Abstract:
A manufacturing method of an embedded inductor includes the steps of providing a magnetic plastic material, disposing at least one coil into a mold, and injecting or pressing the magnetic plastic material into the mold to form a magnetic body encapsulating the coil. An embedded inductor includes at least one magnetic body encapsulating the coil by injecting molding or pressing molding.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This Non-provisional application claims priority under 35 U.S.C. §119(a) on Patent Application No(s). 096110079 filed in Taiwan, Republic of China on Mar. 23, 2007, the entire contents of which are hereby incorporated by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of Invention 
         [0003]    The invention relates to an inductor and a manufacturing method thereof. In particular, the invention relates to an embedded inductor and the manufacturing method thereof. 
         [0004]    2. Related Art 
         [0005]    Technical progresses push electronic products toward the trend of miniaturization, low operating voltages and high operating currents. The basic and important elements such as the inductors are also requested to have lighter weight and smaller size in accordance with the miniaturization requirement. 
         [0006]    As shown in  FIG. 1 , the conventional EI-type inductor  1  comprises an E-type iron core  10 , a coil  11 , and an I-type iron core  12  stacked in sequence. The two pins  11   a  and  11   b  of the coil  11  are correspondingly bent to two preformed recessions  12   a  and  12   b  of the I-type iron core  12 , respectively. 
         [0007]    However, since the inductor  1  consists of several independent components packaged together, there are many air gaps inside it. The air gaps will lower the operating efficiency of the element and are not suitable for the miniaturization of the element. To provide an inductor that has the characteristic of large currents, high frequencies and low magnetic loss, the embedded inductor is introduced. As shown in  FIG. 2 , U.S. Pat. No. 6,204,744 discloses a manufacturing method of an embedded inductor including the following steps  81  to  89 . In step  81 , one end of a coil is soldered to a corresponding pin frame. In step  82 , the coil is wound. In step  83 , the other end of the coil is soldered onto the pin frame. In step  84 , the acetone solution is added. In step  85 , the coil is fixed. In step  86 , magnetic powders are formed by mixing first iron powders  861 , second iron powders  862 , a filler agent  863 , a resin  864  and a lubricant  865 . In step  87 , a mold is provided to perform a die casting process with the magnetic powders. In step  88 , the resin is cured by heating. In step  89 , the pins are cut and bent. 
         [0008]    U.S. Pat. No. 6,661,328 discloses another manufacturing method of an embedded inductor (not shown). The method includes the following steps. First, a mixture containing metal magnetic powders and resin is provided. The mixture is heated at a temperature between 65° C. and 200° C. Then, the mixture is granulated. The mixture is then die-casted to form a magnetic body that covers a coil. Finally, the magnetic body is heated to cure the resin. 
         [0009]    The related art employs the die casting and thermal curing method on magnetic powders to form the embedded inductor. However, this technique is not only slow in production, but it also cannot meet the miniaturization requirement due to some technical problems. Therefore, these methods are not ideal for manufacturing compact inductors. 
         [0010]    Therefore, it is an important subject to provide an embedded inductor, which has high operating efficiency and low magnetic loss, and can meet the miniaturization and high production rate requirements, and a manufacturing method thereof. 
       SUMMARY OF THE INVENTION 
       [0011]    In view of the foregoing, the invention is to provide an embedded inductor that has high operating efficiency and low magnetic loss, as well as meets the miniaturization and high production rate requirements. A corresponding manufacturing method of the embedded inductor is also disclosed. 
         [0012]    To achieve the above, the invention discloses a manufacturing method of an embedded inductor. The manufacturing method includes the steps of: providing at least one magnetic plastic material, providing at least one coil in a mold, and injecting or pressing the magnetic plastic material into the mold to form a magnetic body encapsulating the coil. 
         [0013]    To achieve the above, the invention also discloses an embedded inductor including a coil and at least one magnetic body. The magnetic body encapsulates the coil by injection or press molding. 
         [0014]    As mentioned above, the embedded inductor and the manufacturing method thereof of the invention inject or press a magnetic plastic material into a mold to encapsulate the coil disposed and positioned inside the mold, thereby forming a magnetic body. Therefore, by using the injection or press molding technique, the invention can simply manufacture miniaturized embedded inductors. With an appropriate mold design, the embedded inductors can be mass produced at a relatively short time. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    The invention will become more fully understood from the detailed description and accompanying drawings, which are given for illustration only, and thus are not limitative of the present invention, and wherein: 
           [0016]      FIG. 1  is a schematic illustration of a conventional inductor; 
           [0017]      FIG. 2  is a flow diagram of a conventional manufacturing method of the embedded inductor; 
           [0018]      FIG. 3  is a flow diagram of a manufacturing method of an embedded inductor according to an embodiment of the invention; and 
           [0019]      FIG. 4  is an exploded view of an embedded inductor according to the embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0020]    The present invention will be apparent from the following detailed description, which proceeds with reference to the accompanying drawings, wherein the same references relate to the same elements. 
