How to Estimate Parylene Coating Costs
Posted by Sean Horn
Friday, July 29, 2016 7:30
@ 7:30 AM
Often considered the ultimate conformal coating, Parylene is well suited to protect many types of products and devices.
At the same time, Parylene is generally the most expensive of the five major coating types, which means estimating the potential cost of your Parylene coating project is essential.
The Factors That Go Into Estimating Parylene Coating Costs
There are two primary factors that go into the cost of Parylene. Thorough understanding of them will help you estimate how much your project will cost. These factors are:
- Raw material costs
- Labor costs
Parylene Raw Material Costs
Most Parylene “runs” require about a pound of raw Parylene dimer.
A single pound of dimer can cost anywhere from $200 to $5,000 per pound, with cost differences dictated by the type and quality of the Parylene.
3 Questions to Help You Estimate Cost
When it comes to the costs of Parylene raw materials, there are three questions you should ask:
1. “What Variety of Parylene Am I Going to Use?”
The C and N varieties of Parylene are the most common types. They have costs much closer to the $200 per pound.
Specialty Parylene varieties such as D or AF4 have higher costs, but also provide higher performance (better heat resistance, better UV protection, etc.)
It’s essential that you work with a company that has deep experience with Parylene. They’ll be able to help you choose the right variety of Parylene for your needs.
2. “What Is the Size and Quantity of the Objects I Need to Have Coated?”
This is important because the objects you’re having coated will be placed into a vacuum chamber during the process.
The coating chamber has a fixed cost to do one coating run. Maximizing the number of objects we place in the coating chamber on each run will lower your cost. In some cases, simply optimizing the number of items you have in each run can dramatically lower the total cost per item.
3. How Much Masking Am I Going to Use?
If there is a lot of labor involved in the masking, it goes without saying that costs will be higher. If possible, speak with an expert prior to designing your device. Sometimes design changes can be made that will result in a device that’s significantly easier to mask and coat—resulting in cost savings for you.
Parylene Labor Costs
As with any coating process, masking is usually the most labor-intensive part of the Parylene process. However, Parylene is different from other coatings in that it is applied in a gaseous state through a vapor-deposition process. Parylene molecules will penetrate anywhere that air can. As a result, great care needs to be taken during the masking process to ensure that every connector is adequately sealed and all tape is firmly pressed against the coating keep-out areas.
Another factor that will result in increased labor costs is the increased time spent per item to increase Parylene adhesion. Spending extra time cleaning products and applying different adhesion promotion mediums will result in increased labor times.
The Cost of Parylene Defects and Rework
Coatings made of acrylic, for example, are relatively easy to remove using chemical solvents.
Unfortunately, once Parylene has been applied to an object, it is extremely difficult to remove. Because of this, costs can quickly escalate if any defects happen during the coating process.
Engineers usually turn to one of three methods when trying to remove Parylene coating: thermal, mechanical, and microabrasion. Each method is labor intensive and relatively expensive compared to a Parylene run with minimal defects.
1. Thermal Removal
Parylene is heat-resistant, but local application of extreme heat can melt or burn through a the coating. This method is often a poor or risky choice for many applications; the associated extreme heat and prolonged exposure will damage many underlying devices. In the case of printed circuit boards, the plastic board will melt before the Parylene coating does, making thermal removal practically impossible.
2. Mechanical Removal
Mechanical methods include scraping, sanding, picking, and cutting.
Practically, however, Parylene is colorless and extremely thin, making it difficult for a technician to know when he or she has actually removed the coating. Because of this, mechanical removal options have a high risk of damaging the underlying device, because technicians simply can’t tell when to stop sanding or scraping.
3. Microabrasion Removal
Microabrasion is often the best option to remove Parylene. Technically, microabrasion is a specialized type of mechanical removal. It uses a stylus with a tiny nozzle to direct a stream of pressurized air and abrasive materials at the device. A vacuum pulls away the abrasive material and the removed coating.
This method is much easier to control than mechanical sanding or scraping, which is why it usually leads to better results.
The Best Way to Accurately Estimate Parylene Coating Costs
Ideally, the best way to accurately estimate Parylene coating costs is to avoid mistakes in the first place.
Since raw material and labor costs can be fairly easy to estimate, depending on the requirements of your project, the only variable that can’t be planned for are defects.
The importance of properly preparing your device for Parylene coating success cannot be stressed enough.
Here are the three things you should know to help ensure Parylene coating success:
- The specific variety of Parylene that’s right for your project.
- The number of devices or objects you can coat in a single run of Parylene.
- The amount of masking that will be required for your project.
As always, the most effective way to prevent coating failures is to ensure you’re working with an experienced Parylene coating provider, like Diamond-MT.
To learn more about how to keep parylene costs low, download our whitepaper: