Abstract:
Provided is a bending rigid printed wiring board which facilitate the mounting of electric parts (realization of a high producibility and high assemblability substrate circuit) and enables spaces to be saved and which can be easily manufactured. 
     That is, provided is a bending rigid printed wiring board, which is characterized in that a heat resistant resin layer is laminated on a front surface of a hard core material provided so as to contain a gap portion and also on a top surface of the gap portion, in that a heat resistant resin layer is laminated on a rear surface of the core material except the gap portion, in that a conductor layer is laminated and firmly fixed via the heat resistant resin layers and in that the conductor layer is etched, whereby a circuit is formed.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a printed wiring board which permits easy mounting of electrical parts and the like and which not only enables spaces to be saved, but also facilitates manufacturing. 
     Electrical components tend to increase in number from the requirements for an improvement in the functions of products of, for example, automobiles. For this reason, in order to use limited spaces efficiently, it is required that electrical parts and the like be easily mounted and that spaces necessary for their mounting be reduced. 
     Therefore, in performing the wiring and branching of electric wires for automobiles and the like, there has been used an electric connection box which is constructed so that parts, such as connections to wire harness, fuses and relays, are collected in one place and connected there. And as the above-described electric connection box, there has been known an electric connection box in which a rigid printed wiring board that is constructed in such a manner that a circuit is formed on the surface of a hard base material is used as a wiring material for distributing power from a power source (hereinafter referred to as an internal circuit). 
     A method of manufacturing a rigid printed wiring board  100  by prior art will be described with reference to  FIGS. 15(   a ) to  15 ( c ). 
     According to the prior art, a laminate  103  which is obtained by laminating a conductor layer  102 , such as copper foil and silver foil, each on a front surface and a rear surface of a hard base material  101  made of an insulating material, is used (refer to  FIG. 15(   a )), and through holes  104  (a via through hole  104   a  which ensures electrically conducting properties for the conductor layers  102  on the front and rear surfaces and a mounting through hole  104   b  for providing a connection terminal  20 ) are formed by planting a substrate through-hole provided by drilling the laminate  103 . At the same time, by etching the above-described laminate  103 , a circuit  102   a  is formed on the front and rear surfaces of the hard base material  101  (refer to  FIG. 15(   b )), and the front surface of the circuit is coated with a resist (an insulating material)  105 , whereby a rigid printed wiring board  100  is manufactured (refer to  FIG. 15(   c )). Also, a multilayer wiring board has been similarly manufactured by performing laminating and pressing. 
     In a case where by use of the prior art, an electrical part is mounted on the rigid printed wiring board  100  and a wiring material (a substrate circuit) of an internal circuit as used in electrical equipment is formed, as shown in  FIGS. 16(   a ) to  16 ( c ), the mounting through hole  104   b  for the insertion of the connection terminal  20  is provided beforehand in a connector for the connection to the electrical part and a connection to the electrical part, such as a fuse and a relay. After the press fitting of the connection terminal  20  into the above-described mounting through hole  104   b , the rigid printed wiring board  100  and the connection terminal  20  are connected together after going through the step of flow soldering or reflow soldering. 
     As shown in  FIG. 16(   a ), in connecting the connection terminal  20  to the rigid printed wiring board  100  which is provided with the via through hole  104   a  for ensuring the conducting properties of the circuits formed on the front and rear surfaces of the substrate and the mounting through hole  104   b  into which the connection terminal  20  is press fitted, because the above-described mounting through hole  104   b  is formed from a hole which pierces through the substrate, in a case where a substrate circuit in which the connection terminals  20  are provided at prescribed positions each on the front surface and rear surface of the substrate, it is necessary to design a substrate circuit in such a manner that the positions of the connection terminals  20  do not overlap on the front and rear surfaces. Therefore, the prior part had the disadvantage that the projected area of the substrate circuit becomes large. 
     In forming a substrate circuit in which the connection terminals  20  are provided at prescribed positions each on the front surface and rear surface of the substrate, it was necessary to solder the connection terminals  20  by performing the step of fixing the connection terminals  20  provided at prescribed positions on the front surface of the rigid printed wiring board  100  by solders  21  as shown in  FIG. 16(   b ), and the step of fixing the connection terminals  20  provided at prescribed positions on the rear surface of the rigid printed wiring board  100  by solders  21  as shown in  FIG. 16(   c ). That is, it has been necessary to perform the soldering step twice. 
     Therefore, as shown in  FIGS. 17(   a ) and  17 ( b ), there have been proposed techniques which involve connecting two rigid printed wiring boards  100 , in each of which a connection terminal  20  is provided at a prescribed position on a front surface, by means of an electric wire  107 , and bending the two rigid printed wiring boards  100  in an electric wire portion, whereby a substrate circuit in which the connection terminals  20  are provided at prescribed positions on both surfaces is obtained (refer to Patent Document 1, for example).
     [Patent Document 1] Japanese Patent Application No. 2004-192546   

     SUMMARY OF THE INVENTION 
     In a substrate circuit which is formed in such a manner that two rigid printed wiring boards  100  connected together by an electric wire  107  are bent in the above-described electric wire portion, connection terminals  20  which are provided at prescribed positions on each of the front surfaces of the two rigid printed wiring boards  100  connected together by the electric wire  107  are soldered and fixed (refer to  FIG. 17(   a )), and after that, the two rigid printed wiring boards  100  are bent in the above-described electric wire portion, whereby a substrate circuit in which the connection terminals are provided at prescribed positions on both surfaces is obtained (refer to  FIG. 17(   b )). Therefore, it is necessary only that the soldering step for fixing the connection terminals  20  be performed once and besides the connection terminals  20  can be provided at arbitrary positions on both surfaces of the substrate. 
