Parylene Coating Blog by Diamond-MT

Effects of Adhesion Promotion on Sensors

Posted by Sean Horn on Fri, Oct 26, 2018 @ 07:30 AM

Sensors measure specific aspects of data-driven technology.  Included are such performance properties as acceleration, fluidity, humidity/temperature, position, pressure or vibration.  Sensors collect data  and respond with feedback for a multitude of electronic devices utilizing printed circuit boards (PCBs) and related sensitive electronics.  They have been successfully adapted for use across a wide range of applications, including aerospace/military, appliance, automotive, communications, consumer, industrial, medical and transportation uses.  

PCBs and the larger devices they power often need to function in harsh operating environments.  Conformal coatings -- liquid acrylic, epoxy, silicone and urethane resins, and chemical vapor-deposited (CVD) parylene – provide PCBs and similar electronics excellent barrier, dielectric and insulative protection through most performance conditions, sustaining their expected utility.  Substrate adhesion is necessary to conformal film reliability; coatings do not work if they delaminate or otherwise disengage from the components they are applied to protect. 

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Tags: parylene adhesion, sensors, parylene inpsection

Repairing Parylene Delamination

Posted by Sean Horn on Fri, Apr 21, 2017 @ 07:37 AM

Applied as a conformal coating through a unique chemical vapor deposition (CVD) process, parylene provides micron-thin, resilient barrier protection for an exceptional range of electrical assemblies.  In comparison to liquid coatings -- acrylic, epoxy, silicon, urethane -- parylene is the coating-of-choice for protecting printed circuits boards (PCBs) and medical devices.  It’s films negate the impact of gravity and surface tension during the coating process; . 

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Tags: parylene, parylene adhesion, parylene disadvantages, parylene delamination, parylene issues

Five Common Causes of Parylene Failure

Posted by Sean Horn on Fri, Aug 05, 2016 @ 08:00 AM

Parylene Conformal Coatings

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Tags: parylene, parylene adhesion, parylene disadvantages, medical device coating, parylene delamination, parylene issues

The Impact of Temperature on Parylene Adhesion

Posted by Sean Horn on Fri, May 20, 2016 @ 07:30 AM

Basic Thermal Properties of Parylene Conformal Coatings 

CVD-generated parylene combines high thermal stability with a low dielectric constant, minimal moisture absorption, and other advantageous properties which sustain its adhesion to substrate surfaces.  Among the most beneficial of the parylenes’ thermal properties is their ability to function at an exceptional range of temperatures.  Depending on the parylene type, they are operative at temperatures as low as -271º C, and as high as 450º C, representing an ability to perform within a span of 721º C.  

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Tags: parylene, parylene adhesion, silane 1a74

How to Test Parylene Adhesion

Posted by Sean Horn on Fri, May 06, 2016 @ 07:30 AM

The Need for Adhesion Testing

Applied mechanical processes stimulate the binding force between surface molecules required for parylene adhesion to substrates, which is essential to both good parylene performance and assembly/component functionality.  The emergence of conditions characterized by non-adherence and delamination squander parylene’s typically exceptional substrate protection against chemical attack, corrosion and moisture, as well as its superior dielectric insulation (er = 3.1).  

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Tags: parylene, parylene adhesion, parylene adhesion testing

How to Improve Parylene Adhesion to Noble Metals

Posted by Sean Horn on Fri, Apr 22, 2016 @ 07:00 AM

Characteristics of Noble Metals

Selecting the appropriate pre-treatment procedures is a key factor to this success of parylene adhesion to any substance.  Procedures vary quite considerably, according to the materials designated for conformal coating and substrate.  Chemically inert surfaces like gold, silver and other noble metals, and nonpolar thermoplastics such as parylene, are extremely difficult to bond; they require additional surface treatments besides cleaning.  

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Tags: parylene, parylene adhesion, silane 1a74

Does Parylene Adhere Chemically?

Posted by Sean Horn on Fri, Apr 01, 2016 @ 08:10 AM

            Parylene only adheres to substrates mechanically, and this can require assistance from additive substances; parylene’s chemically-based adherence is nonexistent.  Adhesion is a consequence of molecular attraction stimulating the surface unification of two dissimilar substances; their joining creates a significant physical bond between them.  Of the two primary types of adhesion, chemical adhesion results when a compound joins with another, because they share sufficient mutual chemical interaction to form a bond with each other.  Because parylene is chemically inert, chemical adhesion is impossible; it adheres using the other method -- mechanical adhesion.  Applied mechanical processes can stimulate this binding force between surface molecules.   

