Poor Man PCB Assembly

The following is My Poor Man’s Method to assemble a printed circuit board using only a SMD Hot Air Soldering Station, Flux Paste, SN60pb40 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:

  1. Using a Q-tip, apply a thin layer of soldering flux paste (not solder paste) to the board surface.
  2. Using a soldering iron and solder wire, tin the pads.
  3. Place ONE component at a time (start with the critical and more complicated components first). I.E. MPU6050,  switching regulator.
  4. 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.
  5. Move to the next component and repeat step 4.
  6. 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.
  7. 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.
  8. 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.
  9. Check for shorts (continuity) with a multi-meter before powering up. Then, Power the board up!
  10. 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.