Recent Breakthroughs in Tight Pitch Laser Microdrilling for Mems Guide Plates

Laser drilling of guide plates for Advanced Vertical Probecards has become a key enabling technology over the past several years. Amongst the key drivers is the switch in demand from circular shaped holes, achievable with both mechanical and laser drilling methods, to rectangular holes for MEMs style probes. These rectangular holes can only readily be produced with the use of laser technology. As semiconductor technology and wafer test advances, an additional driver is high density hole drilling, i.e. the ability to place smaller and smaller holes on tighter and tighter pitches, whilst keeping the material between adjacent holes intact. Typically, the 3D shaped profile of laser drilled holes cannot easily be controlled, with so called “entry rounding” and “taper angle” characteristics restricting tighter hole positioning. The challenge is therefore to develop new processes which essentially eliminate both entry rounding and taper to values of virtually zero. After a recent breakthrough this has now been achieved.