Patent Document

BACKGROUND OF THE INVENTION  
         [0001]    This invention relates to a side-by-side coil inductor.  
           [0002]    Many electrical components, and electrical inductors in particular, have length and width dimensions which differ by a factor of 1.5 to 2.5 to facilitate component orientation. This is done to avoid mispositioning a square part by automated robotic assembly equipment which utilizes the size for proper orientation. In this process square components can be rotated 90° from the proper orientation. Proper orientation is important for yielding the proper electrical characteristics, and improper orientation can result in electrical defects.  
           [0003]    Inductors are elongated conductors which can take many shapes: straight, wound in a shape such as an oval, square, round, or many other configurations. The maximum inductance from a length of wire requires it to be in the shape of a circle.  
           [0004]    Many prior art inductors utilize an oval shaped coil pattern. FIGS. 1 and 2 illustrate these typical prior art inductors.  
           [0005]    Referring to FIG. 1 the numeral  10  generally designates a typical prior art monolithic chip inductor. Inductor  10  comprises a plurality of sub assemblies stacked upon one another. A bottom sub assembly  20  includes a ferrite bottom layer  22  and a bottom coil inductor  24  printed over ferrite layer  22 . Coil conductor  24  has an outer end  26  and an inner end  28 . The bottom ferrite layer  22  includes a front edge  14 , a rear edge  16  and opposite side edges  18 .  
           [0006]    Printed over the bottom subassembly  20  is a first intermediate subassembly  30 . Subassembly  30  includes a first intermediate ferrite layer  32  having a via hole  34  extending therethrough. Via hole  34  is registered immediately above the inner coil end  28  of bottom conductor coil  24 .  
           [0007]    Printed over the upper surface of first intermediate ferrite layer  32  is a first intermediate coil conductor  36  having an outer end  40 . Via hole  34  is filled with a conductive filler  42  which provides electrical connection between an inner end  38  of the first intermediate coil  36  and an inner end  28  of bottom coil  24 .  
           [0008]    Printed above the first intermediate subassembly  30  is a second intermediate subassembly  44  having a second ferrite layer  46  formed with a via hole  48  and having a second intermediate coil conductor  50  printed on the second intermediate ferrite layer  46 . Second intermediate coil conductor  50  has an outer end  52  registered above via hole  48 . Via hole  48  is filled with a conductive filler  56  registered above the outer coil end  40  of first intermediate coil  36 . Conductive filler provides electrical connection between the outer coil end  40  of the first intermediate coil  36  and the outer coil end  52  of second intermediate coil  50 . Second intermediate coil  50  also includes an inner end  54 .  
           [0009]    Printed above a second intermediate subassembly  44  is a top subassembly  58  which comprises a top ferrite layer  60  having a via hole  62  extending therethrough and a top coil conductor  64  printed over the upper surface thereof. Top coil conductor  64  includes a first end  66  and a second end  68 . End  68  functions as a terminal and extends to the end edge of top ferrite layer  60 . First terminal  66  is positioned above the via hole  62 . Conductive filler  69  is within via hole  62  and provides electrical connection between the top terminal  66  and the inner coil end  54  of the second intermediate coil conductor  50 .  
           [0010]    A ferrite top cap layer  70  is printed over the top subassembly  58  and covers the top subassembly  58 .  
           [0011]    [0011]FIG. 2 illustrates schematically the typical prior art coil structure provided by the exploded view shown in FIG. 1. The coil commences at its lower end  26  and proceeds in a helical pattern upwardly until it reaches the upper end  68 . The general configuration of the coil assembly  10  is rectangular or ovular. That is its length is substantially greater than its width. This enables a robotic assembly of the component into a circuit, and the robotic equipment can sense the rectangular shape of the assembly so as to permit it to be properly oriented within the circuitry.  
           [0012]    However, the rectangular or ovular shape of the coils within the coil assembly detracts from the maximum inductance which can be obtained. Inductance is maximum with a circle or a square configuration.  
           [0013]    The primary object of the present invention is the provision of an improved coil conductor.  
           [0014]    A further object of the present invention is the provision of an improved coil inductor that utilizes the same rectangular space of prior coil inductors, but provides two circular or square coils within that space.  
           [0015]    A further object of the present invention is the provision of an improved coil conductor which utilizes two circular or square coils in side-by-side relationship to maximize the inductance for parts of the same size.  
           [0016]    A further object of the present invention is the provision of an improved side-by-side coil conductor which is economical to manufacture, durable in use, and efficient in operation.  
         SUMMARY OF THE INVENTION  
         [0017]    A side-by-side coil inductor includes a first coil comprising a plurality of conductive first coil segments positioned one above another. The first coil segments are connected together in series. A second coil includes a plurality of conductive second coil segments positioned one above another. The second coil segments are also connected together in series. The first and second coils are in side-by-side position relative to one another and are connected together in series.  
           [0018]    According to one feature of the invention a plurality of ferrite layers alternate between adjacent pairs of the first coil layers and between adjacent pairs of the second coil layers to create an inductor body having an elongated shape with a body length greater than the body width.  
           [0019]    According to another feature of the invention the first and second coils have approximately the same width and length to maximize their inductance. Preferably they are square or circular in configuration, but they may have other similar configurations without detracting from the invention. 
       
