# Development of a Novel Deployable Solar Panel and Mechanism for 6U CubeSat of STEP Cube Lab-II
## 3 A PCB-Based High-Damping Deployable Solar Panel Module  
### Design Description  
Figure 3a,b show the demonstration model of a highly damped deployable solar panel module's stowed and deployed configurations, respectively. The solar panel module is comprised of a PCB panel with thin stiffeners attached by adhesive tapes, a three-pogo pin-based HRM, and torsional hinges. The PCB panel of dimensions 325.4 mm \(\times\) 193 mm \(\times\) 1.6 mm is made up of FR4 material and provides a mechanical interface for mounting solar cells and stiffeners. Five layers of thin 0.4 mm FR4 PCB stiffeners, as shown in Figure 3, \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Time (min)** & **Parameter** & **Power (W)** & **Power (Wh)** & **Charge/ Discharge (Wh)** & **Remarks** \\ \hline \multirow{2}{*}{Daylight} & \multirow{2}{*}{72} & Generation & 33.29 & 39.95 & \\ \cline{3-5}  & & Consumption & \(-\)18.38 & \(-\)22.06 & \\ \hline \multicolumn{5}{c}{Average power for charging} & \multicolumn{2}{c}{17.89} \\ \hline \multicolumn{5}{c}{Actual power for charging (Considering conversion eff.)} & \multicolumn{2}{c}{11.44} \\ \hline Eclipse & 27 & Consumption & \(-\)18.38 & \(-\)9.19 & \(-\)9.19 & \\ \hline \multicolumn{5}{c}{Power margin} & \multicolumn{2}{c}{2.25} \\ \hline \multicolumn{5}{c}{Power budget (\%)} & \multicolumn{2}{c}{5.63} \\ \hline \multicolumn{5}{c}{Battery depth of discharge (DoD) (\%)} & \multicolumn{2}{c}{13.41} \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Energy balance analysis in mission operation mode of Earth observation. \begin{table}
\begin{tabular}{c c} \hline \hline
**Items** & **Mass (g)** \\ \hline Printed circuit board (PCB) panel & 201.5 \\ \hline Thin stiffeners & 85 \\ \hline Viscoelastic tapes & 3 \\ \hline Pogo pin-based HRM & 6 \\ \hline Hinges and fasteners & 11 \\ \hline Total & 306.5 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Detailed mass budget of the proposed solar panel model. were mounted on the rear surface of the PCB panel through double-sided 3 MTM 966 acrylic tapes [22]. The 3 MTM 966 acrylic tape is a high-temperature adhesive that has been used in aerospace applications that comply with ASTM E596 low volatility specification criteria for space application of the National Aeronautics and Space Administration (NASA). For the attenuation of transmitted launch loads on the panel, the fundamental principle is based on constrained layer damping accomplished by the shear deformation characteristics achieved between interlaminated thin stiffeners and adhesive tapes. The basic specifications of the materials used in the solar panel module are listed in Table 4.  
The stiffener attachment process on the panel is considerably simple, although the uniform bonding strength distribution in the workmanship should be controlled with intensive care. Therefore, for symmetrical attachment and easy integration of the stiffeners, \begin{table}
\begin{tabular}{c c c} \hline \hline
**Item** & **Details** & **Value** \\ \hline \multirow{4}{*}{FR4} & Elastic modulus (Pa) & 18.73 \(\times\) 10\({}^{9}\) \\ \cline{2-3}  & Density (kg/m\({}^{3}\)) & 1850 \\ \cline{2-3}  & Poisson’s ratio & 0.136 \\ \cline{2-3}  & Thermal conductivity (W/mK) & 0.29 \\ \hline \multirow{4}{*}{Adhesive tape [22]} & Manufacturer & 3M Company \\ \cline{2-3}  & Adhesive material & Acrylic \\ \cline{2-3}  & Adhesive thickness (mm) & 0.06 \\ \cline{2-3}  & Color & Transparent \\ \cline{2-3}  & Allowable temperature range (\({}^{\circ}\)C) & \(-\)40 to 232 \\ \cline{2-3}  & Thermal conductivity at 41 \({}^{\circ}\)C (W/mK) & 0.178 \\ \cline{2-3}  & Coefficient of thermal expansion (ppm/\({}^{\circ}\)C) & 1.99 \\ \cline{2-3}  & Adhesive strength to steel (N/100 mm) & 159 \\ \cline{2-3}  & Total mass loss (TML) and Collected volatile & \\ \cline{2-3}  & condensable material (CVCM) outgassing (\%) & 0.93, 0.01 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Specifications of materials used in the solar panel module.