Knowledge Base Articles

About Parylene What is Parylene? Common Applications Parylene Benefits Deposition Process Coating Process Cost Drivers Parylene Types Parylene Properties Electrical Properties Chemical Properties Mechanical Properties Thermal Properties

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Parylene Properties

What makes parylene different?

Learn how parylene’s properties can be used to help advance technology. Compare parylene’s electrical, chemical, mechanical, and thermal properties with other conformal coatings.

Want to learn the ins and outs of parylene coating?

Check out VSi’s comprehensive eBook “The Complete Guide to Parylene Coatings.”

What you’ll learn:

  • Parylene benefits and applications
  • How the vapor deposition process works
  • Detailed material properties of parylene
  • Compare parylene to other coatings
  • Design guidelines

Electrical Properties

Parylene is a material with exceptional electrical insulation properties that is applied as a conformal thin film. This unique combination allows parylene to be used as a precision dielectric layer in a variety of applications. Parylene’s breakdown voltage is determined by the coating’s thickness. Parylene also has a low dissipation factor, and high surface and volume resistivity that remain virtually constant with changes in temperature.

parylene properties, dielectric strength, silicone, urethane, epoxies, acrylic

When compared to epoxy, silicones and urethane coatings, all parylene types have an extremely high dielectric strength. Parylene N is a unique dielectric material because of the extremely low dissipation factor which changes only slightly with frequency. The chlorine in parylene C increases the dielectric constant and dissipation factor when compared to parylene N.

Highlighted Applications:

  • Capacitors – Protection against arc-over and corona discharge.
  • Protection on electrically sensitive devices.
  • Thin dielectric layer on neural probes and neuralstimulators.
  • Semiconductor wafer-level test probes.
  • Magnets and ferrite cores.
  • A micro dielectric layer for micro transducers, MEMS, and micro-coaxial probes.

Detailed Electrical Properties

Electrical Properties
Parylene C
Parylene N
Parylene F

Dielectric Strength

Dielectric strength defines the maximum voltage required to produce a dielectric breakdown of the material. The higher the dielectric strength of a material the better its quality as an insulator.

220 V/micron at 25.4 microns
5600 V/mil at 0.001”

276 V/micron at 25.4 microns
7000 V/mil at 0.001”

276 V/micron at 25.4 microns
7000 V/mil at 0.001”

Volume Resistivity

Volume resistivity is the electrical resistance through a cube of insulating material. The higher the volume resistivity, the lower the leakage current and the less conductive the material is.

8.8×1016 ohm-cm at 23°C, 50% RH

1.4×1017 ohm-cm at 23°C, 50% RH

1.1×1017 ohm-cm at 23°C, 50% RH

Surface Resistivity

Surface resistivity is the electrical resistance of the surface of an insulator material. The higher the surface resistivity, the lower the leakage current and the less conductive the material is.

1×1014 ohms at 23°C, 50% Relative Humidity

1×1013 ohm at 23°C, 50% Relative Humidity

4.7×1017 ohm at 23°C, 50% Relative Humidity

Dielectric Constant (k)

A ratio measuring the ability of a substance to store electrical energy in an electric field.

60 Hz 3.15
1 KHz 3.10
1MHz 2.95
6 GHz 3.06 ‐ 3.10

60 Hz 2.65
1 KHz 2.65
1MHz 2.65
6 GHz 2.46 ‐ 2.54

60 Hz 2.20
1 KHz 2.25
1MHz 2.42

Dissipation Factor (tan δ)

A measure of a dielectric material’s tendency to absorb some of the AC energy from an electromagnetic (EM) field passing through the material.