    
    
     BRIEF DESCRIPTION OF THE FIGURES OF THE DRAWINGS  
       [0020]    [0020]FIG. 1 is an exploded perspective view of a prior art inductor coil.  
         [0021]    [0021]FIG. 2 is a schematic view of the prior art inductor coil of FIG. 1.  
         [0022]    [0022]FIG. 3 is an exploded perspective view of the side-by-side coil inductor of the present invention.  
         [0023]    [0023]FIG. 4 is a schematic view of the side-by-side coil inductor of the present invention.  
         [0024]    [0024]FIG. 5 is a perspective view of an inductor body showing the coil inductor within. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0025]    Referring to FIGS. 3 and 4 a side-by-side coil inductor  72  includes a bottom ferrite layer  74 . First and second conductive bottom coil segments  76 ,  78  are fitted on the upper surface of the bottom ferrite layer  74 . A coil connecting section  80  connects the two bottom segments  76 ,  78  in series with one another. Each of the bottom coil segments  76 ,  78  include an inner end  82 ,  84  respectively.  
         [0026]    A second ferrite layer  86  is superimposed over the first ferrite layer  74  and includes first and second coil segments  88 ,  90  which are in registered alignment above the bottom coil segments  76 ,  78 .  
         [0027]    Each of the first and second coil segments  88 ,  90  includes an inner end  92 ,  94  respectively and an outer end  96 ,  98  respectively. Second ferrite layer  86  is provided with a first via hole  100  and a second via hole  102  registered below the inner ends  92 ,  94  respectively of the coil segments  88 ,  90 . Within the via holes  100  and  102  are a first via fill  104  and a second via fill  106  respectively. Via fill  104  provides electrical connection between the inner end  92  of coil segment  88  and the inner end  82  of coil segment  76 . Similarly the via fill  106  provides electrical connection between the inner end  94  of coil segment  90  and the inner end  84  of the coil segment  78 .  
         [0028]    A third ferrite layer  108  includes first and second coil segments  110 ,  112  mounted on the upper surface thereof. Coil segments  110 ,  112  include inner ends  114 ,  116  respectively and outer ends  118 ,  120  respectively. The third ferrite layer  108  also includes via holes  122 ,  124  which are registered below the outer ends  118  and  120  respectively of the coil segments  110 ,  112 . Within the via holes  122 ,  124  are a first via fill  126  and a second via fill  128  which provide electrical connection between the outer ends  118 ,  120 , of coil segments  110 ,  112  and the outer ends  96 ,  98  of coil segments  88 ,  90  respectively.  
         [0029]    A fourth ferrite layer  130  includes first and second coil segments  132 ,  134  thereon. Each of the coil segments includes an inner end  136 ,  138  respectively and an outer end  142 ,  140  respectively. Registered below the inner end  136  is a first via opening  144  and registered beneath the inner end  138  is a second via opening  146 . Via openings  144 ,  146  are filled with conductive via fills  148 ,  150  respectively. Via fills  148 ,  150  provide electrical connection between the inner end  136  of coil segment  132  and the inner end  114  of coil segment  110  and also provide communication between the inner end  138  of coil segment  134  and the inner end  116  of coil segment  112 .  
         [0030]    A cap ferrite layer  152  includes a first terminal  154  and a second terminal  156  imprinted thereon. A first cap via opening  158  is registered below first terminal  154  and a second cap via opening  160  is registered below second terminal  156 . Via fills  162 ,  164  are mounted within the via holes  158 ,  160  and provide electrical communication between terminals  154 ,  156  and outer ends  142 ,  140  respectively of coil segments  132 ,  134 . The number of layers of coil segments may be increased or decreased according to the inductance desired. Also, the terminals  154 ,  156  may be located on the top sides, or on combinations of surfaces of inductor body  72  without detracting from the invention.  
         [0031]    [0031]FIG. 4 illustrates schematically the side-by-side coil configuration which is formed by the structure shown in FIG. 3. The coil commences at terminal  154  and progresses helically downwardly to coil segment  76 . It then connects by means of connector segment  80  to the bottom coil segment  78  and progresses helically upwardly to the terminal  156 . Preferably coil segments  132 ,  110 ,  88 ,  76  are all rectangular or circular in configuration and are not elongated or ovular or rectangular as in prior art devices. Similarly, the configurations  78 ,  90 ,  112 ,  134  are all circular or square in configuration and are not ovular, elongated or rectangular as in prior art devices. However, other configurations may be used for the coil segments including rectangular configurations. Using square or circular coil segments maximizes inductance.  
         [0032]    Each of the coil segments is shown as progressing slightly further then 360° within the segment. However, the particular configuration may vary and the number of degrees in each coil segment can vary without detracting from the invention. The number of degrees in each coil segment can be greater than 360° or less than 360° as desired.  
         [0033]    The assembled inductor  72  is shown in FIG. 5. If desired a dielectric coating may be used to cover the inductor  72 , but leaving terminals  154 ,  156  exposed. Inductor  72  is rectangularly shaped. The rectangular shape makes possible the robotic assembly of the inductor assembly  72  into an electrical circuitry because the robotic equipment can sense the rectangular shape of the inductance assembly  72  and orient it properly. Thus a rectangular overall inductance assembly is achieved, while at the same time achieving the maximum inductance obtainable with a square or circular configuration within each coil segment.  
         [0034]    The preferred implementation of the present invention may utilize a multilayer ceramic build-up technique such as thick film or low temperature cofired tape. The body is composed of a ferrite material while the conductive coil material is preferably silver or silver/palladium. The same results could be achieved by utilizing other thick film body materials and conductor materials as well as completely different techniques like traditional copper wire coil winding techniques used in molded bodies.  
         [0035]    In the drawings and specification there has been set forth a preferred embodiment of the invention, and although specific terms are employed, these are used in a generic and descriptive sense only and not for purposes of limitation. Changes in the form and the proportion of parts as well as in the substitution of equivalents are contemplated as circumstances may suggest or render expedient without departing from the spirit or scope of the invention as further defined in the following claims.

Technology Category: 5