Molecular‑Level Penetration + Nano‑Scale Film‑Forming: How Nano‑Coatings Achieve Full Coverage of 0.1 μm Gaps?

Traditional conformal coatings generally have a surface tension above 30‑40 mN/m and relatively high viscosity. When applied, they can only cover the macroscopic surfaces of components and fail to penetrate tiny gaps. For BGA packaged devices, the bottom pin pitch can be as small as 0.4 mm with gap heights of only tens of micrometres. For micro‑components such as 0201 devices, the gaps between pins and pads even drop to the sub‑micrometre level. Conventional conformal coatings can hardly provide effective coverage in these areas, leaving numerous unprotected dead zones. Moisture and salt mist penetrate through these zones, resulting in solder joint corrosion, short‑circuit and other failures.

Huayi‑series nano‑coatings feature an ultra‑low surface tension of 15‑20 mN/m. According to the Washburn capillary penetration equation, a liquid’s penetration capacity into narrow gaps is positively correlated with surface tension and negatively correlated with viscosity. The ultra‑low surface tension of nano‑coatings provides excellent capillary driving force, enabling spontaneous penetration into gaps merely 0.1 μm wide.

Meanwhile, fluorine‑containing active molecules within the coating chemically react with functional groups such as hydroxyl groups on substrate surfaces to form covalent bonds. The dual mechanism of molecular‑level penetration plus chemical bonding ensures comprehensive protection on both macroscopic surfaces and inside micro‑gaps.

Conventional conformal coatings usually achieve less than 60 % coverage for regions such as BGA bottoms. By contrast, nano‑coatings realise over 95 % gap coverage via capillary penetration. In compliance with coating quality requirements specified in IPC‑A‑610 standard, nano‑coatings further improve protection integrity on the basis of meeting standard requirements, offering a feasible technical route for high‑density electronic product protection.

After high‑density PCBs from Huayi Brothers were treated with TUW‑series (TUW‑2708) nano‑coating, fluorescence inspection confirmed that the coating sufficiently penetrated traditional blind areas including BGA bottoms and pin gaps of 0201 components. After 500‑hour 85 °C / 85 %RH double‑85 testing, the PCBs maintained normal electrical performance, verifying the protection reliability brought by molecular‑level penetration.