Parylene Coating Blog by Diamond-MT

A Guide to Parylene Temperatures

Posted by Sean Horn on Fri, Dec 07, 2018 @ 07:30 AM

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.  
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Tags: parylene, parylene properties, parylene temperature, parylene C, parylene f, parylene d, parylene af-4

Types of Parylene

Posted by Sean Horn on Fri, Mar 10, 2017 @ 07:34 AM

          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 with

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Tags: parylene, parylene C, parylene n, parylene f, parylene d, parylene af-4

Different Types of Parylene

Posted by Sean Horn on Fri, Oct 07, 2016 @ 07:30 AM

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.

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Tags: parylene, parylene C, parylene n, parylene f, parylene af-4, parylene applications, parylene cost

Parylene C vs Parylene F

Posted by Sean Horn on Fri, Jun 03, 2016 @ 07:30 AM

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. 

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Tags: parylene, parylene C, parylene f

Parylene Conformal Coatings and UV Light

Posted by Sean Horn on Fri, Feb 05, 2016 @ 07:54 AM

            Parylene has numerous outdoor applications.  However, a major drawback of most parylene types is limited resistance to direct contact with UV radiation.  Daylight is the most common source of UV light.  Prolonged exposure to its high energy radiation can cause objects extensive surface damage and lead to eventual malfunction of electrical light-generating assemblies within.  

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Tags: parylene, parylene for LEDs, parylene disadvantages, parylene f, parylene af-4