JP2007028139A - Manufacturing method of dielectric resonator and filter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dielectric filter that obtains a high Q being the special feature of a coaxial type, attains downsizing and a low height by a lamination structure, and includes characteristics of a low loss and a high attenuation amount. <P>SOLUTION: The manufacturing method of the dielectric filter wherein two or more through-holes are formed in a dielectric ceramic includes: laminating and sticking ceramic dielectric green sheets with pressure; forming a plurality of holes penetrated through the laminated sheets at a prescribed interval; cutting off the laminated sheets in a way of including at least two through-holes and dividing them into a plurality of division elements; baking the elements; and forming an inner conductor in the through-holes and forming an outer conductor, a short-circuit conductor and a terminal electrode on the surface of each element. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a coaxial dielectric resonator and a filter manufacturing method, and more particularly, to a method of configuring a dielectric resonator and a filter combining them by a multilayer chip filter manufacturing method.

  A coaxial block type dielectric filter has a plurality of parallel through holes formed in a dielectric block, an inner conductor on the surface of the through hole, an outer conductor on the surface of the block, and a short-circuit conductor on one of the end faces. . Since this type of dielectric filter requires a molding process, a groove process, and a bonding process, it is difficult to reduce the size and height of the dielectric filter. So far, the height dimension limit is 1.2mm, making it difficult to meet specifications such as 1.0mmMAX and 0.6mmMAX, which are the mainstream of recent requirements. In addition, it is difficult to form a high-aspect-ratio dielectric block and a narrow hole to form the center (inner) conductor. Conductor film formation in the thin hole is performed by plating or paste injection. It becomes difficult as becomes smaller.

There is a laminated LC filter composed of lumped constants, but the inductance part and strip line part have a ribbon-like structure, so that the electric field concentrates on the edge. For this reason, the Q is smaller than that of a block type dielectric filter having a coaxial electrode structure, and it is inevitable that the characteristics of the filter are lowered.
JP 2003-60406 A JP 2003-8304 A

  The present invention provides a dielectric filter having a high Q which is a feature of the coaxial type, realizing a small size and a low profile by a laminated structure, and having a low loss and a high attenuation characteristic.

  This invention solves said subject by utilizing a sheet | seat lamination method. That is, in a method for manufacturing a dielectric filter having two or more through holes in a dielectric ceramic, the ceramic dielectric green sheets are laminated and pressure-bonded, and a plurality of holes penetrating the laminated sheets are arranged at a predetermined interval. The sheet formed so as to include at least two through holes is cut and divided into a plurality of elements, the elements are baked, the inner conductor is formed in the through hole, and the outer conductor is formed on the surface of the element. The short-circuit conductor and the terminal electrode are formed.

  According to the present invention, by adopting a laminated structure in the dielectric coaxial filter, a columnar electrode with a fine pore can be formed, so that a high aspect ratio dielectric block can be obtained. As a result, it is possible to reduce the height of the monoblock type dielectric filter. The previous limit of 1.2 mm could be reduced to 0.6 mm.

The process of the present invention is shown in the following order.
(1) Lamination of ceramic dielectric green sheets (2) Formation of through holes in the laminate (3) Division into chips (4) Firing (5) Electrode application and baking (5) Electrode application in (5) ( It is also possible to perform baking and baking at the same time after the division into 3) chips. Alternatively, holes may be formed in the ceramic dielectric green sheet in advance, the layers may be stacked while being aligned, and then the through holes may be processed with high accuracy.

  Embodiments of the present invention will be described below with reference to the drawings. The example shown in FIG. 1 is for producing a two-element interdigital dielectric filter. A ceramic dielectric green sheet is laminated to a predetermined thickness. The thickness is back-calculated from the resonance frequency of the dielectric filter determined by the dielectric constant of the ceramic dielectric and the contracted length after firing, and a predetermined number of sheets are stacked and bonded together. Holes may be formed in the sheet in advance by laser processing or the like. In that case, the holes are stacked while being aligned by inserting the holes into a guide. (Figure 1a)

  A through-hole is formed by perforating a dielectric in which sheets are laminated and pre-press-bonded at a predetermined interval in the lamination direction (that is, a direction perpendicular to the sheet surface). This process is performed by a high-speed drill, a punch, or the like. When holes are formed in the sheet in advance as described above, it is preferable to form holes slightly wider than the diameter of the holes, and the time for forming holes can be shortened. Maintenance is also easy. (Fig. 1b)

