Abstract:
The purpose of the present invention is to provide a double-sided light emitting type semiconductor light emitting device that can be easily fabricated even if a semiconductor light emitting element is flip-chip mounted, and to provide a fabrication process for the same. The semiconductor light emitting device has a plurality of lead frames, a plurality of semiconductor light emitting elements connected to the plurality of lead frames, and a covering member that covers the plurality of semiconductor light emitting elements. The semiconductor light emitting device is characterized in that the edge of one lead frame among the plurality of lead frames is disposed in close proximity to the edge of another lead frame so as to form a gap, and the plurality of semiconductor light emitting elements are flip-chip mounted on the front surface and rear surface of the one lead frame and the other lead frame so as to straddle the gap.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a double-sided semiconductor light emitting device fabricated by flip-chip mounting semiconductor light emitting elements on both sides of a leadframe, and a method for fabricating the same. 
       BACKGROUND 
       [0002]    Semiconductor light emitting devices (hereinafter called LED devices unless specifically designated otherwise), fabricated by mounting semiconductor light emitting elements diced from a wafer (hereinafter called LED dies unless specifically designated otherwise) on a leadframe or circuit substrate and packaged by covering them with a material such as a resin or glass, are widely used in various applications. While such LED devices can take various configurations according to the application, LED dies may be mounted on both sides of a leadframe or circuit substrate in order to increase the amount of light emission by enlarging the spreading angle of the LED device while compensating for the strong directional characteristics that the LED dies exhibit. 
         [0003]    LED devices with LED dies mounted on both sides of a leadframe have been known for a long time (for example, refer to patent document 1).  FIG. 25  is a diagram corresponding to FIG. 2 in patent document 1. For convenience, some of the reference numerals used to designate the component elements have been changed. 
         [0004]    In  FIG. 25 , two light emitting elements (LED dies)  421  are mounted on the left and right sides of a forward end portion of a leadframe  422   a.  Each light emitting element  421  is electrically connected to a leadframe  422   b  by a wire. The leadframes  422   a  and  422   b  are, respectively, a common positive terminal and a common negative terminal. The light emitting elements  421  are sealed with an epoxy resin  423 , and light collecting portions  404  are formed on the left and right sides of the epoxy resin  423 . The semiconductor light emitting device shown in  FIG. 25  has directional characteristics shown as  404   a  and  404   b  in the figure. 
         [0005]    When each LED die is connected by a wire, the light emitting efficiency of the LED device decreases because of the shadow of the wire. Furthermore, the size of the LED device increases because there is a need to provide an area for routing the wires. To address this, each LED die having an anode and cathode only on one face thereof (hereinafter called the bottom face) may be connected directly to a leadframe or to electrodes on a circuit substrate (hereinafter called flip-chip mounting). It is known that flip-chip mounting contributes to enhancing the light emitting efficiency and reducing the mounting area. The major reason is that the anode and cathode of the LED die are bonded directly to the leadframe or to the electrodes on the circuit substrate, eliminating the need for the wire. 
         [0006]    An LED device with LED dies flip-chip mounted on both sides of a circuit substrate as described above is known in the art (for example, refer to patent document 2).  FIG. 26  is a diagram corresponding to FIG. 2 in patent document 2. For convenience, some of the reference numerals used to designate the component elements have been changed. 
         [0007]    In  FIG. 26 , reflective cups  505  for accommodating LED chips  504   c  are formed substantially centered in the circuit substrate  502  and symmetrically between the upper and lower surface thereof. Each reflective cup  505  includes a bottom face  505   a  and a sloping face  505   b,  and electrode patterns  507   a  and  507   b  formed on the upper or lower surface of the circuit substrate  502  are disposed opposite each other across a gap formed in the bottom face  505   a  of the reflective cup  505 . The LED chip  504   c  is flip-chip mounted on the bottom face  505   a  of the reflective cup  505  in such a manner as to straddle the gap between the electrode patterns  507   a  and  507   b.  The reflective cup  505  is filled with an optically transmissive resin  508 . 
         [0008]    Another possible method for increasing the brightness of the LED device is by increasing the number of LED dies. For example, it is known in the art to mount four or more LED dies on both sides of the circuit substrate (for example, refer to FIG. 1 in patent document 3).  FIG. 27  is a diagram corresponding to FIG. 1 in patent document 3. For convenience, some of the reference numerals used to designate the component elements are changed. 
         [0009]      FIG. 27  is a cross-sectional view of a light source device (LED device)  605 A having a light emitting element (LED die) mounting enamel substrate  601   a.  In the light source device  605 A, light emitting elements  606  are mounted in reflective recessed portions  604   d  formed in both surfaces J and K of the light emitting element mounting enamel substrate  601   a,  and the reflective recessed portions  604   d  are each filled with a transparent resin  609  to seal the light emitting element  606  therein. The light emitting element mounting enamel substrate  601   a  is formed by covering a core metal  602   a  with an enamel layer  603 , and a total of six reflective recessed portions  604   d  for accommodating the respective light emitting elements  606  are formed in both surfaces J and K. An electrode  607   c  for feeding the light emitting elements  606  is formed on top of the enamel layer  603 . A portion of the electrode  607   c  is formed so as to extend into the bottom face of each reflective recessed portion  604   d,  and the light emitting element  606  is mounted thereon by die bonding or wire bonding. 
       PRIOR ART DOCUMENTS 
     Patent Documents 
       [0010]    Patent document 1: Japanese Utility Model Publication No. S56-149477 (FIG. 2) 
         [0011]    Patent document 2: Japanese Unexamined Patent Publication No. 2003-229603 (FIG. 2) 
         [0012]    Patent document 3: Japanese Unexamined Patent Publication No. 2006-310584 (FIG. 1) 
       SUMMARY 
       [0013]    In the case of the LED device (semiconductor light emitting device) shown in  FIG. 25 , the light emitting efficiency is low compared with the flip-chip mounting type, because of the use of wires as earlier described. 
         [0014]    The LED device shown in  FIG. 26  employs flip-chip mounting, but is not easy to fabricate because the LED dies (LED chips  504   c ) are flip-chip mounted in the recessed portions of the circuit substrate  502 . Since a detailed description of the LED die mounting process is not given in patent document 2, the details of the mounting process is not known. In one possible fabrication method, for example, each individual LED die may be picked up and placed on the circuit substrate, and then the LED die may be connected to the circuit substrate under heat and pressure. However, with such a simple method, throughput is restricted because heat and pressure has to be applied each time one LED die is mounted. 
         [0015]    As another possible method, a batch fabrication method often used in volume production may be employed. First, a large single substrate from which individual circuit substrates  502  are diced is prepared. Next, solder paste is applied to the electrodes of the LED dies  504   c  or to the electrodes formed on the large single substrate and, after tentatively connecting the electrodes of the LED dies  504   c  to the electrodes of the large single substrate by the solder paste, the solder paste is melted in a reflow oven, thus connecting a large number of LED dies  504   c  in a collective manner. Next, a transparent resin  508  is filled to seal the LED dies  504   c  therein. Finally, the large single substrate is diced into individual LED devices. In the above collective connection step, first the LED dies  504   c  on the upper surface are connected, and then the LED dies  504   c  on the lower surface are connected. That is, since this fabrication method requires that the substrate be passed through the reflow oven twice, not only does the fabrication process become long, but the fabrication conditions become complex. Furthermore, it is highly likely that the LED device  1  of  FIG. 26  may not be able to provide sufficient brightness, because only two LED dies  504   c  are mounted. 
         [0016]    In the case of the LED device (light source device  605 A) shown in  FIG. 27 , the brightness can be increased, since six LED dies (light emitting elements  606 ) are mounted. However, this LED device is not easy to fabricate because, similarly to the LED device of  FIG. 26 , the LED dies  606  are mounted inside the reflective recessed portions  604   d  formed in the circuit substrate (light emitting element mounting enamel substrate  601   a ). Furthermore, since each LED die  606  is connected to the electrode  607   c  of the circuit substrate  601   a  by a wire, the light emitting efficiency drops. 
         [0017]    It is an object of the present invention to provide a double-sided semiconductor light emitting device that is easy to fabricate even when semiconductor light emitting elements are flip-chip mounted, and a method for fabricating the same. 
         [0018]    It is another object of the present invention to provide a double-sided semiconductor light emitting device that is easy to fabricate even when four or more semiconductor light emitting elements are flip-chip mounted in order to increase the brightness. 
         [0019]    A semiconductor light emitting device includes, a plurality of leadframes, a plurality of semiconductor light emitting elements connected to the plurality of leadframes, and a covering member that covers the plurality of semiconductor light emitting elements, and wherein an end portion of one of the plurality of leadframes is located in close proximity to an end portion of another one of the plurality of leadframes, forming a gap therebetween, and the plurality of semiconductor light emitting elements are flip-chip mounted on the front and back surfaces of the one leadframe and that other leadframe in such a manner as to straddle the gap. 
