Abstract:
An electric device for a vehicle includes: a circuit board having an attachment unit, which is attachable to a vehicular attachment unit, wherein an electric element for providing an electric circuit is mounted on the circuit board; and a shrinkage cover covering a surface of the electric element and a surface of the circuit board. The attachment unit of the circuit board is directly attachable to the vehicular attachment unit with a fastening element.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application is based on Japanese Patent Application No. 2013-97760 filed on May 7, 2013, the disclosure of which is incorporated herein by reference. 
       TECHNICAL FIELD 
       [0002]    The present disclosure relates to an electric device for a vehicle and a manufacturing method of the same. 
       BACKGROUND 
       [0003]    Conventionally, an electric device for a vehicle includes a circuit board, on which an electric element for providing an electric circuit is mounted, a casing for accommodating and supporting the circuit board, and a bracket for attaching the casing to an attachment unit of the vehicle. JP-A-2010-40992 teaches that the circuit board and the electric element are arranged in a forming mold, and the casing is formed together with the circuit board and the electric element integrally by a low-pressure transfer molding method with thermo-setting resin components. 
         [0004]    Here, in general, a conventional electric device includes a casing for accommodating a circuit board and a bracket for attaching the casing to an attachment unit of the vehicle. Accordingly, the number of elements in the electric device may easily increase, and a structure of the electric device may be complicated. Thus, it is required to simplify the structure of the device. 
       SUMMARY 
       [0005]    It is an object of the present disclosure to provide an electric device and a manufacturing method of the same. A structure of the electric device is simplified, and the number of elements in the electric device is reduced. 
         [0006]    According to a first aspect of the present disclosure, an electric device for a vehicle includes: a circuit board having an attachment unit, which is attachable to a vehicular attachment unit, wherein an electric element for providing an electric circuit is mounted on the circuit board; and a shrinkage cover covering a surface of the electric element and a surface of the circuit board. The attachment unit of the circuit board is directly attachable to the vehicular attachment unit with a fastening element. 
         [0007]    In the above electric device, the circuit board includes the attachment unit, which is attachable to the vehicle attachment unit. The attachment unit is attached to the vehicle attachment unit with the fastening element. Further, the circuit board and the electric element mounted on the circuit board are protected by the cover, which seals the surface thereof. Accordingly, it is not necessary to prepare a casing and a bracket in a conventional electric device. Thus, the structure of the electric device is simplified, and the number of elements in the electric device is reduced. 
         [0008]    According to a second aspect of the present disclosure, a manufacturing method of an electric device for a vehicle, which includes: a circuit board having an attachment unit attachable to a vehicular attachment unit, wherein an electric element for providing an electric circuit is mounted on the circuit board; and a cover covering a surface of the electric element and a surface of the circuit board, the manufacturing method includes: plating with metal on the attachment unit so that a metal thick film is formed, and mounting the electric element on the circuit board so that the circuit board is prepared; accommodating the circuit board, on which the electric element is mounted, in the cover made of resin or rubber and having a pouch shape; thermally press-bonding a periphery of the cover along an outer circumference of an opening of the cover to the circuit board; and shrinking the cover. 
         [0009]    In the above manufacturing method, the structure of the electric device is simplified, and the number of elements in the electric device is reduced. 
         [0010]    According to a third aspect of the present disclosure, a manufacturing method of an electric device for a vehicle, which includes: a circuit board having an attachment unit attachable to a vehicular attachment unit, wherein an electric element for providing an electric circuit is mounted on the circuit board; and a cover covering a surface of the electric element and a surface of the circuit board, the manufacturing method includes: sticking a sheet of the cover to a surface of the circuit board, on which the electric element is mounted; thermally press-bonding an outer periphery of the cover to the circuit board; shrinking the cover; and attaching a metal member for reinforcing the attachment unit in a through hole in the attachment unit of the circuit board from an outside of the cover. 
