Parylene Conformal Coating Process

Parylene Coating Process

Parylene Coating Process – Phase 1 – Prior to Parts Arrival

Once we obtain a purchase order from a client, all of the relevant data such as drawings, specifications, and special instructions are given to the quality department from our marketing team to create custom work instructions for that individual assembly.

Parylene Coating Process – Phase 2 – Coating Processes

After the work traveler and other back-end tasks have been finished, the parylene coating production process truly begins in our shipping department.  Once all of the items have been unpacked, they are then routed to incoming inspection.  Here, parts are counted to verify quantity against the customer purchase order and packing slip, as well as inspected to verify that no damage occurred to the assemblies prior to arrival at Diamond-MT.  After incoming inspection, assemblies are then ready for processes unique to that assembly.  For example, if cleaning or cleanliness testing were needed, it would be performed at this time.  Once any unique processes have been finished, the products are then given to our maskers.  Masking is performed per the customer’s drawings and/or written requests for coating keep-out areas.  Once completed, the parts go into masking inspection to verify compliance with the customer’s masking drawing.  After parts pass masking inspection, a proprietary parylene adhesion promotion is administered.  At last, the parylene deposition process is carried out.  Once coating has been deposited, the coated materials have the masking material removed with great care not to damage the thin layer of parylene applied.  The parts are nearing completion, but before they can be packaged up and sent back to the customer, they need to go through a final QA inspection.  The final inspection ensures that all required process stages were successfully completed and that the final product completely meets the terms of the customer’s drawing and specifications.  Final inspections are done on 100% of the customer’s product.  Once the parts pass the final inspection, they are returned to the shipping department to be packed back into the customer supplied boxes and returned.  The parylene coating process is normally a ten business day evolution, but can be completed quicker on a negotiated basis.

Parylene Coating Process – Phase 3 – Post Coating Follow-up

Our sales team is in very close contact with our clients after the coating process to make sure the parylene coating is exactly as the customer requires.  If any changes are necessary to our process, our quality department will diligently with the customer to make sure that the end product is exactly what is expected.

This was a guest post from Sean Horn, Vice President of Diamond-MT.  Diamond-MT is a leading conformal coating service provider located in Johnstown, Pa.

Parylene Conformal Coating Cost

Parylene Cost

Parylene is often quoted out to be the most expensive conformal coating option.  After a review of the factors that affect parylene costs, it should be evident to understand why.  Raw materials, labor, and lot volumes are the most significant pieces of the parylene puzzle that effect pricing.

Raw Materials – Parylene Dimer and Adhesion Promotion

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

Different raw materials are used for different parylene adhesion promotion solutions.  From various board cleaning solutions to A-174 silane, these raw material costs need to be amortized over every piece of product.  Unfortunately, not much can be done about these costs, as adhesion is critical for parylene.

Parylene Labor Costs

Like all conformal coatings, masking is the most labor intensive part of the process.  However, parylene is different from other conformal coatings in that it is applied in a gaseous state through a vapor deposition process.  The parylene molecules will infiltrate anywhere that air can.  As a result, many precautions need to be taken during the masking process to ensure that every connector is completely sealed and all of the masking material used is firmly adhered against the coating keep-out areas.


Another factor that will result in increased labor costs is the increased time spent per board to increase parylene adhesion.  Spending extra time cleaning assemblies and applying different adhesion promotion solutions will increase labor times.

 Parylene Lot Volumes

Items to be parylene coated are placed into a vacuum chamber.  There is a finite amount of space available in the chamber and everything, including the inner dimensions of the chamber, will get coated.  In order to get the lowest cost, we have to maximize the number of products in the chamber.  If we are able to divide the fixed costs among a greater number of boards, the cost per board drastically drops.

This was a guest post from Sean Horn, Vice President of Diamond-MT.  Diamond-MT is a leading conformal coating service provider located in Johnstown, Pa.



Parylene Conformal Coating Thickness

Parylene Thickness

I am interested in parylene, but how thick should I have it applied?  This is a question that is often brought up by customers who are new to conformal coating, especially parylene.
The first thing that we do is explain the parylene coating process and how it differs from conventional conformal coatings.  Typically conformal coatings are applied anywhere from 2 to 8 mils.  Most people are shocked, but pleased to learn that parylene can be successfully and consistently applied to as little as one micron!


Something that is not often taken into account when trying to determine the proper parylene thickness is the amount of clearance needed.  If it is a printed circuit board that is an enclosure, there usually will not be too many clearance issues.  However, in some cases, even an extra mil of coating can cause extra mechanical abrasion to the parylene which can result in damaged parylene.


Another factor to consider is the dielectric strength required.  For applications that require a higher dielectric strength, a thicker coat of parylene has better dielectric properties than a thinner coat.  Trying to balance the dielectric strength concern with clearance concerns is a tight rope to walk and often requires some testing to determine the proper balance.


In the simplest of cases, an end item customer, who is familiar with parylene, has specified the coating thickness to be applied and made this requirement a part of their drawing or specification.  After our review the drawing and comparison of the drawing to the assembly, we will be able to determine if any potential issues with the parylene thickness are present and make suggestions accordingly.


This was a guest post from Sean Horn, Vice President of Diamond-MT.  Diamond-MT is a leading conformal coating service provider located in Johnstown, Pa.