         [0020]    Preferably, in the semiconductor light emitting device, the plurality of leadframes include a first leadframe and a second leadframe, the plurality of semiconductor light emitting elements include a first semiconductor light emitting element and a second semiconductor light emitting element, an end portion of the first leadframe is located in close proximity to an end portion of the second leadframe, forming a gap therebetween, the first semiconductor light emitting element is flip-chip mounted on first surfaces of the first and second leadframes in such a manner as to straddle the gap, the second semiconductor light emitting element is flip-chip mounted on second surfaces of the first and second leadframes in such a manner as to straddle the gap, and a portion of the first semiconductor light emitting element and a portion of the second semiconductor light emitting element are disposed facing each other. 
         [0021]    Preferably, in the semiconductor light emitting device, the plurality of leadframes include three leadframes, and the plurality of semiconductor light emitting elements form a series-parallel circuit. 
         [0022]    Preferably, in the semiconductor light emitting device, the plurality of semiconductor light emitting elements include four semiconductor light emitting elements, and the four semiconductor light emitting elements form a parallel circuit. 
         [0023]    Preferably, in the semiconductor light emitting device, the covering member includes a reflective member containing fine reflective particles and a fluorescent member containing a phosphor. 
         [0024]    Preferably, in the semiconductor light emitting device, the reflective member is disposed along outer peripheries of the plurality of leadframes and covers the side faces of the fluorescent member, the fluorescent member covers the top faces of the plurality of semiconductor light emitting elements, and a fluorescent resin is filled into space formed between the reflective member and the plurality of semiconductor light emitting elements and into space formed between the plurality of semiconductor light emitting elements that are mounted on the front and back surfaces of the plurality of leadframes so as to face each other. 
         [0025]    Preferably, in the semiconductor light emitting device, the fluorescent member covers the top faces of the plurality of semiconductor light emitting elements, and the reflective member is applied to cover the side faces of the plurality of semiconductor light emitting elements and to fill space formed between the plurality of semiconductor light emitting elements that are mounted on the front and back surfaces of the plurality of leadframes so as to face each other. 
         [0026]    Preferably, in the semiconductor light emitting device, a portion of the plurality of leadframes protrudes from the covering member. 
         [0027]    A semiconductor light emitting device fabrication method includes, a large-sized leadframe preparation step for preparing a large-sized leadframe from which leadframes to be included in each individual semiconductor light emitting device are diced, a first placement step for placing a plurality of semiconductor light emitting elements on a first adhesive sheet, a second placement step for placing a plurality of semiconductor light emitting elements on a second adhesive sheet, a first positioning step for positioning the first adhesive sheet with respect to the large-sized leadframe after the plurality of semiconductor light emitting elements have been placed on the first adhesive sheet, a second positioning step for positioning the second adhesive sheet with respect to the large-sized leadframe after the plurality of semiconductor light emitting elements have been placed on the second adhesive sheet, a connecting step for pressing together the first and second adhesive sheets onto the large-sized leadframe under heat and thereby connecting the plurality of semiconductor light emitting elements to the large-sized leadframe; a covering step for covering the plurality of semiconductor light emitting elements with a covering member after the plurality of semiconductor light emitting elements have been connected to the large-sized leadframe, and a dicing step for dicing the large-sized leadframe. 
         [0028]    Preferably, in the semiconductor light emitting device fabrication method, the covering member includes a reflective member containing fine reflective particles and a fluorescent member containing a phosphor, and the covering step covers the side faces of the plurality of semiconductor light emitting elements with the reflective member and covers the top faces of the plurality of semiconductor light emitting elements with the fluorescent member. 
         [0029]    Preferably, in the semiconductor light emitting device fabrication method, the reflective member is applied to the side faces of the plurality of semiconductor light emitting elements by using a squeegee. 
         [0030]    Preferably, in the semiconductor light emitting device fabrication method, the fluorescent member is a phosphor sheet, and the phosphor sheet is bonded to the top faces of the plurality of semiconductor light emitting elements. 
         [0031]    The semiconductor light emitting device can be fabricated by a batch fabrication method that uses two adhesive sheets and a large-sized leadframe, that performs the connection and covering in a collective manner, and that dices the completed large-sized leadframe into individual devices. In the batch fabrication method, since the heating step for connection can be accomplished in a single operation, not only can the process be shorted but the fabrication conditions can be prevented from becoming complex. As a result, a double-sided semiconductor light emitting device that is easy to fabricate can be provided. 
         [0032]    The semiconductor light emitting device can be fabricated using a simple fabrication method. That is, it can be fabricated by a batch fabrication method that includes the step of preparing two adhesive sheets and a large-sized leadframe and the collective connection step. Compared with the prior art fabrication method that includes a solder reflow step requiring that the heating step be performed twice in order to mount semiconductor light emitting elements on both sides of a circuit substrate, the batch fabrication method requires that the pressing and heating step be performed only once, which serves to not only shorten the fabrication process but also simplify the fabrication conditions. Furthermore, since the large-sized leadframe is a metal plate formed with openings, the preparatory step can be greatly simplified. Furthermore, the brightness of the semiconductor light emitting device can be increased, since four or more semiconductor light emitting elements are mounted and each semiconductor light emitting element is flip-chip mounted. 
         [0033]    According to the semiconductor light emitting device fabrication method, the batch fabrication method that uses adhesive sheets and a large-sized leadframe, that performs the connection and covering in a collective manner, and that dices the completed large-sized leadframe to obtain the desired product is improved so that the semiconductor light emitting elements can be mounted on both sides of the large-sized leadframe by using the two adhesive sheets. With this improved batch fabrication method, since the heating step for connection can be accomplished in a single operation, not only can the process be shorted but the fabrication conditions can be prevented from becoming complex. This serves to simplify the fabrication method of the double-sided semiconductor light emitting device. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0034]      FIG. 1  is a diagram showing the external appearance of an LED device  10 : part (a) is a top plan view, (b) is a front view, and (c) is a right side view. 
           [0035]      FIG. 2  is a cross-sectional view taken along line AA′ in  FIG. 1(   b ). 
           [0036]      FIG. 3  is a diagram showing the LED device  10  mounted on a mother substrate  35 . 
           [0037]      FIGS. 4(   a ) to  4 ( f ) are diagrams (part  1 ) for explaining a fabrication method for the LED device  10 . 
           [0038]      FIGS. 5(   g ) to  5 ( i ) are diagrams (part  2 ) for explaining the fabrication method for the LED device  10 . 
           [0039]      FIG. 6  is a plan view showing the positional relationship between a large-sized leadframe and LED dies. 
           [0040]      FIG. 7  is a diagram showing the external appearance of an LED device  70 : part (a) is a top plan view, (b) is a front view, and (c) is a right side view. 
           [0041]      FIG. 8  is a cross-sectional view taken along line BB′ in  FIG. 7(   b ). 
           [0042]      FIG. 9  is a diagram for explaining a fabrication method for the LED device  70 . 
           [0043]      FIG. 10  is a diagram showing the external appearance of an LED device  100 : part (a) is a perspective view, and (b) is a cross-sectional view taken along line CC′ in (a). 
           [0044]      FIG. 11  is a diagram showing an application example in which the LED device (semiconductor light emitting device)  100  is used in an area lighting device  110 : part (a) is a plan view, and (b) is a cross-sectional view taken along line DD′ in (a). 
           [0045]      FIG. 12  is a cross-sectional view of an LED device  120 . 
           [0046]      FIG. 13  is a diagram showing the external appearance of an LED device  200 : part (a) is a top plan view, (b) is a front view, and (c) is a right side view. 
           [0047]      FIG. 14  is a cross-sectional view taken along line EE′ in  FIG. 13(   b ). 
           [0048]      FIG. 15  is a circuit diagram of the LED device  200 . 
           [0049]      FIG. 16  is a diagram showing the LED device  200  mounted on a mother substrate  245 . 
           [0050]      FIG. 17  is a diagram for explaining a fabrication method for the LED device  200 . 
           [0051]      FIG. 18  is a diagram for explaining the positional relationship between a large-sized leadframe  251  and LED dies  215  and  216 . 
           [0052]      FIG. 19  is a diagram showing the external appearance of an LED device  270 : part (a) is a top plan view, (b) is a front view, and (c) is a right side view. 
           [0053]      FIG. 20(   a ) is a cross-sectional view taken along line HH′ in  FIG. 19(   b ), and  FIG. 20(   b ) is a front view showing the condition in which a covering member  273  on the front surface side of leadframes  271  and  272  has been removed from the condition shown in  FIG. 19(   b ). 
           [0054]      FIG. 21  is a circuit diagram of the LED device  270 . 
           [0055]      FIG. 22  is a diagram showing the external appearance of an LED device  300 : part (a) is a top plan view, (b) is a front view, and (c) is a right side view. 
           [0056]      FIG. 23  is a cross-sectional view taken along line II′ in  FIG. 22(   b ). 
           [0057]      FIG. 24  is a diagram for explaining a fabrication method for the LED device  300 . 
           [0058]      FIG. 25  is a diagram showing an LED device ( 1 ) according to the prior art. 
           [0059]      FIG. 26  is a diagram showing an LED device ( 2 ) according to the prior art. 
           [0060]      FIG. 27  is a diagram showing an LED device ( 3 ) according to the prior art. 
