Patent Publication Number: US-7910947-B2

Title: Panel-shaped semiconductor module

Description:
TECHNICAL FIELD 
     The present invention relates to a panel-shaped light receiving or emitting semiconductor module and particularly to a semiconductor module comprising multiple rod-shaped semiconductor elements (semiconductor devices). 
     BACKGROUND TECHNOLOGY 
     A variety of solar batteries (solar battery modules and solar battery panels) comprising external lenses for yielding large output power by means of a small light receiving area have been proposed. However, because the larger areas are realized in silicon solar batteries and production cost of solar battery cells and solar battery modules is reduced, light collection by external lenses is less used. 
     On the other hand, in the solar battery using expensive compound semiconductors such as gallium arsenide (GaAs), light collection by external lenses is assumed to be economical and proposed in many documents. 
     The U.S. Pat. No. 4,136,436 and the U.S. Pat. No. 6,204,545 by the inventor of the present application propose a spherical or partially spherical solar battery cell made of granular silicon crystal as a technique for efficient use of expensive silicon raw material. 
     The inventor of the present application proposed in the Japanese Laid-Open Patent Publication No. 2001-168369 a solar battery module having spherical solar battery cells in which a reflecting plate is provided on the back in a close contact manner. The inventor also proposed in the International Publication No. WO03/056633 a spherical solar battery cell housed in a synthetic resin capsule having a diameter larger than the cell and filled with a synthetic resin for light collection. They have a smaller collecting power compared with use of external lenses, however they can be realized in a relatively simple structure. 
     The U.S. Pat. No. 5,482,568 discloses a micromirror solar battery in which multiple cone-shaped reflecting mirrors are provided in a case, a solar battery cell having a flat light-receiving surface is placed at the bottom of each cone, the sunlight collected by the cone illuminates the top surface of the solar battery cell, and the heat is released from the underside of the cone. The flat solar battery cell receives light only at the top surface and the reflection loss is not small. Therefore, it is difficult to sufficiently increase the incident light usage rate. Furthermore, this micromirror solar battery has the solar battery cells at the bottom of the case so as to prevent the solar battery cells from heating up due to light collection. 
     The U.S. Pat. No. 5,355,873 discloses a light collection type solar battery module having spherical solar battery cells. A thin metal sheet (common electrode) has multiple nearly semispherical recesses with reflecting inner surfaces. Legs are formed at the centers of the recesses for supporting solar battery cells. A conductive mesh supports multiple solar battery cells at their middle parts. The multiple solar battery cells are set in multiple recesses and electrically connected to the legs. The multiple solar battery cells are connected in parallel by the conductive mesh and sheet. The solar battery cells have no electrode at the top, bottom, or either end and, therefore, the electric current distribution is uneven within a solar battery cell. Hence, it is difficult to improve the electric power generation efficiency. Furthermore, all solar battery cells mounted on the sheet are connected in parallel, which is inconvenient for increasing the output voltage of the solar battery module. 
     The US Laid-Open Patent Publication No. 2002/0096206 discloses a solar battery module in which spherical solar battery cells are provided in the centers of multiple partially spherical recesses, respectively, the recesses each have a reflecting inner surface, multiple recesses are formed by two thin metal plates and an insulating layer between them, and the two thin metal plates are connected to the positive and negative electrodes of the spherical solar battery cell at the bottom part thereof to connect in parallel multiple solar battery cells. 
     In the above solar battery module, the spherical solar battery cells are electrically connected to the two thin metal plates at the bottom part. This causes a drawback that the distance between the upper half light receiving surface and the positive and negative electrodes of a spherical solar battery cell is large and the resistance loss upon output electric current retrieval is increased. Furthermore, all solar battery cells of the solar battery module are connected in parallel, which is inconvenient for increasing the output voltage of the solar battery module. 
     The inventor of the present application disclosed in the International Publication No. WO02/35612 a rod-shaped light receiving or emitting semiconductor element having a pair of electrodes on either end face and a solar battery module using the semiconductor element. However, when this rod-shaped semiconductor element has a higher length/diameter ratio, the resistance between the electrodes is increased. Therefore, the ratio is desirably set for approximately 1.5 or lower. 
     Patent Document 1: U.S. Pat. No. 4,136,436; 
     Patent Document 2: U.S. Pat. No. 6,204,545; 
     Patent Document 3: Japanese Laid-Open Patent Publication No. 2001-168369; 
     Patent Document 4: International Publication No. WO03/056633; 
     Patent Document 5: U.S. Pat. No. 5,482,568; 
     Patent Document 6: U.S. Pat. No. 5,355,873; and 
     Patent Document 7: US Laid-Open Patent Publication No. 2002/0096206. 
     DISCLOSURE OF THE INVENTION 
     Problems to be Solved by the Invention 
     As in the solar battery modules described in the above publications, when spherical or partially spherical, granular solar battery cells are used to constitute a solar battery module, the number of points to electrically connect the electrodes of the solar battery cells to the positive and negative electrode conductors of the module and the number of wire connections are increased, which is inconvenient for mass production. 
     When spherical solar battery cells are mounted in the centers of partially spherical recesses and light is collected by the reflecting surfaces of the recesses to illuminate the solar battery cells with the sunlight, there are spaces between the recesses, which is disadvantageous in increasing the usage rate of the incident sunlight. Furthermore, the ratio of the light receiving surface of the light collecting recesses to the light receiving surface of the solar battery cells in a plane view cannot be largely increased. Therefore, it is difficult to increase the output power in relation to the light input to the solar battery module surface. 
