WO1995011548A1

WO1995011548A1 - Rectangular at-cut quartz crystal plate, quartz crystal unit, and quartz oscillator and manufacture of quartz crystal plate

Info

Publication number: WO1995011548A1
Application number: PCT/JP1994/001721
Authority: WO
Inventors: Itaru Nagai
Original assignee: Seiko Epson Corporation
Priority date: 1993-10-18
Filing date: 1994-10-13
Publication date: 1995-04-27
Also published as: JP3456213B2; DE4497992C2; DE4497992T1

Abstract

A quartz crystal unit which has a small size and light weight and can oscillate at overtone frequencies. The aspect ratio (w/t) of the quartz plate at which no coupling with spurious vibrations occurs within the operating temperature range even when the width and length of the quartz plate are below 1.5 mm and below 4.7 mm, respectively, is specified. It has been experimentally confirmed that an AT-cut rectangular quartz plate having an aspect ratio of 8.48 ± 0.05, 12.18 ± 0.05, 13.22 ± 0.07, 14.78 ± 0.07, or 15.57 ± 0.07 has excellent temperature characteristics. In addition, several factors which are essential to providing a quartz plate having a low equivalent series resistance have been found.

Description

Description Rectangular AT-cut crystal blank, crystal resonator, crystal resonator and crystal oscillator, and method for manufacturing crystal blank Technical field '' The present invention relates to a crystal blank, a crystal resonator, a crystal resonator, and a crystal resonator. The present invention relates to an oscillator used, and particularly to an AT-cut rectangular water crystal piece that performs overtone oscillation. Further, the present invention relates to a manufacturing method suitable for forming these quartz pieces, quartz vibrators, and quartz vibrators. BACKGROUND ART Quartz resonators are resonators that utilize the piezoelectric phenomenon of a single crystal of a crystal, and are currently used in many fields because they provide an oscillation source with a very stable frequency. In particular, crystal oscillators and oscillators are used as reference clock sources in various electronic equipment fields such as communication equipment and information processing equipment. In recent years, in the field of such electronic devices, miniaturization, weight reduction, and further increase in operating speed due to higher frequency have been progressing. There is an urgent need to realize a crystal oscillator that can oscillate.

The AT-cut crystal blank cut out of a single crystal of quartz has good frequency-temperature characteristics with respect to temperature change, and has little change over time in frequency. This AT-cut crystal blank is processed into a long rectangular shape in the X-axis direction with a length in the X-axis direction, a thickness t in the Y'-axis direction, and a width w in the Ζ'-axis direction. Since it can be sealed in a miniaturized crystal holder such as the one described above, it is a suitable crystal piece that constitutes a small and high-performance crystal resonator in combination with the above-mentioned good characteristics. Note that X 轴, Y axis, and Z 電気 are the electric, mechanical, and optical axes of the single crystal, respectively, and the Y 'axis and Z' axis are the Y axis and the Z axis when rotated about 35 ° around the X axis. The Z axis.

In order to provide an oscillator using a crystal oscillator as a surface mount device (SMD) that can be mounted on the surface of a circuit board in the same mounting method as an IC, etc. It is necessary to store the crystal unit in a cage with a diameter of about 2 mm or less and a length of about 6 mm. In order to construct such a crystal unit, a crystal element that can be stored in a cylinder-shaped crystal holder and oscillates at the fundamental frequency is described in the 21st EM Symposium (The Institute of Electrical Engineers of Japan, The meeting was held on May 22, 1992 by the organizer. See Proceedings P37-42). However, the frequency band that can be covered by a crystal oscillator that oscillates at the fundamental frequency is only a low and limited frequency band of approximately 17 MHz to 40 MHz, which is high in the fields of the above-mentioned electronic devices. It cannot cover the high frequency band exceeding 40 MHz required for speeding up.

Since the thickness t of the AT-cut crystal blank is inversely proportional to the frequency, when the fundamental frequency exceeds 40 MHz, the thickness of the crystal blank becomes 42 m or less, making processing difficult. Therefore, in order to realize a crystal resonator that oscillates at a high frequency, it is necessary to realize a crystal chip for overtone oscillation and a crystal resonator using the same. In order to be able to store a crystal piece in a small crystal holder as described above, its length i must be about 5 mm or less and its width w must be about 1.5 mm or less. However, when such a small AT-cut crystal blank is caused to overtone oscillate, the main vibration, the thickness reduction, In addition to vibration, spurious vibration is likely to be excited near the main vibration. Then, the spurious vibration and the main vibration are coupled to generate a frequency jump even with a small temperature change of 5 to 10 ° C. For this reason, even with the small crystal piece described above, the frequency temperature characteristics of the cubic curve, which is a characteristic of the AT-cut crystal resonator, can be controlled within the specified temperature range (about 120 to 180 ° C). The shape of the resulting crystal blank, especially the side ratio (width w / thickness t), has not been found.

Furthermore, in the case of a quartz vibrator using a small quartz piece, the energy confinement of the main vibration, that is, the thickness-shear vibration, tends to be insufficient, so that there is a problem that the equivalent series resistance Rr deteriorates. In the case of the above-mentioned small quartz pieces and quartz vibrators, especially those that generate overtone oscillation, the equivalent series resistance R r depends on the dimensions, surface roughness of the surface processing, electrode width, and electrode weight. No effect has been identified.

Regarding the surface processing state, it is known that increasing the surface roughness can reduce the equivalent series resistance R r, but on the other hand, there is a phenomenon in which the value of the equivalent series resistance R r varies. For this reason, in the case of using a small crystal piece as described above, simply improving the surface roughness of the surface lowers the yield and cannot provide a high-performance crystal piece at low cost.

Therefore, in the present invention, a crystal blank, a crystal vibrator, a crystal vibrator, a crystal vibrator, and a crystal vibrator that are small and light enough to be adopted as an SMD like an IC or the like, and are capable of oscillating high frequency. The purpose is to provide an oscillator. For this reason, even if the length ^ is about 5 mm or less and the width w is about 1.5 mm or less, we found a shape of a crystal piece that oscillates overtones with good temperature characteristics. It is intended to provide In addition, even a crystal resonator using such a small crystal blank has a low equivalent series resistance Rr, and can be used for practical crystal blanks and water. It is also an object to provide a crystal oscillator and a crystal oscillator. It is still another object of the present invention to provide a manufacturing method capable of providing a crystal blank, a crystal resonator, and a crystal resonator having good temperature characteristics and an equivalent series resistance Rr with high yield. DISCLOSURE OF THE INVENTION In order to realize a small-sized and high-frequency crystal resonator as described above, the present applicant has repeated several experiments and measurements to obtain a small crystal piece for overtone oscillation. It was possible to find a vibrator having no coupling with spurious vibrations within a predetermined temperature range required for the vibrator. It is a rectangular AT-cut crystal piece for a third-order overtone crystal unit, having a length in the X-axis direction, a thickness t in the Y'-axis direction, and a width w in the Z'-axis direction. The range of the side ratio t defined by the width w and the thickness t is 8.48 ± 0.05, 12.18 ± 0.05, 13.22 ± 0.07 , 14.78 ± 0.07, and 15.5.7 ± 0.07. A rectangular AT crystal blank.

By repeating experiments and measurements, the applicant of the present application has determined that such a crystal piece has a length in the X-axis direction, and the range of this length is 400 to 470,000. m, and if the width w is in the range of 800 to 150 m, a crystal resonator having good equivalent series resistance is used. Found that it can be formed.

