POPEYE - Plating On Plastics Equation-based sYstems Engineering: Unit operations and properties prediction models for emerging plating on plastics technologies

Plating on Plastics (PoP) is a continuously growing manufacturing technology for the production of several everyday (e.g. home appliances, automotive compartments) and advanced (e.g. aerospace) applications. The traditional process uses toxic Cr⁶⁺ and Pd critical raw material raising environmental, health, and supply concerns. This work presents a process systems engineering framework for the modeling, design and optimization of a novel SSbD PoP technology (EU-Funded FreeMe project) replacing Cr⁶⁺ and Pd with piranha solutions (H₂O₂–H₂SO₄), nickel-salts and NaBH4 for the pretreatment of plastic surfaces before metallization. State of the art and data-driven models were developed for the four proposed novel processing stages (i) etching with piranha, (ii) surface activation with nickel-salts, (iii) surface reduction with NaBH4, and (iv) metal plating.

A contact angle property prediction model was developed as a function of the etching conditions describing the piranha etching mechanism. The clever use of data and models further enables the correlation of contact angle with the hydroxyls surface concentration quantifying etching performance. Next, an activation efficiency model and a surface reduction kinetic model were developed as functions of process conditions. Last but not least, a regression method enhanced with data re-mapping was constructed as an extrapolable model for the prediction of the coating adhesion specification on the plastic substrate with respect to surface characteristics.

The models were constructed as an optimization Decision Support Tool considering economic, environmental, safety and SSbD objectives to assist PoP practitioners optimally tune their pilot/industrial lines for SSbD plating on plastics using the new technology. A BETA version of the DST was developed for stakeholders’ experimentation enabling the user to define their production characteristics and requirements (adhesion, thickness). All process operating variables for PoP of 6 items of 150 cm2 (each) were optimized reaching adhesion (2.5 MPa) and thickness (25 μm) specifications at optimal SSbD criteria.