How Parylene Protects Electronics in Harsh and Hostile Environments

Parylene comes from a series of polymers from paraxylene and is often used as a coating that safeguards electronic devices. Specifically, Parylene coating is a conformal coating applied at room temperature using a chemical vapor deposition (CVD) process. For many industries, Parylene shields electronics from contamination, corrosion and complications arising from exposure to harsh and hostile environments.

Parylene Coatings for Electronics in High-Risk Applications

There are five main types of Parylene:

1. Parylene N: This is the most basic form of Parylene. With its linear structure and high crystalline content, the chemical compound has high dielectric strength. It penetrates narrow crevices and conforms to surfaces with contoured topography.
2. Parylene C: Parylene C is the most commonly used type. It has the same structure as Parylene N with an added chlorine replacing a hydrogen atom. It has low permeability to protect against corrosive gases and moisture.
3. Parylene D: This material begins with hydrogen and carbon, the same building blocks as Parylene C, but has two chlorine groups. It provides a higher temperature range and surface resistivity.
4. Parylene HT^®: This Parylene variant is capable of high heat resistance and long-term UV stability. Parylene HT replaces the alpha hydrogen atom of the N dimer with fluorine, and it’s ideal for high-temperature environments of up to 450°C.
5. ParyFree^®: ParyFree is the newest Parylene variant. It is a halogen-free coating and combines the dielectric strength of Parylene N with the barrier properties of Parylene C.

Risks for Electronics in Adverse Conditions

For electronics, harsh and hostile environments can range from the human body to the engine of a vehicle to the depths of space — any place where challenging conditions warrant extra protection for electronic components. As so many objects and systems require electronics, it’s inevitable that many will encounter harsh environments. Common dangers to electronics include exposure to:

• Extreme temperatures and fluctuations
• Contamination from dirt or dust
• High humidity and moisture
• Excess shock or voltage
• Stress or impact damage

Benefits of Using Parylene for Electronics in Harsh Environments

Parylene coatings protect electronic devices from such risks and provide electronics in harsh environments with numerous benefits, including:

• Biocompatibility: The Food and Drug Administration (FDA) has well-documented approval for medical devices containing Parylene being placed in the human body. The coating complies with the United States Pharmacopeial (USP) XXII Class VI plastics requirements and biocompatibility rating.
• Conformity: Properly applied Parylene coating is pinhole-free with uniform controllable thickness greater than 0.5 micrometers to 1 millimeter on any surface or design.
• Durability: The formation process ensures lightweight, protective performance over time. Parylene has high-quality barrier, physical and electrical properties.
• Stability: All types of Parylene have high melting points. This substance can withstand temperatures from – 296°C to +450°C.
• Permeability: As this material is nonporous and resistant to moisture and gas, it’s difficult for foreign materials to infiltrate the surface.
• Protectability: Parylene coating penetrates spaces as narrow as 0.01 millimeter for protection on virtually any surface of a part.
• Resistibility: Parylene is unaffected by solvents, acids, chemicals and other substances and can pass a 144-hour salt-spray test.
• Versatility: A variety of industries use Parylene conformal coatings for circuit boards, medical devices and other equipment.

Industries That Use Parylene: How to Protect Electronics in Hostile Environments

Without sacrificing functionality, Parylene protects electronics in harsh environments. Various industries take advantage of Parylene conformal coating to expand the applications of their devices, including:

• Automotive: Manufacturers and mechanics use electronic devices and computer chips in vehicles. These critical components need protection from vehicle fuel and fluids like battery acid, antifreeze and oil.
• Defense and Aerospace: Military personnel and pilots operate aircraft that need stability for accessible and reliable technology. Their devices must withstand conditions with varying temperature changes, weather patterns and chemical exposures.
• Electronics: Electrical technicians and engineers place printed circuit boards (PCBs) and programmable logic controllers (PLCs) into various devices. These sensors and equipment demand safeguarding against damage from dust, dirt and water.
• LEDs: Electricians and electrical contractors use light-emitting diodes (LEDs) for energy-efficient traffic signs, billboards and other lighting options. LEDs need to handle conditions where heat, water and other factors cause harm.
• Medical: Doctors and surgeons insert medical devices into the human body. As the body resists foreign objects, medical devices must survive a hostile environment where fluids and biological factors could cause damage.
• MEMS: Many industries deal in microelectromechanical systems (MEMS) with small pieces and complex parts for consumer electronics and various applications. These devices and systems need protection from harmful environmental conditions, including temperature extremes, liquids and stiction.