JPS5945244B2 - piezoelectric ceramic filter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an energy trap type piezoelectric P-wave device.

Conventionally, a piezoelectric ceramic P-wave device, for example, a piezoelectric element for an FM medium-to-intermediate frequency wave device having predetermined electrodes on both the front and back sides as shown in Fig. 1, has an outer dimension of 3 mm x 3 HUB, and a thickness of 0.208 m.
The piezoelectric element is a thin and minute chip, and the electrodes formed on the piezoelectric element are very close to each other.

Therefore, it is extremely difficult to attach external connection terminals to the electrodes of such piezoelectric elements while maintaining a predetermined electrode spacing, and it is necessary to take extreme care to avoid damage or breakage of the element during assembly. was there.

In FIG. 1, a piezoelectric ceramic P-wave device 100 has an input side terminal electrode 2' and an output side terminal electrode 3' disposed on the main plane of a piezoelectric element substrate 1' with a spacing 5' therebetween. A ground side terminal electrode 4' is disposed on the main plane of.

A piezoelectric ceramic P-wave element ( (hereinafter referred to as a piezoelectric element) is constructed.

Each terminal electrode of the piezoelectric element has an external connection terminal 6.7.
8 is a conductive adhesive (e.g. silver paste) 9.10.1
It is attached by 1.

In such a piezoelectric element, terminal electrodes 2' and 4' or 3' and 4 formed on a piezoelectric element substrate 1 of 3 mm x 3 mm are used.
’ or the interval between 2’ and 3’ is small, less than 3 ho,
It is extremely difficult to apply a conductive adhesive such as silver paste between adjacent terminal electrodes while maintaining a predetermined distance between them, resulting in short circuits and failures due to narrow application intervals of the conductive adhesive.

Further, in a structure in which external connection terminals are attached to a piezoelectric element substrate, the strength becomes weaker when the frequency used becomes higher and the thickness of the piezoelectric element substrate is made thinner.

Furthermore, as the operating frequency increases, the area of the partial electrode required as the vibration excitation electrode becomes extremely small, whereas in a structure where the external connection terminal is taken out from the piezoelectric element substrate, Due to the relationship between the spacing, the area where the conductive adhesive is applied, and the adhesive strength, it is necessary to use a piezoelectric element substrate with a wide area that is more than an order of magnitude larger than the area required for the vibration excitation part, which reduces the cost. It is disadvantageous.

Furthermore, in order to achieve the desired P-wave characteristics, it is necessary to finish the piezoelectric element substrate with high precision, for example, 0.208 mm ± 0.005 mm, and forming the piezoelectric element substrate as small as possible is important for processing efficiency, cost, and product quality. It is desired from the viewpoint of reducing the size.

The present invention provides a piezoelectric ceramic transducer that can solve the above problems.

Hereinafter, the present invention will be explained based on illustrated embodiments.

FIG. 2 is a plan view showing an example of a piezoelectric ceramic filter component used in the present invention.

In the figure, a piezoelectric element (piezoelectric ceramic offshore wave element) 1 is mounted, for example, at opposite corners of one surface of a thin square piezoelectric ceramic plate 50 having a minimum area required for a vibration excitation part and a distance between adjacent electrodes. It is constructed by attaching a terminal electrode 2 serving as an input side, a terminal electrode 3 serving as an output side, and a terminal electrode 4 serving as a grounding side on the other side by means of vapor deposition or the like.

Note that part 2a of the terminal electrode 2 and part 3 of the terminal electrode 3
a are arranged side by side with a gap 5 in the center of the piezoelectric plate 50, and the terminal electrodes 4 are on a diagonal line that is perpendicular to the diagonal line connecting the terminal electrodes 2 and 3, and at least a part of the terminal electrodes and are arranged so as to face each other on the opposite surface of the piezoelectric ceramic 50.

FIG. 3A is a plan view of an example of an insulating substrate used in the present invention, FIG. 3B is a sectional view taken along the line Xl-X1 of FIG. 3A, and FIG. 3C
is a sectional view of another example of an insulating substrate that can be used in the present invention.

