JPH0832310A - Dielectric filter and manufacture therefor - Google Patents

Abstract

PURPOSE:To eliminate the need of positioning with a dielectric block for a printing pattern and to accurately stipulate a formation area for an external conductor film and a conductor film pattern by forming the conductor film pattern on the flat upper surface of a projecting part on the surface of the dielectric block. CONSTITUTION:Through-holes 2A, 2B and 2C parallel to four side surfaces are parallelly formed in a prismatic ceramic dielectric block 1 and the open end surface 11 is provided with the conductor film patterns 4A, 4B and 4C. They are in the same shape and formed on the projecting part 15 provided with the flat upper surface one degree higher than the periphery. That is, the projecting part 15 is constituted of the projecting parts 14A, 14B and 14C and also, the conductor film patterns 6A and 6B for input/output terminals are provided while being positioned at recessed parts 16A and 16B on a terminal surface 13 which is one of the four side surfaces of the block 1. The patterns 6A and 6B are in the same shape and they are formed in the projecting parts 17A and 17B provided with the flat upper surface one step higher. Since the contraction of dimensions occurs in calcination after the formation of the block 1, it is taken into consideration at the time of design and silver paste is printed there.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric filter used for mobile or portable communication equipment such as car telephones and mobile telephones, and radio communication equipment in the microwave band such as satellite broadcasting and a method of manufacturing the same. Regarding

[0002]

2. Description of the Related Art In recent years, mobile or portable communication devices such as car phones and mobile phones, and wireless communication in the microwave band such as satellite broadcasting have become popular. Is becoming more rapid. These communication devices include a band pass filter (BP) because of their features such as small size and light weight, low loss, and small temperature coefficient.
Dielectric filters are widely used as F).

As such a dielectric filter, for example, one having a structure shown in Japanese Patent Publication No. 3-69202 is known, and this kind of dielectric filter has one or a plurality of penetrating holes in a ceramic dielectric block. A structure in which a hole is provided, a conductor film is provided on an inner surface of the through hole and an outer surface of the ceramic dielectric block parallel to the axial direction of the through hole, and a conductor film is also provided on an end surface where one of the through holes is opened. Has become.

FIG. 4 shows a prismatic ceramic dielectric block 21 used in a conventional dielectric filter. In this prismatic ceramic dielectric block 21, three through holes 22A, 22B and 22C are arranged at equal intervals. Has been formed. The prismatic ceramic dielectric block 21 has six flat surfaces except for the through holes.

5 and 6 show a conventional example of a dielectric filter 20 using the prismatic ceramic dielectric block 21. The dielectric filter 20 shown in these figures
Is manufactured by the following procedure. First, a conductor paste is applied to the four side surfaces (the outer surface parallel to the axial direction of the through hole) and the short-circuited end surface (the surface where one of the through holes is open) of the prismatic ceramic dielectric block 21 by screen printing or the like as thick film printing. (Silver paste or the like) is printed to form a thick film of the conductor paste to be the outer conductor film 27.

Further, a conductor film pattern 24A connected to the thick film of each through hole 22A, 22B, 22C is formed on the open end surface (upper surface) 31 of the ceramic dielectric block 21 in which the other of each through hole 22A, 22B, 22C is opened. , 24B, 24C
A thick film pattern of a predetermined shape to be formed is formed by printing a conductor paste by screen printing or the like, and an earth side conductor film pattern 25 surrounding the thick film pattern to be connected to the central through hole 22B is formed. The side thick film pattern is formed by similar screen printing or the like.

Further, each through hole 22A, 22B, 22C
One of the outer surfaces (side surfaces) 32 of the ceramic dielectric block 21 parallel to the axial direction of is the terminal surface 33, and the terminal surface 3
3, the input / output terminal thick film pattern to be the input / output terminal conductive film patterns 26A, 26B connected to the thick film pattern provided around the through holes 22A, 22C of the open end surface 31 is screened on the terminal surface 33. It is formed of a conductor paste when printing or the like.

