17 extracted from the first excitation electrode 15 of the first bonding portion 13b, and the other metal bump 8 is formed on the second bonding portion 13a. It is formed on the extraction electrode 18 extracted from the second excitation electrode 16. The joint portion 13 forming a part of the base portion 10 is joined to the respective electrode pads 7, 7 of the base 4 and functions as a support portion for supporting the tuning-fork type crystal vibrating piece 3. The shape of the metal bumps 8 in plan view is elliptical, but may be circular, or polygonal including rectangular and square. The metal bumps 8 and 8 are formed by plating by a method such as electrolytic plating.

As described above, the width W1 of the tip portions 11a and 12a of the first and second arm portions 11 and 12 on which the frequency adjusting metal films 19 and 20 are formed is wider than the width W2 of other portions. The width is wide, and in this embodiment, it is, for example, three times or more the width of other portions.

The tip portions 11a and 12a of the first and second arm portions 11 and 12 on which the frequency adjusting metal films 19 and 20 are formed are wide for the following reason.

The frequency of the tuning fork crystal resonator is inversely proportional to the square of the length of the arm of the tuning fork crystal vibrating piece and is proportional to the width of the arm. Therefore, if the length of the arm portion of the tuning fork type resonator element is shortened in order to make the tuning fork type crystal unit extremely small, the frequency becomes large. It is necessary to increase the formation area of the metal film which becomes the weight for adjusting the frequency on the side. Note that it is possible to reduce the width of the arm portion to suppress the frequency from increasing, but if the width of the arm portion is narrowed, the CI (crystal impedance) value becomes extremely poor.

Therefore, if the length of the arm is shortened in order to reduce the size of the tuning fork type crystal resonator without deteriorating the CI value, the metal for frequency adjustment becomes the weight of the tuning fork type crystal resonator element. The tip where the film is formed becomes larger and wider.

When the tip portions 11a and 12a of the arm portions 19 and 20 of the tuning-fork type crystal vibrating piece 3 are large in this way, they are easily bent by an external impact.

Further, if the tuning fork type crystal resonator 1 is made thinner, the vertical clearance of the tuning fork type crystal vibrating piece 3 in the package 2 becomes smaller.

Therefore, in this embodiment, when the pillow portion 9 is provided on the bottom surface of the base 4 and the tuning-fork type crystal vibrating piece 3 supported in a cantilever manner is bent to the bottom surface side of the base 4 by an external impact. By contacting the pillow part 9 with the part in the middle of the free ends of the arms 11 and 12, the ends of the arms 11 and 12 whose frequency fluctuates most due to damage, that is, the wide ends The tips of the tip portions 11a and 12a are prevented from coming into contact with the bottom surface of the base 4. This prevents the wide end portions 11a and 12a of the arm portions 11 and 12 from being chipped at the corner portions of the distal ends thereof.

Further, in this embodiment, the frequency adjusting metal films 19 and 20 of which a part is removed by the irradiation of the laser beam are opposed to the inner surface of the lid body 5 and are tuned from the outside by the impact from the outside. When 3 bends to the lid 5 side, it abuts on the inner surface of the lid 5, and the tips of the wide end portions 11a, 12a of the respective arm portions 11, 12 abut the inner surface of the lid 5. To prevent the corner portions at the tips of the arm portions 11 and 12 from being chipped.

Here, the frequency adjusting metal films 19 and 20 that are partially removed by the irradiation of the laser beam will be described.

In the tuning fork type crystal resonator 1 obtained by the manufacturing method of this embodiment, an electrolytic plating method or the like is provided on one main surface side of each arm portion 11 and 12 of each tuning fork type crystal vibrating piece 3 in the state of the crystal wafer. The metal films 19 and 20 for frequency adjustment are formed by, and a part of the metal films 19 and 20 for frequency adjustment is removed by irradiation of a laser beam to reduce the mass, and the frequency is roughly adjusted.

FIG. 5 is a diagram for explaining coarse frequency adjustment by laser beam irradiation. In FIG. 5, the state of irradiation of the laser beam on the frequency adjusting metal film 19 of the tip portion 11a of the first arm portion 11 of the both arm portions 11 and 12 is shown as a representative, but the second arm portion is not shown. The same applies to the irradiation of the laser beam on the frequency adjusting metal film 20 at the tip portion 12a of the reference numeral 12.

