JP3885578B2 - Method for manufacturing piezoelectric resonator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a piezoelectric resonator and a ladder filter using a spreading mode, and more specifically, an improved frequency selection process for obtaining individual piezoelectric resonators from a plurality of mother piezoelectric substrates. The present invention relates to a method for manufacturing a piezoelectric resonator and a ladder type filter.
[0002]
[Prior art]
For example, Japanese Patent Application Laid-Open No. 10-190388 discloses a method for suppressing a decrease in yield due to frequency variations when manufacturing a piezoelectric resonator. As shown in FIG. 7, in the method described in this prior art, after a piezoelectric ceramic plate is prepared, electrodes are printed and baked on both surfaces, and then the piezoelectric ceramic plate is polarized. Next, the frequency of the polarization-processed piezoelectric ceramic plate is measured, and a first selection step is performed in which the frequency is largely deviated from the target value. Next, after polishing the electrodes used for polarization, electrodes for individual piezoelectric resonators are formed by vapor deposition. Thereafter, the piezoelectric ceramic plate is cut in the thickness direction, and individual piezoelectric resonators are obtained. The frequency of the obtained piezoelectric resonator is measured, and the second selection process is performed.
[0003]
A piezoelectric resonant component, a piezoelectric filter, or the like is assembled using a good piezoelectric resonator that belongs to the target frequency range in the second sorting step. On the other hand, with respect to the piezoelectric resonator deviated from the target frequency range in the frequency selection process, the frequency is finely adjusted by performing electrolytic plating for a time proportional to the difference with respect to the unnecessary frequency and increasing the electrode thickness. . Thereafter, the assembly of the piezoelectric resonant component or the like is performed using the piezoelectric resonator whose frequency is adjusted to the target frequency range. Then, final characteristic selection of the piezoelectric resonant component obtained in this way is performed.
[0004]
[Problems to be solved by the invention]
As described in the prior art described above, conventionally, when obtaining a piezoelectric resonant component, a piezoelectric filter, or the like, each piezoelectric resonator is obtained by cutting a mother piezoelectric substrate. In this case, the mother piezoelectric substrate is cut so that each piezoelectric resonator has the same dimension. Since the piezoelectric resonator obtained by cutting has a large frequency variation as described above, a complicated characteristic process must be performed, and a complicated frequency correction process that increases the electrode thickness must be performed. did not become. In addition, since the frequency variation is large, it is difficult to correct the frequency to the target frequency range in the piezoelectric resonator located at the bottom of the frequency distribution of the obtained many piezoelectric resonators. Therefore, the proportion of discarded piezoelectric resonators must be increased.
[0005]
The object of the present invention is to eliminate the above-mentioned disadvantages of the prior art, simplify the frequency selection process in obtaining individual piezoelectric resonators using the spreading mode from the mother piezoelectric substrate, and increase the yield rate. An object of the present invention is to provide a method of manufacturing a piezoelectric resonator that can be enhanced.
[0006]
Another object of the present invention is a method of manufacturing a ladder type filter in which a series resonator and a parallel resonator are constituted by piezoelectric resonators using a spreading mode, in which a piezoelectric resonator is obtained from a mother piezoelectric substrate. An object of the present invention is to provide a method for manufacturing a ladder type filter that can simplify the frequency selection process just before and can increase the yield rate of piezoelectric resonators.
[0007]
[Means for Solving the Problems]
A first invention of the present application is a method of manufacturing a piezoelectric resonator using a spreading mode in which vibration electrodes are formed on both surfaces of a piezoelectric substrate, the step of preparing a mother piezoelectric substrate, A step of forming electrodes on both main surfaces, a step of measuring the resonance frequency or anti-resonance frequency of the mother piezoelectric substrate on which the electrodes are formed, and a target frequency value of the resonance frequency or anti-resonance frequency. Obtaining individual piezoelectric resonators by cutting the mother piezoelectric substrate so as to increase or decrease the cut dimensions for obtaining the individual piezoelectric resonators according to the magnitude of the positive or negative deviation; and Measuring the resonance frequency or anti-resonance frequency of each piezoelectric resonator manufactured from a plurality of mother piezoelectric substrates, and selecting the characteristics.
