Conformal coatings like parylene are relied on everywhere, from aerospace to the doctor's office--so it's important that these coatings are trustworthy. One problem that can arise is called "cracking," and it can be a big issue if not taken care of properly. Let our conformal coating experts explain.
Conformal Cracking Issues and Causes
Conformal coating usually covers a substrate surface in a smooth, uniform layer. When cracking occurs, that layer fractures, creating an uneven surface that looks somewhat like a snake shedding its skin. This can be a big problem since every crack is an opportunity for contaminants and moisture to get to the coated surface.
Cracking is often due to temperature problems during the curing or drying process, or, in the case of parylene, when the wrong type or thickness of the coating is used for the wrong job.
Since cracking can lead to system failure or interruption, it's important to apply all preventative measures necessary--and, if cracking does occur, then it's crucial to take care of it quickly.
3 Important Facts About Parylene Cracking
Why is parylene cracking different than cracking in other coatings? What are the most important details? Our conformal coating experts are here to explain.
Application. By nature, parylene is applied differently than other coatings. It is not applied in a liquid form--but varying temperatures during the application process can still cause cracking, so it's important to take extra care. One key aspect of parylene application is the vapor deposition process, which involves depositing a gas onto the substrate to form a thin, continuous film. This unique application method allows for precise control over the coating thickness and ensures uniform coverage. However, it also means that temperature fluctuations during the deposition process can lead to cracking. To prevent this, it is crucial to carefully monitor and control the temperature throughout the entire application process.
Thickness. Since parylene's thickness can be so closely monitored, it never hurts to make the coating a little thinner to avoid the possibility of cracking. Parylene remains flexible and reliable at all thicknesses. The thickness of the parylene coating plays a crucial role in its performance and resistance to cracking. While thicker coatings may provide enhanced protection, they are more prone to cracking due to their rigidity. On the other hand, thinner coatings are more flexible and less likely to crack. By carefully determining the appropriate thickness for the specific application, it is possible to strike the right balance between protection and flexibility, minimizing the risk of cracking.
Temperature. Temperature has a lot to do with the success of any conformal coating. It's not just varying temperatures, either; if the wrong temperature is used at the wrong time, or a period of extreme heat is followed by extreme cold, then cracking becomes more likely. Temperature control is crucial during every stage of the parylene coating process. From the pre-treatment of the substrate to the deposition and curing steps, maintaining the correct temperature is essential to ensure the integrity of the coating. Sudden temperature changes or exposure to extreme temperatures can cause thermal stress, leading to cracking. Therefore, it is important to adhere to the recommended temperature ranges and ensure a gradual transition between temperature fluctuations to minimize the risk of cracking.
By understanding these three important facts about parylene cracking, you can take the necessary precautions to prevent it and ensure the long-term reliability of your conformal coatings. Proper application techniques, careful consideration of coating thickness, and meticulous temperature control will go a long way in maintaining the integrity of your parylene coatings and protecting your sensitive electronic components from contaminants and moisture. With the help of our conformal coating experts, you can confidently rely on parylene coatings to provide exceptional protection and performance in various industries, from aerospace to medical applications.
