Direct Processing of PVD Hard Coatings via Focused Ion Beam Milling for Microinjection Molding

Abstract

Hard coatings can be applied onto microstructured molds to influence wear, form filling and demolding behaviors in microinjection molding. As an alternative to this conventional manufacturing procedure, “direct processing” of physical-vapor-deposited (PVD) hard coatings was investigated in this study, by fabricating submicron features directly into the coatings for a subsequent replication via molding. Different diamondlike carbon (DLC) and chromium nitride (CrN) PVD coatings were investigated regarding their suitability for focused ion beam (FIB) milling and microinjection molding using microscope imaging and areal roughness measurements. Each coating type was deposited onto high-gloss polished mold inserts. A specific test pattern containing different submicron features was then FIB-milled into the coatings using varied FIB parameters. The milling results were found to be influenced by the coating morphology and grain microstructure. Using injection–compression molding, the submicron structures were molded onto polycarbonate (PC) and cyclic olefin polymer (COP). The molding results revealed contrasting molding performances for the studied coatings and polymers. For CrN and PC, a sufficient replication fidelity based on AFM measurements was achieved. In contrast, only an insufficient molding result could be obtained for the DLC. No abrasive wear or coating delamination could be found after molding.

Advanced Injection Molding Methods: Review

“…Research on the microforming process is developing at a very intensive pace, leading to the gradual elimination of the limitations of this process. In the process of injection microforming, thermoplastic materials are mostly used, and thermosetting materials are used to a lesser extent [157,158]. However, it should be mentioned that when thermoplastics are used, mostly those with low viscosity are used.…”

Enhancing structural replication of microfluidic chips: Parameter optimization and mold insert modification

“…Orth et al 18 found that the use of coated steel molds resulted in higher molding efficiency and 20% ~ 30% improvement in replication quality. Ruehl et al 19 successfully replicated submicron structures with an aspect ratio of 0.4:1 (height 190 nm) by using injection compression molding and found that the fidelity of replicating submicron structures and the demolding behavior depended on the combination of coatings and polymers. Zhang et al 20 demonstrated that the nickel‐based composite molds fabricated by electroforming could effectively reduce the friction coefficient and improved the polymer microstructure quality during hot embossing.…”

Patterning of COC Polymers by Middle‐Energy Ion Beams for Selective Cell Adhesion in Microfluidic Devices

“…Furthermore, the process can be integrated into existing microfabrication workflows like hot embossing, enabling scalability for mass production. [69,70] This study focuses on the surface modifications of thermoplastic COC polymers, specifically the TOPAS brand, for achieving selective cell adhesion using middle-energy ion beam patterning. We explored the use of energetic ions of oxygen, nitrogen, and carbon with fluences of 3.75 × 10 12 , 3.75 × 10 13 , and 3.75 × 10 14 cm −2 at an energy of 600 keV.…”

“…Furthermore, the process can be integrated into existing microfabrication workflows like hot embossing, enabling scalability for mass production. [ 69,70 ]…”