     For light collection by lenses in a solar battery module having granular solar battery cells, the same number of lenses circular in a plane views as the solar battery cells are required. This large number of lenses complicates the structure. 
     For using a light collection mechanism of the light reflecting type, a cooling mechanism for effectively cooling the solar battery cells is necessary because the solar battery cells significantly heat up. When the reflecting surface is partially spherical, it is difficult to create a smooth passage of the cooling fluid. In such a case, it is not easy to improve the cooling performance. 
     When multiple solar battery cells in a solar battery module are all connected in parallel, the output voltage of the solar battery module is equal to the output voltage of the solar battery cells. However, it is desirable that the output voltage of the solar battery module is changeable and, in the case of a light emitting panel in which multiple light emitting diodes are installed, the input voltage to the panel are changeable. 
     The object of the invention of the present application is to provide a panel-shaped semiconductor module using semiconductor elements having a larger light receiving area with no increase in the resistance between electrodes, to provide a panel-shaped semiconductor module having a smaller number of electrical connection points of semiconductor elements and wire connections, to provides a panel-shaped semiconductor module having a larger collecting power, to provides a panel-shaped semiconductor module advantageous for forming a lens part, and to provide a panel-shaped semiconductor module advantageous for improving the cooling performance. 
     Means to Solve the Problem 
     The panel-shaped semiconductor module relating to the present invention is a panel-shaped light receiving or emitting semiconductor module characterized by comprising multiple rod-shaped semiconductor elements each having light receiving or emitting capability and an axis and arranged in multiple rows and columns with their conducting direction aligned and their axes oriented in the row direction, a conductive connection mechanism electrically connecting in parallel multiple semiconductor elements in each row and electrically connecting in series multiple semiconductor elements in each column, and a conductive inner metal case housing the multiple semiconductor elements and constituting the conductive connection mechanism. 
     The multiple semiconductor elements each have a rod-shaped base consisting of a p-type or n-type semiconductor crystal, another conductive layer formed on a surface of the base except for a strap of area and having a conductivity type different from the base, a nearly cylindrical pn junction formed by the base and another conductive layer, and first and second electrodes formed on surfaces of the base on either side of the axis in a form of a strap parallel to the axis and ohmic-connected to the strap of area of the base and the other conductive layer, respectively. 
     The inner metal case comprises multiple reflecting surface-forming grooves each housing a row of multiple semiconductor elements and having a width decreasing from an opening to a bottom. The reflecting surface-forming grooves each comprises a light reflecting bottom plate and a pair of light reflecting oblique plates extending upward from either end of the bottom plate in an integrated manner. 
     The bottom plate has a mount protruding in a center portion in a width direction, on which a corresponding row of multiple semiconductor elements is placed and to which one of the first and second electrodes of the semiconductor elements is electrically connected. Multiple finger leads electrically connected to one of the oblique plates of each reflecting surface-forming groove and electrically connected to the other of the first and second electrodes of the corresponding row of multiple semiconductor elements are formed. A cutoff slit for cutting off the conductive part short-circuiting the first and second electrodes of a corresponding row of multiple semiconductor elements is formed in the bottom plate on one side of the mount over the entire length of the row. 
     ADVANTAGES OF THE INVENTION 
     The semiconductor element has a base, another conductive layer having a conductivity type different from that of the base, a pn junction, and first and second electrodes. The first and second electrodes are provided on the surfaces of the base on either side of the axis in the form of a strap parallel to the axis and ohmic-connected to the base and other conductive layer, respectively. Therefore, the distance between the first and second electrodes never exceeds the diameter of the base even if the ratio of the axial length to the diameter of the base is increased. Therefore, the ratio can be increased to a desired value. Then, the semiconductor element is increased in length so that the number of points to electrically connect multiple semiconductor elements can be decreased, simplifying the structure of the conductive connection mechanism. 
     The conductive connection mechanism connects in parallel multiple semiconductor elements in each row and connects in series multiple semiconductor elements in each column. When some semiconductor elements fail for some reason, the current flows through an alternative path bypassing the failed semiconductor elements, whereby all normal semiconductor elements continue to work. 
     The inner metal case comprises multiple reflecting surface-forming grooves having a width decreasing from the opening to the bottom. Each reflecting surface-forming groove comprises of a light reflecting bottom plate and a pair of light reflecting oblique plates. A corresponding row of multiple semiconductor elements is placed on a mount provided at the center portion of the bottom plate of the reflecting surface-forming groove. One of the first and second electrodes of the multiple semiconductor elements is electrically connected to the mount. 
     In this way, in the case of a light receiving semiconductor module, light collected by the reflecting surfaces of the reflecting surface-forming grooves can enter the semiconductor elements. The width at the opening of the reflecting surface-forming grooves can be three to four times larger or even much larger than the diameter of the semiconductor elements to increase the ratio of the reflecting surface-forming groove (light collection part) to the light receiving surface of the semiconductor elements, thereby increasing the light collecting magnification. In other words, a smaller number of semiconductor elements can effectively used to obtain high output power. 
     Furthermore, the semiconductor elements are placed on a mount protruding from the center portion of the bottom plate of the reflecting surface-forming groove. Light reflected by the bottom plate can enter the lower half of the semiconductor element. 
