# 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
### Solar Panel Holding and Release Mechanism
(PC817) [27] transmits electrical signals by light between two electrically isolated circuits, thus preventing high-voltage electrical malfunctions in the circuit. The power cutoff function on the mechanism is accomplished instantly after the deployment of the solar panel with the electrical circuit shown in the block diagram without employing a microcontroller unit (MCU). Figure 7a,b illustrate resistor PCB's front and rear views, respectively. A resistor as an actuator for solar panel release is soldered on the front side of the resistor PCB, which faces the outward direction while integrating on the solar panel. To interconnect the electrical power coming from the pogo pins to the resistor, three surface-mounted electrodes were attached to the rear surface of the resistor PCB that was mechanically connected to the resistor internally. Additionally, two via hole interfaces were made near the electrodes that were physically connected to the electrodes. In general, thermal vias are well-known methods used to enhance the heat dissipation of surface-mounted components in a PCB. However, the application of vias in the resistor PCB is to make electrodes more securely attached to the PCB surface in order to avoid the risk of electrode pad detachment due to pogo pin friction under launch vibration loads. [PERSON] et al. [24] performed a  
Figure 6: Three-pogo pin-based mechanism’s electrical system: (**a**) front and rear view of electrical interface PCB (dimensions: 34 mm \(\times\) 16 mm \(\times\) 1 mm) (**b**) schematic block diagram. scanning electron microscope (SEM) inspection of the electrode pads after completing all the vibration tests to evaluate the frictional impact or damage caused by the tip of the pogo pins, even though the spring-loaded pin has a low friction impact on vibration loads. The thickness of the electrical contact part or curvature tip on the electrodes was only reduced by 23.88% compared to that of the 60.37 \(\upmu\)m initial thickness. The frictional impact on the electrode under vibration load is minimal; thus, a secure physical contact can be assured even after being exposed to severe launch vibration loads because of the 1.7 mm full stroke of the spring-loaded pin of the pogo pins. In the mechanism, pogo pins with the combination of voltage resistor divider are used to determine the panel deployment status, which provides telemetry of \"1\" or \"0\" through a buffer IC based on the current flow status in the resistor's circuit path, where \"1\" implies voltage resistor divider's output voltage. Table 6 lists the truth tables of the circuit. Once the mechanism is activated, the current flows through the resistor and the voltage resistor divider. The output voltage at the voltage resistor divider becomes approximately 0 V until the panel is deployed because the resistance value of the resistors used in the voltage resistor divider is significantly higher than that of the resistor used as an actuator for panel deployment. The electrical circuit over the resistor becomes open once the solar panel is deployed such that the output signal of the circuit becomes high, which confirms the deployment status of the solar panel. Therefore, compared to the mechanism [28], the P-HRM proposed in this study has a relatively simpler electrical circuit and is well suited to the available P-POD lateral edge gap.