JPS5838004B2 - Piezoelectric element parts - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to piezoelectric components such as energy trapping ceramic filters.

Conventionally, in order to obtain a piezoelectric element component that is an exterior of a piezoelectric element with electrodes that constitutes a ceramic filter as described above, the piezoelectric element is heated to a predetermined temperature and immersed in powder such as epoxy resin. However, in this method, it is necessary to protect the working electrode part or to form a gap so that the coating resin does not come into direct contact with the working electrode part.

Japanese Patent Publication No. Sho 50-23780 proposes a method for controlling voids, but in this method, partially removing the adhesive layer is complicated and time-consuming, and the removal contour is unclear. However, it is difficult to obtain a certain thickness by applying an adhesive layer.

In addition, it is difficult to obtain an adhesive layer with a thickness of several hundred microns or more, and a gap of several tens of microns causes the problem that the substrate with the adhesive layer easily comes into contact with the electrode surface due to external force or temperature changes. There is.

The present invention solves such problems and will be explained below with reference to the drawings shown as examples.

Example 1 In FIG. 1, 1 is a piezoelectric element constituting an energy trapping ceramic filter, which has input and output electrodes 2 and 3 on one main plane of a square piezoelectric substrate 1a, respectively. , and a grounding electrode (common electrode) 4 is arranged facing each other in a pattern as shown in the figure on the other main plane.

Further, the piezoelectric element 1 has an insulating substrate 5 on which conductors 2', 3', and 4' in a predetermined pattern are provided on one main plane.
Each conductor 2/,
3/, 4/ and each electrode 2, 3.4 of the piezoelectric element 1 are:
Each is connected in electrical continuity.

Furthermore, each conductor 2/, 3/, on the insulator substrate 5
External connection terminals 6a, 6b, and 6c are attached to the ends of 4/ with solder 7 or the like.

The insulating substrate 5 is a printed board made of a resin such as phenol, epoxy, or polyimide, with copper foil adhered to its surface, and is etched into a predetermined pattern to form the conductors 2', 3', 4. It is possible to use one in which a predetermined conductive film pattern is formed on a ceramic or glass substrate such as steatite or alumina by means of plating, vapor deposition, baking, or the like.

FIG. 2 shows a partially cutaway front view when a spacer 9 and a lid 12, which will be described later, are mounted on the insulator substrate 5 on which the piezoelectric element 1 shown in FIG. 1 is mounted, and FIG. A first covering layer 14 made of an insulating member, that is, a rubber member from above.
and a cross-sectional view when the second coating layer 15 made of thermosetting resin is sealed and packaged.

FIG. 4 is a perspective view showing an example of the spacer 9, which is made by attaching a thermosetting or pressure-sensitive adhesive layer 10 made of an insulating material to both sides of a rectangular base material such as a polyester film. , a hole 1 for accommodating the piezoelectric element 1 described above and forming a predetermined gap 11 as shown in FIG.
6 is drilled.

Further, the spacer 11 has a thickness larger than the thickness of the piezoelectric element 1 by a predetermined amount.

FIG. 5 is a perspective view showing an example of the lid body 12, which is extremely flexible and made of a conductive member such as aluminum foil or copper foil with a thickness of 4 μm to 6 μm, for example, and one side of the lid body 12 is A pressure-sensitive conductive adhesive 13 is applied; it is processed into a predetermined convex shape.

The exterior structure of the present invention uses the spacer 9 and the lid 12 described above, and the assembly process will be explained with reference to FIGS. 2 and 3.

First, a spacer 9 is placed on the insulator substrate 5 on which the piezoelectric element 1 is attached.
Attach.

In this case, as is clear from FIG.
The piezoelectric element 1 is placed at a predetermined position such that the peripheral edge of the piezoelectric element 6 surrounds the outer periphery of the piezoelectric element 1.

As for the external dimensions of the spacer 9, it is desirable that the width is approximately the same as that of the insulating substrate 5, and the length is such that it does not overlap the external connection terminals 6at6b, 6c.

After pasting the spacer 9, the lid 12 is stacked and pasted onto the spacer 9 with the pressure-sensitive adhesive layer 10 facing upward so as to cover the hole 16 of the spacer 9.

After attaching the lid 12 to the spacer 9, the lid 12 is attached to the spacer 9.
2 along the side surface of the spacer 9,
It is also attached to the conductor 4' portion on the ground side of the insulating substrate 5.

In this way, the lid 12 and the ground conductor 4' are electrically connected, and the lid 12 has a shielding effect on the piezoelectric element 1.

