JP2009200648A - Frequency adjusting method for piezoelectric vibration device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a frequency adjusting method for a piezoelectric vibration device, capable of securing a sufficient adjustment amount even in a compact piezoelectric vibration chip and efficiently adjusting a frequency. <P>SOLUTION: A frequency adjustment step includes: a coarse adjustment step of thinning a large part or the entire area of a metal film 4 for adjustment formed on the main surface side of the arm part 2 of a tuning fork type piezoelectric vibration chip 1 and coarsely adjusting the frequency; and a fine adjustment step of finely adjusting the frequency by further thinning or removing part or the entire area of the area thinned in the coarse adjustment step. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a frequency adjustment method for a piezoelectric vibration device used in an electronic apparatus or the like.

  As shown in FIG. 9, a tuning fork crystal resonator widely used as a clock source for a timepiece or the like includes a base 3 and a pair of vibrating arms 2 extending in parallel in one direction from one end of the base. 2 (hereinafter abbreviated as an arm) and a base of a tuning-fork type crystal vibrating piece 1 (hereinafter abbreviated as a vibrating piece) is placed inside a box-shaped housing (not shown) with an upper portion interposed via a bonding material. In general, a surface mounting structure in which the opening is hermetically sealed with a flat lid (not shown) is generally used. In addition, the said arm part has two main surfaces of the front and back of an arm part, and two side surfaces of the inner side of an arm part, and an outer side.

  Among the manufacturing processes of the tuning fork type crystal resonator, there is a process called a frequency adjustment process. In the frequency adjustment step, in order to shift the frequency of the resonator element within a predetermined frequency range, the adjustment metal film formed on the arm tip region is irradiated with a laser beam or the like to adjust the frequency of the adjustment metal film. This is a process of reducing the mass. The oscillation frequency of the tuning-fork type crystal vibrating piece increases by reducing the mass of the adjustment metal film, but also in the adjustment metal film, a tip portion and a portion separated from the tip portion in the root direction of the arm portion And the frequency change amount (sensitivity) with respect to mass reduction is different. That is, the sensitivity is higher at the tip portion (for the same mass, the tip portion has a larger amount of frequency change than the portion separated from the tip portion). Therefore, as shown in FIG. 9, the adjustment metal film is divided into two regions in the arm extension direction, and the region closer to the arm tip is the coarse adjustment region (41), which is farther from the arm tip. The area is a fine adjustment area (42). Such a configuration of the adjustment metal film is disclosed in, for example, Patent Document 1.

JP-A-11-195952

  A case where the adjustment metal film is reduced (laser trimming) using a laser beam will be described with reference to FIG. First, a laser beam is irradiated onto the coarse adjustment region from above one main surface of the arm portion, and in one direction (in a direction perpendicular to the paper surface in FIG. 10) in a direction parallel to the arm width (a direction perpendicular to the arm portion extending direction). , Scanning from the back to the front). The laser beam is emitted while moving the scanning position in the direction from the tip of the arm portion toward the base of the arm portion within the region of the adjustment metal film. At this time, the laser beam is scanned until the target frequency range in the coarse adjustment is reached, but even after the completion of the coarse adjustment, not all of the metal film in the coarse adjustment region is necessarily reduced. Only the area may be reduced and other areas may remain. Similarly, even in the fine adjustment area, even after the fine adjustment is completed, a part of the fine adjustment area may remain. FIG. 11 shows this state.

  In recent years, with the progress of miniaturization of tuning-fork type crystal vibrating pieces, it has become difficult to ensure a sufficient adjustment region (adjustment amount) just by reducing the mass of the adjustment metal film with a laser beam as described above. After laser trimming, a metal film is further formed (thickened) on the adjustment metal film by vacuum deposition, and a laser beam is irradiated to the thickened metal film. It is necessary to repeat operations such as mass reduction.

  As described above, repeated film formation by laser trimming and vapor deposition leads to deterioration of production efficiency, and when a laser beam is irradiated to a thick metal film, the mass of the metal to be reduced increases. It becomes difficult to perform fine adjustment (small amount reduction).

