Abstract:
A compound semiconductor device package module structure includes a heat dissipation film, a dielectric layer, a plurality of compound semiconductor dies, means for mounting the compound semiconductor dies on the heat dissipation film, and a transparent encapsulation material. The dielectric layer includes a plurality of openings formed on the heat dissipation film. The compound semiconductor dies are placed on the heat dissipation film in the openings, and adjacent two compound semiconductor dies are separated by the dielectric layer. The transparent encapsulation material covers the compound semiconductor dies.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    (A) Field of the Invention 
         [0002]    The present invention relates to a package module structure of compound semiconductor devices and fabricating method thereof, and more particularly, to a thin package module structure for a photoelectric semiconductor device and fabricating method thereof. 
         [0003]    (B) Description of the Related Art 
         [0004]    Because the light emitting diode (LED) pertaining to the photoelectric device has advantages of a small body, high efficiency and long lifetime, it is deemed as an excellent illuminant source for the next generation. Furthermore, LCD (liquid crystal display) technology is developing rapidly and full color is the current trend in electronic product displays. Therefore, the white series LEDs are not only applicable to indication lights and large size display screens but also to most consumer electronics products such as mobile phones and personal digital assistants (PDA). 
         [0005]      FIG. 1  is a schematic cross-sectional diagram of the conventional SMD (surface mount device) of an LED device. An LED die  12  is mounted on an N-type conductive copper foil  13   b  covering an insulation layer  13   c  through die bonding paste  11 , and is electrically connected to a P-type conductive copper foil  13   a  and the N-type conductive copper foil  13   b  through metal wires  15 . The assembly of the P-type conductive copper foil  13   a,  N-type conductive copper foil  13   b  and insulation layer  13   c  form a substrate  13  with circuit pattern. Furthermore, a transparent encapsulation material  14  covers the substrate  13 , metal wires  15  and die  12  so that the whole LED device  10  can be protected against damage from environmental and external forces. 
         [0006]    The LED device  10  utilizes a common printed circuit board (PCB) as the substrate  13 . The total thickness of the LED device  10  is limited by the insulation layer  13   c  of the substrate  13 ; hence it cannot be reduced further. However, the current trend of consumer electronics products is towards a light, thin, short and small body. Accordingly, each of the internal devices of the consumer electronics product and its shell needs to be miniaturized. In addition, the insulation layer  13   c  is made mostly of epoxy resin with poor heat dissipation, and therefore is not suitable for a high power chemical compound semiconductor device as a heat-transferring path. If plural LED devices  10  constitute an LED module, a more serious heat dissipation problem may occur. 
         [0007]    In view of the above, the consumer electronics market is in urgent need of a thin type package module structure of compound semiconductor device. The device not only needs to have a reduced thickness for saving space, but also needs to address the heat dissipation problem. With such a device, reliable, high power electronics products can be more easily manufactured. 
       SUMMARY OF THE INVENTION 
       [0008]    One aspect of the present invention provides a package module structure of compound semiconductor devices and a fabricating method thereof. The package module structure of compound semiconductor devices has a heat dissipation film for effectively dissipating heat, so as to resolve the poor heat dissipation problem. Moreover, by using a thin substrate, the package module structure of compound semiconductor devices can be made thinner for saving space. 
         [0009]    In accordance with the present invention, a package module structure of compound semiconductor devices includes a heat dissipation film, a dielectric layer, a plurality of compound semiconductor dies, means for mounting the compound semiconductor dies on the heat dissipation film, and a transparent encapsulation material. The dielectric layer includes a plurality of openings and is formed on the heat dissipating film. The plurality of compound semiconductor dies are formed on the heat dissipation film in the openings of the dielectric layer, and adjacent pairs of compound semiconductor dies are separated by the dielectric layer. The transparent encapsulation material overlays the compound semiconductor dies. 
         [0010]    In an embodiment, a package module structure of compound semiconductor devices further includes a circuit board (e.g., a flexible printed circuit). The circuit board includes a first electrode and a second electrode disposed on the dielectric layer at two sides of the compound semiconductor die. Means for mounting the compound semiconductor dies on the heat dissipation film include die bonding paste connecting the compound semiconductor dies and the heat dissipation film and wires connecting the compound semiconductor dies to the first electrode and the second electrode. In an embodiment, the thickness of the package module structure of compound semiconductor devices may be between 0.4 and 0.8 mm. 
