Conformal Coating & Parylene FAQs

Answers to Common Parylene & Conformal Coating Questions

Q: What are conformal coatings?

A: Conformal coatings are barrier materials typically applied in thin layers that provide chemical, mechanical, and/or electrical properties and/or protection. Typically thought of in the context of electronics, conformal coatings are also valued components of biological, medical, and industrial systems. Compare conformal coatings. 

Q: What is Parylene conformal coating?

A: Parylene is a solid state, truly conformal coating. During the coating process, it is applied as a vapor at ambient temperature, using a vacuum deposition process. Unlike liquid types of conformal coatings, ultra-thin, clear Parylene film is unique in its ability to form at a single, continuous thickness, whether on flat or planar areas, in corners, around edges, between closely spaced components or in deep crevices.  Learn about the properties of parylene. 

Q: What national/industry standards do conformal coatings meet?

A: Conformal coatings for use on printed wiring assemblies meet IPC-CC-830B and workmanship meets IPC-J-STD and IPC-A-610 standards.  Legacy programs in Aerospace, Military and Defense may still be processed using the now-obsolete MIL-I-46058C.

Q: What is UV tracer and why is it a useful inspection tool?

A: Parylene does not fluoresce. UV tracers can be added to Parylene as a level of fluorescence to make inspection easier in some applications.

Q: Can conformal coatings be removed or reworked?

A: Yes. Although Parylene cannot be removed chemically, Parylene removal can be accomplished by heat (soldering iron) or mechanical abrasion such as brushing, scraping, or micro-blasting.  More delicate or precise removal may be done by laser or plasma ablation. The standard IPC-7711C/7721C - Rework, Modification, and Repair of Electronic Assemblies provide information regarding reworking conformal coatings.  Advanced Coating provides training to customers interested in reworking Parylene.  

Q: It is easy to distinguish an uncoated UR or AR part from a coated part. The film thickness of Parylene makes it hard to tell if a part is coated or not. How does one distinguish between the coated and uncoated parts?

A: Because of how our process is designed and because tens of thousands of Parylene-coated parts pass through our hands annually, it is easy for us to know the difference. For our customers, the easiest way to determine whether a part is coated is to look for a demarcation line: the point where masked and coated areas meet. The use of magnification is helpful. 

Questions About Advanced Coating

Q: Does Advanced Coating's quality management system meet any national/international standards?

A: Yes. Advanced Coating is registered to ISO9001:2015 and AS9100 Rev D. Learn about our certifications. 

Q: My coating application is military and/or aerospace. Does Advanced Coating have experience in these fields?

A: Absolutely. Current and past Advanced Coating customers include OEMs and a wide number of Tier 1 and Tier 2 suppliers. Our applications protect guided munitions, landing gear actuators, fly-by-wire throttles and controls, communications devices, spacecraft, and deep-sea submersibles – to mention a few. See military and defense applications. 

Q: My product is ITAR controlled. Is Advanced Coating ITAR compliant?

A: Advanced Coating is ITAR registered. The registrant code is M26606.

Q: My application is both easily damaged during handling and ESD sensitive. How does Advanced Coating address these issues?

A: The safe handling of parts, the vast majority of which were not intended nor designed to be handled, is at the core of our competence. We identify and address any uniquely fragile conditions during the quote process. Our standard handling methods are designed to successfully process PWBs without damage and our ESD program complies with MIL-STD-1686 & ANSI/ESD S20.20 Standards.

Q: What sampling plan is used?

A: With our typical Low Volume/High Mix programs, we set inspections at 100%.  In High Volume/Low Mix applications, where a sampling plan is preferred or necessary, we apply ASQ/ANSI Z1.4-2008 (R2018): Sampling Procedures and Tables for Inspection by Attributes methods.

Q: My parts were cleaned before you received them. Why would they require cleaning again?

A: The cleanliness of the part can significantly impact both the quality of the coating and the ability of the coating to adhere to the substrate. We must be certain the parts are clean before we coat the parts to guarantee high-quality results.

Q: How do you clean parts before coating?

A: Options include Aqueous automatic PCB washing machines, plasma, IPA, DI water, various saponifiers, and other proprietary materials and techniques. Convection and vacuum ovens are used to ensure a clean and dry substrate. We tailor the cleaning method to suit the part.

Q: What masking techniques are available?

A: Custom masking conventions include liquid latex, non-ammoniated liquid latex, water-soluble liquid latex, RTV Silicones, a large array of tapes, tape dots and any number of caps and boots of various sizes and configurations.  Our skilled technicians have the experience needed to effectively apply and safely remove maskings.

Q: What coating thickness do you recommend?

A: Naturally, the thickness you require is in direct response to your end-use requirements. Urethane (UR) and Acrylic (AR) thicknesses typically tend to be in the .002 - .004" range. Silicone (SR) is slightly thicker. Parylene applications typically run much thinner for similar protection and are controllable from 0.2 microns to over 200 microns.

Q: What is the Advanced Coating inspection protocol?

A: Receiving inspection confirms the identity and count of the shipment and will generally identify gross damage. As the parts move through the process they are inspected after each significant process step by the technicians performing the step. As each process is more detailed, so is the subsequent inspection more detailed. Additionally, independent inspectors evaluate the work after cleaning, masking, and coating steps and they perform the final inspection.  Advanced Coating also offers Source Inspection for customers who require this additional step in their process. 

Q: What is adhesion promotion, and why would it be necessary? What types of adhesion promotion are available at Advanced Coating?

A: Adhesion promotion is a mechanical or chemical process that increases the strength of the bond between Parylene and the target substrate. Not unlike the difference between how paint adheres to the window jam but not the window glass, different substrates offer different levels of adhesion - adhesion promotion levels the playing field. Options include micro-blasting, plasma, and chemical promotion. While micro-blasting may be suitable for some metal or composite parts, it is unsuitable for PCBs and other delicate items. Vapor and/or liquid application of the industry standard A174 organosilane are available as an option in those cases.

Q: What are the typical lead times? Does the lead time vary by coating?

A: Once products are received from the customer, the standard lead time is 5 – 10 business days for all Parylene coating types. Expedited processing is available.


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