JPS58188915A - Piezoelectric oscillator - Google Patents

Abstract

PURPOSE:To increase a Q group and to reduce spuriousness by constituting electrode patterns on the opposed main surfaces, and adhering conductor layers which connect the electrode patterns to outside of a piezoelectric body to the end part of the piezoelectric body opposed to one end part. CONSTITUTION:A couple of T-shaped electrode patterns 12 and 12' are vapor- deposited on the opposite main surfaces of the piezoelectric body 11 which is made of a rectangularly sectioned bar of lithium tantalate and has a length L in the longitudinal direction and a thickness T. Two couples of conductor layers 13 and 13', and 14 and 14' which have thickness (t) and width (w) are printed at lengthwise main surface end parts of the piezoelectric body 11. Further, the conductor layers 15 and 16 for connecting the conductor layers 13 and 13', and 14 and 14' are adhered to the piezoelectric body end parts to complete an oscillator 1. The thickness t/T of the conductor layers 13 and 13', and 14 and 14' is lilmited to 0.27-0.43 and the width (w) is limited to <0.06 to improve the performance.

Description

Detailed Description of the Invention (a) Technical Field of the Invention The present invention aims to connect an electrode pattern formed on a piezoelectric body to the outside by reducing the spurious and Q Concerning structures that improve value.

(b) Technical background Traditionally, quartz and lithium tantalate (t,iTsOs)
Piezoelectric vibrators using piezoelectric materials such as ) are small and have high performance, and are widely used as oscillation circuits or filters in communication devices and the like.

(C) Prior Art and Problems FIG. 1 is a side view showing the conventional structure of an IJ tap thickness peri-vibrator that supports a vibrating element made of a single crystal of LiTaO2.

In FIG. 1, a vibrating element 1 has a rectangular cross-section 0 rod-shaped piezoelectric body 2, and on its opposite main surface, an electrically connected pattern is formed by vapor deposition on the high part, and a T-shaped electrode pattern 3 extends in symmetrical directions from the center of the front and back surfaces shown in the figure. and 3' are formed. One end of a pair of support conductors 5 is fixed to the vicinity of the extended ends of the electrode patterns 3 and 3' via a conductive adhesive 4, and the other end of each conductor II 5 penetrates through the package base 6t. After fixing to the upper ends of the pair of lead terminals 7, the opening edge of the cap 8 is brought into close contact with the periphery of the base 60, thereby completing the illustrated vibrator.

However, in the vibrator having such a conventional configuration, spurious waves and variations in Q value (equivalent series resistance value Rs) are factors that reduce manufacturing yield, and countermeasures are not desired.

(d) Object of the Invention The object of the present invention is to eliminate the above-mentioned drawbacks, and this was accomplished by focusing on the adhesive (conductor layer) that adheres to the end of the vibrating element.

(e) Structure of the invention and the above object are achieved by a conductor layer connecting the counter electrode pattern to the outside of the piezoelectric body, which is attached to each of the ends of the piezoelectric body facing one side, and the main surface of the piezoelectric body of the conductor layer. Ru.

(f) Embodiments of the invention The present invention will be described below using drawings relating to embodiments of the invention.

FIG. 2 is a perspective view for explaining a vibrating element which is a -ψ embodiment of the present invention, and FIG. 3 is an actual measurement result supporting one aspect of the present invention. (yl ratio t/
T) Diagram showing Q value and series resonant resistance R1 versus K, 4th
The figure is a diagram showing the Q value with respect to the width W (width ratio W/L) of the conductor layer shown in Figure 2 as an actual measurement result supporting the other aspect of the present invention, and Figure 5 is a diagram showing the conductor layer thickness ratio t of the vibrating element. /T0.1
FIG. 6 is a diagram showing the frequency characteristics of the vibrator when the conductor layer thickness ratio t/'l' of the vibrating element is 0.36.

In FIG. 2A, a piezoelectric body 11 made of LiTa0a and having a rod shape with a rectangular cross section and a longitudinal length L and a thickness T.
A pair of T-shaped electrode patterns 12 and 12' similar to those of the vibrating element 1 shown in FIG.

Next, as shown in the opening of FIG. 2, two pairs of conductor layers 13 and 13' and 14 and 14', each having a thickness of t and a width of W, are formed on the end of the main surface in the longitudinal direction of the piezoelectric body 11 by printing means. It is deposited and formed. However, the conductor layer] 3 is stacked on the end of the electrode pattern 12, and the conductor layer 14'J't- is stacked on the end of the electrode pattern 12.
2' end.

Furthermore, as shown in FIG. 2C, the conductor layers 13 and 13'
Further, conductor layers 15 and 16 connecting 14 and 14', respectively, are attached to the ends of the piezoelectric body to complete the vibrating element 17.

