JPH03292005A - Manufacture of dielectric resonator - Google Patents

Abstract

PURPOSE:To manufacture a dielectric resonator whose electrode position accuracy is excellent and whose frequency is made stable and to ensure the economy and high process yield by forming the electrode of a main body made of a dielectric ceramic to one side end face removed through the end face polish by means of printing. CONSTITUTION:Sensitivity processing is implemented on the whole outer surface of a main body made of a dielectric ceramic nearly in the middle of which a throughhole 2 is provided by means of a stannous chloride, then activating processing is implemented by a palladium chloride, a catalyzer metal of electroless copper plating is depositted on the inner circumferential face of the throughhole 2 and on the outer circumferential face of the main body 1, then a metallic film 30 is formed on the entire surface of the main body 1 by the plating process. Moreover, an electroless or electrolytic plating metallic film 20a may be formed on the metallic film 30 as required. After the forming of the metallic film 30a, the metallic film 30 of optional one side face of the main body 1 is polished with high accuracy in parallel by mechanical polish in the end face polish process to expose the main body 1, and an electrode section 40 made of conductive paste is formed on an optional one side face of the exposed main body 1 by screen print or the like and dried or cured.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method of manufacturing a dielectric resonator used, for example, in high frequencies.

BACKGROUND OF THE INVENTION In recent years, with the advancement of information and communication equipment, the demand for high-frequency dielectric resonators used in, for example, car telephones and satellite communications has increased significantly. There is a growing need for improved technology, higher performance, and lower prices.

A conventional dielectric resonator has a typical shape as shown in FIG. 5, where FIG. 5(A) is a perspective view and FIG. 5(B) is a sectional view of FIG. 5(A). Other shapes of dielectric resonators include a rectangular parallelepiped columnar shape, but a cylindrical shape as shown in FIG. 5 is often used because of its excellent spurious characteristics. In Figure 5,
1 is a main body made of dielectric ceramic, 2 is a through hole, and 3 is a metal layer.

This dielectric resonator is made by molding a dielectric ceramic material into an arbitrary size and shape, and sintering it at high temperature.The dielectric resonator is selected by leaving the whole or part of the inner circumferential surface and outer circumferential surface of the through hole 2 of the main body 1. The metal layer 3 is continuously formed with a thickness of about 10 to 20 μm by applying a conductive paste containing a mixture of silver powder and glass frit and firing it at a high temperature of 600 to 800 °C. be. On the other hand, recently, as a metal forming method aimed at lowering the cost and improving the performance of dielectric resonators, metal layer 3 is formed directly on the main body 1 by electroless plating.
There are also methods of forming .

Problems to be Solved by the Invention However, among the dielectric resonators described above, the former, in which the metal layer 3 is formed almost entirely on the main body by a sintered body of silver and glass, uses a noble metal as the electrode material. Therefore, in addition to being expensive, the work of uniformly applying the conductive paste to the outer circumferential surface of the main body 1 and the inner circumferential surface of the through hole 2 is extremely complicated, and there is a problem that mass productivity is lacking.

Therefore, as in the latter method, a method is used in which a copper coating is formed as an electrode layer on the main body 1 by electroless plating (see Japanese Patent Laid-Open No. 108544/1983).

However, in the case of a dielectric resonator in which a metal layer consisting of a plating film is formed on almost the entire surface of the main body 1 using an electroless plating method, and a selective electrode is required on one end face as shown in Fig. 5, the following steps will be taken. There are some issues like this. This problem and a manufacturing method for forming selective electrodes by electroless plating will be explained with reference to the drawings. FIGS. 3 and 4 are cross-sectional views for explaining a conventional method for manufacturing a dielectric resonator.

First, explanation will be given using FIG. 3. As shown in FIG. 3(A), in the catalyst application step, all surfaces of the main body 1 made of dielectric ceramic are sensitized with stannous chloride or the like, and then activated with palladium chloride or the like. Main body 1
Palladium 10, which becomes a catalyst metal, is deposited on the outer peripheral surface of the through hole 2 and the inner peripheral surface of the through hole 2 as a pretreatment for electroless copper plating. Then, after depositing this palladium 10, as shown in Fig. 3 (
As shown in B), in the resist printing process, resist ink 20 is applied to any one end surface of the main body l using screen printing or the like to selectively form an electrode made of a plating film.
Print coating is applied for a distance of about 0 to 2011 m, and then dried or cured.

