Sintering strategies for inkjet printed metallic traces in 3D printed electronics

Abstract

Emerging from 2D printed electronics, 3D printed electronics promise a break-through in additive manufacturing and prototyping of electronics. However, transferring the know-how from 2D flexible electronics to 3D parts with complex structures (e.g. internal vias and external interconnects) might not be a straightforward approach. As an example, the variation of light intensity with respect to the distance and angle of incidence casts doubt on the efficiency of the intense pulsed laser (IPL) as a robust sintering method for metallic traces in 3D printed bulk structures, whereas IPL is currently by far the most prevailing sintering technique for 2D printed flexible electronics. Sintering of metallic traces in 3D printed parts can be executed either as a sequential layer-by-layer printing and processing step (LP) or as a bulk post-processing step (BP). In the current study, a survey on the most common sintering strategies for inkjet printed silver nanoparticles was conducted, while the compatibility to 3D printed structures was brought into the focal point. To discover the capabilities and limitations of six sintering methods (i. e. IPL, ohmic curing, thermal heating, laser, atmospheric plasma and microwave sintering) for 3D printed electronics, a comparative study utilizing the same materials and diagnostic methods was pursued. The results revealed that for 3D functional parts, some of the sintering techniques can be considered as complementary methods for each other, whereas a few showed readily the potential to be adapted in 3D printed electronics production.

The Realization of Redistribution Layers for FOWLP by Inkjet Printing

“…The most efficient sintering methodology for the printed Ag RDLs (e.g., pulsed light sintering, thermal sintering, plasma sintering etc.) was subsequently determined by means of the four-point probe measurements [8]. In fact, since different materials with divergent surficial and physical properties are found in SiP, which are exposed to the light or plasma source concurrently, the uniform treatment of the inkjet printed Ag nanoparticles was not effective.…”

3D Printing of Multilayered and Multimaterial Electronics: A Review

“…For sintering metallic film, it is important to note that a presintering step is required for electrical and induction sintering techniques to make the printed film slightly conductive (≈0.15% of bulk material's electrical conductivity) for the subsequent treatments. [ 178,179 ]…”

Nanomaterials-patterned flexible electrodes for wearable health monitoring: a review

“…Moreover, the surface deposition of metallic nanomaterials requires sintering process. The sintering process is the removal of liquid phase carrier solution to produce a continuous thin film on the substrate [ 113 ]. Moreover, nanomaterials often cause problem during inkjet printing by the formation of the coffee ring effect, which is the aggregation of nanomaterials along the edges of a circular droplet [ 114 ].…”