Patent Publication Number: US-2013250562-A1

Title: Wiring board device, luminaire, and manufacturing method of the wiring board device

Description:
INCORPORATION BY REFERENCE 
     The present invention claims priority under 35 U.S.C. §119 to Japanese Patent Application No. 2012-068333 filed on Mar. 23, 2012. The content of the application is incorporated herein by reference in their entirety. 
     FIELD 
     Embodiments described herein relate generally to a wiring board device including a connector, a luminaire and a manufacturing method of the wiring board device. 
     BACKGROUND 
     Hitherto, for example, in an LED module used in a luminaire, a wiring board device in which a wiring pattern is formed on one surface of a board is used. An LED element is electrically connected to the wiring pattern of the board, and a connector for power feeding is soldered thereto. A cable from a lighting device is connected to the connector. Then, lighting power from the lighting device is supplied to the LED element through the cable, the connector and the wiring pattern, and the LED element is turned on. 
     Besides, in the LED module, the output is increased, and the board is required to have high heat resistance and high heat radiation property as the output increases. In order to satisfy this request, a ceramic board is often used. Also in the ceramic board, similarly to a general printed wiring board, a wiring pattern is generally formed on one surface of the ceramic board by printing. Accordingly, a connector is also soldered and placed on the wiring pattern of the ceramic board. 
     When the ceramic board is used, even if the temperature of the ceramic board becomes high with the increase of output and by heat generated by the LED element, since the ceramic board has high heat resistance, there is no problem. However, since the heat is filled in the ceramic board and the temperature of the ceramic board is liable to become high, the temperature of the solder connecting the connector to the ceramic board is also liable to become high. 
     Since thermal expansion coefficients of a resin portion of the connector, a metal portion of the connector and the ceramic board are different from each other between the connector and the ceramic, stress is applied to the solder due to the difference between the thermal expansion coefficients, and a crack becomes liable to occur in the solder. When the crack occurs in the solder, there is a problem that defective connection of the connector occurs. 
     Exemplary embodiments described herein provide a wiring board device, a luminaire and a manufacturing method of the wiring board device, in which even if the temperature of a ceramic board becomes high, influence on a connector can be reduced and the occurrence of defects due to heat can be prevented. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a sectional view of a wiring board device of an embodiment. 
         FIG. 2  is a front view of the wiring board device. 
         FIG. 3  is a sectional view of the wiring board device. 
         FIGS. 4(   a ) to  4 ( c ) are sectional views showing a manufacturing method of the wiring board device in order. 
         FIG. 5  is a perspective view of a luminaire using the wiring board device. 
     
    
    
     DETAILED DESCRIPTION 
     In general, according to one embodiment, a wiring board device includes a common member. A ceramic board and a connector are placed on the common member. A wiring pattern of the ceramic board and the connector are electrically connected by wiring. 
     According to this structure, since the ceramic board and the connector are placed on the common member, even if the temperature of the ceramic board becomes high, influence on the connector can be reduced, and the occurrence of defects due to heat can be prevented. 
     Hereinafter, an embodiment will be described with reference to  FIG. 1  to  FIG. 5 . 
       FIG. 5  shows a luminaire  10 . The luminaire  10  is, for example, a floodlight used for lighting-up. The luminaire  10  includes an equipment main body  11 , and a floodlight window  12  is provided in the equipment main body  11 . Plural light-emitting modules  13  facing the floodlight window  12  are housed in the equipment main body  11 . A lighting device  14  to supply lighting power to the light-emitting module  13  is housed at a lower part in the equipment main body  11 . The lighting device  14  supplies the lighting power to the plural light-emitting modules  13 , so that the plural light-emitting modules  13  are turned on, and light is emitted from the floodlight window  12 . 
       FIG. 1  and  FIG. 2  show the light-emitting module  13 . The light-emitting module  13  includes a wiring board device  20 . 
