Py-GC HR-TOF of Circuit Board Polymer

Significance of the Topic

Reliable identification of polymer composition and additives in complex electronic materials is critical for quality control, regulatory compliance and failure analysis. Traditional GC/MS with solvent injections often fails to detect high-mass or halogenated fragments generated by pyrolysis. High-resolution TOF mass spectrometry coupled with pyrolysis (Py-GC HR-TOF) overcomes these limitations by providing accurate mass measurements that enable molecular formula determination for unknown pyrolysis products.

Objectives and Study Overview

This application note illustrates the use of Py-GC HR-TOF to analyze a printed circuit board polymer. The goals are to:

• Determine the base polymer type.
• Identify halogenated flame retardants embedded in the polymer matrix.
• Demonstrate how high resolution accurate mass data improves compound identification compared to nominal mass TOF.

Methodology and Instrumentation

Sample Preparation and Pyrolysis:

• 100 µg of circuit board material pyrolyzed in a CDS Model 5200 Pyroprobe.
• Pyrolysis temperature: 750 °C, hold time 30 s.
• Transfer line, valve oven and interface maintained at 325 °C.

Gas Chromatography and Mass Spectrometry:

• GC system: Pegasus® GC-HRT (High Resolution Time-of-Flight MS).
• Carrier gas: helium, split ratio 50:1, injector at 325 °C.
• Column: 5 % phenyl, 30 m × 0.25 mm.
• Mass range: 35–550 amu; detector operated in high-resolution mode for accurate mass measurement.
• Oven program: 40 °C (2 min) → ramp 10 °C/min to 300 °C → hold 5 min.

Main Results and Discussion

Nominal mass TOF analysis showed characteristic pyrolysis fragments of bisphenol A and isopropyl phenol, indicating a polycarbonate backbone. Additional peaks corresponding to bromomethane, bromophenols and tetrabromobisphenol A (TBBPA) suggested presence of halogenated compounds not typical of polycarbonate.

High-resolution measurements enabled assignment of molecular formulae to previously unidentified peaks. These were confirmed as mono-, di- and tri-bromobisphenol A homologues. The accurate mass data conclusively demonstrated that TBBPA is integrated into the polymer during manufacturing (“in-polymer” flame retardant) rather than surface-blended.

Benefits and Practical Applications

Using Py-GC HR-TOF for circuit board analysis offers:

• Definitive polymer identification by characteristic pyrolysis products.
• Detection and structural assignment of halogenated additives absent from conventional MS libraries.
• Improved confidence in compliance testing for RoHS and other regulations.
• Enhanced failure analysis by revealing in-polymer versus surface additives.

Future Trends and Potential Applications

Advancements in high-resolution MS and pyrolysis sampling are expected to drive:

• Expanded accurate-mass libraries for polymer additives and degradation products.
• Integration with chemometric tools for automated material classification.
• Broader use in environmental monitoring to track polymer leachates.
• Multi-technique coupling (e.g., pyrolysis-FTIR/MS) for complementary structural information.

Conclusion

Py-GC HR-TOF provides a robust platform for comprehensive analysis of complex polymeric materials. Accurate mass measurements reveal detailed composition, including embedded flame retardants, that cannot be confidently identified by nominal mass systems. This approach enhances material characterization in research, quality control and regulatory contexts.

Applied Instrumentation

• Pyrolysis unit: CDS Model 5200 Pyroprobe.
• GC-HR-TOF: LECO Pegasus® GC-HRT.