Optimization of UV-LED curable printing material for applications in direct writing systems: Inkjet, reverse offset, and micro dispensing GPD
The quality of a product fabricated by direct writing methods will depend greatly on the properties of the printing material and its compatibility with the printing process. Although multiple advances in developing printing inks and pastes with novel properties are being made, the potential those can bring to electronics is hindered by their stability and performance during the printing process. In this study a UV-LED curable acrylic material was used to test the optimization of inks and pastes for three of the most common direct writing systems: Piezo-type Inkjet, Reverse Offset Roll to Plate, and Micro Deposition. The viscosity of the photosensitive acrylic matrix was controlled by either the addition of diluents or electronically functional reinforcement material. The contact angle of the optimized solutions on 16 different Polyester, Polyimide, and Paper films was observed. Solutions with larger contact angles showed better line definition for the Inkjet and the Micro Dispense systems. In addition to the contact angle differential, the rheological properties showed to be a determinant factor for the feasibility of a solution to undergo the reverse offset printing process. The UV curable acrylic demonstrated electrical conductivity when 2% (wt.) MWCNT were ultrasonically mixed in the matrix and then cured with a 385nm wavelength for 3 seconds. Only the micro deposition system was capable of printing the acrylic-MWCNT paste and the relationship between the contact angle, pattern accuracy, substrate selection, and electrical conductivity, was determined.
Varela, Ada Judith Ortega, "Optimization of UV-LED curable printing material for applications in direct writing systems: Inkjet, reverse offset, and micro dispensing GPD" (2014). ETD Collection for University of Texas, El Paso. AAI1557780.