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Parylene C Datasheet (PDF Download) – Properties Explained

Posted on August 20th, 2021 by

Parylene conformal coatings come in various types, including Parylene C, Parylene N, and Parylene F (VT-4), and have decades of trusted performance in critical industries and applications. The coating is often superior in barrier properties, uniform coverage, and performance with less stress on mechanical structures, as a Parylene datasheet indicates.

Parylene coatings are comparably thinner than conventional conformal coatings and add virtually no weight to components and products. Parylene’s coating thickness can pass tests such as IPC CC-830C at 50% of the film thickness of other conformal coating materials.

Parylene coatings are unique in their ability to be polymerized and deposited by chemical vapor deposition (the Parylene coating process) onto components maintained at room temperature. As a result, the coatings are high purity, free of defects and pinholes, and ideal for meeting many electronic product design reliability requirements.

Parylene C is highly resistant to moisture, vapor, corrosive gasses, and various chemicals. Because of these strong anti-corrosion properties and a valuable combination of properties for most types of applications, Parylene C is used for most products that need a conformal coating for protection.

To see the specific properties of Parylene C, you can download HZO’s Parylene datasheet below, under the column of HZO Guardian Plus™, our Parylene C offering. For reference, HZO Guardian Zero™ is our Parylene N coating solution, suitable for halogen-free applications.

Parylene Datasheet

 

Download HZO’s Parylene datasheet

 

For reference, a short description of each category property in the Parylene datasheet is provided, and some descriptions of tests used to acquire data as well as explanations as to why some data points might be vital for your application.

Parylene C Physical and Mechanical Properties

 

Parylene is a crystalline polymer that results in generally high mechanical strength. Compared to other polymer coatings, it has a relatively high tensile and yield strength, and wear resistance is substantial. An explanation for some Parylene datasheet properties is below.

 

Parylene C Young’s Modulus

 

Young’s modulus is a mechanical property that measures the stiffness of a solid material. Young’s modulus is the elongation of a material under unit stress when the deformation is elastic.

The image below depicts an example stress-strain curve which shows the change in stress as strain increases and identifies the Young’s modulus and Tensile strength

Young’s modulus is the slope of the linear part of the stress-strain curve for a material under tension or compression. In other words, the strain will be proportional to stress. There is no permanent deformation either. The material will behave like a spring and return to its original dimension on the removal of load.

Tensile strength is is the maximum stress a material can withstand. Meanwhile, Elongation to Break is the ratio between changed length and initial length after breakage of test specimen.

Parylene Young's Modulus

Image Source: https://www.thefabricator.com/thefabricator/article/metalsmaterials/the-differences-between-stiffness-and-strength-in-metal

The table below shows values for Young’s Modulus and Tensile Strength for Parylene C and N and polyester and polyamide.

Table 1: Young’s Modulus and Tensile Strength for Parylene C and N and Polyester and Polyamide

Material Young’s Modulus Tensile Strength
Polyester 7.1×105 psi MD 29,000 psi MD
Polymide 3.6×105 psi ~33,500 psi
Parylene C 4.6×105 psi 10,153 psi
Parylene N 3.5×105 psi 6,526 psi

 

Parylene C Electrical Properties

 

Parylene doesn’t conduct electricity, an essential trait for a film that coats and separates conductive areas on electronics. As the Parylene datasheet indicates, it is a superior electrical insulator (dielectric) coating since it coats every surface on a product with uniform thickness. Although conformal coatings aren’t meant to be used as the primary means of electrical insulation, they can isolate electrical ground from active traces and supplement other insulation forms. The lack of pinholes and other point defects helps Parylene prevent arcing.

A coating with variable thicknesses on an electronics assembly running at high voltage may have a greater risk of failure if the device is operating near the dielectric breakdown voltage of the coating. At the breakdown voltage, the coating essentially undergoes a complete failure, and any insulative properties are left negligible or lost entirely.

An example of how Parylene deposits is depicted below:

Parylene Deposition

Courtesy of CALCE, University of Maryland

Though defined by its fundamental composition, the insulating properties of a Parylene coating increase with thickness. This means that by selecting a specific Parylene thickness, you can fine-tune electricity-blocking properties. Since each Parylene type has different dielectric properties, there’s a suitable parylene for virtually every application.

 

Parylene C Dissipation Factor

 

Dissipation factor is defined as the reciprocal of the ratio between the insulating materials capacitive reactance to its resistance (Equivalent Series Resistance or ESR) at a specified frequency.

This property measures electrical energy lost and absorbed (power dissipation) when an electrical current is applied to an insulating material. Much of the absorbed energy is dissipated as heat—the lower the dissipation factor, the more efficient the insulator system. Dissipation factor is an essential property because it can be used to maximize power delivery.

 

Parylene C Dielectric Strength

 

Dielectric strength is defined as the maximum voltage required to produce a dielectric breakdown through the material and is expressed as Volts per unit thickness. The image below shows that the original dielectric material as an insulator becomes a conductor because the dielectric material passes the maximum voltage and produces a dielectric breakdown.

Parylene Dielectric Strength
Dielectric strength is important for higher voltage design because it prevents arcing and protects against high voltage from static electricity. Please refer to the Parylene datasheet to see the values for this property.

