JP2556166B2 - Non-reciprocal circuit element - Google Patents

Description

The present invention relates to a non-reciprocal circuit device such as a circulator and an isolator used as a microwave band high frequency component, and particularly to reducing the number of components and the number of assembling steps to reduce the cost. The present invention relates to a structure that can reduce the size and realize the miniaturization and weight reduction of parts.

[Conventional technology]

Generally, circulators and isolators have a function of causing almost no attenuation in the signal transmission direction and increasing attenuation in the opposite direction.
It is used in the transmission circuit of mobile communication devices such as car phones. As such an isolator, there is a conventional one having a structure shown in FIG. In this isolator 40, a ferrite assembly 44, in which a pair of ferrites 43, 43 are opposed to a plurality of central conductors 42, is arranged in a magnetic metal case 41, and the assembly 44 is provided on the inner surface with a matching circuit. Central holes 45a, 45a of a pair of dielectric substrates 45, 45 on which capacitor electrodes for use are formed
A pair of permanent magnets 47, 47, which are located inside, are brought into contact with the ground electrode formed on the outer surface of each dielectric substrate 45 via shield plates 46, 46, respectively. The ferrite assembly 44 is formed by stacking three pairs of reticulated center conductors 42 made of, for example, copper plates in an electrically insulated state with an insulating sheet interposed therebetween, and intersecting them at intervals of 120 degrees. It is sandwiched between ferrites 43. Then, one end of a strip-shaped input / output terminal 48 embedded in a rectangular frame-shaped resin block 49 arranged along the inner peripheral edge of the case 41 is connected to the external lead-out portion 42a of each central conductor 42. The other end of each terminal 48 projects outward from the opening 41a of the case 41.

Here, when the above isolator or circulator is used in, for example, a mobile phone, there is a demand for cost reduction of components, and further miniaturization and weight reduction of components are required due to its application.

[Problems to be solved by the invention]

However, the conventional isolator described above has a problem that it cannot sufficiently meet the demand for cost reduction due to its structure, and that there is a limit to downsizing and weight saving.

That is, the assembly work of the above-mentioned conventional ferrite assembly is
Since it is necessary to insert the insulating sheet between the center conductors while alternately intersecting the center conductors, and to insert the assembly into the case while positioning it, the number of parts and Assembly man-hours increase, and the cost rises accordingly.

Also, since a metal case is used, it is necessary to set a large case to open a space between the case and the circuit element in order to avoid a short circuit due to contact with each circuit element. Upsizing. Further, it is difficult to reduce the weight by the weight of the metal case.

An object of the present invention is to provide a non-reciprocal circuit device in which the number of parts and the number of assembling steps can be reduced to reduce the cost and the size and weight of the parts can be reduced. It is an object.

[Means for solving problems]

According to the first aspect of the present invention, a circuit element body having an electric circuit function is disposed in a case, including a central conductor and a matching circuit arranged in a cross shape in an electrically insulated state, and a ferrite is opposed to the central conductor. In the non-reciprocal circuit element adapted to apply a DC magnetic field, the case is formed of an insulating resin, and the case is covered with an electrode film that constitutes at least a part of the circuit element body. I am trying.

A second aspect of the present invention is an invention in which a substrate portion is integrally formed on the case and a central conductor is formed on the substrate portion by coating, and a part of the central conductor is formed on one main surface of the substrate portion. In addition to forming the coating, the remaining main conductor is coated on the other main surface, and the central conductors are connected to each other by through-hole electrodes penetrating the substrate portion.

In the present invention, the "electrode film that constitutes at least a part of the circuit element body" is an "electrode film that influences the electric circuit function such as the attenuation characteristics of the nonreciprocal circuit element", for example, a central conductor, a matching circuit, Other means an electrode film that constitutes the additional circuit itself, for example, "a connection electrode film for connecting the central conductor that constitutes a part of the circuit element body to an external circuit".
Is not included.

