JPH10190399A - Capacitor incorporating type piezoelectric oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-sized piezoelectric oscillator made equivalent to a chip-like component by achieving the ternary overtone oscillation of stable thickness vertical vibration and extremely miniaturizing the shape of a piezoelectric substrate. SOLUTION: Electrodes 12 and 13 extended to the different end parts of the piezoelectric substrate 11 mutually facing the thickness direction of the substrate 11 are formed on both main surfaces of the strip-like piezoelectric substrate 11 composed of a piezoelectric magnetic composition composed of a composite perovskite compound including Pb, La, Sr, Sb, Mn and Ti and at least one kind of Co, Yb and In as metal components and an energy confining type piezoelectric oscillation element for the ternary overtone of the thickness vertical vibration is attained. Further, two individual capacitor electrodes 22 and 23 and one common capacitor electrode 24 are formed on a dielectric substrate 21 and a strip-like capacitive element is attained. In this case, the piezoelectric oscillation element and the capacitive element are overlapped and arranged so as to electrically connect the electrodes of the piezoelectric oscillation element to the individual electrode 22 of the capacitive element and this oscillator is constituted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chip-shaped piezoelectric oscillator with a built-in capacitor utilizing a third overtone of thickness longitudinal vibration.

[0002]

2. Description of the Related Art A built-in capacitance type piezoelectric oscillator comprises a piezoelectric oscillation element and a capacitance element having two capacitance components, and forms a part of a Colpitts oscillation circuit.

[0003] Piezoelectric oscillators with built-in capacitors are widely used as oscillation components for reference signals of microcomputers mounted on electronic equipment, communication equipment and the like. With the increase in the frequency of the reference signal, a component that stably oscillates at a high frequency is desired.

Generally, in order to oscillate in a Colpitts oscillation circuit, an amplification factor α of an amplifier circuit including an inverter and a feedback resistor, a phase shift rate θ ₁ , and a feedback ratio of a feedback circuit including an oscillator and a load capacitance component are used. It is necessary to appropriately control β and the phase shift rate θ ₂ . That is, the loop gain is α × β ≧
1, and the phase shift amount needs to be θ ₁ + θ ₂ = 360 ° × n (where n = 1, 2,...).

In an oscillator such as a crystal oscillator,
As a method of high-frequency oscillation, it is known to use a third-order overtone oscillation from a fundamental wave operation. However, a piezoelectric oscillator with a built-in capacitor can be operated by a third-overtone oscillation from the fundamental wave operation. A solution is achieved.

In order to oscillate with this third overtone, a peak valley value (P / V value:
The difference between the impedance at the resonance frequency and the impedance at the anti-resonance frequency) must be greater than the P / V value of the fundamental wave. For this reason, it is important to suppress the fundamental wave and eliminate the occurrence of spurious near the third-order overtone.

[0007]

Conventionally, PbTiO ₃ or Pb (TiZr) has been used as a piezoelectric substrate material for a piezoelectric oscillator.
Those containing O ₃ as a main component, or Pb (Mn _1/3 Nb _2/3 ) O ₃ and Pb (Ni _1/3 Nb _2/3 ) O ₃ as the second and third components. And the like are known. In particular, in the case of a porcelain composition containing PbTiO ₃ as a main component, the electromechanical coupling coefficient of the thickness longitudinal vibration is larger than that of the spread vibration. Is small, and the dielectric constant is as small as 400 to 700.
It has a feature that it can be used in a high frequency region of MHz or more.

However, when a piezoelectric substrate is made of such a material, it is difficult to reduce the size of the substrate. For example, the ground area shape, which is a JIS standard value applied to chip capacitors and chip resistors, is 3.2 × 2.5 mm. (3225) Or
There was a problem that the size could not be reduced to 3.2 × 1.6 mm (3216). This is because when the fundamental wave is suppressed while maintaining the P / V value of the third overtone, it is necessary to increase the area of the non-electrode portion to be suppressed with respect to the area of the electrode formation portion of the piezoelectric substrate. .

Further, when the area occupied by the piezoelectric oscillation element on the circuit board becomes large, there is a problem that high-density mounting becomes difficult and the mounting speed on the circuit board becomes slow.

