JPH06334460A - Manufacture of chip type piezoelectric resonator - Google Patents

Abstract

PURPOSE:To form an outer package resin with a smooth outer face without causing dispersion in the thickness in the manufacture of the chip type piezoelectric resonator possible for surface mounting whose outer package is made of a resin. CONSTITUTION:A mother substrate 21 formed by forming plural piezoelectric resonator on a piezoelectric substrate is fitted in a frame 31 and the frame 31 is placed on a vibration table 42 and while applying vibration to the frame 31, a thermosetting outer package resin 34 is ejected into the frame 31 in the non-curing state so as to cover both major sides of the mother substrate 21. Then the outer package resin 34 is cured and the mother substrate 21 covered with the outer package resin 34 is divided to obtain plural chip type piezoelectric resonators.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a chip type piezoelectric resonator used as a chip type filter, an oscillator, a discriminator, or the like.

[0002]

2. Description of the Related Art Piezoelectric resonators conventionally used as filters, oscillators, and discriminators have generally been leads.

However, in recent years, surface mounting technology (SMD) has been adopted in order to miniaturize electronic devices, and along with this, this type of piezoelectric resonator also has a chip type without a lead wire. Is required. A specific example of such a chip type piezoelectric resonator will be described with reference to FIGS.

As shown in FIGS. 10 to 12, the piezoelectric resonator 1 includes a piezoelectric substrate 2. Divided vibrating electrodes 3 and 4 are formed on one main surface of the piezoelectric substrate 2,
On the other main surface, a vibrating electrode 5 facing the vibrating electrodes 3 and 4 is formed. These vibrating electrodes 3, 4 and 5
To the terminal electrodes 6, 7 and 8, respectively,
These terminal electrodes 6 to 8 are located at the edges of the piezoelectric substrate 2.

This piezoelectric resonator 1 is an energy trap type dual-mode piezoelectric resonator utilizing a thickness extensional vibration mode, which has divided vibration electrodes 3 and 4 and a vibration electrode 5 facing them. On both sides of the piezoelectric substrate 2,
Resin plates 11 and 12 made of polyphenylene sulfide (PPS) having cavities 9 and 10, respectively, are arranged at locations corresponding to the vibrating electrodes 3 to 5, and are bonded to the piezoelectric substrate 2 by adhesives 13 and 14. Further, as shown in FIG. 12, external electrodes 15, 16 and 71 are formed on the outer surface of the piezoelectric resonator 1,
It is electrically connected to the terminal electrodes 6, 7 and 8, respectively.

Such a chip-type piezoelectric resonator 1 has the advantages that it is small and can be surface-mounted.

[0007]

However, although the resin plates 11 and 12 are bonded to the piezoelectric substrate 2 with the adhesives 13 and 14, the bonding strength is relatively weak, and as a result, the vibration of the piezoelectric resonator 1 occurs. There is a problem in that the effect of suppressing spurious by suppressing unnecessary vibrations in parts other than the parts does not appear.

Further, since the adhesives 13 and 14 are used, there is a problem that moisture easily enters from the interface between the piezoelectric substrate 2 and the resin plates 11 and 12, and the moisture resistance is poor.

Therefore, an object of the present invention is to provide a method of manufacturing a chip type piezoelectric resonator which can solve the above-mentioned problems.

[0010]

The method for manufacturing a chip type piezoelectric resonator according to the present invention is characterized by including the following steps in order to solve the above-mentioned technical problems.

That is, first, a mother substrate is prepared on which a plurality of piezoelectric resonance elements each including a vibrating electrode facing each other with the piezoelectric substrate sandwiched therebetween and terminal electrodes connected to the vibrating electrodes are prepared. Further, a frame is prepared in which the mother substrate can be fitted, and in which the mother substrate is provided with a concave portion whose bottom faces are both main surfaces of the mother substrate. Then, the mother board is fitted into the frame, and in that state, while applying vibration to the frame, a thermosetting exterior resin is poured into the frame in an uncured state so as to cover both main surfaces of the mother board. After curing, the mother substrate covered with the exterior resin is divided into individual piezoelectric resonance elements so that the terminal electrodes are exposed on the division surfaces, and a plurality of chip-type piezoelectric resonators are obtained.

[0012]

According to the present invention, the exterior resin is applied so as to cover both main surfaces of the mother substrate in an uncured state, and is cured in that state. Therefore, a large adhesive strength can be obtained between the exterior resin and the mother substrate, and as a result, unnecessary vibrations other than the vibration part of the piezoelectric resonator can be sufficiently suppressed. Moreover, the humidity resistance of the obtained piezoelectric resonator can be improved.

Further, in the present invention, when the thermosetting exterior resin is poured into the frame so as to cover both main surfaces of the mother substrate, vibration is applied to the frame. Therefore, the exterior resin is
It spreads smoothly in the frame, and its surface can be made smooth without any depression or the like.