       
    
    
     DESCRIPTION 
       [0061]    A semiconductor light emitting device and a method for fabricating the semiconductor light emitting device will be described below with reference to the drawings. It will, however, be noted that the technical scope of the present invention is not limited by any particular embodiment described herein, but extends to the inventions described in the appended claims and their equivalents. Further, in the description of the drawings, the same or corresponding component elements are designated by the same reference numerals, and the description of such component elements, once given, will not be repeated thereafter. It will also be noted that the scale to which each component element is drawn is changed as needed for illustrative purposes. 
       First Embodiment 
       [0062]      FIG. 1  is a diagram showing the external appearance of an LED device (semiconductor light emitting device)  10 : part (a) is a top plan view, (b) is a front view, and (c) is a right side view. 
         [0063]    When the LED device  10  is viewed from the top, a leadframe  11  (first leadframe) and a leadframe  12  (second leadframe) are seen extending horizontally in a rectangular covering member  13  (see  FIG. 1(   a )). The leadframes  11  and  12  are arranged one adjacent to the other with their end portions in close proximity to each other. The other end portions of the leadframes  11  and  12  are flush with the respective side edges of the covering member  13 . When the LED device  10  is viewed from the front, only the covering member  13  is seen (see  FIG. 1(   b )). When the LED device  10  is viewed from the right side, the leadframe  12  is seen extending vertically in such a manner as to split the covering member  13  (see  FIG. 1(   c )). Though not shown here, the bottom view of the LED device  10  is the same as the top plan view of  FIG. 1(   a ). The left side view of the LED device  10  is similar to the right side view of  FIG. 1(   c ), except that the leadframe  11  is seen in place of the leadframe  12 . 
         [0064]      FIG. 2  is a cross-sectional view taken along line AA′ in  FIG. 1(   b ). 
         [0065]    The LED device  10  includes an LED die  14  (first semiconductor light emitting element) and an LED die  15  (second semiconductor light emitting element), in addition to the leadframes  11  and  12  and the covering member  13 . The LED dies  14  and  15  each comprise a sapphire substrate  16 , a semiconductor layer  17 , and protruding electrodes  18 . In the LED dies  14  and  15 , the face on which the semiconductor layer  17  is not formed is called the top face, and the face on which the semiconductor layer  17  and the protruding electrodes  18  are formed is called the bottom face, while the faces connecting between the top and bottom faces are called the side faces. 
         [0066]    In the LED dies  14  and  15 , the semiconductor layer  17  is formed on the underside of the sapphire substrate  16 , and the protruding electrodes  18  are attached to the semiconductor layer  17 . The sapphire substrate  16  is a transparent insulating substrate having a thickness of 80 to 120 μm. The semiconductor layer  17  includes an n-type semiconductor layer, a p-type semiconductor layer, an interlayer insulating film, and metal interconnects, and has a thickness slightly smaller than 10 μm. A light emitting layer is formed at the interface between the n-type semiconductor layer and the p-type semiconductor layer, and its plan shape is substantially equal to that of the p-type semiconductor layer. A portion of the n-type semiconductor layer and the p-type semiconductor layer are covered with the interlayer insulating film, and the metal interconnects are formed on the interlayer insulating film and are connected to the protruding electrodes  18 . To facilitate flip-chip mounting, the metal interconnects are clustered into an anode and a cathode, respectively, and are rearranged to form the protruding electrodes  18  on the left and right edge portions of the LED die  14 ,  15 . Each protruding electrode  18  is formed as a bump having a core of Cu or Au about 10 to 30 μm in size, and has an AuSn eutectic layer on the lower face thereof. 
         [0067]    Each of the leadframes  11  and  12  is formed from a copper plate plated with Ni, Ag, Au, or the like, and has a thickness of 100 to 400 μm. The gap  19  formed between the leadframes  11  and  12  is 200 to 400 μm in width. The LED die  14  is flip-chip mounted on the upper surfaces (first surfaces) of the leadframes  11  and  12  in such a manner as to straddle the gap  19 , while the LED die  15  is flip-chip mounted on the lower surfaces (second surfaces) of the leadframes  11  and  12  in such a manner as to straddle the gap  19 . The protruding electrodes  18  are rearranged on the bottom faces of the respective LED dies  14  and  15  so as to match the pitch. With the above arrangement, the LED dies  14  and  15  are placed with their designated portions facing each other. 
         [0068]    Of the portions of the leadframes  11  and  12 , the portions (cut faces) exposed to the outside environment should be plated with solder or the like. If the surfaces of the leadframes  11  and  12  are plated with Ag, then an inorganic transparent insulating film such as SiO2 should be formed over the entire surface of each of the leadframes  11  and  12 , except the mounting portions thereof, in order to prevent oxidation or sulfidization. Further, the protruding electrodes  18  should be connected to the leadframes  11  and  12  by AuSn eutectic or by a high-melting solder in order to prevent the connections from being melted at the reflow temperature applied when mounting the LED device  10  on a mother substrate. The covering member  13  is formed from a silicone resin containing phosphors. 
         [0069]      FIG. 3  is a diagram showing the LED device  10  mounted on a mother substrate  35 . 
         [0070]      FIG. 3  shows the LED device  10  as viewed from the front side. Mother substrate electrodes  33  and  34  are formed on the mother substrate  35 . The mother substrate electrode  33  is connected to the leadframe  11  (see  FIGS. 1 and 2 ) by a solder  31 . Similarly, the mother substrate electrode  34  is connected to the leadframe  12  (see  FIGS. 1 and 2 ) by a solder  32 . The solders  31  and  32  may each be formed not only on the bottom face of the LED device  10  but also halfway along the side face in order to increase the strength of the connection. The gap between the mother substrate electrodes  33  and  34  is made wider than the gap  19  (see  FIG. 2 ) in the LED device  10  in order to avoid short-circuiting due to the presence of foreign matter. 
         [0071]      FIGS. 4 and 5  are diagrams for explaining a fabrication method for the LED device  10 . 
         [0072]    First, a large-sized leadframe  41  from which the leadframes  11  and  12  to be included in each individual LED device  10  (see  FIGS. 1 and 2 ) are diced is prepared (large-sized leadframe preparation step) (see  FIG. 4(   a )). The large-sized leadframe  41  is a plate-like member on which a large number of LED dies  14  and  15  can be mounted, but for illustrative purposes,  FIGS. 4 and 5  show that only three of each of the LED dies  14  and  15  can be mounted (the same applies hereinafter). The large-sized leadframe  41  is prepared by etching a copper plate and forming openings in the desired positions, and the surface is plated after the etching. 
         [0073]    Next, the plurality of LED dies  14  are placed on a first adhesive sheet  42  (first placement step) (see  FIG. 4(   b )). The first adhesive sheet  42  is formed by forming an adhesive layer on the upper surface of a polyimide sheet. The LED dies  14  are picked up one at a time by a picker and placed one by one on the first adhesive sheet  42 . The LED dies  14  are placed with their top faces facing down (shown upside down in the figure) and bonded to the first adhesive sheet  42 . The LED dies  14  are arranged at the same pitch as the pitch of the mounting portions of the large-sized leadframe  41 . Further, each LED die  14  is oriented so that the anode and cathode are located at the desired positions. 
         [0074]    Next, the plurality of LED dies  15  are placed on a second adhesive sheet  43  (second placement step) (see  FIG. 4(   c )). In the second placement step, the plurality of LED dies  15  are placed on the second adhesive sheet  43  in a manner similar to the first placement step shown in  FIG. 4(   b ). The surface of the large-sized leadframe  41  onto which the second adhesive sheet  43  is laminated is opposite from the surface of the large-sized leadframe  41  onto which the first adhesive sheet  42  is laminated. The large-sized leadframe preparation step, the first placement step, and the second placement step need not necessarily be performed in the above-described order. 
         [0075]    Next, the first adhesive sheet  42  on which the plurality of LED dies  14  have been placed is positioned with respect to the large-sized leadframe  41  (first positioning step) (see  FIG. 4(   d )). The first adhesive sheet  42  is turned upside down, and is positioned accurately while observing the large-sized leadframe  41  through the optically transmissive first adhesive sheet  42 . When the positioning is complete, the first adhesive sheet  42  is tentatively fixed at the edges of the large-sized leadframe  41 . 
         [0076]    Next, the second adhesive sheet  43  on which the plurality of LED dies  15  have been placed is positioned with respect to the large-sized leadframe  41  (second positioning step) (see  FIG. 4(   e )). The large-sized leadframe  41  to which the first adhesive sheet  42  has been tentatively fixed is turned upside down. At this time, the first adhesive sheet  42  is in contacting relationship with the large-sized leadframe  41 . Similarly to the first positioning step, the second adhesive sheet  43  is turned upside down, and is positioned accurately while observing the large-sized leadframe  41  through the second adhesive sheet  43 . When the positioning is complete, the second adhesive sheet  43  is tentatively fixed at the edges of the large-sized leadframe  41 . 
