Patent Publication Number: US-2011050380-A1

Title: Coil apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority from Japanese Patent Application No. 2009-194205 filed on Aug. 25, 2009, the entire subject matter of which is incorporated herein by reference. 
     BACKGROUND 
     1. Technical Field 
     The present invention relates to a coil apparatus for use in a transformer, an inductor or the like. 
     2. Description of The Related Art 
     In order to make a transformer, an inductor, etc., smaller and thinner, a coil apparatus provided in those devices is getting smaller and thinner. In such a coil apparatus, a coil pattern made from a conductive material, such as a copper thin film etc., is formed into spiral shape around a hole for inserting a core on an insulative substrate. In such case, it has been known that eddy current losses are came up in the coil pattern cause to an effect of leakage flux from the core. (see e.g. JP-A-H08-203736). 
     In the coil apparatus including the core that disclosed in JP-A-H08-203736, a plurality of slits, which extends along a current flowing direction in the spiral conductive pattern on the insulative substrate, is provided in a region where a proximity effect is intensely came up by leakage flux. The slit serves to divide a path of large eddy current caused by leakage flux to prevent large eddy current being generated. The slit also serves to increase a surface area of the coil pattern so as to reduce concentration of current distribution caused by a synergistic action of a skin effect and the proximity effect by eddy current in the coil pattern. The conduction loss in the coil pattern is reduced by the slit provided in the coil pattern. 
     However, if a slit extending along a current direction is provided in the whole or a part of a coil pattern and is divided into a plurality of wiring patterns (conductive patterns), an inner wiring pattern and an outer wiring pattern are formed and the lengths of the respective wiring patterns become different, so that resistance of the inner wiring pattern becomes lower than that of the outer wiring pattern. Thus, a problem arises that currents do not flow through the respective wiring patterns in the same quantity and greater current flows through the inner wiring pattern. 
     SUMMARY 
     Therefore, the coil apparatus of the invention is objected to balance current flowing through the respective wiring patterns, even if the whole or a part of a coil pattern is divided into a plurality of wiring patterns by a slit extending along current direction 
     In the invention, A coil apparatus comprising: a core-insertion hole for inserting a core; a plurality of wiring layers including a first wiring layer and a second wiring layer; a coil pattern, which is formed on each of the plurality of wiring layers into a spiral shape around the core-insertion hole, wherein the coil patterns on the each wiring layers is connected in series and integrated so as to form a single coil formed of laminated wiring layers; and a slit, which extends along a current direction, and which divides at least part of each of the coil patterns formed on each of the respective the first wiring layer and the second wiring layer into a plurality of wiring patterns, wherein each of the plurality wiring patterns includes an outermost wiring pattern and an innermost wiring pattern, wherein the second wiring layer is laminated just below the first wiring layer, wherein an outermost wiring pattern on the first wiring layer is connected to an innermost wiring pattern on the second wiring layer, and wherein an innermost wiring pattern on the first wiring layer is connected to an outermost wiring pattern on the second wiring layer. 
     According to the invention, a coil apparatus capable of balancing respective currents flowing through a plurality of divided wiring patterns is provided. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1A  is a view showing an array configuration of a wiring pattern formed in each wiring layers in a coil apparatus of a first embodiment, and  FIG. 1B  is a view showing an connection configuration of a wiring pattern formed in each wiring layers in a coil apparatus of the first embodiment; 
         FIG. 2A  is a view showing an array configuration of a wiring pattern formed in each wiring layers in a coil apparatus of a second embodiment, and  FIG. 2B  is a view showing an connection configuration of a wiring pattern formed in each wiring layers in a coil apparatus of the second embodiment; and 
         FIG. 3A  is a view showing an array configuration of a wiring pattern formed in each wiring layers in a coil apparatus of a third embodiment, and  FIG. 3B  is a view showing an connection configuration of a wiring pattern formed in each wiring layers in a coil apparatus of the third embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Hereinafter, a coil apparatus according embodiments will be described in detail with reference to the drawings. 