After forming a predetermined gap 11 in the working electrode portion of the piezoelectric element 1 as described above, the adhesive layer of the spacer 9 is heated and hardened, and then, as shown in FIG. ) etc., the entire insulating substrate 5 including the piezoelectric element 1, spacer 9, and lid 12 is immersed, and then the applied silicone rubber is heated and cured to form a first coating layer 14 made of a rubber member. .

After that, the second resin layer 15 is further immersed in a thermosetting powder such as epoxy resin or a liquid resin layer that hardens at room temperature.
By forming and heating and curing at a predetermined temperature,
The piezoelectric element 1 can be kept in a sealed state completely isolated from the outside air.

Note that the first covering layer 14 is formed to alleviate mechanical shock and thermal shock to the piezoelectric element, and the material of the rubber member layer is arbitrary.

Of course, if necessary, the first coating layer 14 described above may be omitted and the thermosetting resin layer, that is, the second coating layer 15 may be directly applied.
Needless to say, it may be covered in a sealed state only by using a coating.

Example 2 As in Example 1, first, a spacer 9' shown in FIG. 7 is bonded to the insulator substrate 5 shown in FIG. 1 on which the piezoelectric element 1 is attached.

In this case as well, the piezoelectric element 1 is positioned within the hole 16 of the spacer 9'.

The spacer 9l shown in FIG. 7 has the same shape as the spacer 9 shown in FIG.
0' is attached, and it has sufficient adhesiveness even at room temperature.

After pasting such a spacer 9', a cover 12' as shown in FIG. Paste over the agent layer.

Note that, unlike in Example 1, the lid body 12' does not have a pressure-sensitive conductive adhesive layer formed on one side, and is preferably made of a flexible thin film material such as aluminum foil, polyimide film, or polyester film.

In that case, the thickness of the thin film member is experimentally determined to be 4μ to 25μ.
The range of m had the best workability, and fewer pinball defects occurred during the painting process.

After attaching the lid 12' via the spacer 9' so as to cover the piezoelectric element 1 on the insulating substrate 5 as described above,
A predetermined pressing load is applied to the lid 12' using a pressing jig (not shown) that has a predetermined recess formed therein so as not to damage the piezoelectric element 1, and the spacer 9' is heated at a predetermined temperature for a predetermined time to make the spacer 9' stick. The agent layer 10' is cured.

By curing the adhesive layer 10', the insulating substrate 5 and the lid 12 are bonded together.
', and a predetermined gap 11 is formed in the working electrode portion of the piezoelectric element 1.

After that, in order to further keep the piezoelectric element 1 sealed from the outside air, a resin coating layer 1 is coated with a thermosetting resin such as an epoxy resin.
5' is formed to complete the sheathing of the piezoelectric element.

In this second embodiment as well, a conductive material such as aluminum foil is used as the lid 12', and the lid 12' and the insulating substrate 5 are
Considering the characteristics of the piezoelectric element, it is desirable to electrically connect the upper ground-side conductor 4' with a conductive adhesive or the like so that the lid 12' has a shielding effect.

As mentioned above, in the piezoelectric element component of the present invention, by using the spacer and the lid, a void of any size can be formed in the actuating electrode portion easily and efficiently at low cost, and the piezoelectric element component of the present invention can have stable electrical characteristics. Piezoelectric element parts can be obtained.

Note that the material of the spacer used in the above examples does not have to be double-sided adhesive tape; instead, it can be an insulating material tape that has adhesiveness on only one side, paper formed into a predetermined shape, plastic film, etc., coated with adhesive. Alternatively, a hot-melt adhesive sheet or a solvent-activated adhesive sheet made of B-stage prepreg resin or the like may be punched into a predetermined shape.

Furthermore, the shape of the hole in the spacer may be arbitrary, such as an ellipse or a rectangle.

Further, the shape and material of the lid body are also arbitrary, and the lid body is not limited to metal foil having a conductive adhesive, but may be formed only from a metal foil alone or a thin film member such as a resin film.

In particular, polyimide films and polyester films with a resin film thickness of about 4 μm to 25 μm are ideal as cover materials, and as mentioned above, when the piezoelectric element is covered with thermosetting resin, it has a remarkable effect in preventing pinholes. Indicated.

The reason is as follows.

That is, when applying the thermosetting resin coating, it is necessary to heat the piezoelectric element to a predetermined temperature, and the heating of the piezoelectric element causes the air present in the gap 11 to expand.

Here, if the adhesive strength of the spacer is weak, the expanded air in the gap portion leaks out of the gap forming portion, pierces the thermosetting resin film, and creates pinholes.

However, in the case of the thin resin film mentioned above, the resin film itself expands when heated, and since it is a flexible thin film, it deforms and stretches arbitrarily, and the lid acts like a diaphragm, causing the air in the gap to thermoset. This is because it prevents it from being mixed into the resin.