Before and after the thick film printing, a metal rod or the like to which a conductor paste is attached is inserted into the through holes 22A, 22B and 22C of the prismatic ceramic dielectric block 21 and rotated, and the like. Inner conductor films 23A, 2A, in which a conductor paste is applied to the inner surfaces of the through holes 22A, 22B, 22C and connected to the thick film pattern of the short-circuited end face and the thick film pattern of the open end face.
A thick film of conductor paste to be 3B and 23C is formed.

By printing and baking the applied conductor paste thick film, the through holes 22A, 22A,
The inner conductor films 23A, 23B, 2 are formed on the inner surfaces of 22B, 22C.
3C is formed, and the inner conductor film 23 is formed on the open end face 31.
Conductor film patterns 24A, 24B and 24C of a predetermined shape connected to A, 23B and 23C and a ground side conductor film pattern 25 are formed. Input / output terminal conductor film patterns 26A, 26B connected to the conductor film patterns 24A, 24C are formed on the terminal surface 33. Further, the four side surfaces of the ceramic dielectric block 21 and the through holes 22A, 2
An outer conductor film 27 connected to the inner conductor films 23A, 23B, 23C and the ground side conductor film pattern 25 is formed on the short-circuited end surface (bottom surface) where one of 2B and 22C is opened.

In this case, for example, a three-stage band pass filter can be constructed, and the input / output terminal conductor film patterns 26A, 26 are provided.
B can be used to connect to an antenna or amplification means, and the filter characteristics can be improved or adjusted depending on the shapes of the conductor film patterns 24A, 24B, and 24C on the open end face 31.

[0011]

By the way, like the dielectric filter 20 illustrated in FIG. 5, the inner conductor films 23A, 23B and 23C are used to improve or adjust the filter characteristics.
Specific shape conductive film patterns 24A, 24B,
24C and conductor film pattern 2 for input / output terminals coupled to this
When it is necessary to form 6A, 26B and the like on a plurality of surfaces of the ceramic dielectric block 21, the conductor paste is attached to each surface of the ceramic dielectric block 21 by screen printing as thick film printing as described above. ing.

However, when the conductive paste is printed by screen printing or the like as thick film printing, if the alignment of the printing plate and the dielectric block 21 is insufficient, the through holes 22A, 22B, 22C and The positional relationship with the conductor film patterns 24A, 24B, and 24C due to the film printing is deviated. Therefore, due to the structure of the dielectric filter, there is a problem that the characteristics of the filter largely vary depending on the positional relationship between the through holes 22A, 22B, 22C of the dielectric block 21 and the conductor film patterns 24A, 24B, 24C to be printed. is there. In particular, miniaturization of the dielectric filter is required along with miniaturization of mobile or portable communication equipment, and the through hole 22A is reduced due to miniaturization and miniaturization of the conductor film pattern accompanying miniaturization of the ceramic dielectric block. , 22B, 22C and the conductor film patterns 24A, 24B, 24C, the influence of the printing accuracy is further increasing.

In view of the above points, the first object of the present invention is to
An object of the present invention is to provide a dielectric filter which has a small variation in filter characteristics and is suitable for miniaturization.

A second object of the present invention is to provide a method of manufacturing a dielectric filter which can form a conductor film having high pattern accuracy on a dielectric block.

Other objects and novel features of the present invention will be clarified in Examples described later.

[0016]

In order to achieve the above object, the dielectric filter of the present invention has an inner conductor film formed on the inner surface of the through hole of the dielectric block and is parallel to the axial direction of the through hole. An outer conductor film connected to the short-circuited end of the inner conductor film is formed on the short-circuited end face of the dielectric block where one of the through-hole and the outer surface of the dielectric block is open, and the other of the through-holes is opened. In the case of forming a conductor film pattern connected to the open end of the inner conductor film in a region including at least the open end face of the dielectric block, the region where the conductor film pattern is formed on the surface of the dielectric block. Is formed by the flat upper surface of the convex portion, and the conductor film pattern is provided over the entire area of the flat upper surface.

