Self assembly based 3D heatsink antenna for high density 3D integration

Abstract

Heatsinks are typically designed near the power amplifier in a wireless transmission circuit. The radiations from heatsinks are undesirable to the nearby antenna component and should be minimized to reduce electromagnetic interference (EMI). However, in certain applications the heatsink components are in the circuit is unavoidable. The use of heatsink as a transmitting or receiving electromagnetic radiation will be of significant value if heatsink is designed as an antenna, instead of having two separate components: antenna and heatsink. This paper investigates the radiation property of heatsinks as an antenna at two different frequencies: low (2.4 GHz) and high (24 GHz) frequencies. The fabrication of heatsink antennas depend on the designed resonant frequency. As the antennas are made smaller, their resonant frequency increases. Building millimeter-wave capable antennas via conventional semiconductor processing techniques becomes feasible. The fabrication of high frequency on-chip 3D heatsink antennas can be visualized using a novel self assembly process. The self assembly (SA) technique is driven by surface tension property to pull 2D metal patterns into 3D structures. The SA method involves conventional semiconductor steps with an additional dip soldering and reflow steps to develop 3D heatsinks. The 3D heatsink shows improved antenna properties at low and high frequencies.