Furthermore, having a surface crystal piece is etched, the surface maximum height of roughness R _m range ,, is 0. 2 to 0. 7 m, preferably 0.1 3 It was also found that a good equivalent series resistance can be obtained at 0.6 m. In the conventional crystal blank, the equivalent series resistance was reduced by making the surface as smooth as possible, but the applicant of the present application has found that a good equivalent series resistance can be obtained within the above range of surface roughness. At the same time, we found that we could obtain extremely high yield crystal blanks.

Such a crystal piece can be manufactured by lapping the surface of a quartz crystal AT-cut wafer and then etching it. At this time, it is desirable that the thickness of one side reduced by the etching process, that is, half of the thickness reduction (hereinafter referred to as the “etching amount”) is set to 0.5 to 2.5 m. desired to the range of the maximum height R _m of the surface roughness of the surface of "the 0. 3 ~ 0. 7 m arbitrariness. in lapping performing finishing etching the immediately preceding surface, abrasive grains having an average grain It is effective to use an alumina-based abrasive having a diameter of 2.5 to 3 m, and in the etching process, a hydrofluoric acid of 10 to 33% by weight can be used as an etching solution.

In addition, in relation to the electrodes formed on the surfaces facing each other across the thickness t of the crystal piece, the width W of the electrode along the Z 'axis is smaller than the width w of the rectangular AT-cut-. The distance between the end in the width W direction and the end in the width w direction of the rectangular AT-cut crystal piece is 75 to 230 for a crystal piece with a side ratio t in the range of 8.48 ± 0.05. It has been found that good equivalent series resistance and temperature characteristics can be obtained when the distance is zm, preferably 75 to 200 m. Also, the range of the side ratio w / t is 12.18 ± 0.05, 13.22 ± 0.07, 14.78 ± 0.07, and 15.57+ For any of the rectangular AT-cut quartz pieces of 0.07, Ί5 to 340 m is preferable, and 750 to 200 m is more preferable. Furthermore, regarding the relationship with the film formation amount such as electrode deposition, the rectangular AT force depends on the presence or absence of the electrode. It has been found that a good equivalent series resistance can be obtained when the value is 700,000 to 300,000 ppm in terms of the change in the frequency of the crystal blank.

If a crystal resonator is formed using such a rectangular AT-cut crystal piece, it is possible to provide a crystal resonator that is small, light, and capable of oscillating high frequencies. As a support mechanism for the crystal blank, a support mechanism in which the electrodes are joined to the lead with solder or a conductive adhesive to support one end in the X-axis direction of the crystal blank can be adopted. In addition, since the crystal piece in the above range is small and can oscillate at a stable high frequency, the diameter range is 2.0 ± 0.2 mm and the length range is 6.0 ± 0.5 mm. Can be stored in the cage. The crystal holder may be molded by a molding member, and by molding together with an integrated circuit device having an oscillation circuit, a crystal oscillator suitable for mounting on the surface of a substrate can be realized.

The configuration and the range of each element as described above are disclosed in detail in the best mode for carrying out the invention described below. However, the invention of the present application is as described in the claims, and is applied to a crystal blank, a crystal resonator, a crystal resonator, etc. of the following experimental examples described in the best mode for carrying out the invention. It is not limited. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing an outline of a crystal blank manufactured in an embodiment of the present invention.

FIG. 2 is a flowchart showing steps of manufacturing a crystal blank, a crystal resonator, and a crystal resonator according to an embodiment of the present invention.

FIG. 3 is a plan view showing the configuration of the crystal resonator according to the embodiment of the present invention. FIG. 4 is a perspective view showing an outline of the crystal resonator according to the embodiment of the present invention.

FIG. 5 is a structural view of the inside of the crystal unit shown in FIG. 4 as viewed from the Y′-axis direction.

FIG. 6 is a structural view of the inside of the crystal unit shown in FIG. 4 as viewed from the Z′-axis direction.

FIG. 7 is a graph showing temperature characteristics of a crystal resonator using a crystal piece having a side ratio E of about 12.18, respectively.

FIG. 8 is a diagram summarizing the coupling state of a crystal resonator using a crystal piece having a side ratio E of about 12.18 with spurious vibration.

FIG. 9 is a graph showing a temperature characteristic of a crystal unit using a crystal piece having a side ratio E of about 8.48.

FIG. 10 is a diagram summarizing the coupling state of a crystal resonator using a crystal piece having a side ratio E of about 8.48 with spurious vibration.

FIG. 11 is a graph showing a temperature characteristic of a crystal unit using a crystal piece having a side ratio E of about 15.5.7, respectively.

FIG. 12 is a diagram summarizing the coupling state of a crystal resonator using a crystal piece having a side ratio E of around 15.5.77 with spurious vibration.

FIG. 13 is a diagram summarizing the coupling state of a crystal resonator using a crystal piece having a side ratio E of about 13.3.22 with spurious vibration.

FIG. 14 is a diagram summarizing a coupling state of a crystal resonator using a crystal piece having a side ratio E of about 14.7.88 with spurious vibration.

FIG. 15 is a diagram showing a frequency range that can be covered by the crystal unit using the crystal piece having the above-described side ratio.

Fig. 16 is a graph showing the relationship between the length ^ of the crystal piece and the equivalent series resistance Rr. Figure 17 is a graph showing the relationship between the width w of the crystal blank and the equivalent series resistance Rr.

FIG. 18 is a graph showing the relationship between the surface roughness of the etched surface of a quartz piece having a side ratio E of 12.18 and the equivalent series resistance Rr.

FIG. 19 is a graph showing the relationship between the surface roughness of the surface of a crystal piece having a side ratio E of 8.48 after etching and the equivalent series resistance Rr.

FIG. 20 is a graph showing the relationship between the surface roughness of the surface of a quartz piece having a side ratio E of 15.5.77 after etching and the equivalent series resistance Rr.

Figure 21 shows a comparison between the variation in the value of the equivalent series resistance Rr of the crystal blank etched after polishing and the variation in the value of the equivalent series resistance Rr of the crystal blank etched after wrapping. is there.

FIG. 22 is a graph showing the relationship between the amount of etching and the surface roughness of the surface of the crystal blank.

FIG. 23 is a graph showing the relationship between the amount of etching and the equivalent series resistance Rr.

FIG. 24 is a graph showing a temperature characteristic of a crystal unit having a side ratio E of 12.18 and a crystal resonator when the interval D is changed.

FIG. 25 is a graph showing the temperature characteristics of a quartz crystal having a side ratio E of 8.48 and a quartz resonator when the interval D is changed.

FIG. 26 is a graph showing the temperature characteristics of a quartz crystal element having a side ratio E of 15.5.57 and varying the interval D, respectively.

FIG. 27 is a graph showing the relationship between the distance D between the electrode and the end of the crystal piece and the equivalent series resistance Rr.

FIG. 28 is a graph showing the relationship between the amount of change in frequency during electrode deposition and the equivalent series resistance Rr.

Figure 29 shows an outline of a crystal unit in which the crystal unit is molded with resin. FIG.

FIG. 30 is a cross-sectional view of a crystal oscillator in which a crystal unit and an IC having an oscillation circuit are molded with resin. BEST MODE FOR CARRYING OUT THE INVENTION Quartz Crystal Resonator Manufacturing Process FIG. 1 shows an outline of a crystal blank 1 according to the present invention. The crystal blank 1 of this example is a rectangular AT cut crystal blank cut out of a single crystal of crystal and processed into a rectangular shape, has the illustrated coordinate system XY 'Z' axis, and has the X-axis. It has a length ^, a thickness t along the Y 'axis, and a width w along the Z' axis.

