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.