JPH0818328A - Small antenna manufacturing method - Google Patents

Abstract

(57) [Abstract] [Purpose] It is an object to propose a manufacturing method suitable for mass production while reducing electrical loss. A metal conductor film 2 is deposited on the entire surface of a dielectric ceramic substrate 1 having a predetermined shape by plating, and then the unnecessary metal conductor film 2 is removed by etching to remove predetermined metal conductor film patterns 2a and 2b. , 3 are formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a small antenna suitable for mobile communication such as a mobile phone and a GPS (Satellite Positioning System) device.

[0002]

2. Description of the Related Art In recent years, in order to miniaturize an antenna with the miniaturization of mobile communication devices such as mobile phones and GPS devices, a dielectric ceramic substrate having a high dielectric constant (εr ≧ 10) is used in FIG. A small antenna as shown has been proposed.

To explain FIG. 2, the description of FIG.
And 1 is (Mg_1-XCa_X) TiO ₃(X = 0.05)
The composition powder was press-molded and fired at 1350 ° C.,
A dielectric ceramic substrate having a dielectric constant of 20 is shown.
The shape of the body ceramic substrate 1 is, for example, 12.5 mm × 1.
It is 2.5 mm × 6 mm.

Metallic conductor films 2a and 2b such as Cu are deposited on the upper and lower surfaces of the dielectric ceramic substrate 1, and a metallic conductor film 3 is formed to short-circuit the upper and lower metal conductor films 2a and 2b. .

When using this small antenna, FIG.
As shown in, the metal conductor film 2b on one surface, for example, the lower surface of this small antenna is mounted on the metal chassis 4 of the mobile phone, for example, and used as a reception-only antenna. In this case, it operates as a microstrip type inverted F antenna.

In such a small antenna, when the vertical length is a, the horizontal length is b, the relative dielectric constant of the dielectric ceramic substrate 1 is εr, and the wavelength of the received radio wave is λ, as shown in FIG. The relationship is established and, for example, a radio wave of 800 MHz is 12.5
It can be received by a small antenna having a size of mm × 12.5 mm × 6 mm.

[0007]

Conventionally, when manufacturing such a small antenna as shown in FIG. 2, a dielectric ceramic substrate has a predetermined shape, for example, 12.5 mm × 12.5 mm × 6.
After being formed and processed to have a thickness of mm, the metal conductor films 2a, 2b and 3 were adhered by baking a conductor paste or adhering a conductor plate.

The method of adhering this conductor plate to the dielectric ceramic substrate 1 is not suitable for mass production, and an adhesive layer is interposed between the metal conductor films 2a, 2b, 3 and the dielectric ceramic substrate 1. This adhesive layer has a small dielectric constant as compared with the dielectric ceramic substrate 1 and has a problem in antenna characteristics, and has a disadvantage that electric loss is large.

Also in the method of baking the conductor paste on the dielectric ceramic substrate 1, the conductor loss becomes large due to the influence of the glass frit contained in the conductor paste, and the steps of printing and baking the conductor paste are very troublesome. There was an inconvenience that was not suitable for mass production.

In view of the above, the present invention proposes a manufacturing method that reduces electric loss and is suitable for mass production.

[0011]

The method for manufacturing a small antenna of the present invention is unnecessary, for example, by depositing a metal conductor film 2 on the entire surface of a dielectric ceramic substrate 1 having a predetermined shape by plating as shown in FIG. By removing the metal conductor film 2 in a portion, predetermined metal conductor film patterns 2a, 2b,
3 is formed.

[0012]

According to the present invention, since the metal conductor film is formed by plating, the metal conductor film 2 can be simultaneously formed on the entire surface of the dielectric ceramic substrate 1, and the plating tank can be enlarged. Can be easily mass-produced, and since a predetermined metal conductor film pattern is formed by removing the unnecessary metal conductor film by etching, a good metal conductor film pattern can be easily obtained, which is suitable for mass production. .

Further, since the metal conductor film pattern is formed directly on the surface of the dielectric ceramic substrate 1, the electric loss of the metal conductor film pattern can be reduced and the antenna gain can be improved.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for manufacturing a small antenna of the present invention will be described below with reference to the drawings. First, as shown in FIG. 1A, a dielectric ceramic substrate 1 having a predetermined shape is prepared.

The dielectric ceramic substrate 1 is made of, for example, (Mg _{1- x} Ca _x ) TiO ₃ as a dielectric ceramic material.
The powder of the composition (X = 0.05) is press-molded and
It is obtained by firing at 350 ° C. to obtain a ceramic sintered body. The dielectric constant of the dielectric ceramic substrate 1 of this example is 20.

This dielectric ceramic substrate 1 is formed by grinding and cutting the above-mentioned ceramic sintered body to have a predetermined shape, for example, the length and width are 12.5 mm and the thickness is 6 mm.
And The size of this shape is determined by the wavelength λ of the radio wave used and the dielectric constant εr of the dielectric ceramic substrate used.

