## 3 Results and Discussion
### Printing Orthogonal Experimental Designs  
In the paste printing experiment, the print line width was adjusted by changing three parameters: substrate moving speed, print height, and feed pressure. The three parameters could take effect separately and influence each other. The feed pressure directly determined the flow rate of the nozzle outlet, the substrate moving speed primarily affected the degree of stretching of the paste, and the print height was closely related to the stability of the \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Shear Rate** & \(K\) & \(n\) & \(\tau_{y}\) (Pa) \\ \hline \(15\ s^{-1}\) & 49.46 & 0.6184 & 24.48 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Rheological parameters of the conductive paste. Figure 3: Flow chart of research steps. printing process. Figure 4 schematically illustrates the photo and schematic diagram of the printing process. The orthogonal test method was used to carry out the paste printing experiment. The above-mentioned feed pressure P, print height H, and substrate moving speed v, which had a great influence on the line width, were selected as the influencing factors of the experiment. Each factor had three levels, and the specific values of the levels of each experimental influencing factor are shown in Table 3.  
In the orthogonal test, the average line width of the paste printed on the substrate was taken as the investigation index. According to the specific requirements of the experiment, the \(L_{9}\left(3^{4}\right)\) orthogonal table was used for the test. The final designed orthogonal test scheme and the nine groups of printing experimental results carried out according to this scheme were recorded, and they are listed in Table 4. Except for the three parameters, the rest of the experimental parameters used the default values. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Test Number** & **P** & **H** & **v** & **Blank Column** & **Line Width c/\(\mu\)m** \\ \hline
1 & 1 & 1 & 1 & 1 & 80.82 \\
2 & 1 & 2 & 2 & 2 & 53.93 \\
3 & 1 & 3 & 3 & 3 & 48.59 \\
4 & 2 & 1 & 2 & 3 & 70.30 \\
5 & 2 & 2 & 3 & 1 & 59.83 \\
6 & 2 & 3 & 1 & 2 & 67.24 \\
7 & 3 & 1 & 3 & 2 & 65.33 \\
8 & 3 & 2 & 1 & 3 & 100.74 \\
9 & 3 & 3 & 2 & 1 & 74.87 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Three-factor and three-level orthogonal experimental design and experimental results. Figure 4: (a) Industrial camera real image of the printing process. (b) Schematic diagram of the paste printing model. \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Level**} & \multicolumn{3}{c}{**Factor**} \\ \cline{2-4}  & **Feed Pressure P/MPa** & **Print Height H/\(\mu\)m** & **Substrate Moving Speed v/(mm/s)** \\ \hline
1 & 0.6 & 100 & 50 \\
2 & 0.7 & 150 & 100 \\
3 & 0.8 & 200 & 150 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Factor level table. In order to determine the degree of influence of the influencing factors on the investigation index, the corresponding range analysis was carried out for the experimental results in Table 4, and the range analysis results of each parameter on the printing line width are summarized in Table 5, where \(K_{i}\) represents the sum of the corresponding index values at the i\({}_{\text{th}}\) level of this column of factors, \(k_{i}\) represents the average value of the index results corresponding to the i\({}_{\text{th}}\) level of this column of factors, and \(R\) represents the range value corresponding to each column of factors. The size of the range \(R\) determined the primary and secondary influence of each factor on the experimental index. The larger the value, the greater the influence of the factor on the index. According to the data analysis in Table 5, the range \(R\) values corresponding to the feed pressure, print height, and substrate moving speed were 19.20 \(\upmu\)m, 8.58 \(\upmu\)m, and 25.02 \(\upmu\)m, respectively.