JPS60132402A - Electrode forming method of dielectric element for high frequency - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for forming electrodes of high-frequency dielectric elements having high film strength and a large Q value, such as coaxial resonators used in communication equipment and the like.

(Structure of conventional example and its problems) Coaxial resonators and the like are examples of filters used in the VHF band or UHF band, and dielectric elements with a high Q value are used in these filters. In order to maximize the Q% property of the dielectric element, it is necessary to consider device relationships and electrodes. In particular, the electrode has a close relationship with the life of the resonator, and it depends on the state of the interface between the electrode film and the surface of the dielectric bare hand.

Conventionally, as shown in FIG. 1, silver electrodes or plated copper electrodes are formed on the inner and outer peripheral surfaces of a dielectric having a coaxial structure. In the former case, silver paste was applied to the entire dielectric material and baked, and the relationship between the electrode thickness and the no-load Q of the resonator is shown in FIG. Here, QITl is the measured value, Q is the theoretical value,
E is the electrode thickness, and δ is the skin thickness. δ is given by the following formula ◇Here, f is the resonant frequency and μ is the magnetic permeability (
4X10"-7H/m), σ is the electrical conductivity of the electrode metal, and π is the circumference. From this, when the required electrode thickness is included when using a silver electrode, the resonant frequency Y 900 MJ
(If z, δ (skin thickness) is 2.1 μm.Q
To reduce the deterioration of the electrode, as shown in Figure 2, the electrode thickness should be 21 μm.
The above is necessary. In order to obtain this required electrode thickness, coating and baking must be performed at least three times, which requires a large number of man-hours. Furthermore, the adhesive strength is proportional to the amount of glass frit contained in the chain, but the amount of glass frit and the Q value are inversely proportional. FIG. 3 shows the relationship between the amount of glass frit, Q value, and adhesive strength. According to this, in order to satisfy a high Q value, the amount of glass frit should be l, Q
The mo of the dielectric resonator must be kept at 1% or less, and therefore the adhesive strength is 500 g r/an2 or less.

Copper electrode formation method by plating (Japanese Patent Application No. 53-157'1)
There is No. 2), but this has the disadvantage that the adhesive strength between the electrode and the dielectric surface is very weak, and the electrode peels off during heat cycle tests and the like. There is a method of increasing the surface roughness of the dielectric material by etching etc. to increase the adhesive strength, but the fourth method is
As shown in the figure, there is a problem that if the roughness is made, the no-load Q of the resonator deteriorates. Here, Qm is a measured value, Q (is a theoretical value, ρ is an average value of surface roughness), and δ is a skin thickness.

(Objective of the Invention) The present invention provides a method for forming an electrode of a high frequency dielectric element, in which the adhesive strength between the electrode and the dielectric surface is strong and the Q value is less deteriorated.

(Structure of the Invention) In order to achieve the above object, the invention is to form an electrode on the surface of a high-frequency dielectric element and then perform hot isostatic pressing.

(Description of Examples) Example 1 A B a T r 40 q ceramic was used as a sample, and a TEMλ/4 resonator was used as shown in FIG. Silver electrodes 6 were thinly coated on the inner circumferential portion 2, outer circumferential portion 3, and both end surfaces 4.5 of the dielectric body 1 having a coaxial structure, and baked at 800° C. for 10 minutes. The electrode thickness was 15 μm. The element was heated in Ar gas at 200°C to 700°C and 200 to 2000k.
g, hot isostatic pressing at 7 cm2. Thereafter, one end surface 4 of the element was removed, and the characteristics shown in FIGS. 5 and 6 were examined.

Example-2 The same element as in Example-1 was used as a sample, and the element was heated to H
Etching treatment was performed for 10 minutes using Fl0ωt% solution.

After forming a 4 μm copper film on the element by electroless copper plating, a copper electrode of 10 μm, total 14 μm, was formed by electrolytic copper plating. The element fAr gas at 700℃-1000℃ 97cm
2, hot isostatic pressing is performed, and then one end surface 4 is removed. The characteristics of the device are shown in the table.

As can be seen from the results shown in the table, the electrode forming method according to the present invention has a stronger electrode adhesion strength than conventional methods, and it is possible to provide a high frequency dielectric element with less Q deterioration.

In this example, silver and copper were used, but similar results were obtained with gold and other electrodes. In addition, in hot isostatic pressing, Ar
Gas was used, but heat-resistant oil, etc. (however, the operating temperature was m
Equivalent results were obtained using a temperature of 800° C.).

(Effects of the invention) Compared to conventional methods (baking, plating, etc.), the present invention can reduce the deterioration of the Q value and increase the adhesive strength of the electrode, improving reliability as a dielectric element for high frequencies. has improved. From the above, it is clear that the present invention is also applicable to various devices such as dielectric resonators.

[Brief explanation of drawings]

FIG. 1(a) is a cross-sectional view of a coaxial resonator for explaining one embodiment of the present invention, and FIG. 1(b) is a sectional view taken along A-A in FIG.
' Cross-sectional view, Figure 2 is a diagram showing the relationship between the silver mold thickness and the no-load Q of the resonator, and Figure 3 is the relationship between the glass frit component content in the silver electrode, electrode adhesion strength, and the no-load Q of the resonator. A diagram showing
Figure 4 shows the relationship between the surface roughness of the dielectric element and the no-load Q of the resonator, and Figures 5 and 6 show the relationship between the hot isostatic pressing conditions, electrode bonding strength, and the no-load Q of the resonator. FIG. 1... Dielectric, 2... Inner peripheral part, 3... Outer peripheral part, 4
．． 5... End face, 6... Electrode. Figure 1 (a) / (b) Figure 2 t/6 tjJ3 Figure 1 2 3 4 S1○2 agency last cut amount (mo!, 'lo) Figure 4, f/g Figure 5 H, 1, P pressure (km7c rr4) Figure 6 H1P pressure (kg/cm2)

Claims (2)

[Claims] (1) A method for forming electrodes of a high frequency dielectric element, which comprises forming electrodes on the surface of the high frequency dielectric element by full plating or baking, followed by hot isostatic pressing. (2) A method for forming an electrode of a high frequency dielectric element according to claim (1), wherein the electrode is made of Ag, Cu, or Au.