In addition, the thickness, weight, and width Wri of the conductive layers 13 and 13' and 14 and 14' printed and composed of conductive paste (for example, silver paste) are determined based on the experimental results described later^, and the beating ratio t.
/T is approximately 027 to 043, and the width ratio W/L is 0.06 or less. In addition, the vibrating element 17F'i is mounted on a substrate, etc. of a vibrator package (not shown), and a pair of electrodes formed on the substrate, etc., or a support conductor (indicated by 5 in FIG. 1) with one end fixed, is a conductor layer. They are connected to the electrode patterns 12 and 12' through the electrode patterns 15 and 16, respectively, and this connection can be made at the same time as forming the conductor layers 15 and 16 by applying and baking a conductive paste. Then, a cap equivalent to the cap 8 of FIG. 1 is mounted on the substrate, etc., and the paulownia rotor is completed.

In Figure 3, the horizontal axis represents the thickness ratio t/T of the conductor layer.

The vertical axis on the left shows the Q value, which is the mechanical quality factor of the vibrator.
The Vi series resonant resistance Rs is taken on the right vertical axis, and
Curve A based on the results of actual measurement 1 shows the relationship between t/T and Q, and curve @B shows the relationship between t/T and Rs. However, the piezoelectric material used was FiLITso31iC.

The main surface length is 811. The main surface width is 17 stitches, the thickness T is 0.55 fl, and the conductor width ratio W/L is 0.05.

In Figure 3, the Q characteristic A has a thickness ratio t/'l' of 018
In this case, the Q value shows the lowest value of about 3750, which is 2, and the Q value of 5000 layer Fit/T is 0.11 or less and in the range of about 0.27 to 046. On the other hand, Rs.
Due to the characteristics, when t/'l'' is 0.18, @R-N value is 45Ω
t/TFi is in the range of about 0.29 to 0.42, showing the highest value of 30 Ω or less, which is the R3 # 4]1 value. Therefore, when t/T is about 0829 to 042, a vibrator is obtained in which both the Q value and the Rs value satisfy the Meyanagi value.

Figure 4 shows the ratio W/ of the piezoelectric length L of the piezoelectric body and the conductor layer width W.
The relationship between W/L and Q is shown by a curve C based on actual measurement results, with L on the horizontal axis and KQ value on the vertical axis.

In Figure 4, the Q characteristic channel conductor width ratio W/L is approximately 006
In the following cases, the Q value is almost constant, and at 6000 1)
When W/L becomes larger than 0.06, it rapidly decreases. Therefore, it is better to set W/L to 0806 or less.
The value will be guaranteed.

In FIG. 5, a vibrator was created using a vibrator with a conductor layer thickness ratio t/T of 01, and its frequency characteristics are shown as a curve [D], and the horizontal axis represents the frequency 'P1. (MHz) and the response level (dB) is plotted on the vertical axis.

Also, harmful Suirius 26 is recorded in the frequency characteristics.

On the other hand, Fig. 6 shows the frequency of the vibrator when the conductor layer thickness ratio t/'l' is 036 [Characteristics are shown in white group! In FIG. 6, where the horizontal and vertical axes are the same as those in FIG. (g) Effect of the Invention As explained above, the piezoelectric vibrator of the present invention has a Q It has excellent value and less spurious, and the effect of ensuring high quality and stable sexual ridges is the best.

[Brief explanation of drawings]

Fig. 1 is a partially cutaway side view of a strip type piezoelectric vibrator having a conventional configuration, Fig. 2 is an oblique P view for explaining an embodiment of the present invention, and Fig. 3 is the same as Fig. 2. A diagram showing the Q value and series resonant resistance Rs with respect to the thickness t of the conductor layer. FIG. 4 is a diagram showing the Q value with respect to the width W of the conductor layer 1, FIG. FIG. 6 is a diagram showing frequency timing of a vibrator with a ratio to of 36 between the length of the piezoelectric body and the width W of the conductor layer. In addition, in the figure, 1.17 is a pressure wry element, 2°11 is a piezoelectric body, and 3. 3', 12. 12' is an electrode pattern, 13, 1π, 14.14' is a conductor layer at the end of the piezoelectric body,
L is the length of the piezoelectric body, T is the thickness of the piezoelectric body, the thickness of the tVi end conductor layer, and the width of the WFi end conductor layer. Figure 1 Figure 3 Figure 0 θθqO, 1θ θ27 θ'; 6 0.
lL5 θ9f/T

Claims (2)

[Claims] (1) In a stop-type vibrator that utilizes the thickness-shear vibration mode of a piezoelectric material in which electrode patterns are formed on each of the opposing principal surfaces, a conductor layer that connects each electrode pattern to the outside of the piezoelectric material is a piezoelectric material that faces one side. A piezoelectric vibrator is attached to each end of the body and is pressed by the conductor layer. (2) A patented piezoelectric vibrator characterized in that the width of the conductor layer covering the main surface of the piezoelectric body is 6 inches or less of the length of the piezoelectric body in the direction in which the conductor layer faces.