This laser beam irradiation is for adjusting the frequency on one main surface side by facing a laser beam irradiation source (not shown) to the other main surface side of each tuning fork type crystal vibrating piece 3 in the state of the crystal wafer. The metal film 19 is removed.

The irradiation of this laser beam starts scanning along the width direction of the first arm 11 (perpendicular to the paper surface of FIG. 5) from the tip side (the right side of FIG. 5) where the increase in frequency due to the decrease in mass is the largest. Then, the first arm 11 is sequentially moved toward the base 10 side (left side in FIG. 5) and scanned.

The radiated laser beam passes through the crystal 26 inside the tuning fork type crystal vibrating piece 3 from the other main surface side of each tuning fork type crystal vibrating piece 3 in the state of the crystal wafer, and on the opposite main surface side. The metal film 19 for frequency adjustment formed on the above is reached, and the arm tip electrodes 25 and the metal film 19 for frequency adjustment on both main surfaces are removed.

In this way, the frequency adjusting metal film 19 is irradiated with the laser beam from above so as to pass through the crystal 26 inside the tuning-fork type crystal vibrating piece 3 to adjust the frequency formed only on one main surface side. Since the metal film for use in removing 19 is removed, it is possible to prevent the metal scraps of the metal film for adjusting frequency 19 from scattering downwards away from the metal film for adjusting frequency 19 and reattaching to the tuning-fork type crystal vibrating piece 3. You can The frequency adjustment metal film may be irradiated with a laser beam from below so as to pass through the crystal inside the tuning-fork type crystal vibrating piece. Further, the frequency adjusting metal film may be formed on each of both main surfaces of the tuning fork type quartz vibrating piece. Although a green laser is used as the laser beam in this embodiment, a YAG laser or a laser having another wavelength may be used.

As described above, each tuning fork type quartz vibrating piece in the state of the quartz wafer is irradiated with the laser beam to remove a part of the frequency adjusting metal film to perform the coarse frequency adjustment. In the manufacture of the crystal vibrating piece, the amount of frequency adjustment in this rough adjustment has to be increased.

That is, in an ultra-small tuning fork-type crystal resonator having an outer dimension in plan view of, for example, 1.2 mm×1.0 mm or less, the built-in tuning-fork-type crystal vibrating piece is also extremely small. The manufacturing of such ultra-small tuning fork-type crystal vibrating piece requires a high degree of processing accuracy. However, the processing accuracy is limited. The variation in the frequency of the crystal vibrating piece becomes large, and in order to keep this large variation in the frequency within the required frequency range, the frequency adjustment amount in the rough adjustment must be increased.

In order to increase the amount of frequency adjustment in the rough adjustment performed by irradiating the frequency adjustment metal film with the laser beam, it is necessary to thicken the frequency adjustment metal film from the viewpoint of the restriction of the formation region of the frequency adjustment metal film. is there.

Further, in the present embodiment, as described above, the frequency adjusting metal films 19 and 20 partially removed by the laser beam irradiation are applied to each arm of the tuning fork type quartz vibrating piece 3 by an external impact. When the portions 11 and 12 are bent toward the lid body 5, they are brought into contact with the inner surface of the lid body 5, so that the frequency adjusting metal films 19 and 20 are thick, for example, 9 μm or more. The frequency adjusting metal films 19 and 20 of this embodiment are formed by plating as described above, and the film thickness thereof is, for example, about 10 μm.

In the state of the crystal wafer, a large number of tuning-fork type crystal vibrating pieces 3 whose frequency is roughly adjusted by laser beam irradiation are separated from the crystal wafer as individual tuning-fork type crystal vibrating pieces 3, and the base 4 of the package 2 is separated. The electrode pad 7 is bonded and mounted. The final frequency fine adjustment is performed with the tuning fork type crystal vibrating piece 3 bonded to the electrode pad 7 of the base 4 of the package 2. However, the frequency fine adjustment metal films 19 and 20 do the fine frequency adjustment. Since it is formed only on the one main surface side to be performed, it is efficient and the amount of metal used can be reduced.

FIG. 6 is a schematic cross-sectional view showing the vicinity of the tip portion of the tuning fork type crystal vibrating piece 3 stored in the package 2. In FIG. 6, of the two arm portions 11 and 12, the tip portion 11a of the first arm portion 11 is shown as a representative, but the tip portion 12a of the second arm portion 12 is also the same.

