Abstract:
There is provided a spiral inductor including an insulation board formed into a flat-plate shape; a conductive pattern having a spiral shape and formed at least one surface of the insulation board, wherein the conductive pattern varies in line width according to a distance from one end of the conductive pattern forming a spiral.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the priority of Korean Patent Application No. 2007-56853 filed on Jun. 11, 2007, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a spiral inductor, and more particularly, to an inductor having a spiral conductive pattern forming the inductor that has line width varying in a length direction of the spiral. 
         [0004]    2. Description of the Related Art 
         [0005]      FIG. 1  is a view illustrating a structure of a spiral inductor according to the related art. 
         [0006]    Referring to  FIG. 1 , a conductive pattern  12  having a spiral structure is formed on an insulation board  11 . 
         [0007]    The insulation board  11  is formed of a printed wiring board or the like. The conductive pattern  12  that forms an inductor and has the spiral shape is formed at one surface of the insulation board  11 . 
         [0008]    The conductive pattern  12  that forms the inductor has a constant width in a length direction of the spiral shape with the loops of the spiral being a constant distance apart. 
         [0009]    Further, one end  12   a  positioned at the edge of the conductive pattern  12  and the other end positioned at the center thereof may be connected to input and output terminals, respectively. When a current flows from the one terminal  12   a , the current flows in directions indicated by arrows A 1 , A 2 , A 3 , and A 4  toward the other terminal  12   b.    
         [0010]    As described above, when the conductive pattern of the spiral inductor has the constant line width, and the spiral of the conductor has the loops at the constant distance apart, the inductance of the inductor may be reduced. That is, when the current is supplied to the spiral inductor, the current flows through the loops of the spiral of the conductive pattern  12  forming the inductor that face each other on the basis of a center of the conductive pattern  12  along opposite directions (A 1  and A 3 , and A 2  and A 4 ). The loops of the spiral of the conductor that face each other are affected by magnetic lines of force generated around each other to thereby reduce the inductance of the inductor. 
         [0011]    As such, the spiral inductor according to the related art has a structure in which the inductor has the constant width and the spiral loops of the conductive pattern are affected by the magnetic lines of force generated around each other. This causes reductions in inductance and quality (Q) factor. 
       SUMMARY OF THE INVENTION 
       [0012]    An aspect of the present invention provides a spiral inductor that has a high quality factor by preventing deterioration in performance caused by interaction between loops of a spiral conductive pattern. 
         [0013]    According to an aspect of the present invention, there is provided a spiral inductor including an insulation board formed into a flat-plate shape; a conductive pattern having a spiral shape and formed at least one surface of the insulation board, wherein the conductive pattern varies in line width according to a distance from one end of the conductive pattern forming a spiral. 
         [0014]    The conductive pattern may be formed by alternating a first region decreasing in line width and a second region increasing in line width according to distances from one end of the conductive pattern forming the spiral. 
         [0015]    Each of the first region and the second region of the conductive pattern may form one turn. 
         [0016]    The conductive patterns may be formed at both surfaces of the insulation board and have ends thereof connected to each other by a conductive via hole formed through the insulation board. 
         [0017]    At least portions of the conductive patterns formed at both surfaces of the insulation board may overlap with each other. 
         [0018]    According to another aspect of the present invention, there is provided a spiral inductor including: a plurality of conductive patterns having a spiral shape; at least one insulation board formed between the conductive patterns, wherein the plurality of conductive patterns vary in line width according to distances from ends of the individual conductive patterns forming spirals and are connected in series with each other by a conductive via hole formed through the insulation board. 
         [0019]    Each of the plurality of conductive patterns may be formed by alternating a first region decreasing in line width and a second region increasing in line width according to the distance from one end of the conductive pattern forming the spiral. 
         [0020]    Each of the first region and the second region of each of the plurality of conductive patterns may form one turn. 
         [0021]    At least portions of the plurality of conductive patterns may overlap with each other. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]    The above and other aspects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
           [0023]      FIG. 1  is a graph illustrating a structure of a spiral inductor according to the related art. 
           [0024]      FIG. 2  is a view illustrating a structure of a spiral inductor according to an exemplary embodiment of the present invention. 
           [0025]      FIG. 3  is a view illustrating a structure of a spiral inductor according to another exemplary embodiment of the present invention. 
           [0026]      FIG. 4  is an exploded perspective view illustrating a spiral inductor according to still another exemplary embodiment of the present invention. 
