JPH06196901A - Dielectric resonator - Google Patents

Abstract

PURPOSE:To suppress the adverse effect of soldering at a low cost by constituting an electrode film of a copper plating layer formed on the surface of a dielectric substance, a nickel plating layer formed on the copper plating layer and a silver plating layer formed on the nickel plating layer. CONSTITUTION:Each dielectric resonator consists of a dielectric block 9 like a rectangular parallelopiped, a through hole is formed on the center part of the block 9, an outer conductor 13 is stuck to the block 9 and the conductor 13 is short-circuited with an inner conductor on the rear end face of the block 9. The conductor 13 consists of a copper plating layer 101 formed on the surface of the block 9 a nickel plating layer 102 formed on the layer 101 and a silver plating layer 103 formed on the layer 102. In the case of fixing the dielectric resonator in a case e.g. by soldering, the infiltration of the solder is interrupted by the layer 102. Consequently the adverse effect of the solder is not easily exerted upon the external conductor (electrode film) 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric resonator,
In particular, the present invention relates to a dielectric resonator formed by forming an electrode film on the surface of a dielectric.

[0002]

2. Description of the Related Art A dielectric resonator is formed by depositing electrode films on the outer surface of a dielectric block having a through hole and the inner surface of the through hole. Such a dielectric resonator is
A single unit is used for a voltage controlled oscillator (VCO) or the like, and a combination of a plurality is used for a filter or the like. A dielectric resonator used as a dielectric filter is integrally fixed to an electrode film of a circuit board, a metal case, or the like via solder.

As the main material of the electrode film of the dielectric resonator, copper plating, which has excellent electrical characteristics and is highly workable, is often used. A general electrode film is formed by stacking a copper plating layer and a silver plating layer. The copper plating layer includes an electroless copper plating layer (2 to 3 μm) and an electrolytic copper plating layer (2
0 to 30 μm). The silver plating layer is formed by electrolytic plating to a thickness of 5 to 10 μm.

[0004]

In the conventional dielectric resonator described above, when assembled as a dielectric filter, the solder erodes the electrode film in a high temperature environment such as in a reflow furnace.
When the material is eroded, the electrode film becomes partially thin, and the electrical characteristics (Q value) of the filter deteriorate. Further, when tin of the solder diffuses into the electrode film and reaches the interface between the dielectric block and the electrode film, the adhesion strength between the two decreases. As a result, the electrode film is easily peeled off when a shock or the like is applied. The peeling of the electrode film changes the filter characteristics and reduces the reliability of the product.

In order to prevent the above-mentioned unfavorable results,
A method of increasing the thickness of the electrolytic plating layer among the copper plating layers can be considered. However, since it takes a long time to thicken the copper plating layer, the workability is poor, and the copper consumption is large and the cost is high. An object of the present invention is to suppress the adverse effect of solder on a dielectric resonator at low cost.

[0006]

A dielectric resonator according to the present invention comprises a dielectric and an electrode film deposited on the surface of the dielectric. The electrode film is composed of a copper plating layer formed on the surface of the dielectric, a nickel plating layer formed on the copper plating layer, and a silver plating layer formed on the nickel plating layer.

It is preferable that the copper plating layer has a thickness of 5 to 10 μm, the nickel plating layer has a thickness of 1 to 3 μm, and the silver plating layer has a thickness of 1 to 3 μm.

[0008]

In the dielectric resonator according to the present invention, the nickel plating layer is formed between the copper plating layer and the silver plating layer of the electrode film. When the dielectric resonator is fixed to a case with solder, for example, the penetration of solder is blocked by the nickel plating layer. Therefore, the solder is unlikely to adversely affect the electrode film. Therefore, it is not necessary to increase the thickness of the copper plating layer, the workability and the material used are improved, and the manufacturing cost can be reduced.