     Each row of multiple semiconductor elements is housed in each of multiple reflecting surface-forming grooves. Therefore, multiple cylindrical lenses corresponding to multiple reflecting surface-forming grooves, respectively, can advantageously used. The multiple reflecting surface-forming grooves formed by the inner metal case each comprises a bottom plate and a pair of oblique plates. The inner metal case can be constituted by a sheet of metal plate, reducing the number of parts and simplifying the structure. 
     The present invention can have the following various structures as dependent claims. 
     (1) The finger leads are each formed by bending a lower end of a score cut part formed on an upper half of an oblique plate nearly at right angle. 
     (2) The cutoff slits of the inner metal case are each formed by punching out multiple tie bars to form a continuous cutoff slit after one of the first and second electrodes of each row of multiple semiconductor elements is connected to the mount and the other of the first and second electrodes is connected to the finger lead. 
     (3) An outer metal case fitted on an underside of the inner metal case and having a cross section nearly similar to that of the inner metal case and an electrically insulating synthetic resin layer interposed between the inner and outer metal cases are provided and the inner and outer metal cases are bonded and integrated via the electrically insulating synthetic resin layer. 
     (4) In the above (3), extensions each extending beyond either end of the inner metal case by a predetermined length in the row direction are provided at either end of the outer metal case in the row direction and side plug blocks made of an insulating material are fitted in and fixed to case housing grooves formed in the extensions. 
     (5) In the above (4), the reflecting surface-forming grooves of the inner metal case are filled with a transparent flexible insulating synthetic resin material to embed the semiconductor elements and finger leads therein. 
     (6) In the above (4), a glass or synthetic resin cover member fixed to the inner metal case and side plug blocks for covering a top of the inner metal case is provided. 
     (7) In the above (6), the cover member has multiple cylindrical lens parts corresponding to multiple rows of semiconductor elements, respectively. 
     (8) A duct member forming a passage for a cooling fluid is provided on an outer surface of the outer metal case. 
     (9) An antireflection coating is formed on surfaces of the semiconductor elements except for the areas where the first and second electrodes are provided. 
     (10) The base of the semiconductor elements is made of a p-type Si monocrystal or Si polycrystal, the other conductive layer is formed by diffusing P, Sb, or As as an n-type impurity, and the semiconductor elements are solar battery cells. 
     (11) The base of the semiconductor elements is made of an n-type Si monocrystal or Si polycrystal, the other conductive layer is formed by diffusing B, Ga, or Al as a p-type impurity, and the semiconductor elements are solar battery cells. 
     (12) The semiconductor elements are light emitting diode elements having light emitting capability. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a solar battery module relating to Embodiment 1. 
         FIG. 2  is a cross-sectional view at the line II-II in  FIG. 1 . 
         FIG. 3  is a cross-sectional view at the line III-III in  FIG. 1 . 
         FIG. 4  is a plane view of the solar battery module with a cover member removed. 
         FIG. 5  is an enlarged view of the core part of  FIG. 4 . 
         FIG. 6  is a perspective view of the side plug block. 
         FIG. 7  is a perspective view of the core part of the reflecting surface-forming groove of the inner metal case. 
         FIG. 8  is an enlarged cross-sectional view of the semiconductor element. 
         FIG. 9  is a cross-sectional view at the line IX-IX in  FIG. 8 . 
         FIG. 10  is an enlarged perspective view of the semiconductor element. 
         FIG. 11  is a circuit diagram equivalent to the conductive connection mechanism. 
         FIG. 12  is a perspective view equivalent to  FIG. 7  of a modified embodiment. 
         FIG. 13  is a cross-sectional view equivalent to  FIG. 2  of a solar battery module relating to Embodiment 2. 
         FIG. 14  is an enlarged cross-sectional view of a light emitting semiconductor element relating to Embodiment 3. 
         FIG. 15  is a cross-sectional view at the line XIV-XIV in  FIG. 13 . 
     
    
    
     DESCRIPTION OF NUMERALS 
     
         
         
           
             M, Ma solar battery module (panel-shaped semiconductor module) 
               1  semiconductor element 
               2  conductive connection mechanism 
               3  inner metal case 
               4  outer metal case 
               4 A extension 
               5  cover member 
               5   a  cylindrical lens part 
               6  insulating synthetic resin material 
               7  synthetic resin layer 
               8  side plug block 
               11  base 
               12  diffusion layer 
               13  pn junction 
               14  positive electrode 
               15  negative electrode 
               16  antireflection coating 
               20  reflecting surface-forming groove 
               21  bottom plate 
               21   a  mount 
               22 ,  23  oblique plate 
               25 ,  25 A finger lead 
               26  cutoff slit 
               35  duct member 
               40  light emitting semiconductor element (light emitting diode element) 
               41  base 
               42  diffusion layer 
               43  pn junction 
               44  positive electrode 
               45  negative junction 
               46  antireflection coating 
           
         
       
    
     BEST MODE FOR IMPLEMENTING THE INVENTION 
     The panel-shaped semiconductor module of the present invention basically comprises multiple rod-shaped light receiving or emitting semiconductor elements arranged in multiple rows and columns, a conductive connection mechanism connecting in parallel multiple semiconductor elements in each row and connecting in series multiple semiconductor elements in each column, and an inner metal case housing the multiple semiconductor elements and constituting the conductive connection mechanism, wherein the inner metal case has multiple reflecting surface-forming grooves housing multiple rows of semiconductor elements, respectively, and having a width decreasing from the opening to the bottom. 