     However, it is necessary to install the electric wire  107  in such a manner that the circuits of the two rigid printed wiring boards  100  are connected together, and it takes time to perform this wire installation step. At the same time, the larger the number of the electric wires  107  for connecting the circuits of the substrates, the more difficult to bend the two rigid printed wiring boards in the electric wire portion will be. Besides the prior art has had the disadvantage that the space occupied by the electric wire  107  after the bending becomes large. Furthermore, because it is difficult to completely make equal the length of each of the electric wires  017  which connect the circuits of the two rigid printed wiring boards  100 , it has been difficult to uniformly control the shape after the bending. 
     In the present invention, therefore, in a rigid printed wiring board which is formed in such a manner that an arbitrary circuit is formed on a front surface of a hard base material by etching a laminate, a bent portion obtained by partially reducing the thickness of the base material is provided so that the rigid printed wiring board can be bent in this bent portion. 
     Also, a circuit for large current (for example, an inner circuit of an electric connection box) and a circuit for small current (for example, an electronic circuit) are formed in a bending rigid printed wiring board, whereby the substrate performance can be improved. 
     In a bending rigid printed wiring board of the present invention, a heat resistant resin layer is laminated on a front surface of a hard core material provided so as to contain a gap portion and also on a top surface of the gap portion, a heat resistant resin layer is laminated on a rear surface of the core material except the gap portion, a conductor layer is laminated and firmly fixed via the heat resistant resin layers, and the conductor layer is etched, whereby a circuit is formed. 
     Conductor portions having different layer thicknesses are formed on the same surface of the conductor, whereby a circuit for large current and a circuit for small current are formed on the same substrate. 
     A method of manufacturing a bending rigid printed wiring board of the present invention comprises a step of burying a heat resistant resin material in a gap portion provided in a hard core material, a step of forming a laminate by laminating a conductor layer each on a front surface and a rear surface of the hard core material via heat resistant resin layers and performing hot pressing, a step of forming a circuit on the front surface and rear surface of the hard base material by etching the laminate and of removing the conductor layer on the rear surface of the gap portion of the hard core material, and a step of removing the heat resistant resin material buried in the gap portion along with the heat resistant resin material on the rear surface of the heat resistant resin material, whereby a bent portion obtained by partially reducing the thickness of the hard base material is formed. A rigid printed wiring board capable of being bent in the bent portion is obtained by performing the steps. 
     According to a bending rigid printed wiring board of the present invention, by providing a bent portion obtained by partially reducing the thickness of the hard base material, it is possible to bend the printed wiring board in the bent portion. 
     In a case where an electrical part is mounted on the bending rigid printed wiring board of the present invention and a wiring material (a substrate circuit) of an internal circuit as used in electrical equipment is formed, after the provision of connection terminals at prescribed positions on a front surface of the rigid printed wiring board, the rigid printed wiring board is bent in the above-described bent portion, whereby it is possible to obtain a substrate circuit in which the connection terminals are provided on both surfaces. Therefore, the installation positions of the connection terminals can be arbitrarily designed and the soldering step of the connection terminals is performed only once. Furthermore, unlike a substrate circuit in which two rigid printed wiring boards connected together by an electric wire are bent in the electric wire portion, one rigid printed wiring board is bent in a bent portion obtained by partially reducing the thickness of a hard base material and, therefore, it is unnecessary to install electric wires for connecting together the circuits of opposed substrate surfaces. 
     Furthermore, in the bending rigid printed wiring board of the present invention, a gap portion is formed beforehand in part of the hard core material and a heat resistant resin material is buried in this gap portion. And at the same time, a laminate which is obtained by laminating a conductor layer on the front surface and rear surface of the hard core material via a heat resistant resin layer is used, and a heat resistant resin material buried in the gap portion is removed from the above-described laminate, whereby it is possible to easily form a bent portion which is obtained by partially reducing the thickness of the hard base material. Unlike a rigid-flexible substrate of multilayer structure which is constituted by multiple layers of a polyimide film and the like, which have different properties, and combines a flexible portion and a rigid portion, the bending rigid printed wiring board is simple in construction and can be manufactured at low cost. 