         [0077]    Then, the first and second adhesive sheets  42  and  43  and the large-sized leadframe  41  are pressed together under heat, thus connecting the LED dies  14  and  15  to the large-sized leadframe  41  (connecting step) (see  FIG. 4(   f )).  FIG. 4(   f ) shows the structure upside down from that shown in  FIG. 4(   e ). The large-sized leadframe  41  to which the first and second adhesive sheets  42  have been tentatively fixed is placed on a table (not shown), and the first and second adhesive sheets  42  and the large-sized leadframe  41  are pressed together by using a pressing head (not shown). While maintaining the pressure, the pressing head is heated to a temperature of about 300 to 350° C. Since the AuSn eutectic melts at this temperature, the temperature of the pressing head is lowered after a predetermined time has elapsed and, after that, the pressing head is removed from the large-sized leadframe  41 , etc. 
         [0078]    Next, the first and second adhesive sheets  42  and  43  are removed from the large-sized leadframe  41  to which the LED dies  14  and  15  have been connected, and the leadframe  41  is placed into a pair of mold halves  44  and  45  (covering step) (see  FIG. 5(   g )). Though not shown here, the edges of the large-sized leadframe  41  are supported by the mold halves  44  and  45 . If the supporting is not sufficient, a supporting structure may be provided within the mold  44 ,  45 . After the large-sized leadframe  41  has thus been placed into the mold, a covering member  46  is formed by injection molding. 
         [0079]    After that, the large-sized leadframe  41  is removed from the mold  44 ,  45  (see  FIG. 5(   h )). 
         [0080]    Finally, the large-sized leadframe  41  is diced into individual LED devices  10  (dicing step) (see  FIG. 5(   i )). The large-sized leadframe  41  covered as described above is attached to a dicing sheet (not shown), and the large-sized leadframe  41  is cut by a dicer to separate each individual LED device  10 . 
         [0081]      FIG. 6  is a plan view showing the positional relationship between the large-sized leadframe and the LED dies. 
         [0082]      FIG. 6  shows a portion of the large-sized leadframe  41  as viewed from the top by removing the covering member  46  in  FIG. 5(   h ). On the large-sized leadframe  41 , the LED dies  14  are arranged in a lattice pattern. The large-sized leadframe  41  is shown as if it is constructed from an array of copper plates each extending vertically in the figure. Though not shown here, the copper plates are actually connected together at their upper or lower ends. In the figure, the protruding electrodes  18  located on the other side of the sapphire substrate  16  are indicated by dotted lines. 
       Second Embodiment 
       [0083]    In the LED device  10  described above, light is also emitted in a direction parallel to the leadframes  11  and  12 . Depending on the application of the LED device  10 , this emitted light may not only be difficult to utilize but also be detrimental. For example, in the LED device  10 , if the distance that the light emitted in the direction vertical to the leadframes  11  and  12  travels through the covering member  13  differs from the distance that the light emitted in the horizontal direction travels through the covering member  13 , the amount of wavelength conversion that the light undergoes while passing through the phosphors becomes different. As a result, in the LED device  10 , the color of the emitted light may be different depending on the direction in which it is emitted. In view of this, the following description deals with an LED device (semiconductor light emitting device)  70  which does not emit light in the direction parallel to the leadframes  11  and  12  but emits light only in the direction vertical to the leadframes  11  and  12 . In the LED device  70 , the same component elements as those of the LED device  10  are designated by the same reference numerals. 
         [0084]      FIG. 7  is a diagram showing the external appearance of the LED device  70 : part (a) is a top plan view, (b) is a front view, and (c) is a right side view. 
         [0085]    When the LED device  70  is viewed from the top, phosphor sheets  71  and  73  and a reflective member  72  sandwiched between the phosphor sheets  71  and  73  are seen in addition to the leadframe  11  (first leadframe) and leadframe  12  (second leadframe) extending horizontally in the reflective member  72  (see  FIG. 7(   a )). The leadframes  11  and  12  are arranged one adjacent to the other with their end portions in close proximity to each other. The other end portions of the leadframes  11  and  12  are flush with the left and right side edges of the phosphor sheets  71  and  73  and the reflective member  72 . When the LED device  70  is viewed from the front, only the phosphor sheet  73  is seen (see  FIG. 7(   b )). When the 
         [0086]    LED device  70  is viewed from the right side, the phosphor sheets  71  and  73  and the reflective member  72  sandwiched between the phosphor sheets  71  and  73  are seen in addition to the leadframe  12  embedded in the reflective member  72  (see  FIG. 7(   c )). Though not shown here, the bottom view of the LED device  70  is the same as the top plan view of  FIG. 7(   a ). The left side view of the LED device  70  is similar to the right side view of  FIG. 7(   c ), except that the leadframe  11  is seen in place of the leadframe  12 . 
         [0087]      FIG. 8  is a cross-sectional view taken along line BB′ in  FIG. 7(   b ). 
         [0088]    The LED device  70  includes the leadframes  11  and  12 , the reflective member  72 , the phosphor sheets  71  and  73 , the LED die  14  (first semiconductor light emitting element), and the LED die  15  (second semiconductor light emitting element). Similarly to the LED device  10  (see  FIG. 2 ), the LED die  14  is flip-chip mounted on the upper surfaces (first surfaces) of the leadframes  11  and  12  in such a manner as to straddle the gap  19 . Further, the LED die  15  is flip-chip mounted on the lower surfaces (second surfaces) of the leadframes  11  and  12  in such a manner as to straddle the gap  19 . The leadframes  11  and  12  and the LED dies  14  and  15  are the same between the LED device  70  and the LED device  10 . The surface treatment of the leadframes  11  and  12  and the connecting structure connecting the LED dies  14  and  15  to the leadframes  11  and  12  are also the same between the LED device  70  and the LED device  10 . 
         [0089]    The bottom and side faces of the LED dies  14  and  15  are covered with the reflective member  72 , while the top faces of the LED dies  14  and  15  are covered with the respective phosphor sheets  71  and  73 . That is, in the LED device  70 , the reflective member  72  and the phosphor sheets  71  and  73  together constitute the covering member. The reflective member  72  is formed by mixing fine reflective particles such as titanium oxide or alumina into a binder such as a silicone resin or organopolysiloxane, kneading the mixture, and curing the mixture. The phosphor sheets  71  and  73  are each formed by mixing phosphors into a silicone resin, kneading the mixture, and curing the mixture. The phosphor sheets  71  and  73  are bonded to the reflective member  72  and the top faces of the respective LED dies  14  and  15  by a transparent adhesive (not shown). 
         [0090]      FIG. 9  is a diagram for explaining a fabrication method for the LED device  70 . 
         [0091]    The fabrication method of the LED device  70  employs the same steps as the large-sized leadframe preparation step (see  FIG. 4(   a ), the first placement step (see  FIG. 4(   b )), the second placement step (see  FIG. 4(   c )), the first positioning step (see  FIG. 4(   d )), the second positioning step (see  FIG. 4(   e )), and the connecting step (see  FIG. 4(   f )) shown in the fabrication method of the LED device  10 , and therefore, the description of these steps will not be repeated here. 
         [0092]      FIG. 9(   a ) is the same diagram as that shown in  FIG. 4(   f ), and shows the starting step (initial condition) of the process that characterizes the fabrication method of the LED device  70 . 
         [0093]    From the condition shown in  FIG. 9(   a ), only the first adhesive sheet  42  is removed (first substep) (see  FIG. 9(   b )).  FIGS. 9(   b ),  9 ( c ), and  9 ( d ) show three substeps constituting the covering step for covering the LED dies  14  and  15  with a reflective member  92  and phosphor sheets  91  and  93 . 
         [0094]    Next, the reflective member  92  before curing is filled into the space between the LED dies  14 ,  15  to cover the bottom and side faces of the LED dies  14 ,  15  (second substep) (see  FIG. 9(   c )). After filling, the reflective member  92  is cured at about 150° C. The reflective member  92  can be applied using a squeegee, and the portions of the reflective member  92  that remain on the top faces of the LED dies  14  after curing are removed by polishing. Alternatively, the reflective member  92  whose amount is accurately measured using a dispenser may be applied. In that case, there is no need to polish the top faces of the LED dies  14 . 
         [0095]    Next, the top faces of the LED dies  14  and  15  are covered with the respective phosphor sheets  91  and  93  (third substep) (see  FIG. 9(   d )). A transparent adhesive material is applied over the top faces of the LED dies  14  as well as the upper surface of the reflective member  92 , and the phosphor sheet  91  is bonded. In parallel with this substep, the second adhesive sheet  43  is removed, a transparent adhesive material is applied over the top faces of the LED dies  15  as well as the surface (the lower surface in the figure) of the reflective member  92 , and the phosphor sheet  93  is bonded. Instead of forming the phosphor sheets  91  and  93 , a fluorescent resin prepared by mixing phosphors into a transparent binder such as silicone may be applied over the top faces of the LED dies  14  and  15  as well as the surfaces of the reflective member  92 , the resin then being cured to form phosphor layers, and the thus formed phosphor layers may be used as the fluorescent members for covering the top faces of the LED dies  14  and  15 . However, when the phosphor sheets  91  and  93  are used as the fluorescent members, the advantage is that the covering step can be accomplished in a short time, because the covering by the reflecting member  92  can be performed concurrently with the preparation of the phosphor sheets  91  and  93 . 
