Engineered Porous Metal Structures via Electroplating in Two-Photon Polymerized Molds

We report the realization of metallic 3D microstructures, electroplated in two-photon polymerized molds. These molds are typically 150 × 150 × 30 µm3 in size and the smallest feature size is about 1 µm. After the electroplating process, the mold is removed by means of CF4/O2 etching (1 h). The vertical electroplating growth is about two times higher than the horizontal growth, which creates voids. A new design to prevent voids was tested where the pores were arranged at a 35° angle to the chip surface. The remaining structures consisted of a copper base with a palladium finish, or of pure palladium. They were analyzed through SEM and were shown to be a good reproduction of the mold design, resulting in metallic porous structures with a specific surface area of about 6 mm2/mm2.