Implications of Parylene Coating Thickness:Read More
Parylene Coating Blog by Diamond-MT
At Diamond MT, we offer parylene coatings of different polymeric varieties (N, C, and F) as listed in the following Table. The basic parylene molecule is the Parylene N (poly-para-xylylene) monomer. Modification of the Parylene N monomer by a functional group such as Chlorine and Fluorine leads to Parylene C (poly(2-chloro-para-xylylene)) and Parylene F, respectively. The derivatization of new varieties can be done by the addition of functional groups to Paryelene N main-chain phenyl ring and its alipRead More
A specialized chemical vapor deposition (CVD) process attaches conformal coatings composed parylene (XY) to substrates. CVD uniformly encapsulates all exposed substrate surfaces as a gaseous monomer; completely eliminating wet coatings’ liquid phase and need for post-deposition curing. Synthesizing in-process, CVD polymerization requires careful monitoring of temperature levels throughout.
Beneficial thermal properties of XY protective coatings include reliable performance through an exceptional range of temperatures. Parylene is available in variety of material formats, prominently Types C, N, F, D and AH-4. Each has a particular range of properties that determine its optimal uses. Types C and N exhibit faster deposition rates than other parylenes, making them useful for a wider range of coating functions. However, operating temperature is a significant determinant of use: Much depends on chemical composition.
- Used more frequently than other XY varietals, Parylene C is a poly-monochoro para-xylene. It is a carbon-hydrogen combination material, with one chlorine group per repeat-unit on its main-chain phenyl ring. In oxygen-dominated atmospheres, C conformal films regularly provide reliable assembly security at temperatures of 100° C (212° F/water’s boiling point) for 100,000 hours (approximately 10 years). C is suggested for use in operating environments reflecting these temperature conditions. Chemical, corrosive gas, moisture, and vapor permeability remain consistently low. C generates exceptional vacuum stability, registering only 0.12% total weight-loss (TWL) at 49.4° C/10-6 torr (1 torr = 1/760 SAP (standard atmospheric pressure, 1 mm Hg). C can also be effective at temperatures below zero, to -165º C.
- With a completely linear chemical format, Parylene N is the most naturally-occurring of the parylene series. Used less regularly than Type C, N is highly crystalline; each molecule consists of a carbon-hydrogen combination. N’s melting point of 420° C is greater than most other XY types. Vacuum stability is high, registering TWL-levels of 0.30% at 49.4° C, and 10-6 torr. These properties encourage higher temperature applications. Compared to other XY varietals, N’s low dielectric constant/dissipation values also recommend uses with assemblies and parts subjected to higher levels of unit vibration during operation. N’s electrical/physical properties are not noticeably impacted by cycling from -270º C to room temperature, adding to its versatility.
- Parylene F has fluorine atoms on its aromatic ring. Possessing aliphatic -CH2- chemistry, F’s superior thermal stability is attributed to this aliphatic C-F bond, compared to Type C’s C-C bond. Better thermal stability, and reduced electrical charge/dielectric constant expand its use for ILD (inner layer dielectric) applications, such as those for ULSI (ultra large-scale integration), where a single chip can incorporate a million or more circuit elements. F is a good choice for many microelectromechanical systems (MEMS)/nanotech (NT) solutions.
- Originating from the same monomer as Type C, Parylene D’s chemical composition contains two atoms of chlorine in place of two hydrogen atoms. Like Type C, D conformal films can perform at 134° C (273° F), dependably securing assembly performance in oxygen-dominated environs for 10 years, at a constant 100° C. Parylene F resists higher operating temperatures and UV light better than C or N.
- Parylene AF-4’s melting point is greater than 500° C. It survives at higher temperatures/UV-exposure better than other parylenes for long durations because it possesses CF2 units, situated between its polymer-chain rings.
Accidentally discovered in 1947, by chemist Michael Szwarc, the polymer parylene originally bore his name, and was known for a brief period known as Szwarcite. Working to thermally decompose the solvent p-xylene at temperatures exceeding 1000 °C, Szwarc identified the monomer para-xylylene di-iodide as the only product resulting when para-xylylene was reacted with iodine.Read More
Perhaps the most reliable of the conformal coatings, parylene (para-xylylene di-iodide) is also one of the more expensive coating options. Production costs typically encompass three primary expense categories -- raw materials, labor, and lot volume. Of the three, labor expenses are generally the most costly, but raw materials can add significantly to production overhead; materials’ costs can be largely attributed to the raw parylene dimer required to make conformal coatings.Read More
Applied in a gaseous form to component surfaces through a chemical vapor deposition (CVD) process, parylene (Poly-para-xylylene) films protect printed circuit boards (PCBs) and similar electrical assemblies. Gaseous CVD application supports efficient coating of complex component surfaces characterized by crevices, exposed internal areas, or sharp edges. Depending on the specific use, parylene conformal coatings can be effective in the range of 0.1 - 76 microns' thickness, far finer than competing coating materials. Equally as strong, adaptable and versatile parylene protects substrates withRead More
Parylene Varietals: Matching Material to Purpose
A common generic name for Poly-para-xylylene, parylene forms a protective plastic film when applied to substrate surfaces. Application is achieved through a chemical vapor deposition (CVD) process in a vacuum, as a gas to targeted substrate surfaces.Read More
Parylene C is the most widely used parylene type for conformal coatings. It is classified as a poly-monochoro para-xylene, produced from dimer material, with one chlorine group per repeat unit on its main-chain phenyl ring. As a conformal coating, Type C can be deposited at room temperature via CVD. The resulting film exhibits low chemical, moisture, and vapor permeability, making it particularly useful where protection is needed from corrosive gases. C’s alliance of electrical and physical properties distinguish it uses from those Parylene F, a consequence of their different chemical composition; F has a fluorine atom on its benzene ring, in contrast to C’s chlorine atom.Read More
In the course of our business applying parylene to a range of different products, our clients ask many questions. They also have a few consistent misconceptions. Here are the five biggest ones -- and the facts to clear things up.Read More