     First Embodiment  
       FIG. 1A  is a view showing an array configuration of a wiring pattern formed in each wiring layers in a coil apparatus of a first embodiment, and  FIG. 1B  is a view showing an connection configuration of a wiring pattern formed in each wiring layers in a coil apparatus of the first embodiment. As shown in  FIGS. 1A and 1B , the coil apparatus of the first embodiment is configured so that: a coil pattern is formed into spiral shape around a core-insertion hole H 1  for inserting a core, on each wiring layers N 1  to N 4  including a first wiring layer N 1 , a second wiring layer N 2 , a third wiring layer N 3  and a fourth wiring layer N 4 ; the each wiring layer N 1  to N 4  are laminated in the order of N 1  (an uppermost wiring layer), N 2 , N 3 , N 4  (a lowest wiring layer) as enumerated from the topside; the coil patterns formed on each wiring layers N 1  to N 4  are serially connected through a via-hole (which is called as a conduction hole to electrically connect the wiring layers each other); the coil patterns formed on each wiring layers N 1  to N 4  are combined and make up a single coil. That is, the each wiring layer N 1  to N 4  is configured so that: the coil pattern made from a conductive material such as a copper thin film, etc., is formed into spiral shape around a core-insertion hole H 1  for inserting a core, on an insulative substrate; via-hole is formed on one or both ends of the coil pattern (one or both ends of the divided each wiring patterns). 
     The coil pattern  10  formed on the first wiring layer N 1  is divided into an outermost wiring pattern  11  and an innermost wiring pattern  12  by a slit S 1  extending along a current direction so as to have the same widths. The slit S 1  is formed in the whole of the coil pattern  10  from one end to another end. One-side ends of the wiring patterns  11 ,  12  (one end of the coil pattern  10 ) are connected to a pad C 1  and become an end of a coil (a single coil) integrated with the pad C 1 . Another-side ends of the wiring patterns  11 ,  12  (another end of the coil pattern  10 ) have via-holes  15 ,  16 , respectively, to serially connect with respective one-side ends of wiring patterns  21 ,  22  (one end of a coil pattern  20 ) formed on the second wiring layer N 2  which will be described later. 
     The coil pattern  20  formed on the second wiring layer N 2  is divided into an innermost wiring pattern  21  and an outermost wiring pattern  22  by a slit S 2  extending along a current direction so as to have the same widths. The slit S 2  is formed in the whole of the coil pattern  20  from one end to another end. One-side ends of the wiring patterns  21 ,  22  have via-holes  23 ,  24 , respectively, to serially connect with respective another-side ends of the wiring patterns  11 ,  12  formed on the first wiring layer N 1 . Another-side ends of the wiring patterns  21 ,  22  (another end of the coil pattern  20 ) have via-holes  25 ,  26 , respectively, to serially connect with respective one-side ends of wiring patterns  31 ,  32  (an end of a coil pattern  30 ) formed on the third wiring layer N 3  which will be described later. 
     The coil pattern  30  formed on the third wiring layer N 3  is divided into an outermost wiring pattern  31  and an innermost wiring pattern  32  by a slit S 3  extending along a current direction so as to have the same widths. The slit S 3  is formed in the whole of the coil pattern  30  from one end to another end. One-side ends of the wiring patterns  31 ,  32  have via-holes  33 ,  34 , respectively, to serially connect with respective another-side ends of the wiring patterns  21 ,  22  formed on the second wiring layer N 2 . Another-side ends of the wiring patterns  31 ,  32  (another end of the coil pattern  30 ) have via-holes  35 ,  36 , respectively, to serially connect with respective one-side ends of wiring patterns  41 ,  42  (an end of a coil pattern  40 ) formed on the fourth wiring layer N 4  which will be described later. 