Next, a metal conductor film 2 is formed on the entire surface of the dielectric ceramic substrate 1 by a plating process as shown in FIG. 1B. This metal conductor is Cu, Ag, Ni, A
u or the like can be used. In this case, the thickness of the plating film, that is, the metal conductor film is set to about 20 μm in consideration of the skin effect at high frequencies such as 800 MHz.

Next, an example of the electroless copper plating step which is a plating step will be described. First, this dielectric ceramic substrate 1 is alkali-degreased using A-screen A-220 (manufactured by Okuno Chemical Industries Co., Ltd.), and then washed with water.

Next, hydrofluoric acid 40 is used to make the surface of the dielectric ceramic substrate 1 uneven in order to increase the adhesion.
%, 60% nitric acid mixed solution is used for etching, followed by washing with water.

Next, a pre-dip was carried out using a solution of hydrochloric acid 35%, and then a mixture of OPC80 Catalyst (manufactured by Okuno Seiyaku Kogyo) and a solution of hydrochloric acid 35% was used to carry out catalyzing to attach palladium to the surface. To do. After this catalyzing, it is washed with water.

Next, an accelerator X was added to a solution of sulfuric acid 97%.
Acceleration is performed in order to activate the catalyst using a mixture of (Okuno Pharmaceutical Co., Ltd.). After accelerating, wash with water.

Next, electroless plating of copper is performed using OPC Copper T (produced by Okuno Chemical Industries Co., Ltd.) as a copper electroless plating solution. This copper is plated with a predetermined thickness, for example 20 μm, and then washed with water.

Next, a rust preventive treatment is performed using a glycoat, and then a heat treatment is performed in an N ₂ atmosphere under the conditions of 300 ° C. × 10 minutes to form the dielectric ceramic substrate 1 and the copper plated film which is the metal conductor film 2. Try to increase the adhesion.

Next, as shown in FIG. 1C, a resist 5 is applied to a portion to be left as a metal conductor film pattern by using a screen printing technique, and then the resist 5 is dried.

As shown in FIG. 1C, the dielectric ceramic substrate 1 coated with the resist 5 is dipped in a ferric chloride solution as an etching solution to form an unnecessary portion of the metal conductor film 2 on which the resist 5 is not coated. The copper plating film is removed by etching (FIG. 1D). After this etching, it is washed sufficiently with water so that the etching solution is dropped.

Thereafter, as shown in FIG. 1D, a resist 5 applied on the metal conductor film on the dielectric ceramic substrate 1.
Is removed with an organic solvent such as acetone, and as shown in FIG. 1E,
A small antenna in which predetermined metal conductor film patterns 2a, 2b, 3 are formed on the surface of the dielectric ceramic substrate 1 can be obtained.

According to the method of manufacturing a small antenna according to this example, the metal conductor film 2 is formed by plating as described above, so that the metal conductor film 2 can be formed on the entire surface of the dielectric ceramic substrate 1 at the same time. The plating tank can be easily mass-produced by enlarging the plating tank, and the unnecessary metal conductor film is removed by etching to form the predetermined metal conductor film patterns 2a, 2b, 3 so that a good metal conductor can be formed. The film patterns 2a, 2b, 3 can be easily obtained, which is suitable for mass production.

Further, according to this example, the dielectric ceramic substrate 1
Since the metal conductor film patterns 2a, 2b and 3 are formed directly on the surface of the metal conductor film, the electric loss of the metal conductor film patterns 2a, 2b and 3 can be reduced, and there is an advantage that the antenna gain is improved.

The present invention is not limited to the above-described embodiments, and it goes without saying that various other configurations can be adopted without departing from the gist of the present invention.

[0030]

According to the present invention, the dielectric ceramic substrate 1
Since the metal conductor film 2 is formed by plating and the metal conductor film patterns 2a, 2b, 3 are formed by etching, it is easy to form good metal conductor film patterns 2a, 2b, 3 on the surface of the dielectric ceramic substrate 1. It is suitable for mass production.

Further, according to the present invention, since the metal conductor film patterns 2a, 2b, 3 are formed directly on the surface of the dielectric ceramic substrate 1, the metal conductor film patterns 2a, 2b, 3 are formed.
There is an advantage that the electric loss of the antenna can be reduced and the antenna gain is improved.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a method for manufacturing a small antenna of the present invention.

FIG. 2 is a perspective view showing an example of a small antenna.

[Explanation of symbols]

 1 Dielectric Ceramic Substrate 2 Metal Conductor Film 2a, 2b, 3 Metal Conductor Film Pattern 4 Metal Chassis 5 Resist

Claims (1)

[Claims] 1. A metal conductor film is deposited on the entire surface of a dielectric ceramic substrate of a predetermined shape by plating, and then the unnecessary metal conductor film is removed by etching to form a predetermined metal conductor film pattern. A method for manufacturing a small antenna, characterized in that