In U.S. Patent Application 20090297801, Samsung Electro-Mechanics Co., LTD researchers Seung Hyun Cho, Byoung Youl Min, Soon Jin Cho and Jin Won Choi disclose how to manufacture a heat radiation substrate with a metal core using carbon nanotubes for computer chips. The manufacturing method includes injection-molding mixed powder of carbon nanotubes and metal in a die to fabricate a metal core having through holes., That is followed by molding the entire metal core including the through holes with an insulating resin to fabricate a metal core substrate; then processing the insulating resin in the through holes to form connection holes; and forming a circuit pattern on the metal core substrate in which the connection holes are formed. The amount of the carbon nanotubes in the mixed powder is 20% by weight or less.
When carbon nanotubes are used to manufacture a heat radiation substrate, since the area of the heat radiation substrate is larger than that of a chip, which is a heating element, the temperature of the chip is greatly decreased, so that, in a package system, the size and capacity of a cooling system including a cooling fan and a radiation fin are decreased, or the cooling system is not required, thereby decreasing the manufacturing cost of the heat radiation substrate.
As shown in FIGS. 1A to 1C, carbon nanotubes, which are materials having carbon chains, such as a single-walled nanotube structure (see FIG. 1A), a multi-walled nanotube structure (see FIG. 1B), and a nanotube rope structure, have a thermal conductivity of about 3000.about.6000 W/mK. Carbon nanotubes have very high radiation performance, considering that the thermal conductivities of copper and aluminum, which are used as materials having excellent thermal conductivity, are 350 W/mK and 210 W/mK, respectively. In particular, carbon nanotubes are very useful in the dissipation of heat from a small area such as in a chip because the chain structure thereof determines the direction of heat transfer therethrough.
FIG. 5 is a schematic sectional view showing a multi-layered heat radiation substrate including the metal. Insulating resin layers 208 and 308 are layered on the substrate, on which the circuit layer is formed, through a general build-up process, and circuit patterns 211 and 311 are formed on the respective insulating resin layers 208 and 308 through a circuit forming process, thus further forming at least one outer circuit layer. Moreover, a solder resist layer 401 may be formed on the outermost circuit layer (see FIG. 5), and then the solder resist layer 401 may be surface-treated using a commonly used solder resist opening process and a nickel/gold plating process.
FIGS. 6A to 6c are views explaining a general radiation method of a substrate.
