Product Code: PIC2008_M603

Laser Direct-Write using Air-Drying Conductive Paste (Invited Paper)
Authors:
Daniel Perkins, Texas Christian University; Ft. Worth TX USA
David Willis, Southern Methodist University; Dallas TX USA
Jason Stegall, Southern Methodist University; Dallas TX USA
Presented at PICALO 2008

Laser direct-write was performed using commercially available silver paste to deposit patterns in an additive manner. The paste was a 60 % colloidal paste of 0.4 1.0 micron silver particles in a binder that dries under ambient conditions. Transfer was performed using a focused laser spot size of 110 micron and a spacer was placed between the paste and acceptor substrates to prevent contact prior to transfer. Process parameters including laser fluence, paste thickness, and spacer thickness were varied to find conditions for transferring features with minimal spreading and spattering. Feature sizes smaller than the laser spot were obtained under some conditions, since the paste was transferred in a drop-like manner. Continuous deposits of silver particles were formed by scanning samples under the laser focal spot. The thickness of the deposited features was controlled by changing the center-to-center spacing of overlapping laser spots. Measurements were taken of the cross-sectional profile and the electrical characteristics of the deposited features.