In the tuning fork type crystal vibrating piece 3, in the state of being housed in the package 2, the frequency adjusting metal film 19 formed on one main surface side faces the inner surface of the lid 5, and the other main surface side is It faces the bottom surface of the base 4.

As shown in FIG. 6, a pillow portion 9 is provided on the bottom surface of the base 4, and when the tuning fork type crystal vibrating piece 3 supported in a cantilever manner is bent by an external impact, the first arm portion 11 When the abutting portion 11b on the way to the tip of the base 4 comes into contact with the pillow portion 9, the tip of the first arm 11 where the frequency fluctuates most due to damage, that is, the tip of the wide tip 11a, So that it does not touch the bottom of the. Similarly, the abutting portion 12b (not shown) on the way to the tip of the second arm portion 12 abuts on the pillow portion 9, so that the tip of the wide tip portion 12a of the second arm portion 12 becomes the base. The bottom of 4 is not touched.

In the rough adjustment of the frequency by the irradiation of the laser beam performed in order to keep the frequency of each tuning fork type crystal vibrating piece 3 within the required frequency range, the removal amount of the frequency adjusting metal films 19 and 20 is equal to each tuning fork type crystal. In this embodiment, after the rough adjustment by the irradiation of the laser beam is performed, the frequency adjusting metal films 19 and 20 are arranged in the longitudinal direction of the arm portions 11 and 12 (see FIG. 6). Along the left-right direction), more than half of the region for forming the frequency adjusting metal film in the longitudinal direction remains.

That is, the length L2 in the longitudinal direction of the frequency adjusting metal films 19 and 20 shown in FIG. 6 after the rough adjustment is performed is the same as the frequency adjusting metal film 19 shown in FIG. 5 before the rough adjustment is performed. , 20, the length in the longitudinal direction is L1,
L2>0.5L1
I am trying.

In this embodiment, the L1 is, for example, 0.2 mm, and thus the L2 is, for example, longer than 0.1 mm.

In this way, the frequency adjustment metal films 19 and 20 removed by the irradiation of the laser beam are half or less of the length L1 along the longitudinal direction, that is, the frequency adjustment metal films 19 and 20 have their lengths longer than the length L1. Since the remaining length exceeds the half of the length L1 along the direction, each of the arm portions 11 and 12 of the tuning-fork type crystal vibrating piece 3 remains when the arm portions 11 and 12 bend toward the lid body 5, 20 abuts on the inner surface of the lid body 5, thereby preventing the tip ends of the respective arm portions 11 and 12, that is, the tip ends of the wide tip portions 11a and 12a from abutting on the inner surface of the lid body 5, It is possible to prevent the corners of the tips of the arms 11 and 12 from being chipped.

Further, since the thickness t of the frequency adjusting metal films 19 and 20 is as thick as 9 μm or more, the shock when the frequency adjusting metal films 19 and 20 come into contact with the inner surface of the lid 5 is buffered. You can

Further, as described above, the length L2 in the longitudinal direction of the frequency adjusting metal films 19 and 20 after the rough adjustment is performed exceeds, for example, 0.1 mm, so that the frequency adjusting metal films 19 and 20 are removed. The length d from the tip of the cut portion is, for example, 0.1 mm or less. The length d of the portions of the frequency adjusting metal films 19 and 20 removed by the laser beam irradiation is different for each tuning fork type quartz vibrating piece as described above, and may be d=0.

Here, if the length of the tuning-fork type crystal vibrating piece 3 shown in FIG. 3 is L, in this embodiment, L is 0.9 mm, for example.

Therefore, the ratio of the length d of the portions of the frequency adjusting metal films 19 and 20 removed by the laser beam irradiation to the length L of the tuning fork type quartz vibrating piece 3 is 0.1 mm or less.
d/L≦0.1/0.9=0.11
That is,
d/L≦0.11
Becomes

Further, when the thickness of the frequency adjusting metal films 19 and 20 is t, and the interval from the inner surface of the lid 5 to the portion of the arm 11 where the frequency adjusting metal films 19 and 20 are not formed is H, this implementation In the embodiment, it is preferable that the interval H is, for example, 35 μm, and the thickness t of the frequency adjusting metal films 19 and 20 is, for example, 9 μm or more and 15 μm or less.

