Abstract:
There is provided an electronic device. The electronic device includes: a wiring board; a first electronic component mounted on the wiring board and configured to emit an electromagnetic wave having a first frequency band; a second electronic component mounted on the wiring board and configured to emit an electromagnetic wave having a second frequency band; a first magnetic thin film covering the wiring board, the first electronic component and the second electronic component, wherein the first magnetic thin film has a composition corresponding to the first frequency band; and a second magnetic thin film covering the first magnetic thin film, wherein the second magnetic thin film has a composition corresponding to the second frequency band.

Description:
[0001]    This application claims priority from Japanese Patent Application No. 2013-037549, filed on Feb. 27, 2013, the entire contents of which are herein incorporated by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Technical Field 
         [0003]    The present disclosure relates to an electronic device. 
         [0004]    2. Description of the Related Art 
         [0005]    An electronic device including a plurality of electronic components which are mounted on a wiring board has been known. The electronic components are configured to emit electromagnetic waves according to their operations. In addition, the electronic components are affected by electromagnetic waves coming from the outside. As a method for preventing release and penetration of the electromagnetic waves, it can be considered, for example, to form a ferrite film or the like, to fix a shield case made of metal to the wiring board (see WO2005/081609, for example). 
         [0006]    By the way, in some cases, the electronic components for various kinds of electronic circuits are mounted on the wiring board. Therefore, it is desired to suppress influences of electromagnetic waves emitted from the various kinds of electronic circuits. 
       SUMMARY OF THE INVENTION 
       [0007]    According to one or more aspects of the present invention, there is provided an electronic device. The electronic device includes: a wiring board; a first electronic component mounted on the wiring board and configured to emit an electromagnetic wave having a first frequency band; a second electronic component mounted on the wiring board and configured to emit an electromagnetic wave having a second frequency band; a first magnetic thin film covering the wiring board, the first electronic component and the second electronic component, wherein the first magnetic thin film has a composition corresponding to the first frequency band; and a second magnetic thin film covering the first magnetic thin film, wherein the second magnetic thin film has a composition corresponding to the second frequency band. 
         [0008]    According to one aspect of the invention, it is possible to suppress influences of the electromagnetic waves on the electronic components which are mounted on the wiring board. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1A  and  FIG. 1B  are schematic perspective views of an electronic device according to a first embodiment of the present invention; 
           [0010]      FIG. 2  is a schematic sectional view of the electronic device according to the first embodiment; 
           [0011]      FIG. 3  is a graph showing properties of magnetic thin films; 
           [0012]      FIG. 4  is a schematic sectional view of an electronic device according to a modification of the first embodiment; 
           [0013]      FIG. 5  is a schematic sectional view of an electronic device according to another modification of the first embodiment; 
           [0014]      FIG. 6  is a schematic sectional view of an electronic device according to a second embodiment of the present invention; and 
           [0015]      FIG. 7  is a schematic sectional view of an electronic device according to a modification of the second embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0016]    Embodiments of the invention will be now described referring to the attached drawings. 
         [0017]    It should be noted that the attached drawings are shown in a partially enlarged scale, in some cases, and sizes, ratios, etc. in the drawings are sometimes different from actual ones. Moreover, in the sectional views, hatchings are partly omitted for better understanding of sectional structures of respective members. 
       First Embodiment 
       [0018]    As shown in  FIG. 1A , a plurality of electronic components  12   a  to  12   f  are mounted on one main face  11   a  of a wiring board  11  of an electronic device  10 . The electronic components  12   a  to  12   e  are connected to pads (not shown) on the wiring board  11 . The electronic components  12   a  to  12   c  are, for example, semiconductor integrated circuits (LSI). For example, the electronic components  12   d ,  12   e  are resistors, condensers or coils. The electronic component  12   f  is an antenna to be used for wireless communication, for example. This electronic component  12   f  is, for example, a wiring pattern on the one main face  11   a  of the wiring board  11 . 
         [0019]    As shown in  FIG. 1B , a portion of the one main face  11   a  of the wiring board  11  and the electronic components  12   a  to  12   e  are covered with a magnetic film  13 . The magnetic film  13  is configured to shield or attenuate electromagnetic waves at frequencies corresponding to the electronic components  12   a  to  12   e  which are mounted on the wiring board  11 . Thus, the magnetic film  13  reduces an amount of the electromagnetic waves, which are generated by operations of the electronic components  12   a  to  12   e  and irradiated to the outside. Moreover, the magnetic film  13  reduces an amount of the electromagnetic waves, which come from the outside and affect the electronic components  12   a  to  12   e , that is, an amount of the electromagnetic waves reaching the electronic circuit, as compared with a case where the magnetic film  13  is not used. 
         [0020]    Moreover, the magnetic film  13  shields or attenuates the electromagnetic waves. Therefore, the electronic component  12   f  which serves as the antenna for the wireless communication is not covered with the magnetic film  13 . 
         [0021]    Then, an example of the electronic device will be now described. In the following description, parts of the elements as shown in  FIGS. 1A and 1B  are denoted with the same reference numerals. 
         [0022]    As shown in  FIG. 2 , the wiring board  11  of the electronic device  10  has a board body  21 . Material for the board body  21  is, insulating resin such as glass epoxy resin, ceramics, silicone, or pre-preg material, for example. Moreover, the board body  21  may be formed as a multi-layered wiring board. 
