Glass transition temperature comparison
Figure 5 shows the glass transition temperature of FR4 plates measured with different thermal analysis techniques. It can be seen from the figure that the glass transition temperature measured by the DSC technique is slightly higher than the glass transition temperature measured by the TMA technology. This is due to different heating rates and systematic errors in different technologies.
TGA measurement
The thermal weight loss technique (TGA) is mainly used to measure the mass change of the FR4 plate in the heating process and can well characterize the thermal decomposition process of the organic matter in the FR4 plate. Samples of different compositions, under different atmospheres, the volatile products formed by thermal decomposition and residues are different. In the actual measurement process, the initial decomposition temperature in the air atmosphere can be a good comparison of the thermal stability of different FR4 boards. The DTG curve is derived from the differential derivative of the TG curve, which is proportional to the rate of decomposition weight loss of the sample. The synchronized SDTA curve reflects the endothermic and exothermic effects of the entire heating process, which is useful for analyzing the entire weight loss process. The endothermic effect at 300°C in Fig. 6 is closely related to the flame retardant effect of the FR4 board; at 450 to 550°C, the FR4 decomposition product is burned in air and the residue is glass fiber.
Figure 7 shows the TG curves of FR4 panels at different heating rates. Different heating rates, the initial decomposition temperature is different. Therefore, there is no real decomposition temperature. The kinetics of decomposition weight loss has important practical value for investigating and predicting the thermal stability of materials at different temperatures. The STARe software from METTLER TOLEDO can provide two kinds of dynamics software: n-level dynamics and non-modelling dynamics, where n-level dynamics software is suitable for ideal reaction conditions; non-modeling kinetics (METTLER TOLEDO's unique dynamics software) and The actual reaction has a good agreement, and has a very good practical application prospects (Figure 8).
Figure 5 Comparison of DSC and TMA tests for glass transition temperature