         [0011]    In the above manufacturing method, the structure of the electric device is simplified, and the number of elements in the electric device is reduced. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description made with reference to the accompanying drawings. In the drawings: 
           [0013]      FIG. 1  is a diagram showing a plan view of an electric device for a vehicle according to a first embodiment; 
           [0014]      FIG. 2  is a diagram showing a side view of the electric device for the vehicle according to the first embodiment; 
           [0015]      FIG. 3  is a diagram showing a bottom view of the electric device for the vehicle according to the first embodiment; 
           [0016]      FIG. 4  is a flowchart showing a manufacturing method of the electric device for the vehicle according to the first embodiment; 
           [0017]      FIG. 5A  is a diagram showing a circuit board formed at a circuit board forming step of the manufacturing method of the electric device for the vehicle according to the first embodiment, and  FIG. 5B  is a diagram showing a cross sectional view of the circuit board taken along line VB-VB in  FIG. 5A ; 
           [0018]      FIG. 6A  is a diagram showing a cover formed at a circuit board accommodation step of the manufacturing method of the electric device for the vehicle according to the first embodiment, and  FIG. 6B  is a diagram showing a cross sectional view of the cover taken along line VIB-VIB in  FIG. 6A ; 
           [0019]      FIG. 7  is a diagram showing a plan view of a work at circuit board forming step of the manufacturing method of the electric device for the vehicle according to the first embodiment; 
           [0020]      FIG. 8  is a diagram showing a side view of the work after the circuit board forming step of the manufacturing method of the electric device for the vehicle according to the first embodiment; 
           [0021]      FIG. 9  is a diagram showing the work at a cover press-bonding step of the manufacturing method of the electric device for the vehicle according to the first embodiment; 
           [0022]      FIG. 10  is a diagram showing a cross sectional view of the work taken along line X-X in  FIG. 9 ; 
           [0023]      FIG. 11  is a diagram showing a plan view of the work at a cover shrinking step of the manufacturing method of the electric device for the vehicle according to the first embodiment; 
           [0024]      FIG. 12  is a diagram showing a side view of the work at the cover shrinking step of the manufacturing method of the electric device for the vehicle according to the first embodiment; 
           [0025]      FIG. 13  is a diagram showing a bottom view of the work at the cover shrinking step of the manufacturing method of the electric device for the vehicle according to the first embodiment; 
           [0026]      FIG. 14  is a diagram showing a state of the electric device for the vehicle before attaching to an attachment unit of the vehicle, according to the first embodiment; 
           [0027]      FIG. 15  is a diagram showing a state of the electric device for the vehicle after attaching to the attachment unit of the vehicle, according to the first embodiment; 
           [0028]      FIG. 16  is a diagram showing a plan view of the work at a cover shrinking step of the manufacturing method of the electric device for the vehicle according to a first modification of the first embodiment; 
           [0029]      FIG. 17  is a diagram showing a side view of the work at the cover shrinking step of the manufacturing method of the electric device for the vehicle according to the first modification of the first embodiment; 
           [0030]      FIG. 18  is a diagram showing a bottom view of the work at the cover shrinking step of the manufacturing method of the electric device for the vehicle according to the first modification of the first embodiment; 
           [0031]      FIG. 19  is a diagram showing a plan view of an electric device for a vehicle according to a second embodiment; 
           [0032]      FIG. 20  is a diagram showing a bottom view of the electric device for the vehicle according to the second embodiment; 
           [0033]      FIG. 21  is a diagram showing a side view of the electric device for the vehicle according to the second embodiment; 
           [0034]      FIG. 22  is a flowchart showing a manufacturing method of the electric device for the vehicle according to the second embodiment; 
           [0035]      FIG. 23A  is a diagram showing a plan view of a circuit board formed by the manufacturing method of the electric device for the vehicle according to the second embodiment, and  FIG. 23B  is a diagram showing a cross sectional view of the circuit board taken along line XXIIIB-XXIIIB in  FIG. 23A ; 
           [0036]      FIG. 24  is a diagram showing a cover bonding step of the manufacturing method of the electric device for the vehicle according to the second embodiment; 
           [0037]      FIG. 25  is a diagram showing a plan view of the work after the cover bonding step of the manufacturing method of the electric device for the vehicle according to the second embodiment; 
           [0038]      FIG. 26  is a diagram showing a bottom view of the work after the cover bonding step of the manufacturing method of the electric device for the vehicle according to the second embodiment; 