FIG. 2 shows the steps of manufacturing the crystal blank, the crystal resonator, and the crystal resonator according to the present invention. First, in step 11, a single crystal of quartz is cut into a wafer at a predetermined angle (AT cut). Next, in step 12, the surface of the wafer is roughly lapped by using a silicon carbide abrasive having a grain size of about # 150. Further, in step 13, a final lapping process is performed using an alumina-based abrasive having an average grain size of 2.5 to 3 m. Maximum surface of wafer surface roughness by the lapping processing height R _m. X is made to be 0. 7 m or less. Maximum height of surface roughness in this specification

Is a value measured using a surface roughness measuring instrument “Tarisurf 6” manufactured by Rankera-Hobson.

In finishing the surface of the crystal blank 1 of the present example, polishing using a polishing agent as in the past was not performed. Also, if necessary, a silicon carbide material having a particle size of about # 300 between steps 12 and 13 can be used. Intermediate lap processing using an abrasive may be performed.

Next, a plurality of wafers wrapped in step 14 are attached to each other, and these wafers are cut so as to have a predetermined side ratio or a predetermined length to produce a crystal piece having a predetermined size. First, in step 15, X-cutting is performed by cutting the wafer at a plane perpendicular to the X-axis. Then, in steps 16 and 17, lapping of the cut surface is performed under the same conditions as in steps 12 and 13 described above. When the lapping process on the plane perpendicular to the X axis is completed, in step 18, the wafer is cut along a plane perpendicular to the Z axis. Further, lapping of the cut surface in steps 19 and 20 is performed in the same manner as in the above-described step. While the edge of the wafer cut from the single crystal is about several tens of millimeters on a side, the edge of the wafer cut into a crystal piece of a predetermined size is very small. For this reason, a predetermined surface roughness can be obtained even for the cut surface of a small crystal piece by bonding the cut wafers with a honey and cutting them and then lapping the end surfaces. I am trying to be.

When the lapping of the end face is completed, each crystal piece is separated in step 21 and washed in step 22. The length and width w of the crystal piece are measured using a dial gauge with a measurement accuracy range of 1 m, and the dial gauge used for this measurement is used after calibrating the scale using a standard block each time. Is done. The thickness t is measured by oscillating a crystal blank using a plate oscillator without attaching electrodes, and measuring the frequency. That is, the thickness t is obtained from the frequency measured by the following equation.

t = 3 X C / f (1)

Here, C is a frequency constant of the fundamental wave, which is 1670 × m · MHz. F is the oscillation frequency (MHz) of the third overtone of the crystal blank. The oscillation frequency was measured to the order of 1 kHz, and the thickness t (τη) Seeking.

In this example, a crystal piece that can be stored in a cylinder-shaped holder having a diameter of about 2 mm and a length of about 6 mm is formed by the above-described process. For this reason, taking the dimensions of the base supporting the crystal blank into account, the upper limit of the length 水晶 of the crystal blank is set to 470 m, and the upper limit of the width w is taken to be 150 / m in consideration of the inner diameter of the cage. I have.

Next, in step 23, each crystal piece is etched. At this time, in this example, 10 to 30% by weight of hydrofluoric acid is used as the etching solution. By performing the etching, the distortion due to the lapping process and the affected layer can be removed.

Further, in step 24, an electrode material is formed on both surfaces sandwiching the thickness t, that is, on the XZ ′ surface by vapor deposition or sputtering. In this example, the electrode is formed by chromium, nickel, silver, gold, or a laminate of these. FIG. 3 shows an outline of a crystal resonator 5 in which electrodes are deposited on a crystal blank 1. In the quartz vibrator of this example, a substantially rectangular excitation electrode 2 having a width W is formed substantially in the center of the surface of the quartz piece 1 and extends along the longitudinal direction of the quartz piece. Further, the connection electrode 3 is formed from the excitation electrode 2 toward one corner 1 a in the longitudinal direction of the crystal blank 1, and an adjacent corner 1 b is formed on the surface opposite to the crystal blank 1. The connection electrode 3 is formed so as to correspond to the formed excitation electrode.

The electrode is formed so that the distance D between the longitudinal end 2a of the electrode formed on the surface of the crystal blank 1 and the longitudinal end 1c of the crystal blank 1 becomes a predetermined value. At the same time, and the amount of film formation of the electrode is also controlled by monitoring the oscillation frequency of the crystal blank 1. This is also described in more detail below.

Next, in step 25, a mechanism to support the quartz vibrator and supply current to the electrodes Attach a lead that also has the function of The lead may be connected to the electrode by soldering, or may be connected using a conductive adhesive such as epoxy or polyimide containing silver filler.

In step 26, deposit a small amount of silver on the electrode or

The final adjustment of the oscillation frequency of the crystal resonator is made by removing step 5. Next, in step 27, the quartz oscillator is inserted into a cylindrical holder while heating the quartz oscillator so that the adsorbed gas is released in a vacuum chamber, and sealed by vacuum to create a quartz oscillator. Instead of vacuum sealing, an inert gas may of course be sealed in the holder.

10 Figure 4 shows the outline of the crystal unit, and Figures 5 and 6 show the cross sections of the crystal unit. The crystal unit 10 of the present example includes a cylindrical holder 9 having a diameter of 2.0 ± 0.2 mm and a length of 6.0 ± 0.5 mm. A quartz vibrator 5 is sealed inside the cage 9, and a lead 4 is connected to each of the connection electrodes 3. The lead 4 is guided to the outside of the cage 9 via the base ls and i s, so that power can be supplied to the crystal vibrating body 5 via the lead 4 to oscillate.

In this way, the third-order overtone crystal resonator according to the present invention is assembled, and finally, in step 28, the frequency, the equivalent series resistance Rr, which is the resistance value during vibration, and the oscillation frequency due to temperature Inspection of temperature characteristics, which is a change in equivalent series resistance, is performed. Temperature characteristics

There are many vibration modes for AT-cut crystal blanks, and the thickness vibration mode of the rectangular AT-cut crystal blank is the main vibration. Therefore, vibrations in other modes, such as sliding and bending modes, are spurious vibrations. It is important to find a side ratio that can avoid these vibrations within the operating temperature range. The frequency of each mode can be predicted by calculation. However, due to the shape and dimensions of the crystal blank, there are couplings with spurious vibrations that cannot be predicted by calculation. In particular, for a small rectangular AT-cut crystal piece manufactured as described above, a side ratio E (width w / thickness t) that can be practically used as a water crystal piece for tertiary overtone oscillation has not been found. Therefore, the applicant of the present application has made a crystal piece of various dimensions by the above-described manufacturing method and repeated the experiment to find a side ratio E without coupling with spurious vibration within the operating temperature range.

