JP4229669B2 - Method for measuring temperature characteristics of piezoelectric element plate - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a measurement method for measuring a frequency characteristic with respect to an ambient temperature change of an oscillation frequency in the form of a piezoelectric element plate.
[0002]
[Prior art]
As a typical piezoelectric element plate, a crystal material is used as an oscillation element in which electrodes are formed on the main surface of a crystal plate, such as a crystal resonator or crystal resonator, as a crystal piece cut from a natural or artificial crystal. Rather, it refers to a so-called piezoelectric element plate (called a blank in the industry).
[0003]
It is a general processing and manufacturing process to perform various characteristics evaluation as a crystal resonator or crystal resonator as an oscillation element after forming electrodes on the main surface of this piezoelectric (quartz) base plate and hermetically sealing This is the flow.
[0004]
By evaluating various characteristics in the form of a crystal resonator in this way, it is possible to obtain an extremely accurate and highly stable crystal resonator, and combining this crystal resonator with a semiconductor element (IC or transistor) The oscillator can be configured with. Crystal resonators and crystal oscillators are widely used as broadband parts and IT (information technology) related parts such as measuring instruments and transmitters.
[0005]
In addition, the temperature characteristics of quartz materials generally have a correlation with the cutting angle of the main surface of the quartz base plate, and the quartz crystal plate is controlled during processing to keep the frequency temperature characteristics of the quartz crystal and crystal oscillator within a certain range. A technique is adopted in which the cutting angle is measured by an X-ray diffraction method and is suppressed within a certain angular deviation.
[0006]
The applicant has not found any prior art documents related to the present invention by the time of filing of the present application other than the prior art documents specified by the prior art document information described in the present specification.
[0007]
[Patent Document 1]
Japanese Patent Laid-Open No. 06-140860 [Patent Document 2]
Japanese Patent Laid-Open No. 09-214270
[Problems to be solved by the invention]
As described above, the temperature characteristics of the crystal unit are measured in the form of a crystal unit with an electrode and a holding unit added to a piezoelectric (quartz) base plate, and the influence of the holding unit is thus affected. However, it is difficult to accurately measure the change in frequency characteristics due to the holding state (the stress applied to the piezoelectric element plate changes due to holding).
[0009]
For this reason, it is said that quality evaluation at the initial stage of processing a crystal unit is very important for evaluation of non-defective products of crystal units. The temperature characteristic in the state of the piezoelectric element plate is regarded as important.
[0010]
Here, it is necessary to measure the cutting angle of the quartz base plate by the X-ray diffraction method by holding the quartz base plate by a method such as vacuum suction in order to increase the accuracy. However, when the quartz base plate is very thin, the base plate is deformed by vacuum suction or the like, so that there is a problem that measurement cannot be performed with high accuracy. At the same time, there is a problem that even when the quartz base plate becomes very small, it is difficult to hold and the measurement cannot be performed with high accuracy.
[0011]
In addition, the X-ray diffraction method only measures the cutting angle and does not measure the necessary temperature characteristics, so when the oscillation is actually oscillated even if the cutting angle is within a certain range. There was also a problem that desired temperature characteristics could not be obtained due to the influence of parasitic vibration or the like.
[0012]
Therefore, the present invention is a frequency measurement in which a piezoelectric element plate is sandwiched between electrode plates and the frequency of the piezoelectric element plate is measured, and the temperature is obtained by providing heating and cooling means on the electrode plate as it is. This is a method for measuring the temperature characteristics of a piezoelectric element plate, wherein the temperature characteristics are confirmed while measuring the frequency. In short, this is a method of measuring the temperature characteristics of the piezoelectric element plate before forming an electrode plate on the main surface of the piezoelectric element like the above-described oscillation element and processing it into the form of a crystal resonator or a crystal resonator.
[0013]
In order to achieve temperature characteristics, it is necessary to forcibly change the temperature with the piezoelectric element plate sandwiched between the electrode plates. In the present invention, in order to realize this temperature change, heating provided to the electrode plate is required. And a Peltier element as a cooling means.
[0014]
Therefore, the present invention solves the problem by realizing confirmation of temperature characteristics at the time of the piezoelectric (quartz) element plate, which is the initial stage of processing the crystal resonator.
Furthermore, since there is no measurement in the form of a crystal resonator in which an electrode or a holding portion is added to a piezoelectric (quartz) base plate, the stress applied to the piezoelectric base plate due to the holding is changed. It is possible to measure the frequency characteristics accurately.
[0015]
Therefore, according to the present invention, the method of measuring the cutting angle of the quartz base plate by the X-ray diffraction method is improved, the deformation of the base plate due to vacuum suction or the like at the time of measurement, and the effect of holding when the quartz base plate becomes very small Thus, it is possible to improve the temperature characteristic measurement technique in the state of the piezoelectric element plate (crystal element plate).
