Abstract:
An inductor array used for an electronic circuit. The inductor array has two magnetic sections, each of which contains a plurality of inductor elements, and an insulating section which is disposed between the magnetic sections. The insulating section inhibits crosstalk between the inductor elements in one magnetic section and those in the other magnetic section. Further, by making the insulating section of a dielectric material and providing capacitor elements in the insulating section, an LC composite array can be obtained.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an inductor device to be employed in an electronic circuit, and more particularly to an inductor array comprising a plurality of inductor elements. 
     2. Description of Prior Art 
     In an inductor array which has a plurality of inductor elements in a magnetic body, crosstalk between adjacent inductor elements caused by their mutual magnetic coupling has been a big problem. For downsizing of the inductor array, external electrodes and inductor elements have to be arranged at a small pitch, and accordingly, the crosstalk occurring among the inductor elements becomes larger. Also, for an increase in the impedance, a magnetic body with a higher magnetic permeability has to be used, and thereby, the crosstalk occurring among the inductor elements becomes larger. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide an inductor array which has such a structure as to inhibit crosstalk between adjacent inductor elements. 
     In order to attain the object, an inductor array according to the present invention comprises a first magnetic section containing a plurality of inductor elements, a second magnetic section containing a plurality of inductor elements, and an insulating section which is disposed between the first and second magnetic sections to inhibit crosstalk between the inductor elements in the first magnetic section and the inductor elements in the second magnetic section. 
     In the structure, since the insulating section with a low magnetic permeability is between the magnetic sections, the influence of magnetic fluxes which are generated by the inductor elements in each magnetic section on the other magnetic section is weakened by the insulating section, and the magnetic coupling between the inductor elements in the first magnetic section and those in the second magnetic section can be weakened. 
     Further, by making the insulating section of a dielectric material and providing capacitor elements in the insulating section, an LC composite array used as a noise filter or the like can be obtained. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     This and other objects and features of the present invention will be apparent from the following description with reference to the accompanying drawings, in which: 
     FIGS. 1, 2, 3, 4, 5, 6, 7, 8 and 9 are plan views of base sheets for an inductor array which is a first embodiment of the present invention; 
     FIG. 10 is a perspective view of the inductor array of the first embodiment; 
     FIG. 11 is a sectional view of the inductor array, taken along a line XI--XI indicated in FIG. 10; 
     FIG. 12 is an electrical equivalent circuit of the inductor array shown in FIG. 10; 
     FIG. 13, 14, 15 and 16 are plan views of base sheets for an inductor array which is a second embodiment; 
     FIG. 17 is a perspective view of the inductor array of the second embodiment; 
     FIG. 18 is a sectional view of the inductor array, taken along a line XVIII--XVIII indicated in FIG. 17; 
     FIG. 19 is a sectional view of the inductor array, taken along a line XIX--XIX indicated in FIG. 17; and 
     FIG. 20 is an electrical equivalent circuit of the inductor array shown in FIG. 17. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Preferred embodiments of the present invention are described with reference to the accompanying drawings. In the embodiments, the same members and sections are provided with the same reference symbols. 
     First Embodiment: FIGS. 1-12 
     FIGS. 1 through 9 show base sheets which form an inductor array of a first embodiment. FIG. 1 shows a magnetic sheet 1a with no conductors thereon, and this magnetic sheet 1a serves as a protection sheet. FIG. 2 shows a magnetic sheet 1b with two identical coil conductors 2 on one side. One end 2a of each conductor 2 reaches an edge of the magnetic sheet 1b, and the other end becomes a via hole 11. FIG. 3 shows a magnetic sheet 1c with two identical coil conductors 3 on one side. One end of each conductor 3 becomes a via hole 12, and the other end becomes a contact pad 3a. FIG. 4 shows a magnetic sheet 1d with two identical coil conductors 4. One end of each conductor 4 becomes a contact pad 4a, and the other end 4b reaches an edge of the magnetic sheet 1d. 
     FIG. 5 shows an insulating sheet 1e with no conductors thereon. FIG. 6 shows a magnetic sheet 1f with no conductors thereon. FIG. 7 shows a magnetic sheet 1g with two identical coil conductors 6 on one side. One end 6a of each conductor 6 reaches an edge of the magnetic sheet 1g, and the other end becomes a via hole 13. FIG. 8 shows a magnetic sheet 1h with two identical coil conductors 7 on one side. One end of each conductor 7 becomes a via hole 14, and the other end becomes a contact pad 7a. FIG. 9 shows a magnetic sheet 1i with two identical coil conductors 8 on one side. One end of each conductor 8 becomes a contact pad 8a, and the other end 8b reaches an edge of the magnetic sheet 1i. 