[0008]
A second invention of the present application is a method of manufacturing a ladder type filter in which a series resonator and a parallel resonator are configured by a piezoelectric resonator using a spreading mode in which vibration electrodes are formed on both surfaces of a piezoelectric substrate. Preparing a plurality of first mother piezoelectric substrates and a plurality of second mother piezoelectric substrates; forming electrodes on both surfaces of the first and second mother piezoelectric substrates; Measuring the resonance frequency of the plurality of first mother piezoelectric substrates on which the electrodes are formed and the anti-resonance frequency of the plurality of second mother piezoelectric substrates on which the electrodes are formed; , By cutting the second mother piezoelectric substrate by changing the cutting dimension according to the frequency difference between the measured resonance frequency or anti-resonance frequency and the target resonance frequency or anti-resonance frequency, respectively. 1st and 2nd pressure respectively Obtaining a resonator, measuring a resonance frequency of the first piezoelectric resonator and an anti-resonance frequency of the second piezoelectric resonator, and selecting characteristics of the first and second piezoelectric resonators; And a step of manufacturing a ladder filter by combining the selected first and second piezoelectric resonators as a series resonator and a parallel resonator, respectively.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be clarified by describing specific examples of the present invention.
[0010]
With reference to FIGS. 1-5, the manufacturing method of the ladder type filter as one Embodiment of this invention is demonstrated.
The ladder filter obtained in this embodiment has a circuit configuration shown in FIG. As shown in FIG. 2, series resonators S <b> 1 and S <b> 2 are connected to a series arm between the input terminal 1 and the output terminal 2. In addition, three parallel arms are formed between the series arm and the ground potential, and parallel resonators P1, P2, and P3 are arranged on the three parallel arms, respectively.
[0011]
In the ladder filter obtained in the present embodiment, the series resonators S1 and S2 and the parallel resonators P1 to P3 are configured by piezoelectric resonators using a spreading mode.
[0012]
In the manufacture, first, as shown in FIG. 1, a mother piezoelectric substrate is prepared. The mother piezoelectric substrate is made of piezoelectric ceramics such as lead zirconate titanate ceramics and is polarized in the thickness direction.
[0013]
In this case, in order to obtain a ladder-type filter, a plurality of first mother piezoelectric substrates and a plurality of second mother piezoelectric substrates are prepared. The first mother piezoelectric substrate is prepared to obtain a first piezoelectric resonator for forming a series resonator, and the second mother piezoelectric substrate is a second for forming a parallel resonator. Prepared to obtain a piezoelectric resonator. The thickness of the second piezoelectric substrate is thicker than that of the first mother piezoelectric substrate.
[0014]
Next, after electrodes are formed on both surfaces of the first and second mother piezoelectric substrates by vapor deposition or the like, the frequency measurement process shown in FIG. 1 is performed by the control device 11 and the frequency measurement device 12 shown in FIG. It is done using. Next, by patterning the entire surface electrode, vibration electrodes for individual piezoelectric resonators are formed. As representatively shown in FIG. 4 as the first mother piezoelectric substrate 3, a plurality of vibration electrodes 4 are formed on the upper surface of the mother piezoelectric substrate 3. Similarly, a plurality of vibration electrodes are formed on the lower surface of the piezoelectric substrate 3 so as to face the vibration electrodes 3. Similarly, in the second mother piezoelectric substrate, vibration electrodes for individual piezoelectric resonators are formed in a matrix on both main surfaces.
[0015]
Thereafter, a cutting / resonator manufacturing step and a resonator combination step are performed using the cutting device 13 shown in FIG. 5 to a size corresponding to the frequency of the mother piezoelectric substrate.
First, according to a command from the control device 11, the frequency measuring device 12 measures the frequency of the piezoelectric substrate of the first or second mother on which the entire surface electrode is formed. In this case, the resonance frequency of the piezoelectric resonator formed on the first mother piezoelectric substrate is measured, and the anti-resonance frequency is measured in the case of the second mother piezoelectric substrate.
