JPH02135806A - Manufacture of dielectric filter - Google Patents

Abstract

PURPOSE:To facilitate the forming of conductor film by forming one end of a coupling adjustment thin and long and choking one end at least prior to the impregnation of conductor paste. CONSTITUTION:The end of a thinner side of a coupling adjustment throughhole 22 is choked by a wax 23, then the face choked by the wax 23 is directed downward and the dielectric block 20 is impregnated to the conductor paste 40. Thus, the conductor paste is adhered only in the lower face, side face of the dielectric block 20 and in the throughhole 22 and no conductor paste is impregnated in the coupling adjustment throughhole 22 and no conductor film is formed. Then after the dielectric block 20 is dried, the conductor paste is baked and the wax packed in the coupling adjustment throughhole 22 is burned out and not left therein. The surface with no conductor film formed is polished in response to the operating frequency. Thus, the upper face is used as the open end face with exposed dielectric substance and an inner conductor 23 is formed in the throughhole 22 and an outer conductor 26 and a conductor film 27 for short-circuit end face are formed to the side face.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a dielectric filter, particularly a block-type dielectric filter in which a plurality of resonator units are integrally formed.

[Prior art]

Various dielectric band filters are used in the microwave band. In addition to conventional filters using individual cylindrical coaxial resonators, block-type filters that integrate a plurality of resonator units and utilize capacitive coupling and inductive coupling are attracting attention.

FIG. 6 is a front sectional view of such a dielectric filter, which includes two resonator units. Two through holes 61 are formed at intervals in the dielectric block 60, and an inner conductor is formed in the through holes 61. Further, an outer conductor 63 is provided on the outer peripheral surface of the dielectric block 60.
is formed. Further, a conductive film is similarly formed on the upper surface of the dielectric block 60, which becomes a short-circuit end surface 64. Only the lower surface of the dielectric block has no conductor film formed thereon, and is an open end surface where the dielectric material is exposed. Between the resonator units,
A coupling adjustment hole 65 is formed, and no conductive film is formed in this hole 65.

〔assignment〕

As mentioned above, there are parts of the dielectric block where a conductor film is formed and parts where a conductor film is not formed, and in particular, the coupling adjustment hole should not form a conductor et. It is not possible to form a film.

For this purpose, it is necessary to paint with a brush or to temporarily close the holes and immerse the material, which requires a large number of man-hours in the manufacturing process.

Therefore, attempts have been made to mold the joint by closing one end of the coupling adjustment hole, but this is difficult to mold and it is difficult to obtain dimensional accuracy.

The present invention aims to facilitate the formation of a conductive film by obtaining a dielectric block that closes one end of a coupling adjustment hole.

C Means for Solving the Problems] The present invention solves the above problems by forming one end of the coupling adjustment hole to be thin and closing at least one end before dipping the conductor paste, thereby facilitating the formation of the conductor film. It is something.

That is, in a method of manufacturing a dielectric filter, a plurality of resonator units each having a through hole in which an inner conductor is formed are integrally formed in a dielectric block, and holes for coupling adjustment are formed between the resonator units. A dielectric block having a through hole in which an inner conductor is formed and a through hole for coupling adjustment that is formed thin at one end is molded from a ceramic material, the dielectric block is fired, and the through hole for coupling adjustment is formed by firing the dielectric block. The dielectric block is characterized in that the dielectric block is immersed in a conductive paste with the narrow side closed and the side face down to form the inner conductor, the outer conductor, and the conductor film on the shorted end surface.

A dielectric filter is obtained by baking the conductive film thus formed. It is preferable to use a material that is combustible during baking as the material to be filled in the through-hole for bond adjustment.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

1 to 5 are front sectional views showing embodiments of the present invention. The basic composition is BaO-Ti02-Nd2O3,
A dielectric ceramic powder 19 such as a dielectric ceramic material to which Bidi30+z is added is filled into a mold 17 as shown in FIG. 1, and pressurized to form a dielectric block.

At this time, a mold 18 for forming a through hole for bond adjustment
There are two levels of thickness, with one end being thinner. To make it easier to mold, it is best to make the thickness change gradually.

As shown in FIG. 2, the dielectric block 20 made of the dielectric ceramic material molded as described above has a plurality of through holes 21 in which the inner conductors of the resonator unit will be formed later, and holes for coupling adjustment between them. A through hole 22 is provided.

