Nowadays, electronic products are deeply integrated into our lives, but water is their greatest enemy. Many people have experienced their phones falling into water, such as dropping them into puddles on rainy days, getting them wet in the bathroom, or having them submerged by waves at the beach. This often leads to short circuits in the phone's motherboard, resulting in high repair costs or the need for a replacement. Action cameras with poor waterproofing may experience blurry and flickering images during diving, and internal water ingress can corrode and render electronic components unusable. Smartwatches with inadequate waterproofing designs can suffer from water penetration during handwashing or swimming, leading to unresponsive touchscreens, battery malfunctions, and safety hazards. Electronic products are prone to short circuits when exposed to water, damaging components and reducing performance and lifespan, making waterproofing essential.
Encapsulation provides excellent waterproofing, isolating components to prevent short circuits and offering strong chemical stability, resisting corrosion from various substances. It is widely used in electronic products requiring high stability, such as automotive ECUs, ensuring stable operation in harsh environments. However, encapsulation waterproofing also has limitations. The high hardness after curing leads to poor heat dissipation, and repairing faulty components is difficult, requiring the destruction of the encapsulation layer, which may damage other parts.
Structural Waterproofing
Structural waterproofing is the basic line of defense for electronic product waterproofing. It primarily uses clever structural design and sealing materials to prevent water ingress. It's like giving electronic products a sturdy "armor," physically isolating them from water sources. Common structural waterproofing methods include waterproof rings, waterproof gaskets, and waterproof grooves.
Waterproof rings, usually made of elastic materials such as silicone or nitrile rubber, create a tight seal at the junction of two components. For example, a waterproof ring is often installed between the screen and body of a mobile phone. When the phone is splashed with water or briefly submerged, the waterproof ring deforms under pressure, filling the gaps and preventing water from entering the phone, protecting the delicate internal electronic components. This method is low-cost, easy to install, and effectively handles general waterproofing scenarios in daily life, such as accidental splashes while washing hands. However, the waterproofing effect of waterproof rings gradually decreases with time and usage, as long-term compression and friction cause the ring to age and lose elasticity.
Waterproof gaskets are similar to waterproof rings, also using the elasticity of the material to achieve sealing. However, waterproof gaskets are more flexible in shape and size, adapting to various irregular surfaces. Waterproof gaskets are used in some cameras' battery compartments and memory card slots. They fit tightly against the edges of the compartment cover and the camera body, preventing moisture from seeping in during opening and closing. Besides waterproofing, these gaskets also provide some cushioning, reducing friction and impact between components. However, they have durability issues, and if improperly installed, they can shift, compromising the waterproofing effect.
Waterproof grooves, on the other hand, create a waterproof barrier by designing grooves on the casing and using sealing materials. When moisture comes into contact with the casing, it is guided into the waterproof grooves instead of directly entering the interior. This design is common in some high-end laptops, where carefully designed waterproof grooves are found at the connection between the screen and the body. Waterproof grooves offer reliable waterproofing performance and can withstand significant amounts of water, but they require higher manufacturing precision, increasing production costs and design complexity.
Potting and Encapsulation for Waterproofing
Potting and encapsulation involve filling the internal voids of electronic products with liquid potting material, which then solidifies to form a robust whole, providing multiple protections such as waterproofing, moisture resistance, and salt spray resistance. Epoxy resin potting compound is a commonly used potting material.
Epoxy resin potting compound has excellent insulation properties, effectively isolating electronic components and preventing short circuits. It also possesses good chemical stability, resisting corrosion from various chemical substances and protecting electronic components from damage. Potting and encapsulation technology is widely used in electronic products requiring extremely high stability, such as automotive electronic control units (ECUs). During driving, cars face various complex environments, such as rain, mud splashes, and high temperature and humidity. The potting compound ensures that the electronic components inside the ECU can still operate stably in such harsh environments.