Further, conventional PbTiO is used for the piezoelectric oscillation element.
_When miniaturization is attempted by using a piezoelectric ceramic composition containing ₃ as a main component, an important factor for starting oscillation, that is, the P / V value of a third-order overtone that determines the feedback ratio β becomes small, and amplification occurs. There is a problem such as non-oscillation which does not operate in a microcomputer having a built-in amplifier having a relatively small rate α.

After all, conventional PbTiO ₃ and Pb (Ti
Zr) In order to stably perform the third overtone oscillation of the piezoelectric oscillation element formed using the piezoelectric substrate containing O ₃ as a main component, it is inevitable that the size of the piezoelectric substrate is increased. As a result, the shape of the capacitive element that generates the load capacitive component becomes unbalanced, which has seriously hindered the assembly of the piezoelectric oscillation element and the capacitive element and the sealing structure.

The present invention has been devised in view of the above-mentioned problems, and has as its object to specify a material of a piezoelectric substrate of a piezoelectric oscillation element so that the fundamental wave can be obtained without physically suppressing the fundamental wave. And the P / V value of the tertiary overtone increases, achieving stable tertiary overtone oscillation of thickness longitudinal vibration and extremely miniaturizing the shape of the piezoelectric substrate. It is intended to provide a built-in capacity type piezoelectric oscillator which is equivalent to a component.

Another object of the present invention is to provide a piezoelectric oscillator with a built-in capacitor which can sufficiently exhibit the above-mentioned object of miniaturization and which has a simplified structure for sealing a piezoelectric vibrating element and a capacitive element. .

[0014]

The present invention relates to a composite perovskite compound containing Pb, La, Sr, Sb, Mn, Ti as a metal component and at least one of Co, Yb and In. the molar ratio of the metal _{elements, (Pb 1-xy) z} La x Sr y (Co 1/3 Sb
_2/3 ) _a (Yb _1/2 Sb _1/2 ) _b (In _1/2 Sb _1/2 ) _c
When expressed as Mn _d Ti _{1-abc- d} O ₃ , X, Y, Z,
The molar ratio of a, b, c, d is 0.07 ≦ X ≦ 0.130.01 ≦ Y ≦ 0.07 0.94 ≦ Z ≦ 1.000 ≦ a ≦ 0.030 ≦ b ≦ 0.030 ≤ c ≤ 0.03 0.01 ≤ a + b + c ≤ 0.04 0.01 ≤ d ≤ 0.03 Both main surfaces of a rectangular piezoelectric substrate made of a piezoelectric ceramic composition satisfying the following conditions: An energy trapping type piezoelectric oscillator for tertiary overtone of thickness longitudinal vibration in which electrodes extending in different directions of the substrate are opposed to each other in the thickness direction, and two individual capacitance electrodes and one common capacitance are provided on the dielectric substrate. The electrode of the piezoelectric oscillation element electrically connects a capacitor element that forms an electrode, and a capacitor element that generates two capacitance components between the individual capacitor electrode and the common capacitor electrode to the individual electrode of the capacitor element. Oscillator with Built-in Capacitor A.

[0015] Further, as a bonding and sealing structure of the piezoelectric oscillating element and the capacitive element, the piezoelectric oscillating element and the capacitive element are joined at both ends in the longitudinal direction via a conductive adhesive material. This is a built-in capacitance type piezoelectric oscillator covered with a cover having a substantially concave shape that sandwiches the long side surface of both elements from the side.

[0016]

According to the present invention, a high P / V value can be obtained with a third overtone even when the size of the piezoelectric oscillation element is reduced from the material of the piezoelectric substrate constituting the piezoelectric oscillation element. First, as the piezoelectric ceramic composition, Pb and L are used as metal components.
a, Sr, Sb, Mn, Ti, Co, Yb and In
At least one a composite perovskite compound including a composition formula by molar ratio of the metal _{elements, (Pb 1-xy) z} La x Sr y (Co 1/3 Sb of
_2/3 ) _a (Yb _1/2 Sb _1/2 ) _b (In _1/2 Sb _1/2 ) _c
When expressed as Mn _d Ti _1-abcd O ₃ , X, Y, Z,
the molar ratio of a, b, c, d is 0.07 ≦ X ≦ 0.13,
0.01 ≦ Y ≦ 0.07, 0.94 ≦ Z ≦ 1, 0 ≦ a ≦
0.03, 0 ≦ b ≦ 0.03, 0 ≦ c ≦ 0.03, 0.
01 ≦ a + b + c ≦ 0.04, 0.01 ≦ d ≦ 0.03
And