         [0023]    Mounting pads  22  are formed on a first main face (an upper face in  FIG. 2 ) of the board body  21 . Each of the mounting pads  22  includes a plurality of (three in  FIG. 2 ) metal layers  22   a  to  22   c , which are formed in this order on the first main face of the board body  21 . The metal layer  22   a  is made of copper, for example. The metal layer  22   b  is made of nickel (Ni), for example. The metal layer  22   c  is made of gold (Au), for example. The metal layer  22   a  is a part of a wiring pattern which is formed on the first main face of the board body  21 , and is exposed from an opening which is formed in a solder resist  23  covering this wiring pattern and the first main face of the wiring board  21 . The metal layers  22   b ,  22   c  are plating layers which are formed on an upper face of the metal layer  22   a . In  FIG. 2 , parts of the wiring pattern except the mounting pads  22  (a region covered with the solder resist  23 ) are not shown. The solder resist  23  is resin such as epoxy, polyester or the like. The number of the metal layers in the mounting pad  22  may be appropriately changed. Moreover, palladium (Pd), silver (Ag), Pd alloy, Au alloy, Ni alloy, Ag alloy, etc. may be used as the material for the metal layers  22   b  and  22   c.    
         [0024]    A wiring pattern  24  is formed on a second main face (a lower face in  FIG. 2 ) of the board body  21 . The wiring pattern  24  is electrically connected to the wiring pattern which is formed on the first main face through via holes (not shown). The via holes are through-hole via holes or stack via holes. This wiring pattern  24  and the second main face of the board body  21  are covered with a solder resist  25 . The wiring pattern  24  is formed of copper, for example. The solder resist  25  is resin such as epoxy, polyester, for example. 
         [0025]    The electronic device  10  includes a power supply circuit  31 , a control circuit  32 , and a high frequency circuit  33 . The power supply circuit  31  includes a semiconductor device  31   a  and a chip component  31   b  which are mounted on the wiring board  11 . The semiconductor device  31   a  and the single chip component  31   b  in the power supply circuit  31  are shown as a single one in  FIG. 2 . A package shape of the semiconductor device  31   a  is QFP, for example, and leads of the semiconductor device  31   a  are connected to the mounting pads  22  by soldering (not shown). The chip component  31   b  is, for example, a resistor, a condenser, a coil, a diode or the like, and connected to the mounting pad  22  by soldering (not shown). 
         [0026]    Similarly, the control circuit  32  includes a semiconductor device  32   a  and a chip component  32   b  which are mounted on the wiring board  11 . Moreover, the high frequency circuit  33  includes a semiconductor device  33   a  and a chip component  33   b  which are mounted on the wiring board  11 . Single semiconductor devices  32   a ,  33   a  and single chip components  32   b ,  33   b  which are included in the control circuit  32  and the high frequency circuit  33  are shown in  FIG. 2 . 
         [0027]    Package shapes of the semiconductor devices  31   a  to  33   a  as shown in  FIG. 2  may be, for example, DIP, SOP, BGA and so on. Moreover, passive elements such as the resistor and condenser may be formed as the components having leads. 
         [0028]    The power supply circuit  31  includes, for example, a DC-DC converter, and generates power supply voltage to be supplied to the high frequency circuit  33 . The control circuit  32  includes, for example, a CPU, and a signal generating circuit which generates clock signals for operating the circuit sections  31  to  33 , and controls the power supply circuit  31  and the high frequency circuit  33 . The high frequency circuit  33  includes, for example, a receiving circuit and a transmitting circuit for wireless communication. 
         [0029]    A magnetic film  13   a  is formed on the upper face of the wiring board  11 . The respective semiconductor devices  31   a  to  33   a  and the chip components  31   b  to  33   b  are covered with the magnetic film  13   a . The magnetic film  13   a  includes a plurality of layers (two layers in  FIG. 2 ) of magnetic thin films  41   a ,  42   a . The magnetic thin film  41   a  is formed to cover the upper face of the wiring board  11 , surfaces of the semiconductor devices  31   a  to  33   a , and surfaces of the chip components  31   b  to  33   b . The magnetic thin film  42   a  is formed to cover a surface of the magnetic thin film  41   a.    
         [0030]    Although the magnetic thin films  41   a ,  42   a  are shown, in  FIG. 2 , as having larger thicknesses than their actual thicknesses for easy understanding, the actual thicknesses of the magnetic thin films  41   a ,  42   a  are 1 to 3 μm, for example. Therefore, the magnetic thin film  41   a  and the magnetic thin film  42   a  are present between the semiconductor device  31   a  and the chip component  31   b  of the power supply circuit  31  and between the semiconductor device  32   a  and the chip component  32   b  of the control circuit  32 , in a direction along the surface of the wiring board  11 . Also, the magnetic thin film  41   a  and the magnetic thin film  42   a  are present between the semiconductor device  32   a  and the chip component  32   b  of the control circuit  32  and between the semiconductor device  33   a  and the chip component  33   b  of the high frequency circuit  33 , in the direction along the surface of the wiring board  11 . 
         [0031]    A magnetic film  13   b  which covers the lower face of the wiring board  11  includes magnetic thin films  41   b ,  42   b . These magnetic thin films  41   b ,  42   b  are formed in this order on the lower face of the wiring board  11 . A thickness of the magnetic thin films  41   b ,  42   b  is 1 to 3 μm, for example. 
