## 4 Results of the Measurements and Analyses
### Correlation Analysis
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Names of Parameters for Transistors TR\_A;** & **Total Voids** & **Individual Voids** \\
**BLC10G22 LS-240 PVT** & & \\ \hline T\({}_{\text{emp}1}\) & \(-\)0.096 & 0.086 \\ \hline T\({}_{\text{emp}1}\) & \(-\)0.166 & \(-\)0.056 \\ \hline T\({}_{\text{empmin}}\) & \(-\)0.117 & \(-\)0.016 \\ \hline T\({}_{\text{empaverage}}\) & \(-\)0.033 & 0.116 \\ \hline T\({}_{\text{empDeltaT11T2}}\) & 0.243 & 0.574 \\ \hline R\({}_{\text{thT1}}\) & \(-\)0.111 & 0.144 \\ \hline R\({}_{\text{thmin}}\) & \(-\)0.124 & 0.059 \\ \hline R\({}_{\text{thT2}}\) & \(-\)0.164 & 0.029 \\ \hline R\({}_{\text{thaverage}}\) & \(-\)0.053 & 0.168 \\ \hline T\({}_{\text{a}}\)—ambient temperature & 0.01 & \(-\)0.282 \\ \hline P—power dissipated in the transistor [W] & 0.234 & 0.233 \\ \hline
**Names of Parameters for Transistors TR\_B;** & **Total Voids** & **Individual Voids** \\
**BLC9G22 LS-160 VT** & & \\ \hline T\({}_{\text{emp}1}\) & 0.247 & 0.204 \\ \hline T\({}_{\text{emp}2}\) & 0.112 & 0.103 \\ \hline T\({}_{\text{empmin}}\) & 0.125 & 0.095 \\ \hline T\({}_{\text{empaverage}}\) & 0.19 & 0.178 \\ \hline T\({}_{\text{empDeltaT1 iT2}}\) & 0.547 & 0.423 \\ \hline R\({}_{\text{thT1}}\) & 0.206 & 0.204 \\ \hline R\({}_{\text{thmin}}\) & 0.098 & 0.116 \\ \hline R\({}_{\text{thT2}}\) & 0.088 & 0.122 \\ \hline R\({}_{\text{thaverage}}\) & 0.152 & 0.181 \\ \hline T\({}_{\text{a}}\)—ambient temperature & \(-\)0.194 & \(-\)0.305 \\ \hline P—power dissipated in the transistor [W] & 0.416 & 0.371 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Set of r-value correlation coefficients showing the statistical impact of the individual and total void sizes on selected thermal parameters of the tested transistors. one measured quantity on another, for which the value of R\({}^{2}\approx 50\%\). This value explains with 50% justification how the value of one variable is determined by the variability of the other variable. The Matrix Plot analysis made it possible to check whether the assumption that the resistance value R\({}_{\text{th}}\) depends on the void area is correct. From the obtained results of the values of the correlation coefficient describing the level of the influence of the area of the individual and total voids on the value of the thermal resistances determined in the cross-section of the transistor case, the highest value slightly exceeded 0.2 (Table 2). Such a value of the r coefficient was obtained by verifying the influence of the individual voids' size on the value of the thermal resistance R\({}_{\text{thT1}}\). A similar value of the correlation coefficient was obtained by examining the influence of the size of individual boxes on the average thermal resistance R\({}_{\text{thaverage}}\). For the TR_B transistor, the correlation coefficient was r = 0.18, and for the TR_A transistor, the r value was around 0.17. This level is too low to show whether there is any relationship relevant to the analysis between these values. Therefore, the statistical influence of individual voids on R\({}_{\text{thaverage}}\) changes is negligible. The obtained results of the correlation coefficient, both for the transistors TR_A and TR_B, in none of the cases confirmed the correlation of the size of the voids, both individual and total, with the value of the thermal resistance R\({}_{\text{th}}\), and the results did not even come close to the level of the correlation coefficient r = 0.7. The performed regression analyses and the determined values of the correlations between the selected parameters of the tested transistors presented in Table 2 prove that the total area of the void spaces and the individual area of each of the gaps in the soldering area of the transistor's source have no direct impact on the result of the determined thermal resistance R\({}_{\text{th}}\). Similarly, there is no correlation between the dimensions of the discussed gaps in the soldering area and the temperature value measured on the case at several points of the transistor's cross-section.