         [0096]    Finally, the large-sized leadframe  41  covered as described above is diced into individual LED devices  70  (dicing step) (see  FIG. 9(   e )).  FIG. 9(   e ) shows the same step as the dicing step of  FIG. 5(   i ), except that the covering member used is different. 
         [0097]    In the LED devices  10  and  70  described above, the two LED dies  14  and  15  are connected in parallel. In this case, the forward voltage drop of the LED die  14  must be made equal to that of the LED die  15 . For example, in the fabrication process, the difference in forward voltage drop is held to within 0.1 V. That is, after dicing the wafer containing a large number of LED dies, the LED dies are sorted out according to the forward voltage drop. If the first and second placement steps are performed while sorting out the LED dies, the pickup job can be standardized, and the fabrication process can be shortened. 
         [0098]    In the LED device  70 , the side faces of the LED dies  14  and  15  are covered with the reflective member  72 , and the phosphor sheets  71  and  73  are bonded to the upper and lower surfaces of the reflective member  72  as well as to the top faces of the respective LED dies  14  and  15  (see  FIG. 8 ) so that the light can be emitted only in the direction vertical to the leadframes  11  and  12 . If the light is to be emitted only in the direction vertical to the leadframes  11  and  12 , the reflective member may be provided not only on the side faces of the LED dies to which the fluorescent members are laminated but also on the side faces of the fluorescent members laminated to the top faces of the respective LED dies. To fabricate such an LED device, a phosphor layer is formed in advance on the sapphire substrate at the wafer level, and then the wafer is diced into individual LED dies each covered with the phosphor layer. Next, such LED dies are mounted on the large-sized leadframe by using two adhesive sheets, as shown in the fabrication method of the LED device  10 . Then, the reflective member is filled into the space surrounding the respective LED dies. Finally, the large-sized leadframe is diced to separate each individual LED device. It is preferable that the binder to be used in the phosphor layer is selected from among transparent inorganic materials such as glass that can withstand the temperature applied when joining the LED dies to the large-sized leadframe. 
       Third Embodiment 
       [0099]    In the LED devices  10  and  70  described above, the cut faces of the leadframes  11  and  12  are made flush with the cut faces of the covering member  13  (the reflective member  72  in the case of the LED device  70 ). When mounting the LED device  10  or  70  on a mother substrate, if the strength is not sufficient, the end portions of the respective leadframes  11  and  12  may be made to protrude from the respective cut faces of the covering member  13  (the reflective member  72  in the second embodiment). The following description therefore deals with an LED device (semiconductor light emitting device)  100  in which the leadframes  11  and  12  are made to extend (protrude) horizontally from the covering member. In the LED device  100 , the same component elements as those of the LED device  10  are designated by the same reference numerals. 
         [0100]      FIG. 10  is a diagram showing the external appearance of the LED device  100 : part (a) is a perspective view, and (b) is a cross-sectional view taken along line CC′ in (a). 
         [0101]    The LED device  100  is identical to the LED device  10 , except that the left and right end portions of the respective leadframes  11  and  12  are made to protrude from the covering member  101 . That is, in the LED device  100 , the two flat plate-like leadframes  11  and  12  are embedded in the covering member  101 , and the left and right end portions of the respective leadframes protrude from the covering member  101 . As shown, the upper edge faces of the leadframes  11  and  12  are flush with the upper face of the covering member  101 , and similarly, the lower edge faces of the leadframes  11  and  12  are flush with the lower face of the covering member  101 . The LED dies  14  and  15  are flip-chip mounted on the upper and lower surfaces of the leadframes  11  and  12  in such a manner as to straddle the gap between the leadframes. The covering member  101  is formed from a fluorescent resin prepared by mixing phosphors into a silicone resin and curing the mixture. The leadframes  11  and  12  and the LED dies  14  and  15  are the same between the LED device  100  and the LED device  10 . The surface treatment of the leadframes  11  and  12  and the connecting structure connecting the LED dies  14  and  15  to the leadframes  11  and  12  are also the same between the LED device  100  and the LED device  10 . 
         [0102]    The fabrication method of the LED device  100  is such that, after completing the fabrication of the large-sized leadframe  41  covered with the covering member  46  as shown in  FIG. 5(   h ) for the LED device  10 , the covering member  46  is partially removed by cutting or the like so as to expose the large-sized leadframe in the desired positions, thus forming the covering member  101 . After that, the large-sized leadframe  41  is diced while leaving the protruding portions exposed, to complete the fabrication of the LED device  100 . 
         [0103]    In the LED device  100 , the protruding portions of the leadframes  11  and  12  may be bent to conform to the side faces of the LED device  100 . Further, in the LED device  10 , the LED dies  14  and  15  have been described as being connected to the leadframes  11  and  12  by AuSn eutectic, but instead, a high-melting solder may be used to connect them. The high-melting solder used here is an alloy having a higher melting point than the solder used to mount the LED device to the mother substrate. 
         [0104]      FIG. 11  is a diagram showing an application example in which the LED device  100  is used in an area lighting device  110 : part (a) is a plan view, and (b) is a cross-sectional view taken along line DD′ in (a). 
         [0105]    As shown in  FIG. 11(   a ), the area lighting device  110  includes a light conducting plate  111  having an opening  112 , and the LED device  100  is mounted in the opening  112 . The LED device  100  is connected electrically and mechanically to a mounting substrate  113  disposed under the light conducting plate  111 . A portion of the surface of the mounting substrate  113  is exposed in the opening  112 . 
         [0106]    In the area lighting device  110 , the light emitted from the LED device  100  in the left and right directions in the figure is introduced into the light conducting plate  111 . While propagating through the light conducting plate  111 , the direction of propagation of the introduced light is changed by the diffusing particles contained in the light conducting plate  111 , and the light emerges from the upper surface of the light conducting plate  111 . Any portion of the light directed toward the lower surface of the mounting substrate  113  is redirected upward by being reflected by a reflective layer provided on the upper surface of the mounting substrate  113  or on the lower surface of the light conducting plate  111 . While the light conducting plate  111  of the area lighting device  110  has been described as being provided with only one opening  112 , the light conducting plate  111  may be provided with a plurality of openings, and the LED device  100  may be mounted in each opening. 
       Fourth Embodiment 
       [0107]    In the LED device  100 , since the covering member  101  consists only of the fluorescent resin, light is emitted from all the faces of the LED device  100 . In this case, the optical path length that the light travels through the fluorescent resin constituting the covering member  101  differs between the light emitted from the front face and the light emitted from the side face, and a difference may arise in the amount of wavelength conversion that the light undergoes while passing through the fluorescent resin. This leads to the problem that, in the LED device  100 , the color of the light emitted from the front face differs from the color of the light emitted from the side face. The following description therefore deals with an LED device (semiconductor light emitting device)  120  in which the light emitting faces are limited to the front and back faces. In the LED device  120 , the same component elements as those of the LED device  10  are designated by the same reference numerals. 
         [0108]      FIG. 12  is a cross-sectional view of the LED device  120 . 
         [0109]    The external appearance of the LED device  120  is the same as that of the LED device  100  shown in  FIG. 10(   a ); therefore, the cross-sectional view of the LED device  120  shown in  FIG. 12  corresponds to the cross-sectional view taken along line CC′ in  FIG. 10(   a ). The difference between the LED device  120  and the LED device  100  is that, in the LED device  120 , the covering member comprises a plurality of members. In the LED device  120 , the covering member comprises a fluorescent resin  122  filled so as to cover the side faces and bottom faces of the LED dies  14  and  15  mounted on the two flat plate-like leadframes  11  and  12 , phosphor sheets  121  covering the top faces of the respective LED dies  14  and  15  as well as the fluorescent resin  122 , and a frame-like reflective member  123  formed so as to surround the fluorescent resin  122  and the phosphor sheets  121 . In each of the LED dies  14  and  15 , the top face refers to the face located on the sapphire substrate  16  side. 
         [0110]    The fabrication method of the LED device  120  is such that, after mounting the LED dies  14  and  15  on the respective surfaces of the large-sized leadframe  41  as shown in  FIG. 4(   f ), the fluorescent member  122  is filled into the space between the LED devices (in the left/right and up/down directions in the cross-sectional view) by using a mold or a squeegee, and then the material is cured. Next, the phosphor sheets  121  are laminated onto the fluorescent resin  122  and the sapphire substrates  16  of the top and bottom LED dies  14  and  15 . Then, a groove is formed between each LED die so as to expose the large-sized leadframe  41 , and a white reflective member is filled into the groove and cured. When the fabrication of the large-sized leadframe  41  thus covered is completed, the white reflective member is partially removed by cutting or the like so as to expose the large-sized leadframe in the desired positions; after that, the large-sized leadframe  41  is diced while leaving the protruding portions exposed, to complete the fabrication of the LED device  120 . The white reflective member remaining after dicing is the reflective member  123  of the LED device  120 . 
         [0111]    In the LED device  120 , the space between the reflective member  123  and the side faces of the LED dies  14  and  15  and the space between the bottom faces of the LED dies  14  and  15  are filled with the fluorescent resin  122 . Accordingly, the light emitted from the side face or bottom face of each of the LED dies  14  and  15  undergoes reflection while propagating through the fluorescent resin  122  and emerges from the front face or back face of the LED device  120 ; in the process, some of the light is wavelength-converted. 