[0016]
As the frequency measuring device 12, an appropriate frequency measuring device such as a network analyzer is used as shown in FIG. As shown in FIG. 6A, preferably, the frequency of each mother piezoelectric substrate 3 is changed to a frequency measuring device 12 such as a network analyzer while the plurality of mother piezoelectric substrates 3 are conveyed in the direction of arrow A. Is measured.
[0017]
The resonance frequency or anti-resonance frequency measurement value obtained as described above is given to the control device 11. The control device 11 classifies the mother piezoelectric substrate based on the measured resonance frequency or anti-resonance frequency obtained as described above. That is, the control device 11 stores a plurality of resonance frequency ranges or a plurality of anti-resonance frequencies in advance. Whether or not the measurement value belongs to the plurality of resonance frequency ranges or anti-resonance frequency ranges is determined and classified. According to the classification of the control device 11, the measured mother piezoelectric substrate 3 is stored in the classification cassettes 21 to 26 as shown in FIG. In each of the classification cassettes 21 to 26, a plurality of mother piezoelectric substrates belonging to the same resonance frequency measurement range or anti-resonance frequency range are stacked.
[0018]
Next, preferably, as shown in FIG. 6B, the mother piezoelectric substrate 3 or the mother piezoelectric substrate 4 is transferred from the classification cassettes 21 to 26 to the classification trays 31 to 36. In the classification trays 31 to 36, a plurality of mother piezoelectric substrates are arranged without overlapping each other. A plurality of mother piezoelectric substrates stored in the classification cassette 21 are transferred to the classification tray 31. Similarly, a plurality of mother piezoelectric substrates stored in the classification cassettes 22 to 26 are transferred to the classification trays 32 to 36, respectively.
[0019]
Thereafter, an adhesive sheet 42 is provided on the lower surface of the classification tray 31 so as to schematically show a state where one mother piezoelectric substrate is arranged on the classification tray on the right side of FIG. 6B. The cutting and peeling tray 41 is stacked, and the mother piezoelectric substrate 3 is bonded to the adhesive sheet 42.
[0020]
The control device 11 stores in advance the target frequencies of the first and second piezoelectric resonators, that is, the resonance frequency or the anti-resonance frequency.
The control device 11 calculates a cutting dimension for cutting the mother piezoelectric substrate according to the difference between the measured value of the resonance frequency or the anti-resonance frequency and the target value. In this case, when the measured value of the resonance frequency is higher than the target resonance frequency, the cutting dimension is selected so that the rectangular planar shape of each piezoelectric resonator becomes large. Conversely, when the measured resonance frequency is lower than the target resonance frequency, the cutting dimension is determined so that the planar shape of each piezoelectric resonator is reduced. This cutting dimension is determined in accordance with the target resonance frequency and the measured resonance frequency.
[0021]
Similarly, when cutting the second mother piezoelectric substrate, similarly, the difference between the measured antiresonance frequency of each piezoelectric resonator measured on the second mother piezoelectric substrate and the target antiresonance frequency value. Accordingly, the mother piezoelectric substrate is cut.
[0022]
When cutting, the cutting and peeling tray 41 is cut using a cutting device such as a dicer while the first and second mother piezoelectric substrates are bonded to each other via the adhesive sheet 42. In this case, the classification trays 31 to 36 are removed.
[0023]
Next, after the mother piezoelectric substrate is cut to obtain individual piezoelectric resonators, the individual piezoelectric resonators are separated from the adhesive sheet 42 and taken out.
