Carbon nanotube heatsink

Fujitsu has developed a carbon nanotube-based package for semiconductor devices that it plans to use to enhance the performance of high frequency amplifiers.

In wireless communication systems, there is an increasing demand for higher power and higher frequencies in amplifiers used in mobile phone base stations. And because the high power transistors used in the amplifiers generate high levels of heat, heat dissipation is extremely important.

Conventionally, heat was dissipated through the use of what is known as a “face-up structure”, in which a high power transistor device would be connected directly dice-bonded to the package.

At higher frequencies, amplifiers using the face-up structure suffer from reduced amplification due to an increase in inductance from the metal wire through which the electrical current flows from the chip to the package.

One solution is to flip over the chip and connect the chip and the package with short metallic bumps made from gold or other metals in a “flip-chip structure”.