Further, in the method for manufacturing a dielectric filter of the present invention, the inner conductor film formed on the inner surface of the through hole of the dielectric block, the outer surface of the dielectric block parallel to the axial direction of the through hole, and the outer surface of the dielectric block. An outer conductor film formed to be connected to the short-circuited end of the inner conductor film on the short-circuited end face of the dielectric block having one of the through-holes opened, and the dielectric film having the other of the through-holes opened. In the case of manufacturing a dielectric filter including a conductor film pattern formed on a surface including at least an open end surface of a body block, a region of the surface of the dielectric block where the conductor film pattern is formed is a flat upper surface of a convex portion. After forming the dielectric block as described above, the conductor film pattern is formed on the entire area of the flat upper surface.

The conductor film pattern can be formed by printing a conductive material over the entire area of the flat upper surface and baking it.

[0019]

In the dielectric filter and the method of manufacturing the same of the present invention, the area for forming the conductor film pattern to be connected to the inner conductor film on the inner surface of the through hole of the dielectric block is formed as a convex portion on the surface of the dielectric block. The conductor film pattern may be provided over the entire area of the flat upper surface that is one step higher than the circumference of the convex portion. At this time, the positional relationship between the convex portion and the through hole can be made constant by simultaneously processing the through hole and the convex portion at the time of molding the dielectric block. It is possible to prevent the fluctuation of the filter characteristics due to the positional deviation.

The conductor film pattern can be easily formed by printing a conductive material (conductor paste) on the entire flat upper surface of the convex portion and baking it. in this case,
Since the flat upper surface is one step higher than the surroundings, the printing plate can be a full-scale printing pattern or a pattern slightly larger than the flat upper surface, and the influence of misalignment between the printing plate and the dielectric block. Can be ignored.

Therefore, it is possible to easily form a highly accurate conductor film pattern, and it is possible to sufficiently cope with miniaturization and miniaturization of the conductor film pattern accompanying miniaturization of the dielectric filter.

Further, since there is a recess between each conductor film pattern and the outer conductor film, there is no dielectric. Therefore, crosstalk or coupling between the conductor film patterns can be prevented, which is also effective for miniaturization and higher frequencies.

[0023]

Embodiments of the dielectric filter and the manufacturing method thereof according to the present invention will be described below with reference to the drawings.

An embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a completed dielectric filter, and FIG. 2 shows a prismatic ceramic dielectric block used in the embodiment.

First, the prismatic ceramic dielectric block 1 shown in FIG. 2 is manufactured. The prismatic ceramic dielectric block 1 has through holes 2A, 2B and 2C parallel to four side surfaces, and is the same as the conductor film patterns 4A, 4B and 4C of FIG. 1 to be formed on the open end surface 11. A convex portion 14A having a flat upper surface (upper end surface) which is higher than the surroundings,
14B and 14C, the convex portion 1 having the same shape as the ground-side conductor film pattern 5 and a flat upper surface one step higher than the surroundings.
5 is formed. In addition, the input / output terminal conductor film pattern 6 is formed on the terminal surface 13 on one of the four side surfaces of the dielectric block 1.
Recesses 16A and 16B surrounding the regions where A and 6B are provided are formed. As a result, the input / output terminal conductor film pattern 6 is formed.
The convex portions 17A and 17B having the same shape as A and 6B and a flat upper surface higher than the surroundings are formed. These through holes 2A, 2B, 2C, convex portions 14A, 1
4B, 14C, 15, 17A, 17B and recess 16A,
16B is formed at the same time as the prismatic ceramic dielectric block 1 is manufactured by molding a ceramic material with a mold and firing it. The height of each convex portion is preferably in the range of 0.1 mm to 1 mm. If the thickness is less than 0.1 mm, the difference in the unevenness is small, and the conductive paste may adhere to the recesses during thick film printing. If the thickness is greater than 1 mm, the characteristics of the unevenness are affected, which is not suitable for downsizing.

