Designing the Frame in AutoCAD:

 

• Start by creating the basic drone frame using lines and circles (ensure the units are set to mm). Include a symmetrical line to ensure even component placement, which simplifies the drone’s control algorithm and enhances stability. Add rounded edges to improve the frame’s durability. Select the drone size based on the propeller, with sizes such as 40mm, 55mm, and 65mm available. For the 8520 motors, 55mm is the most suitable choice.

• Once the design is complete, add an outer square measuring 10×10 cm and save the file in the .dxf format.

Circuit Design in EASYEDA:

 

• Proceed to design the circuit in EASYEDA.
• Create a new project and begin drafting the schematic.
• Use the net port feature to keep the schematic neat and organized.

• Once the schematic is complete, click on “Design” → “Convert Schematic to PCB.
• Perform a DRC check to verify the schematic and ensure there are no errors or warnings.

Importing the DXF File into EASYEDA:

 

• Once the PCB layout is designed, you can import the diagram from AutoCAD.
• Go to “File” → “Import” → “DXF.”

• Select the .dxf drawing file.

• Ensure that the layer type is set to BoardOutLine and the stroke width is 0.245 mm.
• Enable the Convert Circle to Hole on BoardOutLine checkbox to create mounting holes for the motors.
• Arrange components symmetrically to maintain balance.
• Place the MOSFET near the motor to improve cooling via airflow from the propeller during flight.
• Position the IMU as close to the center as possible to improve stability and reduce algorithm complexity.
• Add a silk-screen arrow mark to indicate the front of the drone, which aids during flight.
• Add a circular arrow mark to show the motor’s rotation direction, helping during motor installation.

• Remove the symmetrical line once component placement is complete.
• Route all traces, either manually or using AutoRouter. Manual routing is recommended for better control.
• Increase the width of the power traces to handle higher current.
• Each motor can draw up to 2A, and with a 0.25mm trace width, the trace could overheat. Use a trace width between 0.4mm and 1mm for motor power lines.

• Use the 2D or 3D view feature to inspect the final PCB layout.
• Add terminal markings in the silk screen layer to prevent incorrect polarity connections during assembly.

• Once you are satisfied with the final PCB design, export the Gerber file by selecting “File” → “Generate PCB Fabrication File (Gerber)…”.
• Perform a final DRC check to ensure the design is error-free.
• Upload the Gerber file to WellCircuits and choose a PCB thickness of 1.2mm.
• We’ve tested PCB thicknesses of 1mm, 1.2mm, and 1.6mm. While 1.6mm is a standard choice, it adds weight to the drone. Thinner PCBs (less than 1mm) provide more flexibility, which could make the drone more fragile. Therefore, 1.2mm is the optimal balance between weight, strength, and flexibility.
• During field testing, the 1.2mm PCB survived multiple crashes with minimal damage, mainly around the arm area.
• Check out this video for tips on soldering and programming the PCB.
• This guide should give you a solid understanding of how to design a custom-shaped PCB for your drone.

If you have any questions about PCB and PCBA, please feel free to contact me at info@wellcircuits.com.