JPS63306701A - Dielectric filter - Google Patents

Abstract

PURPOSE:To simplify the input/output structure and to mount the dielectric filter onto the face of a circuit board by using one of the faces with a wide area in the outer surface where the resonator hole of the dielectric block is not opened as a mount face onto a printed circuit board and placing the face laterally. CONSTITUTION:One face 22 having a wider area among the outer surfaces where the resonator hole 14 of the dielectric block 12 is not opened is used as a mount face to a printed circuit board 24, an input/output terminal pattern 26a is formed on the block 12 so as to be reach the mount face 22 and a non conductor layer part 28 is formed therearound so as to separate the vicinity of the pattern 26a of the mount face 22 from a conductor layer 20. The conductor layer is provided up to a prescribed depth in the inside of the input/output hole 18 located at both ends and the pattern 26a is formed so as to be in continuity therewith. The dielectric filter 10 of the said structure is placed laterally on the board 24 and fixed. Then the pattern 26a and the strip line 30 of the board 24 are soldered. Thus, the height of the filter 10 mounted on the board 24 is very low and no terminals are projected and the space factor is also reduced.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a dielectric filter with an integral structure used in high frequency bands such as microwaves, and more specifically, the present invention relates to a dielectric filter with an integral structure used in high frequency bands such as microwaves. The present invention relates to a dielectric filter that is formed of a thick film or the like and can be surface-mounted directly on a circuit board like a chip component.

[Prior Art] Multi-stage resonator filters using dielectric ceramics such as barium titanate are conventionally known, and have characteristics such as low loss, so-called high Q, and high dielectric constant, allowing for miniaturization. It is already widely used in the field of microwave mobile radio technology such as car telephones.

As a conventional technique regarding a dielectric filter, a plurality of resonator holes and coupler holes are provided alternately at a predetermined interval in the longitudinal direction of a rectangular parallelepiped dielectric block, and the resonator holes of the dielectric block are There is an integrated multi-stage structure in which a large number of resonant elements are formed by forming a metallized layer on the outer surface other than the open surface and the inner surface of the resonator hole, with one of the open surfaces being open.

In such a dielectric filter, each resonator hole corresponds to a single resonant element, and the height of the dielectric block is approximately determined by its dielectric constant and resonant frequency.

There are several coupling structures for such a dielectric filter and an external circuit.For example, there is a structure in which a coupling capacitor is attached to the open end of a resonator hole located at both ends and the coupling capacitor is connected to the external circuit.In general, a penetrating structure is used. The glass terminal is attached to the case, and the dielectric block is housed inside the case.

In another structure, holes are formed at both ends of the dielectric block, input/output pin terminals are inserted into the holes, and metal earthing fittings are attached to the grounding surface.

[Problem that the invention seeks to solve]

However, conventional dielectric filters have a problem in that the overall size of the filter increases due to the input/output terminal structure.

In other words, the method using a coupling capacitor requires a metal case, which inevitably increases the size of the entire filter.In addition, the structure in which the input/output pin terminal is inserted into the hole and the grounding fitting is attached around it increases the length of the hole. The dimensions will become larger.

However, with recent advances in surface mount technology,
This type of dielectric filter is also required to be handled on the same level as a chip capacitor, but the conventional techniques described above cannot meet this requirement.

An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art, simplify the input/output coupling structure, and provide a low-profile dielectric filter that can be surface-mounted on a circuit board. be.

[Means for Solving the Problems] The present invention provides a plurality of resonator holes in the longitudinal direction of a dielectric block having a substantially rectangular parallelepiped shape, and one surface of the dielectric block where the resonator holes are open. The present invention is based on a dielectric filter having an integral structure in which a conductor layer is formed on the other outer surface and the inner surface of the resonator hole, with the surface being an open surface.

In order to achieve the above-mentioned object, in the present invention, one of the larger surfaces of the outer surface where the resonator hole is not opened is used as the mounting surface for the circuit board, and the resonator is directly inserted onto the dielectric block. The output terminal pattern is formed so as to reach the mounting surface, and a non-conductor layer portion is provided around the periphery to separate the vicinity of the input/output terminal pattern on the mounting surface from the conductor layer.

There are several structures for the input/output terminal pattern formed here. For example, holes for input/output coupling are formed at both ends of the dielectric block, and the other end is connected to the conductor layer on the inner surface, and the other end is placed on the 11Il placement surface side. There is a structure in which an input/output terminal pattern is provided on an open surface extending all the way through the dielectric block, and a structure in which an island-shaped input/output terminal pattern is formed on the side of a dielectric block. Alternatively, an input/output terminal pattern may be provided so as to be continuous with the resonator holes located at both ends, and a coupling capacitor may be provided on the circuit board side.

[Function] With this structure, the dielectric filter is placed horizontally with respect to the circuit board, so its height can be made as small as possible. Further, since there is no part protruding from the dielectric block as an input/output terminal part, the width dimension can be reduced.

Since input/output terminal patterns are formed directly on the dielectric block, connections can be completed simply by soldering along the strip lines on the circuit board, and automatic assembly using a component mounting machine is also possible. becomes.

Furthermore, since there is no part protruding from the dielectric block as an input/output terminal, the size of that part can also be reduced.

[Example] FIG. 1 is a perspective view showing an example of a dielectric filter according to the present invention, and FIG. 2 is an explanatory view showing a state in which it is attached to a circuit board.