60 Hz 0.020
1 KHz 0.019
1MHz 0.0136
GHz 0.0002 ‐ 0.0010

60 Hz 0.0002
1 KHz 0.0002
1MHz 0.00066
GHz 0.0021 ‐ 0.0028

60 Hz 0.0002
1 KHz 0.0002
1MHz 0.008

Chemical and Barrier Properties

Parylene is an extremely effective moisture and chemical barrier layer that can be used to protect materials from an incompatible environment. VSI is able to encapsulate medical devices, electronics and oxidative materials from their environment with a very thin and conformal parylene layer. Parylene coatings waterproof electronics because of their complete uniformity.

parylene moisture vapor transmission; parylene properties

Parylene type C is typically selected as a barrier layer because the chemical structure allows for the best barrier properties and it has a faster deposition rate. Because parylene is biocompatible and implantable, it has a long history of use examples in medical devices. A layer of parylene can be used to create military-grade protection that is used to waterproof and ruggedize electronics for industrial and consumer products. Parylene also has excellent chemical resistance. It is resistant to almost every solvent, acid and alkaline chemistry commonly used. This allows parylene to be used to protect parts that will encounter harsh chemical environments.

Highlighted Applications:

  • Stents, defibrillators, pacemakers and other devices permanently implanted into the body.
  • Cochlear and intraocular implants.
  • Printed Circuit Boards (PCB) and flex-circuits.
  • Protection for plastic and elastomeric materials from harmful environments.
  • Protective layer for 3D printed parts to improve compatibility with chemicals.
  • Power supplies and sensors.
  • Electronics for space and aerospace applications.
  • Corrosion protection for metals.

Gas Permeability

Gas permeability is a material property that defines the penetration of a gas through a solid membrane. A low gas permeability rate is very desirable for coatings that need to seal and encapsulate a part. Compared to epoxies, urethanes and silicones, parylene has considerably better gas permeability. The table below shows the gas permeability of parylene for common gases. Gas permeability is expressed in the following units: (amount of gas)(thickness of membrane) / (membrane area) (time)(differential pressure of gas).

Gas
Parylene C
Parylene N
Parylene F

Nitrogen (N2)

0.4 at 25°C, (cc*mm)/(m2*day*atm)

3.0 at 25°C, (cc*mm)/(m2*day*atm)

–

Oxygen (O2)

2.8 at 25°C, (cc*mm)/(m2*day*atm)

15.4 at 25°C, (cc*mm)/(m2*day*atm)

16.7 at 25°C, (cc*mm)/(m2*day*atm)

Carbon Dioxide (CO2)

3.0 at 25°C, (cc*mm)/(m2*day*atm)

84.3 at 25°C, (cc*mm)/(m2*day*atm)

–

Hydrogen (H2)

43.3 at 25°C, (cc*mm)/(m2*day*atm)

212.6 at 25°C, (cc*mm)/(m2*day*atm)

–

Chemical Resistance

Parylene is insoluble in all common solvents, acids and alkalis used in processing and cleaning electronics. The table below reports testing that was performed on parylene test strips 12-35 microns thick. The test strips were immersed in test liquids until equilibrium swelling was reached. The percent thickness change was either due to swelling or the solvent content of the film after surface drying. In no case was there a decrease in the original film thickness. After the strips dried, they all returned to their original thickness.

This testing demonstrates how parylene reacts to different chemicals. The minimal swelling and return to original thickness indicate parylene’s resistance to the chemicals listed below.

Inorganic Reagents
Parylene C % Swelling
Parylene N % Swelling

10% Hydrochloric

(Non-Oxidizing Acid)

0.0% at 25°C
0.0% at 75°C

0.0% at 25°C
0.0% at 75°C

37% Hydrochloric

(Non-Oxidizing Acid)

0.0% at 25°C
4.1% at 75°C

0.2% at 25°C
2.3% at 75°C

10% Sulfuric

(Non-Oxidizing Acid)

0.3% at 25°C
0.2% at 75°C

0.1% at 25°C
0.2% at 75°C

95-98% Sulfuric

(Non-Oxidizing Acid)

0.4% at 25°C
5.1% at 75°C

0.2% at 25°C
5.3% at 75°C

10% Nitric

(Oxidizing Acid)