 

Read more about Parylene’s dielectric strength

 

Parylene C Dielectric Constant

 

Dielectric constant is the ratio of permittivity of a substance to the permittivity of free space.

Dielectric Constant (k) = ε / ε0

Parylene Dielectric Constant

A sample is placed between two metallic plates, and capacitance is measured to obtain these values. A second run is measured without the specimen between the two electrodes. Dielectric constant is the ratio of these two values, and a low dielectric constant is essential for rapid signal propagation.

 

Parylene C Thermal Properties

 

Parylene coatings have temperature limits that, when reached, shorten the coating’s usefulness. You will need to know your expectations and/or specifications for the product’s end-use environment if you need to mitigate risks associated with high-temperature applications. The temperature stability values for the parylenes are collected in the table below and are based on industry literature.

Table 2: Parylene Thermal Properties

Parylene Type Long-Term Temperature Limit (°C)

Duration=~10+ Years

Short-Term Temperature Limit (°C)

Duration=~1 Month

Melting Point Temperature (Tm)
Parylene N 60 96 420
Parylene C 80 115 290

Fortunately, the Parylene c melting temperature is high, at 290 °C. Parylene N maintains performance through temperatures even more extreme.

 

Read more about Parylene and heat dissipation

 

Read more about Parylene performance in extreme temperatures

 

Parylene C Barrier Properties

 

Parylenes are hydrophobic, ultrathin, lightweight, and highly conformal, wrapping around every edge available, where the coating deposits the same thickness around the components they coat. The vapor phase coating process leads to pinhole-free coatings that are also free from defects. In addition, the coatings trap and immobilize any particles that may be present on substrates.

The polymer chains pack tightly against one another, making Parylene resistant to chemicals passing through the coating and reacting with the coating itself. Parylene is impervious to moisture and insoluble in chemicals found in most end-user and industrial environments. The coating also does a good job of blocking gases that can lead to corrosion of the coated object.

The Parylenes provide an excellent physical barrier that protects the underlying objects, especially electronics, from external contamination and electrical shorting. As a physical barrier, Parylene protects from various types of problematic contamination, such as dust, foreign object debris (FOD), metal filings, and airborne salts.

Parylene C has the best barrier properties, as indicated on the Parylene datasheet, including preventing both gas and water vapor penetration. The table below compares the Gas Permeability and WVTR of Parylene with other conformal coating materials.

Table 3: Barrier Properties of Conformal Coatings

Polymer Gas Permeability at 25 °C, (cc·mm)/(m2·day·atm) WVTR,(g·mm)/(m2·day)
N2 O2 CO2 H2 H2S SO2 CI2
Parylene C 0.4 2.8 3.0 43.3 5.1 4.3 0.1 0.08
Parylene N 3.0 15.4 84.3 212.6 313 745 29.2 0.59
Parylene F (VT-4) 16.7 0.28
Epoxy (ER) 1.6 4 3.1 43.3 0.94
Polyurethane (UR) 31.5 78.7 1,181 0.93
Silicone (SR) 19,685 118,110 17,710
Ref.: Licari, James J. Coating Materials for Electronic Applications – Polymers, Processes, Reliability, Testing. William Andrew Publishing, 2003 and various companies’ literature.

Parylene C also performs well when immersed in solutions of sodium chloride salt in water. The following table shows Parylene C’s performance compared to examples of epoxy, polyurethane, silicone, and Teflon™ coatings.

Table 4: Resistance of Different Polymers to 0.9% Saline Solution

Polymer Coating Method Layer Thickness (microns) Time Until Total Breakdown
Parylene C 60 25 > 30 d
Epoxy (ER) 80 100 ± 25 6 h
Polyurethane (UR) Dip Coating 100 ± 12.5 6 h
Silicone (SR) Dip Coating 75 ± 12.5 58 hr
Teflon Spraying 75 6 h
Ref.: Mordelt, G., Heim, P. High-Tech-Beschichtung der Zukunft, Metalloberfläche 52(5), 368 − 371 (1998).

In general, Parylene C performs extremely well as a barrier to corrosion due to the coating’s ability to minimize the influence of the factors that affect coating lifetime and performance, including the following:

  • Oxygen permeability − low oxygen permeability for a polymer coating
  • Water vapor permeability − very low WVTR for a polymer coating
  • Liquid water uptake − Parylene C absorbs very little water
  • Ionic permeability − salts have a difficult time passing through the coating
  • Coating porosity − at a thickness of just 5 to 8 microns, Parylene C forms a pinhole/pore-free coating

Watch Dr. Clancy’s webinar on proven methods of corrosion resistance

 

About HZO

HZO is a Parylene services provider focusing on driving down associated costs and increasing Parylene coating efficiency. We have built proprietary cubed chambers that can house more substrates than any other Parylene company. Our chambers are large in size, but the cubed shape allows for high loading density, increasing throughput, and scaling for high-volume applications.

We have also built equipment to automate masking and demasking to cut costs, save on labor ours, and decrease the risk of quality issues that may ensue due to manually doing these processes.

If you have downloaded the Parylene datasheet and are considering it for your project, and want an efficient partner, contact us today.

 

Mallory McGuinnessMallory McGuinness

Mallory is an electronics protection evangelist who writes content for HZO. In her free time she is reading non-fiction, and hanging out with her beta fish, King Awesome.

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