           [0039]      FIG. 27  is a diagram showing a plan view of the work after the cover press-bonding step of the manufacturing method of the electric device for the vehicle according to the second embodiment; 
           [0040]      FIG. 28  is a diagram showing a front view of the work viewing from a connector side after the cover press-bonding step of the manufacturing method of the electric device for the vehicle according to the second embodiment; 
           [0041]      FIG. 29  is a diagram showing a plan view of the work at the cover shrinking step of the manufacturing method of the electric device for the vehicle according to the second embodiment; 
           [0042]      FIG. 30  is a diagram showing a front view of the work viewing from a connector side at the cover shrinking step of the manufacturing method of the electric device for the vehicle according to the second embodiment; 
           [0043]      FIG. 31  is a plan view of the work at a metallic member attaching step of the manufacturing method of the electric device for the vehicle according to the second embodiment; 
           [0044]      FIG. 32A  is a diagram showing a side view of the electric device for the vehicle at the metallic member attaching step of the manufacturing method according to the second embodiment before attaching the metallic member, and 
           [0045]      FIG. 32B  is a diagram showing the side view of the electric device for the vehicle after attaching the metallic member; 
           [0046]      FIG. 33A  is a diagram showing a side view of the electric device for the vehicle at the metallic member attaching step of the manufacturing method according to the second modification of the first embodiment before attaching the metallic member, and  FIG. 33B  is a diagram showing the side view of the electric device for the vehicle after attaching the metallic member; 
           [0047]      FIG. 34  is a diagram showing a front view of the work viewing from a connector side at the metallic member attaching step of the manufacturing method according to the third modification of the first embodiment; and 
           [0048]      FIG. 35  is a diagram showing a side view of the electric device at the metallic member attaching step of the manufacturing method according to the third modification of the first embodiment after the metallic member is attached. 
       
    
    
     DETAILED DESCRIPTION 
     First Embodiment 
       [0049]    An electric device for a vehicle according to the first embodiment is suitably used for an air bag ECU. As shown in  FIGS. 1 to 3 , the electric device includes a circuit board  10  and a cover  20 . 
         [0050]    The circuit board  10  is a substrate of the air bag ECU for detecting acceleration of the vehicle and for executing an inflation control process of the air bag based on a detection result. The circuit board  10  includes a printed board  11 , on which a printed wiring (not shown) is formed, an acceleration sensor  12  and a connector  13 , which are mounted on the printed board  11 , and an electric element Z. The printed board  11  is made of resin and has a plate shape with a rectangular shape. An attachment unit  14  as a device side attachment unit to be attached to an attachment unit  36  of the vehicle as a vehicle side attachment unit, as shown in  FIGS. 14 and 15 , is arranged on each side of the printed board  11  in a longitudinal direction. 
         [0051]    Each attachment unit  14  includes a through hole  15 , through which an attachment bolt  31  as a press-bonding member is inserted. The attachment unit  14  is reinforced with a metallic thick film  16 , which is formed by plating a metal around the through hole  15  on a front surface and a rear surface of the printed board  11 . the metallic thick film  16  is connected to the printed wiring. The thickness of the metallic thick film  16  is larger than the thickness of the printed wiring. 
         [0052]    The electric circuit of the circuit board  10  includes the printed wiring made of predetermined metallic material on the printed board  11  and various electric elements arranged on the printed board  11  such as an acceleration sensor  12 , a connector  13  and other electric elements Z. The acceleration sensor  12  is a G sensor for detecting acceleration of the vehicle as one of physical quantities of behavior of the vehicle. The connector  13  is connected to the electric circuit and disposed on the circuit board  10 . The connector  13  is connected to a vehicular wiring such as a vehicular harness. 
         [0053]    The cover  20  is made of resin and has a pouched shape. The cover  20  accommodates the circuit board  10  and various electric elements  12 ,  13 , Z, which are arranged on the circuit board  10 , therein. After a portion around an opening of the cover  20  is thermally press-bonded, an inside of the cover  20  is evacuated so that the cover  20  is shrunk. Thus, the circuit board  10  and the electric element  12 ,  13 , Z protected by the cover  20  are prevented from damage and have a water proof property. Here, the resin of the cover  20  is, for example, polyolefin resin, fluorine resin, silicone resin or the like. 