(Experimental example 1)

Fig. 7 shows the temperature characteristics of the crystal resonator manufactured by the above manufacturing method so that the side ratio E is around 12.1.8 and the frequency f oscillates at 55.0 MHz, which is the third overtone. Is shown. The length £ of the crystal blank is 4200; um, and the width w is around 1100m, and is adjusted according to the relationship of the following formula so that the frequency becomes f.

w = EX (3 XC / f) · · · (2) Figure 7 (b) shows the temperature characteristics of a crystal unit using a crystal element with a side ratio E of 12.18. The temperature characteristic of the frequency of the crystal unit draws a stable cubic curve peculiar to the AT cut, and the coupling with other vibration modes, that is, spurious vibrations, is seen in the range of 45 ° C to +95 ° C. I can't. In addition, the equivalent series resistance R r is stable at a low value of about 40 Ω, and no coupling with spurious oscillation is seen from now on. The temperature characteristics of the equivalent series resistance R r and the frequency variation (hereinafter referred to as frequency deviation) based on 25 ° C shown in the following equation were measured using a Sanders System 2100 measuring instrument. Measuring. The same applies to the following measurements. Frequency deviation = (f Τ - f 25) / f 25 · · · (3) , where the frequency at the temperature is f _T is, f ₂₅ denotes a frequency at 2 5 ° C.

Fig. 7 (a) shows the temperature characteristics of a crystal unit using a crystal piece with a side ratio E of 12.13, and Fig. 7 (c) shows the use of a crystal piece with a side ratio of 12.23. It shows the temperature characteristics of a quartz crystal resonator. These were manufactured as described above and measured by the same method. Looking at the temperature characteristics of the crystal unit with a side ratio of 12.13, coupling with spurious vibration is seen at around 125 ° C. In the case of the crystal unit with a side ratio of 12.23, Coupling with spurious vibration is seen around 95 ° C. In the range of these side ratios, there is no coupling with spurious vibration in the operating temperature range (—20 to + 80 ° C) required for the crystal oscillator, and stable oscillation is achieved. It can be seen that it can be obtained.

Fig. 8 summarizes how the applicant measured the temperature characteristics of a crystal unit using a crystal piece with a side ratio of around 12.18 by such a method, and the coupling with spurious vibrations appeared. It is. In the figure, the range where coupling with spurious vibration is seen is indicated by the solid line. As can be seen from this figure, the applicant's experiments have found that, within the operating temperature range of the crystal unit, which is within the range of 120 ° C to + 80 ° C, a region that is free from coupling with spurious vibrations can be found. did it. As shown by the dashed line in this figure, the range is the range where the side ratio E is 12.18 ± 0.05.

(Experimental example 2)

Figure 9 shows the temperature of the crystal oscillator produced by the above manufacturing method so that the side ratio E is around 8.48 and the frequency f oscillates at the third overtone of 4.1.667 MHz. The characteristics are shown. The length ί of the quartz piece in this example is 420 m, and the width w is around 120 m, and the predetermined circumference is the same as in the above example. Adjusted to get the wave number. Figure 9 (b) shows the temperature characteristics of a crystal unit using a crystal element with a side ratio E of 8.48. No coupling with other vibration modes, ie spurious vibrations, is observed at +95 ° C. The equivalent series resistance R r is also stable at a low value of approximately 50 Ω or less.

Figure 9 (a) shows the temperature characteristics of a crystal unit using a crystal piece with a side ratio E of 8.43, and Fig. 9 (c) shows the crystal oscillation using a crystal piece with a side ratio of 8.53. 4 shows the temperature characteristics of a child. These were manufactured as described above and measured by the same method. Looking at the temperature characteristics of the crystal unit with a side ratio of 8.43, coupling with spurious vibration is seen near -25 ° C. In the case of the crystal unit with a side ratio of 8.53, 80 ° C Coupling with spurious vibration is observed around C. In the range of these side ratios, there is no coupling with spurious vibration in the operating temperature range (120 to 180 ° C) required for a crystal oscillator, and stable oscillation can be obtained. You can see that. Figure 10 shows that the applicant measured the temperature characteristics of a crystal unit using a crystal piece with a side ratio of about 8.43 by such a method, and coupled it to spurious vibrations (solid line in the figure). ) Are summarized. As can be seen from the figure, the applicant's experiments have found that, within the operating temperature range of the crystal unit, that is, 20 T; did it. As shown by the dashed line in this figure, the range is such that the side ratio E is 8.48 ± 0.05.

(Experimental example 3)

Fig. 11 shows that the crystal ratio of the crystal unit manufactured by the above manufacturing method was set so that the frequency f oscillated at 71.730 MHz, which is the third overtone, with the side ratio E near 15.57 Temperature characteristics are shown. The length of the crystal piece ί is 4 2 0 0 m, and the width w is in the vicinity of 1080 m, and is adjusted so as to obtain the specified frequency as in the above example. Fig. 11 (b) shows the temperature characteristics of a crystal unit using a crystal element with a side ratio E of 1.5.77. No coupling with other vibration modes, ie spurious vibrations, is observed in the range from to +95 ° C. The equivalent series resistance R r is also stable at a low value of about 40 Ω.

Figure 11 (a) shows the temperature characteristics of a crystal unit using a crystal piece with a side ratio E of 15.50.Figure 11 (c) shows a crystal piece with a side ratio of 1.5.64. The temperature characteristics of the crystal unit used are shown. These were produced as described above and measured by the same method. Looking at the temperature characteristics of a crystal unit with a side ratio of 15.50, coupling with spurious vibration is found at around 130, and in a crystal unit with a side ratio of 15.5.64, 9 Coupling with spurious vibration is observed around 0 ° C. In the range of these side ratios, there is no coupling with spurious vibration in the operating temperature range required for the crystal unit (120 to + 80 ° C), and stable oscillation can be obtained. You can see this.

Figure 12 shows that the applicant measured the temperature characteristics of a crystal unit using a crystal piece with a side ratio of around 1.5.77 by such a method, and coupled it to spurious vibrations (see the figure). (Indicated by a solid line). As can be seen from this figure, the applicant's experiments have found a region without coupling with spurious vibrations within the operating temperature range of the crystal unit, i.e., 20 ° C to + 80 ° C. did it. The range is, as shown by the chain line in this figure, the side ratio E is in the range of 15.57 ± 0.007.

(Experimental example 4)

Figure 13 shows that the side ratio E is around 13.22, the length is 420 m, and the width is A crystal resonator adjusted so that w oscillates at 60.0 MHz with a third-order overtone when w is around 1100 m is manufactured by the above method, and its temperature characteristics are the same as in the above example The results of the measurements are summarized. As can be seen from this figure, even at this side ratio E, coupling with spurious vibrations was performed within the operating temperature range of the crystal oscillator of 120 ° C. to + 80 ° C. An area without any gaps was found. As shown by the dashed line in this figure, the range is in the range of the side ratio E of 13.2 ± 0.007.

(Experimental example 5)

Figure 14 shows that the edge ratio E is around 14.78, the length is around 4200 m, the width w is around 1110 / m, and the frequency f is 36.6. A quartz oscillator adjusted to oscillate at 7 MHz is manufactured by the above method, and the results of measuring the temperature characteristics in the same manner as in the above example are summarized. As can be seen from this figure, even at this side ratio E, the experiments performed by the applicant of the present application have shown that, with the operating temperature range of the crystal oscillator, the range of 120 ° C. to + 80 ° C. An unbonded area could be found. As shown by the dashed line in this figure, the range is the range where the side ratio E is 14.78 ± 0.07. As described above, according to the experiments performed by the present applicant, even when the crystal piece for the third overtone is reduced in size by the above-described manufacturing method, some side ratios that are not coupled to spurious vibrations are obtained. E, and its range.

