Ultra-Small Via-Technology of Thinfilm Polymers Using Advanced Scanning Laser Ablation

In this paper a new process technology will be discussed which uses a laser scanning ablation process. Laser ablation of polymers is in principle not a new technology. Low speed and high cost was the major barrier for further developments twenty years ago. But the combination of a scanning technology together with a quartz mask has opened this technology to overcome the limitation of the current photo-polymer process. The new technology is described in details and the results of structuring BCB down to less than 4 μm via diameter in a 4 μm thick film has been demonstrated. The via-side wall can be controlled by the fluence of the laser pulse.