  This invention is made | formed in view of this point, and it aims at providing the frequency adjustment method of the piezoelectric vibration device which can respond to size reduction and can perform frequency adjustment efficiently.

  In order to achieve the above object, the invention of claim 1 adjusts the frequency of the piezoelectric vibrating device by adjusting the frequency by reducing the mass of the adjusting metal film formed in the arm tip end region of the tuning fork type piezoelectric vibrating piece. A rough adjustment step of thinning most or all of the adjustment metal film formed on the main surface side of the arm portion to perform a rough adjustment of the frequency, and a thin wall in the rough adjustment step Since the frequency adjustment method of the piezoelectric vibrating device includes a fine adjustment step of finely adjusting the frequency by further thinning or removing a part or all of the converted region, the frequency adjustment region, that is, the arm The frequency adjustment can be performed by effectively utilizing the region where the adjustment metal film on the main surface side of the portion is formed. This is because, in the present invention, the coarse adjustment region is partitioned and not limited as in the prior art, and therefore adjustment (reduction of the metal film) can be performed using the region including the conventional fine adjustment region. It is. Therefore, it is not necessary to form a metal film again after reducing the mass of the adjustment metal film in order to secure the adjustment amount, and the production efficiency can be improved.

  In addition, according to the frequency adjustment method of the present invention, a sufficient amount of adjustment can be made because the adjustment metal film formed on the main surface side of the arm part is thinned most or all of the region to perform rough adjustment of the frequency. (Reduction amount of metal film) can be secured. Therefore, it is not necessary to form a film again after reducing the mass of the adjustment metal film as in the prior art, and the adjustment metal film is not thickened. Fine adjustment is performed by further thinning or removing part or all of the thinned region, so that a small amount of metal film can be reduced, and more accurate and efficient frequency adjustment is performed. It becomes possible.

  Furthermore, according to the frequency adjustment method of the present invention, after the coarse adjustment step, depending on the adjustment amount up to the target frequency range, a part or all of the region thinned in the coarse adjustment step is thinned. Fine adjustment can be performed by utilizing the thinned region of the conventional rough adjustment region (region near the tip of the arm). For example, by reducing or removing the thinned area of the adjustment metal film near the tip of the arm with good frequency change (sensitivity) for mass reduction, the target can be reduced with a small amount of reduction. Since the frequency range can be reached, the efficiency of frequency adjustment is improved.

  In order to achieve the above object, according to a second aspect of the present invention, there is provided a frequency tuning method for a tuning fork type piezoelectric vibration device, wherein the rough tuning step and the fine tuning step are performed using a laser. Therefore, when a part or all of the region thinned in the rough adjustment process is further thinned, a small amount of metal film can be reduced with high efficiency.

  In addition, removal of part or all of the region thinned in the rough adjustment step can be efficiently performed using a laser. This is because the adjustment metal film can be adjusted in a short time because it does not require many steps as compared with the case where the adjustment metal film is thinned or removed by means other than laser, and efficient adjustment is possible.

  In order to achieve the above object, the tuning fork type piezoelectric vibration device according to the invention of claim 3 is characterized in that the adjustment metal film is irradiated with a laser beam while suppressing the output, and is thinned or removed. Therefore, the thinned region can be easily formed.

  In other words, when forming a thin region (residue part), the laser beam output is suppressed at an energy level that can be reduced by the adjustment metal film, and the adjustment metal film on one main surface side of the arm part is irradiated. Thus, a thin region (residue portion) can be formed without completely removing the adjustment metal film. Further, when the metal film for adjustment is completely removed, it can also be dealt with by reducing the output suppression amount of the laser beam.

  In order to achieve the above object, according to the invention of claim 4, in the coarse adjustment step, the output is varied and the adjustment metal film is irradiated with a laser beam to reduce the thickness, thereby reducing the thickness of the region. In this method, the step is formed in the tuning fork type piezoelectric vibration device. In other words, by adjusting (suppressing) the output of the laser beam at the energy level that can be reduced by the adjustment metal film, the adjustment metal film is irradiated to the adjustment metal film on one main surface side of the arm portion, thereby adjusting the metal film A step (thickness difference) can be formed in the thinned region.

