The following is My Poor Man’s Method to assemble a printed circuit board using only a hot air soldering station, flux, rosin core solder wire, a toothbrush, 91% Isopropyl alcohol, 900M-T-B soldering tip, and curved ESD-15 tweezers. Just for fun and to show what is possible, I’ve used this method on the prototypes pictured on this site.
NOTE: Make sure your work area is well ventilated. I.E. Use a fan to suck fumes away from you. Open a window, and face the fan in that direction.
The Poor Man PCB Assembly Process:
- Using a Q-tip, apply a thin layer of soldering flux paste (not solder paste) to the board surface.
- Using a soldering iron and solder wire, tin the pads.
- Place ONE component at a time (start with the critical and more complicated components first). I.E. MPU6050, switching regulator.
- Using the hot air gun, apply heat until the solder liquifies and the component drops into place on it’s pads. -> Study reflow videos to learn how to do this.
- Move to the next component and repeat step 4.
- Once finished with component placement and adhesion, use the Q-tip to apply more flux to the edges of the MCU, regulator, and MPU6050 chips. Don’t be sparse – saturate the area with flux.
- Tin your soldering tip. Then slowly drag the tip of the soldering iron across the pins and edges of the critical chips to remove any solder bridging and to form a solid solder joint between the component and pads. Let the flux work for you.
- Using a toothbrush (set aside for this purpose only), and 91% rubbing alcohol, dip the toothbrush in the bottle of alcohol. Scrub the board with the toothbrush to remove the flux residue. Air dry.
- Check for shorts (continuity) with a multi-meter before powering up. Then, Power the board up!
- If all goes well, you should be able to proceed to jump the boot pins and prepare to flash the board with firmware.
SIDE NOTES: It helps to apply flux and tin the pads of some component parts during Steps 1-2 to achieve better adhesion. I do this on the USB plug, MPU6050, and regulator.
To access all side/pad/pin ends of critical components, sometimes it is necessary to leave simple parts (capacitors, resistors, etc) surrounding those critical parts off until after those side/pad/pin ends have been drag soldered. The MPU sensor and regulator are prime examples.