Additive Manufacturing for Flexible Electronics

Additive manufacturing, also referred to as 3D printing, has seen innovation in several critical areas in the field of electronics packaging and assembly from wafer level to printed circuit boards for low volume manufacturing and prototyping. Ceramic interposers are being manufactured using vat photopolymerization technologies to create substrates with channels for interconnects, that are backfilled through the process of metal infiltrations [1] The unique geometries enabled by the layer-to-layer technologies allow for routing options not possible with traditional fabrication techniques or fabrication quantities that are not economically viable. Semiconductor die pads to package substrate interconnects through 3D printed traces have been explored to replace traditional wire bonding connections. This enables smaller form factors as the wire height requirements are replaced with flat aerosol jet printed conductive traces created using nanoparticle inks [3]. The formulations of the conductive ink still pose challenges with material compatibility between interfaces [4], electrical resistance, and limited thermal operational ranges as each company creates material best suited to their printing system [2]. Printed interconnects open the doors for faster turnaround time, performance improvement through impedance matching for packaged devices [3], shorter interconnect lengths, and chip scaling through tool path alterations [4]. Additively manufactured printed circuit board assemblies which utilized printed traces and interconnects have also integrated printed passives such as resistors and capacitors into the boards [5]. These targets eliminating the need to pick and place passives in the assembly process as potentially any passive desired could be printed onto the boards. The three-dimensions fabrication methods also allow for the resistance values to be adjusted within a limited space. Virtually every DoW system with electronics requires PCB manufacturing. Commercially available Substrate Manufacturing techniques and Advanced Packaging techniques are extremely expensive and require long lead times and are therefore not conducive to High Mix - Low Volume manufacturing efforts. It is desired to improve and validate existing additive manufacturing methods for use on government and commercial systems. Existing additive substrate fabrication and additive advanced packaging methods have been proven to be flexible, adaptable, and cost effective, there remains an undefined reliability risk. DoW is looking to enable these technologies. Specifically, by obtaining reliability data using MIL-STD quality and reliability metrics, these additive manufacturing technologies could become a viable alternative to traditional substrate manufacturing and advanced packaging. As a Phase I study, DoW is seeking the feasibility of developing a prototype via this effort directly comparable to existing Radio Frequency multichip modules (MCMs) currently used by the DoW. Additionally, the feasibility study may offer additional miniaturization or other forms of improvements that are of extreme interest to DoW. If such technology can produce prototypes with reliability comparable to standard manufacturing or reliable enough to fulfill target DoW missions, the additive manufacturing technologies could be used extensively on relevant microelectronic designs to reduce cost and manufacturing timelines for DoW Programs.