RU2643381C1 - Method of manufacturing of two-cavity monoblock casing of bandpass filter - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: invention may be applicable for making the bandpass filter (BPF). To fabricate the casing of a two-cavity monoblock of the bandpass filter, a powder mixture of LaAlO₃ is made in an amount of 30-40 wt % and CaTiO₃ is the rest. The plasticizer selected from the group consisting of stearin, paraffin and beeswax is added to the resulting mixture in an amount of 7.0 to 8.9 wt %. The finished mixture is poured under pressure and the obtained billet is annealed in two stages. The preliminary stage is carried out at a temperature of 100-300°C for 2-4 hours, and the final stage - at a temperature of 1300-1500°C for 4 hours.

EFFECT: increase of thermal stability and decrease in dielectric loss of bandpass filters, while maintaining the squareness factor at a level low enough to ensure high selectivity of bandpass filters, and the repeatability of radio engineering parameters in the mass production of bandpass filters.

3 ex

Description

The invention relates to the field of electronics and can be used in the manufacture of bandpass filters (PPF).

A known method of manufacturing a housing of a two-cavity monoblock bandpass filter, including obtaining a powder mixture containing barium carbonate, titanium oxide, samarium oxide, neodymium oxide and bismuth oxide, adding plasticizer (polyethylene glycol) to the resulting mixture, injection molding the finished mixture and annealing the resulting preform at a temperature of 1300-1500 ° C for 4-6 hours (see US 6900150 B2, 05/31/2005).

The disadvantage of this method is that its use leads to low thermal stability and a high level of dielectric loss in PPF.

The known method is adopted as the closest analogue of the claimed method.

The objective of the claimed invention is to provide a method of manufacturing a housing of a two-cavity monoblock bandpass filter, devoid of these disadvantages.

The result is a technical result consisting in increasing thermal stability and reducing the level of dielectric loss of PPF while maintaining the squareness coefficient at a level low enough to ensure high selectivity of PPF, as well as to ensure the repeatability of radio parameters in serial production of PPF.

Specifically, the specified technical result is achieved by creating a method of manufacturing a housing of a two-cavity monoblock band-pass filter, comprising obtaining a powder mixture of LaAlO ₃ in an amount of 30-40 wt. % and CaTiO ₃ - the rest, adding to the resulting mixture a plasticizer selected from the group including stearin, paraffin and beeswax, in an amount of 7.0-8.9 wt. %, casting the finished mixture under pressure and annealing the obtained preform in two stages, with the preliminary stage being carried out at a temperature of 100-300 ° C for 2-4 hours, and the final stage at a temperature of 1300-1500 ° C for 4 hours.

The use of injection molding in the manufacture of billet housings for two-cavity monoblocks PPF ensures the repeatability of radio engineering parameters in serial production of PPF by minimizing the use of this technology of the number of process parameters that affect the quality of the finished product.

Adding plasticizer to the mixture in an amount less than 7.0 wt. %, makes it impossible to use injection molding bodies for forming blanks.

Adding plasticizer to the mixture in an amount greater than 8.9 wt. %, leads to an increase in pore size and the total porosity of the workpieces, which significantly increases the coefficient of rectangularity of the PPF.

The use of stearin, paraffin or beeswax as a plasticizer provides high fluidity of the finished mixture, which makes it possible to use a plasticizer in an amount of up to 7.0 wt. %

Below are examples of the implementation of the claimed method.

Example 1

Receive (by grinding in a ball mill) a powder mixture of LaAlO ₃ in the amount of 35 wt. % and CaTiO ₃ - the rest.

To the mixture add paraffin in an amount of 7.8 wt. %

The finished mixture is poured under pressure using a mold. The obtained preforms are annealed in two stages. The first stage is carried out at a temperature of 250 ° C for 2 hours, the second stage is carried out at a temperature of 1350 ° C for 4 hours.

Example 2

Get (analogously to example 1) a powder mixture of LaAlO ₃ in the amount of 30 wt. % and CaTiO ₃ - the rest.

To the resulting mixture add stearin in an amount of 7.1 wt. %

The finished mixture is poured under pressure using a mold. The obtained preforms are annealed in two stages. The first stage is carried out at a temperature of 180 ° C for 3 hours, the second stage is carried out at a temperature of 1470 ° C for 4 hours.

Example 3

Get (similar to examples 1 and 2) a powder mixture of LaAlO ₃ in an amount of 40 wt. % and CaTiO ₃ - the rest.

In the mixture add stearin in an amount of 7.8 wt. %

The finished mixture is poured under pressure using a mold. The obtained preforms are annealed in two stages. The first stage is carried out at a temperature of 260 ° C for 4 hours, the second stage is carried out at a temperature of 1320 ° C for 4 hours.

The finished body (in particular, having the shape disclosed in US 4,673,902) is ground to the required size, depending on the given center frequency of the PPF. Then, the holes of the indicated case are metallized with silver paste to form a two-cavity monoblock. Then (by screen printing) metallization of the monoblock faces is carried out with the formation of a topological pattern on them. The resulting band-pass filter is mounted (by surface mounting) on a printed circuit board, similar to US Pat. No. 4,673,902.

In order to prevent external mechanical influences and foreign particles (solder, flux) entering the PPF, a cover is mounted over the two-cavity monoblock.

Claims (1)

A method of manufacturing a two-cavity monoblock housing of a band-pass filter, including obtaining a powder mixture, adding a plasticizer to the resulting mixture, molding the finished mixture under pressure, and annealing the resulting preform, characterized in that a LaAlO ₃ mixture in an amount of 30-40 wt. % and CaTiO ₃ - the rest, while using a plasticizer selected from the group including stearin, paraffin and beeswax, which are added to the resulting mixture in an amount of 7.0-8.9 wt. %, and the obtained preform is annealed in two stages, while the preliminary stage is carried out at a temperature of 100-300 ° C for 2-4 hours, and the final stage is carried out at a temperature of 1300-1500 ° C for 4 hours.