         [0011]    In accordance with another embodiment of the present invention, the heat dissipation film is an electrically conductive film with a circuit pattern. The electrically conductive film has a first electrode and a second electrode disposed at two sides of the compound semiconductor die. Means for mounting the compound semiconductor dies on the heat dissipation film include flip chip bonding connecting the compound semiconductor die to the first electrode and the second electrode of the electrically conductive film. A plurality of bumps may electrically connect the compound semiconductor dies to the first electrode and the second electrode of the electrically conductive film. In this embodiment, the thickness of the package module structure may be between 0.15 and 0.3 mm 
         [0012]    In accordance with a first embodiment, a method for fabricating a package module structure of compound semiconductor devices includes the steps of: providing a heat dissipation film; forming a dielectric layer on the heat dissipation film, the dielectric layer comprising a plurality of openings; mounting a plurality of compound semiconductor dies on the heat dissipation film in the openings; forming a circuit board on the dielectric layer, the circuit board comprising a first electrode and a second electrode disposed on the dielectric layer at two sides of the compound semiconductor die; electrically connecting the plurality of compound semiconductor dies to the first electrode and the second electrode; and overlaying a transparent encapsulation material on the compound semiconductor dies. In an embodiment, the plurality of compound semiconductor dies, the first electrode and the second electrode are electrically connected by wire bonding using metal wires. 
         [0013]    In accordance with a second embodiment, a method for fabricating a package module structure of compound semiconductor devices includes the steps of: providing a heat dissipation film having a first electrode and a second electrode; forming a dielectric layer on the heat dissipation film, the dielectric layer comprising a plurality of openings; mounting a plurality of compound semiconductor dies on the heat dissipation film in the openings and electrically connecting the compound semiconductor dies to the first electrode and the second electrode; and overlaying a transparent encapsulation material on the compound semiconductor dies. In an embodiment, the step of mounting a plurality of compound semiconductor dies on the heat dissipation film in the openings is performed by flip chip bonding and electrically connecting the compound semiconductor dies to the first electrode and the second electrode through a plurality of bumps. 
         [0014]    In practice, the package module structure of compound semiconductor devices may be formed on a temporary substrate, and then the temporary substrate is removed after the compound semiconductor dies are covered with the transparent encapsulation material. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    The objectives and advantages of the present invention will become apparent upon reading the following description and upon reference to the accompanying drawings in which: 
           [0016]      FIG. 1  is a schematic cross sectional diagram of the conventional SMD (surface mount device) of an LED device; 
           [0017]      FIGS. 2A through 2H  show the manufacturing steps of the package module structure of compound semiconductor devices in accordance with a first embodiment of the present invention; and 
           [0018]      FIGS. 3A through 3E  show the manufacturing steps of the package module structure of compound semiconductor devices in accordance with a second embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0019]      FIGS. 2A through 2H  are schematic illustrations showing the manufacturing steps of the package module structure of compound semiconductor devices in accordance with a first embodiment of the present invention.  FIG. 2A  shows a circuit board  21  with holes  22 . In an embodiment, the circuit board  21  is a flexible printed circuit (FPC), e.g., FR-4, and is prepared in advance as a component for sequentially fabricating the package module structure of compound semiconductor devices. 
         [0020]    In  FIG. 2B , a temporary substrate  23  includes a first surface  231  and a second surface  232 . In this drawing, the first surface  231  is an upper surface and the second surface  232  is a lower surface. The temporary substrate  23  may be made of a metallic material, a ceramic material or a polymer material. A heat dissipation film  24  is formed on the first surface  231  of the temporary substrate  23 . The heat dissipation film  24  may be a metallic film without a circuit pattern and may be made of silver, nickel, copper, tin, aluminum or an alloy of the aforesaid metallic materials. Furthermore, conductive transparent materials such as indium tin oxide (ITO), indium zinc oxide (IZO), indium gallium oxide (IGO) and indium tungsten oxide (IWO) also are suitable for the material of heat dissipation film  24 . 
         [0021]    In  FIG. 2C , dielectric layers  26  are formed on the heat dissipation film  24  by molding or injection, and an opening  27  is formed between every two dielectric layers  26 . The openings  27  are structures of reflective cups, and their positions correspond to those of the holes  22  of the circuit board  21 . 
         [0022]    In  FIG. 2D , compound semiconductor dies  29  are mounted on the heat dissipation film  24  in the openings  27  through a die bonding paste  28 , and then the circuit board  21  is put on dielectric layers  26 . The holes  22  of the circuit board  21  correspond to the openings  27 , as shown in  FIG. 2E . In this embodiment, the circuit board  21  at the two sides of the opening  27  is provided with an N-type electrode  211  and a P-type electrode  212 . In an embodiment, the dies  29  may be LEDs, laser diodes, photo sensors, or photocells. 
         [0023]    In  FIG. 2F , through wire-bonding technologies, metal wires  30  are used for electrically connecting the dies  29 , the N-type electrode  211  and the P-type electrode  212 . 
         [0024]    In  FIG. 2G , a transparent encapsulation material  31  such as epoxy resin and silicone is overlaid on the dies  29 , the N-type electrode  211 , the P-type electrode  212 , and the metal wires  30 . The transparent encapsulation material  31  is further mixed with fluorescent powders so that a secondary light can be emitted from the excited fluorescent powders. The secondary light is mixed with a primary light emitted from the dies  29  to form a white light or electromagnetic radiation waves with multiple wavelengths. The material of the mixed fluorescent powders may be YAG, TAG, silicate, or nitride-based fluorescent powders. The transparent encapsulation material  31  may be formed by transfer-molding or injection molding. 