         [0032]    The magnetic thin films  41   a ,  41   b  are formed of ferrite containing nickel (Ni) and zinc (Zn), for example, which are sometimes called as Ni—Zn ferrite films, in the following description. The magnetic thin films  42   a ,  42   b  are formed of ferrite containing manganese (Mn) and zinc (Zn), for example, which are sometimes called as Mn—Zn ferrite films, in the following description. 
         [0033]    In this embodiment, types and ratios of the metals which are contained in the magnetic thin films  41   a ,  42   a ,  41   b ,  42   b  are determined according to the circuits  31  to  33 . Composition of the magnetic thin films  41   a ,  41   b  (the Ni—Zn ferrite film) is determined according to the control circuit  32  and the high frequency circuit  33 . Composition of the magnetic thin films  42   a ,  42   b  (the Mn—Zn ferrite film) is determined according to the power supply circuit  31  and the high frequency circuit  33 . 
         [0034]    The magnetic thin films  41   a ,  41   b ,  42   a ,  42   b  are formed, for example, by spin spraying method. Therefore, the magnetic thin film  41   a  is formed to fill gaps between the semiconductor devices  31   a  to  33   a  and the wiring board  11 . 
         [0035]    Plasma treatment is performed after the magnetic thin film  41   a  is formed, and then the magnetic thin film  42   a  is formed after this plasma treatment. In the plasma treatment, an OH radical is provided on a surface of the magnetic thin film  41   a . Metal ion contained in a reaction solution which is used in the spin spraying method is coupled to the OH radical on the surface of the magnetic thin film  42   a . In this manner, high adhesion can be obtained between the magnetic thin film  41   a  and the magnetic thin film  42   a . In the same manner, plasma treatment is performed after the magnetic thin film  41   b  is formed, and then the magnetic thin film  42   b  is formed after this plasma treatment. In this manner, high adhesion can be obtained between the magnetic thin film  41   b  and the magnetic thin film  42   b . The plasma treatment may be performed before the magnetic thin films  41   a ,  41   b  are formed. In this case, the OH radical is provided on an exposed face of the wiring board  11 , the surfaces of the semiconductor devices  31   a  to  33   a  and surfaces of the chip components  31   b  to  33   b  during the plasma treatment. Thus, it is possible to enhance the adhesion of the magnetic thin films  41   a ,  41   b.    
         [0036]    Complex permeability μ of the magnetic material (ferrite) which is energized by alternating current is represented by a formula μ=μ′−jμ″. 
         [0037]    An imaginary part μ″ is a magnetic loss part which is necessary for absorbing electromagnetic waves. The magnetic material converts the electromagnetic waves in a frequency band corresponding to a resonance frequency into thermal energy due to magnetic loss property. The resonance frequency of ferrite corresponds to composition of ferrite. Therefore, it is possible to adjust the resonance frequency to a desired value, by appropriately changing the composition of ferrite. Then, by using ferrite having this composition, it is possible to decrease the intensity of the electromagnetic waves passing through ferrite in a frequency band corresponding to the resonance frequency. 
         [0038]    Basic composition of ferrite is M.Fe 3 O 4 , where M is a bivalent metal ion. Ferrite of this type is called as spinel ferrite. The bivalent metal ion includes, for example, manganese (Mn), zinc (Zn), nickel (Ni), magnesium (Mg), cobalt (Co), and copper (Cu). The properties of ferrite depend on types and ratios of at least one kind of metal ions which are contained in M. 
         [0039]    For example, ferrite (Zn ferrite) containing zinc (Zn) is an anti-ferro-magnetic material, and does not have ferro-magnetic property. However, when zinc is added to ferrite containing other metals, polygenetic ferrite is composed and the magnetism is enhanced (saturated magnetic flux density is increased). Moreover, when zinc (ZN) is added, ferrite is soft magnetized. 
         [0040]    The complex permeability and resonance frequency of ferrite vary according to added content of zinc (Zn) or cobalt (Co). For example, by increasing the content of zinc, the complex permeability is enhanced, and the resonance frequency of the complex permeability is lowered. On the other hand, by decreasing the content of zinc, the complex permeability is lowered, and the resonance frequency of the complex permeability is enhanced. Moreover, by increasing the content of cobalt, the complex permeability is enhanced, and the resonance frequency of the complex permeability is enhanced. 
         [0041]      FIG. 3  shows an example of frequency characteristics of complex permeability of the Ni—Zn ferrite film and the Mn—Zn ferrite film. In  FIG. 3 , a solid line L 11  represents a real part μ′ of the complex permeability of the Mn—Zn ferrite film, and a dotted line L 12  represents an imaginary part μ″ of the complex permeability of the Mn—Zn ferrite film. Moreover, a solid line L 21  represents a real part μ′ of the complex permeability of the Ni—Zn ferrite film, and a dotted line L 22  represents an imaginary part μ″ of the complex permeability of the Ni—Zn ferrite film. 
         [0042]    For example, the resonance frequency of the Ni—Zn ferrite film is several GHz. Moreover, the Ni—Zn ferrite film has resistivity of about 1×10 6  (Ω·m), and can be treated as an electrical insulator. For example, the resonance frequency of the Mn—Zn-ferrite film is several MHz, and its resistivity is about 1 to 10 (Ω·m). 
