Parylene Coating Blog by Diamond-MT

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

PTFE and Parylene

Posted by Sean Horn on Fri, Oct 23, 2015 @ 08:12 AM

Properties of Polytetrafluoroethylene (PTFE)

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Tags: parylene, parylene properties, ptfe

Best Conformal Coating for Moisture

Posted by Sean Horn on Fri, Oct 16, 2015 @ 08:28 AM

Protective Conformal Coatings

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

Parylene Dieletric Properties

Posted by Sean Horn on Fri, Jun 05, 2015 @ 08:00 AM

 Basic Dielectrics and Conformal Coatings

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Tags: parylene, parylene properties

5 Key Properties of Parylene

Posted by Sean Horn on Tue, Jan 07, 2014 @ 09:42 AM

Since its discovery in the 1940s, Parylene has skyrocketed to prominence as an ideal conformal coating choice for a range of applications. Given its unique blend of properties, it might seem like an unparalleled conformal coating option. In many ways, it is. Here are five key properties of Parylene that differentiate it from the rest.

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Tags: parylene, parylene properties, parylene C

Parylene propels MEMS design

Posted by Sean Horn on Wed, Nov 06, 2013 @ 08:40 AM

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Tags: parylene, parylene properties, MEMS