Destructive Micro-Sectioning Protocols for Detecting Hyper Corrosion Spikes in ENIG
Destructive micro-sectioning with nitric acid etching isolates ENIG hyper-corrosion spikes under SEM to reject defective PCB lots before assembly.
Metallography
Meaning
Microstructural analysis of metals and alloys provides the foundational data needed to evaluate the physical properties and failure modes of engineering materials. Through the practice of metallography, quality engineers examine grain size, phase distribution, and internal defects within structural components or electronic assemblies. This discipline is governed by standard methodologies such as GB/T 13298, which outlines the requirements for preparing and analyzing metal specimens.
The application of this analysis is focused strictly on the internal material structure, excluding macroscopic mechanical strength tests.
Structural Revelation
Specimen preparation is the most critical stage, demanding careful grinding and polishing to avoid altering the metal grains. An acid etch is then applied to the polished surface, which preferentially attacks the grain boundaries to make them visible under a light microscope. Researchers use the resulting images to assess the heat treatment history and potential weaknesses of the material.
Regulatory Compliance
Government laboratories and certified third-party testing agencies in China perform these examinations to verify that structural metals used in construction and transport meet national safety codes. The results are compiled into official verification reports that manufacturers must submit to obtain market entry approvals. These documents carry legal weight and can be used as evidence in product liability disputes.
Analytical Constraint
The examination remains a destructive technique that requires cutting a sample out of the finished product. This prevents its use as a continuous online inspection tool, limiting its role to periodic batch validation and failure analysis.