JPH0152931B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a ceramic filter assembly in which a large number of ceramic filters are held in a divisible manner, and a method for manufacturing the same.

Ceramic filters have been widely used along with LC filters as bandpass filters for intermediate frequency amplification in signal transmission systems such as radios, stereos, televisions, and communications equipment.

By the way, as devices have become more compact, thinner, and more densely packaged, as seen in ultra-thin radios, ultra-compact transceivers, etc., small leadless chip-shaped circuit elements are being used on circuit boards. Assembly of circuit modules by direct soldering between printed patterns is rapidly becoming popular. In order to cope with such technological trends, it is desired that ceramic filters be made into chips as well.

When converting ceramic filters into chips,
Following the example of ceramic capacitors or resistors that have already been made into chips, a piezoelectric ceramic substrate 1 such as barium titanate porcelain or lead zirconate titanate (PbZr) TiO ₃ porcelain is used, as shown in FIGS. Electrodes 2 and 3 are provided on one surface of the electrodes 2 and 3.
Intermediate electrodes 4 are provided with gaps g ₁ and g ₂ between them, and an electrode 5 common to the electrodes 2, 3, and 4 is provided on the other side of the piezoelectric ceramic substrate 1. Take-out electrodes 6 and 7 are electrically connected to the electrodes 2 and 3, respectively, at the side ends of the substrate 1 in the opposite direction (hereinafter referred to as the X direction), and in the direction perpendicular to the X direction (hereinafter referred to as the Y direction). It is conceivable to adopt a structure in which lead-out electrodes 8 electrically connected to the electrodes 5 are respectively adhered to one side surface.

Figure 2 shows an equivalent circuit diagram of the ceramic filter described above, and has a circuit configuration in which three vibrators f ₁ , f ₂ , f ₃ are connected in a T-shape between extraction electrodes 6, 7, and 8. . The number of vibrators f ₁ to _{f 3} can be adjusted to suit the purpose by appropriately selecting the number of electrodes 2 to 5.
Can be set arbitrarily. The aforementioned extraction electrodes 6 and 7 are parts that are fixed to the conductor pattern on the printed circuit board by means such as soldering when the ceramic filter is mounted on a printed circuit board, etc.
It is formed by applying a conductive paste such as Ag or Cu-based paste with a brush onto one end of the electrodes 2 and 3 and then baking it.

However, as shown in FIG. 3, at both ends of the piezoelectric ceramic substrate 1, the surfaces 1a to 1e intersect at right angles, forming right angles _P1 to _P8 .
When applying conductive paste with a brush, the edge angle P ₁ ~
The coating thickness of _P8 tends to be thinner. In order to compensate for this lack of coating thickness, 2 layers were applied to the edge angles P ₁ to P ₈ .
The conductive paste is applied with a brush repeatedly ~3 times, but at this time, the silver paste is also applied around the edge angles P ₁ to _{P 8} , and especially at both ends in the Y direction, the silver paste is applied around the edge angles P ₁ , P ₅ , _P7 , _P2 , _P5 , _P8 , _P3 , _P6 ,
Because P ₈ , P ₄ , P ₆ , and P ₇ intersect three-dimensionally,
As shown in FIG. 4, the thickness of the conductive paste at both ends of the piezoelectric ceramic substrate 1 in the Y direction becomes abnormally thicker than at other ends, and the width _W1 in the Y direction increases.

For this reason, when trying to stack the chip-shaped ceramic filters in a cylindrical magazine of an automatic loading machine one after another, the coating thickness error around the edge angles P ₁ to _{P 8} becomes an obstacle, and the ceramic filters cannot be stored in the cylindrical magazine. There are disadvantages in that it becomes impossible to insert the paper smoothly into the paper, the apparent stacking thickness increases, the amount of insertion by the automatic mounting machine decreases, and the work efficiency of automatic mounting and assembly deteriorates. A similar drawback occurs when a required number of box-shaped magazines are arranged on a lattice-shaped guide plate and a required number of chip-shaped ceramic filters are simultaneously and automatically mounted at predetermined positions on a printed circuit board. Furthermore, the stability is poor when stacked, and troubles are likely to occur during automatic assembly.

In order to solve the above-mentioned problems, a ceramic filter as shown in FIGS. 5A and 5B is effective. In FIGS. 5A and 5B, arc-shaped missing portions 9, 10, 11, and 12 are provided at the four corners of both ends in the X direction of the piezoelectric ceramic substrate 1 formed in the shape of a rectangular flat plate. Extracting electrodes 6 and 7 are formed in the narrow portions 12, respectively.

