Parylene conformal coatings combine a number of properties that are attractive for use in a wide spectrum of applications. Their low dielectric properties, high mechanical strength, transparency, bio compatibility, chemical inertness against all of the common acids, bases and organic solvents, low water/gas permeability and thermal properties make them interesting for use in many industries. Also, pinhole-free Parylene conformal coatings with a thickness higher than 0.1 μm are possible and have been reported earlier . Therefore, understanding their deposition process and characteristics is important.Read More
Parylene Coating Blog by Diamond-MT
Parylene coating process involves 3 steps: sublimation, pyrolysis, and polymerization. At the first step, which takes place between 120°C - 175°C, the dimer parylene powder precursor is sublimized and pyrolysed forming the monomers (see Figure). Next, Pyrolysis takes place which is defined as the thermal decomposition of materials at elevated temperatures (above 500 °C) in an inert atmosphere and this reaction is irreversible. Finally, monomers get deposited onto the substrate and all the other surfaces available in the deposition chamber. Monomers form long chained polymers at this step.Read More
Multilayer conformal coatings are advantageous in resolving diffusion or stability issues. A vast amount of knowledge is available in the literature about the use of multilayered stacks of Parylene and stacks making use of different intermediate materials such as metals and so on. Mostly, use of Multiple layers of Parylene C was commonly reported for Medical Implants .Read More
The stability and insulation property of Parylene conformal coating is critical for the reliable operation of electronic devices throughout their lifetime (PCBs, MEMS, sensors, implants and so on.). The failure mechanism of the conformal coating layers is known to be due to pore formation, blistering, delamination and thinning or pinhole formation due to dielectric breakage of the coating over time , . Therefore, the surface where the interface between the conformal coating and the substrate will be formed is of high importance. The cleanliness of this surface has a great impact on the final results of the conformal coating process and the coatings durability. At Diamond MT we provide professional surface cleaning services ensuring the long lasting results for your components. Also, the parylene conformal coating thickness and parylene varieties required for different service are considerations to take into account. We offer our professional services to direct our customers. Some of the variables of different service conditions can be listed as:Read More
The answer is “No!”Read More
Parylene Process:Read More
Parylene is a transparent polymer that offers uniform and pinhole-free conformal coatings for printed circuit boards, medical devices, and microelectronics. Varieties of parylene are made available through a modification of the molecular structure of para-xylylene (Parylene N, C, D, and F-AF4, and F-VT4). Each modification results in a set of material properties that are applicable in different service conditions.Read More
Parylene conformal coatings are highly reliable and are highly sought after in applications such as military sensors to medical implants. Because, parylene coatings are colorless (transparent), thin (micro-scale) and uniformly deposited all over the target surface they are hardly visible to the naked eye. However, there are methods to detect or test the quality of the coatings that are designated by standards (MIL-STD, ASTM). These standards test coatings for the encapsulation properties of Parylene conformal coatings depending on where they will be used. Leakage current and accelerated lifetime tests under different conditions (salty water, temperature, etc.)Read More
Implications of Parylene Coating Thickness:Read More
Parylene is a transparent polymer offering uniform and pinhole-free conformal coatings. Different varieties of parylene (Parylene N, C, D, AF4, and F) formed by a modification in their molecular structure. Each modification results in a set of material properties that are applicable in different service conditions. The basic type of parylene derivatives is the Parylene N (poly-para-xylylene) monomer.Read More
A natural process, corrosion enacts chemical/electrochemical reactions that degrade and gradually destroy materials or components within a functional environment. The outcome can be dangerous and costly to repair.Read More
Parylene (XY) polymers provide robust, dielectric, micron-thin conformal coatings for a considerable range of electronic devices, most prominently printed circuit boards (PCBs). XY’s unique chemical vapor deposition (CVD) application method synthesizes in-process, depositing gaseous parylene deep into a substrate’s surface. CVD occurs on a molecule-by-molecule basis, conforming to all underlying contours, regardless of shape or position, to the nanometer, if necessary. Pre-synthesized liquid coatings lack many of parylene’s performance properties, having far less ability to successfully and conformally penetrate crevices in the substrateRead More
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
For conformal coatings, elongation is a measure of material ductility -- a specific coating's ability to undergo significant plastic deformation before rupture. A coating’s yield elongation is the maximum stress the material will sustain before fracture. Thus, computed parylene (XY) elongation measurements represent the total quantity of strain the conformal film can withstand before failure. While elongation is equal to a material’s operating failure strain, it has no exclusive units of measurements. Typically,Read More
Parylene (XY) conformal coatings are applied to substrate materials through a specialized chemical vapor deposition (CVD) process that completely eliminates the liquid phase of wet coatings. No initiators or catalysts are involved in CVD polymerization, which synthesizes truly conformal protective film in-process. This is in stark contrast to wet coating materials such as acrylic, epoxy, silicone and urethane, which are synthesized prior to application via, brush, dip or spray methods. Wet during application, liquid-coated substrates requiring further drying and curing.Read More
Parylene: Properties and ProcessesRead More
Parylene conformal coating (XY) provides insulative protection for complex electronic circuit assemblies expected to function through rigorous operating conditions -- potential chemical, electrical, moisture and vapor incursion during performance. Applied through chemical vapor deposition (CVD), parylene penetrates deep within substrate surfaces, generating a level of assembly security surpassing that offered by liquid coatings such as acrylic, epoxy, silicone and urethane. Yet, although XY is applied in a vacuum, it’s capacity to provide these extraordinary qualities does not exist in one. Parylene’s durable protective value depends on film adhesion, a quality subject to persistent, thorough inspection throughout the production process.Read More
Parylene Chemistry and Production RequirementsRead More
It is imperative to obtain proper adhesion of the coating to the substrate in order to truly reap the benefits of parylene conformal coating. Poor parylene adhesion, after all, can negate some of parylene's most-prized properties, including corrosion resistance, chemical resistance, moisture resistance, and dielectric strength. So, it's in an engineer's best interest to understand the importance of parylene adhesion and how to obtain it.
Parylene and acrylic resins are both conformal coatings. Most of the similarities stop there. Because their properties vary so much, they have their own unique uses and capabilities.
People often wonder if their project can be parylene coated. While there are huge list of items that can be coated with parylene, there are some limitations. One of these limitations is size.
Parylene offers the best protection against solvents of any conformal coating. It is also brings to the table excellent moisture and gas protection, very high dielectric strength, and is bio-compatible. Even with all of these benefits, there are still some disadvantages to using parylene versus other conformal coatings.
There are a couple different factors that go into decided parylene cost. One of these factors is the material cost. Parylene dimer can be anywhere from $100 to $10,000+ per pound depending on the type and quality. Other raw materials, such as the cleaning materials and adhesion promotion mediums, also factor into the materials costs for parylene.
Medical Conformal Coatings Used
While all conformal coating types can be used for different applications, for many medical devices, parylene is the way to go. Because parylene is biologically inert, FDA approval of parylene coated devices is well-documented. The coatings comply with USP Class VI plastics requirements and are MIL-I-46058C / IPC-CC-830B listed. Another benefit for medical devices such as stents and catheters is that parylene is entirely conformal, meaning that component configurations with sharp edges, points, flat surfaces, crevices or exposed internal surfaces are coated uniformly without voids or pinholes.
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