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48 SMT007 MAGAZINE I OCTOBER 2021 composition products of a common solvent, p- xylene, at a temperature between 700 and 900°C. Union Carbide scientist William Gorham lat- er developed a deposition process to apply the film. He deposited parylene films by the thermal decomposition of di-p-xylylene at 550°C and in vacuum below 1 Torr, a process that did not re- quire a solvent and resulted in chemically re- sistant films free from pinholes. In 1965, Union Carbide commercialized the material and the chemical vapor deposition (CVD) process that is unique among conformal coatings. While the barrier properties of parylene are unmatched, it adds minimal mass to coat- ed surfaces and contributes no cure or ther- mal expansion forces to threaten delicate com- ponents. Parylene has exceptional tensile and yield strength, is dielectric, and can cover the entire board to protect component leads, sol- der joints, exposed traces, and other metalized areas. It provides protection from corrosion, and shields the whole PCB from spray, mois- ture, fungus, dust, and other contaminations from harsh environments. Parylene even helps prevent damage to circuitry and sensitive com- ponents from thermal and mechanical stress as well as rough handling, or in the case of AMRs, bumps, and jarring during deployment. Parylene conformal coatings consist of a protective polymer layer 12–25 µm thick (<20 µm typical) that conforms to a PCB's shape and components. ey provide resistance to solvents and chemicals, are heat resistant, and help prevent light component leakage and cor- rosion. ey are the best protective strategy for PCBs that will be exposed to unfavorable environments. e impediments to parylene's wide adop- tion have been cost and scalability. e raw materials have been historically high-priced, and scalability with manufacturing integration is complex. HZO has broadened the scale of usage for this robust, organic material by mak- ing it available to companies and manufactur- ers that could not previously consider it an op- tion. At the foundation of its offerings are engi- neers and scientists with deep domain and in- dustry expertise in conformal coatings, and its in-house proprietary equipment. Although there are different ways to apply coatings—brushing, spraying, dispensing, and dipping—HZO uses the chemical vapor depo- sition (CVD) process to create truly uniform conformal coatings. CVD is a coating method that flows reactive gases into a vacuum cham- ber containing the target substrates, where the chemistries combine or react to form a confor- mal coating. In HZO's case, these reactive con- stituents are formed thermally, but the reac- tions on the product happen at room temper- ature. HZO's optimized chamber size and shape en- sures uniform parylene deposition and a pro- prietary state-of-the-art controller that can re- motely monitor and control real-time critical factors, like temperature, pressure, and other essential operating parameters. e precision and control of its systems ex- tend the use of parylene to more consum- er electronics, medical devices, IoT, industri- al, and automotive applications by meeting tighter tolerance, thinner film depositions, and higher quality standards. HZO's equipment employs a proven application method for both small batch and high-throughput environ- ments. Semiconductors, printed circuit board While the barrier properties of parylene are unmatched, it adds minimal mass to coated surfaces and contributes no cure or thermal expansion forces to threaten delicate components.