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Tags: parylene, parylene process, parylene adhesion

Surface Treatments Prior to Parylene Coating

Posted by Sean Horn on Fri, Mar 11, 2016 @ 08:07 AM

Pre-coating Essentials

Poor parylene adhesion negates many of the coating’s most-valued functional properties, including dielectric strength, and resistance to the effects of chemicals, corrosive agents, and moisture.  Surface treatments that amplify the interface adhesion between the deposited parylene and the coated substrate are therefore highly desirable.  These treatments entail depositing parylene on a clean hydrophobic surface before its chemical vapor deposition (CVD) process is enacted.

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Tags: parylene, parylene masking, parylene adhesion, silane 1a74, surface prep

Causes of Parylene Delamination

Posted by Sean Horn on Fri, Feb 26, 2016 @ 08:39 AM

Delamination Problems of Parylene Conformal Coatings

Providing a uniform and pinhole-free substrate coating that is ultra-thin, lightweight and durable, parylene coatings completely conform to targeted components and assemblies.  Parylene CVD generates a structurally continuous film that, with appropriate pre-treatment, penetrates deep within substrate surfaces, rather than simply attaching themselves to substrates as liquid-application coatings do.  These provide effective, dielectrically efficient safeguards with coatings as thin as a fraction of a micrometer.   Parylene is chemically and biologically inert and stable, an excellent barrier material to abrasive chemicals, bodily fluids, solvents, liquid water and water vapor.

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Tags: parylene, parylene adhesion, parylene delamination, parylene issues

What Is the Proper Adhesion Test for Conformal Coating?

Posted by Sean Horn on Fri, Jan 29, 2016 @ 08:09 AM

You've done your research, chosen a conformal coating provider, and coated your device. Now you want to know if the coating properly adhered.

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Tags: conformal coating, parylene adhesion, conformal coating adhesion, adhesion testing

Parylene and A-174 Silane

Posted by Sean Horn on Fri, Jan 15, 2016 @ 07:41 AM

Improving Parylene Adhesion

Parylene provides an entirely conformal, durable, pinhole-free substrate coating of extreme utility for an exceptional range of materials, products and purposes. Despite its many advantages, parylene's chemical structure can actually interfere with the reliable interface adhesion required for optimal performance. The chemical vapor deposition (CVD) process that generates so many of parylene's benefits also nullifies chemically-based substrate adhesion; only mechanical adhesion is possible.

Implementing optimal adhesion can require surface modification via application of adhesion promoting agents or methods. The materials and processes used for these purposes are largely dependent on the substrate surface and component's specific operational environments and functions. Although most adhesion promotion methods are used prior to CVD, several can be integrated into the coating-process itself, Among the methods of adhesion promotion used with parylene are:

  • Thorough surface-cleaning, which stimulates enhanced adhesion by eliminating accumulated substrate contaminants whose presence can diminish overall coating quality.
  • Heat-treating. for three hours at temperatures of 140°C, beneficially activates longer-term adhesion and insulation.
  • Active, wired devices profit from bilayer component-encapsulation processes.

While these techniques have their uses for parylene adhesion promotion, the chemical monolayer Silane A-174 (3-Methacryloxypropyltrimethoxysilane - C10H20O5Si) is used most frequently to modify substrate surfaces and improve parylene adhesion.

The Uses of Silane A-174

Silane A-174's value as an adhesion promoting agent stems largely from its versatility. It can be successfully applied to substrate materials like elastomer, glass, metal, paper, plastic or quartz, among a wide range of surface substances. The A-174 silane molecule develops a robust chemical bond with the substrate, facilitating the improved surface adhesion capacity of parylene’s mechanical property. Optimal parylene adhesion is commonly achieved by a treatment with A-174 silane prior to initiating the CVD process. However, regarding appropriate procedural scheduling:

  • it is recommended that A-174's application be completed after any necessary masking operations have been finished;
  • depending on substrate materials, manual spray, soaking, or vapor phase silane processing techniques may be used to apply A-174.

Download our guide  on Parylene 101

Process Balance

While the silane promotes adhesion, the parylene assures protection. Thus, appropriately proportional intermixtures of silane A-174 and parylene need to be used, in all cases. Corrosion-resistance can be diminished where the relationship between parylene and silane is inexact, causing part and function deterioration from both beneath- and external to the conformal covering. This is especially the case with medical implants, where reliable component function is mandatory, despite being subjected to persistent exposure to often harsh bodily fluids.

