Sub-micron digital printing for microLED microbumps and QD Color Conversion

Ultra-Precise Deposition (UPD) is an additive manufacturing technique for fabricating conductive and non-conductive features at a micrometer scale. The process does not require an electric field, the deposition can be made on any substrate (conductive and non-conductive, planar and 3D) and materials with viscosities up to 1 000 00 cP can be printed in full resolution range. The combination of unique features can be used for fabricating next-generation OLED, MicroLED, and QD-LED displays.
Due to precise pressure control and the system's design, UPD allows depositing material with femtoliter precision. Together with the possibility to deposit materials with viscosities up to 1 000 000 cP and high solid content the UPD technology can be used for depositing conductive microdots below 10 µm in diameter and a very high aspect ratio for flip-chip application (for example micro-LED assembly).
UPD technology can also be used for the deposition of color-conversion layers based on quantum dots. We demonstrated technology that allows direct deposition of Quantum Dots material, simplifying the whole process and reducing the overall manufacturing cost. Moreover, it increases resolution: microdots currently obtained on the market usually have about 50 μm, the minimum is 20 μm – while we demonstrated with UPD technology dots with a diameter of even less than 5 μm. Compared to other digital additive manufacturing techniques like inkjet and EHD, UPD technology allows the deposit of high uniformity and repeatability structures with the use of inks with a higher concentration of QDs. This, according to Beer’s law, directly affects light absorption by the QDs. The combination of unique capabilities of the UPD printing method provides the solution for efficient fabrication of QD color conversion for next-generation Micro-LED displays.