Protect Your PCB’s: How to Waterproof Devices for a Low-Cost

by | Mar 16, 2020

The first rule of developing a waterproof product is simple: don’t reinvent the wheel. Tons of devices already exist with simple waterproofing techniques that can be used repeatedly. After all, it is likely that your new device is innovative due to its function, not because of the way it will protect itself from moisture. MistyWest broke down multiple devices to reveal 4 ways that you can easily, and cheaply, waterproof a product and protect those precious, internal electronics:-

Reduction in the number of seals used

Sealing is the process of joining mechanical surfaces together using certain tools (seals) to produce an enclosure. For protecting the PCBs(Printed Circuit Board), proper sealing on the enclosure surrounding the PCB is very important as the quality of work here impacts the entire circuit body inside. Poor sealing causes moistening or dissembling of the enclosure. For most product designs, O Rings (Static and Dynamic) seals and Face gaskets are most commonly used.

For high-quality waterproofing of circuit boards, it is better to have lesser sealing points on the surface. Although sealing ensures blocking of water passage, be sure to check that it is the only possible entry point for fluids unless the surface body corrodes. Therefore, PCB enclosure designers must follow the most appropriate sealing mechanism that can withstand the required physical tests.


Using gaskets to improve waterproof designs:

Gasket, an elastomeric component, fills the space between two intersecting surfaces. This effectively prevents any fluid to pass through the gaps and cause leakage in the entire circuit. Gaskets work because they are made of elastic material and can be customized as per any design specification. There are no standard design restrictions with Gaskets. Since PCBs have multiple small-sized components that are not perfectly connected, Gaskets can be used to fill the spaces in the end.

For safeguarding PCBs, the most common types of gaskets include Sheet Gaskets, Spiral Wound Gaskets, Double Jacketed Gaskets and Fishbone Gaskets. Circuit boards are a mesh of closely joined components and sensors. Therefore, moisture in one part of the board can instantly spread to the entire surface. With Gaskets, the possibility for leakage is either eliminated or restricted to the affected portion only.

O-Rings - A great and cost-effective tool:

For all waterproofing requirements wherein the connection is absolutely or mostly circular or sometimes even non-circular, O-Rings can be used. O-Rings are available in a diverse range of shapes and sizes that mostly cover the sealing requirements. Since total custom development is not required, using O-Rings saves time and effort, making them highly cost-efficient. These rings are useful for separating a fluid contained in one part from the rest of the circuit board. They are usually compressed between the two joining surfaces to produce a sealing effect. O-rings follow a standardized size chart and are denoted by a Dash Number, to describe their size. The larger the last two digits of the ring ID, the larger is the O-Ring. Thus, it is easy to pick them as per the requirement.

O-Rings are mostly categorized into Dynamic and Static types. Compared to a Static ring, which is also the standard ring, Dynamic rings require less compression and can adjust dynamically.

Pressure, the major factor:

Though using gaskets and O-Rings are an effective way of sealing, the quality of the seal depends on the pressure applied to the sealings. An appropriate amount of pressure must be applied to the seal, anything more or less would cause damages to the seal and therefore to the device. This process of applying pressure can be done by using clips, threads and fasteners.

Fasteners are small tools used to strengthen the impact of the sealing. The most common example of a fastening technique is the use of screws, nuts and bolts. Besides applying more pressure, they help by keeping the PCB enclosure intact in case the impacts of the sealing deteriorates. They are available in various standard sizes.

These 4 simple but equally effective techniques are likely all you need to develop a completely waterproof enclosure while also saving you money. Taking inspiration from the devices you use in your everyday life for waterproofing, allows you to fully focus your attention on the true patentable function of your product.
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