JPH05167319A - Production of strip line type filter containing plural center conductors set on plastic film plate - Google Patents

Abstract

PURPOSE:To improve the performance and the productivity of the subject filters by forming a metallic pattern on a plastic film as a center conductor and fixing the ceramic plates covered with the metallic conductors on both sides of the metallic pattern. CONSTITUTION:A metallic pattern 7 is formed on a plastic film plate 3 having the proper strength, heat resistance and electric insulation properties by the electrolysis or the electroless plating. Then the plate 3 containing the pattern 7 is fixed between the ceramic surfaces of the ceramic plates 1 and 2 which are covered with the metallic conductors 4 and 5 respectively. Such a molded matter is vertically separated into the strip line type filters of each prescribed shape.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave band or quasi-microwave band stripline filter used in radio equipment and the like, and more particularly to a method of manufacturing a stripline filter having excellent insertion loss characteristics.

[0002]

2. Description of the Related Art FIG. 3 shows a perspective view of a conventional stripline filter using ceramics, and FIG. 4 shows an exploded perspective view of a conventional stripline filter using ceramics.

As shown in FIG. 3, in the conventional stripline filter, the other side ceramic surface of the ceramic plate 1 on which the metal conductor 4 is entirely covered on one side, and the metal conductor 5 on one side. The fired metal pattern 6 is formed on the other side of the ceramic plate 2 covered by the whole surface by the thick film printing method, and the metal pattern 6 of the ceramic plate 2 is superposed on the ceramic surface. In this case, it is general to take a step of simultaneously firing the ceramic plate 2 and the fired metal pattern 6 for the purpose of improving the productivity, and to apply the fired metal pattern 6 printed on the ceramic plate 2 to the fired metal pattern 6. Is equipped with a half-wavelength or one-wavelength stripline resonator (not shown), each of which is coupled by magnetic field coupling. Goods were often seen.

In this case, the high frequency power input from the input end travels through the fired metal pattern 6 which is sandwiched between the ceramic plate 1 and the ceramic plate 2 and is first closest to the input antenna. Coupled to the first stripline resonator (not shown), but then to the next stripline resonator closest to the first stripline resonator closest to the input antenna above, Furthermore, it is a very general operation to repeat such a history one after another, passing through the resonator and finally reaching the output end. It is often the case that only frequency components in the vicinity of the resonance frequency of the resonator are transmitted, which constitutes a bandpass filter.

[0005]

However, in the above stripline type filter, since the fired metal pattern 6 itself of the stripline type filter resonator is formed by the thick film printing method, the fired pattern 6 is formed.
Since the composition of the glass used in the thick film printing method is likely to remain in the firing pattern during the firing operation for forming the firing pattern, the conductivity of the central conductor forming the firing metal pattern 6 is low. However, the Q value of the resonator, which is an index representing the sharpness of the resonance phenomenon, has always been lowered.

Further, as described above, the ceramic plate 2
When the fired metal pattern 6 is formed on the ceramic plate, the ceramic plate 2 and the fired metal pattern 6 are generally fired at the same time for the purpose of improving productivity. It is unavoidable that a mixed region of ceramics and metal is generated at the interface between 2 and the fired metal pattern 6, but this mixed region causes a large insertion loss in the high frequency band.

[0007] For the purpose of avoiding the above-mentioned defects, a metal conductor formed by a thin film conductor manufacturing method such as a vacuum vapor deposition method or a sputtering method has been used, but in this case, a microwave band or Since the thickness of the film cannot be sufficiently set to about 1 μm for the use of the quasi-microwave band, the Q value of the resonator, which is an index showing the sharpness of the resonance phenomenon, also decreases. Was always.

A decrease in the Q value of the resonator, which is an index representing the sharpness of the resonance phenomenon, immediately increases the insertion loss, which is a measure of the filter function. Therefore, in the market, a function aimed at improving the filter function is provided. There has been a long-felt demand for the emergence of improvement methods.

An object of the present invention is to solve the above problems and to provide a stripline filter which has a small insertion loss of microwaves passing through the apparatus and is easy to manufacture.

