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58 DESIGN007 MAGAZINE I OCTOBER 2025 in these types of harsh environments, such as tire pressure monitoring systems (TPMS) and remote water monitoring sensors, are especially vulner- able. In such cases, mechanical enclosures alone provide insufficient protection. In addition to common sensor vulnerabilities, crit- ical automotive systems must meet stringent reli- ability and safety requirements. In automotive sys- tems, fail-safe mechanisms are designed to bring the vehicle to a safe state or prevent hazardous conditions in the event of a component failure. Potting resin enhances these systems by encap- sulating sensitive electronic components, includ- ing advanced sensors, controllers, and power sup- plies, within a solid protective material. This resin shields them from environmental factors such as moisture, dust, and chemicals, mechanical stresses such as shock and vibration, and fire. By doing so, it enhances durability and ensures that fail-safe oper- ations are maintained under harsh operating condi- tions, supporting overall system reliability. Even when devices are enclosed, environmen- tal challenges persist, particularly due to temperature fluctuations. Temperature changes can cause conden- sation to form inside sealed enclosures. This occurs in both metal and plastic housings, but the damage is often more severe in plastic because water vapor can slowly permeate many polymer materials. The risk is even greater in submerged or oceanic applica- tions, where high external pressure drives the ingress of corrosive salt water. Protecting sensitive electron- ics in these conditions demands solutions that block both liquid and vapor-phase moisture. Potting protects sensitive electronics by encapsu- lating them in high-performance materials that block moisture and contaminants while providing mechan- ical support to withstand vibration and shock. Choose Your Champion Selecting the right potting compound is key to per- formance and long-term reliability, requiring careful consideration of the material's properties and the demands of the application. Potting material chem- istry determines its properties and the level of pro- tection they provide. The most common options are epoxies, silicones, and polyurethanes, with each offering distinct advantages and trade-offs. • Epoxy-based potting compounds: Epoxy- based potting materials provide excellent adhesion, strong chemical resistance, and exceptional moisture protection. However, once cured, epoxies become rigid, which can introduce mechanical stress on delicate components when there is a significant mis- match in coefficients of thermal expansion (CTEs). As temperatures fluctuate, the epoxy expands and contracts at a different rate than the PCB or its components, leading to board warping and cracked solder joints or leads, ultimately resulting in device failure. • Silicone-based potting compounds: Silicone- based potting materials, ranging from gels to rubber-like elastomers, provide excellent tem- perature resistance up to 200°C, and outstand- ing flexibility. Their inherent softness allows them to absorb the thermal expansions and contractions caused by CTE mismatch, thereby reducing mechanical stress during temperature cycling. However, silicones offer only moderate resistance to moisture and chemicals. They are permeable to water vapor and can swell when exposed to oils, limiting their effectiveness in Pot t i n g c o m p o u n d e n c a p s u l at i n g m oto r w i n d i n g s . ▼ A n a u to m ot i ve e l e ct ro n i c c o nt ro l u n i t . ▼