Analysis of a CMOS Chip Circuit Board using the stand-alone FTIR Microscope LUMOS II

Significance of the Topic

Modern electronic devices feature miniaturized components that are highly susceptible to microscale contaminants. Identifying chemical composition at the micrometer level is crucial to prevent device malfunctions and guide effective troubleshooting. FTIR microscopy provides a powerful approach to detect both organic and inorganic impurities on complex samples.

Study Objectives and Overview

The application note AN M106 demonstrates the use of the stand-alone LUMOS II FTIR microscope to analyze contaminations on a CMOS image sensor and a circuit board contact. The aim is to locate, characterize, and identify micro-contaminants that can degrade device performance.

Methodology and Used Instrumentation

The study employed a fully integrated FTIR microscope offering ATR, transmission, and reflection measurement modes with motorized ATR crystal and stage mapping. The workflow is guided by dedicated software for automated background and sample acquisition.

• Instrument: Bruker LUMOS II stand-alone FTIR microscope
• Measurement modes: ATR, transmission, reflection
• Software: OPUS Video-wizard with built-in spectral library

Main Results and Discussion

Analyses revealed a uniform protective polymer layer identified as poly(methyl methacrylate) covering the CMOS sensor. Localized green contaminations on the Bayer matrix matched polyamide or protein spectra, suggesting biological or synthetic polyamide origins. On the circuit board, FTIR mapping detected:

• Polyamide contamination on a gold contact
• Lipid film residues on apparently clean gold surfaces
• Epoxy resin from the base board material
• Silicone-based solder resist in coated regions

These findings demonstrate the technique’s sensitivity to both visible and invisible contaminants across diverse materials.

Benefits and Practical Applications

FTIR microscopy with LUMOS II enables rapid, high-resolution chemical imaging without extensive sample preparation. Its compact design and user-friendly automation suit applications in:

• Quality control and failure analysis in microelectronics
• Contamination assessment in pharmaceutical and biomedical fields
• Forensic investigations of trace residues
• Materials research for polymers and composites

Future Trends and Potential Applications

Advancements may include integration with complementary imaging methods (e.g., Raman microscopy), AI-driven spectral interpretation, and inline process monitoring systems for real-time contaminant detection in manufacturing environments.

Conclusion

The LUMOS II stand-alone FTIR microscope offers a versatile, automated solution for microscale chemical analysis. Its high spatial resolution, combined with seamless library searches, facilitates efficient identification of diverse contaminants, making it an invaluable tool for analytical laboratories in electronics and beyond.

References

• Bruker Optics. Application Note AN M106: Analysis of a CMOS Chip Circuit Board using the stand-alone FTIR Microscope LUMOS II. 2021.