         [0112]    In the LED device  70  shown in  FIG. 7 , since the white reflective member  72  directly covers the side and bottom faces of the LED device  70 , the light trying to emerge from the side and bottom faces is reflected back into the LED die  14  or  15 . As a result, the light is reabsorbed into the light emitting layer or scattered off as stray light, resulting in light emission loss. By contrast, in the LED device  120 , since most of the light emitted from the side and bottom faces is not reflected back into the LED die  14  or  15 , the light emission efficiency increases. Furthermore, the wavelength-converted light, if reflected back into the LED die  14  or  15 , is not reabsorbed into the light emitting layer. This also contributes to increasing the light emission efficiency. If the wavelength converting function is not needed in the covering member, the fluorescent resin  122  used as the covering member may be replaced by a transparent member. However, in this case, the light emission efficiency slightly drops. 
         [0113]    In the LED device  120 , the fluorescent resin may be used in place of the phosphor sheets  121  covering the top faces of the LED dies  14  and  15 . In that case, the phosphor sheet laminating step can be omitted. In the fabrication method of the LED device  120  described above, if the fluorescent resin  122  remains on the top faces of the LED dies  14  and  15  before laminating the phosphor sheets  121  thereon, it is preferable to remove the remaining fluorescent resin by, for example, polishing the top faces of the LED dies  14  and  15 . If the fluorescent resin  122  is used in place of the phosphor sheets  121  to cover the top faces of the LED dies  14  and  15 , this polishing step can also be omitted. On the other hand, since the phosphor sheets  121  are inexpensive, a set of phosphor sheets having different wavelength conversion characteristics may be prepared in advance so that the phosphor sheets that match the light emission characteristics (peak wavelength, etc.) of the LED dies  14  and  15  can be selected as desired from the set. In this way, when the phosphor sheets are used, it becomes easier to manage the color of emission of the LED device. 
         [0114]    In the LED device  120 , the white reflective member has been formed in a frame-like shape. However, the method of limiting the light emitting faces is not limited to providing a frame-like reflective member. For example, reflective members may be formed using the white reflective member only on the top and bottom faces of the LED device  120  (in the cross-sectional view, in the direction vertical to the plane of the figure) so that the light can be emitted only from the side faces (in the cross-sectional view, in the direction parallel to the plane of the figure). 
       Fifth Embodiment 
       [0115]      FIG. 13  is a diagram showing the external appearance of an LED device  200 : part (a) is a top plan view, (b) is a front view, and (c) is a right side view. 
         [0116]    When the LED device (semiconductor light emitting device)  200  is viewed from the top, leadframes  211 ,  212 , and  213  are seen extending horizontally in a rectangular covering member  214  (see  FIG. 13(   a )). The leadframes  211 ,  212 , and  213  are arranged one adjacent another with their end portions in close proximity to each other. The left side edge of the leadframe  211  and the right side edge of the leadframe  213  are flush with the respective side edges of the covering member  214 . When the LED device  200  is viewed from the front, only the covering member  214  is seen (see  FIG. 13(   b )). When the LED device  200  is viewed from the right side, the leadframe  213  is seen extending vertically in such a manner as to split the covering member  214  (see  FIG. 13(   c )). Though not shown here, the bottom view of the LED device  200  is the same as the top plan view of  FIG. 13(   a ). The left side view of the LED device  200  is similar to the right side view of  FIG. 13(   c ), except that the leadframe  211  is seen in place of the leadframe  213 . 
         [0117]      FIG. 14  is a cross-sectional view taken along line EE′ in  FIG. 13(   b ). 
         [0118]    The LED device  200  includes LED dies  215 ,  216 ,  217  and  218 , in addition to the leadframes  211 ,  212 , and  213  and the covering member  214 . The LED dies  215  to  218  each comprise a sapphire substrate  231 , a semiconductor layer  232 , and protruding electrodes  233 . In the LED dies  215  to  218 , the face on which the semiconductor layer  232  is not formed is called the top face, and the face on which the semiconductor layer  232  and the protruding electrodes  233  are formed is called the bottom face, while the faces connecting between the top and bottom faces are called the side faces. 
         [0119]    In the LED dies  215  to  218 , the semiconductor layer  232  is formed on the underside of the sapphire substrate  231 , and the protruding electrodes  233  are attached to the semiconductor layer  232 . The sapphire substrate  231  is a transparent insulating substrate having a thickness of 80 to 120 μm. The semiconductor layer  232  includes an n-type semiconductor layer, a p-type semiconductor layer, an interlayer insulating film, and metal interconnects, and has a thickness slightly smaller than 10 μm. A light emitting layer is formed at the interface between the n-type semiconductor layer and the p-type semiconductor layer, and its plan shape is substantially equal to that of the p-type semiconductor layer. A portion of the n-type semiconductor layer and the p-type semiconductor layer are covered with the interlayer insulating film, and the metal interconnects are formed on the interlayer insulating film. The metal interconnects are connected to the protruding electrodes  233 . To facilitate flip-chip mounting, the metal interconnects are clustered into an anode and a cathode, respectively, and are rearranged to form the protruding electrodes  233  on the left and right edge portions of each of the LED dies  215  to  218 . Each protruding electrode  233  is formed as a bump having a core of Cu or Au about 10 to 30 μm in size, and has an AuSn eutectic layer on the lower face thereof. 
         [0120]    Each of the leadframes  211  to  213  is formed from a copper plate plated with Ni, Ag, Au, or the like, and has a thickness of 100 to 400 μm. The gap  219  formed between the respective leadframes  211  to  213  is 200 to 400 μm in width. The LED die  215  is flip-chip mounted on the upper surfaces (hereinafter called the front surfaces) of the leadframes  211  and  212  in such a manner as to straddle the gap  219 . Further, the LED die  216  is flip-chip mounted on the front surfaces of the leadframes  212  and  213  in such a manner as to straddle the gap  219 . Similarly, the LED die  217  is flip-chip mounted on the lower surfaces (hereinafter called the back surfaces) of the leadframes  211  and  212  in such a manner as to straddle the gap  219 . Further, the LED die  218  is flip-chip mounted on the back surfaces of the leadframes  212  and  213  in such a manner as to straddle the gap  219 . The protruding electrodes  233  are rearranged on the bottom face of each of the LED dies  215  to  218  so as to be able to straddle the gap  219  without any problem. 
         [0121]    Of the portions of the leadframes  211  to  213 , the portions (cut faces) exposed to the outside environment are preferably plated with solder or the like. If the surfaces of the leadframes  211  to  213  are plated with Ag, it is preferable to form an inorganic transparent insulating film such as SiO2 over the entire surface of each of the leadframes  211  to  213 , except the mounting portions thereof, in order to prevent oxidation or sulfidization. Further, the protruding electrodes  233  should be connected to the leadframes  11  and  12  by AuSn eutectic as in the present embodiment or by a high-melting solder in order to prevent the connections from being melted at the reflow temperature applied when mounting the LED device  200  on a mother substrate. The covering member  214  is formed from a silicone resin containing phosphors. 
         [0122]      FIG. 15  is a circuit diagram of the LED device  200 . 
         [0123]    In the LED device  200 , the LED dies  215  and  217  are connected in parallel, the LED dies  216  and  218  are also connected in parallel, and the two parallel circuits are connected in series. That is, the LED dies  215  to  218  form a series-parallel circuit, and the anode and cathode of the series-parallel circuit respectively correspond to the leadframes  211  and  213 . The intermediate connection corresponds to the leadframe  212 . 
         [0124]      FIG. 16  is a diagram showing the LED device  200  mounted on a mother substrate  245 . 
         [0125]      FIG. 16  shows the LED device  200  as viewed from the front side. Mother substrate electrodes  243  and  244  are formed on the mother substrate  245 . The mother substrate electrode  243  is connected to the leadframe  211  (see  FIG. 13 ) by a solder  241 . On the other hand, the mother substrate electrode  244  is connected to the leadframe  213  (see  FIG. 13 ) by a solder  242 . Preferably, the solders  241  and  242  are each formed not only on the bottom face of the LED device  200  but also halfway along the side face in order to increase the strength of the connection. The gap between the mother substrate electrodes  243  and  244  is made wider than the gap between the leadframes  211  and  213  (see  FIG. 13 ) exposed in the bottom of the LED device  200  in order to avoid short-circuiting due to the presence of foreign matter. 
         [0126]      FIG. 17  is a diagram for explaining a fabrication method for the LED device  200 . 
         [0127]    First, a large-sized leadframe  251  is prepared (see  FIG. 17(   a )). The large-sized leadframe  251  is eventually cut apart to obtain the leadframes  211  to  213  (see  FIG. 13)  to be included in each individual LED  200 . The large-sized leadframe  251  is a plate-like member on which a large number of LED dies  215  to  218  can be mounted, but for illustrative purposes,  FIG. 17  shows that only two of each of the LED dies  215  to  218  can be mounted (the same applies hereinafter). The large-sized leadframe  251  is prepared by etching a copper plate and forming openings in the desired positions, and the surface is plated after the etching. 
