Cross Section Evaluation
Metallographic inspection procedure uses visible light magnification to evaluate internal physical structures of printed circuit boards and solder joints. Microsection laboratories perform om testing on microsection coupons to measure plating thickness and internal layer registration. Calibrated optical equipment reveals subsurface physical defects such as micro-voids and plating cracks that remain hidden from surface visual inspection.
Quality assurance departments compare optical images against IPC standards to verify structural conformance after thermal stress testing. Quantitative measurements extracted from calibrated microscopic images validate manufacturing process stability across production batches. The inspection procedure stops applying when internal feature resolution requirements fall below visible light wavelengths and require scanning electron microscopy.
Failure Analysis
Microscopic structural evaluation identifies mechanical fracture sites and void distribution within non-conforming solder connections. Reflected light illumination highlights grain structure boundaries and intermetallic layer growth along metallic interfaces. Laboratory technicians document microstructural anomalies to isolate root causes of field failures or qualification test rejections.
Sample Preparation
Precision sectioning and polishing steps expose target micro-features without introducing artificial mechanical damage. Abrasive grinding media systematically smooth coupon surfaces until optical clarity allows clear distinction between distinct metal layers. Etching solutions accentuate grain boundaries to improve visual contrast during optical analysis.
Careful specimen preparation prevents edge rounding that distorts thin plating layer thickness measurements.