Therefore, the ratio t/H of the thickness t of the frequency adjusting metal films 19 and 20 to the interval H is
9/35=0.257
15/35 = 0.429
Next to
The preferred range is
0.25≦t/H≦0.43
Becomes

That is, the ratio of the thickness t of the frequency adjusting metal films 19 and 20 to the interval H is preferably 0.25 or more and 0.43 or less.

When the thickness t of the frequency adjusting metal films 19 and 20 is less than 9 μm, the arm portions 11 and 12 of the tuning fork type crystal vibrating piece 3 are bent toward the lid body 5 due to an external impact. Sometimes, before the remaining frequency adjusting metal films 19 and 20 come into contact with the inner surface of the lid body 5, the tips of the wide tip portions 11a and 12a of the arm portions 11 and 12 are brought into contact with the inner surface of the lid body 5. There is a case in which a corner portion at the tip is abutted and chipped. In addition, the frequency adjustment metal films 19 and 20 cannot sufficiently absorb the shock when they come into contact with the inner surface of the lid body 5.

Further, when the thickness t of the frequency adjusting metal films 19 and 20 exceeds 15 μm, the remaining frequency adjusting metal films 19 and 20 are applied to the metallic lid 5 with a slight impact from the outside. There is a risk of contact.

As described above, in order to reduce the length along the longitudinal direction of the frequency-adjusting metal films 19 and 20 to be removed by the laser beam irradiation, in the manufacturing method of this embodiment, the state of the quartz wafer is used. That is, the first in the electrode forming step of forming electrodes on the base of the tuning fork type vibrating piece and the plurality of arms extending from the base while the plurality of tuning fork type vibrating pieces are integrally connected to the crystal wafer. The target frequency is set higher than the conventional first target frequency.

FIG. 7 shows target frequencies of the electrode forming step, the weighting step of forming the frequency adjusting metal films 19 and 20, and the rough frequency adjustment (laser processing) step by laser beam irradiation in the manufacturing method of this embodiment. FIG. 8 is a diagram for explaining, and FIG. 8 is a diagram corresponding to FIG. 7 of a conventional example, in which the horizontal axis represents frequency and the vertical axis represents frequency.

In the manufacturing method of this embodiment, the electrodes are formed on the base of the tuning fork type vibrating piece and the plurality of arms extending from the base while the plurality of tuning fork type vibrating pieces are integrally connected to the crystal wafer. The first target frequency fo1 shown in FIG. 7 in the electrode forming step as one step is set to a frequency higher than the first target frequency fo1′ shown in FIG. 8 in the electrode forming step of the conventional example shown in FIG.

The second target frequency fo2 shown in FIG. 7 in the weighting step as the second step of forming the frequency adjusting metal films 19 and 20 on the tip portions 11a and 12a of the arm portions 11 and 12 of the tuning fork type crystal vibrating piece 3. Is the same as the second target frequency fo2 shown in FIG. 8 in the weighting process of the conventional example.

Therefore, the amount of the frequency adjusting metal films 19 and 20 formed in the weighting step of forming the frequency adjusting metal films 19 and 20 on the tip portions 11a and 12a of the arm portions 11 and 12 of the tuning fork type crystal vibrating piece 3 (weight The amount applied is larger than in the conventional example.

The third target frequency fo3 in the frequency coarse adjustment step by laser beam irradiation as the third step after the weighting step is the above-mentioned nominal frequency 32.768 kHz, and the frequency rough adjustment step by laser beam irradiation in the conventional example. Is the same as the third target frequency fo3 shown in FIG.

Therefore, the removal amount of the frequency adjusting metal films 19 and 20 in the coarse frequency adjusting step by irradiation of the laser beam is substantially the same as that of the conventional example.

A large number of tuning fork type crystal vibrating pieces 3 in a crystal wafer state whose frequency is roughly adjusted by laser beam irradiation are broken from the crystal wafer and separated into individual tuning fork type crystal vibrating pieces 3, and as a fourth step, The metal bumps 8 of the tuning fork type crystal vibrating piece 3 are bonded to the electrode pads 7 of the base 4 of the package 2, housed in the base 2, and sealed with the lid 5.