     Moreover, in manufacturing the bending rigid printed wiring board, conductor portions having different layer thicknesses are formed on the same surface of the conductor layer and a circuit for large current (for example, an inner circuit of an electric connection box) and a circuit for small current (for example, an electronic circuit) are formed, whereby it is possible to improve the substrate performance. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1(   a ) to  1 ( d ) are sectional views which explain a method of manufacturing a laminate; 
         FIGS. 2(   a ) to  2 ( c ) are plan views which show a heat resistant resin material buried in a gap portion; 
         FIGS. 3(   a ) to  3 ( d ) are sectional views which explain a method of manufacturing a bending rigid printed wiring board according to the present invention; 
         FIGS. 4(   a ) to  4 ( d ) are sectional views which explain a method of manufacturing a bending rigid printed wiring board in another embodiment; 
         FIGS. 5(   a ) to  5 ( c ) are sectional views which explain a method of manufacturing a bending rigid printed wiring board (a single-side wiring board); 
         FIGS. 6(   a ) to  6 ( e ) are sectional views which explain a method of manufacturing a bending rigid printed wiring board (a multilayer wiring board); 
         FIGS. 7(   a ) to  7 ( d ) are partial sectional views which explain a method of manufacturing a bending rigid printed wiring board provided with conductor portions having different layer thicknesses on the same surface; 
         FIGS. 8(   a ) to  8 ( c ) are first explanatory diagrams of a method of manufacturing a bending rigid printed wiring board in which a circuit for large current and a circuit for small current are formed on the same surface; 
         FIGS. 9(   a ) and  9 ( b ) are second explanatory diagrams of a method of manufacturing a bending rigid printed wiring board in which a circuit for large current and a circuit for small current are formed on the same surface; 
         FIGS. 10(   a ) and  10 ( b ) are third explanatory diagrams of a method of manufacturing a bending rigid printed wiring board in which a circuit for large current and a circuit for small current are formed on the same surface; 
         FIGS. 11(   a ) to  11 ( d ) are fourth explanatory diagrams of a method of manufacturing a bending rigid printed wiring board in which a circuit for large current and a circuit for small current are formed on the same surface; 
         FIGS. 12(   a ) and  12 ( b ) are fifth explanatory diagrams of a method of manufacturing a bending rigid printed wiring board in which a circuit for large current and a circuit for small current are formed on the same surface; 
         FIGS. 13(   a ) to  13 ( d ) are sectional views which explain a method of manufacturing a substrate circuit in which connection terminals are provided at prescribed positions in a bending rigid printed wiring board; 
         FIGS. 14(   a ) and  14 ( b ) are sectional views of a substrate circuit in which connection terminals are provided at prescribed positions; 
         FIGS. 15(   a ) to  15 ( c ) are sectional views which explain a method of manufacturing a rigid printed wiring board by prior art; 
         FIGS. 16(   a ) to  16 ( c ) are sectional views of a substrate circuit in which connection terminals are provided at prescribed positions in a rigid printed wiring board by prior art; and 
         FIGS. 17(   a ) and  17 ( b ) are diagrams which show other examples of the method shown in  FIGS. 15(   a ) to  15 ( c ). 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A bending rigid printed wiring board and a method of manufacturing the bending rigid printed wiring board in embodiments of the present invention will be described with reference to  FIG. 1  to  FIGS. 15(   a ) to  15 ( c ). 
     The bending rigid printed wiring board  10  of this embodiment is such that in a bending rigid printed wiring board  10  in which an arbitrary circuit  14  is formed by etching a laminate  6  which is obtained by laminating a conductor layer  4  each on the front surface and rear surface of a hard base material  5 , a bent portion  10 A which is obtained by partially reducing the thickness of the above-described hard base material  5  is formed. 
     In this embodiment, as shown in  FIGS. 1(   a ) to  1 ( d ) (sectional views) which illustrate the manufacturing process of a laminate, a hard core material  1  from which a portion corresponding to the bent portion has been removed is used and a heat resistant resin material  2  is buried in a relevant gap portion (the portion from which the hard core material has been removed)  1 A. And a conductor layer  4  is laminated each on the front surface and rear surface of the hard core material  1 , in which the heat resistant resin material  2  is buried in the gap portion  1 A, via heat resistant resin layers  31 ,  32 , and after that, hot pressing is performed, whereby the laminate  6  in which the conductor layer  4  is laminated each on both surfaces of the hard base material  5  is fabricated. 
     In the embodiment shown in  FIGS. 1(   a ) to  1 ( d ), a hard core material  1  formed from a glass epoxy resin is used. In the center part of the flat-pate-like hard core material  1  having a layer thickness of 0.4 mm, there is provided a gap portion  1 A which is obtained by removing part of the core material in groove form, whereby the gap portion  1 A was formed in a place corresponding to the bent portion (refer to  FIG. 1(   a )). 
     And a heat resistant resin material  2 , such as a Teflon (registered trademark) sheet having a film thickness of 0.4 mm and silicone rubber, is buried in the above-described gap portion  1 A, whereby the hard core material  1  in which the heat resistant resin material  2  is buried at a position corresponding to the bent portion is fabricated (refer to  FIG. 1(   b )). 
     By forming the gap portion  1 A beforehand in part of the hard core material, it is possible to easily reduce part of the thickness of the hard base material by removing, in a succeeding step, the heat resistant resin material  2  buried in this gap portion  1 A. 
     Also, by burying the heat resistant resin material  2  in the gap portion  1 A of the hard core material  1 , it is possible to make the pressure during hot pressing uniform in a succeeding step (during the fabrication of the laminate  6  by laminating the conductor layer  4 ). 
     After the burying of the heat resistant resin material  2  in the gap portion  1 A, a copper layer  4  having a film thickness of 200 μm to 600 μm is laminated (refer to  FIG. 1(   c )) each on the front surface and rear surface of the above-described hard core material  1  via heat resistant resin layers  31 ,  32  having a film thickness of 0.1 mm (corresponding to adhesive layers for bonding the copper layer  4 ) and hot pressing is performed, whereby the laminate  6  in which the copper layer  4  is bonded to both surfaces of the hard base material  5  is fabricated (refer to  FIG. 1(   d )). 
     In this embodiment, a bonding sheet  31  having a layer thickness of 0.1 mm and a glass epoxy resin sheet (a prepreg)  32  having a layer thickness of 0.1 mm were used as the heat resistant resin layers  31 ,  32 . 
     And the copper layer  4  was laminated on the front surface of the hard core material  1  in which the heat resistant resin material  2  is buried in the gap portion  1 A via the bonding sheet  31  and, at the same time, the copper layer  4  was laminated on the rear surface of the hard core material  1  via the glass epoxy resin sheet (the prepreg)  32  and hot pressed, whereby the laminate  6  in which the copper layer  4  is bonded to both surfaces of the hard base material  5  was fabricated. 
     Incidentally, it is also possible to fabricate a laminate obtained by laminating the copper layer  4  on both surfaces of the hard core material  1  via a bonding sheet or a laminate obtained by laminating the copper layer  4  on both surfaces of the hard core material  1  via a glass epoxy resin sheet (a prepreg). 