The basic structure of the dielectric filter can be considered to be almost the same as that of the conventional technology.The dielectric filter IO is composed of a rectangular parallelepiped-shaped dielectric block 12 made of a sintered body of a high dielectric constant ceramic material such as barium titanate. Three resonator holes 14 are formed at predetermined intervals in the longitudinal direction, and a coupler hole 16 is provided between the resonator holes 14, and input/output holes 18 are further formed at both ends. One of the surfaces of the dielectric block 12 where the resonator hole 14 is open is an open surface, and a metallized layer 20 is formed on the other outer surface and the inner surface of the resonator hole 14, forming an integral structure.

In the drawings, in order to more clearly represent the metallized parts, the parts where the dielectric base is exposed without being metallized are shown with fine dots. The metallized layer 20 is a thin layer formed by baking a silver paste or the like.

Now, as is clear from FIGS. 1 and 2, the present invention is significantly different from the prior art in that one of the surfaces with a larger area among the outer surfaces where the resonator hole 14 is not opened (in this case, The surface indicated by the symbol "22" is the mounting surface for the circuit board 24, and the input/output terminal pattern 26m is placed on the dielectric block 12.
is formed so as to reach the mounting surface 22, and the mounting surface 2
The vicinity of the input/output terminal pattern in step 2 is separated from the conductor layer 20 (this is because a non-conductor layer portion 28 is formed around it).

Here, a conductor layer is provided to a predetermined depth inside the input/output holes 18 located at both ends, and the input/output terminal pattern 26a is formed to be continuous with the conductor layer 2 on the circuit board 2.
4, a strip line 30 is formed in advance at a position corresponding to the input/output terminal pattern 26a.

The dielectric filter 10 having such a structure is placed horizontally and adhesively fixed on the circuit board 24, as shown in FIG.

Then, the input/output terminal pattern 26a formed on the dielectric block 12 and the strip line 3 formed on the circuit board 24
Connect with 0 by soldering. Since the non-conductor layer portion 28 is provided around the connection portion as described above, there is no possibility that problems such as solder flowing and reaching the metallized layer 20 during heating will occur.

As a result, the dielectric filter 1 mounted on the circuit board 24
The height of 0 is very low, and the input/output terminals do not protrude, so the space factor is small, which is extremely convenient.

Input/output terminal pattern 26 formed on dielectric block 12
The shape of a may be a pattern shape that slightly extends into the mounting surface 22 in order to further ensure soldering.

FIG. 3 is an explanatory diagram showing another embodiment of the present invention. In this embodiment, input/output terminal patterns 26b are provided so as to reach the storage surface so as to be electrically connected to the inside of the resonator holes 14 located at both ends.

In the case of such a structure, for example, if the strip line 30 of the circuit board 24 is partially separated and a chip capacitor 32 for coupling is attached to that part as shown in the figure, the connection can be made through the strip line 30. can be used to perform the binding.

Such structures are also useful.

FIG. 4 is an explanatory diagram showing still another embodiment of the present invention.

In this embodiment, an island-shaped input/output terminal pattern 26C is provided on the side surface facing the resonator hole 14, and coupling is performed between this pattern and the resonator hole 14 located at the end. . In such a case, the pattern can be similarly extended to reach the mounting surface, and the non-conductor layer portion 28 can be formed to separate the vicinity of the input/output terminal pattern on the mounting surface from the conductor layer. , it can be easily and reliably connected to the strip line 30 of the circuit board 24.

Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to such a configuration. The structure may be such that a pattern is provided, and the number of resonator holes to be formed is not limited to the side stages, but can also be applied to two or four or more.

[Effects of the Invention] As described above, the present invention has a configuration in which the dielectric block is placed horizontally with one of the larger surfaces of the outer surface where the resonator holes are not opened as the mounting surface for the circuit board. Therefore, it is possible to reduce the height of the dielectric filter relative to the circuit board. In addition, since the input/output terminal pattern is formed directly on the dielectric block, there is no protruding part for the terminal.
In that respect as well, it is possible to achieve miniaturization and space saving.

As a result, in the present invention, the m8 body filter can be surface-mounted, and automatic assembly can be performed using a component mounting machine or the like.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing one embodiment of a dielectric filter according to the present invention, FIG. 2 is an explanatory diagram showing an example of its mounting state, and FIG. 3 is an explanatory diagram showing another embodiment of the present invention. FIG. 4 is an explanatory diagram showing still another embodiment of the present invention. 10... Dielectric filter, 12... Dielectric block, 14... Resonator hole, 18... Input/output hole, 20...
...Metallized layer, 22... Placement surface, 24... Circuit board, 26a, 26b, 26c... Input/output terminal pattern, 28... Non-conductor layer portion, 30... Strip line. Patent Applicant Fuji Electrochemical Co., Ltd. Agent Shigeru Mi 4 Figure 1 Figure 2 Figure 3 Yodo Figure 4

Claims (1)

[Claims] 1. A plurality of resonator holes are provided in the longitudinal direction of a dielectric block having a substantially rectangular parallelepiped shape, and one of the surfaces of the dielectric block where the resonator holes are open is an open surface, and the other outer surface and the above-mentioned resonance are formed. In a dielectric filter having an integral structure in which a conductor layer is formed on the inner surface of the resonator hole, one of the larger surfaces of the outer surface where the resonator hole is not opened is used as a mounting surface for the circuit board, and the dielectric filter An input/output terminal pattern is formed directly on the block so as to reach a mounting surface, and a non-conductive layer portion is provided around the block to separate the vicinity of the input/output terminal pattern on the mounting surface from the conductive layer. A dielectric filter featuring: