Authors:
Nicholas S. Dellas
Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802

Kenneth Meinert
Applied Research Laboratory, The Pennsylvania State University, University Park, Pennsylvania 16802

Suzanne E. Mohney
Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802

Copper (Cu) has been patterned using a laser direct-write metallization technique for fabrication of printed wiring boards. The approach consists of writing a silver (Ag) seed layer with a subsequent step of electroless Cu plating to increase thickness and electrical conductivity. Ag seed layers were patterned with a frequency tripled Nd:YVO₄ (λ=355 nm) laser with a spot size of approximately 50 μm. Final Cu linewidths after electroless plating were found to be 150 μm with a thickness of 2 μm and electrical resistivity of 5 μΩ cm. An optimal laser power of 0.81 W was found by a factorial-type design experiment. A modern prototype circuit was also patterned with this technique, demonstrating its compatibility with current resolution requirements.