Here, the reason why X, Y, Z, a, b, c, and d are set in the above ranges will be described. La of Pb
The proper amount replacement by the above contributes particularly to facilitate the polarization and to improve the P / V value in the third overtone. 0.07 ≦ X ≦
The reason for setting the value in the range of 0.13 is that when the value is smaller than 0.07, it is difficult to cause polarization, and the P / V value decreases. If it is larger than 0.14, spurious generation is likely to occur, and the Curie temperature is greatly reduced, so that the reflow heat resistance is significantly deteriorated.

The proper replacement of Pb with Sr has the effect of significantly affecting the temperature characteristics of the oscillation frequency.
The reason for setting the range of 01 ≦ Y ≦ 0.07 is 0.01
If the temperature is less than the above, the temperature change of the oscillation frequency exceeds the range of ± 0.2% in the temperature range of −20 ° C. to + 80 ° C. If it exceeds 0.07, the Curie temperature decreases and the reflow heat resistance cannot be satisfied.

When the stoichiometric composition value of Pb is made smaller than the stoichiometric composition value, the P / V value can be greatly improved. The reason for setting the range of 0.94 ≦ Z ≦ 1.00 is that
The P / V value can be improved as the value is less than 1, but
If it is less than 0.94, the reflow heat resistance is remarkably deteriorated, and the rate of change of the oscillation frequency fosc exceeds ± 0.2%. When it was larger than 1, a decrease in the P / V value was observed. Therefore, the range of Z is a range in which the reflow heat resistance is sufficiently maintained while improving the P / V value.

(Co _1/3 Sb _2/3 ) or (Y
b _1/2 Sb _1/2) or (at least one or more substitutions of In _1/2 Sb _1/2) is the third overtone P / V
This has the effect of reducing the P / V value of the fundamental wave while increasing the value. 0.01 ≦ a ≦ 0.0
3, 0.01 ≦ b ≦ 0.03, 0.01 ≦ c ≦ 0.0
3. The reason for setting the range of 0.01 ≦ a + b + c ≦ 0.04 is that when a, b, c and a + b + c are set, 0.0
If the number is less than 1, the P / V value of the fundamental wave increases, and erroneous oscillation is likely to occur. Further, in the case of single substitution of a, b and c, if it is more than 0.03, the P / V value becomes small and the reflow heat resistance is deteriorated. Also, a
When the compound substitution is performed so as to be + b + c, the upper limit of the substitution amount is extended to 0.04, and the substitution beyond that deteriorates the heat resistance.

The proper replacement of Ti by Mn greatly contributes to the improvement of the P / V value. The reason for setting the range of 0.01 ≦ d ≦ 0.03 is that if it is less than 0.01, it does not contribute much to the improvement of the P / V value. If it exceeds 0.03, P / V
This is because the value is reduced on the contrary.

The shape of the piezoelectric substrate produced from the above-described piezoelectric ceramic composition is such that the long side is 3.2 mm or less and the short side is 1.0 to 1.0 mm.
By setting the electrodes to be 1.4 mm and opposing each other on both main surfaces, a piezoelectric oscillation element capable of stable tertiary overtone oscillation is possible. The opposing areas of the vibrating electrodes formed on both main surfaces of the piezoelectric substrate are 0.5 to 0.8 mm in the longitudinal direction of the substrate, and 0.6 to 0.8 mm in the substrate width direction.
1.0 mm, having the same width and extending to both short sides of the substrate.

A capacitive element is electrically connected to such a piezoelectric oscillation element. Since the capacitive element is formed using a dielectric substrate having substantially the same planar shape as the piezoelectric substrate, even if the piezoelectric oscillator and the capacitive element are arranged on top of each other, any one of the substrates can be used. Does not protrude greatly in the plane direction, so that a chip-shaped piezoelectric oscillator can be easily formed.

