JPH0315841B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a combline filter or an interdigital filter formed by providing an electrode film on a dielectric material.

Conventionally, there are combline filters as shown in FIGS. 1 to 5.

In the figure, 1 is a rectangular parallelepiped dielectric block made of a titanium oxide ceramic dielectric, and the block 1 has through holes 2 to 6 extending in one direction.
is provided. Conductive films 7 to 1 are provided on the inner surfaces of holes 2 to 6.
1 is provided. Outer surface electrodes 12 and 13 are provided on the four sides and bottom of the block 1. Therefore, the filters shown in FIGS. 1 to 5 function as combline filters in which the conductive films 7 to 11 are mutually coupled as 1/4λ resonant electrodes. In this filter, the external coupling unit 1
4 and 15 are press-fitted respectively. unit 1
Reference numerals 4 and 15 have a dielectric material such as plastic or titanium oxide ceramic that is approximately cylindrical and has a flange portion, and a conducting wire that passes through the axis of the dielectric material. They are capacitively coupled via.

In conventional filters with this structure, electrodes must be provided by leaving one of the six outer surfaces of block 1 (the surface shown in Figure 1) with metallization, so the metallization must be applied by hand. It was carried out at Hand painting itself has poor work efficiency, and
If it got stuck in places where it shouldn't, it had to be wiped off, making it unsuitable for mass production and making it impossible to reduce costs.

Therefore, an object of the present invention is to provide a method for manufacturing a filter suitable for mass production.

Another object of the invention is to provide a method for manufacturing smaller filters.

Another object of the invention is to provide a particularly advantageous manufacturing method for manufacturing interdigital filters.

The gist of the invention is to prepare two dielectric blocks each having a groove on one main surface, cover the entire surface of each dielectric block with an electrode film, and then cut the groove on one main surface. This is a method for manufacturing a filter in which the electrode films of the parts to be removed are removed, and the surfaces from which the electrode films have been removed are glued together.

The above-mentioned objects and other objects and features of the present invention will become more apparent from the following embodiments.

6 to 9 are diagrams for explaining the method of this embodiment.

In the method of this embodiment, first, two dielectric blocks 21 and 22 are prepared. It is assumed that these two dielectric blocks 21 and 22 have the same size as the conventional block 1 when they are glued together. In other words, the blocks 21 and 22 are rectangular parallelepipeds made of titanium oxide ceramic dielectric and have a size obtained by vertically dividing the block 1. Therefore, one main surface 23 of block 21 is provided with semicircular grooves 24-28, and one main surface 29 of block 22 is also provided with semicircular grooves 30-34. As will be described later, the grooves 24 and 30, the grooves 25 and 31, and the grooves 26
and groove 32, groove 27 and groove 33, and groove 28 and groove 34 are combined to form a circular hole shape corresponding to conventional holes 2 to 6.

Next, a conductive film 3 is formed on the entire surface of the dielectric blocks 21 and 22 by plating, printing, brushing, dip coating, powder coating, etc. as shown in FIG.
Form 5,36. In this case, the open surface may be covered to prevent the conductive film material from adhering to it.

After that, one main surface 2 of blocks 21 and 22
The conductor film attached to the portions other than the grooves 24 to 28 and 30 to 34 of No. 3 and 29 and the conductor film attached to the surface corresponding to the open surface are removed by polishing or the like. Then, the parts of the main surfaces 23 and 29 from which the electrode films have been removed are glued together using glass glaze or adhesive as shown in FIG. 8, and a conductor film is baked if necessary.

The block formed in this manner is functionally the same as the conventional block 1. In other words, holes 2 to 6 are formed by gluing and integrating a pair of blocks 21 and 22, and the inner circumferential surface thereof has 1/2
There are conductive films 7 to 11 each functioning as a 4λ resonance electrode. Further, outer surface electrodes 12 and 13 are present on the block surfaces excluding the surface corresponding to the open surface, that is, on the four side surfaces and the bottom surface. Therefore, for example, as in the conventional example, the external coupling units 14 and 15 are used to couple the circuit to the external circuit.
It works as a combline filter using a 4λ resonator.

This method of forming a conductive film using a dielectric block divided into two parts can be carried out with a combline filter as in the above embodiment, but is particularly advantageous in the case of an interdigital filter. In other words, even if an interdigital filter is constructed using dielectric blocks, it cannot be put to practical use because it is difficult to mold ceramic powder to have closed-ended holes. However, according to the present invention, since it is only necessary to form grooves having a semicircular cross section on the outer surface, molding becomes easy and an interdigital filter using dielectric blocks can be put to practical use.

Even if two halves of a dielectric block are simply glued together in this way, since the mode in which the electric lines of force do not intersect with the bonding surfaces is used, there is no negative effect on the electrical properties. .

In both the combline filter and the interdigital filter, the hole shape is not limited to a circular cross section, but may be any conventionally known shape such as a square cross section.
Further, each resonator may be of a stepped impedance type having an inductive portion and a capacitive portion having different inner diameters.

As is clear from the above embodiments, according to the present invention, there is no need to hand coat the conductor film material for both the comline filter and the interdigital filter, so machine coating can be adopted, mass production is possible, and cost is reduced. down can be achieved. Further, according to the present invention, a step impedance resonator can be employed, and a small filter can be provided.

Furthermore, interdigital filters, which have conventionally been difficult to manufacture using dielectric blocks, can be easily manufactured, and parts can be shared with combline filters. The present invention can also be applied to a device in which a cavity for adjusting the degree of coupling is provided between resonant electrodes, as disclosed in Japanese Patent Application Laid-Open No. 58-9401.

[Brief explanation of the drawing]

Figures 1 to 5 show conventional filters, with Figure 1 being a plan view, Figure 2 being a front view, Figure 3 being a side view, and Figure 4 being a side view.
The figure is a plan view, FIG. 5 is a sectional view, and FIGS. 6 to 9 are sectional views of an embodiment of the invention. 21, 22 are dielectric blocks, 23, 29 are one surface, 24-28, 30-34 are grooves, 35, 3
6 is a conductor film.

Claims (1)

[Claims] 1. Prepare two dielectric blocks with grooves on one main surface, cover the entire surface of each dielectric block with an all-polar film, and then apply an electrode to the part of the one main surface other than the grooves. characterized in that each film is removed and the surfaces from which the electrode films have been removed are glued together,
A method for manufacturing a filter using a dielectric.