Laser direct writing of copper on polyimide surfaces from solution

Conductive copper patterns were deposited on polyimide (PI) substrates by using a focused, scanned continuous wave (cw) Ar+ laser beam at 488 nm wavelength. The deposition process was initiated by a photothermal reaction of a tartarate-complex solution of Cu2+ ions in an alkaline and reducing environment. Deposits were characterised by Field Emission Scanning Electron Microscope (FESEM), Energy Dispersive X-ray (EDX) Spectrometry, DEKTAK profilometer and resistance measurements. The dependence of the characteristics of laser direct written patterns on the scanning speed of the laser beam, number of scans and laser power was examined. Uniform copper lines covered with copper-oxide (line width from 30 to 60 μm and height from 2 to 20 μm) with high conductivity and adhesion were achieved under optimised conditions.