Electromagnetic shielding coatings serve as core protective materials for 5G communications, precision electronics and new energy equipment. Featuring ultra-thin profiles, superior shielding efficiency and wide compatibility, they effectively block electromagnetic interference and prevent signal leakage, enabling stable operation of electronics under complex electromagnetic environments. They are now the mainstream lightweight electromagnetic shielding solution.

Silicon carbide (SiC) ceramics feature outstanding thermal conductivity, high-temperature resistance, wear and corrosion resistance, widely adopted in semiconductor manufacturing, new-energy PV, aerospace thermal protection and high-temperature metallurgy. Their service performance is dominated by grain morphology, grain boundary conditions and residual stress.

The Han Dynasty marked a pivotal era of rapid advancement and widespread popularization of ancient Chinese iron smelting technology. Private iron smelting flourished in the early Western Han Dynasty. Emperor Wu of the Han implemented state monopolies on salt and iron, establishing a nationwide iron official system that enabled large-scale and standardized iron production. During the Eastern Han Dynasty, Du Shi invented the hydraulic blast furnace bellows, which harnessed water power for air blowing and drastically raised smelting temperatures and production efficiency. Meanwhile, sophisticated techniques such as puddling steel and malleabilizing cast iron reached maturity, producing tough, high-performance iron and steel. Iron tools and utensils were widely adopted across handicrafts and daily life, driving the progress of manual industries. Overall, innovations in Han ironware laid a solid material foundation for the unified imperial dynasty, boosted comprehensive socioeconomic growth, and shaped the technical framework of China’s traditional iron civilization.

Silicon-based chips are the core carrier of semiconductors, widely adopted in consumer electronics, new energy industrial controls, automotive chips, AI intelligent devices and more. Chip pads serve as critical structures for component packaging and pin interconnection, undertaking core functions including circuit conduction and signal transmission. The structural integrity of pads directly governs packaging yield and long-term device reliability.

As a key wearable part for automatic sock knitting machines, this cutter ring trims excess yarn and separates finished socks automatically. It is made of SK5 spring steel, undergoing stamping, rolling, tooth milling and heat treatment. The cutting edge is locally coated with nickel-based diamond composite layer via electroplating, including pre-nickel plating, diamond grain co-deposition and final polishing.

Ultra-small gold-plated stainless steel tubes (4mm × 0.55mm) combine the high strength, wear resistance and excellent air tightness of stainless steel with the low impedance, oxidation resistance and good solderability of gold plating. Widely used in precision electronics, optical communication, medical devices and RF connectors, these micro components serve for precision signal transmission and micro-sealing conduction, delivering long-term anti-corrosion performance for high-end miniaturized equipment.

ENEPIG (Electroless Nickel-Palladium-Gold) stands as a dominant surface finish for high-performance PCBs. Built with compact, uniform Ni-Pd-Au triple-layer coating, it features superb oxidation & corrosion resistance plus low contact resistance.It eliminates black pad issues from conventional immersion gold while supporting both soldering and wire bonding for complex electronic assembly.

Purpose：Metallographic cross-sectioning is performed to examine voids, intermetallic compound (IMC) layers, and other potential defects in PCB solder joints. The specimen is prepared by sectioning using the Table Cut 200 automatic flatbed cutting machine, cold mounting with TJ2226 cold mounting resin, and grinding and polishing using the Alpha 610 automatic grinding and polishing machine. The detailed sample preparation procedure is described in the following preparation method.