         [0043]    Now, the operation of the electronic device  10  will be now described. 
         [0044]    In this embodiment, the control circuit  32  includes logic circuits such as a CPU, as described above. These circuits switch on or off transistors at the frequencies according to operating clock signals. Therefore, high frequency noises are emitted by the operation. The composition of the magnetic thin films  41   a ,  41   b  is determined according to the frequencies of the noises which are emitted from this control circuit  32 . Accordingly, the magnetic thin films  41   a ,  41   b  decrease an amount of the high frequency noises which are emitted from the control circuit  32  to the outside. In addition, the magnetic thin films  41   a ,  41   b  decrease an amount of electromagnetic waves having the high frequencies which intrude into the signals of the control circuit  32  from the outside. 
         [0045]    As described above, the power supply circuit  31  emits low frequency noises according to the operation of the circuit for generating the power supply voltage (a DC-DC converter, for example). The composition of the magnetic thin film  42   a ,  42   b  is determined according to frequencies of the noises which are emitted from this power supply circuit  31 . Therefore, the magnetic thin films  42   a ,  42   b  decrease an amount of the low frequency noises which are emitted from the power supply circuit  31  to the outside. In addition, the magnetic thin films  42   a ,  42   b  decrease an amount of electromagnetic waves having the low frequency which intrude into the signals of the power supply circuit  31  from the outside. 
         [0046]    Moreover, the electronic device  10  has the high frequency circuit  33 , and the semiconductor device  33   a  and chip component  33   b  which are included in the high frequency circuit  33  are mounted on the wiring board  11 . These semiconductor device  33   a  and chip component  33   b  are covered with the magnetic thin films  41   a ,  41   b  and the magnetic thin films  42   a ,  42   b.    
         [0047]    The magnetic thin films  41   a  to  42   b  suppress transmission of electromagnetic waves in frequency bands corresponding to their respective compositions. Therefore, the magnetic thin films  41   a  to  42   b  suppress intrusion of the electromagnetic waves (noises) in the frequency bands corresponding to their respective compositions. 
         [0048]    The composition of the magnetic thin films  41   a ,  41   b  is determined according to the control circuit  32 . A frequency band of the imaginary part μ″ in the complex permeability μ of the magnetic thin films  41   a ,  41   b  corresponds to the high frequency noises which are generated in the control circuit  32 . Therefore, the magnetic thin films  41   a ,  41   b  suppress the high frequency noises which are emitted from the control circuit  32  to the outside and intrude into the high frequency circuit  33 . 
         [0049]    Likewise, the composition of the magnetic thin films  42   a ,  42   b  is determined according to the power supply circuit  31 . A frequency band of the imaginary part μ″ in the complex permeability μ of the magnetic thin films  42   a ,  42   b  corresponds to the low frequency noises which are generated in the power supply circuit  31 . Therefore, the magnetic thin films  42   a ,  42   b  suppress the low frequency noises which are emitted from the power supply circuit  31  to the outside and intrude into the high frequency circuit  33 . 
         [0050]    As described above, the following advantages can be obtained according to this embodiment. 
         [0051]    (1-1) The semiconductor device  31   a  and the chip component  31   b  of the power supply circuit  31 , and the semiconductor device  32   a  and the chip component  32   b  of the control circuit  32  are mounted on the wiring board  11  of the electronic device  10 . The surface of the wiring board  11 , the surfaces of the semiconductor devices  31   a ,  32   a , and the surfaces of the chip components  31   b ,  32   b  are covered with the magnetic film  13   a . The magnetic film  13   a  includes the two magnetic thin films  41   a ,  41   b . The composition of the magnetic thin film  41   a  (the Ni—Zn ferrite film) is set according to the control circuit  32  and the high frequency circuit  33 . The composition of the magnetic thin film  42   a  (the Mn—Zn ferrite film) is set according to the power supply circuit  31  and the high frequency circuit  33 . The magnetic thin film  41   a  decreases the electromagnetic waves having the frequency according to the control circuit  32 . The magnetic thin film  42   a  decreases the electromagnetic waves having the frequency corresponding to the power supply circuit  31 . Moreover, the magnetic thin films  41   a ,  42   a  suppress transmission of the electromagnetic waves in the frequency bands corresponding to their respective compositions. Accordingly, the magnetic film  13   a  including the magnetic thin films  41   a ,  42   a  can suppress emission of the electromagnetic waves in the different frequency bands which are generated in the power supply circuit  31  and the control circuit  32 . 
         [0052]    (1-2) The semiconductor device  33   a  and the chip component  33   b  of the high frequency circuit  33  are mounted on the wiring board  11 . The surface of the semiconductor device  33   a  and the surface of the chip component  33   b  are covered with the magnetic film  13   a  including the magnetic thin films  41   a  and  42   a . Therefore, the magnetic thin films  41   a  and  42   a  can suppress influences of the electromagnetic waves (noises) according to their respective compositions, on the high frequency circuit  33 . 
         [0053]    (1-3) The wiring board  11  and the electronic components (the semiconductor devices  31   a  to  33   a  and the chip components  31   b  to  33   b ) are covered with the magnetic film  13   a  including the magnetic thin films  41   a  and  42   a . The thickness of the magnetic thin films  41   a  and  42   a  is 1 to 3 μm. Therefore, it is possible to restrain upsizing of the electronic device  10 , as compared with a case where a shield case made of metal or a sheet-like magnetic material is used. 