           [0027]      FIG. 5  is a graph illustrating a Q value of a spiral inductor according to the exemplary embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0028]    Exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. 
         [0029]      FIG. 2  is a view illustrating a structure of a spiral inductor according to an exemplary embodiment of the invention. 
         [0030]    Referring to  FIG. 2 , a spiral inductor according to an exemplary embodiment of the invention includes an insulation board  21  and a conductive pattern  22 . The conductive pattern  22  having a spiral shape is formed at the insulation board. 
         [0031]    The spiral conductive pattern  22  may vary in line width according to a distance from the one end  22   a  of the spiral conductive pattern. 
         [0032]    The spiral conductive pattern  22  may be formed by alternating a first region increasing in line width and a second region decreasing in line width. 
         [0033]    In this embodiment, the spiral conductive pattern may have a rotation number (turn number) of 3.5. The spiral conductive pattern  22  may include a first line  22 - 1  decreasing in line width, a second line  22 - 2  increasing in line width, a third line  22 - 3  decreasing in line width, and a fourth line  22 - 4  increasing in line width according to distances from the one end  22   a  of the conductive pattern. 
         [0034]    The first line  22 - 1  has one end  22   a  that may be connected to an input terminal IN through which a current can be supplied to the conductive pattern. The fourth line  22 - 4  has one end  22   b  that may be connected to an output terminal OUT. 
         [0035]    The input terminal IN may be formed on the same plane as the conductive pattern. The output terminal OUT may be formed on a different plane from that of the conductive pattern and be connected to the fourth line  22 - 4  through a conductive via hole. 
         [0036]    The first line  22 - 1  and the third line  22 - 3  correspond to second regions that decrease in line width according to the distances from the one end  22   a  of the conductive pattern, and the second line  22 - 2  and the fourth line  22 - 4  correspond to the first regions that increase in line width along a length direction. 
         [0037]    In this embodiment, the spiral conductive pattern formed by alternating a configuration in which the line width increases and a configuration in which line width decreases according to the distances from the one end  22   a  of the spiral conductive pattern. Therefore, it is possible to solve the above-described problems, that is, the reductions in inductance and Q factor due to interaction between the magnetic lines of force generated around the loops of the spiral conductive pattern of the spiral inductor having the constant width. 
         [0038]    That is, when the current is supplied to the conductive pattern  22 , the current flows in order of directions A 1 , A 2 , A 3 , A 4 , A 5 , A 6 , and A 7 . The current flows through the loops of the spiral conductive pattern  22  that face each other on the basis of a center point O 1  of the spiral conductive pattern  22  in opposite directions (A 1  and A 2 , A 3  and A 4 , and A 5  and A 6 ). However, the loops of the spiral conductive pattern do not have the same line widths as each other but gradually increase or decrease. Since the loops are positioned at varying distances from the center point O 1 , they may be affected less by magnetic lines of force generated around each other, and the inductance may increase. 
         [0039]    As such, when the inductance of the inductor formed of the spiral conductive pattern  22  increases, the Q factor also increases. 
         [0040]      FIG. 3  is an exploded perspective view of a spiral inductor according to another exemplary embodiment of the invention. 
         [0041]    Referring to  FIG. 3 , a spiral inductor according to this embodiment includes an insulation board  31 , a first conductive pattern  32 , and a second conductive pattern  33 . The first and second conductive patterns  32  and  33  are formed at both surfaces of the insulation board  31 . 
         [0042]    The insulation board  31  may be formed of ferromagnetic ceramics, such as ferrite having a predetermined dielectric constant, or non-ferromagnetic ceramics. 
         [0043]    The first conductive pattern  32  and the second conductive pattern  33  may vary in line width according to distances from ends  32   a  and  33   a  of the conductive patterns forming a spiral, respectively. 
         [0044]    Each of the spiral first conductive pattern  32  and the spiral second conductive pattern  33  may be formed by alternating a first region increasing in line width and a second region decreasing in line width according to distances from the one end of the conductive pattern. 
         [0045]    In this embodiment, the first conductive pattern  32  may have a rotation number (turn number) of 3.5. The first conductive pattern  32  may include a first line  32 - 1  decreasing in line width, a second line  32 - 2  increasing in line width, a third line  32 - 3  decreasing in line width, and a fourth line  32 - 4  increasing in line width. 