In the capacitive element, each capacitive electrode is formed so as to form a capacitive component between both electrodes of the piezoelectric oscillation element and the ground potential. That is, two capacitance components need to be achieved in the dielectric substrate, and two individual capacitance electrodes and one common capacitance electrode are formed. On the main surface side facing the piezoelectric oscillation element, two individual capacitance electrodes are formed at both ends. Thus, by interposing a conductive adhesive between the piezoelectric oscillation element and the capacitance element, that is, in the vicinity of both ends thereof, both can be mechanically joined to each other, and one of the main surfaces of the piezoelectric substrate can be joined. The formed electrode and the individual capacitance electrode formed on the other main surface of the dielectric substrate can be electrically connected.

In the second invention, the piezoelectric oscillator thus obtained is fixed on the capacitor at both ends thereof, and the fixed oscillator and the capacitor are connected to the upper surface of the piezoelectric substrate, the piezoelectric substrate and the piezoelectric substrate. By sandwiching the capacitive element between the concave cover portions that cover both end surfaces on the long side, a very small chip-shaped piezoelectric oscillator can be achieved. For example, the mounting area of the printed wiring board can be 3.2 × 2.5 mm or less, and the thickness is substantially the thickness of the upper surface of the cover, the thickness of the piezoelectric oscillation element, and the thickness of the capacitive element. The sum of the three thicknesses, the height is 1.5 mm or less, the P / V value of the fundamental wave is small, the P / V value of the third harmonic is large, and the built-in capacitor type piezoelectric that can oscillate at high frequencies. An oscillator can be obtained. In addition, since the piezoelectric oscillation element, the capacitance element, and the like are excellent in heat resistance, they are piezoelectric oscillators compatible with surface mounting.

[0026]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a piezoelectric oscillator with a built-in capacitor according to the present invention.

FIG. 1 is an external perspective view of a built-in capacitor type piezoelectric oscillator of the present invention, FIG. 2 is a perspective view of a state where only a cover portion is disassembled and removed, and FIG. 3 is a sectional structural view.

In the figure, reference numeral 1 denotes a piezoelectric oscillation element;
Is a capacitor, 3 is a cover, and 4 and 5 are terminal electrodes.

The piezoelectric oscillation element 1, by substituting a part of Pb of PbTiO ₃ in La and Sr, a portion of Ti and Mn, further _{(Co 1/3 Sb 2/3)} , (Yb 1/2 Sb _1/2 ), (I
n _1/2 Sb _1/2) to replace at least one of the, further the strip-shaped piezoelectric substrate 11 made of a piezoelectric ceramic composition was less than the stoichiometric composition amount Pb, which is formed on both major surfaces the electrodes 12 and 13. For example, the shape of the piezoelectric substrate 11 has a long side of 3.2 mm, a short side of 1.1 mm,
It has a thickness of 0.22 mm. Also, the electrodes 12, 13
Is an Ag-based material (Ag alone, Ag alloy monolayer, or A
g or a laminated film structure including a layer of an Ag alloy).

In FIG. 1 to FIG. 3, the electrode 12 is
The electrode 13 is formed to extend from the center of one main surface to one end, and the electrode 13 is formed to extend from the center of the other main surface of the piezoelectric substrate 11 to the other end. The facing area near the center of both electrodes is 0.5 in the longitudinal direction of the substrate 11.
0.8 mm, and 0.6 to 1.0 mm in the substrate width direction.

The capacitive element 2 is a strip-shaped dielectric substrate 21
And an individual capacitance electrode 2 for forming two capacitance components
2 and 23 and a common capacitance electrode 24. The dielectric substrate 21 is made of a dielectric material such as alumina, barium tatinate, or the like.
It is the same as the piezoelectric substrate 11 described above. The individual capacitance electrodes 22 and 23 and the common capacitance electrode 24 are made of an Ag-based material (Ag alone,
(A single-layer body of Ag alloy, or a single-layer body of Ag, or a laminated structure including a layer of Ag alloy).