In the manufacturing method of this embodiment, the second target with respect to the absolute value |fo1-fo2| of the frequency difference between the first target frequency fo1 of the tuning fork type resonator element in the electrode forming step and the second target frequency fo2 in the weighting step. The ratio (|fo2-fo3|/|fo1-fo2|) of the absolute value |fo2-fo3| of the frequency difference between the frequency fo2 and the third target frequency fo3 in the rough adjustment step is 0.5 or less, that is, ,
(|fo2-fo3|/|fo1-fo2|)≦0.5
In the manufacturing method of this embodiment, this ratio (|fo2-fo3|/|fo1-fo2|) is set to, for example, about 0.4.

By doing so, the frequency adjusting metal films 19 and 20 removed in the rough adjusting process with respect to the amount of the frequency adjusting metal films 19 and 20 formed at the ends of the arm portions 11 and 12 in the weighting process. It is possible to reduce the ratio of the removal amount of P compared to the conventional example.

As a result, the frequency adjusting metal films 19 and 20 after the rough adjusting step can be left in excess of half along the longitudinal direction.

Therefore, when the arm portions 11 and 12 of the tuning-fork type crystal vibrating piece 3 are bent toward the lid body 5 by an impact from the outside, the remaining frequency-adjusting metal films 19 and 20 are removed from the lid body 5. It is possible to prevent the tips of the wide tip portions 11a, 12a of the respective arm portions 11, 12 from coming into contact with the inner surface and coming into contact with the inner surface of the lid body 5 so as to prevent the corner portions from being chipped.

In the above embodiment, the frequency was adjusted by irradiating the laser beam, but other energy beams such as an ion beam other than the laser beam may be used.

[Embodiment 2]
In the above-described embodiment, as described with reference to FIG. 6, when the cantilever-supported tuning-fork type crystal vibrating piece 3 is bent by the impact from the outside, it is in the middle of reaching the tips of the arm portions 11 and 12. The abutting portions 11 b and 12 b come into contact with the pillow portion 9 provided on the bottom surface of the base 4 so that the tips of the wide tip portions 11 a and 12 a of the arm portions 11 and 12 come into contact with the bottom surface of the base 4. So that the corners are not chipped.

However, thin arm tip electrodes 25 and 24 are formed on the contact portions 11b and 12b of the arm portions 11 and 12 that are in contact with the pillow portion 9 on the bottom surface of the base 4, and the inventors of the present invention have been keenly aware of this. As a result of research, it was found that the arm tip electrodes 25 and 24 of the contact portions 11b and 12b of the arm portions 11 and 12 that contact the pillow portion 9 may be partially scraped, and the positive side fluctuation of the frequency may occur. I found it.

Therefore, in this embodiment, as described above, on the other main surface side facing the bottom surface of the base 4, as shown in FIG. 9, the free end portions of the first arm portion 11 and the second arm portion 12 are formed. The tip electrodes 11 and 12a having a certain width are not formed with the arm tip electrodes 24 and 25 except for a part on the side of the base portion 10 and are defined as the electrodeless regions 21 and 21 in which the quartz substrate is exposed.

FIG. 10 is a schematic cross-sectional view corresponding to FIG. 6 showing the vicinity of the tip of the tuning-fork type crystal vibrating piece 3 stored in the package 2. In FIG. 10, of the two arm portions 11 and 12, the tip portion 11a of the first arm portion 11 is representatively shown, but the tip portion 12a of the second arm portion 12 is also the same.

The electrodeless regions 21, 21 provided on the other main surface side of the tip portions 11a, 12a of the first and second arm portions 11, 12 are cantilever-supported tuning fork-type crystal vibrating pieces 3 by an external impact. When it bends, it includes at least the contact portions 11b and 12b of the first and second arm portions 11 and 12 that contact the pillow portion 9 and extends to the tips of the first and second arm portions 11 and 12. ing.

As described above, the contact portions 11b and 12b of the first and second arm portions 11 and 12 that contact the pillow portion 9 on the bottom surface of the base 4 are the electrodeless regions 21 and 21 in which the arm tip electrodes are not formed. Since the arm tip electrode is not scraped by the contact with the pillow portion 9, it is possible to suppress the fluctuation of the frequency toward the plus side due to the impact from the outside.

According to this embodiment, the arms 11 and 12 of the tuning-fork type crystal vibrating piece 3 are deflected toward the lid 5 side opposite to the base 4 on which the pillow 9 is projected by the impact from the outside. In this case, the remaining frequency adjusting metal films 19 and 20 come into contact with the inner surface of the lid 5 to prevent the tips of the arms 11 and 12 from coming into contact with the inner surface of the lid 5 and being damaged. Frequency fluctuation can be suppressed.