In addition, in this case, if the constituent parts of the lid are made transparent, the piezoelectric element after the gap is formed can be observed through the lid, so there is no possibility of cracks or cracks in the piezoelectric element or the conductive adhesive connections. This is effective in checking for defects, etc.

Further, the present invention is not limited to a structure in which a piezoelectric element is attached to an insulating substrate as shown in 5 above, but as shown in FIG. 9, the main surface of a piezoelectric substrate 1a' Extend parts 2A, 3A, 4A of the electrodes 2, 3, 4 to be attached to the terminals, and attach external connection terminals (3a, 6b,
This also includes the case where a piezoelectric element 1' configured by directly connecting 6C is used.

In this case, for example, a spacer 9 or 9l as illustrated in FIG. 4 or FIG. Lid body 12 as shown in FIG. 5 or FIG. 8
Alternatively, the parts 12' may be bonded together and the whole may be hermetically covered with an insulating material as shown in FIG. 3 or FIG. 6.

In this case, as in the previous embodiment, the lid body is formed of a conductive member, and this is electrically connected to the electrode on the ground side of the piezoelectric element to provide a shield. Furthermore, it is effective to use a first covering layer made of a rubber member as illustrated in FIG. 3 and a second covering layer made of a thermosetting resin as an insulating member for the exterior.

[Brief explanation of drawings]

Fig. 1 is a front view of essential parts of an embodiment of the present invention in an unexposed state, Fig. 2 is a partially cutaway front view of the embodiment, Fig. 3 is a sectional view of the embodiment, and Fig. 4 is a main part of the present invention. FIG. 5 is a perspective view of an example of a lid body used in the present invention, FIG. 6 is a sectional view of another embodiment of the present invention, and FIG. 7 is a perspective view of an example of a spacer used in the present invention. FIG. 8 is a perspective view of another example of the spacer used in the present invention, FIG. 9 is a front view of another example of the piezoelectric element that can be used in the present invention. be. 1, 1'... Piezoelectric element, 2, 3, 4...
・Electrode, 2'3', 4/-... Conductor, 5...
... Insulator board, 6a, 6b6c ... External connection terminal, 7 ... Solder, 8 ... Conductive adhesive, 9, 9' ... ...Spacer, 1 0,
1 0'... adhesive layer, 11... void, 1 2 , 1 2'... lid body, 13...
... Conductive adhesive, 14... First coating layer, 15... Second coating layer, 16... Hole.

Claims (1)

[Claims] 1. A plurality of conductors having a predetermined pattern are provided, and
an insulating substrate with external connection terminals connected to desired conductors; a piezoelectric element having a plurality of electrodes;
The piezoelectric element is provided with a spacer and a lid having a hole capable of accommodating the piezoelectric element, and the piezoelectric element is disposed on the insulating substrate, and each electrode of the piezoelectric element is connected to a predetermined conductor of the insulating substrate. and the spacer is bonded to the insulating substrate so as to position the positive electric element in the spacer, and the lid body is bonded to the spacer to close the hole. A piezoelectric element component characterized in that the entirety is hermetically covered with an insulating member. 2 In claim 1, as a spacer,
A piezoelectric element component characterized in that it uses an insulating member having a thickness greater than the thickness of the piezoelectric element and having a sticky adhesive attached to at least one surface of the insulating member. 3. The piezoelectric element component according to claim 1, wherein the lid body is formed of a conductive member and is electrically connected to an electrode on the ground side of the piezoelectric element. 4 In claim 1, the insulating member for covering the whole in a sealed state is formed of a first covering layer made of a rubber member and a second covering layer made of a thermosetting resin. A piezoelectric element component characterized by: 5 A piezoelectric element in which a plurality of electrodes in a predetermined pattern are provided on a piezoelectric substrate in a predetermined shape and are directly connected to external connection terminals, and the piezoelectric element is attached to at least one surface of the piezoelectric element, and The piezoelectric element is provided with a spacer having a predetermined thickness and a hole bored in at least a portion corresponding to the working electrode portion, and a lid body attached to the top surface of the spacer so as to close the hole, and the spacer and a piezoelectric element component, characterized in that the entire piezoelectric element including the lid is hermetically covered with an insulating member. 6. The piezoelectric element component according to claim S, wherein the lid body is formed of a conductive member and is electrically connected to an electrode on the ground side of the piezoelectric element. 7 In claim 5, the insulating member for covering the whole in a sealed state is formed of a first covering layer made of a rubber member and a second covering layer made of a thermosetting resin. A piezoelectric element component characterized by: