Parylene Coating Blog by Diamond-MT

Does Parylene Get Everywhere?

Posted by Sean Horn on Fri, Apr 27, 2018 @ 07:30 AM

After pertinent research you’ve determined parylene (XY) is the best conformal film for your coating assignment.  Especially relevant were XY’s uniform protective and insulative properties, which are useful for numerous applications, ranging from printed-circuit boards (PCBs) to medical implants to military-grade purposes.  Among parylene’s other advantages are: 

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Tags: parylene properties, conformal coating inspection, parylene inpsection

Does Parylene De-Wet?

Posted by Sean Horn on Fri, Apr 20, 2018 @ 07:30 AM

Liquid conformal polymers – resins of acrylic (AR), epoxy (ER), silicone (SR) and urethane (UR) – use wet application processes to attach to substrates.  Most prominent of these are brushing the wet coating onto an assembly, dipping (immersing) the assembly in a bath of liquid coating, or spraying the conformal film onto the designated surface.  The coating materials are wet when they are applied.  If

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Tags: parylene properties, conformal coating properties, parylene inpsection

Are Parylene Noodles a Defect?

Posted by Sean Horn on Fri, Apr 06, 2018 @ 07:30 AM

Unlike liquid conformal coatings joined to substrate surfaces by wet application methods, polymeric parylene (XY) uses a unique chemical vapor deposition (CVD) process to assure adherence.  There is no intermediate liquid phase.  Rather, cross-link polymerization of powdered raw XY-dimer converts the solid to a vapor at the molecular level, polymerizing XY directly as a transparent film on assembly surfaces.

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Tags: parylene properties, conformal coating defects, parylene inpsection

Best Coating for Dielectric Strength

Posted by Sean Horn on Fri, Dec 22, 2017 @ 08:00 AM

Dielectric strength is a measurement of a conformal coating’s insulation effectiveness. The higher the numerical designation of strength, the more likely a coating is to resist dielectric breakdown -- a level of 7,000 is dielectrically stronger than 2,200. Conformal coatings with higher hydrophobic properties and lower extractible ionic impurities are less likely to attract water, rendering them less mobile, while enhancing existing dielectric strength

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Tags: parylene properties, conformal coating properties, dielectric strength

4 Aerospace Applications of Parylene

Posted by Sean Horn on Fri, Nov 03, 2017 @ 07:49 AM

Superior to liquid coatings like acrylic, epoxy, silicone and urethane, parylene conformal films offer unparalleled protection for aerospace printed circuit boards (PCBs) and related electronic assemblies. Their complete encapsulation conforms entirely to all device surfaces – flat, round, creviced or edged, while adding almost no weight to the covered device.

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Tags: parylene, parylene properties, UV light and parylene, parylene af-4, parylene for aerospace

Lubricious Coatings

Posted by Sean Horn on Fri, Jul 14, 2017 @ 07:37 AM

Contributing to good performance for internal medical appliances, lubricity is a conformal coating’s ability to lower operational friction that might retard its function and endanger patient health.  Lubricious coatings offer essential protection for appliances like cardiac-assist devices (CADs), catheters, elastomers, guidewires, and stents.  Compared to an uncoated device, lubricious films can reduce frictional forces by more than 90%, dramatically decreasing potential harm caused by excessive insertion-force or internal puncture damage.  This relative ease of use is important for implants and similar devices that require navigation throughout the patient’s vascular system or other internal structure; otherwise, patients can suffer from abrasion generated between the device surface and blood vessel walls. 

Coefficient of Surface Friction

The degree of physical resistance a device demonstrates is numerically expressed by a coating’s coefficient of friction (µ), which quantifies:

Static friction (µs) occurs when an object moves across a stationary surface; kinetic friction (µk) results for two objects simultaneously in motion, moving across each other.  Conformal coatings are used in both circumstances, especially for medical implants with moving MEMS/nano-tech components.

Where higher-level surface lubricity is sought, lower µ-values are the objective; they signify lessened frictional resistance, minimizing non-release, dry-sticking challenges that interfere with devices’ performance.  For instance, a µ-value of 1 indicates an equal quantity of force is needed to either lift an object, or slide it across a level surface; these calculations compare an object’s weight to the total force required to make it move.  Most everyday objects and materials have a coefficient between 0 and 1; values closer to 1 are not feasible for medical purposes.  For medical devices, a µ-value:

  • ranging from 0.01 to 0.1 is ideal,
  • but remains difficult to achieve
  • for application to the expansive degree of metallic and polymeric substrates used for medical appliances,
  • which require highly-specified levels of abrasion resistance and non-thrombogenic properties,
  • in addition to biocompatibility and lubricity.

Appropriate safety standards also need to be met.

Much depends on the materials comprising the touching surfaces.  Conformal coatings like Teflon (PTFE) and parylene, which provide high-level lubricity, maintain that level for a prolonged operational duration, making them very useful for specialized medical applications.

Properties of Reliable Coating Lubricity

Lubricated surfaces have lower levels of friction.  Wet hydrophilic coatings amass water as a source of lubricity, applied by liquid methods such as dipping or spraying the film substance onto substrates.  Applied to catheters or guidewires, they temporarily minimize development of thrombosis.  However, their lubricious function decreases with time, dissociating or dissolving from the matrix surface, leaving particulates in tissue or the bloodstream, endangering patient health.  Thus, they are less reliable long-term than hydrophobic coatings   

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Tags: parylene, parylene properties, Medical conformal coatings, medical device coating, lubricious coatings

Solvent Resistance of Parylene

Posted by Sean Horn on Fri, May 12, 2017 @ 07:25 AM

The parylene variants are resistant to solvents and protect substrates solvents.  This high level of security is maintained through temperatures of 150° C, seldom encountered in the actual use of PCBs or related electronics.  These properties are largely a development of the unique molecular structure of parylene polymers, rendering them:

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Tags: parylene, parylene properties, conformal coating solvents, solvents

Nano Coating vs Parylene

Posted by Sean Horn on Fri, Feb 24, 2017 @ 08:00 AM

Although its basic component is remarkably small – with 25,400,000 nanometers included in just one inch(!!) -- nanotechnology encompasses a growing, interdisciplinary field with an unlimited future.  Nanowires and nanotubes are used in transistors for printed circuit boards (PCBs) and associated electronic assemblies.  Bio-nanobatteries, capacitators, LCDs, and microprocessors represent just a few nano-applications, which include uses for aerospace, agricultural, automotive, consumer, industrial, medical, military and oceanic products. 

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Tags: parylene, parylene properties, conformal coating, parylene disadvantages, nano coating

Disadvantages of Using Parylene on Electronics

Posted by Sean Horn on Fri, Sep 23, 2016 @ 07:30 AM

Despite parylene’s numerous benefits as a conformal coating, it has several disadvantages that should be recognized before it is used.  Failure mechanisms that can emerge from parylene coatings have limited its wider scale application in comparison to liquid conformal films such as acrylic, epoxy, silicon, and urethane.  In many situations, wet coatings can provide better performance and lower cost (or both) for many applications

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Tags: parylene, parylene properties, parylene removal, parylene disadvantages, parylene issues

Parylene vs Humiseal

Posted by Sean Horn on Fri, Oct 30, 2015 @ 08:42 AM

The conformal coating process creates a protective barrier for product substrates. The type of coating material used is a consequence of several conditions:

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Tags: parylene, parylene properties, HumiSeal 1B31, HumiSeal, Humiseal 1A33