If such missing portions 9 to 12 are provided, both ends in the Y direction, where the thickness of the conductive paste tends to increase when brush painting, are cut off, and the extraction electrodes 6 and 7 are cut off. Both edges are piezoelectric ceramic substrate 1
Since it is located inside the extension lines L ₁ and L ₂ of the two planes in the Y direction of Never. Therefore, it is possible to very smoothly and reliably insert a predetermined amount into the magazine of the automatic mounting machine, and to perform automatic mounting and assembly operations efficiently.

Furthermore, as shown in Fig. 6, when the ceramic filters are arranged side by side in the Y direction, the lead electrodes 6 and 7 of adjacent ceramic filters are in a non-contact state, so characteristics can be measured in this arrangement. It is also possible to perform operations such as trimming of the electrodes 2 to 5 efficiently.

Note that the missing portions 9 to 12 may have other shapes such as an oblique shape or an angular shape. Moreover, the shape, number, etc. of the electrodes 2 to 5 can also be set arbitrarily.

However, chip-shaped ceramic filters have the same dimensions as chip-shaped ceramic capacitors or resistive elements, which have been developed due to demands for smaller size, larger capacity, and higher density packaging, and because they share the same automatic mounting machine.
The finished dimensions are required to be very small, for example, about 3.2 x 1.6 x 0.6 m/m, and handling as a single unit is troublesome. Furthermore, it is necessary to form an electrode pattern with a complicated shape within a micro area of about 3.2×1.6 m/m. For this reason, it is extremely difficult to handle the ceramic filter as a single unit from the beginning to the end of the manufacturing process.

Therefore, the present invention provides a ceramic filter that is convenient to handle and store, and that does not cause chipping or the like.
It is an object of the present invention to provide a ceramic filter assembly that can be easily determined and a manufacturing method suitable for manufacturing the same.

In order to achieve the above object, a ceramic filter assembly according to the present invention has linear grooves arranged in a lattice pattern on a piezoelectric ceramic substrate formed in the shape of a flat plate, and a filter that is partitioned by the grooves. A ceramic filter assembly in which a ceramic filter element is formed in each region of the shape, and a through hole penetrating in the thickness direction is provided at each intersection of a vertical groove and a horizontal groove constituting the groove, the ceramic filter Each of the elements has a plurality of independent electrodes on at least one side of the region, two of the electrodes being arranged in longitudinal grooves located on either side of the region in a portion narrowed by the through hole. Or, it is characterized by being formed so as to reach above the horizontal groove.

By dividing the ceramic filter assembly constructed as described above along the grooves, individual ceramic filters can be easily taken out. Moreover, when divided, a ceramic filter is obtained which has missing parts due to through holes at the four corners of the opposite side ends of the piezoelectric ceramic substrate formed in the shape of a rectangular flat plate, and the width is narrowed by the missing parts. By attaching a retrieval electrode to the end, it is possible to smoothly and reliably insert a predetermined amount into the magazine of an automatic loading machine, allowing automatic loading and assembly work to be carried out efficiently, and even when lined up. Thus, it is possible to easily obtain a ceramic filter whose characteristics can be efficiently measured and whose electrode trimming operations can be carried out efficiently.

In addition, a through hole is provided at each intersection of the vertical groove and the horizontal groove of the concave groove, which penetrates in the thickness direction.
The horizontal grooves and vertical grooves are discontinuous at the through-holes, allowing accurate division along the grooves without causing damage. Furthermore, since the ceramic filter assembly is many times larger in size than a single ceramic filter, it is convenient to handle and store.

Next, in the method for manufacturing a ceramic filter assembly according to the present invention, grooves are formed in a lattice shape on the surface of an unfired piezoelectric ceramic sheet, and each intersection of the vertical grooves and the horizontal grooves constituting the grooves is A step of drilling a through hole penetrating the piezoelectric ceramic sheet in the thickness direction, a firing step of sintering the piezoelectric ceramic sheet after this step, and a step of forming vertical grooves and horizontal grooves of the recessed groove before or after this firing step. on at least one side of the rectangular area surrounded by the through hole, at least two of which reach above the vertical grooves or lateral grooves located on both sides of the area in the part narrowed by the through hole. , and a step of printing and forming a plurality of independent electrodes.

According to this manufacturing method, the ceramic filter assembly according to the present invention can be easily manufactured with good mass productivity.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The content of the present invention will be specifically explained in detail below with reference to the accompanying drawings which are examples.

FIG. 7 is a plan view of one embodiment of the ceramic filter assembly according to the present invention, and FIG.
FIG. 3 is an enlarged sectional view of the main part along line C ₃ -C ₃ .
In the figure, 13 is a piezoelectric ceramic substrate, which is a sintered body made of barium titanate BaTiO ₃ or lead zirconate titanate (PbZr) TiO ₃ porcelain.

