Parylene’s (XY) reputation as the most versatile and reliable of major conformal coating materials is well-earned. However, unlike liquid coatings –resins of acrylic, epoxy, silicone and urethane – parylene cannot be applied via relatively economical brush, dip or spray methods. XY can be the most expensive of the major conformal coatings to use, a factor influenced both by:
- material costs and
- its chemical vapor deposition (CVD) application procedure,
- which generally requires smaller-batch rather than large-scale processing.
These conditions assure there is no set-cost for parylene coating; expenditures will vary according to assignment specifics. They also speak to the importance of obtaining a reliable estimate of production costs before engaging a coating contractor. Learning about parylene, its various types, procedural requirements and labor costs is an effective way of assuring you aren’t overcharged for your conformal coating projects.
Item to be Coated
Assignment requirements – materials/processes used as well as price – are largely determined by the item to be coated, whether this be an entire printed circuit board (PCB), specific components, medical device, military/automotive hardware. These project-specific conditions affect cost. Materials-to-be covered – plastic, ceramic, metal, etc. – are also a factor, as is size; length, width, maximum thickness influence batch size – the number of items fitting in the deposition chamber. Larger items require more coating and mean smaller batches, increasing process-time, adding to project expense. Maximizing the number of objects in the coating chamber on each run lowers costs. Providing the vendor detailed drawings/plans is suggested.
End-product Application/Operating Environment
The objective of thin film application is to assure optimal performance for end-product use. Operating environment also determines coating requirements. This means cost will be a factor of such conditions as the device’s:
- suggested coating thickness (IPC standard = 10-50 micron),
- cleaning/cleanliness testing required prior to coating,
- minimum/maximum working temperatures,
- masking requirements specified with diagrams,
- whether testing is needed after parylene coating/specific test details if any,
- batch volumes/timeline if the device is currently in production, or
- projected volumes/timeline if not.
A reputable firm like Diamond can help you determine these requirements if any questions exist, a consideration of importance since all influence production expense and the quoted project cost.
Type of Parylene Required
When considering possible conformal coating vendors, it is a good idea to look at the types of parylene offered. Prominent parylene types include varieties C, N, F, D, and AF-4, each with a distinctive range of chemical, electrical and physical properties, and subsequent uses. Price differences depend on the type and quality of XY required to best complete the coating assignment. Depending on the XY-type, a single pound of parylene dimer can range from $250.00 to $5,000.00.
Working with a parylene provider with deep experience in the industry and a good reputation – Diamond comes to mind in this regard – will help assure the appropriate type of XY material is used for your coating assignment. Since:
- the most common XY types – varieties C and N – cost in the range of $250/pound, and
- specialty XY -- F or AF4, for instance – have significantly higher costs,
- you’ll want proven professional reliability making material selections.
This is not only a matter of price; you do get what you pay for, although types C and N have an extreme range of applications where they fulfill all required thin film functions, other varieties provide better performance for specialty applications. They are suggested for assignments requiring higher thermal resistance, enhanced UV protection, etc., according to the project’s coating needs.
When determining the necessary coating materials, please keep in mind these factors:
- In addition to lower cost, types C and N adhere more readily to most substrates than other parylene types, whose deposition rates are slower and costlier. Types C/N offer strong resistance to chemical corrosion, with less trace metal contamination, and are used for most current parylene applications.
- Type F offers enhanced MEMS/nanotech utility, due to a degree of thermal stability supporting ultra large-scale integration -- one million+ circuit elements positioned on a single chip, as well as inner layer dielectric applications. F has a lower dielectric constant and lesser coating capacitation/operational electrical charge.
- More expensive Parylene D provides effective coating protection at 134° C (273° F), and reliable component protection for 10 years at 100° C, in oxygen-dominated environs.
- AF-4 is also costlier, but is more suitable for specialized applications, with better UV-stability and higher oxidative resistance,
Because XY is the most expensive coating material, receiving an accurate price quote is essential. Supply your selected parylene provider with reliable figures concerning device size and quantity of objects you want coated, as well as accurate drawings/explanations of other project specifications. From there, your provider can determine the parylene variety most appropriate to project completion on time and on budget.
Diamond MT’s 17 years’ experience is augmented by a staff of well-trained personnel, quality materials and process solutions to generate optimal implementation of your conformal coating assignment. We guarantee competitively-priced, consistent quality service, with thoroughly documented production/inspection procedures. We focus on providing exceptional and economical parylene coating, with rapid project turnaround.
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