     Embodiment 1 
     The panel-shaped semiconductor module relating to Embodiment 1 is a solar battery module (solar battery panel) receiving the sunlight and generating electric power. This solar battery module M will be described with reference to the drawings. As illustrated in  FIGS. 1 to 5 , the solar battery module M comprises multiple semiconductor elements  1  having light receiving capability, a conductive connection mechanism  2  electrically connecting the semiconductor elements  1  (see  FIG. 11 ), an inner metal case  3  housing the multiple semiconductor elements  1 , an outer metal case  4  fitted on the underside of the inner metal case  3 , a transparent cover member  5  covering the top of the inner metal case  3 , a silicone rubber insulating synthetic resin material  6  introduced in the inner metal case  3 , a synthetic resin layer  7  bonding the inner and outer metal cases  3  and  4  together, multiple side plug blocks  8 , and two reinforcement plates  9 . 
     As illustrated in  FIGS. 8 to 10 , the semiconductor element  1  is a rod-shaped solar battery cell having an axis  1   a  and a nearly circular (a partial circle close to a circle) cross section. The semiconductor element  1  has a p-type silicon monocrystal rod-shaped base  11 , an n-type diffusion layer  12  (which corresponds to another conductive layer having a conductivity type different from that of the base  11 ), a pn junction  13 , positive and negative electrodes  14  and  15 , and an antireflection coating  16 . The semiconductor element  1  receives the sunlight and generates photovoltaic power of approximately 0.5 to 0.6 V. 
     The base  11  is a p-type silicon monocrystal column having a diameter of approximately 1.8 mm and a length of approximately 5 mm with a flat bottom section  11   a  in the form of a strap (for example having a width of approximately 0.6 mm) parallel to the axis  1   a  of the column (see  FIG. 9 ). The diffusion layer  12  is an n-type conductive layer formed by thermal-diffusing P (phosphorus) in the surface part of the base  11  to a depth of 0.5 to 1.0 μm except for a strap of area including the flat section  11   a  and its vicinity at either end thereof. 
     The p-type base  11  and n-type diffusion layer  12  together form a nearly cylindrical (a partial cylinder close to a cylinder) pn junction  13 . The pn junction  13  surrounds most of the periphery of the semiconductor element  1  around the axis  1   a . A strap of positive electrode  14  having a width of approximately 0.4 mm is provided on the flat section  11   a  of the base  11 . A strap of negative electrode  15  having a width of approximately 0.4 mm is provided on the surface of the base  11  at a position across the axis  1   a  from the positive electrode  14 . The positive electrode  14  is formed by firing a paste of silver mixed with aluminum. The negative electrode  15  is formed by firing a paste of silver mixed with a small amount of antimony. The positive and negative electrodes  14  and  15  are provided on the surface of the base  11  on either side of the axis  1   a  in the form of a strap parallel to the axis  1   a . The positive electrode  14  is ohmic-connected to the base  11  and the negative electrode  15  is ohmic-connected to the diffusion layer  12 . 
     An antireflection coating  16  consisting of a silicon oxide coating or silicon nitride coating is formed on the surface of the semiconductor element except for the areas where the positive and negative electrodes  14  and  15  are provided for the purpose of antireflection and silicon surface passivation. When the semiconductor element  1  is illuminated with the sunlight bm and the silicon monocrystal of the base  11  absorbs the sunlight, carriers (electrons and holes) are generated, the pn junction  13  separates the electrons from the holes, and photovoltaic power is generated between the positive and negative electrodes  14  and  15 . Even if the incident direction of the sunlight entering in directions perpendicular to the axis  1   a  changes, the semiconductor element  1  has uniform light reception sensitivity and efficiently receives the sunlight bm in a wide range of directions and generates electric power. 
     As illustrated in  FIG. 10 , the positive and negative electrodes  14  and  15  are positioned nearly symmetrically about the axis  1   a  of the base  11 . For carriers generated in the base  11  upon receiving the sunlight bm, the sum of the distances from any circumferentially different point, for example A, B, or C, to the positive and negative electrodes  14  and  15  is nearly equal in any plane perpendicular to the axis  1   a  of the base  11 , namely (a+b)≈(a′+b′)≈(a″+b″). The photoelectric current distribution is uniform with regard to the axis  1   a  of the base  11  and resistance loss due to uneven distribution can be reduced. 
     As illustrated in  FIGS. 2 ,  4 ,  5 , and  7 , multiple semiconductor elements  1  are arranged in multiple rows and columns in multiple reflecting surface-forming grooves  20  of the inner metal case  3  with their conducting direction aligned and their axes  1   a  oriented in the row direction. Multiple semiconductor elements  1  are arranged with their positive electrode  14  at the bottom and their negative electrode  15  at the top, whereby they have a vertically downward conducting direction. 
     The inner metal case  3  is formed by punching a thin plate of iron/nickel alloy (Ni 42% and Fe 58%) into a monolithic item in a press machine with a specifically-shaped die. The light receiving inner surface of the inner metal case  3  is mirror finished or either gold or silver plated for improved light reflecting performance. 
     As illustrated in  FIGS. 2 ,  4 ,  5 , and  7 , the inner metal case  3  comprises the same number of gutter-like reflecting surface-forming grooves  20  as the rows of semiconductor elements  1 , and flanges  3   f  and coupling terminals  3   a  at the right and left ends. The reflecting surface-forming grooves  20  have an inverted trapezoidal cross section having a width linearly decreasing from the opening to the bottom. Each reflecting surface-forming groove  20  comprises a bottom plate  21  and a pair of oblique plates  22  and  23  extending upward from either end of the bottom plate  21 . The top ends of the oblique plates  22  and  23  of adjacent reflecting surface-forming grooves  20  are coupled by a narrow coupling plate  24 . 
     Each bottom plate  21  has a mount  21   a  having a trapezoidal cross section and protruding upward at the center portion in the width direction. A corresponding row of multiple semiconductors  1  is placed on the mount  21   a  and their positive electrodes  14  are bonded to the mount  21   a  using a conductive epoxy resin for electrical connection. Multiple finger leads  25  integrally extend from the middle part of the right oblique plate  23  of each reflecting surface-forming groove  20  to be electrically connected to the negative electrodes  15  of the corresponding row of multiple semiconductor elements  1 , respectively. The negative electrodes  15  of the semiconductor elements  1  are bonded to the finger leads  25  using a conductive epoxy resin for electric connection. The finger leads  25  are each formed by bending the lower end of a score cut part formed on the upper half of the right oblique plate  23  at right angle (see  FIG. 7 ). 
     As illustrated in  FIG. 2 , a cutoff slit  26  is formed in each bottom plate  21  on the right side of the mount  21   a  over the entire length in the row direction (the entire length of the inner metal case  3 ) for cutting off the conduction from the multiple positive electrodes  14  of the corresponding row of multiple semiconductor elements  1  to the multiple finger leads  25  so as to cut off the conductive part short-circuiting between the positive and negative electrodes  14  and  15  of the corresponding row of multiple semiconductor elements  1 . 
     Each cutoff slit  26  is formed by punching out the tie bars (not illustrated) of multiple tie bar punch-out portions  26   a  to form a continuous cutoff slit  26  after the positive electrodes  14  of each row of multiple semiconductors  1  are bonded to the mount  21   a  and the negative electrodes  15  are bonded to the finger leads  25 . 
     As described above, after multiple semiconductor elements  1  are arranged in multiple rows and columns in the inner metal case  3  with their positive electrodes  14  connected to the mount  21   a  and their negative electrodes  15  connected to the finger leads  25  and the cutoff slit  26  is formed in the bottom plate  21  of each reflecting surface-forming groove  20 , the semiconductor elements  1  in each row are connected in parallel by the inner metal case  3  and multiple finger leads  25  and multiple semiconductor elements in each column are connected in series by the inner metal case  3  and multiple finger leads  25 . In this way, the inner metal case  3  including multiple finger leads  25  constitutes a conductive connection mechanism  2  electrically connecting in series multiple semiconductor elements  1  in each column and electrically connecting in parallel multiple semiconductor elements  1  in each row (see  FIG. 11 ). 
     As illustrated in  FIGS. 2 to 5  and  7 , an outer metal case  4  having a cross section nearly similar to the inner metal case  3  is fitted on the underside of the inner metal case  3 . The outer metal case  4  is formed by forming the same iron/nickel alloy plate (for example having a thickness of 0.4 mm) as the inner metal case  3 . The outer metal case  4  has flanges  4   f  at either end in the column direction. The outer metal case  4  has at either end in the row direction extensions  4 A extending beyond either end of the inner metal case  3  in the row direction by a predetermined length. The inner and outer metal cases  3  and  4  are bonded and integrated together via an electrically insulating synthetic resin layer  7  (having a thickness of 0.1 to 0.5 mm) consisting of a heat-resistant insulating adhesive such as polyimide resin introduced between them. 
     As illustrated in  FIGS. 3 and 5  to  7 , side plug blocks  8  made of an insulating material (for example a ceramic or glass material) are fitted in case housing grooves  27  formed in the extensions  4 A of the outer metal case  4  and bonded thereto using a heat-resistant insulating synthetic resin adhesive such as polyimide resin for completely sealing the ends of the inner metal case  3  in the row direction. The side plug blocks  8  have an oblique inner surface  8   a  tilted similarly to the oblique plates  22  and  23  for improved light reception. 
     As illustrated in  FIG. 2 , a flexible transparent silicone rubber insulating synthetic resin material  6  is introduced into the reflecting surface-forming grooves  20  of the inner metal case  3  so as to embed the semiconductor elements  1  and finger leads  25 , degassed under reduced pressure, and cured. 
     As illustrated in  FIGS. 1 ,  2 , and  3 , a transparent glass or synthetic resin cover member  5  covering the top of the inner metal case  3  and fixed to the inner metal case  3  and side plug blocks  8  is provided. The cover member  5  is desirably made of white reinforced glass or borosilicate glass. The cover member  5  has multiple cylindrical lens parts  5   a  corresponding to multiple rows of semiconductor elements  1 , respectively, at the upper part and engaging parts  5   b  fitted in the upper parts of multiple reflecting surface-forming grooves  20  at the lower part. The cover member  5  has flat parts  5   c  at right and left ends in  FIGS. 1 and 2 . 
     In order to fix the cover member  5  to the inner metal case  3 , the cover member  5  is attached to the inner metal case  3  with a thick layer of silicone resin applied on the entire underside surface of the cover member  5 , whereby the cover member  5  is bonded to the silicone rubber  6  (insulating synthetic resin material) and oblique plates  22  and  23  of multiple reflecting surface-forming grooves  20 , to other top surface portions of the inner metal case  3 , and to the inner sides of multiple side plug blocks  8 . Then, the entire structure is heated under reduced pressure to cure the silicone resin adhesive/sealing material  29 . Here, the inner space of each reflecting surface-forming groove  20  is completely filled with the silicone rubber  6  and adhesive/sealing material  29 . The right and left flat parts  5   c  of the cover member  5  and flanges  3   f  and  4   f  are fastened together by multiple metal or synthetic resin bolts  30 . Here, the bolts  30  are insulated from the flanges  3   f.    