     When hot pressing is performed, the heat resistant resin layers  31 ,  32  (bonding sheets or glass epoxy resin sheets (prepregs)) cure thermally and the heat resistant resin layers  31 ,  32  become bonded to (become integral with) the hard core material  1 , whereby the hard base material  5  having a layer thickness of 0.6 mm is formed and, at the same time, the copper layer  4  becomes bonded via the heat resistant resin layers  31 ,  32 , with the result that it is possible to obtain the laminate  6  in which the copper layer  4  is bonded to both surfaces of the hard base material  5 . 
     Incidentally, when a glass epoxy resin sheet (a prepreg) is laminated on the hard core material  1  formed from a glass epoxy resin and hot pressing is performed, the hard core material  1  and the glass epoxy resin sheet (the prepreg) become integral with each other. 
     Furthermore, in this embodiment, as shown in the plan views of  FIGS. 2(   a ) to  2 ( c ), by burying the heat resistant resin material  2  beforehand in the gap portion  1 A formed in the hard core material  1 , it is possible to keep the shape of the gap portion  1 A during hot pressing. Also, the pressure during hot pressing become equal and the laminate  6  can be fabricated without the formation of a recess in the gap portion  1 A. 
     As shown in  FIG. 2(   a ), the gap portion  1 A which is obtained by removing part of the core material  1  in groove form was provided in the middle part of the hard core material  1 , the heat resistant resin material  2  was buried in this gap portion  1 A, and the heat resistant resin layers  31 ,  32  were laminated on the front surface and rear surface of the hard core material. 
     Incidentally, in the embodiment shown in  FIG. 2(   a ), the groove-shaped gap portion  1 A was formed by removing part of the core material  1 , the heat resistant resin material  2  was buried in this gap portion  1 A, and the heat resistant resin layers  31 ,  32  were laminated on the front surface and rear surface of the core material. However, it is also possible to use multiple hard core materials  1  and to arrange the core materials at specified intervals so as to form core materials  1  having a gap portion  1 A. 
     It is also possible to laminate a heat resistant resin layer  32 ′, in which a notch  32 A similar to the above-described gap portion  1 A is made, on the rear surface of the core material  1  in which the heat resistant resin material  2  is buried in the gap portion  1 A and to laminate the copper layer  4  via the heat resistant resin  32 ′ (refer to  FIGS. 4(   a ) to  4 ( d )). 
     By laminating the copper layer  4  on both surfaces of the hard core material  1 , in which the heat resistant resin material  2  is buried in the gap portion  1 A, via the above-described heat resistant resin layers  31 ,  32 , and performing hot pressing, it is possible to fabricate the laminate  6  which is obtained by bonding the copper layer  4  to the hard base material  5 , with the shape of the gap portion  1 A formed in the hard core material  1  kept and without the formation of a recess in the above-described gap portion  1 A. 
     And in this embodiment, after the formation of the circuit  14  and a through hole  7  (a via through hole  7   a  and a mounting through hole  7   b ) in the above-described laminate  6 , the edge portions of the laminate  6  were cut (refer to  FIG. 2(   b )) and the heat resistant resin material  2  buried in the gap portion  1 A was removed, whereby the bending rigid printed wiring board  10  in which the bent portion  10 A is arranged so as to traverse the middle of the substrate was obtained (refer to  FIG. 2(   c )). Incidentally, before the cutting of the edge portions, the heat resistant resin material  2  may be removed from the gap portion  1 A. 
     According to this embodiment, as shown in  FIGS. 3(   a ) to  3 ( d ), which illustrate the manufacturing process of a rigid printed wiring board, arbitrary circuits  14  are formed on the front surface and rear surface of the hard base material  5  by etching the laminate  6  and the through hole  7  (the via through hole  7   a  which ensures the conducting properties of the circuits formed on the front surface and rear surface of the substrate and the mounting through hole  7   b  for providing the connection terminals at prescribed positions) is formed. 
     And after that, the heat resistant resin material  2  buried in the gap portion  1 A of the hard core material  1  is removed along with the heat resistant resin layer  32  laminated on the rear surface of the heat resistant resin material  2 , whereby the bent portion  10 A obtained by reducing the thickness of the hard base material  5  in part is formed. 
     In the embodiment shown in  FIGS. 3(   a ) to  3 ( d ), a hole was made at a necessary position of the laminate  6  obtained by bonding the copper layer  4  on both surfaces of the hard base material  5  and this holed place (a through hole of the substrate) was plated, whereby the through hole  7  (the via through hole  7   a  which ensures the conducting properties of the copper layers  4  formed on both surfaces of the hard base material and the mounting through hole  7   b  for providing the connection terminals at prescribed positions) was formed (refer to  FIG. 3(   a )) and the above-described laminate  6  was etched, whereby the arbitrary circuits  14  were formed on both surfaces of the above-described hard base material  5  (refer to  FIG. 3(   b )). 
     Incidentally, in etching the laminate  6  and forming the arbitrary circuits  14  on the rear surface of the hard base material  5 , the copper layer  4  at a position corresponding to the gap portion  1 A of the hard core material  1  (on the rear surface of the heat resistant resin material  2 ) is removed by etching beforehand (an exposed portion  8 ). 
     And the heat resistant resin layer  32  was cut in the above-described exposed portion  8  and removed along with the heat resistant resin material  2  buried in the gap portion  1 A, whereby the bent portion  10 A obtained by partially reducing the thickness of the hard base material  5  was formed (refer to  FIG. 3(   d )). 
     That is, by removing the heat resistant resin material  2  buried in the gap portion  1 A along with the heat resistant resin layer  32  on the rear surface, a thin-walled portion consisting of the heat resistant resin layer  31  (bonding sheet) having a film thickness of 0.1 mm, which is a single layer, is formed in part of the hard base material  5  and the rigid printed wiring board can be bent in this thin-walled portion (the bent portion  10 A). 
