3D Heterogenous Integration Packaging of 5G RF Systems using Additive Electronics

The convergence of additive manufacturing and conventional electronic fabrication offers new opportunities for realizing compact and high performance radio frequency systems for 5G applications. Conventional subtractive fabrication provides great reliability, scalability and radio frequency performance but it is limited to planar geometries and struggles with dense 3D integration. This work presents a 3D heterogeneous integration approach that leverages the complementary strengths of conventional subtractive fabrication and additive manufacturing to address these limitations. Conventional printed circuit board fabrication was used to implement a control and an antenna subsystems. Additive manufacturing was employed to realize a 3D alumina board with embedded low noise amplifier chips. The alumina board incorporates pockets, vertical vias and radio frequency interconnects to enable compact 3D integration. The complete module was assembled by vertically stacking the antenna, alumina and control boards using low temperature indium solder balls. The fully assembled module was experimentally evaluated through radio frequency over-the-air measurements in an anechoic chamber. The results confirmed successful radio frequency beam formation after phase and gain calibration of the antenna elements which achieved an effective isotropic radiated power of 18.5 dBm. The demonstrated electronically steerable beamforming capability validates the proposed hybrid integration strategy and highlights its potential for next generation 5G radio frequency packaging and system-level integration.