Abstract:
The present invention relates to an electronic component assembly including a composite material carrier, a circuit carrier made of a dielectric material, a circuit with a conductive material formed on the circuit carrier, an intermediate layer between the circuit carrier and the composite material carrier, and an electronic component arranged on the composite material carrier and electrically connecting to the circuit.

Description:
TECHNICAL FIELD 
       [0001]    The invention relates to an electronic component assembly, and more particularly to an electronic component assembly having a composite material carrier. 
       REFERENCE TO RELATED APPLICATION 
       [0002]    This application claims the right of priority based on TW application Ser. No. 096112292, filed Apr. 4, 2007, and the content of which is hereby incorporated by reference. 
       DESCRIPTION OF BACKGROUND ART 
       [0003]    With the popularity of light-emitting diodes (LEDs), the variety of sizes of bare chips provided by manufacturers also grows. When the size of a bare chip increases, the light output uplifts under a constant current density. However, the heat imposed on the chip also climbs with the increase of input current. 
         [0004]    A conventional LED lamp of 5 mm package size has a thermal resistance in the range of 250□/W˜300 □/W. Provided a high power chip is packaged in a conventional configuration, owing to poor heat dissipation, the surface temperature of the chip is expected to rise rapidly, and the surrounding epoxy is carbonized and discolored. Accordingly, the decay of the chip radiation performance is accelerated till failed. Furthermore, a thermal expansion stress due to a sharp temperature change possibly causes damage to the package structure. 
         [0005]    Up to now, the high power LED is generally packaged by forming an insulating material, e.g. epoxy, oxide, and nitride, on a metallic substrate, e.g. Al, and Cu. However, the metallic substrate usually has a thermal expansion coefficient (CTE) greatly different from that of the insulating material. For example, the CTE of Al is about 2.3×10 −5 /□, and the CTE of epoxy is about 5˜6×10 −5 /□. The CTE of an LED epitaxial material is usually smaller than 1×10 −5 /□, or in the range of 4˜8×10 −6 /□. For example, the CTE of Al 2 O 3  or AlN is about 4˜8×10 −6 /□. At an operation temperature higher than 60□, the chip easily splits at the interface with the metallic substrate due to the thermal expansion coefficient difference between those materials. 
         [0006]    Moreover, the heat crowding in the high-current-driven chip also deteriorates the light output performance of an LED. The silver paste used to fasten the chip has a lower thermal conductivity, and therefore cannot provide a suitable thermal passage for heat transmitting to the metallic substrate. In consequence, the heat from the chip is easily crowded in some regions, which worsen the photoelectric characteristics and the reliability of the chip. 
       SUMMARY OF THE DISCLOSURE 
       [0007]    An electronic component assembly of present invention includes a composite material carrier; a circuit carrier made of a first dielectric material; a circuit formed on the circuit carrier and including a conductive material; an intermediate layer between the circuit carrier and the composite material carrier, and comprising at least one material selected from the group consisting of Ni, Ti, Cr, Al, W, Si, Mo, metal carbide, and the combination thereof; and an electronic component arranged on the composite material carrier and electrically connecting to the circuit. 
         [0008]    In one embodiment, the electronic component assembly further includes an outer layer covering an outer surface of the composite material carrier. The outer layer comprises at least one material selected form the group consisting of Ni, Ti, Cr, Cu, Au, Al, Pt, TiW, Pd, and Mo. 
         [0009]    In a preferable embodiment, the composite material carrier of the electronic component assembly is selected from the group consisting of metal matrix composite (MMC), polymer matrix composite (PMC), and ceramic matrix composite (CMC). 
         [0010]    The first dielectric material is selected from the group consisting of CaCO 3 , SiO 2 , Al 2 O 3 , MgO, Bi 2 O 3 , Tc, Pr, Po, Fr, Ra, BeO, B 2 O 3 , Li 2 O, ZnO, WS 2 , RuO 2 ,SnO 2 , LaB 6 , In 2 O 3 , Ta 2 N, BaTiO 3 , CuO, CdO, and Ta 2 O 5 . 
         [0011]    The conductive material is selected from the group consisting of Au, Ag, Al, Cu, W, Ni, Pd, and Pt. 