In FIGS. 1 to 3, the individual capacitance electrodes 22, 23 are shown.
Are formed at both ends of one main surface of the dielectric substrate 21, and the common capacitance electrode 24 is formed at the center of the other main surface of the dielectric substrate 21. Thereby, the two individual capacitance electrodes 2
Capacitance components are respectively generated at opposing portions of the common capacitance electrodes 24 which oppose the dielectric substrates 2 and 23 in the thickness direction of the dielectric substrate 21.

The above-described piezoelectric oscillation element 1 and the capacitance element 2 having two capacitance components are provided at both ends such that the other main surface of the piezoelectric oscillation element 1 and one main surface of the capacitance element 2 face each other. They are integrated so as to overlap each other via the conductive adhesive 6. Specifically, the piezoelectric element 1 is joined to both ends of the other main surface of the piezoelectric oscillation element 1 via the conductive adhesive 6 in the formation region of the individual capacitance electrodes 22 and 23 on one main surface of the capacitance element 2. Therefore, for example, the electrode 13 formed on the other main surface of the piezoelectric oscillation element 1 is electrically connected to the individual capacitance electrode 23 of the capacitance element via the conductive adhesive 6.

The cover 3 has an elongated concave shape so as to cover the upper surface of the piezoelectric oscillation element 1 and both end faces on the long side of the capacitive element 2. The longitudinal dimension of the cover portion 3 is the same as the length of the piezoelectric substrate 11 or the dielectric substrate 21, and the shape of the cross-sectional concave portion is substantially the cross-sectional shape in which the piezoelectric substrate 11 and the dielectric substrate 21 are overlapped. ing.

The cover 3 having such a long concave shape is used.
A groove 31 forming a vibration space of the electrode 12 on one main surface of the piezoelectric substrate 21, for example, is formed on the inner surface of the piezoelectric substrate 21.

Such a gabber unit 3 includes the piezoelectric oscillation element 1
And a composite element in which the capacitor element 2 and the capacitor element 2 are bonded to each other via an epoxy adhesive 7. Specifically, as shown by hatched portions in FIG. 2, the piezoelectric substrate 1 is bonded to both ends of one main surface, both ends of a long side end surface, and a long side end surface of the capacitive element 2. Since the epoxy-based adhesive 7 is formed with a thickness of, for example, 5 to 20 μm, the groove 31 for securing the vibration space described above can be omitted.

An end of the composite element in which the piezoelectric oscillation element 1 and the capacitance element 2 are joined together with the cover 3 attached thereto, ie,
Terminal electrodes 4 and 5 are formed on the end faces of the piezoelectric substrate 11 and the dielectric substrate 21 by applying and curing a conductive paste containing an Ag material. The terminal electrode 4 formed on one end face is connected to the electrode 12 extending to the end face on one main face of the piezoelectric substrate 11 and the dielectric substrate 2
1 is connected to the individual capacitance electrode 22 extending to one end surface of one main surface. Further, the terminal electrode 5 formed on the other end surface extends to the electrode 13 extending from one main surface of the piezoelectric substrate 11 to the end surface and to the other end surface side of the one main surface of the dielectric substrate 21. It will be connected to the output individual capacitance electrode 23.

If necessary, a surface plating layer such as Ni plating, Sn plating, or solder plating may be formed on the surfaces of the terminal electrodes 4 and 5.

According to the above-described configuration, one electrode 12 of the piezoelectric oscillation element 1 has the individual capacitance electrode 22 and the common capacitance electrode 24.
And the capacitance component generated between them is connected. The other electrode 13 of the piezoelectric oscillation element 1 is connected to a capacitance component generated between the individual capacitance electrode 23 and the common capacitance electrode 24.

At the same time, one electrode 12 of the piezoelectric oscillation element 1
Is connected to the terminal electrode 4 to form, for example, an input-side terminal electrode, and the other electrode 13 is connected to the terminal electrode 5 to form, for example, an output-side terminal electrode. Further, the common capacitance electrode 24 formed on the capacitance element 2 becomes a terminal electrode of the ground potential.

According to the present invention, since the piezoelectric substrate 11 of the above-described piezoelectric oscillation element 1 is constituted by using a piezoelectric material of a predetermined composition, even if the planar shape is substantially the same as the capacitance element 2,
Third-order overtone oscillation can be stably performed.

As described above, the piezoelectric oscillation element 1 and the capacitance element 2
Since the planar shapes of the piezoelectric element 1 and the capacitive element 2 are superposed on each other,
And the overall thickness is
Of the piezoelectric substrate 11, the thickness of the dielectric substrate 21 of the capacitive element 2, and the thickness of the upper surface side of the cover 3 are substantially added. Therefore, this piezoelectric oscillator with a built-in capacitor becomes a chip-shaped component having a small size and a low profile together with the above-described high-frequency oscillation.

[0043]

Embodiments of the present invention will be described below. As raw materials, Pb ₃ O ₄ , La ₂ O ₃ , SrCO ₃ , Sb
₂ O ₃ , MnO ₂ , TiO ₂ , CO ₃ O ₄ , Yb
Various oxides composed of ₂ O ₃ and In ₂ O ₃ were used. Note that the raw material is not limited to this, and other compounds can be used as long as the compounds eventually become the above-mentioned oxides. These were weighed to the ratios shown in Table 1 and wet-mixed for 24 hours in a ball mill. Next, after dehydrating and drying this mixture, it was calcined at 1000 ° C. for 3 hours, an appropriate amount of an organic binder was added, dry-mixed, and passed through a mesh container and sized. The powder thus obtained was formed into a plate of 20 × 30 × 1.5 mm at a pressure of 1.5 to ³ ton / cm ³ ,
The sintering was performed in a temperature range of 0 to 1300 ° C. to obtain a piezoelectric ceramic.
Thereafter, the sheet thickness is processed to 0.22 mm, and Ag-C
r was deposited and polarized. Thereafter, an electrode at a portion corresponding to the non-electrode is removed by etching so as to obtain an electrode structure shown in FIG.
An oscillator for thickness third order overtoning corresponding to 3.86 MHz oscillation was obtained.

The characteristics of the oscillator were determined by measuring the impedance waveform with an impedance analyzer, and determining the P / V value at the third overtone of the thickness longitudinal vibration and the P / V value at the fundamental wave.
The value and relative permittivity ε ₃₃ ^T / ε ₀ were calculated by the following equations.
Furthermore, the temperature characteristics of the oscillation frequency were investigated using a Colpitts oscillation circuit. The heat resistance was measured by performing a reflow heat resistance test and a heat shock test, and was regarded as a change rate of the oscillation frequency Fosc.

In the reflow test, a test piece was exposed at a maximum temperature of 265 ° C. for 20 seconds using a reflow furnace. In addition, the heat shock was such that an operation of holding at −55 ° C. for 30 minutes and then holding at 85 ° C. for 30 minutes was defined as one cycle, and was repeated 100 cycles.

P / V value = 20 × Log (R _a / R _o ) where _Ra : anti-resonance impedance _Ro : resonance impedance ε ₃₃ ^T / ε ₀ = tC / εS where ε: dielectric constant in vacuum (8.854 × 10 ^-12 F /
m) S: Area of the vibrating part (m ² ) C: Free capacitance The temperature characteristic of the oscillation frequency was calculated by the following equation based on 25 ° C.

Fosc change rate (%) = ｛(Fosc _(drift)
−Fosc ₍₂₅₎ ) / F osc ₍₂₅₎ ｝ × 100 where Fosc _(drift) is the oscillation frequency at −20 ° C. or + 80 ° C.

Fosc ₍₂₅₎ : Oscillation frequency at 25 ° C. Each heat resistance test of reflow and heat shock was evaluated as follows.

Fosc change rate (%) = ｛(Focc after processing
-Fosc before treatment) / Fosc before treatment x 100 The results are shown in Table 1 (molar ratio of composition) and Table 2 (comparison of properties).

[0050]

[Table 1]

[0051]

[Table 2]

In the oscillator characteristics at 33.86 MHz, in order to guarantee stable oscillation, the fundamental wave of the P / V value is 40 dB or less, the third-order overton is 60 dB or more, and the temperature of the oscillation frequency is It is desired that the variation rate of the oscillation frequency be ± 0.2% or less due to the characteristics of ± 0.2% or less and the heat resistance of reflow heat and heat shock.
Further, the relative dielectric constant is desirably 400 or less.