In FIG. 3, the insulator substrate 15 is made of phenol, for example.
A printed board made of resin such as polyimide or epoxy and with copper foil adhered to at least one side is etched into a predetermined pattern to form conductive parts 12, 13, 14, or a printed board made of steatite, alumina, etc. Conductive parts 12, 13, as described above are formed on a ceramic or glass substrate.
A conductive film pattern corresponding to 1'4 is formed by plating, vapor deposition, baking, or other means.

Further, the insulator substrate 15 has a conductive portion 12 as described above.
, 13. In addition to 14, an X-shaped (or cross-shaped) slit 16 [see FIG. 3B] or an X-shaped (or cross-shaped) recess 16' [third
(see Figure C) is formed by means such as etching, press working, and ultrasonic processing.

Note that the recess 16' shown in FIG. 3C is processed into a half-blank state using a press machine, and when forming the recess, a protrusion [shown as 15' in FIG. 3C] is formed on the back surface of the insulating substrate 15. ] Needless to say, it is not necessary to form.

By forming the slit 16 (or recess 16') as described above, the part 12 of each conductive part 12, 13° 14
A, 13A, 14A and 14B have sharp tips,
And, their tips are formed into slits 16 (or recesses 16').
) and are electrically insulated from each other.

Then, in each conductive portion 12, 13° 14, a conductive adhesive 17 such as silver paste is applied to a predetermined position near the slit 16 by means such as brush painting or screen printing.

The state is shown in FIG.

Note that FIG. 4B is a sectional view taken along the line X2-X2 of FIG. 4A.

Here, the slit 16 (or recess 16') as described above is used.
) Forming the 17 layers of conductive adhesive in a predetermined pattern on the insulator substrate 15 having a predetermined pattern is easy and efficient regardless of whether it is done by brush painting or printing, and it also reduces the variation in the dimensions of the application position (extremely effective in practice) It is.

The reason for this is that the distance between adjacent conductive parts is determined by the slit 16 (or recess 16'), and the conductive adhesive 1
This is because even if the coating pattern No. 7 deviates from the predetermined position, it is no problem, and there is no risk of unnecessary short-circuiting between adjacent conductive materials or narrowing of the interval between them.

Also, when applying conductive adhesive to machine parts using the screen printing method, the conductive adhesive that adheres to or smudges on the back side of the plate screen may form the sulin H6 (t or recess 16') of the insulating substrate 15. Since it is not transferred to other parts, short-circuits and spacing defects between conductive parts do not occur.

After applying a predetermined pattern of conductive adhesive 17 to the predetermined pattern of conductive portion positions of the insulator substrate 15 as described above, the piezoelectric bare hand 1 shown in FIG. The terminal electrode 2゜3 side of the sensor is placed on the lower side, and each of the terminal electrodes 2 and 3 is connected to a part 12A of the conductive part 12 of the insulator substrate 15 coated with the conductive adhesive 17 and a part 12A of the conductive part 13 of the insulator substrate 15 coated with the conductive adhesive 17. It is placed at the position of the slit 16 (or 16') on the insulating substrate 15 so as to be located above the part 13A.

Note that FIG. 5B is a sectional view taken along the line X3-X3 of FIG. 5A.

Thereafter, by lightly pressing the piezoelectric element 1, each of the terminal electrodes 2 and 3 of the piezoelectric element 1 and the conductive parts 12 and 13 of the insulating substrate 15 are bonded to each other, and at the same time, they become electrically conductive.

Note that the reason why the conductive adhesive 17 is applied not only to the conductive parts 12 and 13 but also to two parts of the conductive part 14 is because the effective adhesive area between the insulator substrate 15 and the piezoelectric element 1 is In addition to ensuring more secure adhesion, when the piezoelectric element 1 is placed on the insulator substrate 15, by attaching it parallel to the insulator, even if the piezoelectric element is pressed, the load can be applied at four equal locations. This is because the conductive adhesive acts as a cushioning material to prevent breakage or damage to the piezoelectric element.

Furthermore, since the slit 16 (or recess 16') is formed at a position facing the resonant electrode portion of the piezoelectric element 1, the conductive adhesive 17 does not touch the insulator substrate 15 even if the piezoelectric element 1 is pressed. It does not spread out between the two and reach the resonant electrode portion.

