Nanocoating vs Parylene

Although its basic component is remarkably small–-25,400,000 nanometers per inch–nanotechnology encompasses a growing, interdisciplinary field with an unlimited future. Nanowires and nanotubes are used in transistors for printed circuit boards (PCBs) and associated electronic assemblies. Bio-nano batteries, capacitors, LCDs and microprocessors represent just a few nanotechnology applications.

Uses of Nanocoatings

Conformal coatings protect electronic components from moisture and contaminants to assure their functionality under stressful operating conditions. Like other electronic assemblies, nano-components require protection during operation and storage. Because of their microscopic size, nanocoatings are, at first glance, the optimal protective covering choice for nano-devices in comparison to liquid conformal coatings. The film thicknesses required for these liquid coatings to provide effective protection are too great for nano-devices, essentially defeating the advantages of their minute proportions by interfering with their function.

In Comparison to Parylene

Parylene has been shown effective for most MEMS/nano applications, even though its conformal films are considerably thicker than those generated by nanotechnology. Nanocoatings dry to a thickness of 100 – 5,000 nanometers (0 – 0.0002 inches). In contrast, Parylene coatings typically measure 0.000394 – 0.00197 inches. Statistically, the Parylene measurements are significantly larger. Parylene’s smallest coating thickness (0.000394 in.) is nearly twice as substantial as the largest nanocoating (0.000200 in.); however, the thicknesses of both coatings are minuscule. Parylene remains sufficiently small for effective MEMS/nano conformal coating.

To achieve maximum effectiveness, coating thicknesses for both nanocoatings and Parylene conformal coatings need to demonstrate complete film homogeneity/substrate adhesion on specified PCB/assembly areas. It must exhibit the absence of surface blisters, fractures or other conditions that might affect the coating’s sealing competence or assembly operation as well as freedom from bubbles, cracks, foreign materials, peeling, voids or wrinkles that would expose the PCBs components or conductors, or violate specified electrical clearances.

Depending on the particular application, Parylene easily matches nanocoating’s uses for a wide range of aerospace, automotive, consumer electronic, defense and medical applications. And while certain nanocoatings can generate no-mask solutions that deliver the benefits of conformal protection against moisture, they often lack the impact-resistance and corrosion defense of Parylene. Nanocoating’s capacity for coating rework is largely negated by its comparative lack of resilience and strength under the same range of operating circumstances common to Parylene coatings.

Methods of Application

Nanocoatings can be applied through wet dip or atomized-spray methodologies, while post-application curing is generally limited to air drying. Similar to Parylene, nanocoatings can also be readily applied through chemical vapor deposition (CVD) and single-step plasma deposition techniques. Nano-plasma deposition utilizes a single-step process to apply a thin, uniform film that does not rely on solvents and requires no curing.