(Electrodeposition Division Early Career Investigator Award) Wet Metallization of Additive Manufactured Parts: State of the Art and Future Perspectives
Authors: Bernasconi Roberto 
Published: December 2024

In the context of the fourth industrial revolution, Additive Manufacturing (AM) is probably the most relevant key enabling technology. This family of techniques overcomes the well-known limitations of conventional subtractive fabrication by introducing advanced manufacturing strategies based on a simple concept: the layer-by-layer building of a real object starting from a digital 3D model [1]. By implementing this approach, production can be made more scalable and customized, while material and energy use can be highly improved. With AM, it is possible to optimize parts design and even to get shapes impossible to obtain using conventional subtractive techniques. Depending on the technique selected, AM is also capable of working at the microscale.
In analogy with conventional manufacturing, some applications may require the application of thin functional layers on the parts obtained via AM. Such layers can be used to impart specific properties, like conductivity (in the case of insulators), magnetic properties and wear or corrosion protection. Since the most diffused AM technologies operate with polymers, the most industrially relevant scenario is the deposition of functional layers on polymeric manufactured parts. This consideration poses the stimulating challenge of finding cost effective and highly productive strategies to deposit such layers. The most promising way is realistically wet metallization, which allows the deposition of a wide selection of heterogeneous materials via techniques like electrolytic or electroless deposition.
The wet metallization of AM parts offers challenges and problematics, but also opportunities. In addition to the uniform application of coatings to parts manufactured with the most common techniques (fused deposition modelling [2], stereolithography [3], digital light projection ...), wet metallization also offers the attractive possibility of selectively depositing the material of choice. This approach, based on selective electroless activation or on the use of self-activating materials [4] coupled with multimaterial 3D printing, makes possible transferring conductive metallic patterns onto non-conductive substrates.
Given the scientific and industrial relevance of the topic, the present work aims at reviewing the most interesting approaches currently available for the wet metallization of polymeric AM parts. The discussion focuses on the metallization approaches available for the different AM techniques, highlights the most promising strategies for selective plating and reviews some of the most interesting applications. Finally, the work also discusses the outlooks and the realistic industrial applicability of wet metallized 3D printed parts.
[1] I. Gibson et al., “Additive manufacturing technologies”, Springer (2021)
[2] R. Bernasconi et al., J. Electrochem. Soc., 163(9), D526 (2016)
[3] R. Bernasconi et al., J. Electrochem. Soc., 164(5), B3059 (2017)
[4] C. Credi et al., J. Mat. Res. Tech., 22, 1855-1867 (2023)