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Tags: parylene, parylene adhesion, silane 1a74

Common Parylene Defects

Posted by Sean Horn on Fri, Sep 25, 2015 @ 10:26 AM

While parylene is an extremely effective conformal coating, its benefits only come into play when it is properly applied. When parylene is either applied incorrectly or is deposited on a surface that is not prepared for adhesion, the coating can become compromised. Luckily, common parylene defects can be identified, planned for and mitigated through proper procedures.

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Tags: parylene, parylene adhesion, parylene disadvantages

Seven Key Parylene Challenges

Posted by Sean Horn on Fri, Aug 14, 2015 @ 08:14 AM

Recognition of parylene's excellence as a conformal coating for many product uses has grown along with its application.  However, issues of barrier failure, current leakage, poor processing, and cost limit its further development and use.

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Tags: parylene, parylene adhesion, parylene disadvantages

Parylene Adhesion & Cleaning

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

Parylene Surface Protection

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Tags: parylene, parylene adhesion

5 Common Misconceptions of Parylene

Posted by Sean Horn on Wed, Mar 11, 2015 @ 09:11 AM

In the course of our business applying parylene to a range of different products, our clients ask many questions. They also have a few consistent misconceptions. Here are the five biggest ones -- and the facts to clear things up.

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Tags: parylene, parylene C, parylene adhesion, parylene n

Parylene Adhesion to Noble Metals

Posted by Sean Horn on Wed, Dec 04, 2013 @ 05:17 PM

Parylene adhesion can be tricky to manage. Unlike other coatings that adhere to the surfaces they coat, parylene sticks to itself. This can cause trouble when it needs to be applied to smooth surfaces, like areas made of stainless steel or noble metals like gold or silver. However, since parylene has so many other advantages, it's worth looking into methods to improve adhesion. You can use the product; you just might need an extra step.

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Tags: parylene, parylene adhesion, parylene disadvantages

Managing Parylene Adhesion

Posted by Sean Horn on Tue, Sep 10, 2013 @ 10:39 AM

It is imperative to obtain proper adhesion of the coating to the substrate in order to truly reap the benefits of parylene conformal coating. Poor parylene adhesion, after all, can negate some of parylene's most-prized properties, including corrosion resistance, chemical resistance, moisture resistance, and dielectric strength. So, it's in an engineer's best interest to understand the importance of parylene adhesion and how to obtain it.

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Tags: parylene, parylene coating process, parylene adhesion

Parylene Disadvantages

Posted by Sean Horn on Wed, Oct 17, 2012 @ 09:51 AM

Parylene offers the best protection against solvents of any conformal coating.  It is also brings to the table excellent moisture and gas protection, very high dielectric strength, and is bio-compatible.  Even with all of these benefits, there are still some disadvantages to using parylene versus other conformal coatings.

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Tags: parylene, parylene cost, parylene conformal coating, parylene coating process, parylene properties, parylene adhesion, parylene disadvantages

How Parylene Cost is Determined

Posted by Sean Horn on Mon, Apr 16, 2012 @ 03:34 PM

Parylene is often priced out to be one of the more expensive conformal coating options.  After a quick look at some of the cost factors, it will be easy to see why.  Three of the main factors that influence parylene cost are raw materials, labor, and lot volume. 

 Raw Materials – Parylene Dimer and Adhesion Promotion

 Parylene dimer is the raw form of parylene.  It is the solid inserted into the machine that is broken down through the deposition process.  Cost for parylene dimer can be anywhere from $200 to $5,000 per pound depending on the different type of dimer.  A typical coating run is around a pound of dimer.

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Tags: parylene, parylene cost, parylene process, parylene deposition, parylene dimer, conformal coating process, conformal coating methods, conformal coating service, parylene adhesion, parylene coating service, conformal coating costs

All about the Parylene Coating Process

Posted by Sean Horn on Tue, Apr 03, 2012 @ 11:21 AM

Parylene Coating Process – Phase 1 – Prior to Parts Arrival

 Once we receive a purchase order from a customer, all of the pertinent information such as drawings, specifications, and special instructions are given to the quality department from our marketing team to create custom work instructions for that particular part. 

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Tags: parylene, parylene process, parylene deposition, Diamond-MT, conformal coating, parylene adhesion, parylene coating service

How to Improve Parylene Adhesion

Posted by Sean Horn on Wed, Mar 28, 2012 @ 02:28 PM

How to Improve Parylene Adhesion

 Parylene, through its deposition process, does not adhere chemically, only mechanically, to any given substrate.  In order to improve parylene adhesion to its best possible levels for a wide variety of substrates, different methods of surface modification via adhesion promoters must be used.  Adhesion promotion methods are typically used prior to the actual coating process, however some can be integrated during the process itself.

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Tags: parylene, parylene process, parylene deposition, conformal coating, parylene adhesion