     The wiring board device  20  includes a square ceramic board  21 . A front side of the ceramic board  21  is a first surface  21   a , and a back side thereof is a second surface  21   b . A first electrode layer  22   a  is formed on the first surface  21   a , and a first copper plated layer  23   a  as a copper plated layer  23  is formed on the first electrode layer  22   a . A wiring pattern  24  having a specific shape is formed of the first electrode layer  22   a  and the first copper plated layer  23   a . On the other hand, a second electrode layer  22   b  is formed on substantially the whole area of the second surface  21   b , and a second copper plated layer  23   b  is formed on the second electrode layer  22   b . Further, metal plated layers  25  to protect the copper plated layers  23   a  and  23   b  are formed on the surfaces of the copper plated layers  23   a  and  23   b.    
     The electrode layers  22   a  and  22   b  are formed by sputtering of a metal such as titanium. The copper plated layers  23   a  and  23   b  are formed in such a manner that a current is applied to the electrode layers  22   a  and  22   b  in a state where the ceramic board  21  is immersed in a copper plating solution of a plating device and copper plating is applied onto the electrode layers  22   a  and  22   b . Besides, the metal plated layer  25  is formed of, for example, nickel/gold plating or nickel/lead/gold plating. A DPC (Direct Plated Copper) board  26  is formed of the ceramic board  21 , the electrode layers  22   a  and  22   b , the copper plated layers  23   a  and  23   b , and the metal plated layer  25 . 
     The first electrode layer  22   a  and the second electrode layer  22   b  are formed to have the same thickness, and the first copper plated layer  23   a  and the second copper plated layer  23   b  are formed to have the same thickness. The thickness of the first electrode layer  22   a  is about 1 μm, the minimum width of the first copper plated layer  23   a  (a wiring pattern  24  through which current flows) is 50 to 75 μm, and the thickness thereof is 35 to 100 μm (preferably, 50 to 75 μm). Incidentally, when the wiring pattern is formed by printing, the thickness of the wiring pattern is at most about 10 μm. 
     As shown in  FIG. 2 , the wiring pattern  24  includes a positive and negative pair of electrode parts  27  to receive lighting power from the outside, and plural wiring parts  28  are formed in parallel between the pair of electrode parts  27 . Plural LED elements  29  are mounted on the adjacent wiring parts  28 . 
     As shown in  FIG. 3 , the plural LED elements  29  are of a type, such as a flip chip type, in which a pair of electrodes are provided on the back side. The pairs of electrodes of the plural LED elements  29  are electrically connected to the first copper plated layer  23   a  by solder die bond layers  30 . Incidentally, the LED element may be such that an electrode is provided on the front surface side as in a face-up type, and the electrode of the LED element and the wiring pattern  24  are connected by wire bonding. 
     A white organic resist layer  31  containing epoxy resin as a main component is formed on the first surface  21   a  side including the first copper plated layer  23   a . A white inorganic resist ink layer  32  containing ceramic as a main component is formed on the organic resist layer  31 . The surfaces of the organic resist layer  31  and the inorganic resist ink layer  32  are formed as a reflecting surface  33  to reflect light emitted from the plural LED elements  29 . 
     Besides, an annular reflecting frame  34  is formed on the first surface  21   a  side so as to surround a mount area of the plural LED elements  29 . A sealing resin  35  to seal the plural LED elements  29  is filled inside the reflecting frame  34 . The sealing resin  35  contains a phosphor which is excited by the light generated by the plural LED elements  29 . For example, when the light-emitting module  13  emits white light, the LED element  29  emitting blue light and the phosphor mainly emitting yellow light are used. The blue light generated by the LED element  29  is mixed with the yellow light generated by the phosphor which is excited by the blue light generated by the LED element  29 , and white light is emitted from the surface of the sealing resin  35 . Incidentally, the LED element  29  and the phosphor, which emit lights of colors corresponding to the color of irradiated light, are used. 
     Besides, the light-emitting module  13  is placed on one surface of a heat spreader  37  as a common member  36 . That is, the second copper plated layer  23   b  of the DPC board  26  is fixed to the one surface of the heat spreader  37  by a solder layer  38  and is thermally connected thereto. The heat spreader  37  includes a copper plate  39  having a thickness of 0.1 to 3 mm, and a metal plated layer  40  of, for example, nickel is formed on the whole surface of the copper plate  39 . Attachment holes  41  for fixing to a heat radiation part of the luminaire  10  using screws are formed at four corners of the heat spreader  37 . 
