I. Introduction
There is growing interest in the use of additive manufacturing (AM) for rapid prototyping of millimeter wave circuits (mmWave). Millimeter wave circuits are composed of many semiconductor technologies, and an approach that allows heterogeneous integration of many components within a small footprint is desired to meet the challenge of the next generation of systems such as compact light weight radars. Four chip integration techniques using AM that have recently been demonstrated for RF applications are: (i) chip in pocket [1], (ii) embedded devices [2]; (iii) chip on board with interconnect ramp [3] and (iv) chip first [4]. These techniques allow the assembly of many devices within a small working area with low interconnect losses. Among all these, the chip in pocket technique is attractive as it takes advantage of conventional lithographic fabrication for large area fabrication and AM for critical interconnects and transition regions at the chip-board interface, while allowing good thermal interface to the substrate.