Patent Publication Number: US-2010117780-A1

Title: Conductive winding assembly and fabricating method thereof

Description:
FIELD OF THE INVENTION 
     The present invention relates to a conductive winding module, and more particularly to a slim-type conductive winding module. The present invention also relates to a method for fabricating such a conductive winding module. 
     BACKGROUND OF THE INVENTION 
     Nowadays, magnetic elements such as inductors and transformers are widely used in many electronic devices to generate induced magnetic fluxes. Recently, since the electronic devices are developed toward minimization, the electronic components contained in the electronic products become small in size and light in weight. For example, a flat coil is used as the conductive winding assembly of the magnetic element. 
     Take a transformer for example. In the transformer, a primary winding coil and a secondary winding coil are wound around a bobbin. Since the bobbin should have a winding section for winding the primary winding coil and the secondary winding coil, the volume of the bobbin is very bulky. For reducing the overall volume of the transformer, the conductive winding module is fabricated by bending multiple copper plates as a multi-loop structure. For isolation, insulating tapes should be previously attached on the surfaces of these copper plates before the bending procedure. As known, the procedure of attaching the insulating tapes is labor-intensive and time-consuming and thus the fabricating cost is increased. Moreover, the thicknesses of the insulating tapes are detrimental to volume reduction of the conductive winding module. If the insulating tapes are scraped off the copper plates, the problem of causing short circuit occurs. 
     There is a need of providing an improved conductive winding module and the fabricating method thereof in order to obviate the drawbacks encountered from the prior art. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a simplified and cost-effective method for fabricating a conductive winding module. 
     Another object of the present invention provides a conductive winding module with a multi-loop conductive structure in order to reduce the overall volume of the magnetic element. 
     In accordance with an aspect of the present invention, there is provided a method for fabricating a conductive winding module of a magnetic element. Firstly, a non-insulated winding structure including multiple conductive units is provided, wherein the conductive units have respective conductive bodies, and one or more of the conductive units have pins. Then, an insulating varnish layer is formed on surfaces of the conductive bodies, thereby producing the conductive winding module. 
     In accordance with another aspect of the present invention, there is provided a conductive winding module of a magnetic element. The conductive winding module includes a non-insulated winding structure and an insulating varnish layer. The non-insulated winding structure includes multiple conductive units. The conductive units have respective conductive bodies, and one or more of the conductive units have pins. The conductive bodies of the non-insulated winding structure are combined together to form an unbroken multi-loop structure. The insulating varnish layer is formed on surfaces of the conductive bodies, wherein the pins are not covered with the insulating varnish layer. 
     The above contents of the present invention will become more readily apparent to those ordinarily skilled in the art after reviewing the following detailed description and accompanying drawings, in which: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a flowchart illustrating a method for fabricating the conductive winding module of the present invention; 
         FIG. 2  is a schematic perspective view illustrating a non-insulated winding structure according to a first embodiment of the present invention; 
         FIG. 3  is a flowchart illustrating the steps of providing the non-insulated winding structure shown in  FIG. 2 ; 
         FIG. 4  is a schematic exploded view of the non-insulated winding structure shown in  FIG. 2 ; 
         FIG. 5  is a schematic perspective view illustrating the conductive winding module of the present invention; 
         FIG. 6  is a schematic exploded view illustrating a transformer having several conductive winding modules of  FIG. 5 ; and 
         FIG. 7  is a schematic exploded view illustrating an inductor having one conductive winding module of  FIG. 5 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The present invention will now be described more specifically with reference to the following embodiments. It is to be noted that the following descriptions of preferred embodiments of this invention are presented herein for purpose of illustration and description only. It is not intended to be exhaustive or to be limited to the precise form disclosed. 
     The present invention relates to a conductive winding module of a magnetic element. An example of the magnetic element includes but is not limited to an inductor or a transformer. 