  As described above, since a difference in height occurs in the thinned region by forming the step, depending on the amount of adjustment up to the target frequency range, the thinned region of the adjustment metal film is further increased. Thinning or removal can be performed by selecting a region. That is, after the coarse adjustment step, if the amount of adjustment up to the target frequency range is large, the high altitude region in the thinned region (thick region in the thinned region) may be further thinned or removed, On the other hand, when the adjustment amount to the target frequency range is small, the lowland area in the thinned area (thinned area in the thinned area) may be further thinned or removed. At this time, if the low altitude region is formed on the side closer to the arm tip and the high altitude region is formed on the side far from the arm tip, the high adjustment sensitivity side is thin and the low adjustment sensitivity side is thick. Is preferable.

  As described above, according to the present invention, it is possible to provide a method for adjusting the frequency of a piezoelectric vibrating device capable of efficiently adjusting the frequency corresponding to downsizing.

-First embodiment-
Hereinafter, the tuning fork type crystal resonator will be described as an example, and the first embodiment according to the present invention will be described focusing on the frequency adjustment step. In the tuning fork type crystal resonator used in the present embodiment, a tuning fork type crystal resonator element is bonded via a metal bump on a mounting electrode inside a housing having an upper opening, and the opening is sealed with a sealing material. It has the structure joined by the plate-shaped cover body. Here, in this embodiment, the nominal frequency of the tuning fork type crystal resonator is 32.768 kHz. The nominal frequency is an example and can be applied to other frequencies.

  The above-described casing (not shown) is a container made of ceramic, and is formed by firing. The casing has a concave shape in cross section with an upper opening, and a step portion for mounting a tuning fork type crystal vibrating piece is formed inside the casing. A pair of mounting electrodes is formed on the upper surface of the step portion by a printing technique. The mounting electrode is subjected to gold plating on the surface after printing and baking tungsten. The mounting electrode is electrically connected to an external terminal (not shown) formed on the bottom surface (back surface) of the housing via a wiring conductor (not shown) formed inside the housing. A bank-like straight solid is formed in an annular shape around the opening of the housing, and a metal film composed of a plurality of layers is formed on the upper surface of the straight solid. The metal film is composed of three layers, and is laminated from the bottom in the order of tungsten, nickel, and gold. Tungsten is integrally formed during ceramic firing by metallization technology, and the nickel and gold layers are formed by plating technology. Note that molybdenum may be used for the tungsten layer.

  FIG. 1 is a plan view of an assembly of tuning-fork type crystal vibrating pieces showing a first embodiment of the present invention. In FIG. 1, the description of various electrodes formed on the arm portion and the base portion of each tuning-fork type crystal vibrating piece is omitted. The tuning fork type crystal vibrating piece 1 includes a pair of arm portions 2 and 2 and a base portion 3, and a large number of tuning fork type crystal vibrating pieces from a single crystal wafer 11 (hereinafter abbreviated as a wafer) having a rectangular shape in plan view. 1, 1... (Hereinafter abbreviated as vibration piece) are formed. In the present embodiment, thousands of vibrating pieces are collectively formed from one wafer. The number of vibrating pieces is only an example, and hundreds to thousands of vibrating pieces can be collectively formed from one wafer.

  The outer shape of the resonator element is collectively formed by etching using a resist or a metal film as a mask, using a photolithography technique. Although not shown in FIG. 1, various electrodes (metal films) are formed in a predetermined shape on the arms 2 and 2 and the base 3 of the resonator element 1 using vacuum deposition and photolithography. Specifically, among the various electrodes, each of the electrodes formed on the arm portions 2 and 2 is composed of a main surface electrode (front surface and back surface) and a side electrode (inner surface and outer surface), It has a configuration in which chromium (Cr) is used as a base and gold (Au) is laminated thereon. On the other hand, a pair of bonding electrodes made of gold are formed on both the front and back surfaces of the base 3 simultaneously with the formation of the electrodes of the arm portions 2 and 2. Therefore, the bonding electrode also has a structure in which chromium is used as a base layer and gold is formed thereon.

