JPH0766654A - Piezoelectric vibrator and manufacture therefor - Google Patents

Abstract

PURPOSE:To realize a piezoelectric vibrator which is excellent in characteristic and stability. CONSTITUTION:An opening part of a width b is provided along the node of the vibration of a piezoelectric element and a screen printing is performed for an organic resist 7 by a thickness of t. In the opening part, a coat 3 is formed by a thickness h which is smaller than the t by thermal spraying. This coat 3 is defined as the holding part of the piezoelectric element. Therefore, the sprayed film is difficult to be stuck to the organic resist film 7 and an excellent rectangular sprayed film 3 where the widths of upper and back surfaces are almost the same as shown in a Fig. 2 (b) can be formed. By using the upper surface of this sprayed film 3 as a fixed surface, a piezoelectric vibrator can be excellently held and the stability of the characteristic of the piezoelectric vibrator can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric vibrator using a piezoelectric material such as piezoelectric ceramics, crystal, niobium lithium, and the like. More specifically, it has a conductive protrusion for holding and connecting to an external electrode. The present invention relates to a piezoelectric vibrator having the same and a manufacturing method thereof.

[0002]

2. Description of the Related Art An example of a piezoelectric vibrator using a piezoelectric material such as piezoelectric ceramics, crystal, niobium lithium and the like will be described below with reference to FIGS.

Piezoelectric vibrators used for mechanical filters, oscillators, etc. are made of materials such as piezoelectric ceramics, crystal, niobium lithium, and the like, and an appropriate vibration mode is excited by the piezoelectric effect according to the frequency range used. .

These piezoelectric vibrators are held in the vicinity of the node where the vibration amplitude is 0 so that the vibration of the vibrator is not suppressed, and at the holding portion, they are electrically connected to, for example, a drive power source. , A filter, an oscillator, or the like.

Since these nodes (nodes) are theoretically points or lines having no area, it is ideally desirable to hold the piezoelectric vibrator by points or lines in terms of characteristics. However, in actuality, in order to realize stable holding of the piezoelectric vibrator, the piezoelectric vibrator is held in a dot shape or a linear shape with a certain finite area.

FIG. 5 is a perspective view of a rectangular plate type piezoelectric vibrator made of a piezoelectric material such as piezoelectric ceramic. Driving electrodes 2a and 2b are formed on two main surfaces of the piezoelectric substrate 1 which are opposed to each other. By applying an electric field between the electrodes, longitudinal vibration is excited in the longitudinal direction of the rectangular plate. The vibration node in the length vibration mode is linearly present in the center of the rectangle. Therefore, as shown in FIG. 5, projections 3a and 3b made of a conductive material are formed by thermal spraying along the vibration node.

FIG. 6 shows an outline of a holding structure for a vibrator. The piezoelectric vibrator shown in FIG. 5 has protrusions 3a and 3b.
It is sandwiched and held by the external electrodes 4a and 4b provided inside the outer containers 5a and 5b via the. Furthermore, the external electrodes 4a and 4b are connected to the external terminals 6a and 6b, respectively.

The holding state of the piezoelectric vibrator shown in FIG. 6 will be described with reference to FIG. 7 which is a schematic sectional view in the vicinity of the protrusion 3.
The bottom surface of the protruding portion 3a is attached to and in contact with the electrode 2a, while the top surface of the protruding portion 3a is in contact with the external electrode 4a by being pressed into the external electrode 4a due to external pressure, as in the portion A in the figure. This prevents the protrusions 3a and 3b from being displaced from the external electrodes 4a and 4b.

Such protrusions 3a are generally formed by using a metal mask method. That is, by covering the other portion with a metal mask so that the opening of the metal mask comes to a position on the electrode 2a, the projection as shown in FIG. 7 is formed by spraying a conductive material on the metal mask. The part 3a is formed.

[0010]

However, when the protrusions are formed by the above metal mask method, the following problems occur.

First, since the sprayed film adheres to the mask to be used and the opening of the mask is gradually closed, the mask becomes disposable after several times in the worst case, resulting in a short mask life and a high production cost. Was holding.