However, potting and encapsulation also have limitations. On the one hand, the high hardness of the potting compound after curing leads to poor heat dissipation, which is a significant problem for electronic devices that generate a lot of heat. On the other hand, if an electronic component fails, the repair difficulty is greatly increased due to the encapsulation. Repair often requires damaging the encapsulation layer, which is not only time-consuming and laborious but may also damage other components.
Surface Coating for Waterproofing
Surface coating for waterproofing involves applying a special protective coating to the surface of the circuit board or casing of electronic products to achieve waterproofing. Common surface coating waterproofing methods include conformal coating and PCB nano-coating.
Conformal coating, mainly composed of acrylic resin, polyurethane, and silicone, forms a protective film on the circuit board surface, providing moisture resistance, dirt resistance, mold resistance, waterproofing, and salt spray resistance. It is often applied to the circuit boards of some ordinary electronic devices, such as home routers. It can effectively prevent dust and moisture from corroding the circuit board, extending the service life of the device. However, the thickness of conformal coating is generally tens of micrometers, which is relatively thick and affects the heat dissipation performance of the circuit board. Moreover, its protective ability is limited and may not provide sufficient protection against prolonged immersion or high-pressure water spraying. PCB nano-coating is a new type of protective coating with a thickness of only nanometers, making it almost invisible to the naked eye. Compared to conformal coatings, nano-coating offers better heat dissipation performance because its extreme thinness hardly impedes heat transfer. At the same time, nano-coating also boasts superior waterproofing capabilities, meeting the waterproof requirements of daily life, such as the water resistance of mobile phones. Some smartwatches utilize nano-coating technology on their circuit boards, effectively preventing water damage even when worn while washing hands or swimming. Furthermore, nano-coating exhibits excellent corrosion resistance, passing a 500-hour salt spray test, whereas typical conformal coatings struggle to withstand a 48-hour salt spray test. However, the cost of nano-coating is relatively high, which may limit its large-scale application.
Other Waterproofing Methods
In addition to the common waterproofing methods mentioned above, there are other waterproofing technologies also used in electronic products.
Ultrasonic welding utilizes high-frequency ultrasonic vibrations to generate frictional heat at the welding surface of plastic components, thereby achieving welding. This welding method can achieve a high degree of sealing at the seams of the casing, effectively preventing moisture intrusion. The casings of some waterproof speakers use ultrasonic welding technology to ensure that the speakers can function normally in humid environments or underwater.
Waterproof double-sided tape is also a commonly used waterproofing material. It has good adhesion and waterproofing properties and can be used to connect components such as the panels and casings of electronic products. In some tablet computers, waterproof double-sided tape is used to bond the screen to the frame, ensuring both secure screen installation and waterproofing.
Two-shot molding involves a second injection molding process after the first injection molding, combining components of different materials or functions. This method can create waterproof structures in critical parts of electronic products. For example, in some smart bracelets, two-shot molding is used at the button area to create a tight waterproof connection between the button and the casing, preventing moisture from entering through the button gaps.
Waterproofing design for electronic products is a systematic engineering process that spans the entire process from material selection and structural planning to testing and optimization. By comprehensively utilizing various technical means such as structural waterproofing, potting, and surface coating, and meticulously handling details such as buttons and interfaces, coupled with rigorous waterproof performance testing, the waterproof capability of electronic products can be significantly enhanced. Waterproof design is of great significance to the performance and user experience of electronic products. It protects products from water damage, extends their lifespan, reduces repair and replacement costs, and meets users' needs in diverse scenarios, allowing them to enjoy the benefits of technology more freely. In market competition, electronic products with excellent waterproof performance are more attractive, helping to enhance brand image and competitiveness. Therefore, designers, manufacturers, and consumers of electronic products should all attach importance to waterproof design. Designers should continuously innovate and optimize waterproofing solutions; manufacturers should strictly control the process to ensure that waterproof performance meets standards; and consumers should consider waterproof performance as an important factor when making purchasing decisions. It is hoped that all parties will work together to push the waterproof performance of electronic products to new heights, adding more convenience and peace of mind to life.