         [0012]    The electronic component is selected from the group consisting of light-emitting diode, laser diode, transistor, integrated circuit, and solar cell. Specifically, the electronic component includes an n-type semiconductor layer; a p-type semiconductor layer; and a light-emitting layer between the n-type semiconductor layer and the p-type semiconductor layer. 
         [0013]    In embodiments, the composite material carrier has a thermal expansion coefficient not greater than 1.2×10 −5 /□. The composite material carrier has a thermal conductivity not less than 150 W/m° K. The thermal expansion coefficient difference between the composite material carrier and the electronic component is not greater than 1×10 −5 /□. 
         [0014]    The composite material carrier comprises at least one material selected from the group consisting of carbon fiber, carbon particulate, carbon flake, carbon laminate, carbon nanotube, diamond, diamond-like carbon, and graphite. 
         [0015]    In further embodiment, the electronic component is positioned on the composite material carrier in a flip-chip configuration. 
         [0016]    In another embodiment, the electronic component assembly further includes a connecting means for connecting the composite material carrier and the electronic component, wherein the connecting means is selected from the group consisting of screwing, snap fitting, friction fitting, glue bonding, eutectic bonding, ultrasonic bonding, pressure bonding, and surface active bonding. 
         [0017]    The connecting means optionally includes a bonding layer comprising at least one material selected from the group consisting of, Benzocyclobutene (BCB), epoxy, polyimide, SOG, silicone, solder, Au, Ag, Al, Cu, Ni, Pd, Pt, CaCO 3 , SiO 2 , Al 2 O 3 , MgO, Bi 2 O 3 , Tc, BeO, B 2 O 3 , Li 2 O, RuO 2 , SnO 2 , LaB 6 , In 2 O 3 , Ta 2 N, BaTiO 3 , CuO, CdO, and Ta 2 O 5 . 
         [0018]    In another embodiment, the circuit carrier of the electronic component assembly further includes a second dielectric material. The dielectric material is selected from the group consisting of CaCO 3 , SiO 2 , Al 2 O 3 , MgO, Bi 2 O 3 , Tc, Tr, Po, Fr, Ra, BeO, B 2 O 3 , Li 2 O, ZnO, WS 2 , RuO 2 , Bi 2 Ru 2 O 7 , PbRu 2 O 6 , IrO 2 , SnO 2 , LaB 6 , In 2 O &#39; , Ta 2 N, BaTiO 3 , CuO, CdO, and Ta 2 O 5 . 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0019]      FIG. 1  illustrates an electronic component assembly in accordance with an embodiment of present invention. 
           [0020]      FIG. 2  illustrates an electronic component assembly in accordance with another embodiment of present invention. 
           [0021]      FIG. 3  illustrates an electronic component assembly in accordance with a further embodiment of present invention. 
           [0022]      FIGS. 4A and 4B  illustrate electronic component assemblies in accordance with another embodiments of present invention. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0023]    The embodiments of the invention are described in accompany with drawings. 
         [0024]    The notations in  FIG. 1  represent as follows,  10  is an electronic component assembly;  11  is a composite material carrier;  13  is an intermediate layer;  14  is a circuit carrier;  15  is a circuit;  16  is a wiring;  17  is an electronic component;  18  is a connecting means. The same elements in other drawings are represented by the same notations and no description is further directed to. 
         [0025]    As shown in  FIG. 1 , the composite material carrier  11  and the circuit carrier  14  are connected via the intermediate layer  13 . The circuit  15  is formed on the circuit carrier  14 . The electronic component  17  is mounted on the composite material carrier  11  through the connecting means  18 . The connecting means  18  includes, but not limited to, screwing, snap fitting, friction fitting, glue bonding, eutectic bonding, thermal bonding, ultrasonic bonding, pressure bonding, surface active bonding, and the combination thereof. The electronic component  17  can be electrically connected to the circuit  15  through the wiring  16 , in flip-chip configuration, or other method for transmitting current and/or signal. 