A linear groove is formed on the surface of the piezoelectric ceramic substrate 13.
S ₁ and S ₂ are carved in a grid pattern. One of the grooves S ₁ and S ₂ , for example, the vertical groove S ₁ , is provided with both ends extending to two opposite sides of the piezoelectric ceramic substrate 13 . Moreover, above the vertical groove _S1 and within the regions _Q1 to _Qo divided by the vertical groove _S1 and the horizontal groove _S2 , electrodes 2 to 5 and 8 shown in FIGS. 5A and B are formed. The electrode pattern is Ag,
It is constructed by printing and baking a Cu-based conductive paste. Therefore, a ceramic filter is constructed in each region Q ₁ to _{Q o} .

Further, a through hole 14 passing through the piezoelectric ceramic substrate 13 in the thickness direction is provided at each intersection of the vertical groove S ₁ and the lateral groove S ₂ of the concave groove. The two electrodes 2 and 3 are formed in a portion narrowed by the through hole 14 so as to reach above the vertical groove S ₁ located on both sides of the regions Q ₁ to Q _o . As a result, a connecting portion with an extraction electrode to be provided later is formed.

The piezoelectric ceramic substrate 13 is a hard sintered body, and has concave grooves S ₁ and S _{2 .}
It is easy to break along the However, the concave grooves S ₁ and S ₂
If it is continuous even at the intersection, for example, even if you try to fold it along the vertical groove _S1 , the bending force will also be applied in the direction of the horizontal groove _S2 , and the cutting position will become wedged in the direction of the horizontal groove _S2 at the intersection. It is difficult to fold accurately along the longitudinal groove S ₁ . However, if the through hole 14 as described above is provided, the grooves S ₁ and S ₂ will become discontinuous, and the connection between the ceramic filters at the intersection will be _{severed .} It can be folded and divided accurately along the

In this embodiment, the through hole 14 has a concave groove at the corner.
Although it is shown as a square shape matching S ₁ and S ₂ , it may be circular, oval, or other square shape. Further, although the through holes 14 are expressed as through holes, they may be blocked by conductive paste dripping during the electrode pattern printing process. Further groove
S ₁ and S ₂ may be partially penetrated, or one of them, for example, the groove S ₂ may be provided as a through groove.

Since the ceramic filter assembly according to the present invention has the above-mentioned structure, as shown in FIG.
Apply force F ₁ on both sides of groove S ₁ to form groove S ₁ for each row.
After dividing it along the lines, as shown in Fig. 9a, conductive paste such as Ag or Cu is applied to both sides with a brush to provide extraction electrodes 6 and 7, and then as shown in Fig. 9b. Furthermore, by folding and dividing along the groove S ₂ , the ceramic filter partitioned by the grooves S ₁ and S ₂ can be taken out as a single piece. The ceramic filter taken out in this way is
Similar to FIGS. 5A and 5B, the piezoelectric ceramic substrate 13 has a structure having missing portions at the four corners of opposing end portions.

In this case, the piezoelectric ceramic substrate 13 is a hard sintered body, the grooves S ₁ and S ₂ are mechanically weak, and the through hole 14 is formed at the intersection of the grooves S ₁ and S ₂ . Therefore, each ceramic filter can be easily and accurately divided without causing any chipping or the like.

In addition, by forming the extraction electrodes 6 and 7 at the ends narrowed by the missing parts, they can be smoothly and reliably inserted into the magazine of an automatic loading machine by a predetermined amount. It is possible to obtain ceramic filters that can be assembled efficiently, and whose characteristics can be measured and electrode trimming operations can be performed efficiently when they are lined up. Furthermore, since the shape is many times larger than that of a single ceramic filter, there is no fear of losing it, and it is convenient to handle and store.

Next, a method for manufacturing the ceramic filter assembly described above will be explained. FIGS. 10a to 10c are diagrams explaining the process.

First, as shown in FIG. 10a, a rectangular piezoelectric ceramic substrate 13 is made by punching or the like from a piezoelectric ceramic sheet before firing. This piezoelectric ceramic substrate 13 is
As mentioned above, it is made of barium titanate porcelain, lead zirconate titanate porcelain, or the like.

Next, as shown in FIG. 10b, the piezoelectric ceramic substrate 1
Linear grooves S ₁ and S ₂ are provided in a lattice pattern on the surface of 3, and at the intersection of these grooves S ₁ and S ₂ , the corners are grooved.
A rectangular through-hole 14 corresponding to S ₁ and S ₂ is provided. The grooves S ₁ , S ₂ and the through hole 14 can be formed simultaneously using the same mold or the like.