Fig. 15 shows a crystal blank with these side ratios E, and in this example, a crystal blank within the range that can be stored in a cylindrical holder with a diameter of 2 mm was used. The frequency range that can be covered by the crystal unit is shown. As can be seen from this figure, the five side ratios (8.48, 12.18, 13.22) for which the coupling with spurious vibration was not observed within the operating temperature range in the present application , 14.78 15.57), the width of which exceeds approximately 30 to 90 MHz if a w of 5800 to 150 m is used. In addition, a wide range of oscillation frequencies including high frequencies can be covered without leakage.

Effect of shape on equivalent series resistance Rr

I 0

Through the above experiment, we found a range of side ratio where overtone oscillation can be performed using a small AT-cut rectangular crystal piece. Therefore, we conducted several experiments on shapes and other elements that can reduce the equivalent series resistance Rr, which is important in putting such a crystal unit using a crystal blank into practical use as a device.

5 I went.

(Experimental example 6)

Fig. 16 summarizes the measurement results of the equivalent series resistance R r of a quartz crystal element manufactured using quartz pieces with different lengths as described above. In this figure

0 is 8.48 for relatively low frequencies (f = 4 1.67 MHz) and 12.1 for intermediate frequencies (f = 55.0 MHz) as the side ratio E 8. In addition, the case of using a crystal fragment with 15.5.7 for high frequencies (f = 71.730) is shown as a representative. The width w of each crystal blank was adjusted according to the oscillation frequency.

5 Generally, a quartz crystal is designed so that the value of the equivalent series resistance Rr is about 60 Ω or less. As can be seen in Fig. 16, the side ratio E is In the case of using a 15.57 crystal piece, the length of the crystal piece should be 30000 m or more. In addition, when a crystal piece having a side ratio E of 12.18 is used, the length of the crystal piece may be at least 350 m. Furthermore, in the case of using a crystal piece having a side ratio E of 8.48, it is sufficient that the length £ of the crystal piece is 40 or more than 100 m. Therefore, the length £ of any of the crystal blanks having the side ratios found in the above experimental examples 1 to 5 is 4

When it is set to not less than 0.000 m, a crystal blank exhibiting a good equivalent series resistance Rr can be provided.

It is desirable that the length of the crystal piece be about 4700 m or less from the viewpoint that it is stored in a cylinder-shaped cage with a length of about 6 mm.

(Experimental example 7)

Fig. 17 summarizes the results of measuring the equivalent series resistance R r of a crystal unit using quartz pieces with different widths w manufactured as described above. This figure shows a crystal blank with a side ratio E of 8.48 for relatively low frequencies, 12.18 for intermediate frequencies, and 15.5.77 for high frequencies. The case where it was used is shown as a representative. The length of each crystal piece is 420 m.

As can be seen in FIG. 17, when a crystal piece having a side ratio E of 15.57 and a side ratio E of 12.18 is used, when the width w of the crystal piece is 700 m or more, If so, the equivalent series resistance R r shows a good value of 60 Ω or less. In addition, when a crystal piece with a side ratio E of 8.48 is used, the width w is 800 m or more and the equivalent series resistance R r is a good value of 60 Ω or less. Therefore, if any of the crystal blanks having the side ratios found in the above experimental examples 1 to 5 has a width w of 800 or more, a good equivalent series resistance R r Can be provided.

The width w of the crystal piece is desirably set to about 1500 m or less from the viewpoint of being accommodated in a cylinder holder having a diameter of about 2 mm.

Effect of surface roughness on equivalent series resistance R r (Experimental example 8)

Fig. 18 summarizes the measurement results of the equivalent series resistance R r of a quartz crystal element manufactured by manufacturing quartz pieces with different surface roughness after etching is completed. The side ratio E of the crystal piece was adjusted to 12.18, and the width w was adjusted so that the third overtone frequency was 55.0 MHz. The length £ of each crystal piece is 420 m. The surface roughness shown FIG. 8 is a surface roughness after the etching step 2 3-manufacturing process, described above, the maximum height R _m, the surface of the crystal piece by measuring the _x states Have confirmed. In the case of a crystal piece with a maximum height R _max of 0.1 / m, a polishing step is performed before etching, and the surface of the crystal piece is polished and finished in the same manner as before, unlike the process described above. It is. FIG. 18 shows the average value of the equivalent series resistance R r (indicated by a black circle in the drawing) and the variation of the measured value (indicated by a solid line in the drawing).

As can be seen from this figure, even if the average value of the equivalent series resistance R r is low, the variation is large depending on the crystal piece, and the equivalent series resistance R r may exceed 60 Ω even if the polishing finish is applied. Many. On the other hand, when finished by the lapping process as described above, the variation in the value of the equivalent series resistance Rr due to the crystal blank is small. Then, if the maximum value of the surface roughness _{RmaJ [of} the etched surface is _{0.2 to 0.7} zm, the equivalent series resistance R r shows a good value of about 60 Ω or less, including the range that varies from crystal to crystal. Furthermore, the maximum value of the surface roughness Rm ,, of the etched surface is 0.

If it is 3 to 0.6 m, the equivalent series resistance R r shows a very good value of 60 Ω or less including the range that varies from crystal to crystal.

(Experimental example 9)

Figure 19 shows the same measurement as in Experimental Example 8, with a crystal fragment adjusted so that the side ratio E is 8.48 and the width w is 3rd overtone frequency 41.667 MHz. The results obtained for the quartz oscillator used are summarized. Note that the length of each crystal fragment is about 4200 m.

As can be seen from this figure, even in this experimental example, even if the average value of the equivalent series resistance R r is low when polished, the variation is large depending on the crystal piece, and the equivalent series resistance R r force is 60 Ω. Many things go beyond. On the other hand, when finished by the lapping process described above, the variation in the value of the equivalent series resistance Rr due to the crystal blank is small. If the maximum value of the surface roughness Rm ,, of the etched surface is 0.2 to 0.7 _m , the equivalent series resistance Rr is about 60 Ω including the range that varies from crystal to crystal. Shows good values. Furthermore, if the maximum value of the surface roughness Rm ,, of the etched surface is 0.3 to 0.6 m, the equivalent series resistance Rr is 60 Ω or less including the range that varies from crystal to crystal. Shows very good values.

(Experimental example 10)

Figure 20 shows the same measurement as in Experimental Example 8, with the quartz piece adjusted so that the side ratio E is 15.57 and the width w is 31.7% of the triplet frequency. The results obtained for a quartz crystal unit using are summarized. The length £ of each crystal piece is 420 m. As can be seen from this figure, even in this experimental example, even if the average value of the equivalent series resistance R r was low when polishing was applied, the variation due to the crystal piece was large, and the equivalent series resistance R r force was 60 Ω. There are many things that go beyond. On the other hand, when finished by the lapping process described above, the variation in the value of the equivalent series resistance Rr due to the crystal blank is small. If the maximum value R _max of the surface roughness of the etched surface is from 0.2 to 0. An equivalent series resistance R r is approximately 6 0 Omega below, including the range varies for each crystal piece and good value Show. Furthermore, if the maximum surface roughness _{Rma! T of} the etched surface is 0.3 to 0.6 m, the equivalent series resistance Rr is 60 Ω or less, including the range that varies from crystal to crystal. And very good values. As a result of such experiments conducted by the present applicant, the value of the equivalent series resistance Rr itself was small, and the variation of this value Rr was small for each crystal blank. In order to obtain such a crystal resonator, it has been found that it is desirable not to finish the surface of the crystal blank as smoothly as possible, but to finish it to a certain roughness within the range obtained above.

