JPH0422567Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Technical Field) The present invention relates to the shape of a tuning fork type piezoelectric element formed by a photo etching method.

(Prior Art and Problems) In the field of tuning fork vibrators using crystals, various ideas have been made to stably hold the element and improve the accuracy of the holding position and direction. An example of the most advanced conventional tuning fork type crystal piece will be explained with reference to the drawings. FIG. 3a is a front view showing a connection structure between a conventional tuning fork crystal piece and a crystal frame, and FIG. 3b is a diagram showing the conventional tuning fork crystal piece supported by a lead wire. be.

A tuning fork-shaped crystal piece 1 is created using photo-etching technology from a thin crystal plate polished to a specified thickness.
(hereinafter abbreviated as crystal piece 1) and crystal frame 2 (hereinafter abbreviated as crystal blank 1)
It is abbreviated as frame 2. ) is cut out leaving the connecting part 23. When this crystal piece 1 is assembled as a crystal resonator, the connecting portion 231 between the connecting portion 23 and the crystal piece 1 is folded from the frame 2 and separated into individual pieces for use. The shape of the connecting part is a trapezoid whose width gradually becomes narrower as it approaches the crystal piece from the frame body, and when separating the crystal piece 1 from the frame body 2, the crystal piece is the narrowest part and weakest against external force. The connection point 231 at the center of the base 11 in the crystal piece width direction W (hereinafter referred to as the W direction) is most likely to break. Furthermore, protrusions 114 that protrude in the longitudinal direction L of the crystal piece 1 (hereinafter referred to as the L direction) are formed at both ends of the crystal piece base 11 in the W direction, and the maximum dimension of the crystal piece in the L direction is Accuracy is guaranteed.

Nowadays, as the trend towards miniaturization continues to advance, the support structure of tuning fork crystal resonators has also changed, and the most suitable support structure for miniaturization and automation has become a support structure that connects the lead wire 4 and electrical machinery to only one main surface of the crystal blank 1. A structure that connects the Next, a method of configuring this support structure will be explained. When the individual crystal pieces 1 separated from the frame are inserted into an adhesive jig (not shown) in which the airtight terminal 3 is set in advance, the tips 41 of the two lead wires 4 protrude from the top surface of the airtight terminal 3.
The bottom portion 11 of one of the main surfaces of the crystal blank 1 is in contact with the bottom portion 11 of the crystal blank 1. When a load of several hundred grams is applied to this part, the crystal blank 1 and the lead wire 4 are brought into close contact with each other, and high frequency heating is applied, the plating (Sn, etc.) applied to the lead wire 4 melts and the crystal blank 1 is heated.
An extraction electrode (not shown) provided on the bottom 11 of the lead wire tip 41 is electrically and mechanically connected.

In the support structure described above, in order to maintain the accuracy of the connection position of the crystal piece 1 and the connection strength, the contact surfaces of the lead wire 4 and the crystal piece 1 must be pressed tightly together with several hundred grams. However, as the crystal piece 1 becomes ultra-small and ultra-thin, when the conventional crystal piece is connected to the lead wire 4 by the above method, as shown in FIG. Cracks and cracks 116 occur in the crystal element 11, and the symmetry in the W direction is lost in the shape of the crystal piece, which disrupts the balance of vibrational energy, increases leakage of vibrational energy to the outside, and increases variations in electrical characteristics. In addition, when a shock such as dropping is applied after the container is sealed, cracks occur from the micro cracks 115, and cracks of the crystal adhere to the vibrating part 12 of the crystal blank 1, causing oscillation to stop, frequency fluctuations, etc. This resulted in a significant decrease in yield. Also, the fourth
As shown in figure a, the base lower part of the tuning fork type piezoelectric element is
A structure in which the frame is connected to the frame body at a certain point is also disclosed (Japanese Patent Application Laid-Open No. 179013/1983), but as shown in FIG.
It had the same problems as the conventional example described above, such as chipping. In addition, in both figures of Figure 4, 24,
25 is a connecting part, 241, 251 is a connecting part, 11
7 is a crack, a crack. The inventor of the present invention believes that the cause of this is mechanical defects such as minute cracks 115 that occurred at the separated part of the W-direction center 13 of the base of the crystal piece when the crystal piece 1 was separated from the frame 2, and the narrow width of the protrusion 114. It has been found that this is due to the acute-angled shape of the base of the protrusion 114.

