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

Analysis of a CMOS Chip Circuit Board using FTIR Microscopy

Significance of the Topic

Modern electronic systems are built on increasingly miniaturized components whose function can be compromised by microscopic contamination. Identifying these deposits at the chemical level is essential for troubleshooting malfunctions and ensuring product reliability in microelectronics, quality control and forensic investigations.

Study Objectives and Overview

This application note demonstrates how the stand-alone LUMOS II FTIR microscope can be applied to:

• Locate and chemically characterize contaminations on a CMOS image sensor.
• Analyze material composition on a circuit board’s gold contacts and surrounding structures.

Methodology and Instrumentation

The LUMOS II integrates an FTIR spectrometer with a fully motorized microscope and dedicated user interface. Measurement modes include ATR, transmission and reflection. A motorized ATR crystal automates background and sample runs. A high-resolution video camera and a motorized stage enable precise positioning and mapping down to a few micrometers. Spectral identification relies on built-in library searches using OPUS software.

Main Results and Discussion

On the CMOS sensor, ATR measurements revealed a transparent poly(methyl methacrylate):butadiene layer covering the Bayer filter array. Localized green-coloured residues matched a polyamide/protein signature, indicating biological or synthetic nylon contamination. Clean metal contacts showed no IR absorptions. On the circuit board, FTIR spectra identified:

• Polyamide contamination on gold contacts.
• A lipid film on seemingly clean gold surfaces.
• Epoxy resin in the black ring around the contact.
• Silicone-based solder resist on other board areas.

Benefits and Practical Applications

The LUMOS II permits rapid, high-resolution chemical mapping of complex electronic components without external spectrometers. Fully automated ATR measurements and library-based identification streamline workflows and reduce operator expertise requirements. This approach is invaluable for failure analysis, forensic diagnostics and quality assurance in microelectronics and related industries.

Future Trends and Possibilities

Advances may include integration of AI-driven spectral interpretation, higher spatial resolution optics and multimodal imaging combining FTIR with Raman or SEM. Portable miniaturized systems could enable in-field diagnostics. Expanded spectral libraries and chemometric tools will further enhance detection of trace contaminants.

Conclusion

The LUMOS II FTIR microscope offers a compact, automated solution for detailed chemical analysis of microscale structures on electronic devices. Its ability to identify both organic and inorganic residues facilitates targeted troubleshooting and quality control, addressing challenges in microelectronics and beyond.