Further, due to an impact from the outside, the arm portions 11 and 12 of the tuning fork type crystal vibrating piece 3 are bent toward the base 4 side, and the contact portions 11b and 12b of the arm portions 11 and 12 are moved to the bottom surface of the base 4. Even if it abuts on the pillow part 9, the arm tip electrode will not be scraped and the frequency will not change.

As described above, due to the impact from the outside, the arm portions 11 and 12 of the tuning-fork type crystal vibrating piece 3 are caused to change in frequency due to bending toward the lid 5 side, and due to bending toward the base 4 side. It is possible to suppress any of the frequency fluctuations, and it is possible to obtain a tuning-fork type crystal resonator having good impact resistance.

In the above embodiment, the electrodeless region 21 includes not only the contact portions 11b and 12b where the first and second arm portions 11 and 12 contact the pillow portion 9, but also the first and second arm portions 11 and 12. Although it is formed to extend to the tip, only the contact portions 11b and 12b may be the electrodeless region.

In the above-described embodiment, the first and second arm portions 11 and 12 include at least contact portions 11b and 12b that are in contact with the pillow portion 9 when the first and second arm portions 11 and 12 bend toward the bottom surface of the base 4. Although the regions are the electrodeless regions 21 and 21 in which the arm tip electrodes are not formed, they may be configured as follows in still another embodiment of the present invention.

11 is a view corresponding to FIG. 4 of another embodiment of the present invention, and FIG. 12 is a schematic cross-sectional view corresponding to FIG. 6 of the embodiment of FIG.

In this embodiment, the arm tip electrodes 25 and 24 are formed over the entire circumference of the tip end portions 11a and 12a of the first and second arm portions 11 and 12, respectively. In addition, when the first and second arm portions 11 and 12 are bent toward the bottom surface side of the base 4 by the impact from the outside on the other main surface side facing the bottom surface of the base 4, the pillow portion 9 is Metal films 22 and 22 are formed in the abutting regions as buffer portions that buffer the impact at the time of abutting.

The metal film 22 has a thickness of 1 μm or more, for example, 10 μm in this embodiment so that a buffering effect can be obtained. Like the metal bump 8, the metal film 22 is made of, for example, gold, and a method such as an electrolytic plating method is used. By plating. Therefore, the metal film 22 can be formed simultaneously with the metal bump 8.

The metal film 22 is provided in a region that comes into contact with the pillow portion 9 when the first and second arm portions 11 and 12 are bent toward the bottom surface side of the base 4 due to an impact from the outside. In this embodiment, the metal film 22 is provided at the center position in the width direction of the wide tip portions 11a and 12a of the first and second arm portions 11 and 12, and is provided on the base portion 10 side, and is substantially planar view. It is circular.

In this way, in the regions of the first and second arm portions 11 and 12 that are in contact with the pillow portion 9 on the bottom surface of the base 4, the metal films 22 and 22 that buffer the impact due to the contact with the pillow portion 9 are 1 μm. Since the tuning fork crystal vibrating piece 3 is bent by an external impact, the metal films 22 and 22 of the arms 11 and 12 are formed on the bottom surface of the base 4 because they are formed by plating with the above thickness. Even if the metal films 22 and 22 come into contact with the portion 9, the metal films 22 and 22 are not easily peeled off, the impact of the contact is sufficiently buffered by the metal films 22 and 22, and the arm tip electrode 25 is not scraped off. It is possible to suppress the fluctuation of the frequency toward the positive side due to the impact. Further, as shown in the schematic cross-sectional view of FIG. 12, since the metal film 22 on the other main surface side of the tuning fork type quartz vibrating piece 3 is formed at the contact portion other than the tip of the arm portion. Even if the tip side of the arm portion of the frequency adjusting metal film is shaved by the irradiation of the laser beam, the metal film 22 is not reduced. As a result, the impact of contact between the tuning-fork type crystal vibrating piece 3 and the pillow portion can be buffered by the metal film 22, and the tip of each arm portion and the inner surface of the lid body can be contacted by the remaining metal film for frequency adjustment. Can also be prevented.

The metal film 22 as the buffer portion is not limited to one place, but may be provided at a plurality of places, for example, two places as shown in FIG.