(Purpose of the invention) The present invention was made in view of the above circumstances, and is a mechanical method that can stably hold even ultra-compact, ultra-thin acoustic or single piezoelectric elements without causing cracks or cracks. The object of the present invention is to provide a tuning fork type piezoelectric element with extremely little distortion and acute-angled portions.

(Structure of the invention) The present invention provides a tuning fork type piezoelectric element that is formed integrally with a frame using photo etching, is obtained by being separated from the frame, and has lead terminals connected near both ends in the width direction. Each tuning fork type piezoelectric element has two connected pieces at both ends in the width direction of its base,
The bottom side of the tuning fork type piezoelectric element is formed at a position lower than the two connection points in the longitudinal direction of the tuning fork type piezoelectric element, and the bottom side of the tuning fork type piezoelectric element is located at a lower position in the longitudinal direction of the tuning fork type piezoelectric element. The width of the horizontal frame of the frame body gradually decreases as the distance from the connecting point increases.

(Example) A tuning fork type piezoelectric element according to the present invention will be explained by taking a tuning fork type crystal piece as an example.

(First Embodiment) A first embodiment of the present invention will be described with reference to the drawings. Fig. 1a is a front view showing the tuning fork-shaped crystal piece according to the present invention connected to the frame, Fig. 1b is an enlarged view of the connecting part with the frame, and Fig. 1c is the tuning fork-shaped crystal piece according to the present invention. FIG. 3 is a front view showing a state in which a crystal piece is mounted on an airtight terminal.

After polishing both main surfaces to a specified thickness (approximately 100 μm) and forming electrodes on the main surfaces of thin metal films using a sputtering method, etc., a thin crystal plate with a resist film patterned using a photolithography method is mounted on the quartz thin plate. Etching is performed using an etching solution such as ammonium chloride, and a large number of crystal pieces 1 are formed by die-cutting from a thin crystal plate. At this time, each crystal piece 1 has its base 11
It is connected to the frame 2 left during etching,
This connection point 211 is at both ends of the crystal piece 1 in the W direction,
In the L direction, it is located above the bottom side 111 of the crystal piece 1. The outer shape of the crystal piece 1 near the base 11 is the side 112 parallel to the W direction near the connection point 211.
And, in the L direction with respect to this side, 100 to 300 μm
It is formed by a stepped bottom side 111 and an oblique side 113 extending from the side 112 near the connection point to the bottom side 111. The frame body 2 consists of an outer frame 21 forming the entire outer shape of the crystal thin plate, and a horizontal frame 22 in which a large number of the crystal pieces 1 are arranged and connected in the W direction.

The shape of the horizontal frame 22 described above is a straight line parallel to the W direction between adjacent crystal pieces 1-1, and between the two connecting points 211-211 on each crystal piece 1, it is separated from the connecting point 211. Horizontal frame 2 according to
The oblique side 212 where the dimension in the L direction of 2 (that is, the dimension in the width direction of the horizontal frame 22) is smaller, and the oblique side 21 of the two oblique sides 21
It is composed of sides parallel to the W direction between 2 and 212.

To separate each crystal piece 1 from the frame 2, force is applied to the crystal piece 1 in the thickness direction T (hereinafter referred to as the T direction) and the crystal piece 1 is broken off.

(Second Embodiment) A second embodiment of the present invention will be described with reference to the drawings. FIG. 2 is an enlarged view of the main parts of the tuning fork type crystal piece according to the present invention. In the second embodiment, the base 1 of the crystal piece 1
The outer shape near 1 has a smooth curved shape near the point where the side 112 parallel to the W direction and the oblique side 113 intersect in the vicinity of the connection point 211, and the point where the oblique side 113 and the base 111 intersect, and the acute angular shape is removed. ing. By adopting such a shape, it is possible to disperse the concentration of force on the acute angle portion, and it is possible to form a stable crystal piece that is even less susceptible to external forces.

(effect) The effects of the present invention will be explained step by step.

