JPH06164206A - Dielectric filter and combination structure of dielectric filter and circuit board - Google Patents

Abstract

PURPOSE:To provide a dielectric filter which can be attached on a surface with reduction of its production cost and the sure acquisition of the Qe capacity and also to provide a combination structure of the dielectric filter and a circuit board. CONSTITUTION:A dielectric block 2 including the counter end faces 3 and 3 and a side circumferential surface 2a is provided together with plural resonator holes 4 which are placed in parallel to each other between both faces 3 of the block 2, an inner conductor 5 formed in each hole 4, an outer conductor 8 formed on the surface 2a, and an electrode film 9 which is formed on both faces 3 and connected to the conductor 8. In such a constitution, a dielectric filter including the input/output electrodes 7 is secured on the surface 2a together with a combination structure of the dielectric filter and a circuit substrate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric filter formed by forming a resonator hole in a dielectric block and a combined structure of the dielectric filter and a circuit board.

[0002]

2. Description of the Related Art Generally, as this type of dielectric filter, for example, a λ / 4 type filter as shown in FIG. 5 is known. The dielectric filter 40 includes a dielectric block 41 made of a dielectric material such as ceramic. In this dielectric block 41, the end surfaces facing each other are a short-circuit side end surface 42 and an open side end surface 43. Two resonator holes 44, which are through holes, are formed in parallel with each other between the both end surfaces 42, 43. An inner conductor 45 is formed on the inner peripheral surface of the resonator hole 44, and an outer conductor 46 is formed on the entire peripheral surface of the dielectric block 41.

An electrode film 47 that short-circuits the inner conductor 45 and the outer conductor 46 is formed on the short-side end surface 42. As a result, a resonant element is formed for each resonator hole 44. Between the resonator holes 44,44, the resonator holes 44,44
Is formed with a coupling hole 48.

In the dielectric filter 40, resin pins 49 are inserted into the resonator holes 44, 44 from the open end face 43 side. The resin pin 49 is for taking a capacity (hereinafter, referred to as Qe capacity) to be coupled with an external circuit.
Further, the metal case 50 is fitted to the dielectric filter 40 from the open end surface 43 side. The metal case 50 is for grounding the dielectric filter 40 and for preventing leakage of electromagnetic field energy.

In the figure, reference numeral 51 is a circuit board to which the dielectric filter 40 is connected via a resin pin 49 and a metal case 50.

[0006]

By the way, in the conventional dielectric filter 40, the resin pin 49 and the metal case 50 must be used. Therefore, there has been a problem that the number of parts increases and the manufacturing cost increases accordingly.

In addition, it is necessary to attach the resin pin 49 and the metal case 50, which are separate parts, to the dielectric block 41, and since the work must be done manually, mass productivity is poor and the manufacturing cost is low. Was rising.

Further, the dielectric filter is characterized in that the higher the resonance frequency, the smaller the Qe capacitance. Therefore, when the above-mentioned conventional dielectric filter 40 is used at a high frequency such as a quasi-microwave band, the Qe capacitance becomes very small, and the axial length of the resin pin 49 used becomes too short, causing the resin pin 49 to resonate. There is a problem in that the work of mounting the resin pin 49 in the cavity hole 44 is more troublesome, the mass productivity is deteriorated, and it becomes difficult to surely mount the resin pin 49 in the cavity hole 44.

Further, in recent electronic parts, it has been required to be surface-mountable in accordance with the demand for higher packaging density, and the same demands have been made in dielectric filters as well. However, in the above-described conventional example, the connection with the external circuit is made via the resin pin 49 and the metal case 50, and it is structurally difficult to mount the surface.

The present invention has been made in view of the above circumstances, and it is possible to reduce the manufacturing cost, obtain a Qe capacitance with certainty, and perform surface mounting, and a dielectric filter and a dielectric. It is intended to provide a combined structure of a filter and a circuit board.

[0011]

In order to achieve the above object, the present invention provides a dielectric block having opposed end faces and side circumferential faces, and is disposed between the end faces in the dielectric block. And a plurality of resonator holes arranged in parallel with each other, an inner conductor formed in the resonator hole, an outer conductor formed on the side peripheral surface of the dielectric block, and formed on both end surfaces and connected to the outer conductor An electrode film is formed on the side peripheral surface, and an input / output electrode is formed on the side peripheral surface.