     In the bending rigid printed wiring board  10  in this embodiment, on the front surface of the thin-walled portion consisting of the heat resistant resin layer  3  (the bonding sheet  31 ), which is a single layer, there is formed the circuit  14  made by etching the copper layer  4  having a layer thickness of 200 μm to 600 μm and it is ensured that circuits formed on the front surface of the hard base material  5  are connected together, the hard base material being arranged right and left, with the bent portion  10 A interposed. 
     Next, with reference to  FIGS. 4(   a ) to  4 ( d ), a description will be given of a method of manufacturing a bending rigid printed wiring board  10  which involves laminating a conductor layer  4  on the front surface of a hard core material  1  in which a heat resistant resin material  2  is buried in a gap portion  1 A via a heat resistant resin layer  31 , at the same time laminating a conductor layer  4  on the rear surface of the hard core material  1  via a heat resistant resin layer  32 ′ in which a notch  32 A similar to the above-described gap portion  1 A is made, performing hot pressing, whereby a laminate  61  in which the conductor layers  4  are bonded to both surfaces of the hard base material  51  is fabricated, and removing the heat resistant resin material  2  buried in the gap portion  1 A from this laminate  61 . 
     In the embodiment shown in  FIGS. 4(   a ) to  4 ( d ), in the same way as with the embodiment shown in  FIGS. 1(   a ) to  1 ( d ), in the center part of the flat-plate-like hard core material  1  which is made of a glass epoxy resin and has a layer thickness of 0.4 mm, there is provided the gap portion  1 A which is formed by removing part of the core material in groove form. 
     And in this embodiment, a heat resistant resin material  2 , such as a Teflon (registered trademark) sheet having a film thickness of 0.5 mm and silicone rubber, was buried in the gap portion  1 A of the hard core material  1 , and a convex portion having a height of 0.1 mm was formed, the convex portion being such that the heat resistant resin material  2  protrudes from the rear surface of the gap portion  1 A. Also, the notch  32 A corresponding to the above-described convex portion was formed in the heat resistant resin layer  32 ′ laminated on the rear surface of the hard core material  1 , and the copper layer  4  having a layer thickness of 200 to 600 μm was laminated each on the front surface and rear surface of the hard core material  1 , in which the heat resistant resin material  2  is buried in the gap portion  1 A, via the heat resistant resin layers  31 ,  32 ′ (refer to  FIG. 4(   a )). 
     When the copper layer  4  is laminated, via the heat resistant resin layer  31 , on the front surface of the hard core material  1 , in which the heat resistant resin material  2  is buried in the gap portion  1 A, the copper layer  4  is laminated on the rear surface via the heat resistant resin layer  32 ′ in which the notch  32 A is made, and hot pressing is performed, the above-described heat resistant resin layers  31 ,  32 ′ cure thermally and become bonded to (become integral with) the hard core material  1  and the hard base material  51  having a layer thickness of 0.6 mm is formed and, at the same time, the copper layer  4  becomes bonded via the above-described heat resistant resin layers  31 ,  32 ′, whereby it is possible to obtain the laminate  61  in which the copper layer  4  is laminated on both surfaces of the hard base material  51 . (Refer to  FIG. 4(   b ).) 
     Incidentally, in this example, the copper layer  4  is laminated on the rear surface of the heat resistant resin material  2  buried in the gap portion  1 A without the interposition of the heat resistant resin layer  32 ′. 
     After that, arbitrary circuits  14  are formed on the front surface and rear surface of the hard base material  51  by etching the laminate  61  and at the same time, a through hole  7  (a via through hole  7   a  which ensures the conducting properties of the circuits formed on the front surface and rear surface of the substrate and a mounting through hole  7   b  for providing connection terminals at prescribed positions) is formed. (Refer to  FIG. 4(   c ).) 
     Incidentally, in etching the laminate  61  and forming the arbitrary circuits  14  on the rear surface of the hard base material  5 , the copper layer  4  on the rear surface of the heat resistant resin material  2  buried in the gap portion  1 A is removed by etching beforehand (an exposed portion  8 ). 
     And in this embodiment, as shown in  FIG. 4(   d ), by removing the heat resistant resin material  2  buried in the gap portion  1 A of the hard core material  1 , a bent portion  10 A which is obtained by reducing the thickness of part of the hard base material  51  is formed. 
     In a both-side wiring board in which the circuits  14  are formed on the front surface and rear surface of the hard base material  51 , a bending rigid printed wiring board  10  provided with a bent portion  10 A which is obtained by partially reducing the thickness of the hard base material  51  has been described above. However, the bending rigid printed wiring board is not limited to the both-side wiring board. 
     For example, as shown in  FIGS. 5(   a ) to  5 ( c ), a laminate  62  which is obtained by laminating, via a heat resistant resin layer  3 , a conductor layer  4  on the front surface (a single side) of a hard core material  1 , in which a heat resistant resin material  2  is buried in a gap portion  1 A, is used (refer to  FIG. 5(   a )), and, by etching the laminate, circuits  14  are formed on the front surface of the hard base material  52  constituted by the hard core material  1  and the heat resistant resin layer  3  (refer to  FIG. 5(   b )). At the same time, the heat resistant resin material  2  buried in the gap portion  1 A of the hard core material  1  is removed and a thin-walled portion constituted by only a heat resistant resin layer  3 , which is a single layer, is provided in part of the hard base material  52 , whereby it is possible to obtain a bending rigid printed wiring board (a single-side wiring board) having a bent portion  10 A formed by partially reducing the thickness of the hard base material  52  (refer to  FIG. 5(   c )). 