       FIG. 1  is a flowchart illustrating a method for fabricating the conductive winding module of the present invention. First of all, a non-insulated winding structure is provided (S 11 ). The non-insulated winding structure includes multiple conductive units with multiple conductive bodies and multiple pins. Next, an insulating varnish layer is formed on the surfaces of the conductive bodies, thereby producing the conductive winding module of the present invention (S 12 ). 
       FIG. 2  is a schematic perspective view illustrating a non-insulated winding structure according to a first embodiment of the present invention.  FIG. 3  is a flowchart illustrating the steps of providing the non-insulated winding structure shown in  FIG. 2 .  FIG. 4  is a schematic exploded view of the non-insulated winding structure shown in  FIG. 2 . Please refer to  FIGS. 2 ,  3  and  4 . The non-insulated winding structure  2  includes multiple conductive units  20 , which are combined together by a high-temperature welding process. In this embodiment, four conductive units  20   a,    20   b,    20   c  and  20   d  are included in the non-insulated winding structure  2  for illustration. Each of these four conductive units  20   a,    20   b,    20   c  and  20   d  is a single conductive plate made of metallic material such as copper. It is preferred that these conductive plates have the same thickness. Each of the conductive units  20   a,    20   b,    20   c  and  20   d  includes a conductive body  201 . The shape of the conductive body  201  is varied according to the practical requirements. In this embodiment, the conductive body  201  is ring-shaped and has a central through-hole  203 . The non-insulated winding structure  2  further has several extension parts  202 , which are extended from the peripheries of some or all of the conductive units  20   a,    20   b ,  20   c  and  20   d.  As shown in  FIG. 4 , three extension parts  202  are respectively extended from the peripheries of the first conductive unit  20   a,  the second conductive unit  20   b  and the fourth conductive unit  20   d.    
     For assembling these four conductive units  20 , the conductive bodies  201  of adjacent conductive units  20  are successively combined together by a high-temperature welding process, wherein the through-holes  203  are aligned with each other. For example, the fourth conductive unit  20   d  and the third conductive unit  20   c  are simultaneously supported by a jig tool (not shown), wherein the through-holes  203  of the fourth conductive unit  20   d  and the third conductive unit  20   c  are aligned with each other and the welding ends  204  of the fourth conductive unit  20   d  and the third conductive unit  20   c  are contacted with each other. Next, by a high-temperature welding process, these two neighboring welding ends  204  are molten and then solidified as a joining seam  24   c  (see  FIG. 2 ). The joining seam  24   c  is a welding seam resulted from the high-temperature welding process. As a result, the conductive bodies  201  of the fourth conductive unit  20   d  and the third conductive unit  20   c  are smoothly connected with each other. Similarly, the welding ends  204  of the third conductive unit  20   c  and the second conductive unit  20   b  are molten and then solidified as a joining seam  24   b  by a high-temperature welding process, so that the conductive bodies  201  of the third conductive unit  20   c  and the second conductive unit  20   b  are smoothly connected with each other. Similarly, the welding ends  204  of the second conductive unit  20   b  and the first conductive unit  20   a  are molten and then solidified as a joining seam  24   a  by a high-temperature welding process, so that the conductive bodies  201  of the second conductive unit  20   b  and the first conductive unit  20   a  are smoothly connected with each other. 
     After the fourth conductive units  20  are connected with each other, the non-insulated winding structure  2  of the present invention is assembled. The resulting configurations of the non-insulated winding structure  2  are shown in  FIG. 2 . Meanwhile, the extension parts  202  are served as the pins  22  and the through-holes  203  of these fourth conductive units  20  collectively define a channel  23 . Since three extension parts  202  are respectively extended from the peripheries of the first conductive unit  20   a,  the second conductive unit  20   b  and the fourth conductive unit  20   d,  the non-insulated winding structure  2  has only three pins  22 . In other words, the non-insulated winding structure  2  is an unbroken four-loop structure with three pins in a staggered arrangement. 