     As illustrated in  FIGS. 1 and 3 , a polyimide resin reinforcement plate  9  closing the top of multiple side plug blocks  8  is provided and fixed using the same adhesive/sealing material as the above described adhesive/sealing material  29  for reinforcing the integrity of the multiple side plug blocks  8  and inner metal case  3 . 
     As illustrated in  FIGS. 1 to 5 , coupling terminal plates  3   a  are exposed at right and left ends of the inner metal case  3  and extend over the entire length in the row direction for electrically connecting multiple solar battery modules M or coupling the output retrieval lines. Each coupling terminal plate  3   a  has multiple bolt holes  31 . 
       FIG. 11  shows an equivalent circuit to multiple semiconductor elements  1  and the conductive connection mechanism  2  of the above described solar battery module M. The semiconductor elements  1  are presented by diodes  1 A. In this equivalent circuit, multiple diodes  1 A in each row are connected in parallel and multiple diodes  1 A in each column are connected in series, whereby all diodes are serial/parallel-connected in a mesh circuit. Photovoltaic power is generated between the positive and negative electrode terminals  18  and  19 . 
     Function and advantages of the above described solar battery module M will be described hereafter. 
     The rod-shaped semiconductor elements  1  of this solar battery module M are nearly symmetric about their axes and can receive the sunlight in any direction (directions over approximately 270 degrees), exhibiting sensitivity for a wide angle of light reception. The inner metal case  3  has multiple reflecting surface-forming grooves  20  having a width linearly decreasing from the opening to the bottom. A row of multiple semiconductors  1  is placed at the bottom of each reflecting surface-forming groove  20 . The reflecting surface-forming groove  20  has a light reflecting inner surface. Hence, the sunlight falls on the semiconductor elements  1  after multiple reflections on the inner surface of the reflecting surface-forming grove  20 . 
     The width at the opening of the reflecting surface-forming groove  20  can be 3 to 15 times larger than the diameter of the semiconductor elements  1  so that the horizontal area ratio of the reflecting surface-forming groove  20  (light collection part) to the projected light receiving cross section of the semiconductor elements  1  in each row is increased for larger collecting power. Therefore, the necessary number or light receiving area of semiconductor elements  1  can be reduced, which is advantageous for silicon cost and production cost. Furthermore, the semiconductor elements  1  are fixed on the mount  21   a  of the bottom plate  21  of the reflecting surface-forming groove  20 . Light reflected by the bottom plate and scattered light can easily enter the semiconductor elements  1 , the semiconductor elements  1  have a larger light receiving range. Additionally, the semiconductor elements  1  can easily be positioned and fixed using a conductive epoxy resin. 
     The transparent flexible silicone rubber  6  is used to embed the semiconductor elements  1  in the reflecting surface-forming groove  20 . The semiconductor elements  1  are completely protected from external impact or moisture or air. The silicone rubber  6  absorbs expansion or shrinkage of the solar battery module M due to temperature changes. The refractive index of the silicone rubber  6  is close to that of the cover member  5  and antireflection coating  16 , which reduces reflection loss at the interface. Furthermore, the silicone rubber  6  optically couples the semiconductor elements  1 , which makes it easier for not only collected direct light but also scattered light resulting from multiple internal reflections to enter the semiconductor elements  1 . 
     In addition, the cover member  5  has cylindrical lens parts  5  each corresponding to a reflecting surface-forming groove  20 . The sunlight energy intensity can be approximately 5 to 15 times increased through the light collection by the cylindrical lens parts  5   a . The output power of the semiconductor elements  1  can be approximately 7 to 15 times increased through the light collection by the cylindrical lens parts  5   a  and light collection by the reflecting surface-forming grooves  20  compared with the case of no light collection by them. 
     The conductive connection mechanism  2  connects in parallel multiple semiconductor elements  1  in each row and connects in series multiple semiconductor elements  1  in each column. When some semiconductor elements  1  fail for some reason (disconnection, poor connection, in shade, etc.), the current flows through an alternative path bypassing the failed semiconductor elements, whereby all normal semiconductor elements  1  continue to work. 
     The semiconductor elements  1  have a nearly columnar rod-shape. The positive and negative electrodes  14  and  15  are provided on the surface on either side of the axis in the form of a strap parallel to the axis and ohmic-connected to the base  11  or to the diffusion layer  12 . Therefore, no matter how much the axial length/diameter ratio of the base  11  is increased, the distance between the positive and negative electrodes  14  and  15  is smaller than the diameter of the base  11  and the electric resistance between the positive and negative electrodes  14  and  15  can be maintained small. The semiconductor elements  1  can be increased in length to reduce the number of electric connections of multiple semiconductor elements  1 , thereby simplifying the structure of the conductive connection mechanism  2 . 