         [0021]    With reference to  FIGS. 3 and 4 , a manufacturing method of an embedded inductor according to an embodiment of the invention includes step S 10 , step S 20  and step S 30 . In step S 10 , a magnetic plastic material is provided. In step S 20 , at least one coil C is provided. In step S 30 , the magnetic plastic material is injected or pressed into a mold  4  so that the magnetic plastic material encapsulates the coil C. 
         [0022]    In step S 10 , the magnetic plastic material is a uniform mixture of at least one type of magnetic powders and a resin with adding a small amount of coupling agent. The magnetic powder in this embodiment is iron (Fe), silicon (Si), cobalt (Co), nickel (Ni), aluminum (Al), molybdenum (Mo) or their mixtures. The resin can be a thermosetting resin, thermoplastic resin, or photosetting resin. Moreover, the thermoplastic resin can be polypropylene, polyphenylene sulfide (PPS) or Nylon. Moreover, Nylon can be Nylon 6, Nylon 12, or Nylon 66. The thermosetting resin can be epoxy or phenol. 
         [0023]    In step S 20 , the coil C is formed by winding a conductive wire several times. The conductive wire can be a round wire, square wire or flat wire. The coil C can have several ends, each of which can be directly used as a pin of the coil C. Alternatively, the end of the coil C may be externally connected with at least one conductive structure as the pin of the coil C. When an end of the coil C is directly used as a pin, the coil end or conductive structure preferably extends and protrudes from the magnetic body. 
         [0024]    In step S 30 , the mold  4  consists of at least two mold units  41  and  42 . The mold unit  41  includes at least an accommodating recess  411  and at least one flow channel  412  connected with the accommodating recess  411 . The coil C is disposed inside the accommodating recess  411 . The mold unit  41  or the mold unit  42  includes at least one hole  421  corresponding to the flow channel so that the magnetic plastic material can be injected. 
         [0025]    Moreover, the mold unit  42  also has a concave part  422  corresponding to the accommodating recess  411 . The combination of the accommodating recess  411  and the concave part  422  forms an accommodating space. Therefore, the magnetic plastic material can enter the accommodating space via the flow channel  412  to encapsulate the coil C. 
         [0026]    Furthermore, the mold units  41  and  42  can be positioned via a positioning structure  43 . The positioning structure  43  can be a pair of positioning pin  431  and positioning hole  432 , corresponding to the mold units  41  and  42 , respectively. Thus, the mold units  41 ,  42  can be readily positioned. 
         [0027]    Before step S 30 , there can be an additional step S 11  of preheating the mold  4  so that the magnetic plastic material can be easily filled into the mold  4 . If the magnetic plastic material is a thermosetting resin, the preheating temperature of the mold  4  is preferably between the curing temperature and the plasticizing temperature. If the magnetic plastic material is a thermoplastic resin, the preheating temperature of the mold  4  is preferably higher than the plasticizing temperature. 
         [0028]    Before step S 30 , there can also be an additional step S 21  of positioning the coil C in the mold  4 . The coil C is positioned inside the mold  4  using a positioning structure (not shown). Step S 21  can be performed while the coil C is disposed in the mold  4 . Step  21  can also be performed after the mold  4  is assembled. 
         [0029]    After step S 30 , there can be an additional step S 31  of curing the magnetic plastic material to render a magnetic body. The embedded inductor is obtained after removing the mold  4 . The method of curing the magnetic plastic material depends on the used material. It can be cooling (while the magnetic plastic material contains, for example, thermoplastic resin), heating (while the magnetic plastic material contains, for example, thermosetting resin) or illuminating with light (while the magnetic plastic material contains, for example, photosetting resin). 
         [0030]    After step S 31 , there can further be a cutting step to cut the magnetic body, the coil ends or the conductive structure so that the embedded inductor has a better and smoother shape. Moreover, a bending action can be performed so that the pins of the coil C bend toward a particular direction. In this case, the embedded inductor can be more easily connected with the system or other devices. 
         [0031]    To manufacture several embedded inductors at the same time, one can put multiple coils on at least one frame. At the same time, the mold is also provided with the same number of accommodating recesses corresponding to the coils to accommodate them. Therefore, a plurality of embedded inductors can be formed on the frame at the same time. Afterwards, the embedded inductors are departed from the frame by cutting. 
         [0032]    Another method of manufacturing multiple embedded inductors is to form a plurality of accommodating recesses on the mold, followed by disposing a coil in each of the accommodating recesses. The coils can be disposed in an array when the number of coils is equal to or greater than 2. This method can also form multiple embedded inductors simultaneously. 
         [0033]    In summary, the embedded inductor and the manufacturing method thereof of the invention inject or press a magnetic plastic material into a mold to encapsulate the coil disposed and positioned inside the mold, thereby forming a magnetic body. Therefore, by using the injection or press molding technique, the invention can simply manufacture miniaturized embedded inductors. With an appropriate mold design, the embedded inductors can be mass produced at a relatively short time. 
         [0034]    Although the invention has been described with reference to specific embodiments, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as alternative embodiments, will be apparent to persons skilled in the art. It is, therefore, contemplated that the appended claims will cover all modifications that fall within the true scope of the invention.