       (Modification) 
       [0054]    The above described embodiment may be modified in the following manner. 
         [0055]    As shown in  FIG. 4 , a magnetic film  51   a  of an electronic device  50  includes the magnetic thin films  41   a ,  42   a , and an insulating film  52   a . The magnetic thin film  41   a , the insulating film  52   a , and the magnetic thin film  42   a  are formed in this order, from the first main face of the wiring board  11  (the face where the electronic components in the respective circuit sections  31  to  33  are mounted) and the surfaces of the electronic components (the semiconductor devices  31   a  to  33   a  and the chip components  31   b  to  33   b ). 
         [0056]    Likewise, a magnetic film  51   b  on the second main face of the wiring board  11  (a lower face in  FIG. 4 , which is a non-mounting face) includes the magnetic thin films  41   b ,  42   b , and an insulating film  52   b.    
         [0057]    The insulating films  52   a ,  52   b  are formed of insulating resin such as epoxy group resin having good adhesion. 
         [0058]    A resin such as polyimide group resin may be used as material for the insulating films  52   a ,  52   b . Moreover, as the material for the insulating films  52   a ,  52   b , a sheet-like insulating resin in a B stage (in a half-hardened state) having high viscosity (NCF (Non Conductive Film), for example) or a paste-like insulating resin (NCP (Non Conductive Paste), for example) can be used. It is also possible to use the materials which are different from each other, as the materials for the insulating films  52   a ,  52   b.    
         [0059]    The insulating film  52   a  is formed of the resin having good adhesion. Therefore, it is possible to restrain removal of the magnetic thin films  41   a ,  42   a . Similarly, the insulating film  52   b  is formed of the resin having good adhesion. Therefore, it is possible to restrain removal of the magnetic thin films  41   b ,  42   b.    
         [0060]    As shown in  FIG. 5 , a magnetic film  61   a  of an electronic device  60  includes the magnetic thin films  41   a ,  42   a , and insulating films  52   a ,  62   a . The insulating film  62   a , the magnetic thin film  42   a , the insulating film  52   a , and the magnetic thin film  41   a  are formed in this order, from the first main face of the wiring board  11  (the face where the electronic components in the circuit sections  31  to  33  are mounted) and the surfaces of the electronic components (the semiconductor devices  31  to  33   a  and the chip components  31   b  to  33   b ). 
         [0061]    Likewise, a magnetic film  61   b  on the second main face of the wiring board  11  (a lower face in  FIG. 5 , which is a non-mounting face) includes the magnetic thin films  41   b ,  42   b , and insulating films  52   b ,  62   b.    
         [0062]    The insulating films  62   a ,  62   b  are formed of insulating resin such as epoxy group resin having good adhesion. A resin such as polyimide group resin may be used as material for the insulating films  62   a ,  62   b . Moreover, as the material for the insulating films  62   a ,  62   b , a sheet-like insulating resin in a B stage (in a half-hardened state) having high viscosity (NCF (Non Conductive Film), for example) or a paste-like insulating resin (NCP (Non Conductive Paste), for example) can be used. Moreover, as the material for the insulating films  62   a ,  62   b , Parylene (paraxylene-based polymers) can be used. Parylene can be formed by chemical vapor deposition (CVD) method, for example. By employing Parylene as the material for the insulating films  62   a ,  62   b , it is possible to surely protect the wiring board  11  due to the high electrical insulation property and the mechanical durability of Parylene. Further, since the insulating films  62   a ,  62   b  that are formed of Parylene can be formed on the first and second main faces of the wiring board  11  such that the thicknesses of the insulating films  62   a ,  62   b  are small and uniform over the wiring board  11 , a distance between the magnetic thin film  42   a  and the power supply circuit  31  or a distance between the magnetic thin film  42   a  and the high frequency circuit  33  can be made small and kept uniform, which contributes to the improvement in noise reduction. Still further, the insulating films  62   a ,  62   b  that are formed of Parylene can be formed to cover the circuits  31  to  33  without any gap therebetween, and thus the insulating films  62   a ,  62   b  are never expanded and exploded in a secondary mounting using a reflow furnace. 
         [0063]    It is also possible to use materials which are different from each other, as the materials for the insulating films  62   a ,  62   b.    
         [0064]    The magnetic thin film  42   a  is, for example, the Mn—Zn ferrite film. Resistivity of the Mn—Zn ferrite film is lower than resistivity of the Ni—Zn ferrite film (the magnetic thin film  41   a ). The Ni—Zn ferrite film having the high resistivity can be treated in the same manner as an electric insulator. For this reason, it is possible for the Ni—Zn ferrite film to directly cover the semiconductor devices  31   a  to  33   a  and the chip components  31   b  to  33   b , as shown in  FIG. 1 . On the other hand, in case where the semiconductor devices  31   a  to  33   a  and the chip components  31   b  to  33   b  are directly covered with the Mn—Zn ferrite film having the low resistivity, bad insulation may be incurred. In this view, the semiconductor devices  31   a  to  33   a  and the chip components  31   b  to  33   b  are covered with the insulating film  62   a , as shown in  FIG. 5 , and then, the magnetic thin film  42   a  (the Mn—Zn ferrite film) is formed to cover this insulating film  62   a . By covering the surface of the wiring board  11  and the electronic components (the semiconductor devices  31   a  to  33   a  and the chip components  31   b  to  33   b ) with the insulating film  62   a  in this manner, restrictions due to the properties of the magnetic thin films  41   a ,  42   a  are eliminated, and it is possible to enhance freeness in changing order of working steps for forming the magnetic thin films  41   a ,  42   a.    