     The solar battery module M easily heats up and, when heating up, its power generation efficiency is lowered. The inner and outer metal cases  3  and  4  are made of a thin metal plate and integrated together. The inner metal case  3  has multiple gutter-like reflecting surface-forming grooves  20 , of which the inner surfaces serve as a reflector/light collector and the back sides serve as a radiator. Particularly, the reflecting surface-forming grooves  20  have a W-shaped cross section with the upwardly bulging mount  21   a  of the bottom plate  21 , improving rigidity and strength and increasing the heat dissipation area. Thermal energy absorbed by the solar battery module M is transmitted through the inner metal case  3 , polyimide synthetic resin thin layer  7 , and outer metal case  4  and released outside. 
     The reflecting surface-forming grooves  20  of the inner metal case  3  serve both as a container to receive the silicone rubber  6  and as a reception part for engaging with and positioning the engaging part  5   b  of the cover member  5 . 
     The finger leads  25  corresponding to the respective semiconductor elements  1  are integrally formed on one oblique plate  23  of a reflecting surface-forming groove  20 . The finger leads  25  are bonded to the negative electrodes  1  of the semiconductors  1  using a conductive epoxy resin. In this way, separate connection leads can be eliminated. 
     The finger leads  25  can be produced as score cut parts formed on the oblique plate  23  while the inner metal case  3  is produced. Upon assembly, the positive electrodes  14  of each row of multiple semiconductors  1  are bonded to the mount  21   a  using a conductive epoxy resin and then the score cut parts are bent to form the finger leads  25 , which are then bonded to the negative electrodes  15  of the semiconductor elements  1  using a conductive epoxy resin. After all finger leads  25  are bonded to the negative electrodes of the semiconductor elements  1  in the solar battery module M, the tie bars (not illustrated) connecting multiple tie bar punch-out portions  26   a  are punched out. The finger leads  25  also serve as a marking for positions where the semiconductor elements  1  are placed. The multiple tie bars serve to maintain the integrity of the inner metal case  3  while the inner metal case  3  is formed and allow the inner metal case  3  to be formed from a sheet of metal plate, reducing the number of parts and simplifying the structure. 
     Partial modifications of the above described embodiment will be described hereafter. 
     1) As illustrated in  FIG. 12 , in place of the finger leads  25 , connection pieces  50  formed separately from the inner metal case  3  by punching out a conductive metal, such as iron and nickel, thin plate are provided at positions corresponding to the semiconductor elements  1  and finger leads  25 A horizontally extending to the left are formed at the lower end of the connection pieces  50 . 
     The connection piece  50  is obtained by integral-forming a coupling section  50   a  to be bonded to the coupling part  24  of the inner metal case  3 , oblique sections  50   b  and  50   c  provided on either side of the coupling section  50   a  to be bonded to the oblique plates  22  and  23 , and the finger lead  25 A. For example, the connection piece  50  is bonded to the coupling part  24  and oblique plates  22  and  23  on the either side thereof using a conductive epoxy resin and the leading end of the finger lead  25 A is bonded to the negative electrode  15  of the corresponding semiconductor element  1  using a conductive epoxy resin for electric connection. Here, the coupling section  50   a  and oblique sections  50   b  and  50   b  have a width of for example 2 to 3 mm and the finger lead  25 A has a width of for example 0.5 to 1 mm. 
     2) The above described solar battery module M has nine reflecting surface-forming grooves  20 . However, several tens of rows and several tens of columns can be provided. The materials of the inner metal case  3 , positive and negative electrodes  14  and  15 , and outer metal case  4  and various synthetic resin materials are not restricted to the above described embodiment and can be changed by a person of ordinary skill in the field as appropriate. 
     The diameter of the base  11  of the semiconductor elements  1  is not restricted to the above described embodiment and can be approximately 1.0 to 2.5 mm. The axial length of the semiconductor elements  1  is not restricted to the above described embodiment and can be any length not smaller than 5.0 mm. The semiconductor elements  1  can have a length extending over the entire row. In such a case, it is desirable that multiple finger leads  25  are provided at proper intervals in the row direction. 
     3) The base  11  of the semiconductor elements  1  can be a p-type silicon polycrystal and the n-type impurity forming the diffusion layer  12  can be Sb or As. Alternatively, the semiconductor elements  1  can comprise an n-type silicon monocrystal or polycrystal base  11  and a diffusion layer  12  having a p-type impurity such as B, Ga, and Al. The pn junction  13  is not necessarily created by the diffusion layer  12 . The pn junction  13  can be created by forming a film on the surface of the base  11  or injecting ions in the surface of the base  11  to form another conductive layer having a conductivity type different from that of the base  11 . 
     4) The flat section  11   a  of the base  11  of the semiconductor elements  1  can be omitted. The base  11  can be in the form of a rod having a circular cross section and the positive electrode has the same form as the negative electrode  15 . In such a case, the positive and negative electrodes can be made of metal materials of different colors so that they can be distinguishable from each other. 
     5) The cross section of the reflecting surface-forming grooves  20  of the inner metal case  3  is not particularly restricted to the above described embodiment. Any groove having a width linearly or nonlinearly decreasing from the opening to the bottom for light collection capability can be used. The inner metal case  3  of a solar module M can be constituted by multiple molded metal plates. 
     Embodiment 2 
     As illustrated in  FIG. 13 , a solar battery module Ma (panel-shaped semiconductor module) has a duct member  35  fitted on the underside of the above described solar battery M. The solar battery module Ma has the same structure as the solar battery module M except for the duct member  35 . Therefore, the same components are designated by the same reference numerals and their explanation will be omitted. The duct member  35  has an inverted trapezoidal body  35   a  forming a coolant passage  36  together with the outer metal case  4  for a forced or natural flow of a coolant fluid such as air and cooling water, and flanges  35   f  extending from right and left ends of the body  35   a . The flanges  35   f  are each fastened to the flat plate  5  of the cover member  5 , flange  3   f  of the inner metal case  3 , and flange  4   f  of the outer metal case  4  by multiple bolts  30  from below. 
