JP4618440B2 - Crystal resonator element and vibration device - Google Patents

Description

  The present invention relates to a vibrator having an electrostatic discharge (ESD) protection function, and more particularly to a crystal vibrating piece and a vibrating device that discharge static electricity into air through discharge protrusions.

  A crystal vibrating piece or a piezoelectric device using the crystal vibrating piece is widely used as a clock source of an electronic device such as an electronic timepiece, a computer, or a mobile phone, or for measuring an angular velocity. In recent years, the degree of integration of electronic components has increased, and accordingly, further downsizing of crystal vibrating pieces or piezoelectric devices has been required. Miniaturization of the quartz crystal resonator element or the piezoelectric device has also reduced the electrostatic resistance.

The quartz crystal resonator element or the piezoelectric device must prevent the device from being destroyed by static electricity stored in the human body. For this reason, the ESD test is an HBM (Human Body Model) test. In addition, to prevent the piezoelectric device from being destroyed by static electricity accumulated in the assembly device of the piezoelectric device,
MM (machine model) testing is being conducted. Recently, due to further miniaturization of quartz crystal resonator pieces or piezoelectric devices, rapid charge transfer has occurred when charges charged in the capacitance inherent to the device approach or come into contact with conductors having different potential potentials. (Charged device model) Tests are also being conducted.

The ESD withstand voltage of the crystal vibrating piece or the piezoelectric device is about 500 V, which is lower than that of other electronic components. For this reason, it is required to improve the ESD withstand voltage of the crystal vibrating piece or the piezoelectric device. In particular, with the miniaturization of a quartz crystal resonator element or a piezoelectric device, a pattern is often destroyed by electrostatic discharge in a thin electrode pattern.
JP 2001-235497 A

  An object of the present invention is to discharge an electrostatic charge into the air through discharge protrusions by electrostatic discharge reaction in order to avoid damage to a circuit having a narrow electrode pattern width of a crystal resonator element by electrostatic discharge reaction. The above requirements are satisfied by providing a quartz crystal resonator element having a discharge protection function.

A crystal resonator element according to a first aspect includes a crystal substrate, first and second metal layers disposed in a predetermined region on the surface of the crystal substrate, and the first metal layer formed on the first metal layer. A plurality of discharge protrusions formed from the layer to the second metal layer.
According to the above configuration, the charges are canceled out between the electrostatic charges collected at the plurality of discharge protrusions and the induced charges in the air. That is, the electrostatic charge of the quartz crystal vibrating piece causes an electrostatic discharge reaction through the particles in the atmosphere through the discharge protrusion. For this reason, it becomes a crystal vibrating piece that can pass the test sufficiently even in the HBM test, the MM test, or the CDM test. Further, even in a device in which a quartz crystal resonator element is actually used, the quartz crystal resonator element has electrostatic resistance.

The quartz crystal resonator element according to the second aspect has a tuning fork shape including an arm portion and a base portion, and the discharge protrusion is provided on the base portion.
According to the above configuration, the crystal vibrating piece is a tuning fork type crystal vibrating piece, and the base is formed on the crystal vibrating piece. Since there is a space in the base, if the discharge protrusion is formed in this part, the space can be effectively used.

In the quartz crystal resonator element according to the third aspect, the metal layer is a two-layer film in which an upper second metal film is formed on a lower first metal film, or a single layer film in which a third metal film is formed.
According to the above configuration, since the discharge protrusion can be formed of the same material as the vibrating electrode of the crystal vibrating piece, it is not necessary to increase the number of times of sputtering of the metal film, and the discharge protrusion is drawn on the mask when forming the electrode. Just enough.

In the photosensitive agent coating method according to the fourth aspect, the metal layer has a thickness of about 250 angstroms to 10,000 angstroms.
In the electrostatic discharge reaction, electric energy is released by the charge of the discharge protrusion and the induced charge in the air, and an electromigration phenomenon occurs, raising the temperature of the discharge protrusion. At this time, since the thickness of the metal layer is 250 to 10000 angstroms, the discharge protrusions are burned (sublimated).

In the quartz crystal resonator element according to the fifth aspect, the plurality of discharge protrusions are serrated.
If it is serrated, a plurality of discharge protrusions can be formed easily.

According to the quartz crystal resonator element of the sixth aspect, it is formed on the spiral metal film.
According to the above configuration, a plurality of discharge protrusions can be formed at a plurality of locations.

