JPH05110321A - Electrode forming method for microwave use dielectric resonator - Google Patents

Abstract

PURPOSE:To avoid swell due to plating and to attain excellence in the economy by forming a chemical plating Ni-P being a background electrode as a specific film and applying thick plating by means of chemical Cu plating. CONSTITUTION:The surface of a dielectric resonator ceramics 2 is processed in the order of degreasing, chemical etching, susceptibility and activation, a film 4 is formed for a background electrode whose thickness is 0.1mum or over and less than 1/10 of the skin depth by the chemical Ni-P plating, and thick plating is implemented as a layer 5 by chemical Cu plating to form double electrode layers. After the chemical etching processing is implemented in this way, when the chemical Ni-P plating 4 is implemented as the background plating, since the Ni-P in the etching trace is grown from the initial deposition in a minute film form, the close adhesion on the border of the dielectric substance raw Ni-P film is very excellent. The swell due to plating is avoided by forming the Cu film on the Ni-P film face by the chemical Cu plating.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming electrodes of a dielectric resonator used for high frequencies and the like.

[0002]

2. Description of the Related Art A sectional view of a dielectric resonator is shown in FIG. As a method of forming electrodes on this dielectric resonator, a conductive paste in which Ag fine powder and glass frit are mixed has been conventionally applied selectively while leaving all or part of the inner peripheral surface and the outer peripheral surface. There is a method of forming an electrode layer by baking at a high temperature of 900 ° C. On the other hand, in recent years, a method of directly forming electroless Cu plating on the main body has been performed as an electrode forming method aiming at cost reduction and high performance of the dielectric resonator.

[0003]

Among the conventional electrode forming methods, the former one in which an electrode layer is formed of a sintered body of Ag and glass is expensive because the electrode material used is a noble metal. Of course, the work of uniformly applying the conductor paste to the inner and outer peripheral surfaces of the dielectric is extremely complicated and lacks mass productivity. Further, in order to improve the adhesion strength and the solder wettability, since metal such as Pt and Pd is contained, there is a problem that the electric resistance, which has a great influence on Q, which is an important characteristic of the dielectric resonator, becomes large. Therefore, as in the latter method, a method of forming a Cu film as an electrode layer by electroless Cu plating on a dielectric is performed. However, electroless Cu
When the Cu film formed by the plating method is used as the electrode layer, so-called plating blisters frequently occur especially on the inner peripheral surface of the dielectric. The biggest cause of this plating blistering is that the adhesion strength between the dielectric substrate and the Cu coating is weak. Therefore, the Cu coating is N
2. Heat treatment in an inert gas such as Ar
No. 8-166806) or heat treatment in a reducing atmosphere or a weakly oxidizing atmosphere (JP-A-61-1).
Japanese Patent Laid-Open No. 21501) has been attempted to solve this problem. However, the method of heat treatment in these atmospheres increases the number of work steps, increases costs, and lacks mass productivity. Therefore, the present invention provides a method for forming an electrode for a dielectric resonator, which is economically excellent in eliminating the above-described plating swelling.

[0004]

In order to solve the above-mentioned problems, a method for forming an electrode of a dielectric resonator according to the present invention is to degrease the entire base material (surface) of a dielectric material and then chemically etch the surface. Roughening, followed by washing with water, sensitivity and activation. Next, electroless Ni-P is used as the base plating.
After plating to form a Ni-P film, electroless Cu
The electrode forming method is characterized in that a double-layered electrode layer having a thick Cu film is formed by plating.

[0005]

When the electroless Cu plating is performed after the dielectric substrate is chemically etched, coarse Cu particles are deposited on the etching traces, and these are in contact with each other to form a Cu film. At this time, many pores are present in the interface layer between the base material and the Cu film, which causes a decrease in adhesion strength, which in turn causes a plating blister. However, when the electroless Ni-P plating is performed as the undercoat after the chemical etching treatment as in the present invention, Ni-P grows in a fine film form from the initial deposition due to the etching marks, so that the dielectric substrate is not formed. The adhesion at the interface of the Ni-P coating is very good. When a Cu film is formed by electroless Cu plating on the surface of the Ni-P film which is the base, the Cu film does not grow in the form of coarse particles during the Cu film growth process.
-Grow in a fine film morphology similar to P film. Further, the growth of this Cu film is such that the thickness of the Ni-P film is 0.
It can be performed if the thickness is 1 μm or more, and the electric resistance of the Ni—P film does not affect the Q of the dielectric resonator if the film thickness is within about 1/10 of the skin depth (δε). still,
The skin depth (δε) is determined by Equation 1.