     Also, for example, as shown in  FIGS. 6(   a ) to  6 ( e ), by using a core material  11  in the form of a shielded plate, it is possible to obtain a bending rigid printed wiring board (a multilayer wiring board) having a bent portion  10 A obtained by partially reducing the thickness. 
     As shown in  FIGS. 6(   a ) to  6 ( d ), a hard core material  1  is laminated, via a heat resistant resin layer  31 , on the front surface of a rigid wiring board in which circuits  14  are formed on the front surface of a hard core material  1  and hot pressing is performed, whereby a hard core material  11  in the form of a shielded plate is fabricated (refer to  FIG. 6(   a )), a gap portion  1 A is formed by removing part of the hard core material  11  in the form of a shielded plate (refer to  FIG. 6(   b )), a conductor layer  4  is laminated, via a heat resistant resin layer  31 , on the front surface of the core material  11  in the form of a shielded plate in which a heat resistant resin material  2  is buried in the above-described gap portion  1 A, a conductor layer  4  is laminated on the rear surface via a heat resistant resin layer  32 ′ in which a notch  32 A is made, and hot pressing is performed, whereby a laminate  63  in which the conductor layers  4  are laminated on both surfaces of a hard base material  53  is fabricated (refer to  FIG. 6(   c )). And the circuits  14  are formed on the front surface and rear surface of the hard base material  53  by etching the above-described laminate  63  and at the same time, the conductor layer  4  on the rear surface of the gap portion  1   a  is removed by etching (refer to  FIG. 6(   d )) and furthermore, the heat resistant resin material  2  buried in the above-described gap portion  1 A is removed, whereby it is possible to obtain a multilayer wiring board having a bent portion  10 A which is formed by partially reducing the thickness (refer to  FIG. 6(   e )). 
     Next, with reference to  FIGS. 7(   a ) to  7 ( d ) to  FIGS. 12(   a ) and  12 ( b ), a description will be given of a method of manufacturing a bending rigid printed wiring board in which a circuit for large current and a circuit for small current are formed on the same substrate by forming conductor parts ( 4 A,  4 B) having different layer thicknesses on the same surface of a conductor layer  4 . 
       FIGS. 7(   a ) to  7 ( d ) are diagrams to explain a method of forming conductor layer  4  which is constituted by a thick conductor portion  4 A having a thickness of not less than 175 μm, preferably 200 to 600 μm, and a thin conductor portion  4 B having a thickness of not more than 105 μm, preferably 18 to 70 μm. In this embodiment, a conductor plate  40  having a thickness of not less than 175 μm, preferably 200 to 600 μm and a conductor laminate material  44  which is formed to suit the shape of the above-described hole portion and the thickness of the conductor plate (a conductor laminate material  44  formed by laminating a thin conductor  43 ) are used. 
     First, as shown in  FIG. 7(   a ), the conductor plate  40  having a thickness of not less than 175 μm, preferably 200 to 600 μm is prepared, and a hole portion  41  is formed in this conductor plate  40 . 
     As shown in  FIG. 7(   b ), the conductor laminate material  44 , which is obtained by laminating a thin conductor  43  (a conductor  43  having a thickness of not more than 100 μm, preferably 18 to 70 μm) on an insulating base material  42 , is formed to suit the thickness of the above-described conductor plate  40  and the shape of the hole portion  41 . 
     And as shown in  FIG. 7(   c ), the conductor laminate material  44  obtained by laminating the thin conductor  43  is buried (embedded) in the hole portion  41  of the conductor plate  40 . And the conductor plate  40 , in which the conductor laminate material  44  is buried in the hole portion  41 , is laminated on a core material  1  via a heat resistant resin layer ( 31  or  32 ) and hot pressing is performed, whereby as shown in  FIG. 7(   d ), the conductor portions having different layer thicknesses  4 A and  4 B are formed on the same surface of the conductor layer  4 . That is, upon the same surface of the conductor layer  4 , there are formed the thick conductor portion  4 A having a thickness of not less than 175 μm, preferably 200 to 600 μm, and the thin conductor portion  4 B having a thickness of not more than 105 μm, preferably 18 to 70 μm. Incidentally, in a bent portion  10 A of a bending rigid printed wiring board, the conductor plate  40  is laminated so that the thick conductor portion  4 A having a thickness of not less than 175 μm can be provided. 
     Subsequently, with reference to  FIGS. 8(   a ) to  8 ( c ) to  FIGS. 12(   a ) and  12 ( b ), a description will be given of a method of manufacturing a bending rigid printed wiring board in which a circuit for large current and a circuit for small current are formed on the same surface. 
     In this embodiment, by using the technique shown in  FIGS. 7(   a ) to  7 ( d ), a bending rigid printed wiring board  10  is manufactured, in which a circuit for large current  14   a  having a thickness of not less than 175 μm, preferably 200 to 600 μm (for example, an inner circuit of an electric connection box) and a circuit for small current  14   b  having a thickness of not more than 105 μm, preferably 18 to 70 μm (for example, an electronic circuit) are formed. 
     In this embodiment, as shown in  FIG. 8(   a ), there are prepared a conductor plate  40  having a thickness of not less than 200 μm and a conductor laminate parent material  44 ′ having the same thickness as this conductor plate. Incidentally, a conductor laminate parent material obtained by laminating thin conductors  43   a ,  43   b  having a thickness of 18 to 70 μm on the front surface and rear surface of an insulating base material  42  was used as the conductor laminate parent material  44 ′. 
     And as shown in  FIG. 8(   b ), a hole portion  41  is formed by partially boring the conductor plate  40  and at the same time, as shown in  FIG. 8(   c ), a conductor laminate  44  is cut out of the conductor laminate parent material  44 ′ to suit the shape of a hole portion  41  of the above-described conductor plate  40 . 