In the crystal resonator element according to the seventh aspect, the intervals between the plurality of discharge protrusions of the first metal layer and the second metal layer are different from each other.
According to the above configuration, normally, electrostatic discharge is first generated in the discharge protrusion having the narrowest interval where the electromigration phenomenon is likely to occur. FIG. 7 shows the discharge energy depending on the charging voltage of the human body. In order to destroy the crystal resonator element, the discharge energy is sufficient and a surge is generated many times. One discharge protrusion can withstand multiple surges, but the multiple discharges cause the tips of the discharge protrusions to deform in a direction in which the distance between the tips of the discharge protrusions increases. For this reason, after the tip of the discharge protrusion is deformed, an electromigration phenomenon occurs in the next discharge protrusion. Even the next discharge protrusion can withstand multiple surges. Thus, since a plurality of surges can be dealt with from a location where the distance between the plurality of discharge protrusions of the first metal layer and the second metal layer is narrow, a complete ESD protection function can be achieved.

In the quartz resonator element of the eighth aspect, the widest distance between the plurality of discharge protrusions of the first metal layer and the second metal layer is such that the first metal layer and the second metal other than the discharge protrusions are Narrower than the narrowest spacing of the layers.
According to the above configuration, electrostatic discharge is first generated in the discharge protrusion having the narrowest interval where the electromigration phenomenon is likely to occur. Even the narrowest part of the electrode pattern is wider than the interval between the places where the discharge protrusions are formed. For this reason, even if multiple surges occur, electrostatic discharge is generated at the discharge protrusion, and the electrode pattern or the like is not affected.

In the crystal resonator element according to the ninth aspect, the plurality of discharge protrusions are formed by photolithography and etching.
The crystal vibrating piece itself is several mm, and the narrow interval between the electrode patterns is about 0.02 mm. For this reason, the interval between the plurality of discharge protrusions of the first metal film and the second metal film is 0.015 mm or less. Even such fine processing is possible by photolithography and etching.

A vibrating device according to a tenth aspect includes the crystal vibrating piece according to any one of claims 1 to 9 and a package for vacuum-sealing the crystal vibrating piece.
As a vibration device, the HBM test, MM test, or CDM test can pass the test sufficiently.

According to the present invention, an electrostatic discharge reaction is caused between an electrostatic charge and an induced charge through particles in the atmosphere at a quartz crystal resonator element or a discharge protrusion in a piezoelectric device. For this reason, the ESD withstand voltage of the crystal vibrating piece or the piezoelectric device can be improved.
Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<Configuration of tuning fork type crystal vibrating piece 20>
FIG. 1A is a diagram showing an overall configuration of the tuning fork type crystal vibrating piece 20, and FIG. 1B is a BB cross-sectional view of one vibrating arm 21 of the tuning fork type crystal vibrating piece 20. The base material of the tuning fork type crystal vibrating piece 20 is formed of a crystal single crystal wafer 10 processed into a Z-cut. In order to obtain the required performance in a small size, as shown in FIG. 1A, a tuning fork type crystal vibrating piece 20 is divided into a bifurcated and parallel to a base 29 and upward from the base 29 in FIG. A pair of extending vibrating arms 21 is provided. Hereinafter, in the present embodiment, the tuning fork type crystal vibrating piece 20 including a pair of vibrating arms 21 will be described, but the crystal vibrating piece 20 including three or four vibrating arms 21 may be used.

  The tuning-fork type crystal vibrating piece 20 is a vibrating piece that transmits a signal at, for example, 32.768 KHz, and is an extremely small vibrating piece. The overall length is about 2.0 mm and the width is about 0.5 mm. Grooves 211 are formed on the front and back surfaces of the vibrating arm 21 of the tuning fork type crystal vibrating piece 20. Two groove portions 211 are formed on the surface of one vibrating arm 21, and two groove portions 211 are similarly formed on the back surface side of the vibrating arm 21. That is, four groove portions 211 are formed in the pair of vibrating arms 21. The depth of the groove 211 is about 35 to 45% of the thickness of the crystal single crystal wafer 10 and the groove 211 is present on the front and back surfaces. Therefore, as shown in FIG. It is formed in an H shape. The groove 211 is provided to suppress an increase in CI value.

  The base 29 of the tuning fork type crystal vibrating piece 20 is formed in a substantially plate shape as a whole. The length of the base 29 with respect to the vibrating arm 21 is about 36%. Two connecting portions 28 are provided on the base 29 of the tuning fork type crystal vibrating piece 20. The connecting portion 28 is a portion for connecting the crystal single crystal wafer 10 and the tuning fork type crystal vibrating piece 20 when the tuning fork shape shown in FIG. 1 is formed from the crystal single crystal wafer 10 by photolithography and wet etching.