Furthermore, the conductive adhesive 17 does not smear due to capillary action and does not reduce the distance between adjacent conductive parts or cause a short circuit.

After bonding the piezoelectric element 1 to the insulator substrate 15 as described above, a conductive layer is again attached to the terminal electrode 4 of the piezoelectric element 1 and the first conductive portion 14 of the insulator substrate 15 in order to electrically connect the terminal electrode 4 of the piezoelectric element 1 to the first conductive part 14 of the insulator substrate 15. The adhesive 18 is applied to a predetermined position across the terminal electrode 4 of the piezoelectric element 1 and the conductive portion 14 of the insulating substrate 15 by brush painting or mechanical means.

As a result, all the terminal electrodes 2, 3.4 of the piezoelectric element 1 are electrically connected to the conductive parts 12, 13.14 of the insulating substrate 15.

Thereafter, the conductive adhesive 17 is cured at a predetermined temperature.

If external connection terminals are not attached to the insulating substrate 15 in advance, after these are attached, the piezoelectric element 1 is mounted in a sealed state, thereby completing the assembly of the piezoelectric element parts.

As mentioned above, the slits 16 (or recesses 16') are formed between adjacent conductive parts of the insulating substrate 15, and a conductive adhesive is printed or applied at predetermined positions, and then the area is reduced to the minimum necessary. By mounting the piezoelectric element 1, the mechanical strength of the piezoelectric element is greatly improved and stabilized.
This can prevent breakage or damage to the piezoelectric element, spread or bleed of the conductive adhesive on the lower surface of the piezoelectric element, and can prevent short circuits and poor resonance characteristics from occurring.

Furthermore, the dimensions of the piezoelectric ceramic plate 50 can be reduced, which helps reduce costs.

In addition, since the slit 16 (or recess 16') is equivalent to substantially increasing the distance between adjacent conductive parts several times, it is possible that the conductive adhesive produced by the action of moisture and DC voltage, such as silver paste, It also eliminates serious problems such as silver migration.

Furthermore, it has become possible to automatically apply conductive adhesive by printing or supplying means using micro cylinders, and it has also become possible to reduce variations in the dimensions of the application position, making it possible to automatically assemble piezoelectric elements by machine, etc. This is useful for reducing man-hours and stabilizing quality.

In addition, although the case where the connection of the piezoelectric element with the insulating material board|substrate is carried out by the conductive adhesive was demonstrated by example above, next, the Example in which the connection is carried out by soldering will be described.

However, the drawings are those of FIGS. 4 and 5.

The insulator substrate 15 having a predetermined pattern of conductive parts is produced by etching a printed board with copper foil into a predetermined pattern, or by etching a ceramic or glass substrate into a predetermined pattern, as in the case described above in which the conductive adhesive 17 layer is formed. Formed by methods such as plating, vapor deposition, and baking.

Further, a slit (or recess 16') as described above is formed at a predetermined position where the piezoelectric element 1 is to be placed by an appropriate means.

Further, the surface of the conductive film constituting the conductive portions 12, 13 and 14 in a predetermined pattern is subjected to a treatment such as solder plating or nickel plating to a predetermined thickness.

Then, in the conductive parts 12, 13, 14 which have been subjected to solder plating etc., flux and conductive adhesive 17 are applied to a predetermined position near the slit 16 (or recess 16') as described above. It is applied by brush painting or printing [see Figure 4 A and B].

The flux used has a predetermined viscosity and has the same adhesive effect as an adhesive.

Then, as shown in FIG. 5, place the ground terminal electrode 4 on the upper side and place the flux applied part of the insulating substrate 15 (1 in FIG. 5).
7) and press it lightly.

Note that each terminal electrode 2 of the piezoelectric element 1 used in this example,
3.4 is pre-treated with solder plating to ensure soldering in a short time.

With the piezoelectric element 1 mounted on the insulating substrate 15 via flux, each connection point on the insulating substrate 15 is heated with a hot iron or an infrared lamp, or passed through an atmospheric furnace at a predetermined temperature. The solder applied to the conductive parts 12, 13, 14 and each terminal electrode 2, 3.4 of the piezoelectric element 1 is melted, and the terminal electrode 2 and the conductive part 12, the terminal electrode 3 and the conductive part 13, and the terminal electrode 4 are conductive. The portions 14 are soldered to each other and are electrically connected.