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the accompanying drawings. In each figure, the same numerals indicate the same objects.
FIG. 1 is a view showing the concept of the temperature characteristic measuring method of the piezoelectric element plate 2 of the present invention.
As shown in FIG. 1, a frequency measurement system that sandwiches a piezoelectric element plate 2 between electrode plates and measures the frequency of the sandwiched piezoelectric element plate 2 and measures the frequency while checking the temperature characteristics of the piezoelectric element plate 2 itself. The measurement system for performing is shown.
[0017]
As an example, the piezoelectric element plate 2 is a crystal material of an AT cut plate, and the sandwiched electrode 1 is a metal such as a copper material. As shown in FIG. 2, the piezoelectric element plate 2 sandwiched between the metal to be the electrodes 1 has the piezoelectric element plate 2 mounted on the lower electrode as shown in FIG. The upper electrode is arranged.
[0018]
Each electrode 1 is connected to a network analyzer, and the characteristics of the piezoelectric element plate 2 itself can be measured. The temperature characteristics of the piezoelectric element 2 itself can be measured by exciting the piezoelectric element 2 with these measurement systems and simultaneously applying a temperature change to the piezoelectric element 2. Here, the frequency measurement is performed by a combination of a network analyzer and a computer as an example.
[0019]
Further, the present invention is characterized in that a Peltier element is used to apply a temperature change to the sandwiched piezoelectric element plate 2. Peltier elements are p-type and n-type semiconductor heat transfer elements arranged in parallel and electrically connected in series to cause current to flow, causing heat absorption and heat dissipation on each surface due to the Peltier effect. It is a possible element. The operation of heat absorption and heat dissipation of this Peltier element is shown in a simple conceptual diagram in FIG.
[0020]
FIG. 3 is a conceptual diagram of the Peltier effect. As shown in the figure, p-type and n-type semiconductors are arranged in parallel, electrically connected in series, and a low voltage (several volts to several tens of volts) is applied to both ends thereof, so that one side can be used. Consists of a semiconductor that transfers heat to the other side. In short, one side becomes cold and has an endothermic effect, and the other side becomes thicker and has a heat dissipation effect. A temperature change can be easily applied to the piezoelectric element plate 2 by arranging the Peltier element having the effect of heat absorption and heat dissipation in the electrode 1 part.
[0021]
By the temperature characteristic measurement system of the piezoelectric element plate 2 described above, confirmation of the temperature characteristic in the state of the piezoelectric (quartz) element plate, which is the initial stage of processing the crystal resonator, can be realized.
In the present embodiment, the piezoelectric element plate 2 is measured in an individual unit. However, a plurality of piezoelectric element plates 2 can be measured at a time by arranging a plurality of electrodes. Needless to say, the working efficiency of the measurement time can be improved.
In addition, the temperature of the electrode part is changed by the Peltier element, but the part where the piezoelectric element plate 2 is sandwiched between the electrode plates is supplementarily used in combination with an external temperature atmosphere environment such as a thermostatic bath. However, the same effect can be obtained.
[0022]
The feature of the present invention is that the temperature characteristic is measured in the state of the piezoelectric element plate, and as an example, the electrode plate is arranged so as to sandwich the piezoelectric element plate, but not particularly illustrated, The same effect can be obtained even with a measurement method in which a gap (gap) is provided between the piezoelectric element plate and the electrode. In this embodiment, the Peltier elements are arranged on both the upper and lower electrodes, but the temperature control may be performed by arranging them on either one of the electrodes.
[0023]
【The invention's effect】
According to the present invention, since the temperature characteristic evaluation as a piezoelectric element plate can be confirmed, the temperature as an oscillation element before forming an oscillation element, a crystal resonator, a crystal resonator, or a crystal oscillator in which an electrode is formed on the piezoelectric element plate. By performing the characteristic evaluation reliably, the quality confirmation work in the manufacturing process can be reduced. In addition, by increasing the number of crystal units that can be obtained as non-defective products compared to the absolute amount of piezoelectric element plates used in manufacturing and processing processes, the overall quality of crystal units can be improved and stable crystal units. Can be supplied to the manufacturing process.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram of a measurement method of the present invention.
FIG. 2 is a cross-sectional view of an electrode portion showing an embodiment of the electrode structure of the present invention.
FIG. 3 is a conceptual diagram illustrating the Peltier effect.
[Explanation of symbols]
1 Electrode 2 Piezoelectric element plate

Claims (1)

A frequency measurement in which a piezoelectric element plate is sandwiched between electrode plates and the frequency of the piezoelectric element plate is measured, and the temperature is changed by providing heating and cooling means on the electrode plate as it is, A method for measuring temperature characteristics of a piezoelectric element plate, wherein the temperature characteristics are confirmed while measuring the temperature.

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