  A first electrode pattern 23 and a second electrode pattern 25 are formed on the vibrating arm 21 and the base 29 of the tuning fork type crystal vibrating piece 20. Both the first electrode pattern 23 and the second electrode pattern 25 have a structure in which a gold (Au) layer of 100 angstroms to 5000 angstroms is formed on a chromium (Cr) layer of 150 angstroms to 5000 angstroms. That is, when the first layer and the second layer are combined, the thickness of the electrode pattern is 250 Å to 10000 Å. Further, a tungsten (W) layer, a nickel (Ni) layer, a nickel tungsten layer, or a titanium (Ti) layer may be used instead of the chromium (Cr) layer, and silver instead of the gold (Au) layer. An (Ag) layer may be used. In some cases, an aluminum (Al) layer, a copper (Cu) layer, or a silicon (Si) layer is used.

  As shown in FIG. 1A, a first base electrode 23 a and a second base electrode 25 a are formed on the base 29 of the tuning fork type crystal vibrating piece 20, and the first groove is formed on the groove 211 of the arm 21. An electrode 23d and a second groove electrode 25d are formed, respectively. Further, as shown in FIG. 1B, second side electrodes 25c are formed on both side surfaces of the left arm portion 21 in FIG. First side electrodes 23c are formed on both side surfaces of the right arm 21 (not shown).

  The first side electrode 23c and the second side electrode 25c are connected to the first base electrode 23a and the second base electrode 25a via the first connection electrode 23b and the second connection electrode 25b. The first electrode pattern 23 and the second electrode pattern 25 to be mirrored are also formed on the back surface of the tuning fork type crystal vibrating piece 20. Since the tuning fork type crystal vibrating piece 20 is small, the gap WA between the side electrode 25c and the groove electrode 23d is about 0.02 mm as shown in FIG. For this reason, the side electrode 25c and the groove electrode 23d are short-circuited or defective products are likely to appear in the ESD test. Of these, the first discharge electrode 23 s and the second discharge electrode 25 s are provided on the base 29 of the tuning-fork type crystal vibrating piece 20 so that the ESD test can be endured many times and is not easily damaged by static electricity. Is formed.

<Electrostatic discharge electrode pattern>
FIG. 2 is an enlarged view of the base 29 of the tuning-fork type crystal vibrating piece 20 and shows an electrode pattern for electrostatic discharge according to the first embodiment.
FIG. 3A shows an electrode pattern for electrostatic discharge according to the second embodiment, and FIG. 3B shows an electrode pattern for electrostatic discharge according to the third embodiment.
4A shows an electrode pattern for electrostatic discharge according to the fourth embodiment, and FIG. 4B shows an electrode pattern for electrostatic discharge according to the fifth embodiment.

<< Embodiment 1 >>
A spiral first discharge electrode 23s is formed from the first base electrode 23a, and a spiral second discharge electrode 25s is formed from the second base electrode 25a. The first discharge electrode 23s gradually becomes a thin electrode and forms a first protrusion 231-N. The second discharge electrode 25s also gradually becomes a thin electrode to form the second protrusion 251-M. The space between the first protrusion 231 -N and the second protrusion 251 -M is the narrowest distance between the first electrode pattern 23 and the second electrode pattern 25, and is set to 0.008 mm, for example.

  A plurality of discharge protrusions 231-i extending to the second discharge electrode 25 s side are formed midway from the base of the first discharge electrode 23 s to the first protrusion 231 -N. A plurality of second protrusions 251-i extending toward the second discharge electrode 23 s are formed in the middle from the root of the second discharge electrode 25 s to the second protrusion 251 -M. N and M protrusions are respectively formed. The plurality of first protrusions 231-i are spaced from the widest width WC between the second discharge electrodes 25 s to the narrowest distance between the first protrusion 231 -N and the second protrusion 251 -M. It has changed. Also, the plurality of second protrusions 251-i is from the widest width WC between the first discharge electrode 23 s to the narrowest distance between the first protrusion 231 -N and the second protrusion 251 -M. The interval has changed.

  The widest gap WC between the first protrusion 231-i and the second discharge electrode 25 s is set narrower than the gap WA between the side electrode 25 c and the groove electrode 23 d shown in FIG. Yes. For example, it is 0.015 mm. Similarly, the widest gap WC between the second protrusion 251-i and the first discharge electrode 23 s is also set narrower than the gap WA between the side electrode 25 c and the groove electrode 23 d. Further, the interval WB between the first connection electrode 23b and the second connection electrode 25b is also narrow, for example, around 0.02 mm. The interval WC is narrower than the interval WB between the first connection electrode 23b and the second connection electrode 25b. That is, the interval between all the first protrusions 231-i and the second discharge electrode 25 s is narrower than the narrower one of the gap WA or the gap WB. Further, the intervals between all the second protrusions 251-i and the first discharge electrode 23 s are narrower than the narrower one of the gap WA or the gap WB.