         [0065]    In  FIG. 5 , a wiring pattern  24  which is formed on the lower face of the board body  21  is covered with a solder resist  25 . Therefore, it is possible to omit the insulating film  62   b  on the lower face side of the wiring board  11 . Moreover, in the magnetic film  61   a  as shown in  FIG. 5 , the insulating film  52   a  between the magnetic thin film  42   a  and the magnetic thin film  41   a  may be omitted. In the same manner, in the magnetic film  61   b , the insulating film  52   b  between the magnetic thin film  42   b  and the magnetic thin film  41   b  may be omitted. 
       Second Embodiment 
       [0066]    As shown in  FIG. 6 , an electronic device  70  has a plurality of (six, in  FIG. 6 ) semiconductor packages  100 ,  200 ,  300 . The semiconductor package  100  is connected to the semiconductor package  200  by way of solder balls  71 , and the semiconductor package  200  is connected to the semiconductor package  300  by way of solder balls  72 . The solder balls  71 ,  72  are one example of connecting members. The solder balls  71 ,  72  are the solder balls each including a core formed of metal, for example, and this metal is, for example, copper. It is also possible to form each of the solder balls  71 ,  72  as one including a resin core or one including no core. 
         [0067]    A wiring board  110  of the semiconductor package  100  has a board body  121 . The board body  121  is made of insulating resin such as glass epoxy resin, ceramics, silicone, or prepreg material. It is also possible to form the board body  121  as a multi-layered wiring board. 
         [0068]    Mounting pads  122  and connecting pads  123  are formed on a first main face (an upper face in  FIG. 6 ) of the board body  121 . The mounting pads  122  and the connecting pads  123  are formed in the same manner as the mounting pads  22  in the first embodiment, as shown in  FIG. 2 . Each of the mounting pads  122  and the connecting pads  123  includes a part of a wiring pattern which is exposed from an opening of a solder resist  124 , and a plurality of metal layers which are formed on an upper face of the part. 
         [0069]    Wiring patterns  125  and mounting pads  126  are formed on a second main face (a lower face in  FIG. 6 ) of the board body  121 . The mounting pads  126  are formed in the same manner as the mounting pads  122 . Specifically, the mounting pads  126  includes a part of the wiring pattern  125  which is exposed from an opening of a solder resist  127 , and a plurality of metal layers which are formed on the part. In  FIG. 6 , the mounting pads  126  and the wiring patterns  125  are shown as separated from each other. The wiring patterns  125  are electrically connected to the wiring patterns on the upper face of the board body  121  by way of via holes which are not shown. The via holes are through-hole via holes or stack via holes. 
         [0070]    A semiconductor device  131  and a secondary battery  132  are mounted on the first main face (the upper face) of the wiring board  110 . The semiconductor device  131  is an electronic component included in the power supply circuit, and a representative of the electronic components which are included in the power supply circuit. A package shape of the semiconductor device  131  is, for example, QFP, and leads of the semiconductor device  131  are connected to the mounting pads  122 . The secondary battery  132  is connected to the mounting pads  122  by way of wires  133 . The power supply circuit controls electric charging of the secondary battery  132 . Moreover, the power supply circuit includes a DC-DC converter, for example, and generates power supply voltage to be supplied to the control circuit, the high frequency circuit, and a sensor circuit which will be described below, based on an electric power stored in the secondary battery. 
         [0071]    A connecting connector  141  is mounted on the mounting pads  126 . The connecting connector  141  is used for transmitting or receiving signals between this electronic device  70  and the other electronic devices, for supplying electric power for charging the secondary battery  132  and so on. 
         [0072]    The semiconductor package  100  has a magnetic film  150 . The magnetic film  150  is formed to cover a surface of the wiring board  110 , a surface of the semiconductor device  131 , and a surface of the secondary battery  132 , except a region required for connecting the solder balls  71  and the connecting connector  141 . The magnetic film  150  includes magnetic thin films  151 ,  152 . The magnetic thin film  151  is, for example, a Ni—Zn ferrite film, and the magnetic thin film  152  is, for example, a Mn—Zn ferrite film. The magnetic thin films  151 ,  152  are formed, for example, by spin spraying method in the same manner as in the above described embodiment. 
         [0073]    A wiring board  210  of the semiconductor package  200  has a board body  221 , in the same manner as the wiring board  110  of the semiconductor package  100 , and mounting pads  222  and connecting pads  223  are formed on a first main face (an upper face in  FIG. 6 ) of this board body  221 . The mounting pads  222  and connecting pads  223  are formed in the same manner as the mounting pads  122  and connecting pads  123  of the wiring board  110 . Specifically, each of the mounting pads  222  and the connecting pads  223  includes a part of a wiring pattern which is exposed from an opening of a solder resist  224 , and a plurality of metal layers which are formed on an upper face of the part. Wiring patterns  225  and mounting pads  226  are formed on a second main face (a lower face in  FIG. 6 ) of the board body  221 . The wiring patterns  225  are formed in the same manner as the wiring patterns  125  of the wiring board  110 . The connecting pads  226  are formed in the same manner as the connecting pads  223 . Each of the connecting pads  226  includes a part of the wiring pattern which is exposed from an opening of a solder resist  227 , and a plurality of metal layers which are formed on the part. 
