Meaning
Non-contact optical measurement techniques evaluate surface flatness and dynamic deformation across a range of temperatures. The shadow moiré method utilizes a reference grating placed above the sample to create interference patterns that reveal topographical changes. This technique provides high-resolution, full-field displacement data for analyzing warpage in printed circuit boards and electronic packages.
It is widely used to evaluate packaging materials and design configurations before starting mass production.
Optical Mechanism
Interference fringes are generated when the shadow of a linear grating projected onto a surface is observed through the grating itself. In the shadow moiré setup, the distance between these fringes corresponds to a specific height change on the sample. By capturing these patterns with a digital camera, software calculates the precise out-of-plane warpage across the entire surface.
This automated analysis provides a complete three-dimensional map of the substrate surface without physically touching the sample.
Reflow Simulation
Environmental chambers integrated with the optical system allow engineers to measure how components bend when heated. By combining the shadow moiré technique with a heating element, the system simulates the entire temperature profile of a reflow oven. This testing reveals whether a chip will bend excessively at peak temperatures, which would lead to open circuits or short circuits.
It helps assembly plants identify problematic component geometries before they reach the assembly line.
Industrial Compliance
High-density packaging factories in China use this testing technology to qualify new suppliers of printed circuit boards. Sourcing agreements require the shadow moiré data to accompany the pre-production sample batches to prove compliance with dimensional tolerances. This qualification step is required to minimize assembly line downtime and ensure reliable solder joints for advanced chip packages.
Independent test reports generated by these optical systems are treated as legally binding proof of material compliance in disputes over component defects. Audit teams regularly inspect the calibration of these optical systems at subcontracted factories to guarantee the consistency of the warpage data across different production sites.
