Opening of via-holes in flexible electronics by a UV-laser

Progress in laser technology over the years and its flexibility of use promise a wide range of methods for the fabrication of organic and large area electronics (OLAE). Several examples of laser-machining in the reel-to-reel process are discussed, such as dicing of devices, drilling of via holes and opening of contacts. In this paper we will focus on laser drilling of via holes applied directly on flexible substrates for a two layer interconnect metallization. The substrates consist of a 50 µm thick and 200 mm wide web of Polyimide (PI) or Polyethylenterephtalate (PET). The challenge is to stop the laser on a metallization of a few micrometer thickness. The second metallization layer is deposited afterwards by screen printing or sputtering. An ultra-violet solid state laser with five axes in a reel-to-reel environment is used.