  FIG. 2 is a plan view of the resonator element according to the first embodiment of the invention. In FIG. 2, the various electrodes formed on the arm and base are not shown. A metal film is formed on the tip region of each of the arm portions 2 and 2 of each vibration piece in the same layer configuration as the above-described electrode. Further, adjustment metal films 4 and 4 for adjusting the frequency are provided around the metal film. The adjustment metal films 4 and 4 include an outer surface metal film (not shown) on the outer surface of the arm portion, a front main surface metal film (not shown) on the front main surface of the arm portion, and the back main surface. The back main surface metal film (not shown), and the inner side metal film (not shown) on the inner side surface. In the present embodiment, gold is used for the adjustment metal film, and the film is formed by an electrolytic plating method. The adjustment metal film may be formed using a vacuum deposition method in addition to the electrolytic plating method.

  The frequency of the large number of vibrating pieces 1, 1... In the wafer 11 is lower than the frequency before the various electrodes are added by adding various electrodes to each vibrating piece. Then, the adjustment metal films 4 and 4 are formed in the arm tip region, whereby the frequency is further lowered. In the present invention, the adjustment metal films 4 and 4 are not partitioned into a coarse adjustment region and a fine adjustment region. That is, the entire area of the adjustment metal film on the arm main surface is the main adjustment target range. Hereinafter, the frequency adjustment process will be described with reference to the drawings.

  First, the frequency of a large number of vibrating pieces 1, 1... On the wafer 11 is measured, and a necessary adjustment amount (frequency change amount) up to a target frequency range (rough adjustment frequency standard) in rough adjustment is obtained. Then, a laser beam is applied to most or all of the adjustment metal film 4 on one main surface (front main surface) near the tips of the arms 2 and 2, and the mass of the adjustment metal film (Coarse adjustment process). The mass reduction of the adjustment metal film by the laser beam is performed by scanning the laser beam linearly in one direction (from left to right) with respect to the adjustment metal film as shown in FIG. This is performed while moving the scanning position in a direction away from the front end side. In this embodiment, the laser beam is irradiated after the frequency is measured, but the frequency measurement and the laser beam irradiation may be performed simultaneously.

  In this embodiment, the output at the time of laser beam irradiation is suppressed as compared with the output of the laser beam at the time of conventional frequency adjustment. Specifically, in this embodiment, irradiation is performed with an output of about 90% of the conventional output. By suppressing the output of the laser beam in this way, the adjustment metal film on the front main surface side can be left (thinned) without being completely reduced (removed). That is, in this embodiment, the laser beam output suppression is aimed at forming a thin region (hereinafter referred to as a residue portion) of the adjustment metal film, and is limited to the above-described conventional output ratio (90%). It is not a thing. That is, it is only necessary to set the laser output so that the residue portion can be formed. In this embodiment, the laser beam is irradiated from the vertical direction to the quartz crystal wafer 11 installed in a horizontal state. Note that the present invention is not limited to the laser irradiation from the above direction, and the irradiation direction of the laser beam is not limited as long as the residue portion of the adjustment metal film can be formed. Furthermore, although a laser beam is used in the present embodiment, mass reduction means other than the laser beam may be used.

  The state after the aforementioned rough adjustment process is shown in FIGS. 3 is a plan view showing the arm tip region after rough adjustment, and FIG. 4 is a cross-sectional view taken along line BB in FIG. For convenience of explanation, FIG. 3 is a plan view of one arm portion tip region of the pair of arm portions 2 and 2. As shown in FIG. 3, a residue portion 5 is formed on the adjustment metal film 4 on the arm main surface by irradiation with a laser beam whose output is suppressed. In the present embodiment, the residue portion 5 is formed so as to occupy most of the region of the adjustment metal film on the main surface of the arm portion. In addition, the formation region of the residue portion may extend not only to the majority of the adjustment metal film on the main surface of the arm portion but also to the entire region.

