Determination of the glass transition temperature of electrotechnical prepregs by differential scanning calorimetry (DSC)

Electrotechnical prepregs are used as gluing gasket in the manufacture of multilayer printed circuit boards. These materials are obtained by fiberglass impregnation with a mixture of modified epoxy resins. The glass transition temperature (T_g) of the cured prepreg is determined by differential scanning calorimetry. This universal approach provides a wide range of instrumental parameters and does not contain numerical values of metrological characteristics. We present a methodology of T_g determination taking into account the requirements of GOST and experimental conditions and assess the metrological characteristics of the technique. Cured samples of prepregs produced in Russia and aboard were studied. Thermograms were recorded for two samples of each prepreg. T_g was calculated from the transition on the curve of second heating at a rate of 20 °C/min. It has been shown that the relative total error of the method is ±4%. Since in some cases the visible glass transition was not recorded on the thermograms of cured prepregs, a linear approximation of the T_g dependence from a high heating rate at which the glass transition is more pronounced to the value of 20 °C/min was carried out. Control of the correctness of the determination was carried on samples for which T_g can be confidently determined by extrapolation and traditional experimental-calculation methods. It is shown that both extrapolation and calculation methods lead to the same results within the limits of the analytical error. The obtained results can be used for determining T_g of electrotechnical prepregs and incoming inspection of the corresponding product.

1. Xie C., Zou H., Wei-Yao., Wang M. Research on reliability of non-flow prepreg filling in automotive R-F PCB / 16th International microsystems, packaging, assembly and circuits technology conference (IMPACT). — Taipei, Taiwan, 2021. P. 82 – 85. DOI: 10.1109/IMPACT53160.2021.9697053

2. Liu T., Devarajan M. Influence of prepreg material properties on printed circuit board stack-up / 72nd electronic components and technology conference (ECTC). IEEE. — San Diego, CA, USA, 2022. P. 2244 – 2248. DOI: 10.1109/ECTC51906.2022.00354

3. Borozdina E. A. Methods of testing the adhesive gasket used for manufacture of multilayer printed circuit boards. http:// www.dnevnikinauki.ru/images/publications/2023/11/technics/Borozdina.pdf (accessed 17.05.2024) [in Russian].

4. Shimkin A. A., Safronov A. M. Quality control of polymer binders by DSC / Industr. Lab. Mater. Diagn. 2016. Vol. 82. N 8. P. 30 – 33 [in Russian].

5. Shimkin A. A., Grebneva T. A., Merkulova Yu. I. Determination of degree of cure of thermosetting resins using IR-spectroscopy and differential scanning calorimetry / Industr. Lab. Mater. Diagn. 2017. Vol. 83. N 8. P. 27 – 32 [in Russian].

6. Makarova N. Yu., Evstafev S. S. Analysis of domestic materials for the production of printed circuit boards / Research and practice conf. «Intelligent systems and microsystems engineering»: coll. of works. — Moscow: MIET, 2022. P. 283 – 291 [in Russian].

7. Dubrovsky A. V., Egorov A. V. Concideration of expansion of domestic base materials implementation in bare boards production / Electronics: Science, Technology, Business. 2022. N 3(214). P. 160 – 165 [in Russian]. DOI: 10.22184/1992-4178.2022.214.3.160.164

8. Murzin V. S., Nechiporenko E. V., Kotova S. V., et al. Styrene-butadiene thermoplastics as the basis of adhesive compositions / Kauchuk Rez. 2021. Vol. 80. N 1. P. 16 – 19 [in Russian]. DOI: 10.47664/0022-9466-2021-80-1-16-19

9. Jiang J., Lu Z., Shen J., et al. Decoupling between calorimetric and dynamical glass transitions in high-entropy metallic glasses / Nature Commun. 2021. Vol. 12. P. 3843 – 3851. DOI: 10.1038/s41467-021-24093-w

10. Khamidullin O. L., Madiyarova G. M., Rezvykh A. V., et al. Comparative analysis of thermal expansion and thermal capacity of polymers based on a series of epoxy novolak resins in a wide range of temperatures / Vestn. Tekhnol. Univ. 2021. Vol. 24. N 5. P. 40 – 44 [in Russian].

11. Van Miltenburg J. C., Cuevas-Diarte M. A. The influence of sample mass, heating rate and heat transfer coefficient on the form of DSC curves / Thermochim. Acta. 1989. Vol. 156. P. 291 – 297. DOI: 10.1016/0040-6031(89)87197-7

12. Gaisford S. Fast-scan differential scanning calorimetry / Eur. Pharm. Rev. 2008. Vol. 4. P. 83 – 89.

13. Gabbott P. V. Fast Scanning DSC / Principles and Applications of Thermal Analysis. — Wiley Blackwell, 2007. DOI: 10.1002/9780470697702.ch2

14. Ford J. L., Mann T. E. Fast-Scan DSC and its role in pharmaceutical physical form characterization and selection / Advanced Drug Delivery Reviews. 2012. Vol. 64. P. 422 – 430. DOI: 10.1016/j.addr.2011.12.001

15. The handbook of differential scanning calorimetry. Techniques, instrumentation, inorganic and pharmaceutical substances. — Oxford: Elsevier, 2023. — 853 p. DOI: 10.1016/C2015-0-05607-6

16. McGregor C., Bines E. The use of high-speed differential scanning calorimetry (Hyper-DSC) in the study of pharmaceutical polymorphs / International Journal of Pharmaceutics. 2008. Vol. 350. P. 48 – 52. DOI: 10.1016/j.ijpharm.2007.08.015

17. Poel G. V., Mathot V. B. F. High performance differential scanning calorimetry (HPer DSC): a powerful analytical tool for the study of the metastability of polymers / Thermochim. Acta. 2007. Vol. 461. P. 107 – 121. DOI: 10.1016/j.tca.2007.04.009

18. Liu P., Yu L., Liu H., et al. Glass transition temperature of starch studied by a high-speed DSC / Carbohydrate Polymers. 2009. Vol. 77. P. 250 – 253. DOI: 10.1016/carbopol.2008.12.027