         [0046]    The first conductive pattern  32  may have one end  32   a  that may be connected to an input terminal IN through which a current can be supplied to the conductive pattern  32 . The first conductive pattern  32  may have the other end  32   b  that may be connected to one end  33   a  of the second conductive pattern through a conductive via hole  31 - 1  formed in the insulation board  31 . 
         [0047]    The second conductive pattern  33  may have a rotation number (turn number) of 3. The second conductive pattern  33  may include a first line  33 - 1  decreasing in line width, a second line  33 - 2  increasing in line width, and a third line  33 - 3  decreasing in line width according to a distance from the one end  33   a  of the conductive pattern. 
         [0048]    The one end  33   a  of the second conductive pattern is connected to the other end  32   b  of the first conductive pattern through the conductive via hole  33 - 1  formed in the insulation board  31 . The other end  33   b  of the second conductive pattern may be connected to the output terminal OUT of the current. 
         [0049]    In this embodiment, the input terminal IN may be formed on the same plane as the first conductive pattern, and the output terminal OUT may be formed on the same plane as the second conductive pattern. 
         [0050]    In this embodiment, each of the first and second conductive patterns is formed by alternating a configuration in which line width increases and a configuration in which line width decreases according to the distances from each of the ends  32   a  and  33   a  of the conductive pattern forming the spiral. Therefore, it is possible to solve the above-described problems, that is, the reductions in inductance and Q factor due to interaction between the magnetic lines of force generated around the loops of the spiral conductive pattern of the spiral inductor having the constant width. 
         [0051]    That is, the current flows through the first conductive pattern  32  in order of directions A 1 , A 2 , A 3 , A 4 , A 5 , A 6 , and A 7 . The current flows through the loops of the spiral conductive pattern that face each other on the basis of a center point O 1  of the spiral conductive pattern  32  in opposite directions A 1  and A 2 , A 3  and A 4 , and A 5  and A 6 . However, the line widths are the same as each other but decrease or increase gradually. Therefore, since the distances from the center point O 1  are the same as each other, the loops of the conductive pattern that face each other on the basis of the center point O 1  are affected less by magnetic lines of force generated around each other, and the inductance of the conductive pattern may increase. 
         [0052]    The current flowing through the first conductive pattern  32  is supplied to the second conductive pattern  33  through the conductive via hole  31 - 1 . The current flows through the second conductive pattern  33  in order of directions B 1 , B 2 , B 3 , B 4 , B 5 , and B 6 . 
         [0053]    Like the first conductive pattern, the current flows through the loops of the second conductive pattern  33  having the spiral shape that face each other on the basis of a center point O 2  of the second conductive pattern  33  having the spiral shape in opposite directions B 1  and B 2 , B 3  and B 4 , and B 5  and B 6 . Therefore, the loops of the conductive pattern that face each other on the basis of the center point O 2  are affected less by magnetic lines of force generated around each other, and the inductance of the second conductive pattern may increase. 
         [0054]    The center point O 1  of the first conductive pattern  32  and the center point O 2  of the second conductive pattern  33  may be positioned along the same vertical line. 
         [0055]    The first conductive pattern  32  and the second conductive pattern  33  may partially overlap with each other. Further, the current may flow through the overlapping portion between the first and conductive patterns in the same direction. 
         [0056]    The loops of each of the two spirals are a distance apart so that outermost loops of the spirals correspond to each other. 
         [0057]    In this embodiment, the first line  32 - 1  of the first conductive pattern and the first line  33 - 1  of the second conductive pattern partially overlap with each other, and the current may flow through the overlapping portion in the same direction (A 1  and B 6 , and A 2  and B 5 ). 
         [0058]    Further, the second line  32 - 2  of the first conductive pattern and the second line  33 - 2  of the second conductive pattern partially overlap with each other, and the current may flow through the overlapping portion in the same direction (A 3  and B 4 , and A 4  and B 3 ). The third line  32 - 3  of the first conductive pattern and the third line  33 - 3  of the second conductive pattern partially overlap with each other, and the current may flow through the overlapping portion in the same direction (A 5  and B 2 , and A 6  and B 1 ). 
         [0059]    As such, since at least portions of the spiral conductive patterns formed at both surfaces of the insulation board overlap with each other, and the current flows through the overlapping portions in the same direction, an electrical length of the inductor with the same area can be increased to thereby reduce the size of the inductor. 
         [0060]      FIG. 4  is an exploded perspective view illustrating a spiral inductor according to another exemplary embodiment of the present invention. 