  For this reason, when the tuning fork type crystal vibrating piece 20 comes into contact with a human body or another device, an electrostatic charge is induced in the first protrusion 231-i and the second protrusion 251-i. The electrostatic charge is concentrated on the first protrusion 231-i and the second protrusion 251-i to form an electric field. In particular, the narrowest interval is concentrated on the narrow protrusion. Since some static charge is accumulated on the first protrusion 231-i and the second protrusion 251-i, the opposite charge of the particles in the air is induced. At this point, an electrostatic discharge reaction occurs between the electrostatic charge of the first protrusion 231-i and the second protrusion 251-i and the induced charge in the air, canceling out the charges carried by both. In other words, the electrostatic charge of the tuning fork type crystal vibrating piece 20 causes an electrostatic discharge reaction with particles in the air through the first protrusion 231-i and the second protrusion 251-i.

  In the electrostatic discharge reaction, the charge of the first protrusion 231-N and the second protrusion 251-M having the smallest interval and the induced charge in the air release electric energy, and an electromigration phenomenon occurs. The discharged electric energy raises the temperature of the first protrusion 231 -N and the second protrusion 251 -M. The total thickness of the lower chromium layer and the upper gold layer is about 250 to 10,000 angstroms. The tips of the first protrusion 231 -N and the second protrusion 251 -M are deformed in a direction in which the distance between the protrusions 231 -N and the second protrusion 251 -M increases due to the high heat generated by the electrostatic discharge reaction. Due to the plurality of times of electromigration, the distance between the first protrusion 231 -N and the second protrusion 251 -M is wider than the distance between the first narrower protrusion 231 -i and the second protrusion 251 -i. However, only the electromigration phenomenon occurs in the next narrow first protrusion 231-i and second protrusion 251-i, and N + M−1 discharge protrusions still exist. For this reason, it can cope with several hundred electrostatic discharge reactions. Further, the distance between all the first protrusions 231-i and the second discharge electrode 25 s is narrower than the narrower one of the gap WA or the gap WB. Further, the intervals between all the second protrusions 251-i and the first discharge electrode 23 s are narrower than the narrower one of the gap WA or the gap WB. Therefore, the original essential electrode does not burn.

  As shown in FIG. 7, there are two surge peaks in the waveform of the discharge current from the human body, the first peak is the discharge from the hands and arms, and the next peak is the discharge from the trunk. Since the interval between the plurality of first protrusions 231-i and the plurality of second protrusions 251-i gradually increases from the narrowest interval, it is an electrostatic discharge having such a plurality of surge peaks. Can also cope.

<< Embodiment 2 >>
FIG. 3A shows a comb-shaped first discharge electrode 23s formed from the first base electrode 23a and a comb-shaped second discharge electrode 25s formed from the second base electrode 25a. Yes. The first discharge electrode 23s forms a plurality of first protrusions 233-i. The second discharge electrode 25s also forms a plurality of second protrusions 253-i. The interval between the first protrusion 233-i and the second protrusion 253-i is formed from a wide interval WC to a narrow interval. The space between the first protrusion 233-N and the second protrusion 253-M is the narrowest distance between the first electrode pattern 23 and the second electrode pattern 25, and is set to 0.008 mm, for example.

  The widest distance WC between the first protrusion 233-i and the second protrusion 253-i is set narrower than the gap WA between the side electrode 25c and the groove electrode 23d shown in FIG. Yes. The interval WC is narrower than the interval WB between the first connection electrode 23b and the second connection electrode 25b, and is, for example, around 0.02 mm. For this reason, when the tuning fork type crystal vibrating piece 20 comes into contact with a human body or another device, an electrostatic charge is induced in the first protrusion 233-i and the second protrusion 253-i.

  In the electrostatic discharge reaction, the charges of the first protrusions 233-i and the second protrusions 253-i and the induced charges in the air release electric energy and reach a more stable state. The first protrusion 233-i and the second protrusion 253-i are burned by the high heat generated by the electrostatic discharge reaction generated by the first protrusion 233-i and the second protrusion 253-i. However, since only one discharge protrusion is burned and N + M−1 discharge protrusions still exist, it is possible to cope with several tens of electrostatic discharge reactions. Further, since the interval between all the first protrusions 233-i and the second protrusions 253-i is narrower than the narrower one of the gap WA or the gap WB, the original essential electrode pattern is not burnt.

