Surface functionalization of flexographic printing forms using a femtosecond laser for adjustable material transfer in MID produ
SPIE Photonics West: LASE
To bring the well-known advantages of optical data communication onto flexible substrates, an efficient and low cost approach to manufacture Opto-Mechatronic Interconnect Devices (Opto-MID) is under development. It is realized by a two or three step process. First, the carrier substrates are preconditioned by means of flexographic printing. Subsequently the polymeric optical waveguide material is applied by aerosol jetting. If a three-dimensional shape is required, thermoforming is performed as third process step. The printing quality is crucial since the quality of the waveguides strongly depends on the shape of the preconditioned lines – especially the edge waviness. Furthermore, forming the substrate three-dimensionally, a spatially resolved material distribution is required for optimal results. A way to face these challenges is to functionalize printing forms using femtosecond laser pulses. By laser microstructuring the material transferring areas of the printing form, the surface energy, and therefore the material transferring behavior, is changed. Microstructures of different shapes and sizes affect the wettability and are thus investigated. Because the printing form consists of synthetic material, the chemical stability over time is also an important factor. Furthermore, printing results of the functionalized printing forms are classified by means of suitable parameters, such as material transfer, material distribution, edge waviness, and repeatability. Finally, since during printing the material transferring areas are constantly exposed to mechanical pressure, investigations on the wear of the functionalized surfaces are presented.