         [0054]    Next, a manufacturing method of the electric device for the vehicle according to the present embodiment will be explained with reference to  FIGS. 4 to 13 . As shown in  FIG. 4 , the device is manufactured by executing a circuit board forming step S 11 , a circuit board accommodating step S 12 , a cover press-bonding step S 13  and a cover shrinking step S 14  in this order. 
         [0055]    At the circuit board forming step S 11 , as shown in  FIGS. 5A and 5B , at a step for forming the printed board  11 , the attachment unit  14  having the through holes  15  on both sides in the longitudinal direction of the unit  14  is formed. Further, the metallic thick film  16  is formed by plating with metal around the through holes  15  of the attachment unit  14 . After that, various electric elements such as the acceleration sensor  12  and the connector  13  are mounted on the printed board  11  at predetermined positions, respectively, so that the circuit board  10  is formed. 
         [0056]    At the circuit board accommodating step S 12 , as shown in  FIGS. 6A and 6B , the cover  20  having a pouched shape and made of resin is prepared. The cover  20  has the dimensions capable of accommodating the circuit board  10 . The cover  20  includes the opening  21  on one end, i.e., a left side in  FIG. 6A . Further, another opening  22  having a rectangular shape is formed on each side in the longitudinal direction (i.e., the up-down direction in  FIG. 6A ) of the cover  20 , which corresponds to the attachment unit  14  of the circuit board  10 . 
         [0057]    As shown in  FIG. 7 , the circuit board  10  formed at the circuit board forming step S 11  is inserted into the cover through the opening  21  so that the board  10  is accommodated in the cover  20 . Thus, as shown in  FIG. 8 , the circuit board  10  is accommodated in the cover  20  under a condition that the attachment unit  14  and the openings  22  are aligned. 
         [0058]    At the cover press-bonding step S 13 , as shown in  FIGS. 9 and 10 , a periphery portion along an outer circumference of each opening  22  of the cover  20  is thermally clamped (press-bonded) to the outer periphery of the attachment unit  14 . Further, the periphery portion of the opening  21  of the cover  20  is also thermally press-bonded to the circuit board  10 . Thus, three openings  21 ,  22  other than a part of the opening  21  of the cover  20  are sealed. 
         [0059]    At the cover shrinking step S 14 , with using a vacuum pump (not shown), the inside of the cover  20  is evacuated through the opening  21 . Thus, as shown in  FIGS. 11 to 13 , the cover  20  is shrunk in whole. Thus, in the present embodiment, a packaging process is executed using the cover  20  as a vacuum seal. Thus, the cover  20  adheres tightly to the surface of various electric elements  12 ,  13 , Z and the surface of the circuit board  10  so that the cover  20  seals the various electric elements  12 ,  13 , Z and the circuit board  10 . Then, if necessary, a finishing process is executed, so that the electric device for the vehicle is completed, as shown in  FIGS. 1 to 3 . 
         [0060]    As shown in  FIGS. 14 and 15 , the electric device for the vehicle according to the present embodiment is attached to the attachment unit  36  of the vehicle, which is arranged on a vehicle frame  35  made of metal, with an attachment bolt  31  and a nut  32  as a fastening member. Specifically, the electric device is arranged under a condition that a pair of attachment holes  37 , which are arranged at two points of the attachment unit  36 , and two through holes  15  arranged at two points of the circuit board  10  are aligned to each other, respectively. 
         [0061]    A shaft of the attachment bolt  31  is inserted into the through hole  15  and the attachment hole  37 . Then, a top end of the shaft of the attachment bolt  31 , which protrudes from the attachment hole  37 , is fastened with the nut  32  so that the electric device is attached to the vehicle. Thus, the attachment unit  14  of the circuit board  10  is directly attached to the attachment unit  36  of the vehicle. Here, the top of the attachment bolt  31  contacts the metallic thick film  16 , which is arranged on the surface of the attachment unit  14 . The nut  32  fastened to the top end of the attachment bolt  31  electrically connects with the vehicle frame  35  via a washer  33 . Thus, the electric circuit as a printed wiring of the circuit board  10  electrically connects with the vehicle frame  35  via the metallic thick film  16 , the attachment bolt  31 , the nut  32  and the washer  33 , so that the electric circuit connects to ground, i.e., a body of the vehicle. 
