Процесс конформного покрытия при производстве сборки печатных плат

Electronic components, big and small, are susceptible to wear and tear after prolonged use. Consumers expect electronic products to last for a long time, so manufacturers have developed methods to protect their components from damage and keep them functional for longer periods of time. One of these methods is called конформное покрытие. This process protects PCBs from mechanical and chemical damage and extends their life and reliability in a variety of ways.

В PCBA fields , more and more boards need to be kept from humidity ,dusty and high reliable insulation. So let go ahead to more information of conformal coating.

What’s conformal coating?

Conformal coating is a special polymer film that protects components and PCB boards from mechanical or chemical damage. It is essential for protecting aerospace components from extreme conditions and was originally developed for mission-critical applications. In the modern digital age, the conformal coating process has become commonplace in many applications, including coatings used by the general public such as mobile devices.

Conformal coating is the process of spraying a dielectric material onto a device component to protect it from moisture, fungus, пыль,коррозия, истирание, and other environmental stresses. Common conformal coatings include silicone, acrylic, urethane, эпоксидная смола, and Parylene.Parylene is a unique polymer conformal coating that conforms to virtually any shape including crevices, points, sharp edges, and flat, exposed internal surfaces. Parylene is a higher level coating process. It used on high quality, надежный,precision requirement products,such as medical equipment.

Распространенные материалы конформных покрытий и их свойства.:

Тип материала	Преимущества	Недостатки	Применимые сценарии
Акрил	Легко наносится/ремонтируется, отсутствие усадки после отверждения, низкая цена	Плохая химическая стойкость, низкая стойкость к истиранию	Общая обстановка, низкие требования к стоимости
Эпоксидная смола	Устойчивость к истиранию и химическому воздействию, хорошая влагостойкость	Трудно удалить, усадка во время отверждения, сложно переделать	Суровая окружающая среда (например, химическое оборудование)
Полиуретан	Хорошая химическая стойкость, можно доработать сваркой	Для чистки требуется стриппер, может оставить остатки	Влажная или агрессивная среда
Силикон	Высокая термостойкость (>120℃), влагостойкость и устойчивость к коррозии	Ограниченная адгезия, сложно отремонтировать	Экстремальная температура или высокая влажность окружающей среды
Уретан	Сильная защита, хорошая адаптация к низким температурам	Плохая производительность при высоких температурах, сложно переделать	Требования к низкой температуре или высокой износостойкости

Three normal way to do conformal coating process

Brush coating works by flow coating the material onto the board and is suitable for low volume application, finishing and repair. The finish tends to be inferior cosmetically and can be subject to many defects such as bubbles. The coating also tends to be thicker and unless skilled operators used the coating, highly subjective in quality. And in this way you can add some fluorescent material to your coating liquid and when you work under a fluorescent lamp you can easily to find out which area or space is not covered the coating.

Spray application coating can be completed with a spray aerosol or dedicated spray booth with spray gun and is suitable for low and medium volume processing. The quality of the surface finish can be superior to all other methods when a trained skilled operator completes?the process, as long as the circuit board is clean and the coating has no adhesion issues. The coating application may be limited due to 3D effects but masking requirements are more shield than barrier since the penetration is less effective. Однако, the lack of penetration can be an issue where coating is desired to penetrate under devices.

Conformal coating dipping

is a highly repeatable process and if the PCB is designed correctly can be the highest volume technique. Coating penetrates everywhere, including under devices, and therefore any masking must be perfect to prevent leakage. Поэтому, many PCBs are completely unsuitable for dipping due to design. The issue of thin tip coverage where the material slumps around sharp edges can be a problem especially in a highly condensing atmosphere. This tip coverage effect can be eliminated by double dipping the PCB, using several thin layers of anatomist spraying to achieve good coverage without exceeding coating thickness recommendations or a combination of the two techniques.

Conformal Coating Curing & Drying

Different Methods of curing / drying are available depending on the conformal coating material.Solvent & Water based conformal Coatings For standard solvent based acrylics, air drying (film forming) is the normal process except where speed is essential. Then accelerated heat curing can be used, используя печи/конвейеры периодического или линейного действия и используя типичные профили отверждения, такие как те, которые предназначены для максимально эффективного отверждения без повреждения покрытия. Конформные покрытия на водной основе можно обрабатывать таким же образом, но с большей осторожностью с применением тепла из-за более медленного времени высыхания..

Leadsintec Co., Ltd, являющаяся одним из производителей OEM, может поставлять более трех обычных поставщиков конформных покрытий на юге Китая.(Шэньчжэнь Сити, Гуандонская провинция). Они предоставили услуги по нанесению конформного покрытия в малых и средних объемах примерно на 6 годы?на фабрике. Вы можете связаться с ними по следующей информации.