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
Parylene Coating Blog by Diamond-MT
At Diamond MT we often get the question: “Can my xxx be parylene coated?” The number of substrate surfaces that can be coated with parylene is plenty. In the table below a number of industrial applications that using Parylene conformal coatings are listed. The examples can be extended.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
Poly(para-xylylene) derivatives (parylenes) are used as conformal coatings in a wide range of applications in the automotive, medical, electronics, military and semiconductor industries. They are inert, transparent and have excellent barrier properties as dielectric thin films. Because their deposition takes placeunder vacuum sub-micron range crevices can be coated leading to excellent barrier properties (void free) and they have extraordinary purity that is of great importance in electronic applications. Not all parylene derivatives show same dielectric properties (Table 1). It is also important to note that dielectric properties of parylenes depend on their thickness thus their %crystallinity which is explained below.Read More
The answer is “No!”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
Today, security systems rely on different types of advanced, intelligent and connected sensor technologies. Application areas are diverse: radar systems, vision, night vision (IR-cameras), acceleration- orientation-location detection (accelerometers, gyroscopes, GPS), chemicals (neural toxins, other toxic gasses, liquids, materials), wearable sensors (body temperature, relative humidity, location detection), barometric (under water), air flow (aerospace, missiles) and they are brought together for multifunctionality on PCB’s which carry many sensor at a time. Sensors used in military applications pose stringent requirements such as robustness under severe environmental conditions and require longevity of sensing functions. Some of the environmental conditions that are harsh on sensors can be listed as:Read More
Used for aerospace. automotive, commercial, defense, industrial and medical applications, conformal coatings are applied in film layers generally 30-130 microns (micrometers/μm) thick, or 0.0012-0.0051 inches (“). Conformal films’ exceptional thinness is their greatest asset. Coatings safeguard printed circuit boards (PCBs) and similar electronics from performance malfunction generated by unwanted contact with:Read More
Conformal coatings are non-conductive dielectric film-coverings applied over printed circuit boards (PCBs) to protect them from damage caused by chemical incursion, corrosion, current-leakage, dirt/dust, extreme temperatures, fungus, moisture, rain, salt-spray, wind and persistent, intensive vibrations both within and external to the device. These failure mechanisms can soon lead to PCB malfunction and eventual breakdown. Rugged coatings’ exceptional performance durability and versatility protect delicate, finely-tuned components.Read More
Appropriately selected and applied, conformal coatings provide essential working protection for printed circuit boards (PCBs). However, removal of conformal coatings is necessary if the wrong coating material is selected relative to the PCB’s functional requirements, inadequately supporting its operating environment. Poor coating application can trigger failure mechanisms within the assembly, also calling for its removal and re-application.Read More
Printed circuit boards (PCBs) electrically connect and power all but the simplest electronic products. To function as designed, PCBs and their components – capacitors, resistors, etc. – require protection against operating problems caused by corrosive liquids, dust, physical shock, temperature extremes and, in the case of medical implants, bodily fluids. Conformal coatings are applied over PCBs to safeguard mechanisms and maintain functionality.Read More
Ruggedized products are conceived for use in severe conditions, environments where excessive moisture or dryness, extreme temperatures, high levels of vibration, wind, or lack of atmosphere are the rule. Internal components of these specialized products require the same degree of ruggedization as exteriors.
Parylene's benefits as a conformal coating are well known. It resists heat, cold, moisture, and pressure; salt spray, electricity, and solvents can't permeate it. And while these attributes of parylene contribute to the conformal coating's appeal, they also present distinct challenges, particularly in regards to parylene removal, rework, and repair.
More and more, cars aren't just made of steel, aluminum, plastic and silicon. Parylene is becoming one of the most useful tools in an automaker's arsenal. From protecting internal sensors and circuit boards to keeping LED indicator lights bright and color-accurate, Parylene conformal coatings are an important part of protecting today's sensitive automotive electronics.
Coronary stents are tubular medical implants that serve as a scaffold to open clogged or narrowed arteries in an effort to increase blood flow and reduce the potential for adverse cardiac events such as heart attacks. And providing critical support to these support structures is parylene conformal coating.
Military and defense equipment are put to the test and subjected to uniquely harsh conditions on a daily basis. These mission-critical products must be rugged and able to withstand extreme weather and temperatures, exposed forces of gravity that are well above and beyond normal situations, and a range of contaminants such as salt, water, and fungus. Luckily, the application of a parylene conformal coating to relevant electronics can ensure that components are fit for duty in the military and defense industries.
Whether the application is a medical device, a printed circuit board (PCB), or a light-emitting diode (LED), a parylene conformal coating is typically applied to protect the product. Sometimes, however, the product actually has to be protected from the parylene conformal coating—or at least parts of it do.
Parylene conformal coating boasts a bevy of benefits and properties that make it an appealing choice for a variety of medical device applications. Chief among parylene’s advantages for medical applications, however, is that it meets USP Class VI and ISO 10993 biocompatibility requirements—a characteristic that is essential for many critical medical products and that other types of conformal coating sometimes lack.
Conformal Coating Selection: Weighing the Pros and Cons for Your Application
Plastics and polymers were first being produced, whether on accident or on purpose, in the early 1930s. Dupont's Teflon, or PTFE, is probably the most widely known polymer because of its uses in cooking as a non-stick coating for pots and pans. While there are lots of other polymers out there, there are only a few that have as many uses as PTFE, one of which is Parylene.
