Deep Proton Writing

Deep Proton Writing (DPW) is our in-house rapid prototyping technology for the fabrication of plastic micro-optical and micro-mechanical components. The concept of DPW is based on a local irradiation of a plastic (PMMA) substrate with a micrometer-sized collimated proton beam, according to a predefined pattern. The irradiation process changes the physical and chemical properties of the material in the irradiated zones. As a next step, a selective etching solvent is applied for the removal of the irradiated regions, allowing us to achieve high-precision micro-holes and high-quality optical sidewalls. Alternatively, an organic monomer vapour (MMA) can be used to expand the volume of the bombarded zones through an in-diffusion process. This enables the fabrication of spherical or cylindrical micro-lenses with different heights. If necessary, both processes can be applied to the same sample, yielding monolithically integrated components combining micro-mechanical alignment features with micro-lenses.

While DPW is clearly not a mass fabrication technique as such, one of its assets is that once the master component has been prototyped, a metal mould can be generated from the DPW master by applying electroplating. After removal of the plastic master, this metal mould can be used as a shim in a final microinjection moulding or hot embossing step. This way, the master component can be mass-produced at low cost in a wide variety of high-tech plastics.