Surface Metallization and Electroforming on Vat-Printed Photopolymers: Activation, Seed Layers, Adhesion, Coverage and Qualification

Vat photopolymerisation provides geometrically complex polymer substrates and sacrificial mandrels that can subsequently receive metallic layers. Published routes include catalyst-containing stereolithography resins, ZnO-containing DLP resins activated by laser irradiation, grafted interfacial layers for electroless copper on ultra-smooth SLA substrates, selective palladium catalysis in vat-printed plastronic parts, thiol-rich photocurable networks that bind metal ions directly, and self-activating DLP resins containing inexpensive metal precursors. These studies demonstrate that printable geometry and metallizability are coupled: additives or catalytic precursors can alter optical cure behaviour, while roughening, grafting, laser activation and surface chemistry can change nucleation and adhesion. Electroforming on additively manufactured mandrels further shows that seed-layer uniformity and current distribution can control shell continuity and thickness. This Engineering Review therefore treats metallization as a multi-state qualification problem rather than a coating add-on. 3Dresyns conductive soluble resins and Ag/Cu conductive coating routes are included only as manufacturer implementation examples; their catalogue positioning is not treated as independent evidence of plating adhesion, shell integrity or electroforming performance.