Next, as shown in FIG. 10c, each area Q ₁ is divided by the top of the vertical groove S ₁ and the vertical groove S ₁ and the horizontal groove S ₂ .
Print and form an electrode pattern within ~ _Qo . When the electrode pattern is formed using Ag or Cu-based conductive paste, the electrode pattern is printed and fixed by baking after baking the piezoelectric ceramic substrate 13. In addition, when the electrode pattern is formed from a metal paste with a high melting point that can withstand the firing temperature, for example, a noble metal paste such as platinum, palladium, or silver-palladium alloy, the electrode pattern is printed on the piezoelectric ceramic substrate 13 before firing. However, the electrode pattern can be baked and fixed at the same time as the piezoelectric ceramic substrate 13 is baked. The electrode pattern is as shown in Figure 7.
At least two of them are formed by printing so as to reach the vertical grooves S ₁ located on both sides of the regions Q ₁ to _{Q o} in the narrow portion made by the through hole 14 .

Through the above steps, the ceramic assembly shown in FIG. 7 is obtained. After this, if necessary, a protective layer such as glass may be coated on the electrode pattern.

FIGS. 11 a ₁ to _{a 5} and FIGS. 11 b ₁ to b ₅ are diagrams illustrating steps in another embodiment of the manufacturing method according to the present invention.

First, as shown in FIG. 11 a ₁ and b ₁ , a strip-shaped piezoelectric ceramic sheet 15 is formed. This piezoelectric ceramic sheet 15 is prepared by preparing a porcelain paste using barium titanate porcelain powder or lead zirconate titanate porcelain powder, an appropriate binder, and an appropriate amount of solvent, and then applying this paste by a doctor blade method, screen process printing method, etc. Obtained by forming into a sheet.

Next, as shown in FIG. 11 a ₂ and b ₂ , holes 16 are bored at both ends of the piezoelectric ceramic sheet 15 in the width W ₂ direction along its length at regular intervals d ₁ . The piezoelectric ceramic sheet 15 is before firing, and the holes 16 can be easily formed using a well-known punching device.

Next, as shown in FIGS. 11 a ₃ and b ₃ , concave grooves composed of vertical grooves S ₁ and lateral grooves S ₂ are provided in a lattice pattern on the surface of the piezoelectric ceramic sheet 15. The formation positions of the grooves S ₁ and S ₂ can be easily determined with the hole 16 as a reference. For example, a sprocket or the like that matches the pitch interval d ₁ of the hole 16 is engaged with the hole 16, the piezoelectric ceramic sheet 15 is fed by the sprocket, and the press mold is driven in synchronization with the rotation of the sprocket. As a result, the grooves S ₁ and S ₂ are provided at predetermined positions with respect to the hole 16.

Next, as shown in FIG. 11, _a4 and _b4 , a through hole 14 is provided at the intersection of the vertical groove _S1 and the horizontal groove _S2 .
The through hole 14 is also formed using a mold or the like, but since the positions of the vertical groove S ₁ , the horizontal groove S ₂ and their intersections can be determined more easily than the hole 16 , the through hole 14 also forms the hole 16 . It can be easily positioned as a reference. Note that the through hole 14 can be formed at the same time as the grooves S ₁ and S ₂ using the same die, and is not limited to an elliptical hole, but may be a circular hole or a square hole.

Next, as shown in FIG. 11 a ₅ and b ₅ , the portions of the piezoelectric ceramic sheet 15 in which the grooves S ₁ and S ₂ have been formed are punched out into, for example, a rectangular shape, and a piezoelectric ceramic substrate for the aforementioned ceramic filter assembly is formed. form 13. This punching step can also be performed simultaneously with the step of forming the grooves S ₁ , S ₂ and the through holes 14 .

Next, through the process explained in FIG. 10c, the electrode pattern, glass layer, etc. are printed, fixed by baking, etc., and the ceramic filter assembly shown in FIG. 7 is obtained.

As described above, the ceramic filter assembly according to the present invention has rectangular regions partitioned by linear grooves provided in a lattice pattern on a piezoelectric ceramic substrate formed in a flat plate shape. a ceramic filter element, and a through hole penetrating in the thickness direction at each intersection of the vertical groove and the horizontal groove of the recessed groove, each of the ceramic filter elements being independent on at least one surface of the area. It has a plurality of electrodes, and two of the electrodes are formed so as to reach above the grooves located on both sides of the region in a portion narrowed by the through hole. From this, the following effects can be obtained.