In the table, those marked with * are outside the scope of the present invention,
Others are within the scope of the present invention.

As is clear from Tables 1 and 2, in this embodiment, the P / V value of the fundamental wave can be reduced while the P / V value at the third overtone is increased.
Oscillation stabilization and erroneous oscillation are suppressed, and excellent oscillation performance can be guaranteed. Further, it was found that the temperature change rate of the oscillation frequency was small and the oscillation frequency was excellent in temperature stability. Further, in heat resistance, the rate of change in both reflow heat resistance and heat shock heat resistance was extremely small, and it was found that heat resistance was excellent. In addition, the relative permittivity is smaller than 400, which indicates that the device is adapted to a high frequency.

On the other hand, in samples Nos. 4 and 15 which are comparative examples, the P / V value of the third overtone is small and non-oscillation occurs. In Sample Nos. 19 and 22, the P / V value of the fundamental wave is large with respect to the third overtone, and erroneous oscillation in the fundamental wave is likely to occur.

As described above, in the piezoelectric ceramic composition according to the above example, the P / V value of the fundamental wave could be reduced while the P / V value of the third overtone was increased. Erroneous oscillation does not occur, and furthermore, it has excellent heat resistance, and can be used as an oscillator in a wide temperature range of -20 to + 80 ° C.

According to the piezoelectric ceramic composition obtained here, 1.
Using a 1 × 3.2 mm × 0.22 mm thick piezoelectric oscillator, a small-sized piezoelectric oscillator with a built-in capacitor as shown in FIG. 3 was produced. The small-sized piezoelectric oscillator was bonded and fixed at both end portions via a conductive paste on an alumina substrate having the same load capacity as the piezoelectric oscillator. Next, a cover portion is formed from a liquid crystal polymer having a thickness of 0.2 mm so as to have a concave structure,
After the conductive adhesive is applied around the inner wall, the piezoelectric oscillator is sealed while being sandwiched between the alumina substrate and the cover. Ag paste for driving was applied to both end portions. In the vibrating part of the piezoelectric oscillation element, a vibrating gap is secured by the thickness of the adhesive layer, and the vibration response is not suppressed.
/ V value can be secured.

In the piezoelectric ceramic composition used in the present invention, Pb
Part of Pb of TiO ₃ is replaced by La and Sr, part of Ti is replaced by Mn, (Co _1/3 Sb _2/3 ), (Yb
By physically replacing the fundamental wave by substituting at least one of _1/2 Sb _1/2 ) and (In _1/2 Sb _1/2 ) and making the Pb content smaller than the stoichiometric composition. And the P / V of the fundamental wave becomes smaller, and the P
/ V value can be greatly increased,
It is possible to obtain a piezoelectric oscillation element that eliminates non-oscillation and eliminates a malfunction in which the oscillation frequency shifts to the fundamental frequency. Since the desired characteristics can be obtained only by holding the two ends of the piezoelectric oscillation element thus obtained, a rectangular shape of the piezoelectric oscillation element can be adopted, and the size of the piezoelectric oscillation element can be reduced. Will be. Furthermore, the ground area becomes 3.2 × 2.5 mm or less, and the cover portion is formed by sandwiching the piezoelectric oscillation element between a capacitance element as a constituent member and a concave resin or ceramic cover. Since the number of members in the thickness direction is reduced to three by forming a capacitor, a low-profile piezoelectric oscillator having a height of 1.5 mm or less and a built-in capacitor can be obtained.
Further, since the piezoelectric vibrator and the respective constituent members of the piezoelectric vibrator have excellent heat resistance, the piezoelectric vibrator is compatible with surface mounting.

In the above embodiment, the individual capacitance electrodes 22 and 23 and the common capacitance electrode 24 of the capacitance element 2 are formed on different main surfaces, respectively. The capacitance component may be formed between the planar electrodes by being circulated around the one main surface of the dielectric substrate, one end surface on the long side, the other main surface, and the other end surface on the long side in the order of the electrodes. .