     The number of the conductive units  20  and the number the pins  22  may be varied according to the practical requirements. In addition, the sequence of welding the conductive bodies  201  of neighboring conductive units  20  may be varied according to the practical requirements. 
     An example of the high-temperature welding process includes but is not limited to a laser welding process, an electron beam welding process or a plasma welding process. In some embodiments, the welding ends of the conductive units are optionally subject to a black treatment in order to reduce the reflectivity of the metallic plates. Due to the reduced reflectivity, the welding energy is concentrated and the joining seams  24   a,    24   b  and  24   c  have smooth appearance. 
     In some embodiments, the non-insulated winding structure  2  is formed in a mold (not shown) by an electroforming process. Under this circumstance, the non-insulated winding structure  2  is an integral structure. 
     After the non-insulated winding structure  2  is provided, an insulating varnish layer  25  is formed on the surfaces of the conductive bodies  21 , thereby producing the conductive winding module  2 ′ as shown in  FIG. 5 . The procedure of forming an insulating varnish layer on the surfaces of the conductive bodies includes for example a powder coating process, a spray coating process or a dipping process. 
     For carrying out the powder coating process, the non-insulated winding structure  2  is firstly placed on a coating chamber (not shown). Then, insulating varnish powder (e.g. epoxy resin powder) is negatively charged to be uniformly adsorbed on the surface of the non-insulated winding structure  2 . Then, a baking step is performed to melt the insulating varnish powder. After the molten insulating varnish powder is cooled, the insulating varnish layer  25  is formed on the surfaces of the conductive bodies  21 . The insulating varnish layer  25  offers an insulating efficacy so as to prevent the short-circuit problem. 
     For carrying out the dipping process, the conductive bodies  21  of the non-insulated winding structure  2  are immersed in a vessel filled with an insulating varnish solution. After a certain dipping period, the insulating varnish layer  25  is formed on the surfaces of the conductive bodies  21 . The insulating varnish solution includes for example melamine/alkyd impregnating varnish, epoxy resin dipping varnish or alkyd amino impregnating varnish. 
     For carrying out the spray coating process, polyurethane insulating varnish solution is sprayed onto the surfaces of the conductive bodies  21  by a spray gun, thereby forming the insulating varnish layer  25 . It is of course that the materials for forming the insulating varnish layer  25  are varied according to the practical requirements. 
     Please refer to  FIG. 5  again. After the magnetic element having the conductive winding module  2 ′ is fabricated, the pins  22  could be soldered onto corresponding contact pads or conductive holes of a system circuit board (not shown), so that the magnetic element is electrically connected with the system circuit board via the pins  22 . For marking electrical connection between the magnetic element and the system circuit board, the pins  22  are not covered with the insulating varnish layer  25 . For example, before the process of forming the insulating varnish layer  25  on the surfaces of the conductive bodies  21 , the pins  22  need to be previously covered with other insulating material. Alternatively, the insulating varnish layer  25  may be simultaneously formed on the surfaces of the conductive bodies  21  and the pins  22 , but the insulating varnish layer  25  covering the pins  22  need to be removed later. In other words, the pins  22  should keep electrically conductive but the surfaces of the conductive bodies  21  should be insulated from each other. Since the conductive bodies  21  and the pins  22  are conductive and thin and the insulating varnish layer  25  is substantially a thin film, the conductive winding module  2 ′ can be referred as a flat-type conductive winding module. 
     Please refer to  FIG. 5  again. In a case that the conductive winding module  2 ′ is compressed along the axel direction “a”, the gap between every two adjacent conductive bodies  21  of the conductive winding module  2 ′ is reduced. As such, the conductive winding module  2 ′ can be applied to a magnetic element such as a transformer or an inductor. 