As a result, the amount of the exterior resin poured into the frame can be fixed without any problem. Therefore, by fixing the amount of the exterior resin in this manner, the exterior resin can be mechanically poured. Therefore, the pouring process can be efficiently advanced. Further, by fixing the amount of the exterior resin that is poured, the thickness of the exterior resin that covers the mother substrate can be suppressed from varying among products. Also, due to the vibration applied when the exterior resin is poured,
It is also possible to suppress variations such that the thickness of the exterior resin is partially different in one product. as a result,
In order to improve the dimensional accuracy and flatness in the thickness direction of the chip-type piezoelectric resonator to be obtained, when polishing the outer surface of the exterior resin after curing, it will not be polished or not be polished. Not only can it be improved, but also the efficiency of the polishing work can be improved. Further, the outer surface of the exterior resin is smoothed by the vibration when the exterior resin is poured, and the thickness of the exterior resin can be made uniform by making the exterior resin poured into a constant level. May not be required.

Further, according to the present invention, since the mother substrate covered with the exterior resin is finally divided to obtain a plurality of chip type piezoelectric resonators, a large number of chip type piezoelectric resonators can be efficiently obtained. it can.

[0016]

1 is a perspective view showing a chip type piezoelectric resonator 20 obtained by a manufacturing method according to an embodiment of the present invention. In order to obtain such a piezoelectric resonator 20, the steps shown in FIGS. 2 to 7 are performed.

First, as shown in FIG. 2, a mother substrate 21
Is prepared. A part of the mother substrate 21 is enlarged and shown in FIG. The mother substrate 21 is provided with a piezoelectric substrate 22 made of piezoelectric ceramic. Divided vibrating electrodes 23 and 24 are formed on one main surface of the piezoelectric substrate 22, and these vibrating electrodes 23 and 24 are formed on the other main surface. The vibrating electrode 25 is formed so as to face the. Vibrating electrode 2
3, 24 and 25 have terminal electrodes 26, 2 respectively.
7 and 28 are connected. These one set of vibrating electrodes 23
25 to 25 and the terminal electrodes 26 to 28 constitute one piezoelectric resonance element 29, and the mother substrate 21 provides a plurality of piezoelectric resonance elements 29.

The piezoelectric resonance element 29 is composed of divided vibration electrodes 23 and 24 and a vibration electrode 25 facing them.
Is a dual mode piezoelectric resonator of energy trapping type utilizing a thickness longitudinal vibration mode, and in order to secure a vibration space thereof, a cavity forming material 30 made of, for example, wax for forming a cavity is used as a piezoelectric resonance element 29. Each vibration area,
That is, the vibrating spaces 23 and 24 and the vibrating electrode 25
Are applied to cover each. However, the structure and the form of the piezoelectric resonance element provided by the mother substrate are arbitrary, and for example, an energy trap type resonator utilizing the thickness shear vibration mode may be used. A rubber-like elastic body such as silicone rubber may be provided to provide damping.

On the other hand, as shown in FIG. 4, a frame 31 made of, for example, resin is prepared in which the above-mentioned mother substrate 21 can be fitted almost exactly. This frame 31 has a temperature (for example, 150 ° C.) at the time of heat curing of the exterior resin described later.
It is taken into consideration that it does not deform or melt. Further, when the outer side surface 32 of the frame 31 is used as a reference plane for cutting, which will be described later, it is desirable that the flatness is good.

Further, it is preferable to provide the frame 31 with a means for fixing the mother substrate 21 to be inserted therein at substantially the center of the frame 31 in the thickness direction. In this example,
The shelves 33 are provided inside the opposite sides (for example, short sides) of the frame 31.

As shown in FIG. 5, the mother substrate 2 described above is used.
1 is fitted in the frame 31, and in that state, the uncured exterior resin 3 is formed on one surface of the mother substrate 21 as shown in FIG.
4 is poured.

When pouring the uncured exterior resin 34 as described above, the frame 31 is placed on the vibration table 42 which is vibrated by the vibrator 41. In this way, the exterior resin 34 poured into the frame 31 while vibrating the frame 31 smoothly spreads in the frame 31 and forms a smooth surface. At this time, the exterior resin 3 that is poured
The amount of 4 may be fixed so that the exterior resin 34 always has a constant thickness.

As the exterior resin 34, for example, an epoxy thermosetting resin which is liquefied by a solvent is used, and an appropriate amount of filler such as silica or talc is added thereto. The exterior resin 34 is dried by, for example, natural drying, and after the exterior resin 34 does not flow out even if the frame 31 is inverted together with the mother substrate 21, the frame 31 is inverted together with the mother substrate 21 and the exterior resin 34. In the state, in the same manner as described above, the frame 3
While applying vibration to 1, on the other surface of the mother substrate 21,
The exterior resin 34 is poured again. This exterior resin 34
Are also naturally dried, for example.

Next, the exterior resin 34 poured in two steps as described above is heated at 150 ° C. for 30 minutes, for example.
Heat cured. At this time, the cavity forming material 30 described above
Migrate into the exterior resin 34, and as a result, a cavity for the vibration space is formed.