Secondly, as shown in FIG. 7, the shape of the formed protrusion is such that the width a of the upper surface portion is narrower than the width b of the bottom surface portion and both side surfaces are sloped. If the value is narrow, the piezoelectric vibrator tilts like a seesaw, and the vibrating portion such as the tip of the vibrator comes into contact with the external electrodes 4a, 4b, etc., and the vibration characteristics deteriorate. Therefore, it takes time to assemble and adjust, which is a problem of improving productivity.

The upper surface width a is set so that the piezoelectric vibrator does not tilt.
However, there is a problem in that the bottom width b is also increased by widening, and the protrusion itself deteriorates the vibration characteristics of the piezoelectric vibrator this time.

As described above, according to the conventional structure and method, it has been impossible to provide the protruding portion for stably holding the piezoelectric vibrator with high productivity and at low cost.

[0015]

According to the invention of claim 1 of the present application, the electrodes of the piezoelectric substrate are provided in the vicinity of the node points of the piezoelectric substrate provided on the two surfaces facing the driving electrode. On the surface to be formed or on the electrode surface, a resist film having a required pattern opening is formed, and a conductive material is sprayed to the opening to a required thickness, and then the resist is peeled off to form a conductive sprayed coating projection. A method of manufacturing a piezoelectric vibrator, comprising forming a portion.

According to a second aspect of the present invention, a piezoelectric substrate, driving electrodes provided on two surfaces of the piezoelectric substrate facing each other, and the electrode provided near a node point of the piezoelectric substrate. A resist film having a required pattern opening is formed on the surface or the electrode surface, and a conductive material is sprayed to the opening to a required thickness, and then the resist is peeled off to form a patterned conductive film. A piezoelectric vibrator comprising: a sprayed coating projection portion; and an external electrode that holds the piezoelectric substrate, the piezoelectric substrate being in contact with the piezoelectric substrate via the projection portion.

According to a third aspect of the present invention, the piezoelectric substrate, the driving electrodes provided on two opposing surfaces of the piezoelectric substrate, and the electrode provided near the node point of the piezoelectric substrate are provided. In a piezoelectric vibrator in which the piezoelectric substrate is held in contact with an external electrode through a conductive protrusion provided on the surface or the electrode surface, the area of the surface of the protrusion that is bonded to the oscillator and faces. Is smaller than the area of the surface in contact with the external electrode.

[0018]

According to the first aspect of the present invention, since the projection of the piezoelectric vibrator does not use a metal mask, it can be manufactured at low cost. Further, since the resist mask can make the width of the opening narrower than that of the metal mask, it is possible to form a projection having a desired narrow width. Further, since the resist mask is in close contact with the electrode or the surface of the substrate, even if the thickness of the protruding portion is increased, the protruding portion of the sprayed coating can be formed without the sagging of the sprayed particles at the time of spraying and the sagging of the cross-sectional shape.

According to the second aspect of the invention, the cross-sectional shape of the protrusion does not sag, and the area in contact with the external electrode can be secured as compared with the conventional case even if the contact area of the protrusion on the piezoelectric substrate side remains the same. The piezoelectric substrate is hard to tilt with respect to the external electrode, and the vibrating portion of the piezoelectric substrate does not hit the external electrode or the like.
Therefore, the stability of the vibration characteristics of the piezoelectric vibrator can be improved. Furthermore, since the posture adjustment of the piezoelectric substrate during assembly becomes easy, a piezoelectric vibrator capable of improving productivity can be realized.

According to the third aspect of the present invention, the area of the bottom surface of the protrusion, that is, the surface of the side that contacts the piezoelectric substrate is kept the same, and the area of the side that contacts the external electrode is secured wider than the bottom surface. Therefore, the piezoelectric substrate is less likely to tilt with respect to the external electrode, and the vibrating portion of the piezoelectric substrate does not hit the external electrode or the like. Further, by widening the area of the top surface and narrowing the area of the bottom surface, the adverse effect on the vibration of the piezoelectric substrate can be further reduced. Therefore, the vibration characteristics of the piezoelectric vibrator can be improved and the stability of the characteristics can be improved. further,
Since it becomes easy to adjust the posture of the piezoelectric substrate when assembling, a piezoelectric vibrator capable of improving productivity can be realized.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIGS.
It will be described based on 4. It should be noted that components having the same or equivalent functions as those of the conventional example are designated by the same reference numerals, and detailed description thereof will be omitted.