Here, as a method for forming the central conductor on the substrate portion, a photo-etching method for forming an electrode film on both main surfaces of the substrate portion and removing an unnecessary portion of the electrode film, or an electroless plating method is adopted. it can. For example, in the case of the electroless plating method, a resin material to which plating is attached and a resin material to which plating is not attached are used. Injection molding with a material, place the molded product in a mold having a shape corresponding to the remaining case and substrate portion, inject a resin material that does not adhere to the plating into the mold, and perform injection molding. A case is formed by two-step injection molding. After that, by subjecting the case to electroless plating, for example, the electrode film can be formed only on the central conductor portion.

[Action]

According to the non-reciprocal circuit device of the present invention, the case is formed of the insulating resin, and the substrate part is integrally formed in the case, and the electrode film forming the circuit device body is formed on the substrate part by coating. Therefore, the circuit element body such as the center conductor can be easily patterned by the electroless plating method or the photo etching method. The conventional center conductors are overlaid with the insulating sheet interposed, and the center conductors are inserted while positioning them in the case. It is possible to eliminate the difficult assembling work. Moreover, since the board portion is formed integrally with the case, the number of parts can be reduced as compared with the conventional ferrite assembly, the productivity can be improved and the cost can be reduced, and the cost reduction can be met.

Further, since the case is insulative, it does not cause a short circuit even if it comes into contact with each circuit element, so that the short circuit preventing gap that has been conventionally required can be omitted, and the size can be reduced accordingly. Furthermore, since the resin case of the present invention can be made lighter than the metal case, the overall weight can be reduced accordingly.

〔Example〕

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

1 to 6 are views for explaining a non-reciprocal circuit device according to an embodiment of the present invention. In the present embodiment, the case of application to a lumped constant type isolator will be described as an example.

In the figure, reference numeral 1 is a lumped constant isolator of the present embodiment. In this isolator 1, a pair of ferrites 4a and 4b are arranged in a box-shaped case 2 so as to come into contact with a central conductor 3 formed in the box-shaped case 2.
Copper ground plates 5 and 5 are arranged on the outer surfaces of a and 4b, and permanent magnets 6 and 6 are arranged on the outer surfaces of the ground plates 5 and 5, respectively, and a DC magnetic field is applied to the central conductor 3 by the permanent magnets 6. Is configured to be applied. Further, a U-shaped metal yoke 7 made of a magnetic material is mounted on the case 2, and the yoke 7 closes the upper and lower openings of the case 2, thereby forming a magnetic closed circuit. . A recess 7a is formed in the metal yoke 7 so as to prevent a short circuit with a terminal portion described later.

The case 2 is made of an insulating resin and has a rectangular box shape including the first to fourth side walls 2a to 2d. In addition, a board portion 2e is provided at the center of the case 2.
Is integrally formed, and the inside of the case 2 is divided into an upper portion and a lower portion by the substrate portion 2e. A terminal portion 8 and a ground portion 9 are integrally formed at both ends of the lower ends of the outer surfaces of the second and fourth side walls 2b and 2d of the case 2, respectively. Further, the first portion of the lower portion of the substrate portion 2e,
A corner portion 10 extending to the lower surface of the case 2 is formed to bulge at a corner portion between the side wall 2a and the adjacent second and fourth side walls 2b and 2d.
A through hole 11 extending in the vertical direction is formed in the corner portion 10. The upper end of the through hole 11 penetrates the upper surface of the substrate portion 2e, and the lower end penetrates the lower surface of the terminal portion 8.

Further, conical protrusions 12 for contacting and positioning the outer peripheral surfaces of the ferrites 4a and 4b are formed at three positions on the upper surface and the lower surface of the substrate portion 2e so as to project every 120 degrees. The protrusion height of the protrusion 12 is set to be substantially the same as the thickness of the ferrites 4a and 4b. Further, an earth piece 5a projectingly formed on the outer peripheral portion of the earth plate 5 is in contact with the upper surface of the convex portion 12. Further, a through hole 13 is formed through the axial center of the convex portion 12.

On the upper surface and the lower surface of the substrate portion 2e, a part and the remaining portion of the center conductor 3 which is divided into two are formed. The center conductor 3 is point-symmetrical with a pair of parallel conductor pieces 3a (a part of the center conductor) on the upper surface of the substrate portion 2e and the other conductor piece 3b (the rest of the center conductor) on the lower surface. A structure in which the inner ends of the conductor pieces 3a, 3b are opposed to each other with the substrate portion 2e sandwiched therebetween, and the respective inner ends are connected by a through-hole electrode 14 formed through the substrate portion 2e. Has become. As a result, the respective center conductors 3 are 120
It has a structure that crosses in an electrically insulated state every time,
The ferrites 4a and 4b face the intersecting portions on both sides.

Also, the lower ferrite 4b on the lower surface of the substrate 2e is
A ground electrode film 16 is formed on the portion other than the abutting part of each of the projections 12 and the outer surface of each convex portion 12, and the outer end portion of each conductor piece 3b on the lower surface is connected to the ground electrode film 16. There is. Further, the ground electrode 16 extends through the through hole 13 of the convex portion 12 to the upper surface of the convex portion 12 on the upper surface side of the substrate portion 2e, whereby the ground electrode 16 is connected to the ground plate 5. Further, three matching circuit capacitor electrode films 17a to 17c are formed on the upper surface of the substrate portion 2e.
The outer end portions of the conductor pieces 3a on the upper surface are connected to ˜17c. Furthermore, a chip resistor 18 is connected to the one capacitor electrode film 17a, and the resistor 18 is connected to the ground electrode film 16 via a through hole electrode 19.

Further, the outer surface of each terminal portion 8 and the through hole
An input / output electrode film 20 is formed on the inner peripheral surface of the electrode 11, and the electrode film 20 is connected to the two capacitor electrode films 17b and 17c. Further, a ground electrode film 22 is formed on the outer surface of each ground portion 9, and the ground electrode film 22 passes through the inner surfaces of the second and fourth side walls 2b and 2d of the case 2 and the lower surface of the substrate portion 2e. Is connected to the ground electrode film 16 of.

Here, the central conductor 3, the capacitor electrode film 17a ~ 17c,
The input and output electrode films 20 and the ground electrode films 16 and 22 are formed by selectively performing electroless plating. For example, the following method can be adopted to perform the selective plating. First, in the case 2, the board portion 2e,
Portions of the terminal portions 8, the ground portion 9 and the through holes 11 and 13 corresponding to the electrode films are formed by injection with a resin material to which plating is attached. Next, this molded product is placed in a mold corresponding to the overall shape of the case 2, and a resin material to which plating does not adhere is injected into the mold. The case 2 is formed by such two-step injection molding. Thereafter, the case 2 is subjected to electroless plating to form the respective electrode films at the respective necessary portions.

 Next, the function and effect of this embodiment will be described.

The isolator 1 of the present embodiment has a function of blocking the reverse flow of signals, and is an essential component for mobile communication devices such as mobile phones and car phones.

Further, according to the present embodiment, the case 2 is formed of an insulating resin, and the board portion 2e is integrally formed in the case 2, and the center conductor 3 and the matching circuit capacitor electrode are formed in the board portion 2e.
Since the electrode films constituting the circuit element body such as 17a to 17c are formed, the conventional assembly work of stacking the respective central conductors with the insulating sheet interposed therebetween and inserting them while positioning them in the case can be eliminated. Further, in this embodiment, since the terminal portion 8 and the ground portion 9 are integrally formed on the case 2 and connected to a predetermined portion by the electrode film, the conventional terminal block can be omitted. As a result, the number of parts and the number of assembling steps can be reduced, and the cost can be reduced, as compared with the conventional ferrite assembly or terminal block.

Further, since the case 2 is made of an insulating resin, it does not cause a short circuit even when it comes into contact with each circuit element such as the ground plate 5, and the conventional terminal block can be eliminated. The space for use can be omitted, and the parts can be downsized accordingly. Furthermore, since the case 2 can be made lighter in weight than the conventional metal case, the case 2 can be made lighter.