     With a coolant such as air and cooling water running through the coolant passage  36 , the inner and outer metal cases  3  and  4  and semiconductor elements  1  can effectively be cooled. Particularly, the inner and outer metal cases  3  and  4  have intricate outer surfaces and accordingly have a large heat transfer area. The semiconductor elements  1  are close to the coolant. Therefore, a high cooling performance can be obtained. 
     Embodiment 3 
     This embodiment relates to light emitting semiconductor elements (light emitting diodes) applied to a high output power light emitting diode module with a reflecting mechanism, which is a panel-shaped semiconductor module. This high output power light emitting diode module with a reflecting mechanism comprises light emitting semiconductor elements in place of the semiconductor elements  1  of the above described solar battery module M. 
     The light emitting semiconductor element will be described hereafter. 
     As illustrated in  FIGS. 14 and 15 , a light emitting semiconductor element  40  has a rod-shaped base  41  consisting of an n-type semiconductor crystal, a p-type diffusion layer  42  formed in the surface part of the base  41  (which corresponds to another conductive layer having a conductivity type different from the base), a nearly cylindrical pn junction  43  formed by the base  41  and diffusion layer  42 , positive and negative electrodes  44  and  45 , and an antireflection coating  46 . 
     The base  41  consists of an n-type GaAs crystal having a diameter of 1.0 mm and a length of 5 mm with a flat bottom section  41   b  in the form of a strap (having a width of approximately 0.2 to 0.3 mm) parallel to the axis  41   a . The diffusion layer  42  is formed by thermal diffusing a p-type impurity Zn (zinc) in the surface part of the base  41  to a depth of 0.5 to 1.0 μm except for a strip of area consisting of the flat section  41   b  and its vicinity at either end thereof in the circumferential direction. The positive and negative electrodes  44  and  45  are made of silver-based materials. The negative electrode  44  is provided on the flat section  41   b  at the center in the width direction in the form of a strap extending over the entire length and ohmic-connected to the base  41 . The positive electrode  44  is provided on the surface of the diffusion layer  42  at a position across the axis  41   a  of the base  41  from the negative electrode  45  and ohmic-connected to the diffusion layer  42 . 
     An antireflection coating  46  consisting of a thin silicon oxide coating or silicon nitride coating and having passivation function is formed on the surface of the base  41  and diffusion layer  42  except for the areas where the positive and negative electrodes  44  and  45  are formed. The light emitting semiconductor element  40  emits infrared light from near the pn junction  43  when a forward current runs from the positive electrode  44  to the negative electrode  45 . Because the pn junction  43  has a partial cylindrical form close to a cylinder, the generated infrared light crosses the surface of the semiconductor element  40  at right angle and exits outside. Therefore, internal reflection loss of the light is reduced and light emission efficiency is improved compared with the prior art light emitting diode having a flat pn junction. 
     In the high output power light emitting diode module with a reflecting mechanism in which the light emitting semiconductor elements  40  are installed in place of the semiconductor elements  1  of the above described embodiment, when a forward current is supplied from the positive terminal to the negative terminal, the forward current runs through all light emitting semiconductor elements  40 , leading to emission of infrared light. The infrared light emitted from the light emitting semiconductor elements  40  exits outside through the cylindrical lens parts  5   a  of the cover member  5  directly from the reflecting surface-forming groove  20  or after reflected on the reflecting surfaces. 
     The light emitting semiconductor elements  40  increase their light output as the forward current is increased. However, conversion loss leads to heat generation and to rise in temperature, which reduces light emission efficiency. This light emitting diode module is excellent in heat dissipation as the above described solar battery module M and therefore reduces the rise in the module temperature. Hence, a large light output can be obtained by supplying a large current to a smaller number of light emitting semiconductor elements  40 , reducing the light emitting diode module production cost. 
     The light emitting diode module can be a useful industrial infrared generation apparatus such as a light source of medical equipment, various infrared sensors, and infrared lighting. 
     Partial modifications of the above described light emitting diode module and light emitting semiconductor element  40  will be described hereafter. 
     1) The light emitting diode module also can have a duct member as the above described solar battery module Ma. 
     2) Various light emitting diodes are produced using various semiconductor materials and emit light of various light emission wavelengths according to the characteristics of the semiconductor material. Any light emitting diode produced using such various semiconductor materials can be used. Other than infrared light, light emitting diodes emitting visible or ultraviolet light may also be used. 
     The base can be constituted by a semiconductor crystal for example selected from GaAlAs, GaP, InGaP, GaN, GaInN, and SiC. SiC is a hexagonal crystal and yields a hexagonal column mono crystal. Such a hexagonal column mono crystal can be used to constitute the base. 
     The pn junction of the light emitting semiconductor element is not necessarily created by a diffusion layer. The pn junction can also be created by forming a film on the surface of the base or injecting ions in the surface of the base to create another conductive layer having a conductivity type different from that of the base. 
     INDUSTRIAL APPLICABILITY 
     The solar battery module is applicable to various fields as a solar power generation apparatus. The light emitting module is applicable to various fields according to the type of light generated.