(a) By dividing along the grooves, it is possible to provide a ceramic filter assembly from which individual ceramic filters can be easily taken out.

(b) When divided, a ceramic filter is obtained that has missing parts due to through holes at the four corners of the opposite ends of the piezoelectric ceramic substrate formed in the shape of a rectangular flat plate, and the missing parts have a narrow width. By attaching a retrieval electrode to the inserted end, it is possible to smoothly and reliably insert a predetermined amount into the magazine of an automatic loading machine, and to perform automatic loading and assembly operations efficiently. Thus, it is possible to easily obtain a ceramic filter whose characteristics can be efficiently measured and whose electrode trimming operations can be carried out efficiently.

(c) Since a through hole is provided at each intersection of the vertical groove and the horizontal groove of the concave groove, the horizontal groove and the vertical groove are discontinuous at the through hole part, and the concave can be formed without causing damage. It is possible to provide a ceramic filter assembly that can be precisely divided along the grooves.

(d) It is possible to provide a ceramic filter assembly that is many times larger in shape than a single ceramic filter and is convenient to handle and store.

Furthermore, in the method for manufacturing a ceramic filter assembly according to the present invention, grooves are formed in a lattice shape on the surface of an unfired piezoelectric ceramic sheet, and the piezoelectric material is applied to each intersection of the vertical grooves and the horizontal grooves constituting the grooves. A step of drilling a through hole penetrating the porcelain sheet in the thickness direction, a firing step of sintering the piezoelectric ceramic sheet after this step, and a step of forming a vertical groove and a horizontal groove of the recessed groove before or after this firing step. on at least one side of the rectangular area surrounded by the through hole, at least two of which reach above the vertical grooves or lateral grooves located on both sides of the area in the part narrowed by the through hole; Since the method includes the step of printing and forming a plurality of independent electrodes, the ceramic filter assembly according to the present invention can be easily manufactured with good mass productivity.

[Brief explanation of drawings]

FIG. 1A is a plan view of a chip-shaped ceramic filter, FIG. 1B is a sectional view taken along line C1 _{- C1} of FIG. 1A, FIG. 2 is an equivalent circuit diagram thereof, and FIGS. 3 and 4. is also a diagram explaining its shortcomings, No. 5
Figure A is a plan view of another chip-shaped ceramic filter, Figure 5B is a sectional view taken along line _C2 - _C2 of Figure 5A, and Figure 6 is a diagram illustrating the effect thereof.
Fig. 7 is a plan view of the ceramic filter assembly according to the present invention, Fig. 8 is an enlarged cross-sectional view of the main part along line C ₃ - C ₃ of Fig. 7, and Figs. 9 a and b similarly explain its handling. Figures 10a to 10c are diagrams illustrating steps in one embodiment of the manufacturing method according to the present invention, and Figures 11 a ₁ to a ₅ are diagrams illustrating steps in another embodiment. Figures b ₁ to _{b 5} are from Figure 11 a ₁
It is each sectional view on the _X1 - _X1 - _X5 - _X5 line of ~ _a5 . 1, 13... Piezoelectric ceramic substrate, 2-5... Electrode, 6-
8... Extraction electrode, 9-12... Missing part, 14... Through hole, 15... Piezoelectric ceramic sheet, _S1 , _S2 ... Concave groove.

Claims (1)

[Scope of Claims] 1 Linear grooves are provided in a lattice pattern on a piezoelectric ceramic substrate formed in a flat plate shape, and a ceramic filter element is formed in each rectangular region partitioned by the grooves. A ceramic filter assembly in which a through hole penetrating in the thickness direction is provided at each intersection of a vertical groove and a horizontal groove constituting the concave groove,
Each of the ceramic filter elements has a plurality of independent electrodes on at least one side of the region, and two of the electrodes are located on both sides of the region in a portion narrowed by the through hole. A ceramic filter assembly characterized in that it is formed so as to reach above vertical or horizontal grooves. 2. Form grooves in a lattice pattern on the surface of an unfired piezoelectric ceramic sheet, and drill through holes that penetrate in the thickness direction of the piezoelectric ceramic sheet at each intersection of the vertical grooves and horizontal grooves that make up the grooves. a firing step of sintering the piezoelectric ceramic sheet after this step;
Before or after this firing step, at least one side of the rectangular area surrounded by the vertical grooves and the horizontal grooves of the groove, and at least two areas of the rectangular area surrounded by the vertical groove and the horizontal groove of the through hole are formed. A method for manufacturing a ceramic filter assembly, comprising the step of printing and forming a plurality of independent electrodes so as to reach above vertical grooves or horizontal grooves located on both sides of the ceramic filter assembly.