[0006]

[Formula 1]

Therefore, by such a simple method, the adhesion strength is improved, the plating swelling is eliminated, and the economically excellent dielectric resonator is realized.

[0008]

EXAMPLES Next, examples of the present invention will be described. Example 1 BaO-Sm2O3-CeO2-Pr6O11-TiO
16mm outer diameter, 4.4mm inner diameter, 1 height
Degrease the surface of the object processed to 8 mm with 10% NaOH,
Further, chemical etching is performed with an HF-HNO3 mixed solution (FIG. 2 (a)). After washing with water, Okuno Seiyaku Top OPC-80 catalyst (80 ml / l) and HCl
Sensitization treatment is performed with a mixed solution of (300 ml / l) (FIG. 2 (b)). Continued, H2SO4 (250ml
/ L) to activate the surface. Next, it is immersed in a top TMP chemical nickel bath (160 ml / l) manufactured by Okuno Seiyaku Co., Ltd. at 30 ° C. to deposit a Ni—P film as a base plating film (FIG. 3). A mixed solution of copper sulfate, formaldehyde, NaOH and a complexing agent (however,
Metallic copper 2 g / l, formaldehyde 3.4 g / l, pH
= 12.3, 55 ° C.) thick Cu plating treatment is performed,
A dielectric resonator (a cross sectional view is shown in FIG. 1) was obtained. Etching time at this time, thickness of underlying Ni film, plating blisters,
Table 1 shows the no-load Q and the determination result. The Q value was measured at a resonance frequency of 470 (MHz), and the judgment result was that the result when actually used for the resonator filter was
.Smallcircle intended Q value which is a prospect of viable ones of more than 900, as the plating blistering or not very small, × mark indicates anything other than it.

Example 2 BaO-Sm2O3-CeO2-Pr6O11-TiO
16mm outer diameter, 4.4mm inner diameter, 6 height
The product processed to 0 mm was plated as in Example 1, and the results are shown in Table 2 as in Example 1. The Q value is measured by the resonance frequency of 130 (MHz), and the judgment result is the same as in the first embodiment.
0, with minimal or no plating blister, ×
Marks indicate other things. In the comparative example, the sample No. is marked with *, and the sample Nos. 1 to 3 in Tables 1 and 2 are used.
Shows that an electrode is formed by conventional electroless Cu plating.

[0010]

[Table 1]

[0011]

[Table 2]

[0012]

INDUSTRIAL APPLICABILITY In the present invention, fine asperities are formed on a dielectric substrate by chemical etching, and a dense Ni-P film is formed on the etched surface by electroless Ni-P plating as a base plating to have a thickness of 0.1 μm or more. 1 / skin depth
By forming 10 or less and forming an electrode layer having a double structure in which a Cu film is formed by electroless Cu plating on the Ni-P film, the adhesion strength is improved and the plating swelling is eliminated. Furthermore, the manufacturing method is simple, mass productivity is excellent, and it is economically excellent. Further, it is possible to obtain an excellent Q of high frequency characteristics as a dielectric resonator.

[Brief description of drawings]

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

FIG. 2 is an explanatory diagram of an embodiment according to the present invention.

FIG. 3 is an explanatory diagram of an embodiment according to the present invention.

FIG. 4 is a general dielectric resonator.

[Explanation of symbols]

 1 electrode (Cu electrode or Ag electrode) 2 dielectric 3 catalyst (Pd + Sn) 4 Ni-P electrode 5 Cu electrode a etching mark

Claims (1)

[Claims] 1. A surface of a dielectric resonator ceramic is treated in the order of degreasing, chemical etching, sensitization, and activation, and then electroless Ni-P plating as a base electrode has a thickness of 0.1 μm or more and a skin depth of An electrode forming method for a dielectric resonator for microwaves, comprising forming an electrode layer having a double structure by forming a film having a thickness of 1/10 or less and then performing thick plating by electroless Cu plating.