Further, the metal film 22 is not limited to a circular shape in plan view, and may have another shape, for example, as shown in FIG. 13B, along the width direction of the tip portions 11a, 12a of the arm portions 11, 12. It may be formed in a rectangular shape in plan view.

In this embodiment, the arm tip electrodes 24 and 25 are formed in the portion where the buffer metal film 22 is formed. However, as another embodiment of the present invention, the periphery of the buffer metal film 22 is provided. It is also possible to form an electrodeless region in which the quartz substrate is exposed without forming the arm tip electrode in the region.

In each of the above-described embodiments, the joint portion 13 forming a part of the base portion 10 extends in the direction opposite to the extending direction of the first and second arm portions 11 and 12, and extends in the direction orthogonal to the extending direction. Although extending to one side (right side in FIG. 3 ), the joint portion 13 is formed in both the orthogonal directions (left side and right side in FIG. 14) as shown in the outline view of the tuning fork type crystal vibrating piece 3 in FIG. 14. 15) may be symmetrical to each other, or as shown in FIG. 15, it may extend in both of the orthogonal directions (left and right in FIG. 15) and further includes first, second It may have a bilaterally symmetrical shape extending in parallel to the extending direction of the arm portions 11 and 12, or, as shown in FIG. 16, from between the first and second arm portions 11 and 12, The shape may extend in the same direction as the extending direction of the second arm portions 11 and 12. In the tuning-fork type crystal vibrating piece 3 of each of these shapes, the two metal bumps 8 and 8 which are the bonding portions to be bonded to the electrode pads 7 and 7 of the base 4 have bonding portions as shown in FIGS. 14 to 16. It can be near the above-mentioned extended end of 13. In addition, the joining portion 13 may not be formed with a portion extending in a direction orthogonal to the extending direction or a portion extending in the same direction as the extending direction.

In each of the above-described embodiments, the description was made by applying the tuning-fork type quartz vibrating piece, but the present invention is not limited to this, and a piezoelectric material other than quartz may be used.

1 Tuning Fork Crystal Resonator 2 Package 3 Tuning Fork Crystal Resonator 4 Base 5 Lid 7 Electrode Pad 8 Metal Bump 9 Pillow 10 Base 11 First Arm 12 Second Arm 13 Joint 15 First Excitation Electrode 16th 2 Excitation electrode 17,18 Extraction electrode 19,20 Frequency adjustment metal film 21 Electrode-free area 22 Metal film (buffer part)
24,25 Arm tip electrode 26 Crystal

Claims (1)

A first step of forming electrodes on a base portion of the tuning fork type vibrating piece and a plurality of arm portions extending from the base portion while the plurality of tuning fork type vibrating pieces are integrally connected to the wafer; A second step of forming a frequency adjusting metal film on an end portion of one main surface of the front and back main surfaces in the extending direction, and a frequency by removing a part of the frequency adjusting metal film formed on the end portion. And a fourth step of accommodating each tuning fork type vibrating piece divided into individual tuning fork type vibrating pieces in the housing portion of the package body and sealing the opening of the package body with the lid. A method of manufacturing a tuning fork type vibrator, comprising:
The extension-direction end on which the frequency-adjusting metal film is formed in the second step is a wide end that is wide in the width direction orthogonal to the extension direction,
In the fourth step, in each tuning fork type resonator element, the base portion is joined to the electrode of the storage portion of the package body so that the one main surface faces the lid body.
Of the second target frequency and the third target frequency in the third step with respect to the absolute value of the difference in frequency between the first target frequency of the tuning fork type vibrating element in the first step and the second target frequency in the second step. The ratio of the absolute value of the frequency difference is 0.5 or less,
In the second step, the frequency adjusting metal film is formed with a thickness of 9 μm or more and 15 μm or less,
In the third step, the frequency adjusting metal film formed on the wide end portion of the arm portion in the extending direction is provided with the frequency adjusting metal film from the tip of the wide end portion along the extending direction. Toward the side, over a length of half or less of the length of the frequency adjusting metal film along the extending direction, to remove the base of the tuning fork type resonator element is exposed ,
The thickness of the frequency adjusting metal film formed in the second step is t (μm), and the distance from the inner surface of the lid to the portion of the arm where the frequency adjusting metal film is not formed. Is H (μm), t/H is
0.25≦t/H≦0.43
A method of manufacturing a tuning fork type vibrator, characterized in that

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