The prismatic ceramic dielectric block 1
The shrinkage of dimensions caused by firing after molding of the
It is taken into consideration in advance when designing the patterns of A, 14B, 14C, 15, 17A, and 17B. That is, the area of the flat upper surface of each convex portion before firing is formed to be slightly larger in consideration of the shrinkage ratio during firing.

Next, the prismatic ceramic dielectric block 1
A conductor paste (silver paste or the like) as a conductive material is printed on each outer surface by screen printing or the like as thick film printing. The printing pattern here may be, for example, in the case of screen printing, the printing plate (printing screen) may be an entire surface printing pattern. By printing the conductor paste using the printing plate of the entire surface printing pattern, the conductor paste is formed only on the entire flat upper surface (upper end surface) of the convex portions 14A, 14B, 14C, 15 on the open end surface 11 of the prismatic ceramic dielectric block 1. 1 and 3, a thick film pattern to be the conductor film patterns 4A, 4B, 4C respectively connected to the thick film on the inner surface of each of the through holes 2A, 2B, 2C is formed as shown in FIGS. A thick film pattern to be the side conductor film pattern 5 is formed. Further, on the terminal surface 13 of the dielectric block 1, the recesses 16A, 16B are formed.
The thick film to be the input / output terminal conductor film patterns 6A and 6B connected to the conductor film patterns 4A and 4C by depositing the conductor paste on the regions except the regions, that is, the entire flat upper surfaces of the protrusions 17A and 17B and the remaining protrusion regions. And the outer conductor film 7 around it
A thick film to be formed is formed. Further, on the remaining outer surface 12 (three side surfaces) of the dielectric block 1 and the short-circuit end surface (bottom surface) 18 shown in FIG. 3, the conductor paste is adhered over the entire surface, and the short-circuit end surface 18 forms the inner surface of the through holes 2A, 2B, 2C. A thick film is formed which is to be the outer conductor film 7 connected to the thick film and connected to the thick film as the ground-side conductor film pattern 5 on the open end face 11. The thick films to be the outer conductor film 7 on each outer surface are continuously connected.

Before and after the printing and application of the conductor paste on the outer surfaces, a metal rod or the like to which the conductor paste (silver paste or the like) is attached is inserted into the through holes 2A, 2B and 2C and rotated. Then, a conductor paste is applied to the inner surface of each through hole 2A, 2B, 2C to form a thick film to become inner conductor films 3A, 3B, 3C.

Then, by baking the conductor paste printed on each surface including the inner surfaces of the through holes 2A, 2B, 2C, the inner conductor films 3A, 3B, 2B, 2C are formed on the inner surfaces of the through holes 2A, 2B, 2C. 3C is formed, and the conductor film pattern 4 connected to the inner conductor films 3A, 3B, 3C is formed on the open end surface 11.
A, 4B, 4C and the ground side conductor film pattern 5 are formed, and the terminal face 13 is formed with input / output terminal conductor film patterns 6A, 6B connected to the conductor film patterns 4A, 4C. Outer surface 12 and short-circuited end surface 1
An outer conductor film 7 connected to the short-circuited ends of the inner conductor films 3A, 3B, and 3C and the ground-side conductor film pattern 5 is formed at 8. From the above, the dielectric filter 10 shown in FIG. 1 is obtained.

In the case of the above dielectric filter 10, for example, 3
A band-pass filter of a step can be configured, the input / output terminal conductor film patterns 6A and 6B can be used to connect to an antenna or an amplification means, and the conductor film patterns 4A and 4 of the open end face 11 can be formed.
Filter characteristics can be improved or adjusted by the shapes of B and 4C.

According to this embodiment, the following effects can be obtained.

