Metallizing 3D-Printed Substrates via Manganese Etching

The patent changes the chemical composition parameters of the etching solution by replacing chromic acid with manganese-based compounds (such as manganese dioxide, manganese sulfate, or potassium permanganate) combined with organic acids (like citric acid, oxalic acid, or malonic acid). This substitution maintains the etching capability while eliminating the environmental harm associated with hexavalent chromium, thus resolving the contradiction between etching strength and environmental sustainability.

The patent employs a composite etching system combining manganese-based oxidizing agents with specific organic acids and surfactants. The manganese compounds provide strong etching power for maintaining productivity, while the organic acids and surfactants ensure uniform penetration and reaction across the 3D-printed substrate surface, preventing localized over-etching or under-etching. This composite approach resolves the contradiction between etching speed and surface uniformity.

The patent applies a preliminary treatment step using the manganese-based etching composition before metal deposition. This preliminary etching creates an optimal surface morphology with controlled roughness that enhances metal layer adhesion through mechanical interlocking and chemical bonding, while the controlled nature of the manganese-based process prevents excessive etching that would create surface defects. The treatment is followed by a rinsing and drying step to prepare the surface for metallization, thus resolving the contradiction between adhesion strength and surface quality.