Parylene was developed by a chemist named Michael Szwarc while he was running experiments on chemical bonds between carbon and benzene rings. While heating para-xylene, he discovered a precipitate in his equipment that turned out to be small and tube-like. He correctly identified these tubes as the polymerization of p-xylene. After a brief period known as Szwarcite, Parylene soon found uses in the medical field as an excellent hydrophobic barrier, but has been found to have plenty of other uses in electronics; metal, rubber, and surface protection from corrosion and outside elements; and as a friction reducing coating especially with needles.
PTFE's discovery, on the other hand, was purely accidental. While working with gasses for refrigeration in the Dupont laboratories, Dr. Roy Plunkett thought that a canister containing TFE was not working. After cutting the canister in half, he discovered a white flake that had developed in the tank and correctly guessed that the flake was a polymer. After conducting several tests on the flakes, since TFE was widely thought to be impossible to polymerize, Plunkett discovered that it was insoluble in anything he tried, as well as being completely inert. The first applications for PTFE were on the seals for the atomic bomb, but it also worked as the nosecone for proximity bombs because it is transparent on a radar and resists electricity.
Parylene was the first vapor deposited polymer ever discovered, and because of the vapor deposits and the fact that no solvent or catalyst is used to cause the polymerization it has a one hundred percent yield, which makes it an extremely efficient polymer to manufacture. Because it is hydrophobic and biostable, parylene has been used extremely effectively as a coating for medical tools, instruments, and hoses. It's strong resistance to corrosion make it an excellent metal coating for scalpels, hypodermic needles, and other metallic tools. It also works as a micro barrier since its surface is impermeable above thicknesses of 1.4 nanometers. Its uniformity helps it adhere to sharp edges and points, again pointing to its widespread use in the medical field.
Unfortunately, because of its formation, it cannot be applied through a solvent. This means that the only way to coat an object in parylene is during the production of the polymer which occurs in a vacuum. While the object to be coated remains near room temperature, which aids in the safety of the process, and the coating is universal and uniform, it does mean that the polymer cannot be put into an aerosol can or produced en mass for consumer use.
PTFE can be made in one of two ways, each resulting in a different looking product, but by and large the same end result. With suspension, TFE is polymerized in water and results in the PTFE forming grains, whereas dispersion causes the PTFE to form as a milky paste. Both the paste and grain are processed and used to coat various products. Although PTFE itself is non-toxic, some of the byproducts of the manufacture process are toxic and at high heats the PTFE itself can emit toxic gasses.
So you'd like to know a little something about parylene conformal coating, but were afraid to ask. You need not be ashamed. The process is so fundamental to electronic manufacturing that it can very easily be taken for granted.
While parylene coating companies are not exactly on every street corner, there are certainly a lot more of them than you think! Below you will find a list of the headquarters for knownNorth American parylene coating companies. If you do not see your company listed and would like it to be, please do not hesitate to email me.
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.
Diamond-MT is proud to announce that it will be exhibiting at IPC APEX 2013 in San Diego February 19-21, 2013. Diamond-MT will be featuring its parylene coating services and conformal coating services as well as conformal coating equipment and consultation and training services.
Parylene conformal coating is a very robust coating, but sometimes it is not the right fit for a customer’s application for one reason or another. The entire conformal coating process is based on first identifying the standards to be used and customer’s protection desired. It would therefore only make sense that there are alternatives to parylene for different conformal coating demands.
Type xy conformal coating refers to parylene conformal coating. Parylene gets the type xy from its’ full name, para-xylylene. It was shortened to parylene and eventually type xy so that it could be grouped with the other conformal coatings (type ar, ur, etc.).
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.
Diamond SCH Global Conformal Coating Solution Provider exhibiting at Nepcon Shenzhen next week
Urethane conformal coating is becoming an increasingly popular conformal coating choice. However, it is not suitable for all applications. Instances where the product is going into a high vibration environment or has a high heat requirement would not ideal candidates for urethane conformal coatings.
- Printed circuit boards
- Ferrite Cores
- Metallic Blocks
- Optical lenses
- Implantable devices
- Silicon Wafers
- Motor Assemblies
- Power Supplies
- Photoelectric Cells
- Test tubes
- Fiber Optic Components
- And many 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.
A downfall for wet chemistry, liquid coatings such as silicones, acrylics, epoxy, or urethanes is that they do not meet bio-compatibility requirements and cannot be applied with precise control. On the contrary, parylene does not out-gas and is very effective against the passage of contaminants from both the body to substrate or substrate to body.
In applications that have an exposure to solvents, acrylic conformal coating is not the best choice. Acrylic conformal coating can be removed with a weaker solvent such as isopropyl alcohol or xylene. Whenever it faces even stronger solvents, it will not offer the protection that is needed, especially if your product is a mission critical device. Other coatings, such as urethane or parylene conformal coating have a far better resistance to solvents than acrylics.
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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.
Tags: parylene conformal coating, parylene coating process, Diamond-MT, conformal coating, silicone conformal coating, conformal coatings, LED conformal coating, Automotive conformal coatings, Medical conformal coatings, conformal coating standards
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.
WHAT IS CONFORMAL COATING
Conformal coating is a protective non conductive dielectric layer that is applied to protect the assembly from damage due to contamination, salt spray, moisture, fungus, dust and corrosion caused by harsh or extreme environments.
ARE THERE DIFFERENT TYPES OF CONFORMAL COATING?
There are 5 different mediums for conformal coating:
- Acrylic Resin
- Urethane Resin
- Epoxy Resin
- Urethane Resin
WHAT ARE THE BENEFITS OF EACH TYPE OF CONFORMAL COATING?
- Parylene (Type XY)
- Acrylic Resin (Type AR)
- Epoxy (Type ER)
- Polyurethane (Type UR)
- Silicone (Type SR)