[0009]

1 to 3 show a dielectric filter 1 in which dielectric resonators 7 and 8 are employed as an embodiment of the present invention. This dielectric filter 1 includes a filter body 2 in which a pair of dielectric resonators 7 and 8 are arranged in parallel, an upper case 3 and a lower case 4 that house the filter body 2, and dielectric resonators 7 and 8. A pair of capacitors 17 and 18 arranged on the open end face side of the
It is composed of a pair of connection terminals 5 and 6.

The filter body 2 is formed by adjoining two independent dielectric resonators 7 and 8 in an electromagnetically coupled state. Each of the dielectric resonators 7 and 8 is mainly composed of a rectangular parallelepiped dielectric block 9, and a through hole 10 extending in the longitudinal direction is formed at the center thereof. Through hole 10
A cavity 11 is provided at the front end of the open end face side opening. A capacitor 17 is housed in this cavity 11.

An inner conductor (electrode film) 12 is deposited on the inner peripheral surface of the through hole 10 and the surface of the cavity 11. An outer conductor (electrode film) 13 is attached to the outer peripheral surface of the dielectric block except for the open end surface on the cavity 11 side. The outer conductor 13 is formed on the rear end surface of the dielectric block 9 by the inner conductor 1.
Shorted to 2. The outer conductor 13 is, as shown in FIG.
Copper plating layer 101 formed on the surface of the dielectric block 9
And a nickel plating layer 102 formed on the copper plating layer 101 and a silver plating layer 103 formed on the nickel plating layer 102. Copper plating layer 101
Is formed by an electroless plating method and has a thickness of 5 to
It is 10 μm. The nickel plating layer 102 is formed by an electroless plating method and has a thickness of 1 to 3 μm.
The silver plating layer is formed by electrolytic plating and has a thickness of 1 to 3 μm. The inner conductor 12 also has a similar three-layer structure.

As shown in FIG. 3, an angular hole 16 extending in a direction orthogonal to the through hole 10 is formed at the junction between the dielectric resonators 7 and 8, and the electromagnetic field coupling is provided by the hole 16. The state is formed. Input / output capacitors 17, 18
Is composed of a disk-shaped dielectric body 20, and inner electrodes 21 and outer electrodes 22 arranged on both surfaces of the dielectric body 20. The inner electrodes 21 of the input / output capacitors 17 and 18 are connected to the inner conductor 12 in the cavity 11. On the outer electrodes 22 of the capacitors 17, 18, the lead terminals 5,
6 is attached.

The lead terminals 5 and 6 have a lead portion 23 protruding to the outside and a joint portion 2 formed at the other end of the lead portion 23.
4 and an extension portion 25. At the center of the joint portion 24, a hole 24a for injecting cream solder and a cut-and-raised piece 24b are formed. The extending portions 25 are on the same plane as the joint portion 24 and extend from the joint portion 24 toward the sides closer to each other. An air gap 27 for forming a predetermined electrostatic capacitance is formed between the extending portions 25, and serves as a static capacitance for polarization.

The upper case 3 and the lower case 4 are mainly composed of a substantially rectangular metal plate 30 and a metal plate 40 on which the filter body 2 is placed. This metal plate 30, 40
Elastic guides 31 and 41 are integrally provided at both side edge portions of the. In the vicinity of the elastic guide 31, ground terminals 32 that project horizontally from the metal plate 30 are integrally formed. In addition, a third ground terminal 34 is integrally provided at the center of the front side of the metal plate 30 so as to project in the horizontal direction from the metal plate 30. Further, a lower connection piece 35 protruding from the metal plate 30 so as to straddle the ground terminal 34.
Are provided integrally. The lower connecting piece 35 is a metal plate 40.
The upper connecting piece 42 is engaged to fix both cases 3 and 4.