<< Embodiment 3 >>
The base 29 shown in FIG. 3B includes a comb-shaped first discharge electrode 23s and a second base electrode 25a formed from the first base electrode 23a. The first discharge electrode 23s forms a plurality of first protrusions 233-i, but the second base electrode 25a is not formed with discharge protrusions as discharge electrodes. The interval between the first protrusion 233-i and the second base electrode 25a is formed from a wide interval WC to a narrow interval. The space between the first protrusion 233-N and the second base electrode 25a is the narrowest distance between the first electrode pattern 23 and the second electrode pattern 25, and is set to 0.008 mm, for example.

  The widest gap WC between the first protrusion 233-i and the second base electrode 25a is set to be narrower than the gap WA between the side electrode 25c and the groove electrode 23d shown in FIG. . The interval WC is narrower than the interval WB between the first connection electrode 23b and the second connection electrode 25b, and is, for example, around 0.02 mm. For this reason, when the tuning fork type crystal vibrating piece 20 comes into contact with a human body or another device, an electrostatic charge is induced in the first protrusion 233-i.

  In the electrostatic discharge reaction, the charge of the first protrusion 233-i and the induced charge in the air release electric energy and reach a more stable state. The first protrusion 233-i and the second protrusion 253-i are burned by the high heat generated by the electrostatic discharge reaction generated at the first protrusion 233-i. However, since only one discharge protrusion is burned and N-1 discharge protrusions still exist, it is possible to cope with several tens of electrostatic discharge reactions. Further, since the interval between all the first protrusions 233-i and the second protrusions 253-i is narrower than the narrower one of the gap WA or the gap WB, the original essential electrode pattern is not burnt.

<< Embodiment 4 >>
The base 29 shown in FIG. 4 (a) has a comb-like first discharge electrode 23s formed from the first base electrode 23a and a comb-like second discharge electrode formed from the second base electrode 25a. 25 s. In the second embodiment, the discharge protrusion is in the Y direction, but in the fourth embodiment, the discharge protrusion is in the X direction. The interval between the first protrusion 235-i and the second protrusion 255-i is formed from a wide interval WC to a narrow interval. The space between the first protrusion 235-N and the second protrusion 255-M is the narrowest distance between the first electrode pattern 23 and the second electrode pattern 25, and is set to 0.008 mm, for example.

  Although not shown in FIGS. 3 and 4, the discharge protrusion may be inclined by 45 degrees from the Y direction. Thus, even in the small tuning-fork type crystal vibrating piece 20, the base 29 has a larger space than the other parts, and therefore, the comb-shaped first protrusion 235 -N and second protrusion 255 -M Can be formed in any direction.

<< Embodiment 5 >>
The base 29 shown in FIG. 4B includes a comb-shaped first discharge electrode 23s and a second base electrode 25a formed from the first base electrode 23a. The first discharge electrode 23s forms a plurality of first protrusions 237-i, and the second discharge electrode 25s also forms a plurality of first protrusions 237-i. The first protrusion 237-i faces the second base electrode 25a, and the distance between the first protrusion 237-i and the second base electrode 25a is formed from a wide distance WC to a narrow distance. Similarly, the second protrusion 257-i faces the first base electrode 23a, and the distance between the second protrusion 257-i and the first base electrode 23a is formed from a wide space WC to a narrow space. The space between the first protrusion 237-N and the second base electrode 25a is the narrowest distance between the first electrode pattern 23 and the second electrode pattern 25, and is set to 0.008 mm, for example.

  In FIG. 4B, a plurality of first protrusions 237-i and a plurality of second protrusions 257-i are provided in a two-stage arrangement. The discharge protrusions as shown in FIG. 4A may be opposed to each other and arranged in a two-stage arrangement.

  In the present invention, the electrostatic charge in the tuning-fork type crystal vibrating piece 20 is concentrated on the discharge protrusion and the like, thereby preventing the electrode pattern region from being electrically disturbed. Furthermore, the electric charge in the air is attracted to the electric field of the discharge protrusion. When a certain amount of electrostatic charge builds up an electric field with a certain intensity of the discharge protrusion, they undergo an electrostatic discharge reaction with particles in the air. The ESD breakdown voltage is substantially improved without damaging the electrode pattern region.

<Configuration of surface mount (SMD) type tuning fork type vibrator>
FIG. 5A is a schematic cross-sectional view showing an SMD type tuning fork type crystal resonator 50 according to the present embodiment.
The SMD type tuning fork type crystal resonator 50 uses the tuning fork type crystal vibrating piece 20 described above. The SMD type tuning fork vibrator 50 has a box-shaped package 52 having a space inside. The package 52 has a base portion 54 at the bottom thereof. The base portion 54 is formed by laminating and sintering a plurality of substrates formed by molding ceramic green sheets made of an aluminum oxide-based kneaded material.