  In the present embodiment, scanning of the laser beam is started from the tip of the arm portion in the region of the adjustment metal film 4 on the main surface of the arm portion, and from the peripheral portion farthest from the tip of the arm portion of the adjustment metal film. The laser is scanned over the previous position. Therefore, as shown in FIG. 4, in the sectional view, a part of the adjustment metal film 4 is thinned (residue portion 5) in a concave shape. At this time, a part of the laser beam irradiated to the front main surface metal film from above the front main surface of the arm portion passes through the residue portion 5 and passes through the inside of the crystal vibrating piece 2, and then the back main surface In some cases, the mass of the back main surface metal film may be reduced by reaching the metal film. In addition, irregularities may be formed on the surface of the residue portion depending on the laser beam irradiation conditions. Since the laser output is suppressed in advance in this way, even if the majority of the metal film for adjustment on the arm main surface side is thinned, the mass of the metal film to be reduced does not become excessive and deviates from the frequency standard. Hard to do. Therefore, compared with the conventional rough frequency adjustment method, the formation region of the adjustment metal film can be effectively used. The irradiation start position of the laser beam may be a position separated from the tip of the arm within the region of the adjustment metal film 4 on the main surface of the arm.

  In addition, since the frequency adjustment method of the present invention performs rough frequency adjustment by thinning most of the metal film for adjustment formed on the main surface side of the arm portion, a sufficient adjustment amount (a reduction amount of the metal film) ) Can be secured. Therefore, it is not necessary to form a film again after reducing the mass of the adjustment metal film as in the prior art, and the adjustment metal film is not thickened more than necessary. Thereby, the usage-amount of a metal substance can be reduced.

  When the rough adjustment step is completed, as shown in FIG. 4, a partial adjustment of the frequency is performed by irradiating a partial region of the residue portion 5 with a laser beam and further reducing the thickness of the residue portion. (Fine adjustment process). FIG. 5 is a cross-sectional view showing the state after the fine adjustment process in FIG. 4, in which the residual portion of the region irradiated with the laser beam is removed, and the region of the region not irradiated with the laser beam in the fine adjustment step is shown. The residue part remains as it is. As described above, in the fine adjustment step according to the present invention, since a sufficient adjustment amount is ensured in the coarse adjustment step of the previous step, the frequency adjustment of the resonator element can be performed with a slight adjustment amount. In addition, it is possible to perform more efficient frequency adjustment by arbitrarily selecting a reduction region for the residue portion 5 according to a necessary adjustment amount up to the target frequency range (fine adjustment frequency standard). That is, the difference in the amount of change in frequency (sensitivity) due to the mass reduction of the metal film is used. For example, by irradiating a laser beam intensively on the residue part in the region near the tip of the arm part, the laser beam is irradiated on the residue part in the region separated from the arm part tip in the adjustment metal film on the main surface. Rather than this, a large frequency adjustment effect can be obtained with a small reduction amount. In the fine adjustment step, the laser beam may be irradiated not only on a partial region of the residue portion 5 but also on the entire region of the residue portion. Further, in the fine adjustment step, the metal film of the residue portion 5 may be completely removed as well as being thinned.

  According to the present invention, since the metal film for frequency adjustment in the arm tip region is partitioned as in the prior art and the adjustment region is not limited, the frequency coarse adjustment includes the conventional fine adjustment region. Can be used for adjustment (reduction of mass). Therefore, a process of forming a metal film again after reducing the mass of the adjustment metal film is not necessary to secure the adjustment amount, and the production efficiency can be improved.

  As described above, when the frequency adjustment for all the vibration pieces 1, 1... In the wafer 11 is completed, the wafer 11 is divided into pieces of vibration pieces 1, 1 after passing through a predetermined process. .

  In the divided vibrating piece 1, a pair of bonding electrodes formed on the base 3 of the vibrating piece is bonded to a pair of mounting electrodes inside the housing via metal bumps.

  After the piece of vibrating piece 1 is joined to the inside of the housing, a final fine adjustment of the frequency is performed. The final fine adjustment is performed by ion etching. The ion beam is applied to a wider area than the laser beam. That is, the laser beam is scanned linearly by continuous irradiation of dots, whereas the ion beam is irradiated in a planar shape with a certain area.

