Progress in Replacing Decorative Electroplating Chrome Coatings on Plastics with Physical Vapor Deposition Coatings
Decorative electroplated chrome coatings on plastics have been produced for decades. For environmental reasons, there has been a shift away from hexavalent chrome (Cr6) to trivalent chrome (Cr3) with increased investments towards elemental chrome PVD coatings to maintain the true chrome appearance.
Decorative electroplated chrome coatings on plastics have been produced for decades. For environmental reasons, there has been a shift away from hexavalent chrome (Cr6) to trivalent chrome (Cr3) with increased investments towards elemental chrome PVD coatings to maintain the true chrome appearance. Stylists within industries such as automotive, still pine for the chrome look, but are looking for alternative solutions without the negative health impact of chrome electroplating and its processing effluents. For applications that must endure the sun, sand and highway, the acceptance criteria is increasing with exposures to a wider temperature range (from -70 to +150° C), higher levels of chemical attack from new highway deicing systems and from aggressive cleaning techniques. John A. Thornton  reported direct sputter deposition of chrome and other metals on ABS and base-coated ABS in 1975 and new developments continue to evolve to replace traditional decorative chrome plating.
ABS (acrylonitrile-butadiene-styrene) has been widely used as substrates for vacuum deposition and electroplating since the 1960s. The material is relatively inexpensive and can be easily injection molded, but for most applications where the part is directly exposed, or viewed through a clear lens, a base coating (of paint) to smooth the surface of blush and flow lines prior to vacuum deposition has been required. A more expensive plating grade ABS is used for components to be electroplated. PVD processing has greatly opened up the materials that can be directly coated including: ABS with polycarbonate (PC) blends, polyamide (PA), polyetherimide (PEI), polybutylene terephthalate (PBT), polystryrene (PS) and others.
Launched in 1988, Truck-Lite Co. Inc., in Jamestown, NY, and Vergason Technology, Inc. (VTI®), in Van Etten, NY, directly applied PVD coatings to PC without using a paint base coating. By placing the metalizing equipment next to the injection molding press, the parts were coated immediately after molding, while they were warm, dry, and free of fingerprints and dust. Class A mold finishes, eliminating the application of excessive mold release and timely cleaning the gas phase contamination from the mold surfaces were necessary to produce directly metalized mirror-like surfaces. After metalization, the substrates received the remaining processing steps in synchronous fashion until testing was completed and the parts were prepared for shipping. These techniques were the advent of LEAN manufacturing of PVD coatings which moved the metalization equipment upstream next to the injection molding operation. This is where the in-line process of Press Side® rapid cycle metalization was born and the scraps that fell off the large batch metalizing “King’s Table” became the food that launched a new genre of PVD processing for 3-D parts.