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Materials Science



Enabling IPX level 7/8 waterproof protection

By Andres Hanau, Eric Hanson and Edward Hughes of Aculon - 30/10/2018

Andres Hanau, Eric Hanson and Edward Hughes of Aculon describe R&D in the chemistry of conformal coatings, leading to the development of an encapsulant technology capable of forming a hydro/oleophobic coating for consumer electronics.
 
According to research firm IDC, nearly 900,000 smartphones are damaged by liquids every day, with an estimated impact of $96.7 billion a year. The demand for smart phone waterproofing is driving an industry standard which will likely create competition based on levels of protection. This challenges manufacturers to find economical and high-performance materials for IPX7 and IPX8 ratings:
  • IPX7: full water immersion for 30 minutes while powered ‘on’ at one-metre depth
  • IPX8: immersion in over one metre of water.
Manufacturers turned to conformal coatings, normally used to protect circuitry from contaminants like dust, but while conformal solution-based and vacuum-deposited coatings protect circuitry from contamination and humidity, neither is capable of waterproofing electronics produced in mass manufacturing environments. It would take 10 or more successive applications to get protection from liquid – a process not feasible for high-volume manufacturing.
 
Introducing a ‘true’ conformal coating
As a result of extensive R&D, Aculon has developed a no mask hydro/oleophobic encapsulant technology capable of forming a ‘true’ conformal coating. It maintains a consistent thickness across complex components, which provides a high degree of water resistance. While previous chemistries required masking of connector hubs so other parts could be electrically connected after coating, this new surface treatment is applied directly to connectors, which prevents the points from becoming a point of failure upon water immersion.
 
NanoProof is a new class of coating chemistry that achieves IPX7 and IPX8 protection, while providing a water and oil repellent surface to circuitry, even within the tight constraints imposed by high-volume manufacturing lines. It can be readily applied by high speed jetting or dispense equipment to sensitive component areas, eliminating the need to mask or dam to fill with the treatment. This coating chemistry also contains no volatile organic compounds (VOCs), so it is highly desirable in regions where tight atmospheric controls are in place.

Using the fundamentals of molecular self-assembly, these novel coatings are economical and can be applied in-line via straightforward processes at the manufacturer. They eliminate the need for costly capital investments, and mitigate the bottlenecking batch process of vacuum-based manufacturing or masking operations.
 
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Tested against conventional coatings
NanoProof coatings were tested against two traditional conformal coatings: acrylic-based Humiseal 1B315, and polyurethane-based Conathane CE-1164. IPX7 and IPX8 qualification of devices coated with Aculon NanoProof 7.0 and 8.4 were evaluated. The devices were also tested for moisture and insulation resistance.
 
General IPX7 immersion testing standards call for the immersion of finished devices in regular water for 30 minutes. Aculon’s IPX8 modified testing was more strenuous in that an exposed board was directly submerged and polarized in salt water with 18 volts of direct current over 60 minutes.
  • Compared to an uncoated IPC board, the leakage current seen with NanoProof 7.0 was scaled down by a factor of nearly one hundred thousand.
  • With NanoProof 8.4, there was
  • Superficially, indicators show that two-dimensional test circuitry of the four tested coatings (HumiSeal, Conathane, NanoProof 7.0 and NanoProof 8.4) demonstrated similar circuit protection from water.
  • However, when functional 3-D circuitry devices were tested with HumiSeal and Conathane coatings, they exhibited corrosion and device failure in under 60 minutes of saltwater immersion, while devices coated with NanoProof 7.0 and 8.4 did not (Figure 1).
  • NanoProof 7.0 and 8.4 also exceeded the criteria for moisture and insulation resistance.
Conclusion
Aculon’s NanoProof coating chemistries create an insulation barrier for electronics, protecting them from liquid media and prevent liquid-induced damage during operation. In today’s competitive marketplace, where the value of electronic devices, a lack of water resistance is becoming a serious problem for device designers and manufacturers. Application of the latest generation of hydro/oleophobic coatings may provide longevity to devices under ‘real-use’ circumstances when exposed to liquids.

Click on the video below to see the NanoProof coating in action.
 
Authors:
Andres Hanau (Engineer), Eric Hanson PhD (VP of Technology), Edward Hughes (CEO) at Aculon Inc, 11839 Sorrento Valley Rd #901, San Diego, CA 92121, USA
T: +1 585 350 9499
E: info@aculon.com