         [0128]    Next, the plurality of LED dies  215  and  216  are placed on an adhesive sheet  252  (see  FIG. 17(   b )). The adhesive sheet  252  is formed by forming an adhesive layer on the upper surface of a polyimide sheet. The LED dies  215  and  216  are picked up one at a time by a picker and placed one by one on the adhesive sheet  252 . The LED dies  215  and  216  are placed with their top faces facing down (shown upside down in the figure) and bonded to the adhesive sheet  252 . The LED dies  215  and  216  are arranged at the same pitch as the pitch of the mounting portions on the front surface of the large-sized leadframe  251 . Further, each of the LED dies  215  and  216  is oriented so that the anode and cathode are located at the desired positions. 
         [0129]    Next, the plurality of LED dies  217  and  218  are placed on an adhesive sheet  253  (see  FIG. 17(   c )). In this step, the plurality of LED dies  217  and  218  are placed on the adhesive sheet  253  in a manner similar to the step shown in  FIG. 17(   b ). The pitch and orientation of the LED dies  217  and  218  are made to match the mounting portions on the back surface of the large-sized leadframe  251 . The steps shown in  FIGS. 17(   a ) to  17 ( c ) need not necessarily be performed in the above-described order. 
         [0130]    Next, the adhesive sheet  252  on which the plurality of LED dies  215  and  216  have been placed and the adhesive sheet  253  on which the plurality of LED dies  217  and  218  have been placed are positioned with respect to the large-sized leadframe  251 , and the adhesive sheets  252  and  253  are the large-sized leadframe  251  are pressed together under heat (see  FIG. 17(   d )). That is, this step is the step of connecting the LED dies  215  to  218  to the large-sized leadframe  251 . The adhesive sheet  252  is turned upside down, and is positioned accurately while observing the large-sized leadframe  251  through the optically transmissive adhesive sheet  252 . When the positioning is complete, the adhesive sheet  252  is tentatively fixed at the edges of the large-sized leadframe  252 . Next, the large-sized leadframe  252  to which the adhesive sheet  252  has been tentatively fixed is turned upside down. In the same manner as the above positioning step, the adhesive sheet  253  is turned upside down, and is positioned accurately while observing the large-sized leadframe  251  through the adhesive sheet  253 . When the positioning is complete, the adhesive sheet  253  is tentatively fixed at the edges of the large-sized leadframe  252 . The large-sized leadframe  251  to which the adhesive sheets  252  and  253  have been tentatively fixed is placed on a table, and the adhesive sheets  252  and  253  and the large-sized leadframe  251  are pressed together by using a pressing head; then, while maintaining the pressure, the pressing head is heated to a temperature of about 300 to 350° C. Since the AuSn eutectic melts at this temperature, the temperature of the pressing head is lowered after a predetermined time has elapsed and, after that, the pressing head is removed from the large-sized leadframe  251 , etc. In FIG.  17 ( d ), the adhesive sheet  252  is shown at the top to depict the condition after the connections have been made. 
         [0131]    Next, the LED dies  215  to  218  are covered with a covering member  254  (see  FIG. 17(   e )). The adhesive sheets  252  and  253  are removed from the large-sized leadframe  251  to which the LED dies  215  to  218  have been connected, and the LED dies  215  to  218  are covered with the covering member  254 . A mold may be used to apply the covering. In that case, after placing the large-sized leadframe  251  into the mold, the covering member  254  is formed by injection molding.  FIG. 17(   e ) shows the large-sized leadframe  251  after the covering. 
         [0132]    Finally, the large-sized leadframe  251  is diced into individual LED devices  200  (see  FIG. 17(   f )). The large-sized leadframe  251  covered as described above is attached to a dicing sheet, and the large-sized leadframe  251  is cut by a dicer to separate each individual LED device  200 . 
         [0133]      FIG. 18  is a diagram for explaining the positional relationship between the large-sized leadframe  251  and the LED dies  215  and  216 . 
         [0134]      FIG. 18  is a top plan view showing a portion of the large-sized leadframe  251  as viewed from the top by removing the adhesive sheet  252  in  FIG. 17(   d ). On the large-sized leadframe  251 , the LED dies  215  and  216  are arranged in a lattice pattern. The large-sized leadframe  251  is shown as if it is constructed from an array of copper plates each extending vertically in the figure. Though not shown here, the copper plates are actually connected together at their upper or lower ends. In  FIG. 18 , the protruding electrodes  233  located on the other side of the sapphire substrate  231  are indicated by dotted lines. The LED device  200  is obtained by cutting the portion indicated by F from the large-sized leadframe  251  after the covering.  FIG. 18  also shows reference characters  284 ,  286 , and G which are used for the explanation of a sixth embodiment to be described hereinafter. 
       Sixth Embodiment 
       [0135]    In the LED device  200 , the LED dies  215  to  218  have been connected in series and parallel. If the brightness of the LED device is to be increased by increasing the number of LED dies, the method of connecting the LED dies need not be limited to a series-parallel connection, but they may be connected in parallel. The following description therefore deals with an LED device (semiconductor light emitting device)  270  in which the LED dies are connected in parallel. 
         [0136]      FIG. 19  is a diagram showing the external appearance of the LED device  270 : part (a) is a top plan view, (b) is a front view, and (c) is a right side view. 
         [0137]    When the LED device  270  is viewed from the top, leadframes  271  and  272  are seen extending horizontally in a rectangular covering member  273  (see  FIG. 19(   a )). The leadframes  271  and  272  are arranged one adjacent to the other with their end portions in close proximity to each other. The left side edge of the leadframe  271  and the right side edge of the leadframe  272  are flush with the respective side edges of the covering member  273 . When the LED device  270  is viewed from the front, only the covering member  273  is seen (see  FIG. 19(   b )). When the LED device  270  is viewed from the right side, the leadframe  272  is seen extending vertically in such a manner as to split the covering member  273  (see  FIG. 19(   c )). Though not shown here, the bottom view of the LED device  270  is the same as the top plan view of  FIG. 19(   a ). The left side view of the LED device  270  is similar to the right side view of  FIG. 19(   c ), except that the leadframe  271  is seen in place of the leadframe  272 . 
         [0138]      FIG. 20(   a ) is a cross-sectional view taken along line HH′ in  FIG. 19(   b ).  FIG. 20(   b ) is a front view showing the condition in which the covering member  273  on the front surface side of the leadframes  271  and  272  has been removed from the condition shown in  FIG. 19(   b ). 
         [0139]    As shown in  FIG. 20(   a ), the LED device  270  includes LED dies  284 ,  285 ,  286 , and  287 , in addition to the leadframes  271  and  272  and the covering member  273 . In  FIG. 20(   a ), the LED dies  286  and  287  are not shown because they are occluded by the LED dies  284  and  285 , respectively. The LED dies  284  to  287  are the same as the LED dies  215  to  218  contained in the LED device  200 , and the leadframes  271  and  272  and the covering member  273  are respectively formed from the same materials as those used for the leadframes  211  to  231  and the covering members  214  in the LED device  200 . 
         [0140]    As shown in  FIG. 20(   b ), the covering member  273  is seen exposed in a gap  279  created between the vertically extending leadframes  271  and  272 . The LED dies  284  and  286  are both connected to the leadframes  271  and  272  in such a manner as to straddle the gap  279 . Though not shown here, the LED die  287  is connected on the opposite side of the leadframes  271  and  272  in such a manner as to oppose the LED die  286 . The LED device  270  is mounted, with the bottom side of  FIG. 20(   b ) facing down, on a mother substrate in the same manner as the LED device  200  shown in  FIG. 16 . 
         [0141]      FIG. 21  is a circuit diagram of the LED device  270 . 
         [0142]    As shown, the LED dies  284 ,  285 ,  286 , and  287  are connected in parallel. The anode and cathode of the parallel circuit shown in  FIG. 21  respectively correspond to the leadframes  271  and  272 . 
         [0143]    The positional relationship between the large-sized leadframe  251  and the LED dies  284  and  286  will be described with reference to  FIG. 18 . As earlier described for the LED  200 ,  FIG. 18  is a top plan view showing a portion of the large-sized leadframe  251  as viewed from the top by removing the adhesive sheet  252  in  FIG. 17(   d ). The LED dies  284  and  286  are arranged in a lattice pattern in such a manner as to straddle the gap between the copper plates. The LED device  270  is obtained by cutting the portion indicated by G from the large-sized leadframe  251  after the covering. That is, the fabrication process for the LED device  270  is the same as that for the LED device  200  up to the step of covering the structure with the covering member, but differs in the way the LED device is cut from the large-sized leadframe  251 . 
       Seventh Embodiment 
       [0144]    In the LED devices  200  and  270  described above, light is also emitted in a direction parallel to the leadframes  211  to  213  or the leadframes  271  and  272 . Depending on the application of the LED devices  200  and  270 , this emitted light may not only be difficult to utilize but also pose a problem. For example, in the LED device  200 , the distance that the light emitted in the direction vertical to the leadframes  211  to  213  travels through the covering member  214  may differ from the distance that the light emitted in the horizontal direction travels through the covering member  214 . In that case, the amount of wavelength conversion that the light undergoes while passing through the phosphors is different; as a result, the color of the emitted light may be different depending on the direction in which it is emitted. In view of this, the following description deals with an LED device (semiconductor light emitting device)  300  which does not emit light in the direction parallel to the leadframes but emits light only in the direction vertical to the leadframes. In the LED device  300 , the same component elements as those of the LED device  200  are designated by the same reference numerals. 