  A sealing material 58 plated with gold on nickel is provided on the ceramic base portion 54, and the sealing material 58 is formed of the same material as the cover 56 made of Kovar or the like. . A lid 56 is placed on the sealing material 58, and the lid 56 is fixed by the sealing material 58 by a technique such as seam welding. These base portion 54, sealing material 58 and lid 56 form a hollow box.

  A package-side electrode 59 is provided on the base portion 54 of the package 52 thus formed. On the package side electrode 59, base electrodes 23a and 25a of the tuning-fork type crystal vibrating piece 20 are fixed via a conductive adhesive or the like. The package side electrode 59 is connected to an electrode part in which nickel plating and gold plating are performed on a tungsten metallization formed outside the package.

  The tuning fork type crystal vibrating piece 20 vibrates when a constant current is applied from the electrode portion. At this time, even if a human body charged with static electricity touches the SMD type tuning fork vibrator 50 or a device charged with static electricity touches the SMD type tuning fork vibrator 50, Since the electrostatic discharge discharge protrusions described with reference to FIGS. 2 to 4 are formed, no short circuit or the like occurs between the electrode patterns with the narrowest spacing. Therefore, the SMD type tuning fork vibrator 50 that can sufficiently exhibit the performance of the H type tuning fork type crystal vibrating piece 20 is obtained. Further, the SMD type tuning fork vibrator 50 can be manufactured without increasing the manufacturing cost.

<Configuration of tuning fork crystal oscillator>
FIG. 5B shows a tuning fork crystal oscillator 60. The digital tuning fork crystal oscillator 60 has the same configuration in many parts as the SMD type tuning fork resonator 50 described above. Therefore, the configurations, operations, and the like of the SMD type tuning fork vibrator 50 and the tuning fork type crystal vibrating piece 20 are denoted by the same reference numerals and the description thereof is omitted.

  In the tuning fork type crystal oscillator 60 shown in FIG. 5B, an integrated circuit 61 is disposed on the base portion 54 below the tuning fork type crystal vibrating piece 20 of the SMD type tuning fork vibrator 50 shown in FIG. It is what. That is, in the tuning fork crystal oscillator 60, when the tuning fork type crystal vibrating piece 20 disposed therein vibrates, the vibration is input to the integrated circuit 61, and then functions as an oscillator by extracting a predetermined frequency signal. Will do.

  The tuning fork type crystal vibrating piece 20 vibrates when a constant current is applied from the electrode portion. At this time, even if a human body charged with static electricity touches the tuning fork type crystal oscillator 60 or a device charged with static electricity touches the tuning fork type crystal oscillator 60, the tuning fork type quartz crystal vibrating piece 20 has the following FIGS. Since the discharge protrusions for electrostatic discharge described in (1) are formed, no short circuit or the like occurs between the electrode patterns having the narrowest intervals. Therefore, the tuning-fork type crystal oscillator 60 that can sufficiently exhibit the performance of the H-type tuning-fork type crystal vibrating piece 20 is obtained. Further, the tuning fork type crystal oscillator 60 can be manufactured without increasing the manufacturing cost.

<Configuration of cylinder type tuning fork crystal oscillator>
FIG. 5C is a schematic diagram showing a cylinder type tuning fork vibrator 70. The cylinder type tuning fork vibrator 70 uses the tuning fork type crystal vibrating piece 20 described above.
As shown in FIG. 5C, the cylinder type tuning fork vibrator 70 has a metal cap 75 for accommodating the tuning fork type crystal vibrating piece 20 therein. The cap 75 is press-fitted into the stem 73 so that the inside thereof is maintained in a vacuum state.

Two leads 71 for holding the tuning fork type crystal vibrating piece 20 accommodated in the cap 75 are arranged.
The tuning fork type crystal vibrating piece 20 vibrates when a constant current is applied from the electrode portion. At this time, even if a human body charged with static electricity touches the cylinder-type tuning fork vibrator 70 or a device charged with static electricity touches the cylinder-type tuning fork vibrator 70, the tuning-fork type crystal vibrating piece 20 has the structure shown in FIG. Since the discharge protrusion for electrostatic discharge described with reference to FIG. 4 is formed, a short circuit or the like does not occur between the electrode patterns with the narrowest spacing. Therefore, the cylinder-type tuning fork vibrator 70 can sufficiently exhibit the performance of the H-type tuning fork type crystal vibrating piece 20. Further, the cylinder type tuning fork vibrator 70 can be manufactured without increasing the manufacturing cost.

<Manufacturing process of SMD type tuning fork vibrator 50>
FIG. 6 is a flowchart showing all steps of manufacturing the SMD type tuning fork vibrator 50 described with reference to FIG. The manufacturing process of the tuning fork crystal oscillator 60 or the cylinder type tuning fork vibrator 70 is slightly different, but the outline is the same.
<< Process for Forming External Shape of Quartz Vibrating Piece >>
In step S112, a corrosion resistant film is formed on the entire surface of the quartz single crystal wafer 10 by a technique such as sputtering or vapor deposition. That is, when using the crystal single crystal wafer 10 as a piezoelectric material, it is difficult to directly form a film of gold (Au), silver (Ag), or the like, so that chromium (Cr), titanium (Ti), etc. Is used. That is, in this embodiment, a metal film in which a gold layer is stacked on a chromium layer is used as the corrosion resistant film.

  In step S114, a photoresist layer is uniformly applied to the entire surface of the quartz single crystal wafer 10 on which the chromium layer and the gold layer are formed by a technique such as spin coating. As the photoresist layer, for example, a positive photoresist made of novolak resin can be used.

  Next, in step S116, the quartz single crystal wafer 10 on which the photoresist layer is applied to the pattern of the H-type tuning fork type quartz vibrating piece 20 drawn on the first photomask is exposed using an exposure apparatus. In step S116, both sides are exposed using i-line exposure light of 365 nm using a double-side exposure apparatus.

  In step S118, the photoresist layer of the crystal single crystal wafer 10 is developed, and the exposed photoresist layer is removed. Furthermore, the gold layer exposed from the photoresist layer is etched using, for example, an aqueous solution of iodine and potassium iodide. Next, the chromium layer exposed by removing the gold layer is etched with, for example, an aqueous solution of ceric ammonium nitrate and acetic acid. The concentration of the aqueous solution, the temperature, and the time of immersion in the aqueous solution are adjusted so that excess portions are not eroded. Thus, the corrosion resistant film can be removed. Next, using a hydrofluoric acid solution as an etchant, the quartz material exposed from the photoresist layer and the corrosion-resistant film is wet-etched so that the outer shape of the tuning-fork type quartz vibrating piece 20 is obtained. This wet etching takes about 6 hours to about 15 hours, although the time varies depending on the concentration, type and temperature of the hydrofluoric acid solution.

In Step S120, the tuning-fork type crystal vibrating piece 20 shown in FIG. 2 or 4 is formed by removing the photoresist layer and the corrosion-resistant film that are no longer needed.
<< Electrode Formation Process >>
In step S122, the tuning fork type crystal vibrating piece 20 is washed with pure water, and a metal film for forming an excitation electrode or the like as a drive electrode is formed on the entire surface of the tuning fork type crystal vibrating piece 20 by a technique such as vapor deposition or sputtering. . This metal film is composed of a chromium layer as a base and a gold layer. For example, the chromium layer has a thickness of 150 to 5000 angstroms and the gold layer has a thickness of 100 to 5000 angstroms.

In step S124, a photoresist is applied to the entire surface by spraying.
In step S126, a second photomask corresponding to the electrode pattern is prepared, and the quartz single crystal wafer 10 on which the electrode layer is coated with the photoresist layer is exposed. The electrode pattern for electrostatic discharge described in FIGS. 2 to 4 is drawn on the second photomask. Since this electrode pattern needs to be formed on both surfaces of the tuning fork type crystal vibrating piece 20, in step S126, both surfaces of the tuning fork type crystal vibrating piece 20 are exposed using i-line exposure light of 365 nm. The double-sided exposure device can be used to expose both sides of the quartz crystal vibrating piece 20 at one time. Alternatively, the single-sided exposure device can be used to expose one side of the quartz crystal vibrating piece 20 and turn the quartz crystal vibrating piece 20 over to expose the other side. It can also be exposed.

In step S128, after the photoresist layer is developed, the exposed photoresist is removed. The remaining photoresist becomes a photoresist corresponding to the electrode pattern.
Next, in step S128, the metal film to be an electrode is etched. That is, the gold layer exposed from the photoresist layer corresponding to the electrode pattern is etched with, for example, an aqueous solution of iodine and potassium iodide, and then the chromium layer is etched with, for example, an aqueous solution of ceric ammonium nitrate and acetic acid. Subsequently, the photoresist is removed in step S130. Through these steps, an excitation electrode or the like is formed on the tuning fork type crystal vibrating piece 20 with an accurate position and electrode width.

In step S <b> 132, the tuning fork type crystal vibrating piece 20 is cut from the crystal single crystal wafer 10. If necessary, it is checked whether or not the connecting portion 28 is cut off outside the end portion of the base portion 29.
<< Frequency adjustment and packaging process >>
Since the tuning fork type crystal vibrating piece 20 having the electrode formed thereon is obtained through the above steps, in step S134, the tuning fork type crystal vibrating piece 20 is bonded to the ceramic package 52 shown in FIG. Specifically, the conductive adhesive is temporarily cured by placing it on the conductive adhesive coated with the electrode portions 23a and 25a of the base 29 of the tuning-fork type crystal vibrating piece 20. Next, the conductive adhesive is fully cured in a curing furnace.

  In step S136, the vibrating arm 21 of the tuning-fork type quartz vibrating piece 20 is further irradiated with laser light to evaporate and sublimate part of the quartz single crystal wafer 10 or the weight metal of the vibrating arm 21, and the frequency by the mass reduction method. Make adjustments.

  Next, in step S 138, the package 51 containing the crystal vibrating piece 20 is moved into a vacuum chamber or the like, and the lid body 59 is sealed with the sealing material 58. Subsequently, in step S138, the SMD type tuning fork vibrator 50 is finally inspected for driving characteristics and the like, and the SMD type tuning fork vibrator 50 is completed.

  In the above embodiment, the tuning fork type crystal resonator has been described. However, the present invention is not limited to this, and a crystal resonator having another shape may be used.

(A) is a diagram showing the overall configuration of the tuning-fork type crystal vibrating piece 20, and (b) is a BB cross-sectional view of one vibrating arm 21 of the tuning-fork type crystal vibrating piece 20. FIG. 3 is an enlarged view of an electrostatic discharge electrode pattern according to the first embodiment, in which a base 29 of the tuning-fork type crystal vibrating piece 20 is enlarged. It is a figure of the electrode pattern of electrostatic discharge of Embodiment 2 and Embodiment 3. It is a figure of the electrode pattern of electrostatic discharge of Embodiment 4 and Embodiment 5. 3 is a diagram showing a ceramic package tuning fork resonator 50, a tuning fork crystal oscillator 60, and a cylinder type tuning fork resonator 70 using the tuning fork crystal resonator element 20. FIG. 5 is a flowchart showing all steps of manufacturing a ceramic package tuning fork resonator 50; It is the figure which showed an example of the discharge current waveform of the static electricity from a human body.

Explanation of symbols

10: Crystal single crystal wafer 20: Tuning fork type crystal vibrating piece,
23 ... 1st electrode (pattern)
25 ... Second electrode (pattern)
231, 233, 235... First electrode discharge protrusion 251, 253, 255... Second electrode discharge protrusion 50... Ceramic package tuning fork vibrator 60. Tuning fork crystal oscillator 70. The narrowest gap WB between the electrode 25c and the groove electrode 23d ... The narrowest gap WC between the first connection electrode 23b and the second connection electrode 25b ... The widest gap in the discharge protrusion

Claims (7)

A tuning-fork type quartz substrate having a plate-like base portion having front and back surfaces and a pair of vibrating arms extending from the base portion;
A first excitation electrode and a second excitation electrode respectively formed on the pair of vibrating arms;
A first base electrode connected to the first excitation electrode and a second base electrode connected to the second excitation electrode, arranged on the front and back surfaces of the base;
A plurality of discharge protrusions formed on the first base electrode and extending from the first base electrode to the second base electrode ;
A tuning fork type characterized in that the widest gap between the plurality of discharge protrusions of the first base electrode and the second base electrode is narrower than the narrowest gap between the first excitation electrode and the second excitation electrode . Crystal vibrating piece. The pair of vibrating arms has a groove,
The first excitation electrode includes a first groove electrode formed in a groove portion of one of the vibrating arms and a first side electrode formed on a side surface of the other vibrating arm,
2. The second excitation electrode includes a second groove electrode formed in a groove portion of the other vibrating arm and a second side electrode formed on a side surface of the one vibrating arm. Crystal resonator element according to claim 1.   The plurality of discharge protrusions formed on the first base electrode are formed in a sawtooth shape, and the second base electrode opposed to the plurality of discharge protrusions is linear without the discharge protrusion. Item 4. The quartz crystal resonator element according to Item 1.   2. The quartz crystal vibrating piece according to claim 1, wherein the first base electrode and the second base electrode are formed in a spiral shape that moves away from the center as they turn relative to each other.   5. The quartz crystal resonator element according to claim 1, wherein intervals between the plurality of discharge protrusions of the first base electrode and the second base electrode are different from each other. 6. 6. The quartz crystal resonator element according to claim 1, wherein the first base electrode and the second base electrode have a thickness of 250 Å to 10000 Å. The tuning-fork type crystal vibrating piece according to any one of claims 1 to 6 ,
A package for vacuum-sealing the tuning-fork type crystal vibrating piece;
A vibrating device having.