The first effect is that since the oblique side 212 is formed on the horizontal frame 22 of the frame body 2, the connection point 211 is the weakest to external force, and when force is applied, the connection point 211 is the most likely to be separated. Furthermore, the connection point 21 between the frame 2 and the crystal piece 1
1 is located above the base 111 in the L direction, the maximum dimensional accuracy of the crystal piece 1 in the L direction can be almost completely guaranteed (error of 10 μm or less). The second effect is that since the connecting points 211 are provided at two locations including both ends of the tuning fork type piezoelectric element in the W direction, the connection with the frame body is relatively strong compared to the conventional example. The dimension in the W direction can be made extremely small (50 μm). Therefore, mechanical distortion such as minute cracks that occur during separation from the frame can be extremely reduced.
Furthermore, since the connection point 211 includes both ends of the piezoelectric element in the W direction, even if cracks, chips, etc. occur due to mechanical strain, the structure in which the oblique side 212 is provided in the frame 2 can still be used. Eventually, this crack or chip extends outward in the width direction (to the side surface side) of the tuning fork type piezoelectric element, and is contained to the extent that the bottom corner of the piezoelectric element is chipped. Therefore, after connecting the lead terminals as before,
The conductive bonding material at the cracked and chipped portions will not peel off. Therefore, variations in electrical characteristics are extremely small. The third effect is that the connection points 211 are located at both ends in the W direction as described above, so when connecting to the airtight terminal 4, the connection points 211 are connected to the lead wire tip 4.
It is in the position where it is connected and fixed to 1. Therefore, after connecting to the airtight terminal 41, the connection point 211 is mechanically distorted.
Since it is protected by plating metal, its impact resistance is significantly improved. The fourth effect is the connection point 2 as mentioned above.
Since the dimension of the crystal blank 11 in the W direction can be made extremely small, the dimension of the base 111 of the crystal blank 1 in the W direction can be made very large, and can be made almost the same as the maximum dimension of the crystal blank 1 in the W direction. Therefore, positioning when connecting to the airtight terminal 4 can be easily performed, and accuracy in position and direction is also improved.

[Brief explanation of drawings]

FIG. 1a is a front view showing a state in which a tuning fork-shaped crystal piece according to the first embodiment of the present invention is connected to a frame. FIG. 1b is an enlarged front view of the connecting part of the tuning fork-shaped crystal piece to the frame according to the first embodiment of the present invention. Figure 1c
1 is a front view showing a state in which a tuning fork type crystal piece according to a first embodiment of the present invention is connected to an airtight terminal; FIG. FIG. 2 is an enlarged view of the vicinity of the base of a tuning fork-shaped crystal piece according to a second embodiment of the present invention. FIG. 3a is an enlarged front view showing a connection point of a conventional tuning fork-shaped crystal piece with a frame. FIG. 3b is a front view showing a state in which a conventional tuning fork type crystal piece is connected to an airtight terminal. FIGS. 4a and 4b are front views showing another conventional example. 1...Tuning fork-shaped crystal piece, 2...Crystal frame, 3...
Airtight terminal, 4...Lead wire, 11...Tuning fork type crystal piece base, 21...Outer frame of the frame, 22...Horizontal frame of the frame, 23...Connecting portion, 41...Lead wire tip,
111...Base of crystal piece, 115...Minute crack, 116...Crack, crack, 114...Protrusion of crystal piece.

Claims (1)

[Claims for Utility Model Registration] 1. A tuning fork type piezoelectric element that is formed integrally with a frame using photo etching, is obtained by separating from the frame, and has lead terminals connected near both ends in the width direction, The tuning fork type piezoelectric element has two connection points including both ends in the width direction of its base,
The bottom side of the tuning fork type piezoelectric element is formed at a position lower than the two connection points in the longitudinal direction of the tuning fork type piezoelectric element, and the frame between the two connection points of the tuning fork type piezoelectric element is formed at a position lower than the connection point. A tuning fork type piezoelectric element characterized in that it has a shape having sides in which the width of the horizontal frame of the frame body gradually decreases as the width of the horizontal frame becomes smaller as the width of the horizontal frame becomes smaller as the width of the horizontal frame increases. 2. The tuning fork type piezoelectric element according to claim 1, wherein the outer shape from the two connecting points to the bottom of the tuning fork type piezoelectric element is formed by a smooth curve.