Furthermore, according to the present embodiment, since each central conductor 3, the input / output electrode film 20, the ground electrode film 16 and the like are formed by electroless plating, it is possible to easily form a pattern. And in this case,
Good electrical conductivity can be obtained, and the heat conduction can be lower than that of conventional metal terminals.This is because it is difficult for solder heat to be transmitted to each component element when reflow soldering the above component elements. It is possible to avoid adverse effects on the quality and improve reliability of quality.

In addition, the capacitor electrode films 17a-1
Since 7c is formed, the dimensional accuracy can be improved, and an accurate capacitance value can be obtained accordingly. This can solve the problem that the conventional capacitor electrode film is thick film printed on the dielectric substrate and is baked, so that the electrode film is easily displaced.

Furthermore, in the present embodiment, since the component elements such as the board portion 2e and the terminal portion 8 are integrally formed on the case 2, the number of soldering points can be significantly reduced as compared with the conventional structure. The quality can be improved.

In the above embodiment, the central conductor 3, the capacitor electrode films 17a to 17c, the ground electrode 16 and the like which form the circuit element body are all formed on the substrate 2e by coating, but in the present invention, at least a part of the circuit element body is formed. It is also possible to cover the substrate portion and form the remaining portion on the side wall, or it is possible to form the entire circuit element on the side wall of the case.

In the above embodiment, the case where the resin material to which the plating adheres and the resin material to which the plating does not adhere is used, the case is formed by the two-step injection molding, and the case is subjected to the electroless plating treatment has been described as an example. The method of forming the electrode film of the present invention is not necessarily limited to this, and the electrode film may be formed by, for example, a photoetching method.

Further, in the above-described embodiment, the case where two ferrites and two permanent magnets are used has been described as an example. However, in the present invention, when the required characteristics are not so high, only one may be used.

Furthermore, although the lumped-constant type isolator has been described as an example in the above embodiment, the present invention can be applied not only to the distributed-constant type isolator but also to the circulator. This can be realized by removing the connected resistor and connecting the terminal portion to the electrode film.

〔The invention's effect〕

As described above, according to the nonreciprocal circuit device of the present invention,
Since the case is formed of the insulating resin and the electrode film forming at least a part of the circuit element body is formed in the case, the conventional laborious assembly work can be eliminated and the number of parts can be reduced. As a result, the productivity can be improved and the cost can be reduced, and the parts can be made smaller and lighter.

[Brief description of drawings]

1 to 6 are views for explaining an isolator according to an embodiment of the present invention. FIG. 1 is an exploded perspective view of the isolator, FIG. 2 is a plan view of a case, and FIG. Bottom view, FIG. 4 is a plan view of the isolator, FIG. 5 is a sectional view taken along line VV of FIG. 4, FIG. 6 is a sectional view taken along line VI-VI of FIG. 4, and FIG. It is sectional drawing shown. In the figure, 1 is an isolator (non-reciprocal circuit element), 2
Is a case, 2e is a substrate, 3,17a to 17c, 16 are central conductors, capacitor electrode films, earth electrode films (electrode films that compose the circuit element body), 4a and 4b are ferrites, and 6 is a permanent magnet. .

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takashi Kawanami 2-26-10 Tenjin, Nagaokakyo City, Kyoto Prefecture Murata Manufacturing Co., Ltd. (56) References JP-A-3-252202 (JP, A) 3-84604 (JP, U)

Claims (2)

(57) [Claims] 1. A case is provided with a circuit element body having an electric circuit function, which includes a central conductor and a matching circuit arranged in an electrically insulated state in a crossed manner, and a ferrite is opposed to the central conductor. In the non-reciprocal circuit element configured to apply a DC magnetic field together with the case, the case is formed of an insulating resin, and the case is covered with an electrode film forming at least a part of the circuit element body. Characteristic non-reciprocal circuit device. 2. A substrate part is integrally formed on the case, and one main surface of the substrate part is covered with a part of the central conductor and the other main surface is covered with a remaining part of the central conductor. The non-reciprocal circuit device according to claim 1, wherein the respective central conductors are connected to each other by through-hole electrodes penetrating the substrate portion.