         [0026]    The composite material is made from two or more materials, and the two or more materials are not integrated into another type of molecular or atomic structure. The composite material can have superior physical or chemical properties, for example, the composite material is lighter, stronger, and has a better thermal property. The composite material can be generally categorized into metal matrix composite (MMC), polymer matrix composite (PMC), and ceramic matrix composite (CMC), which are manufactured by mixing carbon fiber or glass fiber with metal, polymer, and ceramics respectively. 
         [0027]    In one embodiment, to transmit the massive heat from the electronic component  17 , one can choose a metal matrix composite with a thermal conductivity not smaller than 150 W/m° K. and a thermal expansion coefficient not smaller than 1.2×10 −5 /□, e.g. aluminum matrix composite (an available product in market is with a thermal conductivity of about 100˜640 W/m° K. and a thermal expansion coefficient of about 5˜15×10 −5 /□), as the composite material carrier  11 . However, the polymer matrix composite and the ceramic matrix composite can be adopted according to the requirement. 
         [0028]    In present invention, one material of the circuit carrier  14  is selected from CaCO 3 , SiO 2 , Al 2 O 3 , MgO, Bi 2 O 3 , Tc, Pr, Po, Fr, Ra, BeO, B 2 O 3 , Li 2 O, ZnO, WS 2 , RuO 2 , SnO 2 , LaB 6 , In 2 O 3 , Ta 2 N, BaTiO 3 , CuO, CdO, or Ta 2 O 5 . The Above materials all belong to ceramics. 
         [0029]    Besides aforementioned materials, the circuit carrier  14  can be also selected from a printed circuit board (PCB), a flexible printed circuit (FPC), or a semiconductor substrate such as Si substrate. If the semiconductor substrate is selected as the circuit carrier  14 , one may use various semiconductor manufacturing processes such as etching and sputtering to make the needed circuit, and may further integrate the semiconductor manufacturing processes with the procedure of making the electronic component. In addition, Si has suitable thermal properties (the thermal conductivity is about 150 W/m° K., and the thermal expansion coefficient is about 4×10 −6 /□). If a Si substrate is selected to integrate with the composite material carrier  11 , especially with the metal matrix composite carrier, due to the closeness of the thermal conductivity and the thermal expansion coefficient between the two materials, the thermal stress can be alleviated and the thermal conducting performance is enhanced. However, the printed circuit board and the flexible printed circuit are also candidates in response to the requirement. 
         [0030]    The circuit  15  can be selected from a printed circuit or a sintering ceramic circuit. The sintering ceramic circuit is made by metallic and ceramic materials. The metallic material is selected from Au, Ag, Al, Cu, W, Ni, Pd, Pt, or the combination thereof. The ceramic material is selected from CaCO 3 , SiO 2 , Al 2 O 3 , MgO, Bi 2 O 3 , Tc, Tr, Po, Fr, Ra, BeO, B 2 O 3 , Li 2 O, ZnO, WS 2 , RuO 2 , Bi 2 Ru 2 O 7 , PbRu 2 O 6 , IrO 2 , SnO 2 , LaB 6 . In 2 O 3 , Ta 2 N, BaTiO 3 , CuO, CdO, or Ta 2 O 5 . 
         [0031]    The intermediate layer  13  is selected from materials able to properly connect the composite material carrier  11  and the circuit carrier  14 . For metal matrix composite, the intermediate layer  13  is able to form a stable connection with both metal and carbon in the composite material. After evaluation, Ni, Ti, Cr, Al, W, Si, and Mo are expected to easily react with carbon to form metal carbide. 
         [0032]    The circuit carrier  14  and the composite material carrier  11  of present invention are connected via a connecting means  18 . The connecting means  18  can be an adhesive material, preferably, a soft adhesive material layer, more preferably, a soft adhesive material layer preserving an adhesive characteristic at room temperature, or middle to low temperature (for example, 500□-500□). The soft adhesive material is such as Benzocyclobutene (BCB ), epoxy, polyimide, SOG, silicone, solder, Au, Ag, Al, Cu, CaCO 3 , SiO 2 , Al 2 O 3 , MgO, Bi 2 O 3 , Tc, BeO, B 2 O 3 , Li 2 O, RuO 2 , SnO 2 , LaB 6 , In 2 O 3 , Ta 2 N, BaTiO 3 , CuO, CdO, Ta 2 O 5 , and the combination thereof. Provided the soft adhesive material can be solidified at a lower temperature (normally, below 300□), the thermal stress arose at high temperature between the composite material carrier  11  and the electronic component  17 , and between the composite material carrier  11  and the circuit carrier  14  can be alleviated, and the possible damage to the electronic component  17  at high temperature is decreased. 
         [0033]    Besides the soft adhesive material layer, a metal layer can be formed on the composite material carrier  11 , or on the composite material carrier  11  and the electronic component  17  respectively. A metallic solder layer such as AuSn is introduced between the metal layer and the electronic component  17  or between the two metal layers, and a eutectic bonding is implemented into the solder and the metal layer to connect the electronic component  17  like semiconductor light-emitting device and the composite material carrier. 
         [0034]    The electronic component  17  is mounted on the composite material carrier  11  and connected to the circuit  15  via wiring  16  or other electrical connecting means. In addition, the thermal expansion coefficient difference between the electronic component  17  and the composite material carrier  11  is not greater than 1×10 −5 /□, and therefore the thermal stress induced by the expansion of the electronic component  17  and the composite material carrier  11  is released. Furthermore, the composite material carrier  11  functions not only as the base of the assembly  10  but also as the heat dissipation medium of the electronic component  17 . 
         [0035]    The electronic component  17  is such as a light-emitting diode (LED), a laser diode (LD), a transistor, a VLSI, and a solar cell. The electronic component  17  in present embodiment is illustrated by a bare LED chip. The primary material of the bare LED chip has a thermal expansion coefficient in the range of 1×10 −6 □˜1×10 −5 /□, for example, the coefficients of GaN, InP, and GaP are 5.4×10 −6 □, 4.6×10 −6 /□, and 5.3×10 −6 □ respectively. In present embodiment, the composite material carrier  11  is selected as the carrier base of the assembly  10  to support the circuit carrier  14  and the electronic component  17 , and also functions as a heat dissipation medium, so as to match with the electronic component  17  in the thermal expansion coefficient level and prevent an unaffordable thermal stress from occurring in the connection of the electronic component  17  and the contact material. A well-chosen composite material carrier  11 , which has a thermal expansion coefficient different from that of the electronic component by 1×10 −5 /□ or less, can alleviate the influence of thermal stress. 
         [0036]    As shown is  FIG. 2 , in the drawing of an electronic component assembly  10  in accordance with another embodiment of present invention, notation  12  is directed to a smoothening layer, and the others are same as those depicted in  FIG. 1 . 
         [0037]    Provided the composite material carrier  11  has a rough surface, a smoothening layer  12  can be formed on whole or part of the outer surface of the composite material carrier  11  to fill in the rough surface of the composite material carrier  11 , and accordingly the electronic component  17  and the composite material carrier  11 , and/or the intermediate layer  13  and the composite material carrier  11  can be tightly integrated by the connecting means  18 . The material of the smoothening layer  12  is selected from Ni or other materials able to enhance the integration quality. 
         [0038]    As shown in  FIG. 3 , a connecting means  18  is optionally introduced between the electronic component  17  and the intermediate layer  13  on which the electronic component is mounted. As shown in  FIG. 4A , a connecting means  18  is optionally introduced between the electronic component  17  and the circuit carrier  14  on which the electronic component  17  is mounted. In  FIG. 4B , the electronic component  17  is disposed on the circuit  15  in a flip-chip configuration. 
         [0039]    The thick film process or the low temperature co-fired ceramics (LTCC) process can be adopted in the manufacture of the assembly of present invention. In a typical LTCC process, a mixture of ceramic powder, organic resin, solvent, and so forth undergoes a tape casting procedure, such that the ceramic material is formed as a green sheet. The wiring is made by printing a paste, which is a mixture of a metallic powder, such as Au, Ag, Cu, W, Ni, Pd, and Pt, and an organic vehicle, on the green sheet. After the co-fired and continued procedures, the LTCC process is complete. 
         [0040]    The foregoing description has been directed to the specific embodiments of this invention. It will be apparent; however, that other variations and modifications may be made to the embodiments without escaping the spirit and scope of the invention.