Publications

Laser ablation of thin films on LTCC

Girardi, M.A.; Peterson, K.A.; Vianco, Paul T.; Grondin, R.; Wieliczka, D.

Direct Digital Manufacturing techniques such as laser ablation are proposed for the fabrication of lower cost, miniaturized, and lightweight integrated assemblies with high performance requirements. This paper investigates the laser ablation of a Ti/Cu/Pt/Au thin film metal stack on fired low temperature cofired ceramic (LTCC) surfaces using a 355 nm Nd.YAG diode pumped laser ablation system. It further investigates laser ablation applications using unfil ed, or 'green', LTCC materials: (1) through one layer of a laminated stack of unfiled LTCC tape to a buried thick film conductor ground plane, and (2) in unfiled Au thick films. The UV laser power profile and part fixturing were optimized to address defects such as LTCC microcracking, thin film adhesion failures, and redeposition of Cu and Pt. An alternate design approach to minimize ablation time was tested for efficiency in manufacture. Multichip Modules (MCM) were tested for solder ability', solder leach resistance, and wire bondabilify. Scanning election microscopy (SEM) as well as cross sections and microanalytical techniques were used in this study.