     The sheets 1a through 1i are laminated such that the sheet 1i is at the bottom, that the sheet 1g is placed on the sheet 1i, that the sheet 1h is placed on the sheet 1i,-- and that the sheet 1a is at the top. These laminated sheets 1a through 1i are compression-bonded and sintered. Thus, an inductor array 15 as shown by FIG. 10 and 11 is fabricated. The inductor array 15 is provided with input electrodes 16 on the front edge and with output electrode 17 on the rear edge. The coil conductors 2 and 6 are connected with the output electrodes, and the coil conductors 4 and 8 are connected with the input electrodes 16. 
     In the laminate structure, the insulating sheet 1e is between an upper magnetic section composed of the magnetic sheets 1a through 1d and a lower magnetic section composed of the magnetic sheets if through 1i. In the upper magnetic section, the coil conductors 2, 3 and 4 are serially connected through the via holes 11 and 12, and thus, inductor elements 21a are formed. In the lower magnetic section, the coil conductors 6, 7 and 8 are serially connected through the via holes 13 and 14, and thus, inductor elements 21b are formed. The inductor elements 21a and 21b are staggered in the direction of the thickness of the inductor array 15 with the insulating sheet 1e in-between. FIG. 12 shows the electric equivalent circuit of the inductor array 15. 
     In the inductor array 15 of the above structure, since the insulating sheet 1e with a low magnetic permeability is between adjacent inductor elements 21a and 21b, magnetic fluxes generated by the inductor elements 21a and 21b are weakened by the insulating sheet 1e, and the magnetic coupling therebetween can be weakened. Consequently, in the inductor array 15, the crosstalk between adjacent inductor elements 21a and 21b can be inhibited. 
     Second Embodiment; FIGS. 13 through 20 
     A second embodiment is an inductor array which has an insulting section made of a dielectric material and capacitor elements in the insulating section. The second embodiment has the same magnetic sections as the first embodiment, and the description of the magnetic sections is omitted. 
     FIGS. 13 through 16 show base sheets which form the insulating section. FIG. 13 shows a dielectric sheet 30a with no conductors thereon. FIG. 14 shows a dielectric sheet 30b with an internal grounding conductor 31 on one side. The right end 31b and the left end 31a of the internal grounding conductor 31 reach right and left edges of the dielectric sheet 30b. A dielectric sheet 30d shown by FIG. 16 has an internal grounding conductor 31 of the same shape. FIG. 15 shows a dielectric sheet 30c with internal signal conductors 32 and 33 on one side. The internal signal conductors 32 and 33 are opposite each other. 
     The sheets 30a through 30d are laminated such that the sheet 30d is at the bottom, that the sheet 30c and then the sheet 30b are placed on the sheet 30d and that the sheet 30a is at the top. Thus, a dielectric section is formed. Then, the dielectric section is placed between the magnetic sections, and these sections are compression-bonded and sintered. In this way, an inductor array 40 as shown by FIGS. 17 through 19 are fabricated. On the right and left edges of the inductor array 40, external grounding electrodes 42 and 41 are provided. On the front edge and on the rear edge of the inductor array 40, input electrodes 43 and output electrode 44 are provided respectively. Each of the inductor elements 21a or 21b is in contact with the input electrode 43 at one end and is in contact with the output electrode 44 at the other end. The internal signal electrodes 32 are connected with the input electrode 43 and the internal signal electrodes 33 are connected with the output electrode 44. Each of the internal grounding conductors 31 is in contact with the external grounding electrodes 42 and 41 at the right and left ends. 
     In the laminate structure, the internal signal conductors 32 and the internal grounding conductors 31 form capacitors. The inductor elements 21a formed in the upper magnetic section and the inductor elements 21b formed in the lower magnetic section are separated by the insulating section composed of the dielectric sheets 30a through 30d. FIG. 20 shows the electric equivalent circuit of the inductor array 40. The inductor array 40 contains four π type LC elements. 
     The inductor array 40 of the above structure has the same action and effect as described in connection with the inductor array 15 of the first embodiment. Moreover, the inductor array 40 is an LC composite array which can be used as a noise filter or the like. 
     Other Embodiments 
     Although the inductor elements of the above embodiments are of a spiral type, they may be other types such as a linear type. 
     Both of the above embodiments have a single insulating section. However, an inductor array may have two or more insulating sections and have more layers. 
     The inductor array of the second embodiment contains π type elements. However, the inductor array can be made so as to contain L type or T type elements. Also, the inductor array can be made so as to contain any number of elements. 
     In the above embodiments, the inductor elements in the respective magnetic sections are positioned such that the inductor elements in the upper magnetic section and those in the lower magnetic section are staggered in the direction of the thickness of the inductor array. However, this positioning is not always necessary, and the inductor elements may be positioned such that the inductor elements in the upper magnetic section will be right above those in the lower magnetic section with the insulating section in-between. 
     Although the present invention has been described connection with the preferred embodiments above, it is to be noted that various changes and modifications are possible to those who are skilled in the art. Such changes and modifications are to be understood as being within the scope of the present invention.