         [0062]    In the electric device for the vehicle according to the present embodiment, the circuit board  10  includes the attachment unit  14  to be attached to the attachment unit  36  of the vehicle. The attachment unit  14  is directly attached to the attachment unit  36  of the vehicle with the bolt  31  and the nut  32 . The circuit board  10  and the electric elements mounted on the circuit board  10  are protected by the cover  20 , which seals the surface of the circuit board  10  and the electric elements. Accordingly, it is not necessary to prepare a casing and a bracket in a conventional electric device. Accordingly, the structure of the electric device is simplified, and the number of elements of the electric device is much reduced. 
         [0063]    The attachment  14  of the electric device includes the through hole  15 , through which the bolt  31  is inserted. The through hole  15  is reinforced with the metallic thick film  16 , which is arranged around the hole  15 . Thus, the attachment unit  14  of the circuit board  20  is fixed to the attachment unit  36  of the vehicle surely and strongly. 
         [0064]    In the present embodiment, the fastening member is provided by the attachment bolt  31 , which is to be inserted into the through hole  15  of the attachment unit  14  and the attachment hole  37  of the attachment unit  36  of the vehicle, and the nut  32  to be attached to the bolt  31 . Thus, the electric circuit (i.e., the printed wiring) of the circuit board  10  and the vehicle frame  35  are connected to each other via the metallic thick film  16 , the attachment bolt  31  and the nut  32 . Thus, it is not necessary to prepare an additional wiring for grounding to the body of the vehicle. The number of elements in the electric device is reduced, and the manufacturing cost of the electric device is also reduced. Further, the fastening manner of the bolt  31  and the nut  32  provides large fastening force and strong fixation. Thus, the behavior of the vehicle is transmitted to the circuit board  10  with high accuracy. Furthermore, the bolt  31  and the nut  32  are general purpose elements, and therefore, the manufacturing cost is reduced. 
         [0065]    In the present embodiment, the cover  20  is made of resin and has a sac-like shape or a pouch shape. Accordingly, the circuit board  10  and various electric elements  12 ,  13 , Z accommodated in the cover  20  are easily sealed. Thus, the circuit board  10  and various electric elements  12 ,  13 , Z accommodated in the cover  20  are protected from water, so that the electric device has high water protection. Further, the damage of the electric device is prevented. 
         [0066]    The manufacturing method of the electric device for the vehicle according to the present embodiment provides the electric device having the simple structure and the small number of elements, which is easily and simply manufactured. 
         [0067]    (First Modification) 
         [0068]    A first modification of the above embodiment will be explained with reference to  FIGS. 16 to 18 . In the above embodiment, at the cover shrinking step S 14  in the manufacturing method of the electric device for the vehicle, the packaging process with using the vacuum sealing method is performed. Alternatively, in the first modification, the packaging process may be performed with using heat shrinkage of a cover  120 . 
         [0069]    In the first modification, the cover  120  is made of rubber and has a sac-like shape having a predetermined thickness. The cover  120  has the sac-like shape with three openings  121 ,  122 , which is similar to the cover  20  according to the first embodiment. The cover  120  is made of rubber having a contractile property (i.e., a shrinkage property), which is different from the cover  20 , and has the thickness larger than the cover  20 . 
         [0070]    The cover shrinking step S 14  according to the first modification is performed after the circuit board forming step S 11 , the circuit board accommodating step S 12 , and the cover press-bonding step S 13 , similar to the first embodiment. Thus, after the cover press-bonding step S 13 , the periphery of the cover  120  around the opening  121 ,  122  is thermally adhered to the circuit board  10  so that three openings  121 ,  122  of the cover  120  are sealed. 
