In the last few years the introduction of affordable 3D printing techniques like fused deposition modeling (FDM) and stereolithography (SLA) is slowly changing the way mass production has always been intended. The possibility to obtain complex shapes in a short time directly at home, without using conventional manufacturing techniques, is a revolutionary concept that is finding a lot of different applications. However some limitations exist for 3D printing, the most important one being the manufacture of metallic objects. Metals offer many attractive properties like electrical and thermal conductivity or a good mechanical resistance, and for this reason the 3D printing of metallic objects is a strategic research field in additive manufacturing. Some techniques able to directly print using metals are available, but many limitations are present in this case. For this reason the most used method to obtain bulk metallic parts is the use of the printed polymeric version as a mold to cast the final object. In most applications however only a thin layer of metal is required and different methods can be used to coat a printed part, including PVD and all-wet metallization. The latter is in general preferred due to the low cost and the optimal coverage in the case of critical shapes of the printed part. Optimized methods are available for the metallization of FDM printed objects [1], while in the case of SLA manufactured samples only some aspects of the plating process are treated in the existing literature [2, 3].

The present work investigates an optimized method to metallize parts obtained with SLA 3D printing by mean of an all-wet process based on electroless plating. The behavior of different proprietary and custom made photocurable resins printed using a commercial laser stereolithographic printer is investigated. The coatings employed include nickel-phosphorus and copper, two metals typically deposited via electroless plating on polymers. The metallization is characterized from the fundamental point of view on planar samples, while in a second time some examples of complex shapes metallization are provided. In particular the metallization of micrometric parts is studied. Finally the possibility to deposit other layers of different metals via electrodeposition on the first coating obtained by electroless plating is analyzed.

[1] R. Bernasconi et al.; ECS Trans., 66 (19), 23 (2015)

[2] A. Macor et al.; Rev. Sci. Instrum., 83, 046103 (2012)

[3] B. Luan et al.; Appl. Surf. Sci., 156, 26 (2000)