Thereafter, the flux is cleaned, external connection terminals are attached, and the piezoelectric element component is completed through a mounting process.

The slits 16 (or recesses 16') have a remarkable effect in the method of connecting each terminal electrode of a piezoelectric element and each conductive part of an insulating substrate by solder melting as described above.

In other words, the primary purpose of soldering is to prevent solder from forming bridges between each conductive part and/or between each terminal electrode. Promotes dissipation and prevents deterioration of characteristics.

Further, when cleaning the flux used during soldering, the flux adhering to the lower surface of the piezoelectric element can be easily and quickly drained through the slit.

Therefore, no flux remains in the gap between the bonded portion of the insulating substrate and the piezoelectric element, and corrosion and deterioration of resonance characteristics due to the flux can be prevented.

Note that the shape of the slit or recess described in the above embodiments is not limited to the X-shape or cross-shape, but can be made into any shape such as an X-shape depending on the number and arrangement of the conductive parts and terminal electrodes. It goes without saying that it is possible.

Furthermore, the electrical circuit component components to be mounted on the insulating substrate are not limited to the piezoelectric elements mentioned above.
In addition, chip components such as a resistor chip, a capacitor chip, and a semiconductor chip may also be used.

Furthermore, the position and number of the slits or recesses mentioned in the above embodiments can be arbitrarily determined, and the purpose is not only to improve insulation between terminal electrodes provided on a single chip component, but also to provide insulation between multiple chip components. It is also effective when used for

Furthermore, when using a conductive adhesive, the conductive adhesive is not limited to silver paste, but as long as it has conductivity and adhesive properties,
Any material can be used regardless of its type or composition.

As described above, the present invention can be applied even if the piezoelectric ceramic Okinawa wave device component (the piezoelectric element 1 in the embodiment of the present invention mentioned above) is made ultra-miniaturized, or the piezoelectric ceramic P-wave device component is ultra-small. It is also possible to easily derive or connect external connection terminals without short-circuiting the terminal electrodes attached to it or deteriorating its characteristics, and it is also sufficiently strong and low-cost. It has various features such as the ability to obtain a piezoelectric ceramic filter.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an example of a conventional piezoelectric ceramic filter, FIG. 2 is a plan view showing an example of a piezoelectric wave filter component used in the present invention, and FIG. 3 A is a perspective view showing an example of a piezoelectric wave filter used in the present invention. A plan view showing an example of an insulating substrate, FIG. 3B is Xl-X1 in FIG. 3A.
3C is a sectional view showing another example of the insulating substrate used in the present invention, and FIGS. 4 and 5 are diagrams for explaining the assembly process of one embodiment of the present invention. , Figures 4A and 5A are plan views, Figure 4B is x2-x22 of Figure 4A.
5B is a sectional view taken along the line X3-X3 of FIG. 5A. 1... Piezoelectric element, 2, 3, 4... Terminal electrode, 12.13.14... Conductive part, 12A,
13A. 14A...Part of conductive part, 15...Insulator substrate, 16...Slit, 16'...
... Concave portion, 17 ... Conductive adhesive (or flux), 18 ... Conductive adhesive, 50 ...
...Piezoelectric ceramic plate.

Claims (1)

[Claims] 1. A piezoelectric ceramic Oki wave element having a desired shape and size in which a plurality of terminal electrodes are attached in a predetermined pattern on the main plane of a piezoelectric element substrate, and each terminal of the piezoelectric ceramic R-wave element on at least one main plane. The conductive parts to be electrically connected to the electrodes are formed in a predetermined pattern, and the tips of each of the conductive parts are made into a sharp shape on the main plane on which the piezoelectric ceramic Qitowave element is mounted, and the required spacing is maintained. An insulating substrate is provided with an X-shaped or cross-shaped slit or recess for facing and separating, the piezoelectric ceramic R-wave element is laminated and supported on the main plane of the insulating substrate,
A piezoelectric ceramic filter in which each terminal electrode of the piezoelectric ceramic filter element and a corresponding conductive portion of the insulating substrate are electrically connected by a conductive member.