An Evaporative Initiated Chemical Vapor Deposition Coater for Nanoglue Bonding

The authors present an evaporative initiated chemical vapor deposition (iCVD) coater and use it to establish a submicron bonding process for millimeter‐scale foils with potentially rough surface features. The coater uses a simple benchtop design suited to research labs, with pre‐heated metal pins instead of hot filaments, and direct evaporation of reactants within the chamber. Coatings of poly(glycidyl methacrylate) (pGMA) with thickness 100–800 nm are achieved at rates of 10–40 nm min−1 on substrates common in high energy laser compression experiments. Coating uniformities of 10–30 nm mm−1 are demonstrated in a ≈60 × 10 mm zone under the heated pins. As an aside, the authors further show the ability to coat intentionally non‐uniform layers in a monomer vapor diffusion gradient. Coatings are formed on both plastics and solids ranging from smooth, non‐burred silicon or lithium fluoride to rough and burred metals (aluminum and copper). These coated substrates are then chemically bonded under mild heat and pressure. Detailed surface, thickness, and cross‐sectional characterization is performed to confirm a submicron bond gap and to troubleshoot the common clearance issues from burrs, roughness, and surface curvature. Peeling and dropping bond strength tests confirm the bonds are robust, when coated and assembled under conditions to mitigate clearance issues. A simplified evaporative initiated chemical vapor deposition (iCVD) coater is developed for submicron bond gaps in materials with potentially imperfect surfaces. A robust bonding process is designed to overcome the most common irregular surface features (curvature, roughness, and burrs) followed from contact elasticity analysis. Bond gaps of 0.2–1.5 µm are achieved in combinations of common plastics, metals, and ceramic‐like foils.