Next, in order to further improve the dimensional accuracy in the thickness direction and the flatness of the chip-type piezoelectric resonator 20 (FIG. 1) to be obtained, the outer surface of each of the exterior resins 34 is, together with the frame 31, if necessary. To be polished. This polishing is performed, for example, by rubbing polishing using a polishing plate.
As a result, a sandwich structure 35 in which both surfaces of the mother substrate 21 are covered with the exterior resin 34 as shown in FIG. 7 is obtained.

Next, as shown in FIG. 7, the sandwich structure 35, together with the frame 31, is attached to the outer surface 32 of the frame 31.
Is taken as a reference plane and cut along the cutting lines 36 and 37. By this cutting, the mother substrate 21 is divided into individual piezoelectric resonance elements 29, and the terminal electrodes 26 to
28 is exposed on the cut surface. In this way, the chip-type piezoelectric resonator 20 as shown in FIG. 1 is obtained.

The steps of polishing and cutting described above are
It may be implemented with the sandwich structure 35 taken out from the frame 31.

Next, as shown in FIG. 8, an external electrode 38 which is electrically connected to each of the terminal electrodes 26 to 28 is formed on the surface of the chip type piezoelectric resonator 20 where at least the terminal electrodes 26 to 28 are exposed. ~ 40 are applied, for example by printing and baking a conductive paste.

In this embodiment, all the terminal electrodes 26 to 28 of the chip type piezoelectric resonator 20 are exposed on the same surface. However, such terminal electrodes may be exposed on different surfaces. In that case, external electrodes may be provided on each of these surfaces.

Further, as shown in FIG. 9, an external electrode 38 which is electrically connected to the terminal electrodes 26 to 28 of the chip type piezoelectric resonator 20.
The a, 39a, and 40a may be formed not only on one side surface of the chip-type piezoelectric resonator 20 but also on at least one of the upper and lower surfaces, and further on the other side surface. By doing so, when the chip-type piezoelectric resonator 20 is mounted on the circuit board, soldering thereof can be reliably achieved. Note that, of the external electrodes 38a to 40a, the portions formed on the upper surface and / or the lower surface of the chip-type piezoelectric resonator 20 are printed in advance with a conductive paste, printed, etc. in the state of the sandwich structure 35 shown in FIG. It may be given by the method of.

[Brief description of drawings]

FIG. 1 is a perspective view showing an external appearance of a chip type piezoelectric resonator 20 obtained according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a mother substrate 21 prepared to obtain the chip-type piezoelectric resonator 20 shown in FIG.

3 is an enlarged perspective view showing a part of the mother board 21 shown in FIG.

4 is a perspective view showing a frame 31 used for obtaining the chip-type piezoelectric resonator 20 shown in FIG.

5 is a perspective view showing a state where the mother board 21 shown in FIG. 2 is fitted into the frame 31 shown in FIG.

6 is an exterior resin 34 on the mother substrate 21 shown in FIG.
It is a perspective view showing the state of pouring.

7 is a perspective view for explaining a cutting step of a sandwich structure 35 obtained after curing the exterior resin 34 shown in FIG.

8 is a perspective view showing a state where external electrodes 38 to 40 are formed on the chip-type piezoelectric resonator 20 shown in FIG.

9 is a perspective view showing a state in which external electrodes 38a to 40a are formed on the chip-type piezoelectric resonator 20 shown in FIG.

FIG. 10 is an exploded perspective view showing elements included in a conventional chip-type piezoelectric resonator 1.

11 is a sectional view of the chip-type piezoelectric resonator 1 shown in FIG.

12 is a perspective view showing the external appearance of the chip-type piezoelectric resonator 1 shown in FIG.

[Explanation of symbols]

 20 Chip Type Piezoelectric Resonator 21 Mother Substrate 22 Piezoelectric Substrate 23-25 Vibration Electrode 26-28 Terminal Electrode 29 Piezoelectric Resonance Element 31 Frame 34 Exterior Resin 36, 37 Cutting Line 38-40, 38a-40a External Electrode 41 Vibrator 42 Vibration Table

Claims (1)

[Claims] 1. A mother substrate on which a plurality of piezoelectric resonance elements each including a vibrating electrode facing each other with the piezoelectric substrate sandwiched therebetween and a terminal electrode connected to each of them are prepared, and the mother substrate is fitted into the mother substrate. It is possible to prepare a frame for forming recesses having bottom surfaces of both main surfaces of the mother board in a fitted state, and fitting the mother board in the frame, and in that state, vibration is applied to the frame. While adding, a thermosetting exterior resin is poured in an uncured state in the frame so as to cover both main surfaces of the mother board, and after curing the exterior resin, the mother board covered with the exterior resin is A method of manufacturing a chip-type piezoelectric resonator, comprising: each step of dividing each of the piezoelectric resonance elements so that the terminal electrode is exposed at a division surface to obtain a plurality of chip-type piezoelectric resonators.