As described above, the first piezoelectric resonator 6 shown in FIG. 3 is obtained. The piezoelectric resonator 6 includes a piezoelectric substrate 7 obtained by cutting the mother piezoelectric substrate 3, a vibrating electrode 3 formed on the upper surface of the piezoelectric substrate 7, and a vibrating electrode (not shown) formed on the lower surface. And have. In the present embodiment, the vibration electrode 3 is formed on the upper surface of the piezoelectric substrate 7 so as not to reach the outer peripheral edge, but may be formed so as to reach the outer peripheral edge. However, when the vibrating electrode 3 is formed so as to reach the outer peripheral edge of the piezoelectric substrate 7, the electrodes are formed on the entire surface of the piezoelectric substrate when the electrodes are formed on the piezoelectric substrates of the first and second mothers. Therefore, the resonance frequency or anti-resonance frequency of each piezoelectric resonator cannot be measured at the mother piezoelectric substrate stage. Therefore, in that case, the resonance frequency or anti-resonance frequency of the structure in which the electrode is formed on the entire surface of the mother piezoelectric substrate is measured, and the control device 11 has the resonance frequency target value or anti-resonance frequency in the mother piezoelectric substrate. The target value only needs to be stored in advance.
[0024]
Returning to FIG. 1, as described above, the frequency of the piezoelectric resonator using each spreading mode is measured at the mother piezoelectric substrate stage, and the obtained frequency measurement value and the target resonance frequency or anti-resonance are obtained. Depending on the difference from the frequency, the mother piezoelectric substrate is cut to obtain individual piezoelectric resonators.
[0025]
In this case, the first piezoelectric resonator is obtained from the first mother piezoelectric substrate, and the second piezoelectric resonator is obtained from the second mother piezoelectric substrate.
Thereafter, the first and second piezoelectric resonators obtained as described above are combined as a series resonator and a parallel resonator, respectively, and connected so as to constitute the ladder type circuit shown in FIG. Thus, a ladder type filter is obtained.
[0026]
In the manufacturing method of the present embodiment, when the first and second piezoelectric resonators are obtained by cutting from the first and second mother piezoelectric substrates, the cutting dimensions are determined according to the deviation of the frequency of the piezoelectric resonator from the target frequency. Is determined. Therefore, frequency variations in the first and second piezoelectric resonators obtained by cutting are reliably reduced. Therefore, in the step of combining the first and second piezoelectric resonators shown in FIG. 1, the frequency of the obtained first and second piezoelectric resonators is measured, and a simple frequency selection step is performed when combining them. Thus, it is possible to provide a ladder type filter with little characteristic variation.
[0027]
Moreover, since the frequency variation of the obtained piezoelectric resonator is reduced by changing the cutting dimension when the mother cuts from the piezoelectric substrate, the yield rate of the piezoelectric resonator can be effectively increased.
[0028]
In addition, even when many first piezoelectric resonators are obtained from a plurality of first mother piezoelectric substrates, characteristic variations among the mother piezoelectric substrates can be absorbed by changing the cutting dimensions. Therefore, it is possible to reliably obtain a piezoelectric resonator with little frequency variation from a large number of mother piezoelectric substrates.
[0029]
In the above embodiment, the first and second piezoelectric resonators for forming the series resonator and the parallel resonator are taken out from the first and second mother piezoelectric substrates, and the combined ladder filter is manufactured. However, the present invention can be applied not only to the ladder type filter but also to the manufacture of a piezoelectric filter using another spreading mode or a piezoelectric resonant component using only a single piezoelectric resonator. That is, when manufacturing a piezoelectric resonant component using a single piezoelectric resonator, in the above embodiment, one type of mother piezoelectric substrate is prepared, and in the same manner as in the above embodiment, electrode formation, frequency measurement, and cutting are performed. -A resonator manufacturing process may be performed.
[0030]
【The invention's effect】
According to the method for manufacturing a piezoelectric resonator according to the first aspect of the present invention, after the electrodes are formed on the mother piezoelectric substrate, the cut dimensions for obtaining the individual piezoelectric resonators are measured at the stage of the mother piezoelectric substrate. The mother piezoelectric substrate is cut according to the frequency or anti-resonance frequency measurement value and the magnitude of the deviation between the target frequency values. Therefore, frequency variations in individual piezoelectric resonators obtained by cutting can be remarkably reduced.
[0031]
Similarly, in the ladder filter manufacturing method according to the second invention, the resonance frequency or anti-resonance frequency is measured at the piezoelectric substrate stage of the first and second mothers, and the resonance frequency or anti-resonance frequency is measured. The first and second piezoelectric resonators are obtained by changing the cutting dimensions according to the deviation between the value and the target value. Therefore, the ladder type filter can be easily manufactured by combining the first and second piezoelectric resonators having a small frequency variation between the first and second piezoelectric resonators, and thus having a small frequency variation, as a series resonator and a parallel resonator. be able to.
[0032]
As described above, in the conventional method for manufacturing a piezoelectric resonator, the mother piezoelectric substrate is always cut so as to obtain a piezoelectric resonator having the same dimensions. Therefore, a complicated characteristic selection process must be performed. However, a complicated frequency adjustment process must be performed, and the piezoelectric resonator that cannot be adjusted has to be discarded. According to the first and second inventions of the present application, In addition to simplifying the complicated characteristic selection process, the frequency variation of the obtained piezoelectric resonator is reduced, so the frequency adjustment process can be simplified or omitted, and the yield rate of piezoelectric resonators can be greatly increased. Can be increased.
[Brief description of the drawings]
FIG. 1 is a process chart of a method for producing a ladder filter according to an embodiment of the present invention.
FIG. 2 is a circuit diagram of a ladder type filter obtained in an embodiment of the present invention.
FIG. 3 is a perspective view showing a first piezoelectric resonator obtained in an embodiment of the present invention.
FIG. 4 is a perspective view of a first mother piezoelectric substrate.
FIG. 5 is a schematic block diagram of an apparatus for frequency measurement and cutting a mother piezoelectric substrate in an embodiment of the present invention.
6A and 6B are schematic configuration diagrams for explaining a step of measuring a frequency of a mother piezoelectric substrate and a step of cutting the mother piezoelectric substrate in an embodiment of the present invention.
FIG. 7 is a process diagram for explaining an example of a conventional method of manufacturing a piezoelectric resonator.
[Explanation of symbols]
3 ... first mother piezoelectric substrate 4 ... vibrating electrode 6 ... piezoelectric resonator 7 ... piezoelectric substrate 11 ... control device 12 ... frequency measuring device 13 ... cutting devices P1-P3 ... parallel resonators S1-S2 ... series resonators

Claims (2)

A method of manufacturing a piezoelectric resonator using a spreading mode in which vibration electrodes are formed on both sides of a piezoelectric substrate,
Preparing a mother piezoelectric substrate;
Forming electrodes on both main surfaces of the mother piezoelectric substrate;
Measuring the resonance frequency or anti-resonance frequency of the mother piezoelectric substrate on which the electrodes are formed;
Depending on the magnitude of the positive or negative deviation with respect to the target frequency value of the resonance frequency or anti-resonance frequency, the cut size for obtaining each piezoelectric resonator is increased or decreased so that the mother piezoelectric Obtaining individual piezoelectric resonators by cutting the substrate;
Measuring a resonance frequency or an anti-resonance frequency of each piezoelectric resonator manufactured from a plurality of mother piezoelectric substrates, and selecting a characteristic. Preparing a plurality of first mother piezoelectric substrates and a plurality of second mother piezoelectric substrates;
Forming electrodes on both surfaces of the piezoelectric substrates of the first and second mothers;
Measuring the resonance frequency of the plurality of first mother piezoelectric substrates on which the electrodes are formed and the anti-resonance frequency of the plurality of second mother piezoelectric substrates on which the electrodes are formed;
The cutting dimensions of the plurality of first and second mother piezoelectric substrates are changed according to the frequency difference between the measured resonance frequency or anti-resonance frequency and the target resonance frequency or anti-resonance frequency, respectively. Cutting to obtain first and second piezoelectric resonators, respectively,
Measuring the resonance frequency of the first piezoelectric resonator and the anti-resonance frequency of the second piezoelectric resonator, and selecting the characteristics of the first and second piezoelectric resonators;
And a step of manufacturing a ladder filter by combining the selected first and second piezoelectric resonators as a series resonator and a parallel resonator, respectively.

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