High-efficiency horn antenna using solder balls for seamless package with millimeter-wave 3D chips

This paper presents a millimeter-wave (mmWave) horn antenna to be inherently integrated with three-dimensional integrated circuits (3D ICs). Compared with conventional inpackage antennas which usually require separate chips or substrates, the designed horn efficiently uses the redundant metal solder balls between two chips/substrates. Therefore, this horn antenna neither occupies an alone chip nor increases the footprint of the 3D module. Different from substrate integrated waveguide horns, it also does not have dielectric filling inside, and subsequently features high efficiency (92%), high gain (~10dBi), as well as wide bandwidth (32GHz) at 135GHz. Moreover, this horn antenna uses a simple solder ball as its feeding to interconnect with ICs. This configuration significantly alleviates the high insertion loss between mmWave antenna and ICs, and realizes their packaging in a seamless way.