Direct welding between copper and glass substrates with femtosecond laser pulses

We demonstrate direct microwelding between glass and copper substrates by use of femtosecond (fs) pulses. The joint strength is as high as > 16MPa. A scanning electron microscopy cross-sectional image of the sample proves successful joining without voids or cracks. Furthermore, we show that, compared with ns-pulses, the use of fs-pulses can reduce the pulse energy required for welding by two orders of magnitude, leading to the suppressed effect of heat and to the precise control of the welded region. (C) 2008 The Japan Society of Applied Physics.