         [0061]    Referring to  FIG. 4 , a spiral inductor according to this embodiment may include a plurality of conductive patterns  42 ,  52 , and  62  each having a spiral shape and a plurality of insulation boards  41 ,  51 , and  61  each formed between the conductive patterns. 
         [0062]    In this embodiment, the insulation boards  41 ,  51 , and  61  may include a first insulation board  41 , a second insulation board  51 , and a third insulation board  61 . The first, second, and third insulation boards  41 ,  51 , and  61  may include conductive via holes  41 - 1 ,  51 - 1 , and  61 - 1  formed in the insulation boards, respectively. Each of the conductive via holes  41 - 1 ,  51 - 1 , and  61 - 1  electrically connects the conductive patterns formed at upper and lower surfaces of each of the insulation boards. 
         [0063]    In this embodiment, the plurality of spiral conductive patterns may include the first conductive pattern  42 , the second conductive pattern  52 , and the third conductive pattern  62 . Each of the conductive patterns  42 ,  52 , and  62  may vary in line width along a length direction of conducting wires forming the spiral shape. 
         [0064]    Each of the first, second, and third conductive patterns  42 ,  52 , and  62  having the spiral shapes may be formed by alternating a first region increasing in line width and a second region decreasing in line width according to distances from one end of each of the conductive patterns. 
         [0065]    In this embodiment, the first conductive pattern  42  may have a rotation number (turn number) of 3.5. The first conductive pattern  42  may include a first line  42 - 1  decreasing in line width, a second line  42 - 2  increasing in line width, a third line  42 - 3  decreasing in line width, and a fourth line  42 - 4  increasing in line width according to distances from one end  42   a  of the conductive pattern  42 . 
         [0066]    The first conductive pattern  42  has the one end  42   a  that may be connected to an input terminal IN through which a current can be supplied to the conductive pattern. The first conductive pattern  42  also has the other end  42   b  that may be connected to one end  52   a  of the second conductive pattern by a conductive via hole  41 - 1  formed in the first insulation board  41 . 
         [0067]    The second conductive pattern  52  may have a rotation number (turn number) of 3.5. The second conductive pattern  52  may include a first line  52 - 1  decreasing in line width, a second line  52 - 2  increasing in line width, a third line  52 - 3  decreasing in line width, and a fourth line  52 - 4  increasing in line width according to a distance from the one end  52   a  of the conductive pattern. 
         [0068]    The second conductive pattern has the one end  52   a  that may be connected to the other end  42   b  of the first conductive pattern by the conductive via hole  41 - 1 . The other end  52   b  of the second conductive pattern may be connected to one end  62   a  of the third conductive pattern by the conductive via hole  51 - 1  formed in the second insulation board. 
         [0069]    The third conductive pattern  62  may have a rotation number (turn number) of 3.5. The third conductive pattern  62  may include a first line  62 - 1  decreasing in line width, a second line  62 - 2  increasing in line width, a third line  62 - 3  decreasing in line width, and a fourth line  62 - 4  increasing in line width according to distances from the one end  62   a  of the conductive pattern. 
         [0070]    The one end  62   a  of the third conductive pattern may be connected to the one end  52   b  of the second conductive pattern by the conductive hole  51 - 1  of the conductive via hole  51 - 1 . The other end of the third conductive pattern may be connected to an output terminal OUT through the conductive via hole  61 - 1  formed in the third insulation board. 
         [0071]    According to the embodiment of the invention, the conductive pattern forming the inductor may be formed by alternating a configuration in which line width increases and a configuration in which line width decreases according to distances from one end of the spiral conductive pattern. Therefore, it is possible to solve the problems of the reductions in inductance and Q factor due to interaction between the magnetic lines of force generated around the loops of the spiral conductive pattern of the spiral inductor having the constant width. 
         [0072]    That is, the current flows through the first conductive pattern  42  in order of directions A 1 , A 2 , A 3 , A 4 , A 5 , A 6 , and A 7 . The current flows through the loops of the conductive pattern  42  that face each other on the basis of a center point O 1  of the spiral conductive pattern  42  in opposite directions (A 1  and A 2 , A 3  and A 4 , and A 5  and A 6 ). However, since the loops have line widths that are not the same as each other but increase or decrease gradually, distances from the center point O 1  are different from each other. Therefore, the loops are affected less by magnetic lines of force generated around each other, and the inductance of the first conductive pattern may increase. 