(1) Convex portions 14A, 14B, 14C having the same shape as the conductor film patterns 4A, 4B, 4C and the ground-side conductor film pattern 5 and having a flat upper surface which is one step higher than the surroundings, 15 and recesses 16A, 1
Protrusions 17A and 17B surrounded by 6B and having a flat upper surface having the same shape as that of the input / output conductor film patterns 6A and 6B.
Through holes 2A in the prismatic ceramic dielectric block 1
It is preformed at the same time as 2B and 2C, and a conductor paste (silver paste or the like) is formed on the open end surface 11 and the terminal surface 13.
Since the conductor paste is attached only to the entire flat upper surface (upper end surface) of the convex portion of the outer surface with unevenness by screen printing etc.
The formation regions of the conductor film patterns 4A, 4B and 4C, the ground side conductor film pattern 5 and the input / output terminal conductor film patterns 6A and 6B can be accurately defined. That is, the conductor films 4A, 4B, 4C, 5, 6A, 6B and the through holes 2A,
The positional relationship with 2B and 2C becomes constant. In particular, since there is no fear that the positional relationship between the through holes 2A, 2B, 2C and the conductor film patterns 4A, 4B, 4C, which has been a problem in the related art, will not occur, the filter characteristics of the dielectric filter 10 are stabilized.

(2) Through holes 2A, 2B, 2C and convex portion 14
A, 14B, 14C, 15, 17A, 17B and recess 1
6A and 16B are conductor pastes that are formed at the same time when the prismatic ceramic dielectric block 1 is formed and have a constant size, and that are used to form the conductor films 4A, 4B, 4C, 5, 6A, 6B and 7. Since no alignment is required in printing, it is possible to easily form a highly accurate conductor film pattern, and it is possible to sufficiently cope with miniaturization and miniaturization of the conductor film pattern accompanying miniaturization of the dielectric filter. .

(3) Each conductor film pattern 4A, 4B, 4
Since C, 5, 6A and 6B are formed on the flat upper surface of the convex portion of the prismatic ceramic dielectric block 1 excluding the concave portion, there is a concave portion between the conductor film patterns and no dielectric substance exists. Therefore, crosstalk between patterns and coupling can be prevented. Further, it is effective for miniaturization and high frequency.

(4) When the dielectric filter 10 is mounted on a printed circuit board and the conductor lands on the printed circuit board are connected to the input / output terminal conductive film patterns 6A and 6B by soldering, the input / output terminal conductive film is used. Since the recesses 16A and 16B are formed around the patterns 6A and 6B, there is no possibility that a short circuit will occur with the outer conductor film 7. Also, the flux cleaning can be performed well.

In the above embodiment, the printing plate for screen-printing the conductor paste is formed by the whole surface printing pattern. However, the open end surface 1 of the dielectric block 1 is formed.
1 and the terminal surface 13, the conductor film patterns 4A, 4
The screen printing may be performed using a printing plate having a printing pattern that is slightly larger than the pattern shapes of B, 4C, the ground side conductor film pattern 5 and the input / output terminal conductor film patterns 6A, 6B. In this case, even if the positional relationship between the printed pattern and the through holes 2A, 2B, 2C is slightly deviated, the conductive paste adheres on the open end surface 11 and the terminal surface 13 to the respective convex portions 14A, 14B, 14C, 15
Of the conductor film patterns 4A, 4B, 4C, 5 and 6 only on the entire flat upper surface of the terminal surface 13 and on the flat upper surface of the convex portions 17A and 17B excluding the concave portions 16A and 16B of the terminal surface 13 and the remaining outer surface.
The positional relationship between A and 6B and the through holes 2A, 2B and 2C can be accurately defined, and the shape does not change (area does not change).

As the thick film printing means, screen printing or transfer of a conductive paste using a rubber roller can be used.

Although the embodiment of the present invention has been described above, it is obvious to those skilled in the art that the present invention is not limited to this and various modifications and changes can be made within the scope of the claims. Let's do it.