A first embodiment of the present invention will be described with reference to FIGS.
Will be explained. FIG. 1 is a cross-sectional view of the vicinity of a protrusion in the piezoelectric element of this example. FIG. 2 is a diagram showing a procedure for forming the protrusion.

1 and 2, 1 is a piezoelectric ceramic,
A piezoelectric substrate 2 made of crystal, niobium lithium, or the like, 2 and Ag, A provided on the piezoelectric substrate 1 by vapor deposition or printing.
A drive electrode made of a metal such as u or Cu, 3 is a protrusion made of a metal such as Mo or NiCr provided on the drive electrode 2 by a thermal spraying method, and 7 is an organic substance having an opening provided on the drive electrode 2. Is a resist mask of.

The protrusion formed in FIG. 1 will be described. Here, Cu is used for the external electrode 4, and Mo that is harder than Cu is used for the protrusion 3. The reason why the protrusions 3 are formed by the thermal spraying method is that the surface of the thermal spray coating is rough and it is easy to form fine irregularities. As a result, as shown in FIG.
The fine irregularities due to the surface roughness of the electrodes contact the external electrodes 4 so as to bite into the external electrodes 4 so that the piezoelectric substrate 1 is not easily displaced at the contact portions.

A method of forming protrusions on the piezoelectric substrate in this embodiment will be described with reference to FIG. Figure 2 (a) shows
FIG. 6 is a cross-sectional view showing a state where an organic resist mask 7 having an opening having a width b and a height t is formed on the drive electrode 2. The resist mask 7 is formed by screen printing here. The reason why the resist mask 7 is made of an organic substance is, firstly, because it is desired to utilize the property that the sprayed film is generally difficult to adhere to a relatively soft substance such as an organic substance. Secondly, the resist mask 7 can be completely peeled off and removed by the peeling liquid or the like without damaging the drive electrodes 2, the protrusions 3, and the like.

Further, FIG. 2B shows a state in which after the resist mask 7 is formed, thermal spraying is performed from above to have a thickness h (h is t or less) of the thermal spray coating. As shown in the figure, the sprayed coating hardly adheres to the resist mask 7 as a film, and the sprayed particles adhere to the resist mask 7 sparsely like the Q portion. Therefore, as shown in the drawing, the sprayed coating is deposited only on the opening of the resist mask 7, and the deposited coating forms the protrusion 3.

Lastly, FIG. 2 (c) shows a state in which the resist mask 7 is stripped by the resist stripping solution. The resist mask 7 is completely removed, and the sprayed coating formed on the opening is formed as the protrusion 3. The shape of the protrusion is the same as the shape of the opening of the resist mask 7 without the side surface being sagged. In this way, the protrusion as shown in FIG. 1 can be formed.

As described above, by using an inexpensive resist mask without using the conventional metal mask, the protrusion can be stably manufactured at low cost.

Further, by forming the protrusions as described above, there is no sagging that occurs in the conventional protrusion shown in FIG. 7, and the width a of the upper surface is substantially equal to the width b of the bottom, that is, The width of the upper surface is wider than in the conventional case, and the piezoelectric substrate 1 is less likely to tilt with respect to the external electrode 4. Therefore, since the external electrode 4 and the like do not come into contact with the vibrating portion of the piezoelectric substrate 1, the characteristics and stability of the piezoelectric vibrator are improved.

Next, a second embodiment will be described with reference to FIG. Here, an example will be described in which the width a of the upper surface of the projection is larger than the width b of the bottom surface. The need for such protrusions is due to the following reasons. First, in order to reduce the influence on the vibration of the piezoelectric substrate, it is desired to make the width or area of the bottom surface of the protrusion as narrow as possible. Secondly, the width or area of the upper surface of the protrusion should be made as wide as possible in order to prevent the vibrating portion from coming into contact with the external electrode or the like due to the piezoelectric substrate tilting or moving with respect to the external electrode. An example of forming this protrusion is shown in FIG.
Shown in (a), (b) and (c). These are shown in Fig. 2 (b).
It corresponds to the state of the manufacturing process shown in.

