Issue link: https://iconnect007.uberflip.com/i/1540984
NOVEMBER 2025 I SMT007 MAGAZINE 71 • Surface Insulation Resistance (SIR) SIR is a critical metric for evaluating the elec- trical performance of conformal coatings, particularly in high-reliability sectors such as automotive, aerospace, and defense. SIR testing exposes conformally coated PCBs to extreme conditions, including temperature cycling, humidity, and condensation, often while a large bias voltage is applied. The test then measures the board's resistance to sur- face leakage currents. A high SIR value indicates that the coating is effectively blocking moisture and contaminants, thereby reducing the risk of ECM, dendritic growth, and short circuits. In mission-critical applications, consistently high SIR values are essential to meet stringent standards and demonstrate the coating's ability to prevent latent failures that could compro- mise safety or functionality. Industry standards such as IPC-TM-650 and IEC 60664 typically mandate sustained SIR values of 108 Ω, even after prolonged high-stress aging, such as exposure to 85°C and 85% relative humidity under bias voltage for several hundred hours. • Sustainability and Greener Materials The electronics industry is under increasing global pressure to reduce its reliance on sol- vent-based PCB assembly materials that emit VOCs. At the same time, environmental regu- lations such as RoHS and REACH are driving suppliers away from toxic "forever chemicals" like PFAS and toward safer, more sustainable alternatives, such as bio-based ingredients derived from renewable plant sources rather than crude oil. UVFlex: Redefining Conformal Coating Performance Electrolube UVFlex is a breakthrough UV-curable, high-elasticity conformal coating based on ure- thane acrylate chemistry. It delivers an optimized balance of flexibility and toughness, combining excellent moisture and chemical resistance with the speed and efficiency of UV curing. Together, these properties are establishing a new benchmark for conformal coating performance. Key Properties of UVFlex • Flexibility and toughness: Maintains a low modulus of elasticity (E) after thermal aging, demonstrating flexibility even at -40°C • Thermal performance: Tg of -42°C, with a continuous operating temperature range of -40°C to +135°C • Moisture and chemical resistance: Excellent barrier properties, even under severe envi- ronmental stress • Efficient dual-cure system: Rapid UV cure supports fast processing, while secondary moisture cure ensures thorough crosslinking and complete cure even in shadowed areas • Inspection and process control: Built-in fluo- rescent UV tracers simplify inspection and enhance process control • Precision application: Thixotropic formula- tion supports applications with automated selective-spray equipment, ensuring uniform coverage even on sharp edges ▼ E xa m p l e s of c o m p o n e nt c ove ra g e w i t h U V F l ex c o nfo r m a l c o at i n g .