JPH1041702A - Electrode formation method for dielectric filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To constitute a dielectric filter having stable filter characteristics by applying an additional conductive layer to both end parts of a short-circuited end face, stipulating the length of a belt-like electrode removal part and thus forming a belt-like non-electrode part for coupling. SOLUTION: Screen printing is executed to both end parts of the short- circuited end face, the additional conductive layer 23 is formed and the length of the belt-like electrode removal part 22 is corrected by the added conductive layer 23. Then, the belt-like non-electrode part 10 for coupling whose length is accurately stipulated is formed. That is, by shaving the belt-like electrode removal part 22 over the entire width along the columnarly providing direction of through-holes 4a and 4b on the short-circuited end face, applying the additional conductive layer 23 on both end parts of the short-circuited end face further and stipulating the length of the belt-like electrode removal part 22, the belt-like non-electrode part 10 for coupling is formed. Since the belt-like electrode removal part 22 is formed by grinding in such a manner, blotting and thinning like the case of screen printing is avoided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a dielectric filter having a plurality of resonators arranged in parallel.

[0002]

2. Description of the Related Art A plurality of resonators are provided on a dielectric ceramic block by coating an inner conductor on an inner peripheral surface of a through hole, and a required outer peripheral surface excluding an open end surface where the through hole is opened. Various dielectric filters in which an outer conductor is coated have been proposed.

On the other hand, in the above-described configuration, a band-shaped non-electrode portion for coupling is formed on the short-circuit end surface along the direction in which the through holes are arranged in order to couple the respective resonators. A configuration in which resonators are magnetically coupled to each other has been proposed.

[0004]

As described above, a dielectric filter provided with a band-shaped non-electrode portion for coupling has conventionally been disclosed.
The band-shaped non-electrode portion was formed by printing the electrode layer in a required shape using a screen pattern having a non-coating region corresponding to the non-electrode portion. However, when screen pattern printing is performed in this way, bleeding occurs at the boundaries of the electrode layers, blurring occurs due to variations in ink density, and further, the relative position with respect to the block varies minutely, resulting in misalignment. Therefore, there is a problem that the filter characteristics vary widely, and the yield is poor.

An object of the present invention is to eliminate such a problem of the conventional configuration.

[0006]

According to the present invention, in the above-mentioned dielectric filter, a strip-shaped electrode removing portion is formed on the short-circuited end face so as to cover the entire width of the block along the direction in which the through holes are arranged. Further, an electrode is formed on the dielectric filter by applying a retrofit conductive layer to both ends of the short-circuited end face and defining the length of the strip-shaped electrode-removed portion to form a band-shaped non-electrode portion for coupling. Is the way.

In this method, since the strip-shaped electrode removing portion is performed by grinding, there is no blurring or blurring as in the case of screen pattern printing. In addition, both ends of the strip-shaped electrode removing portion exceed the through holes on both outer sides,
It is known that the connection weakens on reaching the side end face of the block. However, in the above-described method, the length of the retrofitting conductive layer can be accurately and precisely mass-produced by coating, and a dielectric filter having good characteristics can be manufactured.

[0008]

Embodiments of the present invention will be described with reference to the accompanying drawings. 1 and 2 show three resonators 3a, 3b, 3
b shows an embodiment in which three-stage dielectric filters 1 each having a resonator are formed by b. Here, the dielectric ceramic block 2 has a substantially rectangular parallelepiped shape made of a titanium oxide-based ceramic dielectric, and the resonators 3a, 3b, 3b are arranged in parallel with each other. These resonators 3a, 3b, 3
b denotes the inner conductors 5, 5, 5 in the through holes 4a, 4b, 4b, respectively.
And the through holes 4a, 4
The outer conductor 7 is coated on a required outer peripheral surface except for the open end surface 8 where b and 4b are opened, and this is used as a shield electrode. The resonators 3a, 3b, 3b are made to substantially match the resonance length dimension corresponding to λ / 4 of the resonance frequency.

Next, the main part of the present invention will be described. As shown in FIG. 2, the short-circuit end face 9 facing the open end face 8 along the direction in which the through holes 4 a, 4 b, 4 b are arranged in the right and left sides of the through-holes 4 a, 4 b, 4 b. The two end portions of the block 10 are formed so as to have a length that does not reach the both side ends 2a, 2b of the block 2 beyond the outer through holes 4b, 4b. The resonators 3a, 3b, 3b are magnetically coupled by the coupling non-electrode portions 10, 10. Since the magnetic field coupling force between the resonators is determined by the length of the band-shaped non-electrode portions 10, 10, the length is as follows.
Must be determined as accurately as possible.