Next, a method of manufacturing the dielectric filter 1 will be described. First, the inner conductor 12 and the outer conductor 13 are formed on the prepared dielectric block 9. Here, first, an electroless plating method is applied to form a copper plating layer 101 on the surface of the dielectric block 9 with a thickness of 5 to 10 μm. Then, the copper plating layer 10 is formed by electroless plating.
The nickel-plated layer 102 is formed in a shape of 1 to 3 μm in thickness. Finally, the silver plating layer 103 is formed on the nickel plating layer 102 to a thickness of 1 to 3 μm by the electrolytic plating method. In this state, heat treatment at 200 ° C. or higher is performed to reduce the resistance value of the inner conductor 12 and the outer conductor 13 and improve the adhesion strength. Each plating layer is also formed on the open end surface, which is removed by polishing.

Further, as shown in FIG. 3, cream solder 100 is applied on the metal plate 30 of the lower case 3, and the filter body 2 is placed on the lower case 3 using the elastic guide 31. Next, the inner electrodes 21 of the capacitors 17 and 18 and the inner conductor 12 inside the cavity 11 are temporarily fixed with cream solder, the outer terminals 22 are brought into contact with the lead terminals 5 and 6, and the upper electrodes are temporarily fixed with cream solder. . Since the lead terminals 5 and 6 are integrally connected by a lead frame formed by punching and bending a metal plate plane, an air gap 27 having a predetermined width is formed at the tip of the lead terminals 5 and 6. Are pre-formed.

Next, the upper case 3 is put on the filter body 2 via the cream solder 100. Upper case 3
Is fixed to the filter body 2 and the lower case 4 by the elastic guide 41 and the upper connecting piece 42. Then, cream solder is applied to the joint surfaces of the upper and lower connecting pieces 35, 42. The dielectric filter 1 in which the upper and lower cases 3 and 4 are assembled is passed through a reflow furnace, and the temporarily fixed joints are soldered. As a result, joining of all joints is completed by one soldering process.

Next, the lead terminals 5 and 6 joined to the outer electrode 22 are cut to separate the lead terminals 5 and 6 into independent terminals. An air gap 27 having a predetermined width is formed at the tip of the extending portion 25 of the lead terminals 5 and 6, and a predetermined amount of capacitance is obtained between the terminals by the air gap 27. During the manufacturing process, when soldering each joint through a reflow furnace, the solder erodes the outer conductor 13. However, the silver plating layer 103 is corroded by the solder, but since the corrosion by the solder is blocked by the nickel plating layer 102, the electrical characteristics of the filter 1 are maintained. Moreover, since the diffusion of tin in the solder is blocked by the nickel plating layer 102, the adhesion strength between the dielectric block 9 and the outer conductor 13 is maintained strong.

As a result, it is not necessary to make the outer conductor 13 thick, so that the material cost and the working time can be reduced. Here, the electroless nickel plating layer 102 is used.
Is set to a thickness of 1 μm or more, which is sufficient to block corrosion by solder. Moreover, although nickel has a low resistivity, its layer is formed as thin as 3 μm or less, so that the electrical characteristics of the filter 1 can be maintained. The copper plating layer 101 is set to 10 μm or less, which is significantly thinner than the conventional copper plating layer.
Therefore, the plating process time and the material are reduced, and the manufacturing cost is reduced.

[0020]

In the dielectric resonator according to the present invention, the penetration of solder is blocked by the nickel plating layer, so that the electrode film is less likely to be adversely affected by solder. Therefore, it is not necessary to increase the thickness of the copper plating layer, the workability and the material used are improved, and the manufacturing cost can be reduced.

[Brief description of drawings]

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

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is an exploded perspective view of the dielectric filter.

FIG. 4 is a cross-sectional view of an outer conductor (electrode film).

[Explanation of symbols]

 7, 8 Dielectric resonator 9 Dielectric block 13 Outer conductor 101 Copper plating layer 102 Nickel plating layer 103 Silver plating layer

Claims (1)

[Claims] 1. A dielectric resonator comprising a dielectric and an electrode film deposited on the surface of the dielectric, wherein the electrode film comprises a copper plating layer formed on the surface of the dielectric. A dielectric resonator comprising a nickel plating layer formed on the copper plating layer and a silver plating layer formed on the nickel plating layer.