[0039]

As described above, according to the dielectric filter and the method of manufacturing the same of the present invention, the inner conductor film is formed on the inner surface of the through hole of the dielectric block having the through hole, and the axis of the through hole is formed. An outer conductor film that is connected to the short-circuited end of the inner conductor film is formed on the short-circuited end face of the dielectric block in which one of the through-hole and the outer surface of the dielectric block parallel to the direction is opened, and the through-hole is formed. In the case of forming a conductor film pattern connected to the open end of the inner conductor film in a region including at least the open end face of the dielectric block having the other open, the conductor film pattern on the surface of the dielectric block The region where is formed is the flat upper surface of the convex portion, and the conductor film pattern is formed over the entire flat upper surface of the convex portion, and the alignment between the printed pattern and the dielectric block is unnecessary, Before It has the advantage that the formation area of the conductor film pattern and the outer conductor film can be accurately defined, and there is no risk of the positional relationship between the through-hole and the conductor film pattern, which has been a problem in the past, occurring. Is stable.

Further, it is possible to easily form a highly accurate conductor film pattern, and it is possible to sufficiently cope with miniaturization and miniaturization of the conductor film pattern accompanying miniaturization of the dielectric filter.

Furthermore, since each conductor film pattern and the outer conductor film are concave, and there is no dielectric, crosstalk between patterns and coupling can be prevented, which is effective for miniaturization and high frequency operation. Is.

Therefore, a compact and highly reliable dielectric filter having stable filter characteristics can be realized.

[Brief description of drawings]

FIG. 1 is a perspective view showing a dielectric filter after a conductor film is formed (completed state) in an embodiment of a dielectric filter and a method for manufacturing the same according to the present invention.

FIG. 2 is a perspective view showing a dielectric block used in an example.

FIG. 3 is a partial cross-sectional view showing the periphery of a through hole of a dielectric filter after formation of a conductor film.

FIG. 4 is a perspective view showing a dielectric block before formation of a conductor film in a conventional dielectric filter.

FIG. 5 is a perspective view showing a conventional dielectric filter after formation of a conductor film.

FIG. 6 is a partial cross-sectional view showing the periphery of a through hole of a conventional dielectric filter after formation of a conductor film.

[Explanation of symbols]

 1 prismatic ceramic dielectric block 2A, 2B, 2C through hole 3A, 3B, 3C inner conductor film 4A, 4B, 4C conductor film pattern 5 earth side conductor film pattern 6A, 6B input / output terminal conductor film pattern 7 outer conductor film 10 Dielectric Filter 11 Open End Face 12 Outer Surface 13 Terminal Surface 14A, 14B, 14C, 15, 17A, 17B Convex Part 16A, 16B Recessed Part 18 Short-Circuited End Face

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Junichi Sudo 1-13-1 Nihonbashi, Chuo-ku, Tokyo TDK Corporation

Claims (3)

[Claims] 1. A dielectric body, wherein an inner conductor film is formed on an inner surface of a through hole of a dielectric block, and an outer surface of the dielectric block parallel to an axial direction of the through hole and one of the through holes are opened. An outer conductor film is formed on the short-circuited end face of the block to connect to the short-circuited end of the inner conductor film, and the inner conductor film is formed in a region including at least the open end face of the dielectric block in which the other of the through holes is open. In a dielectric filter for forming a conductor film pattern connected to the open end of, the region of the surface of the dielectric block where the conductor film pattern is formed is composed of a flat upper surface of a convex portion, and the entire area of the flat upper surface is formed. A dielectric filter comprising the conductor film pattern. 2. An inner conductor film formed on an inner surface of a through hole of a dielectric block, and an outer surface of the dielectric block parallel to an axial direction of the through hole and one of the dielectric holes having the through hole opened. An outer conductor film formed on the short-circuited end surface of the body block so as to be connected to the short-circuited end of the inner conductor film, and a surface including at least the open end surface of the dielectric block in which the other of the through holes is open. In the method of manufacturing a dielectric filter including a conductor film pattern, the dielectric block is formed so that a region of the surface of the dielectric block where the conductor film pattern is formed is a flat upper surface of a convex portion. A method of manufacturing a dielectric filter, characterized in that the conductor film pattern is formed over the entire flat upper surface. 3. The method for manufacturing a dielectric filter according to claim 2, wherein the conductive film pattern is formed by printing a conductive material on the entire area of the flat upper surface and baking it.