Understanding Masking Processes for Parylene Coating

Posted by Jake Hinojoza on Jan 10, 2017 9:00:00 AM
Jake Hinojoza

Conformal coatings like parylene are strong and trustworthy, and they make necessary equipment safe to use and safer to rely on for long periods of time. However, even the best conformal coatings sometimes need a bit of help to perform their duties efficiently--and that's where masking comes in. Masking is a specialized process with a lot of variables, and, while it is necessary for many applications, the specifics aren't always well-known. Today, our conformal coating experts will provide a crash-course in masking.

The Basics of Masking

Masking is a process designed to ensure that the functionality of conformal coatings and the items they're protecting, like printed circuit boards, don't interrupt one another. For example, if parylene were to coat batteries, connectors, grounding points, switches, or other delicate components, the overall functionality of the item itself could be limited, and the rest of the coating might be rendered inefficient. Masking keeps this from happening by protecting identified areas from the coating during the application process. The process is specialized, and there are a lot of variables, but the key is to carefully decide which masking systems are most effective given the item itself and the desired functions.

The Masking Process

The masking process is necessary for making parylene coating as efficient as possible. Let our conformal coating experts explain!

  • Step 1. Identify the areas where parylene coating absolutely cannot be placed. This is crucial since it drives the rest of the process and defines future success.
  • Step 2. Once the proper areas have been identified, it's time to apply specially-created conformal coating masking materials which will ensure that parylene doesn't coat the areas in question.
  • Step 3. Next, the entire device is placed in a vacuum chamber, where the parylene coating is applied. Parylene vapor coats the device, including the masked areas.
  • Step 4. After successful parylene deposition, all of the masked areas are cleaned, leaving the specified areas left untouched and functional.

What You Need to Know

Here's a quick look at what you need to know about the parylene masking process. 

  • Variables. One of the most important parts of the masking process is identifying all of the variables. These include but are not limited to, the type of coating being used, the specific area to be coated, and all involved materials. These variables often have a big impact on the entire process, so knowing what you're dealing with is crucial.
  • Parylene masking. It's important to remember that if you're using one of the most trusted and long-lived conformal coatings--parylene--then you'll need to use a unique masking process. Parylene's application is in a gaseous form, so there is often a need to mask more than just a few specific locations.
  • Issues. As with anything worth doing, there are a few potential issues to look out for when masking. One of these is electrostatic discharge, defined as too much static electricity, which can be controlled by an ionized air blower; another potential problem is improper timing because the relationship between the masking and coating processes is delicate and any timing issues can cause big risks.

Although parylene is an essential component of many devices, this coating sometimes needs a little help to do what it does best: provide reliable, trustworthy protection for a long time to come. That little bit of help comes from the masking process--and it's important to understand just why this process is so beneficial in parylene application.

Why Masking for Parylene Matters

In many applications across many industries, the masking process is crucial because it ensures that the parylene coating doesn't get in its own way. This means that, sometimes, parylene can cause product failures or interfere with performance if the conformal coating gets somewhere it shouldn't be.

For example, at times parylene's benefits can also be its weaknesses--like when its strong dielectric properties cause it to interrupt electric signals on a PCB--and that's where masking comes in.

The masking process works to protect all the benefits parylene offers while limiting the risks. There are a variety of masking conventions, ranging from different types of liquid latex to tapes, tape dots, and various models of caps and boots.

Interested in more information on the masking process? Looking for conformal coating experts and parylene pros? Contact us today!

Topics: Parylene Conformal Coating