         [0071]    Under the above situation, when the cover shrinking step S 14  in the first modification starts, the cover  120  made of rubber material and having a pouch shape is shrunk as a whole by the heating process, as shown in  FIGS. 16-18 . At this time, since the cover  120  is made of rubber material, and has a thickness larger than the cover  20  according to the first embodiment, a clearance between the cover  120  and the surface of various electric elements  12 ,  13 , Z and the circuit board  10  is formed, which is different from the first embodiment. Specifically, the cover  120  covers the surface of various electric elements  12 ,  13 , Z and the circuit board  10 , so that the cover  120  has a flat surface, which does not fit the convexity and concavity on the surface of the various electric elements  12 ,  13 , Z and the circuit board  10 . 
         [0072]    Thus, in the first modification, the cover  120  is made of rubber material having a heat-shrinkable property and has a pouch shape. Further, the cover  120  has a thickness larger than the cover  20  made of resin according to the first embodiment. Accordingly, the shrinkage rate of the cover  120  is easily controlled so as not to adhere to the various electric elements  12 ,  13 , Z. Thus, the clearance between the cover  120  and the surface of various electric elements  12 ,  13 , Z and the circuit board  10  is surely and easily secured. Thus, the cover  120  maintains a flat shape, so that a part of the surface of the cover  120 , on which a label is attached, is easily secured. Further, since there is no convexity and concavity, a damage caused by a scratch is prevented. 
         [0073]    The rubber material of the cover  120  having the heat shrinkage property is, for example, silicon rubber, fluoride silicon rubber, or neoprene rubber. The thickness of the cover  20  is determined according to the heat shrinkage rate of the rubber material. 
       Second Embodiment 
       [0074]    An electric device for a vehicle according to a second embodiment will be explained with reference to  FIGS. 19 to 32 . The electric device according to the second embodiment includes the circuit board  10  and the cover  220 , as shown in  FIGS. 19 to 21 . The electric device according to the second embodiment is similar to the first embodiment except for a metal plate  17  as a metal member with a hook. Further, the cover  220  is different from the cover  20  according to the first embodiment. 
         [0075]    The circuit board  10  according to the second embodiment includes the printed board  11 , the acceleration sensor  12  and the connector  13 , which are mounted on the printed board  11 , and other electric elements Z, similar to the circuit board  10  according to the first embodiment. Here, the through hole  15  is formed on both sides in the attachment unit  14  along the longitudinal direction of the printed board  11 . The metal plate  17  having the hook as a metal member for reinforcing the attachment unit  14  is inserted in the through hole  15 . 
         [0076]    The metal plate  17  includes a base unit  17   a  having a rectangular shape with a through hole  17   b  at a center of the base unit  17 , and four hooks  17   c  extending from a periphery around the through hole  17   b  in an axial direction. The metal plat  17  is attached to each attachment unit  14  such that four hooks  17   c  are inserted in the attachment unit  14  from one side thereof such as an upper side or a front surface in  FIG. 21 . Then, four tops of the hooks  17   c  protruded from the other side opposite to the one side such as a lower side or a back surface are bent to the outside in the radial direction, so that the metal plate  17  is attached to the attachment unit  14 . 
         [0077]    The cover  220  according to the second embodiment includes two sheets made of resin and having a rectangular sheet shape. The resin material of the cover  220  may be the same as the cover  20  according to the first embodiment. Each sheet of the cover  220  is bonded to a respective surface of the printed board  11 . The outer periphery of the cover  220  bonded to both of the front surface and the back surface of the printed board  11  is thermally press-bonded to the outer periphery of the printed board  11 . Then, similar to the first embodiment, the inside of the cover  220  is vacuumed so that the cover  220  is shrunk. Thus, the electric elements  12 ,  13 , Z and the circuit board  10  covered with the cover  220  are protected from damage and have a water proof property. 
         [0078]    Next, a manufacturing method of the electric device for the vehicle according to the second embodiment will be explained with reference to  FIGS. 22 to 32 . The electric device according to the present embodiment is manufactured by executing the cover sticking step S 21 , the cover press-bonding step S 22 , the cover shrinking step S 23 , and the metal member mounting step S 24  in this order. 