       FIG. 6  is a schematic exploded view illustrating a transformer having several conductive winding modules of  FIG. 5 . As shown in  FIG. 6 , the transformer  3  principally includes a bobbin  4 , a magnetic core assembly  5  and several conductive winding modules  2 ′. The bobbin  4  includes a winding section  41 , a receiving part  42  and a hollow portion  43  running through the bobbin  4 . The cross-sectional profile of the bobbin  4  is similar to that of the conductive body  21  of the conductive winding module  2 ′. A primary winding assembly  6  is wound around the winding section  41  of the bobbin  4 . The conductive bodies  21  of two conductive winding modules  2 ′ are attached on bilateral sides of the bobbin  4 , and the conductive bodies  21  of one conductive winding module  2 ′ is accommodated within the receiving part  42 . These conductive winding modules  2 ′ are used as the secondary winding assemblies of the transformer  3 . When the conductive winding modules  2 ′ are combined with the bobbin  4 , the channels  23  of the conductive winding modules  2 ′ are aligned with the hollow portion  43  of the bobbin  4 . The magnetic core assembly  5  is partially embedded into the hollow portion  43  of the bobbin  4  and the channels  23  of the conductive winding modules  2 ′. When the pins  22  pins are soldered onto corresponding contact pads or conductive holes of a system circuit board (not shown), the transformer  3  is electrically connected with the system circuit board. As a result, the primary winding assembly  6  and the secondary winding assemblies (i.e. the conductive winding modules  2 ′) interact with the magnetic core assembly  5  to achieve the purpose of voltage regulation. Since the secondary winding assemblies are flat-type conductive winding modules  2 ′, the overall thickness of the transformer  3  is reduced. 
       FIG. 7  is a schematic exploded view illustrating an inductor having one conductive winding module of  FIG. 5 . As shown in  FIG. 8 , the inductor  7  includes a conductive winding module  2 ′ and a magnetic core assembly  8 . The magnetic core assembly  8  is penetrated through the channel  23  of the conductive winding module  2 ′ such that the magnetic core assembly  8  is sheathed by the conductive winding module  2 ′. When the pins  22  are soldered onto corresponding contact pads or conductive holes of a system circuit board (not shown), the inductor  7  is electrically connected with the system circuit board. 
     From the above embodiments, it is noted that the non-insulated winding structure may be produced according to diverse processes. For example, as shown in  FIGS. 2 and 4 , the conductive bodies of the non-insulated winding structure are combined together by a high-temperature welding process. Alternatively, the non-insulated winding structure is formed in a mold by an electroforming process as an integral structure, so that no welding seams are created. Alternatively, the non-insulated winding structure is fabricated by bending multiple copper plates as a multi-loop structure. For marking electrical connection between the magnetic element and the system circuit board, the pins are not covered with the insulating varnish layer. In a case that the non-insulated winding structure is fabricated by bending multiple copper plates, the insulating varnish layer may be previously formed on the whole flat metallic plate before the bending process. Since the non-insulated winding structure produced by the high-temperature welding process, the electroforming process or the bending process is very thin and the insulating varnish layer is relatively thinner than the insulating tape, the overall thickness of the magnetic element is reduced. 
     In the above embodiments, the insulating varnish layer is formed on the surfaces of the conductive bodies  21  by a mechanical process such as a powder coating process, a spray coating process or a dipping process. The mechanical process is very convenient and time-saving in comparison with the conventional method of attaching the insulating tapes. Moreover, since the insulating varnish layer is not easily scraped off the surfaces of the conductive bodies, the short-circuit problem is avoided. 
     From the above description, the method for fabricating the conductive winding module of the present invention includes a step of forming the insulating varnish layer on the conductive bodies after the non-insulated winding structure is provided. In comparison with the prior art wherein the insulating tapes are previously attached on the conductive bodies, the fabricating method of the present invention is simplified and cost-effective. Moreover, since the insulating varnish layer is substantially a thin film, the overall thickness of the conductive winding module of the present invention is reduced while maintaining a good electrical safety. 
     While the invention has been described in terms of what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention needs not be limited to the disclosed embodiment. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims which are to be accorded with the broadest interpretation so as to encompass all such modifications and similar structures.