     Besides, as shown in  FIG. 1  and  FIG. 2 , a connector  44  is placed on the one surface of the heat spreader  37  adjacent to the light-emitting module  13 . The connector  44  includes a case  45  made of a synthetic resin having insulating properties, and a connector terminal  46  arranged in the case  45 . A pair of positive and negative terminal parts  47  electrically connected to the connector terminal  46  are provided outside the case  45 . The connector  44  is fixed to the heat spreader  37  by a fixing unit  48  in an insulated state. A screw  49  to be screwed into the heat spreader  37  through the case  45  is used as the fixing unit  48 . Incidentally, as the fixing unit  48 , an adhesive to bond the case  45  to the heat spreader  37  may be used in stead of the screw  49 , and any fixing unit other than solder may be used. 
     The respective terminal parts  47  and the respective electrode parts  27  of the light-emitting module  13  are electrically connected to each other by wirings  50 . A wire  51 , such as a circular wire having a section with a diameter of 300 to 500 μm or a ribbon wire having a width of 0.1 to 0.2 mm and a thickness of 100 μm, is used as each of the wirings  50 . The wire  51  is ultrasonically welded to the terminal part  47  and the electrode part  27  by wire bonding, and the electrical connection is made. Aluminum having high reflectivity is used as the material of the wire  51 . 
     A thickness D 1  of the DPC board  26  including the ceramic board  21  is about 1 mm, and a thickness D 2  of the connector  44  is about 2 to 5 mm. The thickness D 1  of the DPC board  26  (the ceramic board  21 ) is thinner than the thickness D 2  of the connector  44 . 
     An interval L 1  of, for example, about 1.2 mm is provided between the ceramic board  21  and the connector  44 . The interval L 1  is smaller than a creeping distance L 2  along the surface of the connector  44  (the case  45 ) between the terminal part  47  and the heat spreader  37 . 
     Besides, a creeping distance L 3  along the surface of the ceramic board  21  between the electrode part  27  of the wiring pattern  24  and the heat spreader  37  is equal to or larger than the creeping distance L 2  along the surface of the connector  44  (the case  45 ) between the terminal part  47  and the heat spreader  37 , and the relation of L 3 ≧L 2  is established. 
     Besides, in order to ensure insulation between the wire  51  and the heat spreader  37 , a spatial distance of 4 mm or more is provided between the wire  51  and the heat spreader  37 . 
     Next, a manufacturing method of the wiring board device  20  will be described with reference to  FIGS. 4(   a ) to  4 ( c ). 
     As shown in  FIG. 4(   a ), the DPC board  26  is placed on one surface of the heat spreader  37 . That is, the second copper plated layer  23   b  of the DPC board  26  is fixed to the one surface of the heat spreader  37  by the solder layer  38  and is thermally connected thereto. 
     As shown in  FIG. 4(   b ), the connector  44  is arranged on the one surface of the heat spreader  37 , the screws  49  are threaded into the heat spreader  37  through the case  45 , and the connector  44  is fixed to the one surface of the heat spreader  37 . 
     As shown in  FIG. 4(   c ), the wires  51  are ultrasonically welded to the terminal parts  47  of the connector  44  and the respective electrode parts  27  of the DPC board  26 , and the electrical connection is made. 
     Incidentally, when the DPC board  26  is placed on the one surface of the heat spreader  37 , the light-emitting module  13  may be assembled in which the LED elements  29  are already mounted on the DPC board  26 . Alternatively, after the DPC board  26  is placed on the one surface of the heat spreader  37 , the light-emitting module  13  may be assembled by mounting the LED elements  29  on the DPC board  26 . 
     Besides, as shown in  FIG. 5 , the plural light-emitting modules  13  are disposed in the equipment main body  11 . In this case, screws are threaded into the attachment holes  41  of the heat spreader  37  to fix the heat spreader to the heat radiation part of the equipment main body  11 , and the heat spreader  37  is thermally connected to the heat radiation part of the equipment main body  11 . Besides, a cable from the lighting device  14  is connector-connected to the connector  44  of the light-emitting module  13 . 