[0060]

As described above, in the piezoelectric oscillator according to the present invention, the porcelain composition of the piezoelectric substrate of the piezoelectric oscillation element is represented by (Pb _1-xy ) _{z in the} composition formula based on the molar ratio of the metal element.
_{La x Sr y (Co 1/3 Sb} 2/3) a (Yb 1/2 Sb
_{1/2) b (In 1/2 Sb 1/2} ) c Mn d Ti 1-abcd O
_When represented as ₃ , the molar ratio of X, Y, Z, a, b, c, d is 0.07 ≦ X ≦ 0.13, 0.01 ≦ Y ≦ 0.07,
0.94 ≦ Z ≦ 1, 0 ≦ a ≦ 0.03, 0 ≦ b ≦ 0.0
3, 0 ≦ c ≦ 0.03, 0.01 ≦ a + b + c ≦ 0.0
4. By setting 0.01 ≦ d ≦ 0.03, the P / V value of the third overtone can be increased while the P / V value of the fundamental wave of the thickness longitudinal vibration is reduced, and the oscillation frequency is further increased. Has a small rate of change in temperature, is excellent in reflow heat resistance and heat resistance of heat shock, enables stable third-order overtone oscillation, and can be made extremely small and rectangular.

Therefore, by using this oscillation element and a capacitance element having two capacitance components in an overlapping manner,
A stable tertiary overtone oscillation is possible, and a built-in capacity type piezoelectric oscillator as a chip-shaped component is obtained.

Further, since the superposed piezoelectric oscillation element and the capacitance element having substantially the same planar shape are covered with the elongated concave cover portion, the sealing structure is simplified, and the size and the height are reduced. This is a piezoelectric oscillator with a built-in capacitor.

[Brief description of the drawings]

FIG. 1 is an external perspective view of a built-in capacitor type piezoelectric oscillator of the present invention.

FIG. 2 is a perspective view of the built-in capacity type piezoelectric oscillator of the present invention with a cover portion removed.

FIG. 3 is a cross-sectional view of a built-in capacitor type piezoelectric oscillator of the present invention.

[Explanation of symbols]

 1 ··· Piezoelectric oscillation element 2 ··· Capacitance element 3 ··· Cover part 4, 5 ··· Terminal electrode

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masanobu Choji 1-1, Yamashita-cho, Kokubu-shi, Kagoshima Inside the Kyocera Corporation Kagoshima Kokubu plant

Claims (2)

[Claims] (1) Pb, La, Sr, Sb,
Mn, Ti and, Co, Yb, a composite perovskite compound containing at least one of In, the molar ratio of the metal _{elements, (Pb 1-xy) z} La x Sr y (
_{Co 1/3 Sb 2/3) a} (Yb 1/2 Sb 1/2) b (In 1/2
Sb _1/2) when expressed as _{c Mn d Ti 1-abcd O} 3,
X, Y, Z, a, b, c, and d extend at different ends of the piezoelectric substrate to both main surfaces of a rectangular piezoelectric substrate made of a piezoelectric ceramic composition satisfying the following values: An energy trapping type piezoelectric oscillator for tertiary overtone of thickness longitudinal vibration having a pair of electrodes formed thereon, and two individual capacitance electrodes and one common capacitance electrode formed on a dielectric substrate. 2 between electrodes
Wherein a strip-shaped capacitive element having generated two capacitive components is disposed so as to overlap with each other so that an electrode of the piezoelectric oscillation element is electrically connected to an individual electrode of the capacitive element. Piezoelectric oscillator. 0.07 ≤ X ≤ 0.13 0.01 ≤ Y ≤ 0.07 0.94 ≤ Z ≤ 1.00 0 ≤ a ≤ 0.030 ≤ b ≤ 0.030 ≤ c ≤ 0.03 0.0. 01 ≦ a + b + c ≦ 0.04 0.01 ≦ d ≦ 0.03 2. The method according to claim 1, wherein the piezoelectric oscillation element and the capacitance element are joined at both ends in a longitudinal direction via a conductive adhesive.
2. The built-in capacity type piezoelectric oscillator according to claim 1, wherein a long concave-shaped cover sandwiching both long side surfaces of the two elements from the piezoelectric oscillation element side is covered.