     In this embodiment, two hole portions  41  were made each in two conductor plates  40  and four conductor laminate materials  44  were cut out of one conductor laminate parent material  44 ′ to suit the shape of the hole portion  41 . 
     And as shown in the sectional view of  FIG. 9(   a ), the conductor laminates  44 , in which the thin conductors  43   a ,  43   b  are laminated on the front surface and the rear surface, were buried (embedded) in their respective hole portions  41 , and as shown in the plan view of  FIG. 9(   b ), the thin conductors  43   a ,  43   b  having a thickness of 18 to 70 μm were partially formed on the same surface of the conductor plate  40  having a thickness of not less than 200 μm. Incidentally because the conductor plate  40  and the conductor laminate material  44  have the same thickness, the front surface of the conductor and the thin conductors  43   a ,  43   b  obtain the same height. 
     In this embodiment, the thin conductor  43   b  on one side of the above-described conductor laminate material  44  was etched, circuits for small current ( 14   b   2 ,  14   b   5 ) were formed beforehand, and the conductor laminate materials  44  were buried in the hole portions  41  of the conductor plates  40  so that these circuits for small current ( 14   b   2 ,  14   b   5 ) are arranged on the inner side. That is, it was ensured that the circuits for small current ( 14   b   2 ,  14   b   5 ) are formed on a thin conductor  43   b  which are arranged on the inner side when the conductor plates  40 , in which the conductor laminate material  44  is buried, are each laminated on the front surface and rear surface of the hard core material via heat resistant resin layers  31 ,  32 , are formed beforehand. 
     In the manufacturing process of a bending rigid printed wiring board, in this embodiment, a hard core material obtained by laminating thin conductors  43   c ,  43   d  on the front surface or rear surface of the core material was used as the hard core material obtained by removing a place corresponding to a bent portion (refer to  FIG. 10(   a )). And a heat resistant resin material  2  is buried in a gap portion (a portion from which the hard core material has been removed)  1 A of the hard core material  1 ′ on which the thin conductors  43   c ,  43   d  are laminated. Incidentally, circuits for small current ( 14   b   3 ,  14   b   4 ) were formed by etching the thin conductors  43   c ,  43   d  on the front surface or rear surface of the hard core material  1 ′. 
     And as shown in  FIGS. 11(   a ) to  11 ( d ), the conductor plates  40 , in which the conductor laminate material  44  is buried in the hole portion  41 , are laminated, via the heat resistant resin layers  31 ,  32 , on the front surface and rear surface of the hard core material  1 ′ in which the heat resistant resin material  2  is buried in the gap portion  1 A and hot pressing is performed, whereby a laminate  64  is fabricated (refer to  FIGS. 11(   a ) and  11 ( b )). 
     As shown in  FIG. 11(   b ), a thick conductor portion  4 A having a thickness of not less than 200 μm and a thin conductor portion  4 B (a thin conductor  43   a ) having a thickness of 18 to 70 μm are formed on the conductor layers  4  on the front surface and rear surface of the laminate  64  fabricated by laminating the conductor plate  40 , in which the conductor laminate material  44  is buried in the hole portion  41 . 
     And as shown in  FIG. 11(   c ), circuits for small current  14   b   1 ,  14   b   6  having a thickness of 18 to 70 μm were formed by etching the above-described thin conductor portion  4 B (the thin conductor  43   a ) and at the same time, a circuit for large current  14   a  having a thickness of not less than 200 μm was formed by etching the above-described thick conductor portion  4 A. Thus, the circuit for large current  14   a  and the circuits for small current  14   b   1 ,  14   b   6  were formed on the same surface. Also, through holes  7  (via through holes for ensuring the conducting properties of circuits formed on the front surface and rear surface of the substrate and mounting through holes for providing connection terminals at prescribed positions) were formed in the laminate  64 . 
     Incidentally, in forming the arbitrary circuit (the circuit for large current)  14   a  by etching the thick conductor portion  4 A of the conductor  4  having a thickness of not less than 200 μm, the conductor layer  4  of a place corresponding to the gap portion  1 A of the hard core material  1 ′ (on the rear surface of the heat resistant resin material  2 ) is removed beforehand (an exposed portion  8 ). And as shown in FIG.  11 ( d ), the heat resistant resin material  2  buried in the gap portion  1 A of the hard core material  1 ′ is removed along with the heat resistant resin layer  32  on the rear surface, whereby a bent portion  10 A is formed. 
       FIGS. 12(   a ) and  12 ( b ) are diagrams which show a bending rigid printed wiring board in which a circuit for large current and a circuit for small current are formed on the same surface,  FIG. 12(   a ) being a sectional view and  FIG. 12(   b ) being a plan view. 
     As shown in  FIG. 12(   a ), in a bending rigid printed wiring board of this embodiment, a circuit for large current  14   a  having a thickness of not less than 200 μm and circuits for small current  14   b   1 ,  14   b   6  having a thickness of 18 to 70 μm are formed on the same surface, with the height of these circuits being flush with each other. 
     As shown in  FIG. 12(   b ), the circuit for large current  14   a  and the circuits for small current  14   b   1 ,  14   b   6  are formed on the front surface (the outermost layer) of the bending rigid printed wiring board, and the electrically conducting properties of these circuits are ensured via through holes  7  and circuits formed on the inner side (circuits for small current  14   b   3 ,  14   b   4 ). 