     The coil pattern  40  formed on the fourth wiring layer N 4  is divided into an innermost wiring pattern  41  and an outermost wiring pattern  42  by a slit S 4  extending along a current direction so as to have the same widths,. The slit S 4  is formed in the whole of the coil pattern  40  from one end to another end. One-side ends of the wiring patterns  41 ,  42  have via-holes  43 ,  44 , respectively, to serially connect with respective another-side ends of the wiring patterns  31 ,  32  formed on the third wiring layer N 3 . Another-side ends of the wiring patterns  41 ,  42  (another end of the coil pattern  40 ) are connected to a pad C 2  and become another end of a coil (a single coil) integrated with the pad C 2 . 
     The wiring patterns  11 ,  21  are serially connected by via-holes  15 ,  23 , the wiring patterns  21 ,  31  are serially connected by via-holes  25 ,  33 , and the wiring patterns  31 ,  41  are serially connected to each other by via-holes  35 ,  43 . Thus, the wiring patterns  11 ,  21 ,  31 , 41  are serially connected in the order of an outermost wiring pattern in the first wiring layer N 1 , an innermost wiring pattern in the second wiring layer N 2 , an outermost wiring pattern in the third wiring layer N 3 , and an innermost wiring pattern in the fourth wiring layer N 4  as enumerated. 
     Similarly, the wiring patterns  12 ,  22  are serially connected by via-holes  16 ,  24 , the wiring patterns  22 ,  32  are serially connected by via-holes  26 ,  34 , and the wiring patterns  32 ,  42  are serially connected by via-holes  36 ,  44 . Thus, the wiring patterns  12 ,  22 ,  32 ,  42  are serially connected in the order of an innermost wiring pattern in the first wiring layer N 1 , an outermost wiring pattern in the second wiring layer N 2 , an innermost wiring pattern in the third wiring layer N 3 , and an outermost wiring pattern in the fourth wiring layer N 4  as enumerated. 
     Therefore, since the length L 101  of the serially connected wiring patterns  11 ,  21 ,  31 ,  41  becomes equal to the length L 102  of the serially connected wiring patterns  12 ,  22 ,  32 ,  42 , so that resistance values thereof become equal to each other. Therefore, respective currents flowing through the respective wiring patterns divided into two sections in the wiring layers can be balanced. 
     That is, current flowing into one end C 1  of the coil (single coil) formed by combining the four wiring layers is equally divided into the serially connected wiring patterns  11 ,  21 ,  31 ,  41  and the serially connected wiring patterns  12 ,  22 ,  32 ,  42 . And then, the current flows out through another end C 2 . 
     According to the coil apparatus of the first embodiment, the whole or a part of the wiring patterns that are formed on the first wiring layer N 1  and the second wiring layer N 2  placed directly below the first wiring layer N 1  is divided into wiring patterns  11 ,  12  and wiring patterns  21 ,  22  by the slits S 1 , S 2 , respectively. Since the outermost wiring pattern  11  in the first wiring layer N 1  is connected to the innermost wiring pattern  21  in the second wiring layer N 2 , and the innermost wiring pattern  12  in the first wiring layer N 1  is connected to the outermost wiring pattern  22  in the second wiring layer N 2 , respective currents flowing through the wiring patterns  11 ,  12  and the wiring patterns  21 ,  22  divided into two sections can be balanced. 
     In addition, the whole or a part of the wiring patterns that are formed on the fourth wiring layer N 4  and the third wiring layer N 3  placed directly above the fourth wiring layer N 4  is divided into wiring patterns  41 ,  42  and wiring patterns  31 ,  32  by the slits S 4 , S 3 , respectively. Since the outermost wiring pattern  31  in the third wiring layer N 3  is connected to the innermost wiring pattern  41  in the fourth wiring layer N 4 , and the innermost wiring pattern  32  in the third wiring layer N 3  is connected to the outermost wiring pattern  42  in the fourth wiring layer N 4 , respective currents flowing through the wiring patterns  31 ,  32  and the wiring patterns  41 ,  42  divided into two sections can be balanced. 
