Enabling IPX Level 7/8 PCB Waterproof Protection
BY ANDRES HANAU (ENGINEER), ERIC HANSON PHD (VP OF TECHNOLOGY), EDWARD HUGHES (CEO), ACULON, INC.
The miniaturization of electronic products continues to drive Printed Circuit Board (PCB) manufacturing towards smaller and more densely packed boards with increased electronic capabilities. With virtually every electronic device containing at least one PCB, they are a modern marvel and one of the most disruptive innovations of the last one hundred years. However, they have an Achilles heel: water!
Most circuit board enclosures are satisfactory for protecting the delicate components from being damaged by accidental drops or static electricity, but provide limited protection from liquids. According to research from IDC (International Data Corporation), more than 900,000 smartphones are damaged by liquids every day globally¹. IDC’s research revealed that liquid damage is the second-largest cause of damaged smartphones (the primary source of damage being broken screens) with the impact estimated to be worth nearly $100 billion each year. IDC claims that by 2020, more than 1.7 billion smartphones will be shipped at a market value of $398 billion, with the problem of liquid damage only becoming more widespread if not addressed.
The need for waterproofing PCBs goes way beyond smartphones. There has been tremendous interest from producers of tablets, IoT devices, and appliances as well as automated component manufacturers. Because of their delicate nature, electronics manufacturers are challenged to find reliable, economical and high-performance materials that minimizes or mitigates the damage that compromises safety and operation of electronic devices. Increasingly, designers want to build fluid protection into the design to improve product reliability and reduce device failures. As a result of claims by several leading mobile phone brands, consumers are now looking for water resistance and protection as a feature of new improved devices.
Until recently, thick encapsulating coatings or enclosure gasketing have been used to try remedy the situation. Gaskets are very difficult to incorporate on devices with complex shapes (e.g. mobile phones), take up a lot of real estate, and encapsulation eliminates the possibility of reworking a board which creates massive yield losses during manufacturing. Due to these issues, manufacturers turned to conformal coatings, a class of surface treatments that were used for many years to protect circuitry from foreign contaminants like dust, flux residues, etc. Unfortunately, these coatings were not designed to protect devices from direct contact with water. That level of board protection required multiple coats (it can take 10+ successive applications of conformal coating), a process not feasible for high volume manufacturing. Further complicating the process was the introduction of flex connections and press-fit connectors, as well as the use of sensitive devices such as microphones which made masking of these small electronics very time consuming and costly for traditional conformal coating applications.