0.1% at 25°C
0.1% at 75°C

0.1% at 25°C
0.2% at 75°C

71% Nitric

(Oxidizing Acid)

0.2% at 25°C
1.85% at 75°C

0.2% at 25°C
Became brittle at 75°C

10% Chromic

(Oxidizing Acid)

0.1% at 25°C
0.0% at 75°C

0.1% at 25°C
1.2% at 75°C

74% Chromic

(Oxidizing Acid)

0.0% at 25°C
7.8% at 75°C

0.3% at 25°C
8.2% at 75°C

10% Sodium Hydroxide

(Base)

0.0% at 25°C
0.5% at 75°C

0.1% at 25°C
0.0% at 75°C

10% Ammonium Hydroxide

(Base)

0.2% at 25°C
0.4% at 75°C

0.3% at 25°C
0.4% at 75°C

100% De-Ionized Water

(Inert)

0.0% at 25°C
0.0% at 75°C

0.0% at 25°C
0.0% at 75°C

Organic Reagents
Parylene C % Swelling
Parylene N % Swelling

Isopropyl

(Alcohol)

0.1% at 25°C
0.2% at 75°C

0.3% at 25°C
0.3% at 75°C

Iso-Octane

(Aliphatic Hydrocarbon)

0.4% at 25°C
0.5% at 75°C

0.2% at 25°C
0.3% at 75°C

Pyridene

(Amine)

0.5% at 25°C
0.7% at 75°C

0.2% at 25°C
0.4% at 75°C

Xylene

(mixed)

2.3% at 25°C
3.3% at 75°C

1.4% at 25°C
2.1% at 75°C

Trichloroethylene

(TCE)

0.8% at 25°C
0.9% at 75°C

0.5% at 25°C
0.7% at 75°C

Chlorobenzene

(Chlorinated Aromatic)

1.5% at 25°C
2.0% at 75°C

1.1% at 25°C
1.7% at 75°C

O-Dichlorobenzene

(Chlorinated Aromatic)

3.0% at 25°C
1.4% at 75°C

0.2% at 25°C
0.3% at 75°C

Trichlorotrifluoroethane

(Fluorocarbon)

0.2% at 25°C
0.3% at 75°C

0.2% at 25°C
0.2% at 75°C

Acetone

(Ketone)

0.9% at 25°C
0.9% at 75°C

0.3% at 25°C
0.4% at 75°C

2,4-Pentanedione

(Ketone)

1.2% at 25°C
1.8% at 75°C

0.6% at 25°C
0.7% at 75°C

Mechanical Parylene Properties

Parylene is a crystalline polymer which results in generally high mechanical strength. Parylene has a relatively high tensile and yield strength compared to other polymer coatings. Parylene has a hardness higher than polyurethane and epoxy. However, it has the approximate hardness of human skin. Although parylene’s wear resistance is substantial, it isn’t recommended to be used in applications with repeated abrasion with harder materials.

parylene coefficient of friction; parylene properties

Detailed Mechanical Properties

Mechanical Properties
Parylene C
Parylene N
Parylene F

Young’s Modulus

The force is needed to stretch or compress a material. Stress/Strain.

2.8 GPa
400,000 psi

2.4 GPa
350,000 psi

3.0 GPa
435,000 psi

Tensile Strength

The force required to pull a material to point where it will break.

68.9 MPa
10,000 psi

48.3 MPa
7,000 psi

55 MPa
7,800 psi

Yield Strength

The stress at which permanent (plastic) deformation occurs.

55.2 MPa
8,000 psi

42.1 MPa
6,100 psi

52 MPa
7,600 psi

% Elongation to Break

The ratio between the change in length and initial length that causes the material to break.

20-200%

20-250%

10-50%

Elongation at Yield

The ratio between the increased length and initial length at the yield point.

2.9%

2.5%

2.4%

Density

The mass per unit volume.