         [0073]    The current flowing through the first conductive pattern  42  is supplied to the second conductive pattern  52  through the conductive via hole  41 - 1 . The current flows through the second conductive pattern in order of directions B 1 , B 2 , B 3 , B 4 , B 5 , B 6 , and B 7 . 
         [0074]    The current flowing through the second conductive pattern  52  is supplied to the third conductive pattern  62  through the conductive via hole  51 - 1 . The current flows through the third conductive pattern in order of directions C 1 , C 2 , C 3 , C 4 , C 5 , C 6 , and C 7 . 
         [0075]    In the same manner, the current may flow through the loops of each of the second and third conductive patterns  52  and  62  having the spiral shape that face each other on the basis of the center point (O 2  or O 3 ) thereof in opposite directions (B 1  and B 2 , B 3  and B 4 , and B 5  and B 6  or C 1  and C 2 , C 3  and C 4 , and C 5  and C 6 ). Therefore, the influence of the loops of the spiral conductive pattern that face each other on the basis of each of the center points O 2  and O 3  are affected less by magnetic lines generated around each other and the inductance of the spiral conductive pattern may increase. 
         [0076]    The center point O 1  of first conductive pattern  42 , the center point O 2  of the second conductive pattern  52 , and the center point O 3  of the third conductive pattern  62  may be positioned on the same vertical line. 
         [0077]    The first conductive pattern  42 , the second conductive pattern  52 , and the third conductive pattern  62  may partially overlap with each other. Further, the current may flow through the overlapping portions between the conductive patterns in the same direction. 
         [0078]    The loops of each of the three spirals are a constant distance apart so that outermost loops of the spirals correspond to each other. 
         [0079]    In this embodiment, the first line  42 - 1  of the first conductive pattern, the first line  52 - 1  of the second conductive pattern, and the first line  62 - 1  of the third conductive pattern partially overlap with each other, and the directions (A 1 , B 6 , and C 1 ) in which the current flows through the overlapping portions may be the same as each other. 
         [0080]    Further, the second line  42 - 2  of the first conductive pattern, the second line  52 - 2  of the second conductive pattern, and the second line  62 - 2  of the third conductive pattern partially overlap with each other. The directions (A 3 , B 4 , C 3 ) in which the current flows through the overlapping portions may be the same as each other. The third line  42 - 3  of the first conductive pattern, the third line  52 - 3  of the second conductive pattern, and the third line  62 - 3  of the third conductive pattern partially overlap with each other, and the directions (A 5 , B 2 , C 5 ) in which the current flows through the overlapping portions may be the same as each other. 
         [0081]    As such, the plurality of spiral conductive patterns and the plurality of insulation boards are laminated, at least portions of the laminated spiral conductive patterns overlap with each other, and the current flows through the overlapping portions in the same direction. Therefore, the electrical length of the inductor with the same area can be increased to thereby reduce the inductance. 
         [0082]      FIG. 5  is a graph illustrating a Q value of a spiral inductor according to an exemplary embodiment of the invention. 
         [0083]    Referring to  FIG. 5 , a curve A indicates a Q value according to frequency of a spiral inductor according to the related art, and a curve B indicates a Q value according to frequency of the spiral inductor according to the embodiment of the invention. 
         [0084]    In this embodiment, the spiral inductor according to the related art includes eight layers of conductive patterns each having an area of 346×204 μm 2  and a line width of 9 μm. An innermost loop of the spiral conductive pattern has a diameter of 120 μm, and the loops of the spiral are a distance of 3 μm apart. The spiral has a turn number of 3.5. 
         [0085]    In the graph of  FIG. 5 , the spiral inductor according to the embodiment of the invention has a maximum Q value of approximately 21, and the inductor according to the related art has a maximum Q value of approximately 15. Therefore, according to the embodiment of the invention, the spiral inductor according to the embodiment of the invention increases characteristics by approximately 30% than the spiral inductor having the constant line width according to the related art. 
         [0086]    As set forth above, according to the exemplary embodiments of the invention, it is possible to manufacture a spiral inductor that can be reduced in size as compared with the spiral inductor according to the related art and has higher inductance and a higher Q for the same area. 
         [0087]    While the present invention has been shown and described in connection with the exemplary embodiments, it will be apparent to those skilled in the art that modifications and variations can be made without departing from the spirit and scope of the invention as defined by the appended claims.