​Researchers from Leti, a CEA Tech institute, presented a silicon component encapsulated in a polymer package using 3D printing—a world first. A major technical hurdle to the advance was the adherence of the polymer to the silicon. To find a solution, the researchers tested several finishes (organic, metal, and inorganic) to help the polymer adhere to the substrate. 

The electronic circuits were fabricated on 200 mm wafers; test components were then added and connected using wire bonding. Finally, the system was encapsulated by 3D printing layers of polymer structured using a stereolithography (or SLA) printer at Liten’s Poudrinnov’2 platform. The plastic “shell” protects the fragile stack. For more complex designs (with cavities, channels, or domes, for example) it can also enable additional functions.

A demonstrator system was presented at ECTC in June 2018, where it garnered interest from several industrial companies. Leti is currently working with a 3D-printer manufacturer to bring the thickness of the SLA-printed layers down to less than 50 microns. Ultimately, metal 3D printing techniques could be used to enable new capabilities, like creating interconnections and antennas. The two types of printing—polymer and metal—could even be combined on the same printer.