     The electrically conducting properties of the circuits for small current ( 14   b   1 ,  14   b   2 ,  14   b   5 ,  14   b   6 ) formed by etching the thin conductors  43   a ,  43   b  of the conductor laminate material  44  buried in the hole portion  41  of the conductor plate  40  the circuit for large current  14   a  formed by etching the conductor plate  40  are ensured, as shown in  FIG. 12(   a ), by the medium of a through hole  7  (a via through hole) provided in the section where the circuits for small current ( 14   b   1 ,  14   b   2 ,  14   b   5 ,  14   b   6 ) are formed, a through hole  7  (via through hole) provided in the section where the circuit for large current  14   a  is formed, and the circuits for small current ( 14   b   3 ,  14   b   4 ) provided on the front surface or rear surface of the core material  1 ′. 
     Incidentally, the front surface and rear surface of the bending rigid printed wiring board are coated with a resist (an insulating material)  9  in order to protect the circuits. 
     Next, with reference to  FIGS. 13(   a ) to  13 ( d ), a description will be given of a method of manufacturing a substrate board in which connection terminals  20  are provided at prescribed positions in a rigid printed wiring board. 
     In this embodiment, a bending rigid printed wiring board  10  having a bent portion  10 A which is formed by partially reducing the thickness of a hard base material  5  was used, and after the installation of connection terminals  20  to the front surface of this bending rigid printed wiring board  10 , the bending rigid printed wiring board  10  was bent at a bent portion  10 A, whereby a substrate circuit in which the connection terminals  20  are provided at prescribed positions on both surfaces was manufactured. 
     In the bending rigid printed wiring board  10  of this embodiment, as shown in  FIG. 13(   a ), circuits  14  are formed on the front surface and rear surface of the hard base material  5  and at the same time, via through holes  7   a  for ensuring the electrically conducting properties of the circuits formed on the above-described front surface and rear surface are formed. In the middle of the substrate, a bent portion  10 A which is obtained by partially reducing the thickness of the hard base material  5  is formed and at the same time, in the substrate (the base material  5 ) arranged right and left with the bent portion  10 A interposed, there are formed mounting through holes  7   b  for arranging the connection terminals  20  at prescribed positions. 
     Incidentally, the circuit  14  is formed on the front surface of the bent portion  10 A which is obtained by partially reducing the thickness of the hard base material  5  and this ensures the connection of the circuits formed on the front surface of the substrate (the base material  5 ) arranged right and left with the bent portion  10 A interposed. 
     Furthermore, in the rigid printed wiring board  10  of this embodiment, the circuit surfaces are coated with the resist (the insulating material)  9 . 
     Incidentally, when the substrate in which the front surface of the bent portion  10 A is coated with the resist  9  is bent in the above-described bent portion  10 A, cracking and the like may occur in the resist  9  which coats the bent portion  10 A due to stresses applied during the bending and, therefore, the front surface of the bent portion  10 A of the rigid printed wiring board  10  shown in  FIG. 13(   a ) is not coated with the resist  9 . 
     And in this embodiment, after the connection terminals  20  are press fitted into the mounting through holes  7   b  and the connection terminals  20  are provided at prescribed positions on the front surface of the rigid printed wiring board  10  (refer to  FIG. 13(   b )), on the rear surface of the rigid printed wiring board  10  leading end portions  20 A of the press-fitted connection terminals  20  are soldered  21 , whereby the connection terminals  20  are fixed to the rigid printed wiring board  10  (refer to  FIG. 13(   c )). 
     After that, by bending the bent portion  10 A of the rigid printed wiring board  10  in which the connection terminals  20  are provided at prescribed positions on the front surface by use of a bending jig  30 , it is possible to easily manufacture a substrate circuit in which the connection terminals  20  are provided at prescribed positions on both surfaces as shown in  FIG. 13(   a ). 
     Incidentally, it is also possible to adopt the following method. That is, a circuit  14 , via through holes  7   a , and mounting through holes  7   b  are formed in a laminate  6  which is obtained by laminating a copper layer  4  on a hard core material  1  in which a heat resistant resin material  2  is buried in a gap portion  1 A, the connection terminals  20  are press fitted into the above-described mounting through holes  7   b  and soldered, whereby the connection terminals  20  are provided at prescribed positions on the front surface. After that, the heat resistant resin material  2  buried in the above-described gap portion  1 A is removed and a bent portion  10 A which is obtained by partially reducing the thickness of the hard base material  5  is formed and the rigid printed wiring board  10  is bent thereafter in the above-described bent portion  10 A, whereby a substrate circuit in which the connection terminals  20  are provided at prescribed positions on both surfaces is manufactured. 
     The substrate circuit shown in  FIG. 14(   a ) is fabricated by bending a rigid printed wiring board  10 , in which the connection terminals  20  are provided at prescribed positions on the front surface, in the bent portion  10 A. Therefore, the degree of freedom of the positions of the connection terminals  20  which are provided at prescribed positions on the front surface and the rear surface is high and besides it is necessary only that the soldering step for fixing the connection terminals  20  to the substrate be performed once. Furthermore, for the circuits which are formed in the substrate (base material  5 ) which is arranged, with the bent portion  10 A interposed, electrical connection is ensured by the circuit  14  formed on the front surface of the bent portion  10 A. 
     Furthermore, in the substrate circuit shown in  FIG. 14(   b ), after a rigid printed wiring board  10  in which the connection terminals  20  are provided at prescribed positions on the front surface, is bent in the bent portion  10 A, an insulating film  91  is provided on the front surface of the bent portion  10 A. 
     In this embodiment, in order to prevent cracking and the like from occurring in the resist  9  due to stresses applied during the bending, the rigid printed wiring board in which the bent portion  10 A is not coated with the resist  9  was bent, and after that, the insulating film  91  was provided on the front surface of the bent portion  10 A in order to protect the circuit  14  formed on the front surface of the above-described bent portion  10 A.