The difference from the first embodiment is that the width of the opening of the resist mask 7 is wider in the upper part than in the bottom part.

The width of the bottom of the opening of the resist mask 7 may not be narrower than the width of the upper portion of the resist mask 7, as in the following embodiment. That is, in FIGS. 4 (a) and 4 (b),
The state of the manufacturing process corresponding to FIGS. 2B and 2C is shown, respectively. The difference is that the thickness h of the protrusion 3 is higher than the thickness t of the resist mask 7, that is, t <h.

If it is difficult for the thermal spray coating to adhere to the resist mask 7, if t <h in this way, the projection 3 made of the thermal spray coating has a thickness h exceeding t and
The width of the exceeded portion becomes d wider than the resist mask opening width b, and the width a of the upper surface also becomes wider. Therefore, it is possible to form the protrusion 3 having a width a of the upper surface that is wider than the width b of the bottom surface.

The resist ink used here is, for example, an organic solvent release plating resist X87 manufactured by Taiyo Ink Mfg. Co., Ltd., but depending on the desired opening width b, resist film thickness t, heat resistant temperature, etc. It is necessary to select it in a timely manner, and the selection is not limited. In short, the sprayed film is hard to adhere, and can be completely peeled and removed with a peeling liquid or the like without damaging the drive electrodes 2 and the protrusions 3, and the width and thickness of the opening can be set to desired values. I wish I had it.

The resist mask is not limited to the above example,
You may use a dry film, a photoresist, etc. In this case, the pattern of the openings is formed by using a method such as photolithography.

Although the projection 3 is formed on the drive electrode 2 in each of the above embodiments, the drive electrode 2 may be formed after the projection 3 is formed on the piezoelectric substrate 1.

The drive electrode 3 may be formed not only by the above method but also by a thermal spraying method.

[0038]

According to the present invention, a piezoelectric vibrator having excellent characteristics and high stability can be realized at a lower cost than before, and high productivity can be easily realized.

[Brief description of drawings]

FIG. 1 is a sectional view of a main part in a first embodiment of the present invention.

FIG. 2 is a manufacturing process chart of the embodiment.

FIG. 3 is an explanatory view of a protrusion forming step in the second embodiment of the present invention.

FIG. 4 is an explanatory view of a protrusion forming step in the third embodiment of the present invention.

FIG. 5 is a perspective view showing a schematic configuration of a piezoelectric vibrator used for explaining a conventional example.

FIG. 6 is a schematic cross-sectional view showing a holding structure of a piezoelectric vibrator used for explaining a conventional example.

FIG. 7 is a schematic view of a holding portion of a conventional piezoelectric vibrator.

[Explanation of symbols]

 1 Piezoelectric Substrate 2 Drive Electrode 3 Projection 4 External Electrode 5 Holding Substrate 7 Resist Mask

Claims (3)

[Claims] 1. A required pattern opening is provided on a surface of an electrode of the piezoelectric substrate or a surface of the electrode near the node point of the piezoelectric substrate provided on two surfaces facing the driving electrode. Forming a resist film having, and further spraying a conductive material to the opening to a required thickness, peeling the resist, forming a conductive sprayed film projections Production method. 2. A piezoelectric substrate, driving electrodes provided on two opposing surfaces of the piezoelectric substrate, and a surface near the node point of the piezoelectric substrate on which the electrode is provided or the electrode surface. In, a resist film having a required pattern opening is formed, a conductive material is sprayed to the opening to a required thickness, and then the resist is peeled off to form a patterned conductive sprayed coating projection, and A piezoelectric vibrator, comprising: an external electrode that is in contact with the piezoelectric substrate via the protrusion and holds the piezoelectric substrate. 3. A piezoelectric substrate, driving electrodes provided on two opposing surfaces of the piezoelectric substrate, and a surface on which the electrode is provided or a surface of the electrode near a node point of the piezoelectric substrate. Via the conductive protrusion provided on the
In the piezoelectric vibrator in which the piezoelectric substrate is in contact with and held by an external electrode, the area of the surface of the protrusion that is in contact with the vibrator is smaller than the area of the surface in contact with the external electrode. Piezoelectric vibrator.