1.289 g/cm3
80.5 lb/ft3

1.11 g/cm3
69.3 lb/ft3

1.652 g/cm3
103.1 lb/ft3

Hardness (Rockwell)

Rockwell hardness is a measure of the indentation resistance of a material. Testing is performed forcing a steel ball indentor into the surface of a material. The R scales tests between 10 and 60 kg.

R80

R85

R80

Coefficient of Friction

The coefficient of friction is the minimum force required to get an object to slide on a surface, divided by the forces pressing them together. It is important to note that the difference in static and dynamic coefficient of friction is undetectable for parylene.

0.29 static and dynamic

0.25 static and dynamic

0.35 static
0.39 dynamic

Wear and Abrasion

Parylene wear and abrasion values compared to urethanes, epoxies, high impact PVC and Teflon are shown below. The data comes from a Taber abraser and wear tester. This data can be used to help designers understand how parylene will work in applications where friction with parylene is expected. The data was obtained using a C5-17 Calibrase wheel with 100 grams of weight.

parylene properties; parylene wear index

Highlighted Applications:

  • Dry lubricity for catheters and guidewires.
  • Dry lubricity for silicone parts and silicone cables.
  • Dry lubricity for o-rings, seals and gaskets.
  • Encapsulating circuit boards and electronics to reduce the effects of vibration.
  • Add rigidity to a fragile component.

Thermal Parylene Properties

Parylene, like all polymers, has an ideal temperature operating range which is dependent on the application and environment. At temperatures outside the ideal temperature operating range, parylene will start to become translucent or yellow and will become brittle.

continuous service temperature for parylene; parylene properties

The operating temperature range increases significantly if parylene can be used in the absence of air or in inert atmospheres. In an oxygen-free environment, oxidative degeneration does not take place. Degradation is due primarily to the thermal cleavage of carbon-carbon bonds.

If high temperature is a concern, VSI recommends every application is looked at and tested individually. Each parylene’s melting temperature type defines an upper limit. The table below gives guidelines for 1,000- hour use and continuous use to demonstrate parylene melting points.

Detailed Specifications

Thermal Property

Parylene C

Parylene N

Parylene F

Melting Point

290ºC
554ºF

420ºC
788ºF

435ºC
815ºF

Short-term Service Temperature

Recommended maximum temperature for 1,000 hours of use.

115ºC [239ºF] in oxygen environments
350ºC [662ºF] in inert environments

95ºC [203ºF] in oxygen environments
265ºC [509ºF] in inert environments

250ºC [482ºF] in oxygen environments

Continuous Service Temperature

Allowable temperature exposure for 10 years service life.

80ºC [176ºF] in oxygen environments
230ºC [446ºF]in inert environments

60ºC [140ºF] in oxygen environments
220ºC [428ºF] in inert environments

200ºC [392ºF] in oxygen environments

Linear Coefficient of Thermal Expansion

The relative change in length per degree temperature change.

35 ppm/ºC at 25ºC

69 ppm/ºC at 25ºC

45 ppm/ºC at 25ºC

Thermal Conductivity (k)

Thermal conductivity is a material property describing the ability to conduct heat.

0.084 (W/(m*K) at 25ºC

0.126 (W/(m*K) at 25ºC

0.1 (W/(m*K) at 25ºC

Specific Heat (c)

The specific heat is the amount of heat per unit mass required to raise the temperature by one degree Celsius.

0.17 cal/(g* ºC)
at 20º C

0.20 cal/(g* ºC)
at 20º C

1.652 g/cm3
103.1 lb/ft3

Highlighted Applications:

  • Protect sensors in a high-temperature environment
  • Autoclavable barrier layer to protect electronics during sterilization.
  • Conformal coating for cryogenic applications.

Get The Complete Guide to Parylene Coatings.

A comprehensive guidebook with detailed information on parylene properties and the coating process. Includes a full comparison to other conformal coatings.