         [0079]    At the cover sticking step S 21 , as shown in  FIGS. 23A and 23B , in a manufacturing process of the printed board  11 , the printed board  11  is prepared such that the attachment unit  14  having the through hole  15  on both sides in the longitudinal direction thereof is formed in the printed board  11 . The electric elements  12 ,  13 , Z are mounted on the printed board  11  at certain positions, respectively. After that, as shown in  FIGS. 24 to 26 , the cover  220  made of resin and having a rectangular sheet shape is stuck to each side of the circuit board  10 , on which the electric elements  12 ,  13 , Z are mounted. 
         [0080]    At the cover press-bonding step S 22 , the outer periphery of each sheet of the cover  220  is thermally press-bonded to the outer periphery of the circuit board  10 . Specifically, as shown in  FIGS. 27 and 28 , the outer periphery of the cover  220  stuck to the front surface of the printed board  11  and the periphery of the cover  220  around the through hole  15  are thermally press-bonded to the outer periphery of the printed board  11  and the periphery of the board  11  around the through hole  15 . Further, as shown in  FIG. 28 , the outer periphery  220   a  of the cover  220  stuck to the back surface of the printed board  11  and the periphery of the cover  220  around the through hole  15  are thermally press-bonded to the outer periphery of the printed board  11  and the periphery of the board  11  around the through hole  15 . Thus, the outer periphery  220   a  of the cover  220  and the periphery of the cover  220  around the through hole  15  are sealed except for a part of the cover  220 . 
         [0081]    At the cover shrinking step S 23 , the inside of the cover  220  is vacuumed from the opening  221  with a vacuum pump (not shown), for example. As shown in  FIGS. 29 and 30 , the cover  220  is shrunk as a whole. Specifically, similar to the first embodiment, the package processing with using the vacuum package of the cover  220  is utilized in the second embodiment. Thus, the cover  220  is adhered to the surface of the electric elements  12 ,  13 , Z and the circuit board  10  so that the cover  220  seals the electric elements  12 ,  13 , Z and the circuit board  10 . 
         [0082]    At the metal member mounting step S 24 , as shown in  FIGS. 31 ,  32 A and  32 B, the metal plate  17  having the hook as a metal member for reinforcing is mounted in the through hole  15  from an outside of the cover  220 . The through hole  15  is formed in the attachment unit  14  of the circuit board  10 . In this case, the metal plate  17  having the hook is mounted in the attachment unit  14  such that four hooks  17   c  are inserted into the through hole  15  from one side of the attachment unit  14  (i.e., the upper surface or the front surface in  FIG. 32 ), and tops of the hooks  17   c  protruded from the other side of the unit  14  (i.e., the lower surface or the back surface in  FIG. 32 ) are bent to the outside in the radial direction. Here, although each through hole  15  is covered with the cover  220 , the cover  220  easily breaks when the hooks  17   c  is inserted into the through hole  15 . Therefore, the metal plate  17  with the hooks is easily attached to the unit  14 . After that, if necessary, a finishing process is performed, so that the electric device for the vehicle shown in  FIGS. 19 to 21  is completed. 
         [0083]    Thus, the electric device for the vehicle according to the present embodiment is mounted to the attachment unit  36  of the vehicle, which is arranged on the vehicle frame  35  made of metal, via a fastening member such as the bolt  31  and the nut  32 , similar to the first embodiment, as shown in  FIGS. 14 and 15 . 
         [0084]    Thus, in the electric device for the vehicle according to the second embodiment, the circuit board  10  includes the attachment unit  14  to be attached to the attachment unit  36  of the vehicle. The attachment unit  14  is directly attached to the attachment unit  36  with the bolt  31  and the nut  32 . Accordingly, the structure of the electric device is simplified, and the number of elements in the electric device is reduced, which are similar to the first embodiment. 
         [0085]    The cover  220  according to the second embodiment is made of resin material, and has the rectangular sheet shape. Alternatively, the cover  220  may be made of rubber material having the heat shrinkage property and have the rectangular sheet shape. Further, the cover  220  may be thermally shrunk instead of the vacuum shrinkage process. In this case, the thickness of the cover  220  may be enlarged, so that the effects similar to the first embodiment are obtained. 