     The lighting device  14  supplies lighting power to the plural light-emitting modules  13 , so that the lighting power flows through the plural LED elements  29  through the wiring patterns  24  of the respective light-emitting modules  13 . Thus, the plural light-emitting modules  13  are turned on, and the lights from the plural light-emitting modules  13  are emitted from the floodlight window  12 . 
     The heat generated in the plural LED elements  29  at the time of lighting of the light-emitting modules  13  is efficiently conducted to the first copper plated layer  23   a , the ceramic board  21 , the second copper plated layer  23   b  and the heat spreader  37 . The heat is further efficiently conducted from the heat spreader  37  to the heat radiation part of the equipment main body  11 , and is radiated from the heat radiation part of the equipment main body  11 . 
     In this embodiment, since the ceramic board  21  and the connector  44  are placed on the common member  36 , even if the temperature of the ceramic board  21  becomes high, the influence on the connector  44  can be reduced, and the occurrence of defects due to the heat can be prevented. 
     Besides, since the common member  36  is the heat spreader  37 , the heat is efficiently conducted from the ceramic board  21  to the heat spreader  37  and can be radiated. Thus, the temperature rise of the ceramic board  21  can be reduced. 
     Besides, since the connector  44  is fixed to the common member  36  by the fixing unit  48  in the insulated state, that is, since the connector is fixed without using solder, defects caused by the use of solder and by the influence of heat can be prevented. 
     Besides, since the wires  51  as the wirings  50  are welded to the electrode parts  27  of the wiring pattern  24  and the terminal parts  47  of the connector  44 , the mechanical bonding strength is high, the electrical connection becomes stable, and a large current can be made to flow. Thus, in light-emitting module  13 , the output can be increased. 
     Further, since aluminum having high reflectivity is used as the material of the wire  51 , the light emitted from the LED element  29  is efficiently reflected, and the light extraction efficiency from the light-emitting module  13  can be improved. 
     Besides, since the DPC board  26  is used in which the copper plated layer (first copper plated layer)  23   a  is formed on the ceramic board  21 , and the wiring pattern  24  is formed of the copper plated layer (first copper plated layer)  23   a , a large current can be made to flow through the wiring pattern  24 . Thus, in the light-emitting module  13 , the output can be increased. 
     Besides, although the thickness D 1  of the ceramic board  21  (the DPC board  26 ) is thinner than the thickness D 2  of the connector  44 , since the interval L 1  exists between the ceramic board  21  (the DPC board  26 ) and the connector  44 , in the light-emitting module  13 , it can be reduced that the light emitted from the LED element  29  on the ceramic board  21  (the DPC board  26 ) is blocked by the connector  44 . 
     Further, insulation properties can be ensured by a spatial distance smaller than a creeping distance. From this, the interval L 1  as the spatial distance between the ceramic board  21  and the connector  44  can be made smaller than the creeping distance L 2  along the surface of the connector  44  between the terminal part  47  and the common member  36 . Thus, while the insulation properties are ensured, the distance between the ceramic board  21  and the connector  44  is made small, and an increase in size can be prevented. 
     The creeping distance L 3  along the surface of the ceramic board  21  between the wiring pattern  24  and the common member  36  is equal to or larger than the creeping distance L 2  along the surface of the connector  44  between the terminal part  47  and the common member  36 , and the relation of L 3 ≧L 2  is established. Accordingly, the interval L 1  as the spatial distance between the ceramic board  21  and the connector  44  can be made small. Thus, the ceramic board  21  and the connector  44  are arranged to be close to each other while keeping the insulation properties, so that miniaturization can be performed. 
     Incidentally, the common member  36  is not limited to the heat spreader  37 , and another heat radiation member such as, for example, a heat sink may be adopted. 
     Besides, the wiring board device  20  is not limited to the wiring board device for mounting the LED elements  29 , and the wiring board device  20  can be applied to a wiring board device for mounting an integrated circuit and the like, or a wiring board device for mounting electrical parts of a power supply device. 
     While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions, and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.