Wave transmission lines and networks – Coupling networks – Wave filters including long line elements
Reexamination Certificate
1999-03-09
2001-02-13
Pascal, Robert (Department: 2817)
Wave transmission lines and networks
Coupling networks
Wave filters including long line elements
C333S134000, C029S840000, C029S851000
Reexamination Certificate
active
06188299
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an integral type dielectric filter device having two unit filters of different types with different pass frequency bands such as a duplexer that is suitably be used for a portable telephone set. It also relates to a method of manufacturing such a dielectric filter device.
PRIOR ART
Japanese Patent Kokai No. 63-311801 discloses a dielectric filter device comprising a plurality of resonators arranged in parallel in a direction on a dielectric ceramic block which has outer peripheral surface coated with an grounding conductor except an open-circuit end surface where through holes of the resonators are exposed. The dielectric filter device is mounted on a printed circuit substrate or board provided with a coupling circuit which is coupled to the related resonators. The dielectric filter and the substrate are housed in a metal casing. Various similar dielectric filter devices have also been proposed to date.
In such a dielectric filter device, each of the resonators is provided with a metal terminal driven into it in order to capacitively couple the resonators and the metal terminals are connected to a capacitor circuit formed on the printed circuit substrate so that, as a whole, the dielectric filter device requires a cumbersome operation of connecting wires and involves a considerable number of assembling steps reflecting a complicated circuit design and a clumsy circuit arrangement.
In an attempt to avoid the above problem, the inventors of the present patent application proposed a dielectric filter device comprising a resonator body in which a plurality of resonators are arranged in parallel in a same direction and each of the resonators includes a through hole whose inner surface is coated with an inner conductor, and a laminated circuit arrangement having connection terminals which is realized by laminating a plurality of dielectric sheet materials and arranged on the open-circuit end surface of the resonator body, each of the resonators being electrically connected to the corresponding connection terminals of the resonator body on the bonded surface (Japanese Patent Kokai No. 9-257766).
With the arrangement wherein a laminated circuit arrangement is bonded to the open-circuit end surface of the resonator body, the respective terminals also have to be electrically connected with each other. While the use of an electrically conductive adhesive agent may be conceivable, such an agent normally does not provide a sufficient bonding effect and the electric connections are apt to become disrupted by mechanical impact.
It is, therefore, an object of the present invention is to provide a dielectric filter device that is capable of overcoming these problems.
Another object of the present invention is to provide a method of manufacturing such a dielectric filter device.
SUMMARY OF THE INVENTION
According to one aspect of the invention, there is provided a dielectric filter device comprising a resonator body in which a plurality of resonators are provided in parallel in a same direction, each having a through hole whose inner surface is coated with an inner conductor, and a laminated circuit arrangement including a plurality of dielectric sheet materials which are laminated one after another and bonded to an open-circuit end surface of the resonator body, each of the resonators being electrically connected with a corresponding one of connection terminals of the resonator body, on the open-circuit end surface, wherein the filter device comprises solder members arranged between the resonator body and the laminated circuit arrangement for bonding the laminated circuit arrangement and the resonator body and electrically connecting the connection terminals of the laminated circuit arrangement with the respective resonators of the resonator body.
Preferably, the solder members may be provided by arranging solder balls between the resonator body and the laminated circuit arrangement in such a manner that each solder ball is positioned between an open-circuit end of each of the through holes of the resonators of the resonator body and a corresponding one of the connection terminals of the laminated circuit arrangement and melting/solidifying the solder balls.
With the above arrangement, as the solder balls are molten and subsequently solidified, they tend to make a uniformly dotted solder section due to the surface tension of the molten solder, which provides a reliable mechanical bond and also a reliable electric connection for the resonator body and the laminated circuit arrangement. Additionally, the entire bonding process can be easily controlled because it simply consists in arranging solid solder balls at appropriate positions before melting and solidifying them.
When such a dielectric filter device is to be realized as an integral type dielectric filter device having two unit filters of different types, the resonators of the resonator body are divided into two groups, a first filter section and a second filter section. A dielectric duplexer device can be obtained by using the first and second filter sections respectively as a receiver section and a transmitter section.
According to another aspect of the invention, there is provided a method of manufacturing a dielectric filter device comprising the steps of:
preparing a resonator body by arranging a plurality of resonators in parallel in a same direction, each having a through hole whose inner surface is coated with an inner conductor layer;
preparing a laminated circuit arrangement by stacking a plurality of dielectric sheet members each having a desired circuit pattern and sintering them, the laminated circuit arrangement being provided with a plurality of connection terminals on one of outer surfaces which is to be bonded to an open-circuit end surface of the resonator body; and
bonding the resonator body and the laminated circuit arrangement together and electrically connecting the resonators and the corresponding connection terminals by arranging a solder ball between a open-circuit end of each of the resonators of the resonator body and the corresponding connection terminals of the laminated circuit arrangement and melting/solidifying the respective solder balls.
When bonding the dielectric filter body and the laminated circuit arrangement to each other, preferably, solder balls are supported by the open-circuit ends or edges of the through holes of the resonator body and the resonator body is placed in a holding hole of a jig with the laminated circuit arrangement arranged on the it to melt and solidify the solder balls by heating and cooling respectively in order to bond and electrically connect the resonator body and the laminated circuit arrangement.
Then, since the open-circuit ends or edges of the through holes are used for positioning the solder balls, the bonding and the electric connection of the resonator body and the laminated circuit arrangement can be realized simply by electrically connecting the respective open-circuit ends or edges of the through holes and the corresponding connection terminals on the laminated circuit arrangement without any additional operation.
Alternatively, solder balls may be arranged on the connection terminals of the laminated circuit arrangement and the resonator body is placed in a holding hole of a jig with its the open-circuit end surface directed downward to melt and solidify the solder balls by heating and cooling respectively in order to bond and electrically connect the resonator body and the laminated circuit arrangement.
The length of a resonator should be defined as a function of the wavelength corresponding to the frequency to be used with it. Therefore, in case the present invention is to be applied to a dielectric duplexer device, the first filter section and the second filter section arranged in the resonator body may have to show different lengths to consequently give rise to a step at the end opposite to the end to which the laminated circuit arrangement is bonded. With such a resonator body, the laminated circuit
Achiha Hikaru
Kawase Hirotsugu
Larson & Taylor PLC
NGK Spark Plug Co. Ltd.
Pascal Robert
Summons Barbara
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