SMT007 Magazine

SMT007-Aug2019

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36 SMT007 MAGAZINE I AUGUST 2019 tions 14.2.7 and 14.2.8 for IPX7 and IPX8 des- ignations, which demonstrates protection from harmful effects due to the ingress of water. The uncoated (control) electronics functionally failed during the test, but all ParyFree-coated electronics passed both test conditions, func- tioning normally both during and after testing. These tests demonstrate that ParyFree confor- mal coating, like other Specialty Coating Sys- tems (SCS) Parylene variants, is suitable to protect electronics and other devices against water splash and water immersion for more than 30 minutes at a depth of 1 m (IPX7) and 1.5 m (IPX8). Protection From Electrical Arcing and Electrostatic Discharge Electronics have long been susceptible to electrical arcing and electrostatic discharge (ESD). However, modern devices are actu- ally more susceptible to these electrical risks because individual components are smaller. Additionally, contact points are also closer together, and thinner wiring simply cannot withstand the same sudden jolt as the thicker wiring of older equipment. If not protected, such electrical mishaps can cause premature device failure. Parylenes have very high dielectric strength— up to double that of other coatings of the same thickness. As such, they provide excel- lent insulating protection to prevent damage from arcing and ESD without adding signifi- cant mass. For example, a 25-micron Parylene coating will have a dielectric capacity of 7,000 volts. No other coating can be applied as thin as Parylene and still provide the same level of protection. Stability to Endure Thermal Cycle Extremes, Pressure, and Vibrations Electronics used in automobiles, aircraft, oil drilling, and space exploration are exposed to harsh environments and expected to oper- ate reliably in them. Circuit card assemblies in the wing of a jet or in a rocket carrying a satellite into space, for example, will travel quickly from ambient, sea-level temperatures to a stratospheric altitude at subzero temper- atures. In addition to the temperature change, the tiny, delicate mission-critical electronic cir- cuits have to endure rapid pressure changes and intense vibration as part of the ride. Some of the protective methods that have been successful in earth-bound applications can fail in the atmosphere of space. Air that may be trapped under an epoxy or acrylic sealant due to the nature of coating application can release, leav- ing critical components unprotected in the midst of a flight or operation. Parylene HT was specifically designed to protect components that must survive exposure to harsh, high- temperature environments. The coat- ing is thermally stable in air at 350°C (long-term) and remains stable with short-term excursions to 450°C, offer- ing excellent protection to many aero- space, defense, and transportation applications. Parylene HT is also UV- stable. Parylene coatings, though ultra-thin and lightweight, have been known to strengthen fine components and wire bonds, helping to secure delicate elec- tronics. Additionally, due to the film's Halogen-free ParyFree protects a wide range of consumer electronics devices.

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