Then, in the plating process shown in FIG. 3(C), the electrode 30 made of a metal film is formed on the resist ink 20 except for the part above it. To explain in more detail, the electrode 30 is formed by first performing electroless copper plating in the plating process.

As this electroless copper plating, for example, copper sulfate-EDT
Electroless copper plating is performed in a plating bath or the like containing A-formalin-NaOH, and an electrode 30 made of a metal film is deposited on the exposed surface of palladium 10, which serves as a catalyst metal, at a concentration of 0.5 to 1
Shape about 0.0 μm.

Further, if necessary, the electrode 30 may be formed with a metal coating of about 3.0 to 10.0 .mu.m by electroless plating or electrolytic plating on the metal coating made of electroless copper plating. After forming the electrode 30 from the metal film, the resist ink 20 is removed using a solvent or the like in a resist removal step as shown in FIG. 3(D), if necessary.

A manufacturing problem with the above method is that copper from electroless copper plating is deposited on the resist ink 20 during the electroless copper plating process, resulting in poor dimensional accuracy of selective electrodes.

If an electrode with poor dimensional accuracy occurs, the dielectric resonator will have a frequency variation with respect to the desired set frequency, resulting in a manufacturing problem.

Next, another conventional method will be explained using FIG. 4. Fourth
As shown in Figure (A), in the resist printing process, resist ink 2 is applied to any one end surface of the main body 1 made of dielectric ceramic.
0 is applied by printing to a thickness of about 10 to 20 μm using screen printing or the like, and then dried or hardened.

Thereafter, as shown in FIG. 4(B), in the catalyst application step, all surfaces containing the resist ink 20 are sensitized with tinnous chloride or the like on any one end surface of the main body 1 made of dielectric ceramic. and then an activation treatment with palladium chloride or the like.

Furthermore, palladium 1, which becomes a catalyst metal, is applied on the outer circumferential surface of the main body 1 and on the inner circumferential surface of the through hole 2 as a pretreatment for electroless copper plating.
Attach 0. After depositing the palladium 10, the entire surface of the main body 1 including the resist ink 20 on an arbitrary end face is electrolessly plated with the electroless copper plating solution described in the conventional method as shown in FIG. 4(C). The metal film electrode 30 made of copper plating is formed to a thickness of about 0.5 to 1.0 μm.

Next, as shown in FIG. 4(D), in a resist removal process, the resist ink 20 is removed by ultrasonic cleaning using a solvent, and the electrode 3 made of a metal coating of 0.5 to 1.0 μm immediately above the resist ink 20 is removed.
0 can be removed at the same time, making it possible to form selective electrodes. However, since the electrode 30 in this state does not satisfy the electrical characteristics of the dielectric resonator and the reliability determined by general environmental tests, the electrode 30 is made of a metal film made of electroless copper plating on the main body 1. Further, on the electrode 30, a metal coating made of electroless plating or electrolytic plating is applied.
This results in an addition of about 10 to 15 μm.

The manufacturing problem with the above method is that if the electrode 30 made of electroless copper plating with a thickness of 0.5 to 1.0 μm becomes thicker than the desired thickness, the selective It becomes difficult to form the electrode and the dimensional accuracy of the electrode deteriorates, causing the same problems as in the conventional method.

Therefore, the present invention provides a manufacturing method that solves the above-mentioned problems in electrode formation and ensures economic efficiency and high process yield.

Means for Solving the Problems In order to solve the above problems, the present invention provides a plating process for forming a metal plated film on the entire surface of a dielectric ceramic main body that is columnar and has a through hole approximately in the center; an end surface polishing step of removing a metal coating on one end surface of the main body that has been formed with the metal coating; and a printing step of forming an electrode made of conductive paste on the one end surface from which the metal has been removed so as to partially overlap with the metal coating. The method is characterized by the following.