         [0025]    After the transparent encapsulation material  31  is hardened, the temporary substrate  23  is removed by bending, separating, etching, laser cutting or grinding. Therefore, a first surface  241  of the heat dissipation film  24  is exposed, and accordingly the package module structure  20  of the compound semiconductor device is completed as shown in  FIG. 2H . The first surface  241  of the heat dissipation film  24  is opposite to a second surface  242 , and the second surface  242  is still covered by the transparent encapsulation material  31 . 
         [0026]    Because the N-type electrode  211  and the P-type electrode  212  at two ends of the package module structure  20  are not covered by the transparent encapsulation material  31 , they can serve as outer contacts for surface mounting. Furthermore, the heat generated from the dies  29  is directly transferred by the heat dissipation film  24  with a superior conductive coefficient so that the heat dissipation efficiency of the package module structure  20  is significantly improved. Compared with prior arts, the thickness of the package module structure  20  can be reduced to 0.3-1.0 mm, and the package module structure  20  can be viewed as a super-thin structure. 
         [0027]      FIGS. 3A through 3E  are schematic illustrations showing the manufacturing steps of the package module structure of compound semiconductor devices in accordance with a second embodiment of the present invention, in which flip chip technology is employed. 
         [0028]    In  FIG. 3A , a temporary substrate  43  includes a first surface  431  and a second surface  432 . In this drawing, the first surface  431  is an upper surface and the second surface  432  is a lower surface. The temporary substrate  43  may be made of a metallic material, a ceramic material or a polymer material. A heat dissipation film  44  with a pattern is formed on the first surface  431  through printing, screening, electroform, chemical plating (or electroless plating) or sputtering. In this embodiment, the heat dissipation film  44  is an electrically conductive film including an N-type electrode  441  and a P-type electrode  442 , which are disposed at two sides of each isolation gap  70  to form required circuits of the package module structure. The electrically conductive film may be made of silver, nickel, copper, tin, aluminum or an alloy of the aforesaid metallic materials. Furthermore, conductive transparent materials such as indium tin oxide (ITO), indium zinc oxide (IZO), indium gallium oxide (IGO) and indium tungsten oxide (IWO) also are suitable for the material of the heat dissipation film  44 . 
         [0029]    In  FIG. 3B , dielectric layers  46  are formed on the heat dissipation film  44  by molding or injection, and an opening  47  is formed between every two dielectric layers  46 . The openings  47  correspond to the isolation gaps  70  of the heat dissipation film  44 . 
         [0030]    In  FIG. 3C , the dies  49  are mounted on the heat dissipation film  44  through flip chip bonding, in which plural bumps  48  electrically connect the dies  49 , the N-type electrode  441 , and the P-type electrode  442 . 
         [0031]    In  FIG. 3D , a transparent encapsulation material  50  such as epoxy resin and silicone is formed in the openings  47 , by which the transparent encapsulation material  50  is overlaid on the dies  49 , the N-type electrode  441 , and the P-type electrode  442 . The transparent encapsulation material  50  may be overlaid on the dies  49  by transfer-molding or injection molding. 
         [0032]    After the transparent encapsulation material  50  is hardened, the temporary substrate  43  is removed by bending, separating, etching, laser cutting or grinding, so that a first surface  443  of the heat dissipation film  44  is exposed. Accordingly, the package module structure  40  of the compound semiconductor device is completed, as shown in  FIG. 3E . The first surface  443  of the heat dissipation film  44  is opposite to a second surface  444 , and the second surface  444  is still covered by the transparent encapsulation material  50 . 
         [0033]    Because the N-type electrode  441  and the P-type electrode  442  of the package module structure  40  of the compound semiconductor device are not covered by the transparent encapsulation material  50 , they can serve as outer contacts for surface mounting. Furthermore, the heat generated from the dies  49  is directly transferred by the heat dissipation film  44  with a superior conductive coefficient so that the heat dissipation efficiency of the package module structure  40  is improved. 
         [0034]    The process sequence is not restricted for the above embodiments, but should comply with the module process from a high temperature to a low temperature. 
         [0035]    The flip chip technology is employed for the second embodiment, and in comparison with the first embodiment, the thickness of the package module structure  40  generally can be further decreased to 0.1-0.6 mm. The package module structures  20  and  40  can be light bars or light plates as desired, thereby providing various applications. 
         [0036]    In comparison with prior arts, in addition to being applied to thin structures, the entire lower surface of the package module structures  20  and  40  is a heat dissipation film that can effectively dissipate heat generated by the compound semiconductor devices, so as to increase heat dissipation efficiency. Accordingly, brightness, thermal stability and lifetime of the compound semiconductor devices can be increased. Further, the use of FPC provides flexibility, and can be applied for the backend module with a bending surface. 
         [0037]    The above-described embodiments of the present invention are intended to be illustrative only. Those skilled in the art may devise numerous alternative embodiments without departing from the scope of the following claims.