         [0074]    Semiconductor devices  231 ,  232  are mounted on the first main face (the upper face) of the wiring board  210 . The semiconductor devices  231 ,  232  respectively have leads which are connected to the mounting pads  222  by means of solders (not shown). The semiconductor device  231  is an electronic component included in the control circuit, for example, and a representative of the electronic components included in the control circuit. The semiconductor device  232  is an electronic component included in the high frequency circuit, for example, and a representative of the electronic components included in the high frequency circuit. The control circuit includes, a CPU, and a signal generating circuit for generating clock signals for operating the respective circuit sections, and controls the power supply circuit, high frequency circuit, and sensor circuit. The high frequency circuit includes a receiving circuit and a transmitting circuit for wireless communication, for example. 
         [0075]    The semiconductor package  200  has a magnetic film  250 . The magnetic film  250  is formed to cover a surface of the wiring board  210 , surfaces of the semiconductor devices  231 ,  232 , except regions required for connecting the solder balls  71 ,  72 . The magnetic film  250  includes magnetic thin films  251 ,  252 . The magnetic thin film  251  is, for example, a Ni—Zn ferrite film, and the magnetic thin film  252  is, for example, a Mn—Zn ferrite film. 
         [0076]    A wiring board  310  of the semiconductor package  300  has a board body  321 , in the same manner as the wiring boards  110 ,  210 , and mounting pads  322  and an electronic component  331  are formed on a first main face (an upper face in  FIG. 6 ) of this board body  321 . The electronic component  331  serves as an antenna for wireless communication, for example. The mounting pads  322  are formed in the same manner as the mounting pads  222  of the wiring board  210 . Each of the mounting pads  322  includes a part of a wiring pattern (not shown) which is exposed from an opening of a solder resist  324 , and a plurality of metal layers which are formed on the part. The electronic component  331  is formed of a wiring pattern, and connected to the semiconductor device  232  in the high frequency circuit of the semiconductor package  200  by way of via holes (not shown), the wiring pattern, the solder ball  72 , and so on. 
         [0077]    Wiring patterns  325  and connecting pads  326  are formed on a second main face (a lower face in  FIG. 6 ) of the board body  321 . The wiring patterns  325  are formed in the same manner as the wiring patterns  225  of the wiring board  210 . The connecting pads  326  are formed in the same manner as the connecting pads  226  of the wiring board  210 . Specifically, each of the connecting pads  326  includes a part of a wiring pattern which is exposed from an opening of a solder resist  327 , and a plurality of metal layers which are formed on the part. 
         [0078]    The semiconductor package  300  has a magnetic film  350 . The magnetic film  350  is formed to cover a surface of the wiring board  310  and a surface of the semiconductor device  332 , except a region required for connecting the solder balls  72  and a region of a solder resist  324  for covering the electronic component  331 . The magnetic film  350  includes magnetic thin films  351 ,  352 . The magnetic thin film  351  is, for example, a Ni—Zn ferrite film. The magnetic thin film  352  is, for example, a Mn—Zn ferrite film. 
         [0079]    Then, operation of this electronic device  70  will be now described. 
         [0080]    The semiconductor packages  100  to  300  which are included in the electronic device  70  have the magnetic films  150 ,  250 ,  350  for covering the surfaces of the wiring boards  110 ,  210 ,  310 , and the semiconductor devices  131 ,  231 ,  232 ,  332 . The magnetic films  150 ,  250 ,  350  have the magnetic thin films  151 ,  152 ,  251 ,  252 ,  351 ,  352  in which the frequency bands of the imaginary part μ″ of the complex permeability are determined according to the control circuit, the high frequency circuit, and the power supply circuit. Thus, an amount of high frequency noises, which are generated in the control circuit (the semiconductor device  231 ) and the high frequency circuit (the semiconductor device  232 ) and emitted to the outside, is decreased. Moreover, an amount of low frequency noises, which are generated in the power supply circuit (the semiconductor device  131 ) and emitted to the outside, is decreased. Further, an amount of electromagnetic noises intruding into the respective circuits from the outside is decreased. 
         [0081]    The magnetic thin films  151 ,  152 ,  251 ,  252 ,  351 ,  352  have a thickness of, for example, 1 to 3 μm, and are tightly adhered to the surfaces of the wiring boards  110  to  310  and the surfaces of the electronic components (the semiconductor devices  131  to  332  and the secondary battery  132 ). For this reason, it is possible to downsize the electronic device  70 , as compared with a case where a shield case formed of metal or a sheet-like magnetic material (a ferrite sheet) is used. For example, in case where the shield case formed of metal or the sheet-like magnetic material is used, it is necessary to set large intervals between the respective semiconductor packages  100  to  300 . Accordingly, the sizes and pitches of the solder balls  71 ,  72  for connecting the semiconductor packages  100  to  300  are made larger. Moreover, because the shield case is fixed to the wiring board, the electronic components cannot be mounted in this region. As a result, arrangement pitches of the solder balls are made larger, which results in upsizing of the electronic device. 
