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The Importance of Masking Parylene

Posted by Scott Curtis on January 26, 2017

In its first 42 years, all professional hockey goalies played goal without a mask, exposing their faces to all forms of peril. That all changed in 1959, when Montreal Canadiens goalie, Jacques Plante, was struck in the face by a flying puck that opened up a cut from the corner of his mouth all the way up through his nostril. After being stitched up, Plante returned to the Canadiens bench, but refused to re-enter the game unless he could wear his facemask to protect the injury. Coach Toe Blake, reluctantly agreed and only tolerated the mask as long as Plante triumphed. Plante won that game 3-1 and continued to rattle off an incredible 18-game winning streak. As a result, the goalie mask caught on and the NHL was changed forever.

A goalie mask or a hockey mask is designed for the purpose of protecting a goaltender’s face and skull from pucks and sticks as they defend their crease. Today, it’s hard to imagine a player taking the ice without a mask for protection. Likewise, it is inconceivable for a conformal coating house to coat a product with Parylene without masking its sensitive components.

Mask_Circuit_Board

Parylene protection and masking
The purpose of Parylene is to provide environmental and mechanical protection to extend product life, prevent costly repairs and, most importantly, reduce the risk of failure. Parylene has beneficial qualities for products such as, printed circuit boards (PCBs), LEDs and medical devices that require dependable functionality. However, if Parylene coating gets in the wrong place it can interfere with the integrity and performance of the product causing it to fail. Therefore, one of the most critical stages in the Parylene coating process is properly masking the product.

Prevent failures with proper masking
Some of Parylene’s key properties can be a problem depending on where the conformal coating is applied. Parylene coatings are dielectric, meaning that the coating material is an insulator and thus a poor conductor of electrical current. For instance, sensitive components like a connector on a PCB will not function properly in some cases once Parylene conformal coating has been applied. Therefore, to gain the benefits from Parylene coating, keep-out areas need to be masked to prevent failures from inadvertent coating.

The Parylene masking process
At Para-Coat Technologies, our highly-trained staff understands the importance of conformal coating masking materials and the effective process in protecting components from ingress of Parylene coating. Improper or poor Parylene masking can compromise the coating or possibly cause failure of the finished product. Therefore, proper masking for Parylene coating is one of the most important phases. Although the masking process can be labor-intensive and time-consuming, it is important to clearly identify the keep-out areas not to be coated during the deposition of Parylene.

After the masking phase, the product is thoroughly inspected to ensure that all areas have been properly masked and then it is placed into the vacuum chamber for Parylene deposition. Parylene is vapor-deposited and uniformly coats all surfaces of the substrate. However, on the areas that are masked, the Parylene is deposited on the masking materials instead of on the actual substrate. Thus, preventing any sensitive regions from being coated. Typical masking materials are masking tape, masking tape dots, masking boots, and liquid latex.

Conclusion
In the sport of ice hockey, goalie is one of the most important and toughest positions to play.  But wearing a mask enhances a goaltender’s competing performance and helps prevent serious head injuries. Similarly, masking for Parylene conformal coating is a challenging and complicated process with many variables.  But when performed properly, Parylene coating offers a degree of protection and performance that few other types of conformal coatings can match.

Contact PCT for more information about Parylene or visit Parylene Coating Technology.

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Para-Coat Technologies
17 Johns Street
Johnstown, PA 15901
Phone: (814) 254-4376
Fax: (814) 254-4057