Direct cold sintering of functional ceramics onto polymer circuit boards: a new low energy manufacturing route in electronics

Cold sintering is an emerging technology that permits densification of ceramics, ceramic/polymer and ceramic/metal composites at temperatures as low as 100 degrees C. A transient liquid is added to the ceramic powder which is then pressed and heated. Particle-sliding, dissolution and re-precipitation result in densification and the low temperatures enable co-sintering with polymers, metals and dissimilar ceramics. Metallised-polymer printed circuit boards (e.g. FR4 PCBs) are the basis of modern electronics. The metallisation is partially etched away and the required functional and passive components are soldered into position using 'pick and place' technology. Ceramic components such as varistors, thermistors and patch antennas are manufactured separately at high temperatures (>1100 degrees C) and are assembled on the PCB. Here, we propose a radically different approach in which functional ceramics for the fabrication of components are directly deposited/integrated onto the PCB through a cold sintering process at <150 degrees C, reducing the need for energy intensive manufacturing of separate ceramic components. The overall aim is to develop a disruptive technology that reduces both the cost and energy involved in the fabrication of printed circuits for modern consumer electronics.