Conventionally, when manufacturing relatively small crystal blanks, especially crystal blanks that vibrate overtones, polishing is performed in order to suppress the irregular reflection of vibrations on the surface of the crystal blank and improve the excitation efficiency. However, the surface roughness was made as small as possible. Therefore, the surface roughness of the surface of the crystal blank was finished to a maximum height R _{mai [} of _0.2 or _0.1 m or less. In particular, polishing was thought to be indispensable because vibrations tended to leak when the quartz pieces were made smaller.

Polishing is a laborious and costly operation using expensive polishing agents. In addition, the surface can be polished Even if the roughness decreases, it is difficult to maintain the flatness of the surface, and the surface will undulate. Polishing is a work that requires such skill, and polished quartz pieces are difficult to peel off when the polished planes come into close contact with each other, and the polished surface is trivial. There is also difficulty in handling such as scratching and deterioration of surface roughness. In contrast, in the present invention may be finished by lapping, the maximum height R _m of surface roughness of the crystal piece, _x is from 0. 2 ~ 0. 7 m , is desirable properly 0.3 to 0 With a distance of 6 m, a crystal resonator with a low equivalent series resistance Rr can be obtained, and at the same time, a crystal resonator with little variation among crystal pieces, that is, a good yield can be obtained. When manufacturing a crystal blank that forms such a high-performance and high-yield crystal resonator, there is no need to perform policing, and therefore, it is necessary to produce a crystal blank, especially a small crystal blank. This eliminates the need for costly, labor-intensive, and polishing processing, and can provide a high-performance quartz resonator at low cost.

FIG. 21 shows an enlarged distribution state of the equivalent series resistance R r of a crystal unit using a crystal piece having a side ratio E of 12.18 measured in Experimental Example 8. When the polished surface is etched to have a maximum surface roughness of about 0.1 m, the average equivalent series resistance R r is as low as 38 Ω, but the maximum equivalent series resistance R r Some quartz resonators have a resistance of about 100 Ω. On the other hand, if the lapping surface is etched and the maximum height of the surface roughness is about 0.4 m, the average equivalent series resistance Rr shows a good value of 40 Ω, Furthermore, the maximum value of the equivalent series resistance R r is as good as about 50 Ω.

Since the thickness of a polished crystal piece has a large distribution, it is necessary to adjust the frequency by etching. In addition, the polished surface is easily stained and scratched during the peeling, washing and drying processes. No. Therefore, when such a surface is etched, a dirty portion remains as a pit without being etched, that is, a so-called etch pit is generated. In addition, scratches and the like are enlarged, resulting in a surface with uneven unevenness. As a result, the equivalent series resistance Rr increases.

In contrast, after lapping, when the etching, R _{ma it} is rather small and uniform surface roughness can be obtained. For this reason, the variation of the equivalent series resistance Rr is small, and a crystal blank with a high yield can be obtained. This applies not only to the crystal blank but also to other ceramic resonators that reflect and confine vibrations on the surface of the element.

The frequency distribution of the lap-finished quartz piece is also small because the polished quartz piece has a small thickness distribution. In the case of lapping, the equivalent series resistance does not vary even when etched, so the wrapped quartz pieces are classified by resonance frequency, the etching time is determined for each classification, and the frequency is further narrowed by etching. It can be confined to a range.

(Experimental example 1 1)

Figure 22 shows the change in surface roughness with the amount of etching when the lap-finished quartz piece is etched. FIG. 23 shows a change in the equivalent series resistance Rr value according to the amount of etching. The side ratio E of the crystal piece was 12.18, and the width w was adjusted so as to oscillate at a frequency of 55.0 MHz. The length £ of the crystal piece is 420 m. In addition, FIGS. 22 and 23 show that the surface roughness immediately before the etching is a crystal piece with a maximum height R _{ma J [of 1.2} m, a crystal piece B with a 0.7 m thickness, and a crystal piece B with a maximum height of _0.7 m. The change in surface roughness and the change in equivalent series resistance R r of a 4 m crystal blank C are shown. The value of the equivalent series resistance R r is The average of multiple measurements is shown. As described above, the etching liquid uses 10 to 30 weight percent hydrofluoric acid.

As can be seen from Fig. 22, the maximum height R _max of the surface roughness sharply decreases until the etching processing amount is about 0.5 m, and the part of the damaged layer that is most roughened by lapping It is presumed that the surface was etched away. No significant change in surface roughness was observed between 0.5 and 2. Etching amount, indicating that the affected layer with a stable structure was reduced by etching. On the other hand, when the amount of etching exceeds 2.5 m, the maximum height R _m , _x of the surface roughness increases. This is thought to be due to the effect that the etching rate differs depending on the direction due to the anisotropy of the quartz single crystal. Due to the anisotropy of the etching speed, large irregularities are generated on the surface of the crystal blank.

It is determined that R ca x has increased.

The change in the equivalent series resistance shown in Fig. 23 also shows almost the same tendency as the maximum surface roughness _{Rma! T} shown in Fig. 22. That is, the equivalent series resistance R r sharply decreases until the etching amount is 0.5 m, and there is no significant change in the equivalent series resistance R r when the etching amount is 0.5 to 2.5 m. I can't. When the amount of etching exceeds 2.5 m, the tendency of the equivalent series resistance Rr to increase becomes remarkable. Thus, in this experiment, in order to obtain a crystal piece having a low and stable equivalent series resistance Rr value, it is preferable to set the etching amount after lapping to 0.5 to 2.5 m. You can see that. If the thickness reduction on one side due to the etching process falls within this range, structurally stable portions of the deformed layer formed when lapping or cutting the crystal blank appear on the surface of the crystal blank. It is considered that a good equivalent series resistance Rr can be obtained.

Furthermore, as can be seen in Fig. 23, a good equivalent series resistance R of less than 60 Ω In order to obtain r value, the crystal blank shown in this diagram desirable to keep the maximum height R _ma, the surface roughness of the pre-etching 0. 7 m or less arbitrarily. Considering the degree of surface roughness that can be achieved by lapping, in order to manufacture a crystal blank with good equivalent series resistance Rr, the maximum height of the surface roughness of the crystal blank before etching is required. It was found in this experiment that R ma, should be in the range of 0.3 to 0.7 ^ m. In this example, an alumina-based abrasive having an average grain size of 2.5 to 3.0 m was used in order to lap the surface roughness of the crystal blank within the above range. Influence of Electrodes In order to form electrodes on a crystal blank and obtain a crystal resonator with good characteristics, it is important to properly select the size and thickness of the electrodes. If the electrode is small, energy confinement will be insufficient and the equivalent series resistance Rr will increase, while if the electrode is formed up to the end of the crystal blank, spurious vibrations at the end will be induced. This causes the temperature characteristics to deteriorate and the equivalent series resistance Rr to increase. In particular, the relationship between the size and thickness of the electrode and the equivalent series resistance Rr has not been investigated for a small crystal piece that vibrates with the third overtone as in this example.

(Experimental example 1 2)

Fig. 24 shows a quartz piece with a side ratio of 12.18, width w of 1109 m, length of 420 m and 55.0 MHz manufactured by the above method. This shows the temperature characteristics when electrodes of different sizes are deposited. As described above with reference to FIG. 3, electrodes are formed on both sides of the crystal blank. In this example, the electrodes are formed by depositing chromium and silver. We prepared several samples with different distances D between the width direction edge of the crystal blank and the electrode width direction, and used them to measure the temperature characteristics of the crystal unit manufactured by Sanders. The measurement was performed using an instrument system 2100.