  At this time, for example, if the remaining (thin) area of the adjustment metal film 4 is large (the remaining area is large) even after the frequency fine adjustment step, it is suitable for final fine adjustment of the frequency by ion etching. When a part of the adjustment metal film is completely removed in the frequency fine adjustment process and there are many portions where the crystal base is exposed in the frequency adjustment target area, it remains (because there is no metal film in the crystal base area). In order to more efficiently reduce the mass of the metal film by irradiating the adjustment metal film with the ion beam, it is necessary to increase the output of the ion beam and irradiate the vibration piece. It becomes a state, and the variation in frequency will expand. However, if the remaining area of the adjustment metal film 4 is large (the remaining area is large) after the fine frequency adjustment process, a large amount of mass reduced by the ion beam can be secured. That is, a sufficient adjustment amount (a reduction amount of the metal film) can be obtained even when the ion beam output is reduced and irradiation can be prevented, so that the resonator element can be prevented from reaching a high temperature. Therefore, it is possible to suppress an increase in frequency variation, which is suitable for final fine adjustment of the frequency by ion etching.

  And after passing through a predetermined | prescribed process, it mounts so that the outer periphery of the flat cover body which consists of a metal may correspond with the upper surface of the solid body of a housing | casing substantially. In addition, a sealing material is formed in a circumferential shape on the joint surface of the lid body with the housing and the top surface of the solid body of the housing. Then, the lid and the casing are hermetically joined by irradiating the laser from above the lid and melting the sealing material. This completes the tuning fork crystal unit. In the present embodiment, metal bumps are used as the bonding material between the resonator element and the housing. However, in addition to the metal bumps, a paste-like conductive adhesive may be used.

-Second Embodiment-
A second embodiment of the present embodiment will be described with reference to FIG. FIG. 6 is a cross-sectional view of the distal end of the arm after the rough adjustment process showing the second embodiment of the present invention. For simplicity, only one arm 2 is displayed in the pair of arms 2 is doing. In FIG. 6, description of various electrodes formed on the tuning fork vibrating piece is omitted. Moreover, about the structure similar to 1st Embodiment, while attaching | subjecting the same number and omitting description, it has an effect similar to the above-mentioned embodiment. Hereinafter, a description will be given focusing on differences from the first embodiment.

  In this embodiment, the adjustment metal film is irradiated in a state where the laser output is suppressed in the coarse frequency adjustment step, but the output is not constant. That is, in the coarse adjustment process, the laser output is set in two stages within the output level at which the adjustment metal film 4 can be reduced. As a result, as shown in FIG. 6, the adjustment metal film 4 has a difference (step) in the formation depth of the residue portion in a cross-sectional view. That is, two regions S1 and S2 having different depths are formed in the thinned region, and a step (step 6) is formed at the boundary between the two regions. Since the region S2 is irradiated with the output further suppressed than the laser output to the region S1, the region S2 is thicker than the region S1. Note that the thickness of the region S2 is thicker than the residue formed in the coarse adjustment step of the first embodiment.

  After the above-described rough adjustment process, a laser beam is irradiated on the residue portion 5 formed on each vibration piece in the quartz wafer according to a necessary adjustment amount up to a predetermined frequency standard (fine adjustment frequency standard). Make fine adjustments. At this time, irradiation of the laser beam to the residual portion of each vibration piece is performed on either the region S1 or S2, or both regions S1 and S1, depending on the necessary adjustment amount up to the frequency standard of the vibration piece. Do it. In this way, the laser beam is irradiated, and the residue portion 5 is further thinned or removed to finely adjust the frequency.

  By forming regions with different thicknesses (steps 6) in the residue region as described above, a region for further thinning or removing the residue portion 5 is selected according to the necessary adjustment amount up to the target frequency range. Can be done. That is, after the rough adjustment process, when the adjustment amount to the target frequency range is large, the high altitude region S2 (thick region in the thinned region) in the thinned region may be further thinned or removed. On the contrary, when the adjustment amount up to the target frequency range is small, the lowland area S1 in the thinned area (thinned area in the thinned area) may be further thinned or removed. That is, as in the present embodiment, when the low altitude region S1 is formed on the side closer to the arm tip, and the high altitude region is formed on the side far from the arm tip, the side with low adjustment sensitivity becomes thick, and the degree of freedom of mass reduction by the laser beam is increased. And more efficient frequency adjustment can be performed.