Further, in order to achieve the above object, the present invention provides a dielectric block having opposing end faces and side circumferential faces, and is disposed between the end faces in the dielectric block and arranged in parallel with each other. Multiple resonator holes, an inner conductor formed in the resonator hole, an outer conductor formed on the side surface of the dielectric block, and an electrode film formed on both end surfaces and connected to the outer conductor. And a circuit board having a line and a ground pattern on the side peripheral surface, and a circuit board having a line and a ground pattern. The conductor and the ground pattern were connected to each other to form a combined structure of the dielectric filter and the circuit board.

[0013]

According to the above construction, an electrostatic capacitance is generated between the input / output electrode and the inner conductor, and this capacitance becomes the Qe capacitance.

Since the outer conductor and the input / output electrodes are formed on the surface of the dielectric block, it is necessary to mount the dielectric block directly on the circuit board for connection with the external circuit provided on the circuit board. Can be done by.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail based on the embodiments shown in the drawings. FIG. 1 is a sectional view of an embodiment of the present invention, and FIG. 2 is a perspective view of the embodiment of the present invention.

This dielectric filter 1 is of the λ / 2 type and comprises a dielectric block 2 made of a dielectric material such as ceramics. Both end faces (upper and lower end faces in the figure) of the dielectric block 2 facing each other are short-side end faces 3, 3
It is said that. Two resonator holes 4 formed of through holes are provided in parallel between the short-side end faces 3 and 3. An inner conductor 5 is formed on the entire inner peripheral surface of the resonator hole 4.

Input / output electrodes 7 and outer conductors 8 are formed on the side peripheral surface 2a of the dielectric block 2. The input / output electrodes 7 are formed on the left and right side peripheral surfaces 2a in FIG. Further, the input / output electrodes 7, 7 are formed at the position where the electric field is strongest on the side peripheral surface 2a, that is, at the center of the axial length of the resonator hole 4 in the λ / 2 type as in the embodiment. Has been done. As a result, the input / output electrodes 7, 7 and the inner conductors 5, 5 are capacitively coupled.

The end portion 7a of the input / output electrode 7 is shown in FIG.
Is formed so as to extend to the side peripheral surface 2a on the back side of the sheet. As shown in FIG. 3, the input / output electrodes 7 and 7 are formed on the mounting surface on the circuit board 20, which will be described later.
You may form on the lower side peripheral surface 2a.

The outer conductor 8 is formed so as to surround the input / output electrodes 7, 7 almost all around the side surface 2a. The outer conductor 8 and the input / output electrodes 7, 7 are electrically connected to each other. It is separated.

An electrode film 9 for short-circuiting the inner conductor 5 and the outer conductor 8 is formed on both short-side end faces 3, 3. And
A coupling hole 10 (coupling means) for coupling the resonance elements is formed between the resonator holes 4, 4. With the above configuration, a total of two resonant elements are configured for each resonator hole 4.

The dielectric filter 1 is surface-mounted on the circuit board 20. That is, the dielectric filter 1 is placed on the circuit board 20 with the peripheral surface 2a on the side where the input / output electrode end 7a is formed facing down. At that time, the input / output electrode ends 7a, 7
The a and the outer conductor 8 are brought into contact with the strip lines 21 and 21 of the circuit board 20 and the ground pattern 22. Then, the strip lines 21, 21 and the input / output electrodes 7,
7 and the outer conductor 8 and the ground pattern 22 are connected by the solder H, and the dielectric filter 1 is fixed to the circuit board 20.

In this dielectric filter 1, a high frequency signal is input / output via the input / output electrodes 7, 7 connected to the strip lines 21, 21. That is, a capacitance S is generated between the input / output electrodes 7, 7 and the inner conductors 6, 6. This capacity S is a so-called Qe capacity. Furthermore, since the Qe capacitance is the capacitance obtained inside the dielectric block 2, the Qe capacitance can be reliably obtained even when the dielectric filter 1 is used at a high frequency such as a quasi-microwave band.

Qe in the dielectric filter 1
The capacitance is adjusted by scraping off the electrode film of the input / output electrodes 7, 7.

Further, since this dielectric filter 1 is of the λ / 2 type, it has no open-side end face and does not leak electromagnetic field energy. Therefore, in addition to the fact that the ground connection can be made by directly connecting the outer conductor 8 to the ground pattern 22 of the circuit board 20, the dielectric filter 1 does not require the metal case 50 as in the conventional case.