As shown in Fig. 24 (b), when the distance D is 100 m, the frequency deviation is stable over the entire measured temperature range, and the cubic curve which is the characteristic of the AT-cut crystal resonator Is drawing. In addition, the equivalent series resistance R r is stable over the entire temperature range, and its value is good at around 40 Ω. On the other hand, as shown in Fig. 24 (a), when the distance D is 350 m, both the frequency deviation and the equivalent series resistance Rr are unstable over the entire measured temperature range. This phenomenon is thought to be caused by insufficient energy confinement due to the small electrode area. On the other hand, as shown in Fig. 24 (c), when the distance D is 50 m, coupling with spurious vibration is seen near 80.

FIG. 27 summarizes the maximum value of the equivalent series resistance R r at a temperature of 20 to + 80 ° C. measured by changing the interval D from 50 to 350 m. In the case where the side ratio E of this example is 12.18, it can be seen that the interval D is preferably 50 to 340 m in terms of the equivalent series resistance R r and the power of 60 Ω or less. Then, as shown above, when the interval D is 50! / M, the coupling with spurious vibration is within the operating temperature range, so that it is understood that the interval D is desirably 75 to 340 m.

(Experimental example 13)

Fig. 25 shows the same results as in the above experiment using a quartz piece with a side ratio of 8.48, a width w of 94.4 m, and a length £ of 420 m and 45.0 MHz. The result of the measurement is shown. As shown in Fig. 25 (b), the interval D In the case of 100 m, the frequency deviation and the equivalent series resistance R r are stable over the entire temperature range, and the values are also good at around 50 Ω.

On the other hand, as shown in Fig. 25 (a), when the interval is 250 m, the temperature is unstable over the entire temperature range, and the same as in the previous experimental example. Further, as shown in FIG. 25 (c), when the distance D is 50 m, coupling with spurious vibration is observed at around 80 ° C.

Fig. 27 summarizes the maximum value of the equivalent series resistance R r at _20 .- + 80 when the interval D is varied from 50 to 250 m. When the side ratio E of this example is 8.48, the interval D is preferably 50 to 230 m in terms of the equivalent series resistance R r of 60 Ω or less. Then, as shown above, when the distance D is 50 m, the coupling with the spurious vibration is within the operating temperature range, so that it is understood that the distance D is desirably 75 to 230 μm.

(Experimental example 14)

Figure 26 shows the above-mentioned results using a crystal piece with a side ratio of 15.57, a width w of 1170 m, and a length 4 of 4200 m and a size of 6.6.667 MHz. The results of the same measurements as in the experiment are shown. As shown in Fig. 26 (b), when the interval D is 100 m, the frequency deviation and the equivalent series resistance R r are stable over the entire temperature range, and their values are very close to 40 Ω. It is good.

On the other hand, as shown in Fig. 26 (a), when the distance D is 350 m, the temperature is unstable over the entire temperature range, and the same as in the previous experimental example. In addition, as shown in FIG. 26 (c), when the distance D is 50 m, coupling with spurious vibration is observed around 35 ° C.

Figure 27 shows the equivalent direct current measured while changing the distance D from 50 to 350 m. The maximum value of the column resistance Rr at 20 to 180 is summarized. In the case of this ^ with a side ratio E of 15.5.77, it can be seen that the interval D should be 50 to 340 in terms of the equivalent series resistance R r of 60 Ω or less. Then, as shown above, when the interval D is 50 m, the coupling with the spurious vibration is within the operating temperature range, so that it is understood that the interval D is desirably 75 to 340 m.

In this way, when the electrodes are formed on the crystal blank, if the interval D is set under the above conditions, the equivalent series resistance R r is further reduced, excluding the influence of spurious vibrations caused by the ends of the crystal blank. Can be lower. That is, in the low frequency side ratio of 8.48, the interval D is desirably 75 to 230 m. When the side ratio is 12.18 to 15.5.7, the distance D is preferably 75 to 340 m. In addition, if the interval D is set to 75 to 200 / m, the frequency deviation of the crystal resonator with a low frequency side ratio of 8.48 to a high frequency side ratio of 15.5.7 will be reduced. It is stable and can provide a sufficiently low equivalent series resistance.

(Experimental example 15)

Figure 28 shows a quartz piece with a side ratio of 12.18, width w of 1109 m, and length H of 420 m, manufactured by the above method, and electrodes deposited on it. This shows the relationship between the amount of change in frequency, which varies depending on the amount of vapor deposition, and the equivalent series resistance Rr when a quartz resonator is manufactured. The frequency change is expressed by the following equation.

Frequency change = (f-f *) / f

Here, f is the frequency when no evaporation is performed, and Γ is the frequency when evaporation is performed. As can be seen from the figure, the equivalent series resistance Rr is very high when the amount of change in frequency when the electrode is deposited is less than 700 ppm. When the frequency change is in the range of 700 to 300 pm, the equivalent series resistance Rr is stable at a good value of about 50 Ω. On the other hand, when the amount of change in the frequency when the electrode is deposited exceeds 300 000 ppm, the equivalent series resistance Rr tends to increase, and it can be seen that the characteristics of the crystal resonator are deteriorated. When the frequency change is 700 ppm or less, the value of the equivalent series resistance Rr is high due to insufficient energy confinement of the thickness-shear vibration, and 300 ppm or more. When, the weight of the excitation electrode is too large, which inhibits the thickness shear vibration of the crystal blank, and the equivalent series resistance Rr is considered to have increased.

As described above, if the variation of the frequency of the crystal blank during electrode deposition is kept within the range of 700 ppm to 300 ppm by the measurement of this example, a good equivalent series resistance R r Can be provided. As described above, according to the experiments and measurements of the applicant, for example, the diameter

It has been found that it is possible to provide a crystal resonator having a cylinder of about 2 mm and a length of about 6 mm, which can cover an oscillation frequency of around 100 MHz. The crystal blank, crystal vibrator, and crystal vibrator having each element in the range of the numerical values clarified above have an AT cut within the operating temperature range of −20 ° C to + 80 ° C. It has a stable temperature characteristic peculiar to a quartz crystal resonator, and the equivalent series resistance R r is a good value of about 60 Ω or less.

FIG. 29 shows a crystal unit 30 in which the crystal unit 10 of this example is molded with resin and surface-mounted. This crystal oscillator 30 A lead 4 protruding from a cylindrical holder 9 of a crystal oscillator 10 is welded to a metal lead 31 and molded with a resin 32. The crystal oscillator 30 of this example is an element that can be mounted on the surface of the substrate as it is because the cage 9 is molded with the resin 32.

FIG. 30 shows a crystal oscillator 40 in which the crystal unit 10 of the present example and the IC integrated circuit 41 are combined and molded with resin. In this crystal oscillator 40, a crystal oscillator 10 and an IC integrated circuit 41 at least including an oscillation circuit for oscillating the crystal oscillator 10 with a third overtone are mounted on a metal frame 42. Mounted with resin 32. By mounting the device 40 on a substrate, a reference frequency that regulates the operation of each circuit mounted on the substrate can be supplied. Since the diameter of the crystal unit 10 in this example is as small as about 2.0 mm, the thickness of the oscillator is also from 2.5 mm to 2.7 mm, and the size and weight can be extremely reduced. Further, by using the crystal resonator of the present example, a high frequency can be stably supplied, so that the oscillator is suitable for an electronic device with a high-speed operation.