     Second Embodiment 
       FIG. 2A  is a view showing an array configuration of a wiring pattern formed in each wiring layers in a coil apparatus of a second embodiment, and  FIG. 2B  is a view showing an connection configuration of a wiring pattern formed in each wiring layers in a coil apparatus of the second embodiment.  FIGS. 2A and 2B  are different from the configuration of the first embodiment shown in  FIGS. 1A and 1B . In the  FIGS. 1A and 1B , the slit is provided along a current direction in the whole of the coil pattern from one end to another end, on the other hand, in case of the second embodiment, a slit is provided along a current direction in a part of a coil pattern in a region near a core-insertion hole (a region susceptible to leakage flux that leaks from a core). 
     At a spiraled wiring portion near a core-insertion hole H 1   a , a coil pattern  10   a  formed on a first wiring layer N 1   a  is divided into an outermost wiring pattern  11   a  and an innermost wiring pattern  12   a,  which have the same widths, by a slit S 1   a  extending along a current direction. One-side ends of the wiring patterns  11   a  and  12   a  become another-side ends of an undivided portion  101   a  of the coil pattern  10   a,  and one end of the undivided portion  101   a  of the coil pattern  10   a  (one end of the coil pattern  10   a ) is connected to a pad C 1  a and become an end of a coil (a single coil) integrated with the pad C 1   a . Another-side ends of the wiring patterns  11   a  and  12   a  (another end of the coil pattern  10   a ) have via-holes  15   a,    16   a,  respectively, to serially connect with respective one-side ends of wiring patterns  21   a,    22   a  (an end of a coil pattern  20   a ) formed on a second wiring layer N 2   a  which will be described later. 
     At a spiraled wiring portion near a core-insertion hole H 1   a , the coil pattern  20   a  formed on a second wiring layer N 2   a  is divided into an innermost wiring pattern  21   a  and an outermost wiring pattern  22   a  by a slit S 2   a  extending along a current direction, so as to have the same widths. One-side ends of the wiring patterns  21   a  and  22   a  have via-holes  23   a,    24   a,  respectively, to serially connect with respective another-side ends of the wiring patterns  11   a,    12   a  formed on the first layer. Another-side ends of the wiring patterns  21   a,    22   a  become one end of an undivided portion  201   a  of the coil pattern  20   a , another end of the undivided portion  201   a  of the coil pattern  20   a  (another end of the coil pattern  20   a ) have a via-hole  25   a  to serially connect with one end of an undivided portion  301   a  of a coil pattern  30   a  formed on a third wiring layer N 3   a  to be described below. 
     At a spiraled wiring portion near a core-insertion hole H 1   a , the coil pattern  30   a  formed on the third wiring layer N 3   a  is divided, into an outermost wiring pattern  31   a  and an innermost wiring pattern  32   a  by a slit S 3   a  extending along a current direction so as to have the same widths. One-side ends of the wiring patterns  31   a,    32   a  become another end of an undivided portion  301   a  of the coil pattern  30   a,  and one end of the undivided portion  301   a  of the coil pattern  30   a  (one end of the coil pattern  30   a ) has a via-hole  33   a  to serially connect with another end of the undivided portion  201   a  of the coil pattern  20   a  (another end of the coil pattern  20   a ) formed on the second wiring layer N 2   a.  Another-side ends of the wiring patterns  31   a,    32   a  (another end of the coil pattern  30   a ) have via-holes  35   a,    36   a,  respectively, to respective serially connect with one-side ends of wiring patterns  41   a,    42   a  formed on a fourth wiring layer N 4   a  to be described below. 
     At a wiring portion near a core-insertion hole H 1   a , the coil pattern  40   a  formed on the fourth wiring layer N 4   a  is divided into an innermost wiring pattern  41   a  and an outermost wiring pattern  42   a  by a slit S 4   a  extending along a current direction as to have the same widths. One-side ends of the wiring patterns  41   a,    42   a  have via-holes  43   a,    44   a,  respectively, to serially connect with respective another-side ends of the wiring patterns  31   a,    32   a  formed on the third wiring layer N 3   a.  Another-side ends of the wiring patterns  41   a,    42   a  become one end of an undivided portion  401   a  of the coil pattern  40   a,  and another end of the undivided portion  401   a  of the coil pattern  40   a  (another end of the coil pattern  40   a ) is connected to a pad C 2   a  and becomes another end of a coil (a single coil) integrated with the pad C 2   a.    
