Most components are 0603 sized, which I can assemble by hand. I could also use 0402 sized components but I don't think I really need to since space isn't actually running out yet.



I decided on a X mode design, and I thought a 1.5 inch by 1.5 inch square main PCB would be a suitable size. This is because the size of the propellers dictated the motor-to-motor distance, and I thought this main PCB size would be big enough for the components and be small enough to not restrict airflow.



I had the option of designing the "arms" of the quadcopter into the main PCB directly but I didn't think that would be strong enough without making the arms too wide. If they are too wide, then they are not aerodynamic. So I decided the make the arms as separate pieces which would attach to the corners of the "body" PCB using slots. Solder is used to make the connection solid, and also conduct the electrical current for the motors.



The motor arms are milled by the PCB manufacture, so I had to provide the outline. The motors had to be purchased first, then I measured the dimensions of the motors myself so I can design the arms correctly.



The motor control circuitry are placed near the corners, this is just a minor detail and made routing easier for me.



The antenna for the transmitter will be a RP-SMA connector on the edge of the PCB, which will be connected to a 2.4 GHz duck antenna, just like the ones on Wifi routers. I don't care about weight on the transmitter since it's not flying, so I might as well get a good performing antenna.



The antenna for the quadcopter itself is a lightweight and tiny chip antenna, placed near the edge and without any copper planes under and around it.



The radio circuit has to be really close to the microcontroller. 1.6 mm thick FR4 PCB is not the greatest for making traces with good impedance (we want 50 ohms), but the power lost from impedance mismatch is negligible if the trace length is much shorter than 1/4th of the signal's wave length. I still tried to make sure the balanced traces are equal length and thick to match the impedance better.



When you design capacitors into your schematic, remember that they need to be physically close to the component they are meant for. The capacitors for the radio circuitry are also designed for high frequency with low ESR.



The crystal also needs to be close to the microcontroller.



There is a small power switch for the transmitter, and a shunt block jumper acts as a switch for the quadcopter.



The battery connectors are polarized JST connectors so you can't plug them in backwards.



The connector for the Wii Classic Controller is designed right into the PCB. 1.6 mm thick PCB is perfect for this job.



The reason why I designed the transmitter PCB and quadcopter PCB into one solid piece is because I thought it'll be easier and cheaper to assemble. This turned out to be a horrible idea. "Version 2" was designed as two separate pieces.



Some mounting holes are always nice. #4-40 is a good sized screw for this job. Keep the area clear around the holes because you'll need to put nuts there. I planned on making a plastic case out of sheets of plastic, which will attach to these holes.



Once the design is finished, use EAGLE's CAM processor to run the ".cam" file as a job, which should generate Gerber files that you can send to a PCB manufacture. Remember to double check your Gerber files using a Gerber file preview tool. Also print out 1:1 scale copies of your design so you can check the footprints and dimensions. Make sure you pay attention to the text size as well.



I wanted to do circuit assembly using a solder paste stencil and reflow soldering so I also have to pay attention to the solder paste layer in my design. "Version 1" was completely assembled using a solder paste stencil and reflow soldering oven, "version 2" was assembled using a heat gun and traditional soldering iron (no time to get another stencil made).