In such a configuration, the band-shaped non-electrode portions 10 for coupling are formed by the electrode forming method shown in FIG.
Will be formed.

That is, first, a titanium oxide-based ceramic dielectric powder is put into a mold, the outer shape of the dielectric ceramic block 2 is determined by press working, and after taking out from the mold, the through holes 4a, 4b, 4b are formed. After being formed and removed from the mold, it is sintered.

Next, the sintered body is subjected to a doping (dipping) or the like (FIG. 3A).

Thereafter, on the short-circuit end face 9, along the direction in which the through-holes 4a, 4b, 4b are arranged, the electrode layer 21 applied on the entire short-circuit end face 9 by the above-mentioned doping (dipping). With a diamond cutter etc.
(FIG. 3B), thereby forming the strip-shaped electrode removing portions 22 and 22.

Then, as shown in FIG.
Screen printing on both ends of the conductive layer 23,
23, the lengths of the strip-shaped electrode removing portions 22, 22 are corrected by the post-attachment conductive layers 23, 23, thereby forming the band-shaped non-electrode portions 10, 10 for coupling whose lengths are precisely defined. I do. The process of forming the additional conductive layers 23 is shown in FIG.
As shown by C, a large number of dielectric filters 1 are connected to each other, and a rear conductive layer 2 is provided on both sides along the row direction.
By forming 3, 23 by screen printing,
Mass production can be measured.

In this method, after forming an electrode layer 21 which is to be a part of the outer conductor 7 by doping (dipping), strip-shaped electrode removing portions 22, 22 are formed on the short-circuit end face 9 and then further formed. Since the conductive layers 23, 23 are applied to define the length and the band-shaped non-electrode portions 10, 10 for coupling are formed, there is no bleeding at the boundary line between the band-shaped non-electrode portions 10, 10 for coupling. In addition, there is no fuzz in the outer conductor 7 on the short-circuit end face 9.
For this reason, through the band-shaped non-electrode portions 10 for coupling,
The resonators 3a, 3b, 3b can be magnetically coupled to each other stably. In addition, even if the retrofit conductive layers 23 are formed by screen printing as described above, the non-electrode portion 1
In order to set the dimensions by filling both ends of 0 and 10 with a conductive layer, it is merely an overcoating.
It does not cause bleeding.

In addition, the dielectric filter 1 having this configuration includes the input / output pads 12, 12 shown in FIG.
b, 3b, are formed so as to be insulated from the outer conductor 7 at positions facing the open ends, so that the input / output pads 12, 12 can be electrically connected to the electric circuit on the printed circuit board.
b, 3b and the input / output pads 12, 12, the coupling capacitance C ₀ ,
C ₀ is generated.

FIG. 4 shows an equivalent circuit of the above configuration, where L ₁ and L ₁ indicate the magnetic field coupling by the non-electrode portions 10.

[0018]

As described above, according to the present invention, the strip-shaped electrode removing portion is formed on the short-circuit end face over the entire width along the direction in which the through-holes are arranged, and further, retrofits are provided at both ends of the short-circuit end face. A method in which a conductive layer is applied and a band-shaped non-electrode portion is formed by defining the length of the band-shaped electrode removed portion, and the band-shaped electrode removed portion is ground by screen printing. There is no blurring or blurring as in the case of (1).

Accordingly, the coupling amount is constant, and a dielectric filter having stable filter characteristics can be constructed.
Has an excellent effect.

[Brief description of the drawings]

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

FIG. 2 is a perspective view of the dielectric filter 1 as viewed from below.

FIG. 3 is an explanatory view showing a process of forming the band-shaped non-electrode portions for coupling 10, and is a perspective view of a lower portion of the dielectric filter 1.

FIG. 4 is an equivalent circuit diagram.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Dielectric filter 2 Dielectric porcelain block 3a, 3b, 3b Resonator 4 Through-hole 5 Inner conductor 7 Outer conductor 8 Open end face 9 Short-circuit end face 10, 10 Bonding non-electrode part 22 Band-shaped electrode removing part 23 Retrofit conductive layer

Claims (1)

[Claims] 1. A plurality of resonators formed by coating an inner conductor on an inner peripheral surface of a through hole in a dielectric ceramic block, and a required outer peripheral surface excluding an open end surface where the through hole is opened. A dielectric band-shaped non-electrode portion is formed on the short-circuit end face along the direction in which the through holes are arranged. Then, the strip-shaped electrode removal part is cut to cover the entire width of the block,
A method for forming an electrode for a dielectric filter, wherein a non-electrode part for coupling is formed by applying a retrofit conductive layer to both ends of a short-circuit end face and defining the length of a strip-shaped electrode removal part.