  Here, a conductor film that finally becomes the inner conductor of the dielectric filter can be formed on the surface of the through hole. This conductor film may be formed after firing the dielectric block. However, since the conductor film can be formed in a large number of through holes before division, it is advantageous in terms of manufacturing man-hours. Thereafter, the device is cut to obtain a dielectric block chip. (Fig. 1c, Fig. 1d)

  Although firing is performed in the state of this chip, a conductor film may be formed at predetermined positions on the surface and end face of the dielectric block before firing. A terminal electrode in which a conductor film formed on the surface serves as an outer conductor, a conductor film formed on a part of the end surface serves as a short-circuit conductor, and a conductor film that separates a part of the outer conductor and faces the inner conductor obtains a coupling capacity It becomes. The conductor film is baked simultaneously with the firing of the ceramic dielectric, and the dielectric filter shown in FIG. 2 is obtained.

  In the present invention, it is necessary to perforate the ceramic dielectric in the form of a green sheet, but the order of forming the conductor film can be arbitrarily changed. In addition, a plating process may be added to increase the reliability of the conductor film and maintain a high Q.

  A device having the size shown in FIG. That is, this is a two-element filter in which a through hole having a diameter of 0.2 mm is formed in a dielectric block having a length of 2.8 mm, a width of 1.6 mm, and a height of 0.6 mm to form an electrode similar to that shown in FIG. The characteristics are shown in FIG. The center frequency was 5.874 GHz, the bandwidth that attenuated 0.8 dB from the peak was 250 MHz, and the insertion loss from 5.8 to 5.85 GHz was 2.2 dB. Since the resonator Q can be made higher than that of a lumped constant type multilayer filter having the same volume, sharp attenuation characteristics can be obtained.

  Although the above example has a two-element interdigital structure, a comb line may be used, and the number of elements may be any number of three or more. Of course, it can be used for a duplexer or a band rejection filter, and a single element can be a resonator or a trap.

  The present invention is suitable for manufacturing filters in fields where there is a strong demand for small size, thinness, and light weight, such as filters for terminals of mobile communication devices.

The perspective view which shows the Example of this invention The perspective view of the dielectric filter obtained by this invention The perspective view of the dielectric filter obtained by this invention Explanatory drawing of characteristics of dielectric filter obtained by the present invention

Explanation of symbols

11: Ceramic dielectric green sheet
13: Through hole
15: Input / output electrode (terminal)
17: Earth electrode (outer conductor, short-circuit conductor)

Claims (6)

In a method of manufacturing a dielectric filter having two or more through holes in a dielectric ceramic,
Laminate ceramic dielectric green sheets and crimp them.
Forming a plurality of holes penetrating the laminated sheets at a predetermined interval;
The sheet laminated so as to include at least two through-holes is cut and divided into a plurality of elements,
Firing those elements,
An inner conductor is formed in the through hole, and an outer conductor, a short-circuit conductor, and a terminal electrode are formed on the surface of the element. In a method for manufacturing a dielectric resonator having a through hole in a dielectric ceramic,
Laminate ceramic dielectric green sheets and crimp them.
Forming a plurality of holes penetrating the laminated sheets at a predetermined interval;
The sheet laminated to include at least one of those through holes is cut and divided into a plurality of elements,
Firing those elements,
An inner conductor is formed in a through-hole, and an outer conductor, a short-circuit conductor, and a terminal electrode are formed on the surface of the element.   3. The manufacturing method according to claim 1, wherein at least the inner conductor is baked simultaneously with the baking of the element. In a method of manufacturing a dielectric filter having two or more through holes in a dielectric ceramic,
A plurality of through holes are formed in a predetermined arrangement in the ceramic dielectric green sheet,
Laminate the ceramic dielectric green sheets with the holes aligned, and press
The sheet laminated so as to include at least two through-holes is cut and divided into a plurality of elements,
Firing those elements,
An inner conductor is formed in the through hole, and an outer conductor, a short-circuit conductor, and a terminal electrode are formed on the surface of the element. In a method for manufacturing a dielectric resonator having a through hole in a dielectric ceramic,
A plurality of through holes are formed in a predetermined arrangement in the ceramic dielectric green sheet,
Laminate the ceramic dielectric green sheets with the holes aligned, and press
The sheet laminated to include at least one of those through holes is cut and divided into a plurality of elements,
Firing those elements,
An inner conductor is formed in a through-hole, and an outer conductor, a short-circuit conductor, and a terminal electrode are formed on the surface of the element.   6. The method according to claim 4, wherein the through holes are formed by forming holes after laminating the sheets.

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