As a result, the metal coating on the main body surface is formed on the entire surface, and the state of electrode formation is determined by printing accuracy.

Therefore, a metal film can be formed using a well-known technique called electroless plating, and selective electrodes can be created using a simple method called screen printing, resulting in a dielectric resonator with excellent cost efficiency, high frequency characteristics, and reliability. will be done.

EXAMPLE Hereinafter, a method of manufacturing a dielectric resonator according to an example of the present invention will be described with reference to the drawings.

1 and 2 are cross-sectional views for explaining a method of manufacturing a dielectric resonator according to a first embodiment of the present invention.

First, the embodiment shown in FIG. 1 will be explained.

In FIG. 1(A), a Ba
All the outer surfaces of the main body 1 made of 0-TiO=based dielectric ceramic are subjected to sensitization treatment with stannous chloride, etc.
Next, activation treatment is performed using palladium chloride or the like, and palladium 10, which becomes a catalyst metal for electroless copper plating, is deposited on the outer peripheral surface of the main body 1 and the inner peripheral surface of the through hole 2. After depositing the palladium 10, a metal coating 30 is formed on the entire surface of the main body 1 in a plating process shown in FIG. 1(B). The method for forming this metal coating 30 will be explained in more detail.

The first step in the plating process is electroless copper plating.

This electroless copper plating is performed in a plating bath containing copper sulfate, EDTA, formalin, and NaOH, and the metal coating 30 is coated on the entire outer surface of the main body 1 with a coating thickness of 5 to 10%.
It forms about μm. Furthermore, if necessary, a metal coating 30a made of electroless plating or electrolytic plating may be further formed on the metal coating 30 made of electroless copper plating to a thickness of about 5 to IQlim. After forming the metal coating 30a made of electroless plating or electrolytic plating, in the edge polishing step shown in FIG. The end face is polished with high precision to expose the main body 1.

An electrode portion 40 made of a conductive paste is formed by screen printing or the like on any one end face of the main body 1 exposed by this end face polishing, and is dried or hardened.

Next, the embodiment shown in FIG. 2 will be explained. Palladium 1 is deposited on the entire surface of the dielectric ceramic body 1 in FIG. 2(A).
The steps from the step of applying a metal catalyst of 0 to the step of forming the electrode part 40 made of the conductive paste as shown in FIG. 2(D) by screen printing or the like and drying or curing are the same as in the embodiment shown in FIG. The major difference between the embodiment shown in Fig. 2 is that Fig. 2 (E
), and after drying or curing, an electrode part 40 made of conductive paste is further formed on the metal coating 30 made of electroless copper plating and the electrode part 40 made of conductive paste. A metal coating 30a made of electrolytic copper plating or electrolytic plating is formed to a thickness of about 3 to 1011 m.

The dielectric resonator according to the embodiment described above is manufactured by forming a metal film on the surface of the main body 1 by a simple method using a series of wet plating, and then using a conductive paste by a common method called screen printing. Since the electrodes are formed on the polished surface of one end face, there are no problems caused by the conventional methods that have been used up until now. As a result, mass processing becomes possible, resulting in a significant reduction in man-hours and an improvement in process yield.

Effects of the Invention In the present invention, the electrodes of the main body made of dielectric ceramic are printed on one end face removed by end face polishing, so the positioning accuracy of the electrodes is good and a dielectric resonator with a stable frequency can be created. Since it is a simple method, it is possible to provide a dielectric resonator that is easy to manufacture, can be mass-produced, and has stable frequency characteristics.

A cross-sectional view for explaining the method of manufacturing a body resonator, FIG.
A) and (B) are a perspective view and a sectional view showing a typical conventional dielectric resonator.

1... Body, 2... Through hole, 30, 30a
...Metal coating, 40... Electrode part.

Claims (1)

[Claims] A plating process for forming a metal coating on the entire surface of a dielectric ceramic body that is columnar and has a through hole approximately in the center, and edge polishing for removing the metal coating from one end surface of the body on which the metal coating is formed. and a printing step of forming an electrode made of conductive paste on one end surface from which the metal coating has been removed so as to partially overlap the metal coating.