     The wiring patterns  11   a ,  21   a  are serially connected to each other by the via-holes  15   a,    23   a,  the coil patterns  20   a,    30   a  are serially connected to each other by the via-holes  25   a,    33   a  , and the wiring patterns  31   a,    41   a  are serially connected to each other by the via-holes  35   a,    43   a.  Thus, the wiring patterns  11   a,    21   a  are serially connected in the order of an outermost wiring pattern in the first wiring layer N 1   a  and an innermost wiring pattern in the second wiring layer N 2   a.  The wiring patterns  31   a,    41   a  are serially connected in the order of an outermost wiring pattern in the third wiring layer N 3   a  and an innermost wiring pattern in the fourth wiring layer N 4   a.    
     Similarly, the wiring patterns  12   a,    22   a  are serially connected to each other by the via-holes  16   a,    24   a,  the coil patterns  20   a,    30   a  are serially connected to each other by the via-holes  25   a,    33   a,  and the wiring patterns  32   a,    42   a  are serially connected to each other by the via-holes  36   a,    44   a.  Thus, the wiring patterns  12   a,    22   a  are serially connected in the order of an innermost wiring pattern in the first wiring layer N 1   a  and an outermost wiring pattern in the second wiring layer N 2   a,  and the wiring patterns  32   a ,  42   a  are serially connected to each other at places in the order of an innermost wiring pattern in the third wiring layer N 3   a  and an outermost wiring pattern in the fourth wiring layer N 4   a.    
     Therefore, the length L 201  of the serially connected wiring patterns  11   a ,  21   a  becomes equal to the length L 202  of the serially connected wiring patterns  12   a,    22   a , so that resistance values thereof become equal to each other. In addition, the length L 203  of the serially connected wiring patterns  31   a,    41   a  becomes equal to the length 
     L 204  of the serially connected wiring patterns  32   a,    42   a,  so that resistance values thereof become equal to each other. Therefore, respective currents flowing through the respective wiring patterns divided into two sections in the wiring layers can be balanced. 
     That is, current flowing into one end C 1   a  of the coil (single coil) formed by combining the four wiring layers is equally divided into the serially connected wiring patterns  11   a ,  21   a  and the serially connected wiring patterns  12   a,    22   a  respectively, and similarly equally divided into the wiring patterns  31   a,    41   a  and the wiring patterns  32   a ,  42   a,  respectively. And then, the current flows out through another end C 2   a.    
     According to the coil apparatus of the second embodiment, the same effect as the first embodiment can be obtained. 
     Third Embodiment 
     In the first embodiment, the coil pattern formed on the respective wiring layers is divided into a plurality of sub-coil patterns. As a result, as the number of the wiring layers (the number of stacked layers) increases, the number of the via-holes also increases. When the number of the via-holes increases, a region where the wiring patterns can be formed may be reduced, so that the wiring length of the wiring pattern may become longer. 
     According to a third embodiment, a coil pattern in a surface-side wiring layer that is susceptible to leakage flux that leaks from a core is divided into a plurality of wiring patterns. A coil pattern in an intermediate wiring layer that is not susceptible to leakage flux that leaks from a core is not divided into sub-wiring patterns and is provided as one wiring pattern (single coil pattern). 
