Conformal coatings primary purpose is protecting the performance of highly sophisticated electronics such as printed circuit boards (PCBs), sustaining their functionality through often unfriendly operating conditions. Among the most important coating-requirement is safeguarding PCBs from the negative impact of moisture incursion. Sources are many. Liquidized obstacles to appropriate assembly function can result from unwanted contact with acid rain, aggressive solvents, atmosphere pollutants, chemicals, fog, high humidity, intermittent immersion, persistent rain, snow, salt water/mist and wet sprays of any kind.Read More
Parylene Coating Blog by Diamond-MT
Used as moisture and dielectric barriers, polymer parylene (p-xylylene/XY) coatings are conformal and pinhole free. Applied by a unique chemical vapor deposition (CVD) method, parylene penetrates beneath substrate facades, simultaneously attaching above surfaces at the molecular level. CVD generated films cover crevices, exposed internal regions, points and sharp edges uniformly, without gaps or breaches. Compared to liquid coating materials – acrylic, epoxy, silicone and urethane -- XY film layers are micron-thin, enhancing their utility for microelectricalmechanical systems (MEMS) and nano technology (NT).Read More
Parylene (XY) conformal coatings are known and recommended because of their many beneficial performance characteristics. They provide uniform, pinhole-free protective films with excellent barrier/dielectric/insulative properties, able to conform to virtually any substrate configuration. One property in particular – micron-thin coating layers – distinguishes XY from liquid coating materials such as acrylic (AR), epoxy (ER), silicone (SR) and urethane (UR), which need to be applied at least twice as thick in most cases and frequently more, limiting their range of uses. Parylene typically is applied at 0.1 to 50 microns (0.004 -2 mils), while the thicknesses of liquid coatings generally range from 25 to 250 microns (1-10 mils). Compared to liquid processes, gravity and surface tension generate negligible impact with parylene, eliminating film bridging, pinholes, puddling, run-off, sagging or thin-out during application. XY’s coefficient of friction coefficient can be as low as 0.25 to 0.30.Read More
Of the five most commonly used conformal coatings, four – acrylic (AR), epoxy (ER), silicone (SR) and urethane (UR) – are classified as wet materials, meaning they are applied to substrates by three basic types of liquid-based technology:Read More
Each conformal coating material exhibits a range of unique performance properties that determine its product uses. Relevant factors include the required coating-thickness necessary to assure reliable performance. Like other coating types, parylene (XY) layer thickness is largely a function of several factors: (1) substrate material, (2) the kind of assembly being covered, and (3) its operational purpose. Chemically inert parylene is effective at far-thinner application thickness than liquid-applied materials for coating printed circuit boards (PCBs) and related electro assemblies:Read More
WHAT ARE MEMS?
Microelectromechanical systems (MEMS) is the technology of very small devices; it merges at the nano-scale into nanoelectromechanical systems (NEMS) and nanotechnology. MEMS are made up of components between 1 to 100 micrometres in size (i.e. 0.001 to 0.1 mm), and MEMS devices generally range in size from 20 micrometres (20 millionths of a metre) to a millimetre (i.e. 0.02 to 1.0 mm). They usually consist of a central unit that processes data (the microprocessor) and several components that interact with the outside such as microsensors.
One of the different factors to take into account when trying to determine the proper parylene thickness is the amount of clearance needed. If it is a printed circuit board that is an enclosure, there usually will not be too many clearance issues. However, in some cases, even an extra mil of coating can cause extra mechanical abrasion to the parylene which can result in damaged parylene.