         [0082]    As described hereinabove, the following advantages can be obtained according to this embodiment. 
         [0083]    (2-1) The semiconductor packages  100  to  300  have the magnetic films  150 ,  250 ,  350  for covering the surfaces of the wiring boards  110 ,  210 ,  310 , and the semiconductor devices  131 ,  231 ,  232 ,  332 . The magnetic films  150 ,  250 ,  350  include the magnetic thin films  151 ,  152 ,  251 ,  252 ,  351 ,  352  in which the frequency bands of the imaginary part μ″ of the complex permeability are set according to the control circuit, the high frequency circuit, and the power supply circuit. Thus, it is possible to suppress emission of the high frequency noises, which are generated in the control circuit (the semiconductor device  231 ) and the high frequency circuit (the semiconductor device  232 ) and emitted to the outside. Moreover, it is possible to suppress emission of the low frequency noises, which are generated in the power supply circuit (the semiconductor device  131 ) and emitted to the outside. Further, it is possible to suppress the electromagnetic noises intruding into the respective circuit sections from the outside. 
       (Modification) 
       [0084]    The above described embodiment may be modified in the following manner. 
         [0085]    As shown in  FIG. 7 , an electronic device  80  has semiconductor packages  100   a ,  200   a ,  300   a . A magnetic film  150   a  of the semiconductor package  100   a  includes the magnetic thin films  151 ,  152 , and an insulating film  153 . The insulating film  153  and the magnetic thin films  152 ,  151  are formed in this order from the surface of the wiring board  110 . Likewise, a magnetic film  250   a  of the semiconductor package  200   a  includes the magnetic thin films  251 ,  252 , and an insulating film  253 , and a magnetic film  350   a  of the semiconductor package  300   a  includes the magnetic thin films  351 ,  352 , and an insulating film  353 . By covering the wiring boards  110  to  310  and so on with the insulating films  150   a  to  350   a  in this manner, it is possible to eliminate restrictions due to properties of the magnetic thin films  151 ,  152  to  351 ,  352 , and to enhance the degree of freedom of manufacturing steps 
         [0086]    In  FIG. 7 , an insulating film having high adhesion may be formed between the magnetic thin film  152  and the magnetic thin film  151 . Likewise, an insulating film having high adhesion may be formed between the magnetic thin film  252  and the magnetic thin film  251 , and between the magnetic thin film  352  and the magnetic thin film  351 . 
         [0087]    The above described embodiments may be carried out in the following manners.
       In the respective embodiments, the number of the magnetic thin films included in the magnetic film may be appropriately changed to three or more.   In the respective embodiments, the number of the magnetic thin films included in the magnetic film on the first main face side (the upper face side in  FIG. 2 , for example) and the number of the magnetic thin films included in the magnetic film on the second main face side (the lower face side in  FIG. 2 , for example) may be different from each other. For example, in  FIG. 2 , the magnetic film on the upper face side may be either of the one including three or more magnetic thin films, the one including two magnetic thin films and one insulating film, and the one including two magnetic thin films and two insulating films.   In the respective embodiments, the order of stacking the magnetic thin films on the first main face side may be different from the order of stacking the magnetic thin films on the second main face side. For example, in the magnetic film  61   a  as shown in  FIG. 5 , the insulating film  62   a , the magnetic thin film  41   a , the insulating film  52   a , and the magnetic thin film  42   a  may be formed in this order from the surfaces of the wiring board  11  and the electronic components.   In the electronic device as shown in  FIG. 2 , end faces of the wiring board  11  may be covered with the magnetic film. In the same manner, in the electronic device  50  as shown in  FIG. 4 , and in the electronic device  60  as shown in  FIG. 5 , end faces of the wiring board  11  may be covered with the magnetic films.   In the electronic device  70  as shown in  FIG. 6 , resin may be filled between the semiconductor package  100  and the semiconductor package  200 . The resin serves to protect connection parts between the semiconductor package  100  and the semiconductor package  200  which are connected by the solder balls  71 . Moreover, the resin serves to enhance connecting strength between the semiconductor package  100  and the semiconductor package  200 . Also, the resin may be filled between the semiconductor package  200  and the semiconductor package  300 .   In  FIG. 1B , the electronic component  12   f , which serves as the antenna for wireless communication is not covered with the magnetic film  13 . The magnetic film  13  includes the magnetic thin films  41   a ,  42   a  having different properties from each other, in the same manner as the magnetic film  13   a  as shown in  FIG. 2 , for example.
 
Therefore, it is possible to cover the electronic component  12   f  with the magnetic thin film whose characteristics are set according to such frequency where the electronic component  12   f  does not receive or transmit signals. For example, in case of the antenna for conducting the wireless communication with the electromagnetic waves of several GHz, the magnetic thin film  42   a  whose characteristics are set according to the low frequency is formed so as to cover this antenna. In this case, the electromagnetic waves are shielded or attenuated by the magnetic thin film  42   a , and the influences of the electromagnetic waves are reduced. Thus, it is possible to reduce influences of noises.
       
 
         [0094]    As described above, the preferred embodiment and the modifications are described in detail. However, the present invention is not limited to the above-described embodiment and the modifications, and various modifications and replacements are applied to the above-described embodiment and the modifications without departing from the scope of claims.