[0010]

Means for Solving the Problems The inventors of the present invention have conducted extensive research into means for solving the above-mentioned problems, and as a result, have found that two ceramic plates 1 each of which is covered with metal conductors 4 and 5 on one entire surface thereof. After the plastic film 3 having a plurality of metal patterns 7 of the central conductor formed on one surface is inserted and fixed between the ceramic surfaces on the other side of each of No. 2 and No. 2 to form a laminated molded body L, the molded body L is predetermined. The present invention was found to solve the problems by cutting into a strip-line type filter by cutting it into the shape described above.

[0011]

The present invention employs the metal pattern 7 formed by electrolytic or electroless plating on the plastic film plate 3 having appropriate strength, heat resistance and electric insulation as the central conductor of the stripline type filter. Therefore, there is no possibility that the mixed area of ceramics and metal pattern, which is recognized in the conventional example, will occur, and the wall thickness of the subject center conductor can be sufficiently taken. Not only has it been possible to provide a stripline filter that requires only a small loss and is easy to manufacture, but it has also been possible to greatly improve its productivity by using a long tape.

Further, according to the present invention, since the method of treating a plurality of central conductor patterns with the plastic film 3 at a time is adopted, the productivity can be greatly increased.

[0013]

EXAMPLES Examples of the present invention will be described in detail below.

FIG. 1 is an exploded perspective view of a stripline type filter according to an embodiment of the present invention, and FIG. 2 is a perspective view of a stripline type filter molded body according to an embodiment of the present invention in a longitudinally separated state. .

A plastic film plate having a thickness of 50
μm, width 100 mm, length 100 mm
A copper film having a thickness of 20 μm is provided on one side of the polyimide film plate by electroless plating, and a predetermined pattern 7 corresponding to 800 filters is formed by photoetching on the copper film. It was formed on a film, and a copper film having a thickness of 0.5 mm was thick-film printed on one surface of the film to obtain a plastic film 3. Next, the plate was inserted between two dielectric ceramic plates 1 and 2 each having a width of 100 mm, a length of 100 mm, and a relative dielectric constant of 80 (FIG. 1). Used when an IC or the like is manufactured by integrally fixing a single piece of dielectric ceramics plate 1 and 2 and a plastic film 3 having a predetermined pattern 7 formed on a copper film using a polyimide adhesive. The above-mentioned laminated molded body L is longitudinally separated into stripline type filters one by one using a dicing saw (Fig. 2) to produce a stripline type filter having a 3 dB bandwidth of 16 MHz and a center frequency of 900 MHz. When the insertion loss of the wave was measured, it was only 1.5 dB, which was a significant improvement in performance as compared with the conventional value of 5 dB, and its manufacturing time was less than that of the conventional method. Be dispensed with 80% has become possible.

[0016]

When the present invention is put into practice, it becomes possible to improve the performance of the stripline type filter and to greatly improve the productivity in manufacturing the stripline type filter. There are great contributions to the industry related to telephones, cordless telephones, professional wireless devices, and so on.

[Brief description of drawings]

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

FIG. 2 is a perspective view of a stripline type filter molded body according to an embodiment of the present invention in a longitudinally separated state.

FIG. 3 is a perspective view of a conventional stripline filter.

FIG. 4 is an exploded perspective view of a conventional stripline filter.

[Explanation of symbols]

 1: Dielectric ceramic plate. 2: Dielectric ceramic plate. 3: Plastic film. 4: Metal conductor. 5: Metal conductor. 6: Metal pattern. 7: Metal pattern. L: Laminated body.

Claims (1)

[Claims] 1. A stripline filter comprising a combination of a ceramics plate and a metal conductor, wherein one surface of the two ceramics plates is covered with the metal conductor on the other side of each of the two ceramics plates. After inserting and fixing a plastic film having a plurality of stripline center conductors formed into a molded body, the molded body is cut into a predetermined shape to form a stripline filter. A method for manufacturing a stripline filter in which a central conductor is placed on a plastic film plate.