       FIG. 3A  is a view showing an array configuration of a wiring pattern formed in each wiring layers in a coil apparatus of a third embodiment, and  FIG. 3B  is a view showing an connection configuration of a wiring pattern formed in each wiring layers in a coil apparatus of the third embodiment. In  FIGS. 3A and 3B , parts identical to the first embodiment shown in  FIGS. 1A and 1B  are designated as the same reference signs as the first embodiment, and the description thereof will be omitted. The  FIGS. 3A and 3B  are different from the first embodiment of  FIGS. 1A and 1B . In the FIGS.  3 A and  3 B, two wiring layers are provided between the second wiring layer N 2  and the third wiring layer N 3 . The two wiring layers M 1 , M 2  include a single wiring pattern  50   b,    60   b,  respectively, that is not divided into wiring patterns. 
     That is, as shown in  FIGS. 3A and 3B , a coil apparatus of the third embodiment includes a single coil pattern that is not divided coil patterns. The single coil patterns are formed on one or more wiring layers, which are disposed below the second wiring layer N 2  provided just below the first wiring layer (the uppermost wiring layer) N 1 , and which are disposed above the third wiring layer N 3  provided just above the fourth wiring layer (lowermost wiring layer) N 4 . 
     Further, in an end portion of the coil patterns formed on the each wiring layers M 1 , M 2  that are not susceptible to leakage flux leaking from a core, it is possible to serially connect the coil patterns formed on the respective wiring layers M 1 , M 2  by at least one via-hole. Thus, in case that the number of the wiring layers (the number of laminated layers) is equal to that in the first embodiment, the number of the via-holes in the third embodiment becomes smaller than that in the first embodiment. 
     Thus, a region where the wiring pattern can be formed becomes wider, so that it is prevented that the wiring length of the wiring pattern becomes longer. 
     According to the coil apparatus of the third embodiment in the present invention, the same effect as the first embodiment can be obtained. 
     In addition, the first embodiment and second embodiment has been described that the whole or a part of the coil pattern is divided into two wiring patterns, which have the same width, by a single slit. But the invention is not limited thereto and may also have other configuration that the whole or a part of the coil pattern is divided into a plurality of wiring patterns by a plurality of slits. 
     For instance, in case that the whole or a part of a coil pattern is divided into three wiring patterns, which have the same width, by two slits, an outermost wiring pattern on a first wiring layer is serially connected to an innermost wiring pattern on a second wiring layer through a via-hole, an innermost wiring pattern on the second wiring layer is serially connected to an outermost wiring pattern on a third wiring layer through a via-hole, and an outermost wiring pattern on the third wiring layer is serially connected to an innermost wiring pattern on a fourth wiring layer through a via-hole (a first type of serial connecting wiring pattern). 
     Further, an intermediate wiring pattern on the first wiring layer is serially connected to an intermediate wiring pattern on the second wiring layer through a via-hole, the intermediate wiring pattern on the second wiring layer is serially connected to an intermediate wiring pattern on the third wiring layer through a via-hole, and the intermediate wiring pattern on the third wiring layer is serially connected to an intermediate wiring pattern on the fourth wiring layer through a via-hole (a second type of serial connecting wiring pattern). 
     Furthermore, an innermost wiring pattern on the first wiring layer is serially connected to an outermost wiring pattern on the second wiring layer through a via-hole, the outermost wiring pattern on the second wiring layer is serially connected to an innermost wiring pattern on the third wiring layer through a via-hole, and the innermost wiring pattern on the third wiring layer is serially connected to an outermost wiring pattern on the fourth wiring layer through a via-hole (a third type of serial connecting wiring pattern). 
     Therefore, the lengths L 401 , L 402  and L 403  of the first, second, third types of serial connecting wiring patterns become equal to each other, so that resistance values thereof become equal to each other, and so that respective currents flowing through the wiring patterns divided into three sections can be balanced. 
     The first and second embodiments have been described that are adapted to four-layered wiring layers. But the invention is not limited thereto and may also be adapted to wiring layer including an even number of layers. For instance, in case of two-layered wiring layers, it may be configured so that a third wiring layer N 3  (N 3   a ) and a fourth wiring layer N 4  (N 4   a ) are omitted. 
     The coil apparatus of the invention is applicable to a coil apparatus such as a transformer, an inductor or the like which requires to be made smaller and thinner.