  As a modification of the second embodiment, by changing the output of the laser, as shown in FIG. 7, the thickness of the residue portion 5 can be gradually reduced as it approaches the tip of the arm portion. By forming the residue portion in this way, it is possible to finely adjust the frequency in small increments.

  As yet another modification, as shown in FIG. 8, a plurality of thin regions and regions thicker than the thin regions may be formed in the residue region forming region. In this way, efficient fine adjustment of the frequency can be performed by forming the thick residue portion in the region including the center in the arm extending direction of the adjustment metal film. That is, since the position where the residue portion of the thick region is formed is unevenly distributed in the region including the center in the arm extension direction of the adjustment metal film, the position near the tip of the arm and the position away from the tip of the arm The intermediate adjustment sensitivity can be adjusted in small increments (mass reduction). In addition to the form as shown in FIG. 8, a form in which a plurality of thin regions and a plurality of thick regions are formed in combination in the region of the adjustment metal film may be used.

  In the embodiment of the present invention, a surface mount type tuning fork type crystal resonator is taken as an example, but in addition to a tuning fork type crystal resonator, an AT cut crystal resonator, a crystal filter, a crystal oscillator, and other electronic devices are used. This method can also be applied to the frequency adjustment method of the surface mount type piezoelectric vibration device.

  The present invention can be implemented in various other forms without departing from the spirit or main features thereof. Therefore, the above-described embodiment is merely an example in all respects and should not be interpreted in a limited manner. The scope of the present invention is indicated by the claims, and is not restricted by the text of the specification. Further, all modifications and changes belonging to the equivalent scope of the claims are within the scope of the present invention.

  It can be applied to mass production of piezoelectric vibration devices.

The top view of the aggregate | assembly of the tuning fork type | mold crystal vibrating piece which shows the 1st Embodiment of this invention. 1 is a plan view of a tuning-fork type crystal vibrating piece showing a first embodiment of the present invention. The enlarged plan view of the arm part front-end | tip after the rough adjustment process in the 1st Embodiment of this invention. Sectional drawing in the AA of FIG. Sectional drawing which shows the state after a fine adjustment process in FIG. Sectional drawing of the arm part front end after the rough adjustment process which shows the 2nd Embodiment of this invention. Sectional drawing of the arm part front end after the rough adjustment process which shows the modification of the 2nd Embodiment of this invention. Sectional drawing of the arm part front end after the rough adjustment process which shows the modification of the 2nd Embodiment of this invention. The top view of the tuning fork type crystal vibrating piece which shows an example of the past. Sectional drawing in the BB line of FIG. Sectional drawing which shows the state after frequency fine adjustment in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tuning fork type crystal vibrating piece 2 Arm part 3 Base part 4 Metal film for adjustment 5 Residue part 6 Step part

Claims (4)

A frequency adjustment method for a piezoelectric vibration device that performs frequency adjustment by reducing the mass of an adjustment metal film formed in an arm tip region of a tuning fork type piezoelectric vibration piece,
A rough adjustment step in which the adjustment metal film formed on the main surface side of the arm part is subjected to rough adjustment of the frequency by thinning most or all regions,
A method of adjusting a frequency of a piezoelectric vibration device, comprising: a fine adjustment step of finely adjusting a frequency by further thinning or removing a part or all of the thinned region in the rough adjustment step.   The method for adjusting a frequency of a piezoelectric vibration device according to claim 1, wherein the rough adjustment step and the fine adjustment step are performed using a laser.   3. The method of adjusting a frequency of a piezoelectric vibrating device according to claim 1, wherein the adjustment metal film is irradiated with a laser beam while suppressing an output to reduce or remove the thickness.   4. The coarse adjustment step, wherein the output is varied and the adjustment metal film is irradiated with a laser beam to reduce the thickness, and a step portion is formed in the reduced thickness region. Frequency adjustment method for piezoelectric vibration device of.

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