         [0086]    (Second Modification) 
         [0087]    A second modification will be explained with reference to  FIGS. 33A and 33B . In the second embodiment, the metal plate  17  having the hook reinforces the attachment unit  14 . Alternatively, as shown in  FIGS. 33A and 33B , a pair of engagement elements  18 A,  18 B may be used as the metal member. 
         [0088]    In the above case, one engagement element  18 A includes a base unit  181 A having a rectangular shape with a through hole at a center thereof, and a large diameter ring unit  182 A, which is protruded from a periphery around the through hole on one side of the base unit  181 A. The large diameter ring unit  182 A includes a through hole, which has a circular cross sectional shape, arranged inside of the unit  182 A. The other engagement element  18 B includes a base unit  181 B having a rectangular shape with a through hole at a center thereof, and a small diameter ring unit  182 B, which is protruded from a periphery around the through hole on one side of the base unit  181 B. The small diameter ring unit  182 B is engaged with the inside of the large diameter ring unit  182 A. 
         [0089]    A pair of the engagement units  18 A,  18 B is attached to each attachment unit  14  of the printed board  11 , as shown in  FIGS. 33A and 33B . First, the large diameter ring unit  182 A of one engagement element  18 A is engaged in the through hole  15  from the front side (i.e., the upper surface in  FIG. 33A ) of the attachment unit  14  in the printed board  11 . Then, the small diameter ring unit  182 B of the other engagement element  18 B is engaged in the inside of the large diameter ring unit  182 A, which is disposed in the through hole  15 , from the back side (i.e., the lower surface in  FIG. 33A ) of the attachment unit  14  in the printed board  11 . Thus, the base unit  181 A of the engagement unit  18 A contacts the front surface of the attachment unit  14 , and the base unit  181 B of the engagement unit  18 B contacts the back surface of the attachment unit  14 . Thus, a pair of the engagement units  18 A,  18 B reinforces the attachment unit  14 . 
         [0090]    (Third Modification) 
         [0091]    A third modification will be explained with reference to  FIGS. 34 and 35 . In the third modification, a metal element  19  shown in  FIGS. 34 and 35  may be used instead of the pair of engagement units  18 A,  18 B according to the second modification. The metal element  19  includes a first engagement unit  19 A, which is similar to the one engagement unit  18 A according to the second modification, a second engagement unit  19 B, which is similar to the other engagement unit  18 B according to the second modification, and a connector  19 C for connecting the first engagement unit  19 A and the second engagement unit  19 B. Thus, the first engagement unit  19 A includes a base unit  191 A and a large diameter ring unit  192 A. The second engagement unit  19 B includes a base unit  191 BA and a small diameter ring unit  192 B. 
         [0092]    The metal element  19  is attached to each attachment unit  14  of the printed board  11 , similar to the second modification. As shown in  FIG. 35 , first, the large diameter ring unit  192 A of the first engagement element  19 A is engaged in the through hole  15  from the front side (i.e., the upper surface in  FIG. 35 ) of the attachment unit  14  in the printed board  11 . Then, the small diameter ring unit  192 B of the second engagement element  19 B is engaged in the inside of the large diameter ring unit  192 A, which is disposed in the through hole  15 , from the back side (i.e., the lower surface in  FIG. 35 ) of the attachment unit  14  in the printed board  11 . Thus, the metal element  19  reinforces the attachment unit  14 , similar to the second modification. 
         [0093]    In the metal element  19  according to the third modification, the first engagement unit  19 A and the second engagement unit  19 B are connected by the connector  19 C so that they are integrated with each other. Thus, the handling of the metal element  19  is easy, so that the attachment operation of the metal element  19  to the unit  14  is easily performed. 
         [0094]    While the present disclosure has been described with reference to embodiments thereof, it is to be understood that the disclosure is not limited to the embodiments and constructions. The present disclosure is intended to cover various modification and equivalent arrangements. In addition, while the various combinations and configurations, other combinations and configurations, including more, less or only a single element, are also within the spirit and scope of the present disclosure.