When applying coatings in electronics manufacturing, precision is everything—especially when it involves connectors, earth pads, and components like switches that must remain uncoated. Traditionally, this meticulous task required manual masking, a time-consuming process that demanded intense focus and care.
Circuitwise is thrilled to announce a significant leap forward in our manufacturing capabilities with the recent installation of an automated coating line and media application in several different applications.
The technology can be used for everything from building 3D structures, dam and fill protection, sealing enclosures, glob top spot protection, flip chip underfill, encapsulation and application of heat transfer media.
Conformal coating
The primary application is conformal coating. This cutting-edge technology revolutionizes our coating process, utilizing advanced nozzles and a fiducial camera to apply a flawless, uniform layer of coating precisely where it’s needed—eliminating the need for manual masking.
But we didn’t stop at just coating. The new coating system is positioned in a production line packed with advanced equipment, both upstream and downstream, as shown below:
A magazine loader is used to efficiently load large numbers of PCB boards onto the conformal coating production line. With selectable pitch settings, stepper motorised pushing and more, this machine helps make your manufacturing process as efficient as possible.
Circuitwise selected the Protecto XP V4 Automated Conformal Coating System from Rehm Group. It’s packed with advanced features such as a heatable nozzle that guarantees a constant lacquer temperature, automatic needle measurement checks and automatic self-cleaning during downtime. It’s optimised for maintaining high quality, even for low volume production.
A UV inspection machine examines the PCBs under ultraviolet light, fluorescing the coatings allowing cameras to capture and inspect high fidelity images for any irregularities. This ensures adequate coating thickness with no gaps and surface coverage in all the targeted areas.
The new line also includes an inline infrared oven for speeding up the curing process under environmental control to ensure an optimal bond with the PCB and that no quality issues arise from dust or moisture.
A magazine unloader completes the line, ensuring efficient unloading of large numbers of PCB boards. An arriving PCB is taken up by the attached conveyor and then pushed into the magazine by a specially designed pusher. The magazine indexes to the next position and is ready for the following unloading cycle.
What we can learn from Apollo 13 about conformal coating
Installation of the conformal coating reminds us of an early blog we published about a fascinating scene in the iconic movie Apollo 13. In the scene, the astronauts are repowering the electronics of their capsule after a few days of freezing temperatures when all the electronics have developed a nice coat of frost. There is a tense moment as the control panels warm up with water dripping off them before the spacecraft successfully comes back to life. Without knowing the details of Apollo 13’s electronics, it is safe to say they probably had some form of conformal coating, allowing them to operate in such wet conditions.
Fast forward to 2022 as the Internet of Things technology mega-trend continues, we are seeing electronics being deployed in an exponentially increasing variety of locations, often exposing them to harsh environments, including a burgeoning space industry. Conformal coating is the go-to option for improving the performance of PCBAs and prolonging their life span in such conditions.
There are many reasons to use conformal coatings including:
Preventing arcing and allowing tighter designs
Inhibiting corrosion
Resistance to fluids and high humidity
Protection from temperature extremes
Abrasion resistance
Soften and protect sharp edges
Overall conformal coatings increase reliability against extremes in environmental conditions and lengthens the life of the product. In addition, as the coatings form a very thin film, typically around 50 µm thick, “conforming” easily to the irregular contours of the substrate, there is minimal effect on the weight of the component.
There are several types of resin to choose from including acrylic, silicone, epoxy, urethane and parylene. Acrylic is the most popular as it's easy to apply, does not shrink and is most affordable. It is easily removed with solvents to facilitate rework but that makes them unsuitable for environments where they may encounter unwanted solvents. For chemically harsh environments, polyurethane coatings provide better protection. Epoxy coatings are ridged and generally used in physically harsher applications. Silicone has better insulating properties so better for exposure to high temperatures above 150°C.
The astronauts of Apollo 13 probably owed their lives to someone who paid attention to conformal coating and today we need to take the same attitude to any product in harsh environments.
Circuitwise is proud to invest in state-of-the-art technology to provide our customers, especially those developing devices for aerospace, medical and space applications, with the best possible service.
This equipment was purchased with the support of a Supply Chain Resilience grant from the Australian government.
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