After molding, this dielectric block is dried and fired.

After firing, the necessary conductor film is formed, but before that,
As shown in FIG. 3, through holes 22 for couplings t and N'l
The narrow end of the is closed with wax 23. The material for closing is not limited to wax, but a high viscosity wax such as "Atofix" may be used and filled into the through hole for bond adjustment using a dispenser or the like.

Next, as shown in FIG. 4, the dielectric block 20 is immersed in the conductive paste 40 with the surface covered with the wax 23 facing down. The depth of immersion must be such that the surface on the opening side of the through hole for bond adjustment is not immersed.

As a result, the conductive paste adheres only to the lower surface, side surface, and inside of the through hole 22 of the dielectric block 20, and the conductive paste does not penetrate into the through hole for the coupling adjustment hole, so that no conductive film is formed.

After drying the dielectric block 20 to which the conductive paste is attached, the conductive paste is baked. At this time, the wax filled in the through holes for bond adjustment will be burned and will not remain.

Usually, the surface on which the conductive film is not formed is polished depending on the frequency used. As a result, as shown in Figure 5,
The upper surface becomes an open end surface with exposed dielectric material, an inner conductor 25 is formed in the through hole 22, and an outer conductor 26 and a conductive film 27 of the shorted end surface are formed on the side surface. A dielectric block is obtained in which no conductor film is formed in the through holes 23 for coupling adjustment.

A dielectric unit in which a conductor is coated with a dielectric is inserted into the through hole in which the inner conductor of the dielectric block obtained as described above is formed, thereby forming an input/output coupling capacitor. The resonator units are coupled by capacitive coupling and inductive coupling to obtain a dielectric filter.

Note that the shape of the through hole for coupling adjustment is not limited to the above example, and one end may be formed thin and the thin side may be used as the short-circuited end surface of the dielectric filter. Capacitive coupling is at a minimum at the short-circuited end face, so even if the hole is thin, it has little effect on the characteristics.

〔effect〕

According to the present invention, at least one end of the bond adjustment hole of the fired dielectric block is closed, and a predetermined conductive film can be formed simply by immersing the dielectric block in a conductive paste. Therefore, the number of steps for forming the conductor film can be significantly reduced.

Further, since the coupling adjustment hole is passed through the molding, it is easy to obtain dimensional accuracy of the molding, which not only improves the yield but also provides a dielectric filter with stable characteristics.

[Brief explanation of the drawing]

1 to 5 are front sectional views showing embodiments of the present invention,
FIG. 6 shows a perspective view of a conventional dielectric filter. 20... Dielectric block 21... Through hole 22... Through hole 23 for coupling adjustment...
····wax

Claims (5)

[Claims] (1) A method for manufacturing a dielectric filter in which a plurality of resonator units each having a through hole in which an inner conductor is formed is integrally formed in a dielectric block, and holes for coupling adjustment are formed between the resonator units, A dielectric block having a through hole in which the inner conductor is formed and a through hole for coupling adjustment formed thin at one end is molded from a ceramic material, the dielectric block is fired, and the through hole for coupling adjustment is formed. A method for manufacturing a dielectric filter, comprising closing the narrow side of the dielectric block and immersing the dielectric block with the side face down in a conductive paste to form an inner conductor, an outer conductor, and a conductive film on the shorted end surface. (2) A method for manufacturing a dielectric filter in which a plurality of resonator units each having a through hole in which an inner conductor is formed is integrally formed in a dielectric block, and holes for coupling adjustment are formed between the resonator units, A dielectric block having a through hole in which the inner conductor is formed and a through hole for coupling adjustment formed thin at one end is molded from a ceramic material, the dielectric block is fired, and the through hole for coupling adjustment is formed. The narrow side of the dielectric block is closed, the dielectric block is immersed with the side face down in a conductor paste, and the conductor paste is baked to form an inner conductor, an outer conductor, and a conductor film on the shorted end surface. A method for manufacturing a dielectric filter. (3) The method for manufacturing a dielectric filter according to claim 1 or 2, wherein the narrow side of the through hole for bond adjustment is filled with wax having high viscosity to close it. (4) The method for manufacturing a dielectric filter according to claim 1 or 2, wherein the through holes for coupling adjustment are formed using molds having different diameters. (5) The method for manufacturing a dielectric filter according to claim 2, wherein the filled material is burned during baking of the conductive paste.