Further, in the case of this embodiment, when fixing to the circuit board 20, the input / output electrodes 7 and 7, the outer conductor 8, the strip lines 21 and 21, and the ground pattern 22.
It has a structure in which and are directly connected. Therefore, the connection between them can be made by reflow soldering, which improves the mass productivity.

By the way, in the above-described embodiment, the dielectric filter having two resonator holes 4 was used, but the present invention is not limited to this, and a filter having a plurality of resonator holes 4 in general. Can be carried out. FIG. 4 shows an implementation of the dielectric filter 30 having four resonator holes 4.

In this embodiment, the input / output electrodes 7, 7 are
In the side peripheral surface 2a, the resonator holes 4, 4 of the first and last stages are formed.
And is formed at a position where the electric field is strong. A slit 31 is formed on one of the short-circuit side end faces 3, 3 between the resonator holes 4 ,.
The resonant elements are coupled by. Slit 3
The one may be formed on the other end surface 3 on the short-circuit side, as indicated by an imaginary line.

Further, the slit 31 is structurally capable of forming an electrode film on its inner surface. Therefore, when the slits 31 are used for coupling, the inner conductor 5, the input / output electrode 7, the outer conductor 8, and the electrode films 9 can be plated at one time.
The formation of these electrode films is simplified and mass productivity is improved.

In each of the above-described embodiments, the λ / 2 type dielectric filter is used, but the present invention is not limited to this. For example, a λ type dielectric filter can be used. That is, the present invention can be implemented with a dielectric filter in which electrode films connected to the outer conductor are provided on both end surfaces of the resonator hole 4 at the axial ends. Then, the input / output electrode 7 may be formed on the side peripheral surface 2 a of the dielectric block 2.

[0030]

As described above, according to the present invention, the separate input / output resin pins and metal case are not required. Therefore, the number of parts is reduced and the cost can be reduced accordingly. Further, since it is not necessary to attach another component such as a resin pin or a metal case to the dielectric block, the labor for manufacturing is reduced, mass productivity is improved, and the cost can be reduced by that amount.

Further, even when the dielectric filter is used at a high frequency such as a quasi-microwave band, the Qe capacitance can be easily and surely obtained.

Furthermore, since the dielectric filter can be surface-mounted on the external circuit, the mass productivity can be improved and the high-density mounting can be achieved.

[Brief description of drawings]

FIG. 1 is a sectional view showing the structure of a dielectric filter according to an embodiment of the present invention.

FIG. 2 is a perspective view of an example.

FIG. 3 is a perspective view of an example.

FIG. 4 is a sectional view of an example.

FIG. 5 is a cross-sectional view of a conventional example.

[Explanation of symbols]

 1 Dielectric Filter 2 Dielectric Block 2a Side Surface 3 End Face 4 Resonator Hole 5 Inner Conductor 7 Input / Output Electrode 8 Outer Conductor 9 Electrode Film 20 Circuit Board 21 Stripline 22 Ground Pattern

Claims (2)

[Claims] 1. An end surface (3, 3) and a side peripheral surface (2) facing each other.
a) and a plurality of resonator holes (4) arranged between the end faces (3, 3) in the dielectric block (2) and arranged in parallel with each other. , An inner conductor (5) formed in the resonator hole (4), an outer conductor (8) formed on the side peripheral surface (2a) of the dielectric block (2), and on both end surfaces (3, 3) An electrode film (9) formed on the outer peripheral surface (2) and connected to the outer conductor (8), and an input / output electrode (7) is formed on the side peripheral surface (2a). Body filter. 2. The opposing end faces (3, 3) and the side peripheral face (2)
a) and a plurality of resonator holes (4) arranged between the end faces (3, 3) in the dielectric block (2) and arranged in parallel with each other.
An inner conductor (5) formed in the resonator hole (4), an outer conductor (8) formed on the side peripheral surface (2a) of the dielectric block (2), and both end surfaces (3, 3) A dielectric filter having an electrode film (9) formed thereon and connected to an outer conductor (8), and having an input / output electrode (7) formed on the side peripheral surface (2a); (21) and a circuit board (20) having an earth pattern (22), the input / output electrode (7) is connected to the line (21), and the outer conductor (8) is the earth pattern (22). A combined structure of a dielectric filter and a circuit board, which are connected.