A novel 2-in-1 heat management and recovery system for sustainable electronics

Overheating poses major challenges in miniaturized electronics, especially as their power consumption increases. For this reason, thermal management is a necessity for efficient electronics, and its optimization is a central task in the design especially for miniaturized compact electronics. On the other hand, recovering this waste energy could be beneficial for battery-free electronics such as wireless sensors and devices located in remote environments, where the charging or changing of batteries are challenging and delicate tasks. Furthermore, batteries are known for their storage capacity degradation over time and environmental pollution. This paper presents the design, development, demonstration, and validation of an innovative 2-in-1 heat management and recovery system for autonomous electronic devices. The design incorporates the use of thermal vias as in-package heat management and vertical thermocouples, enabling simultaneously management and recovery of the heat emitted from a Si-chip. The proposed design is fabricated in Low Temperature Co-fired Ceramic (LTCC) technology, allowing the creation of a monolithic package containing miniaturized multilayer microvias in the range of 90 µm using different materials to act as embedded thermal management and vertical thermocouples, simultaneously. The design consists of 20 lateral (Ag/Co) and 21 vertical (Ag/AgPd) micro-TEGs connected electrically in series in the system. The hybrid TEG is made by combining thick- and thin-film technologies, favoring the use of different materials and technologies with high power factors for further improvements in the field of thermal energy harvesting. The proposed design allows the management of 67 % of the IC temperature by reducing it from 246 °C to 80 °C using Ag and AgPd thermal vias. At the same time, the system recovers the lost thermal energy to generate 37.5 µW of electrical power at a temperature difference of 58 °C. The proposed approach allows simultaneously transitioning into green and sustainable battery-free electronics and enhances the devicés reliability by maintaining thermal stabilization in a miniaturized devices using a monolithic package.