As described above, the quartz piece having the side ratio found by the present invention can oscillate with a third overtone without coupling with spurious vibration even in a region having a very small size. A thin crystal blank can be obtained. Further, according to the present invention, when such a small-sized rectangular AT crystal blank capable of overtone oscillation is used, the equivalent series resistance with respect to the crystal blank or the crystal vibrator shows a good value. To find various elements for Therefore, the use of the crystal blank according to the present invention provides a crystal resonator and a crystal oscillator that can be reduced in size and weight so that they can be used as SMDs like ICs, and that can oscillate high frequencies. It is possible to do. Furthermore, such an excellent The present invention also discloses a manufacturing method for providing a crystal piece having excellent characteristics at a high yield. According to the present invention, various electronic devices such as communication devices and information processing devices, which will become lighter, smaller, and faster in the future. It is possible to provide a crystal oscillator and a crystal oscillator suitable for the equipment field. INDUSTRIAL APPLICABILITY The crystal blank, crystal resonator, crystal resonator, and crystal oscillator according to the present invention can be used in various electronic device fields such as communication devices and information processing devices. Can be used as a reference clock source. In particular, the quartz oscillator according to the present invention and the quartz oscillator using the same are capable of providing a small, lightweight, high-frequency clock signal.

It can be provided as an SMD product that can oscillate a stable high frequency in the field of miniaturized electronic devices.

Claims

The scope of the claims

1. A crystal with an XY'Z 'axis rotated about the X axis on a rectangular coordinate system where the electric axis is the X axis, the mechanical axis is the Y axis, and the light axis is the Z axis.

5 A rectangular AT-cut crystal blank cut out of a single crystal for a third-order overtone crystal resonator, having a thickness t in the Y′-axis direction and a width w in the Z ′ 轴 direction. The range of the side ratio wZt defined by the width w and the thickness t is 8.48 ± 0.05, 12.18 ± 0.05, 13.22 ± 0.07 , 14.78 ± 0.07, 15.77 ± 0.07, α.

2. The rectangular AT chip J crystal piece according to claim 1, having a length ^ in the X-axis direction, wherein the length ^ is in a range of 400-470. .

Fifteen

3. The rectangular AT cut crystal according to claim 2, wherein the range of the width w is 800 to 150.

4. The rectangular AT cutter according to claim 1, characterized in that the surface has an etched surface, and the maximum surface roughness of the surface thereof ranges from 0.2 to 0.7 m. Crystal piece.

5. In claim 4, wherein the maximum height R _ma surface roughness of the surface, the range of 0.3 to 0. Rectangular AT cut water 5, which is a 6 m B曰片o

6. The rectangular AT-cut quartz piece having a side ratio w / t of 8.48 ± 0.05 according to claim 1 and the thickness t of the rectangular AT-cut quartz piece are defined as follows. A quartz vibrating body having an electrode attached to a surface facing each other, wherein a width W of the electrode along the Z ′ axis is smaller than a width w of the rectangular AT-cut quartz piece, and a width W direction of the electrode. A quartz vibrating body, characterized in that the distance between the end of the rectangular AT-cut crystal side and the end in the direction w of the rectangular AT-cut water crystal is 75 to 230 m.

7. The crystal resonator according to claim 6, wherein the interval is 75 to 200 zm.

8. The range of the side ratio w / t according to claim 1 is 12.18 ± 0.05, 13.22 ± 0.07, 14.78 ± 0.07, and 15.5 7 Sat 0.07 A rectangular AT-cut crystal blank of any one of 0.07 and an electrode attached to the surface facing the rectangular AT-cut crystal blank across the thickness t. A quartz vibrator, wherein the width W of the electrode along the Z 'axis is smaller than the width w of the rectangular AT-cut quartz piece, the end in the width W direction of the electrode and the rectangular AT-cut quartz side. A quartz vibrator characterized in that the width between the ends in the w direction is 75 to 340 / m.

9. The crystal resonator according to claim 8, wherein the interval is 75 to 200 m.

10.A quartz vibrator comprising: the rectangular AT-cut quartz piece according to claim 1; and electrodes formed on opposite surfaces of the rectangular AT-cut quartz piece with the thickness t interposed therebetween. The amount of film formation of the electrode is A quartz vibrating body characterized in that the amount is 700,000 to 300,000 ppm in terms of a change in frequency of the rectangular AT-cut quartz piece.

1 1. A rectangular AT-cut quartz piece according to claim 1, and electrodes provided on two faces facing each other across the thickness t of the rectangular AT-cut quartz piece.

A supporting mechanism for supporting one end of the rectangular AT-cut quartz crystal piece in the X-axis direction, wherein the supporting mechanism has the electrodes joined by solder or conductive adhesive. A crystal unit characterized by having a lead.

1 2. A crystal resonator comprising: the rectangular AT-cut crystal piece according to claim 1; and a crystal retainer for protecting the rectangular AT-cut crystal piece, wherein the crystal retainer has a diameter. A crystal unit having a range of 2.0 ± 0.2 mm and a length range of 6.0 ± 0.5 mm.

1 3. The method according to claim 12, wherein the width w of the rectangular flat AT-cut quartz piece is 800 to 150 ^ m, and the length along the X-axis direction is 40. A quartz resonator having a length of from 0 to 470 m.

14. The crystal unit according to claim 12, wherein the crystal holder is molded by a molding member.

15. A quartz crystal holder comprising: a crystal holder for storing and protecting the rectangular AT-cut crystal piece according to claim 1; and an integrated circuit device including an oscillation circuit of the rectangular AT-cut crystal piece. A crystal oscillator, wherein a cage and an integrated circuit device are molded together by a molding member.

16. The crystal oscillator according to claim 15, wherein the crystal retainer has a diameter range of 2.0 ± 0.2 mm and a length range of 6.0 ± 0.5 mm. .

1 7. The method according to claim 15, wherein the range of the width w of the rectangular AT-cut quartz piece is 800 to 150 m, and the range of the length along the X-axis direction is 400. A quartz oscillator having a length of 0 to 470 m.

1 8. A method for manufacturing a crystal blank for a crystal vibrating body, which is subjected to a lapping process on a surface of a wafer cut out of a crystal, followed by an etching process, wherein a polishing material is used to finish the surface immediately before the etching process. A method of manufacturing a crystal piece, wherein the method is performed by the wrapping method.

1 9. A method for manufacturing a crystal blank for a crystal vibrating body, which is processed by lapping the surface of the AT cut of the AT cut out of the crystal, followed by etching. Characterized in that the length is 0.5 to 2.5 m.

20. The maximum height of the surface roughness of the surface immediately before the etching process according to claim 19.

The method for manufacturing a crystal blank, wherein the range of 0.3 to 0.7 m is set.

21. The method according to claim 20, wherein in the lapping processing for finishing the surface immediately before the etching processing, an alumina-based abrasive having an average grain diameter of 2.5-3 m is used. How to make crystal blanks Law.

22. The method for manufacturing a crystal piece according to claim 19, wherein, in the etching, 10 to 30% by weight of hydrofluoric acid is used as an etching solution.

2 3. The method for manufacturing a quartz vibrator, comprising a film forming step of forming a metal electrode material on each surface of the quartz crystal piece of the AT cut opposed in the thickness direction and forming electrodes. The method for manufacturing a crystal resonator according to claim 1, wherein the amount of change in the frequency of the crystal piece is 700 to 300 ppm.