         [0145]      FIG. 22  is a diagram showing the external appearance of the LED device  300 : part (a) is a top plan view, (b) is a front view, and (c) is a right side view. 
         [0146]    When the LED device  30  is viewed from the top, phosphor sheets  301  and  303  and a reflective member  302  sandwiched between the phosphor sheets  301  and  303  are seen in addition to the leadframes  211 ,  212 , and  213  extending horizontally in the reflective member  302  (see  FIG. 22(   a )). The leadframes  211 ,  212 , and  212  and  213  are arranged one adjacent another with their end portions in close proximity to each other. The left side edge of the leadframe  211  and the right side edge of the leadframe  213  are respectively flush with the left and right side edges of the phosphor sheets  301  and  303  and the reflective member  302 . When the LED device  300  is viewed from the front, only the phosphor sheet  303  is seen (see  FIG. 22(   b )). When the LED device  300  is viewed from the right side, the phosphor sheets  301  and  303  and the reflective member  302  sandwiched between the phosphor sheets  301  and  303  are seen in addition to the leadframe  213  embedded in the reflective member  302  (see  FIG. 22(   c )). Though not shown here, the bottom view of the LED device  300  is the same as the top plan view of  FIG. 22(   a ). The left side view of the LED device  300  is similar to the right side view of  FIG. 22(   c ), except that the leadframe  211  is seen in place of the leadframe  213 . 
         [0147]      FIG. 23  is a cross-sectional view taken along line II′ in  FIG. 22(   b ). 
         [0148]    The LED device  300  includes the leadframes  211 ,  212 , and  213 , reflective member  302 , phosphor sheets  301  and  303 , and LED dies  215  to  218 . In the LED device  300 , as in the LED device  200  (see  FIG. 14 ), the LED dies  215  and  216  are each flip-chip mounted on the front surfaces of two of the leadframes  211  to  213  in such a manner as to straddle the gap  219 . Similarly, the LED dies  217  and  218  are each flip-chip mounted on the back surfaces of the leadframes  211  to  213  in such a manner as to straddle the gap  219 . The leadframes  211  to  213  and the LED dies  215  to  218  are the same between the LED device  300  and the LED device  200 . The surface treatment of the leadframes  211  to  213  and the connecting structure connecting the LED dies  215  to  218  to the leadframes  211  to  213  are also the same between the LED device  300  and the LED device  200 . 
         [0149]    In the LED device  300 , the bottom and side faces of the LED dies  215  to  218  are covered with the reflective member  302 , while the top faces of the LED dies  215  to  218  are covered with the respective phosphor sheets  301  and  303 . That is, in the LED device  300 , the reflective member  302  and the phosphor sheets  301  and  303  together constitute the covering member. The reflective member  302  is formed by mixing fine reflective particles such as titanium oxide or alumina into a binder such as a silicone resin or organopolysiloxane, kneading the mixture, and curing the mixture. The phosphor sheets  301  and  303  are each formed by mixing phosphors into a silicone resin, kneading the mixture, and curing the mixture. The phosphor sheets  301  and  303  are bonded to the reflective member  302  and the top faces of the LED dies  215  to  218  by a transparent adhesive (not shown). 
         [0150]      FIG. 24  is a diagram for explaining a fabrication method for the LED device  300 . 
         [0151]    The fabrication method of the LED device  300  employs the same steps as the step of preparing the large-sized leadframe (see  FIG. 17(   a )), the step of placing the LED dies on the bonding sheets (see  FIGS. 17(   b ) and  17 ( c )), and the step of connecting the LED dies to the large-sized leadframe (see  FIG. 17(   d )) shown in the fabrication method of the LED device  200 , and therefore, the description of these steps will not be repeated here. 
         [0152]      FIG. 24(   a ) is the same diagram as that shown in  FIG. 17(   d ), and shows the starting step (initial condition) of the process that characterizes the fabrication method of the LED device  300 . 
         [0153]    From the condition shown in  FIG. 24(   a ), only the adhesive sheet  252  is removed (see  FIG. 24(   b )).  FIGS. 24(   b ),  24 ( c ), and  24 ( d ) show the step for covering the LED dies  215  to  218  with a reflective member  322  and phosphor sheets  321  and  323 . 
         [0154]    Next, the reflective member  322  before curing is filled into the space between the LED dies  215  to  218  to cover the bottom and side faces of the LED dies  215  to  218  (see  FIG. 24(   c )). After filling, the reflective member 322 is cured at about 150° C. The reflective member  322  can be applied using a squeegee, and the portions of the reflective member  322  that remain on the top faces of the LED dies  215  and  216  after curing are removed by polishing. Alternatively, the reflective member  322  whose amount is accurately measured using a dispenser may be applied. In that case, there is no need to polish the top faces of the LED dies  215  and  216 . 
         [0155]    Next, the top faces of the LED dies  215  to  218  are covered with the respective phosphor sheets  321  and  323  (see  FIG. 24(   d )). A transparent adhesive material is applied over the top faces of the LED dies  215  and  216  as well as the upper surface of the reflective member  322 , and the phosphor sheet  321  is bonded. In parallel with this step, the adhesive sheet  253  is removed, a transparent adhesive material is applied over the top faces (the lower faces in the figure) of the LED dies  217  and  218  as well as the surface of the reflective member  322 , and the phosphor sheet  323  is bonded. Instead of forming the phosphor sheets  321  and  323 , a fluorescent resin prepared by mixing phosphors into a transparent binder such as silicone may be applied over the top faces of the LED dies  215  to  218  as well as the surfaces of the reflective member  322 , the resin then being cured to form phosphor layers. In this case, the phosphor layers are used as the fluorescent members for covering the top faces of the LED dies  215  to  218 . However, when the phosphor sheets  321  and  323  are used as the fluorescent members as in the LED device  300 , the advantage is that the covering step can be accomplished in a short time, because the covering by the reflecting member  322  can be performed concurrently with the preparation of the phosphor sheets  321  and  323 . 
         [0156]    Finally, the large-sized leadframe  251  covered as described above is diced into individual LED devices  300  (see  FIG. 24(   e )).  FIG. 24  (e) shows the same step as that of  FIG. 17(   f ), except that the covering member used is different. 
         [0157]    In the LED devices  200 ,  270 , and  300  described above, the forward voltage drop must be made equal for all the four LED dies  215  to  218  or  284  to  287 . For example, in the fabrication process, the difference in forward voltage drop must be held to within 0.1 V. That is, in the fabrication process, after dicing the wafer containing a large number of LED dies, the LED dies are sorted out according to the forward voltage drop. If the LED dies are arranged with a prescribed pitch and orientation on the respective adhesive sheets  252  and  253  while sorting out the LED dies, the pickup job can be standardized, and the fabrication process can be shortened. 
         [0158]    In the LED devices  200 ,  270 , and  300  described above, the cut faces of the leadframes  211  and  213  or the leadframes  271  and  272  are made flush with the cut faces of the covering member  214  or  273  (the reflective member  302  in the case of the LED device  300 ). When mounting the LED device  200 ,  270 , or  300  on a mother substrate, if the connection strength is not sufficient, the end portions of the leadframes  211  and  213  or the leadframes  271  and  272  may be made to protrude from the respective cut faces of the covering member  214  or  273  (the reflective member  302  in the case of the LED device  300 ). For example, in  FIG. 13(   a ), the leadframes  211  and  213  may be made to extend horizontally. In this case, the outwardly protruding portions of the leadframes  211  and  213  or the leadframes  271  and  272  may be bent to conform to the side faces of the LED device  200 ,  270 , or  300 . 
         [0159]    In the LED device  300 , the side faces of the LED dies  215  to  218  are covered with the reflective member  302 , and the phosphor sheets  301  and  303  are bonded to the upper and lower surfaces of the reflective member  302  as well as to the top faces of the respective LED dies  215  to  218  (see  FIG. 23 ). However, if the light is to be emitted only in the direction vertical to the leadframes  211  to  213 , the reflective member may be provided not only on the side faces of the LED dies to which the fluorescent members are laminated but also on the side faces of the fluorescent members laminated to the top faces of the respective LED dies. To fabricate such an LED device, a phosphor layer is formed in advance on the sapphire substrate at the wafer level, and then the wafer is diced into individual LED dies each covered with the phosphor layer; when such LED dies are obtained, a batch fabrication method is applied that uses two adhesive sheets and a large-sized leadframe, as illustrated in connection with the fabrication method for the LED device  200 . That is, after mounting the LED dies on both sides of the large-sized leadframe, the reflective member is filled into the space surrounding the respective LED dies, and finally, the large-sized leadframe is cut apart. It is preferable that the binder to be used in the phosphor layer is selected from among transparent inorganic materials such as glass that can withstand the temperature applied when joining the LED dies to the large-sized leadframe.