Arduino Motorized SMT Solder Paste Dispenser

cults3d

This motorized solder paste dispenser for SMT boards was inspired by the BD syringe based design found on thingiverse.com. The project's home directory is located on github at https://github.com/zapta/misc/tree/master/paste_injector, where you can find both hardware and firmware designs of a compatible controller board that looks to the Arduino IDE like an Arduino Pro Mini. Schematic: https://github.com/zapta/misc/raw/master/paste_injector/eagle/paste_injector_schematic.pdf BOM: https://github.com/zapta/misc/blob/master/paste_injector/eagle/paste_injector_bom.csv EEVBLOG discussion:http://www.eevblog.com/forum/reviews/solder-pasteflux-manual-syringe-applicator/150/ I successfully printed this design using both PLA and ABS with standard slicing parameters (3 layer shells, 20% infill). Hints: Make sure to have high extruder temperatures when printing the motor axis coupler for good inter-layer bonding. The step motor listed in the BOM can be found on eBay from many sellers. They often come with a ULN2003 driver PCB that is not needed here. When mounting the coupler on the motor, try to minimize free play along the motor axis. I used a sharp knife to pull out the motor axis while pushing the coupler toward the motor before tightening the coupler screws. You can insert threaded inserts using any standard solder iron that fits into their holes. It's best to use tapered inserts similar to those specified in the BOM. If not, taper them using a file or Dremel tool, especially for the plunger rod insert. Don't push the inserts too hard; let heat do most of the work for better adhesion. I programmed the controller board using an AVRISP MKII, but you can use whatever works for you. Github has the binary image file with the Arduino bootloader and a script that programs the AVR fuses. If you want to hack the firmware, solder a 6 pin header at the FTDI marked pads and use an adapter such as FTDI Basic to hook up the controller to your computer. Solder paste lasts longer when stored in a cool place. I store my dispenser in a plastic bag and put it in the fridge (not the freezer). When storing solder paste, remove the needle and close it with a Luer Lock cap, which can be found on amazon and ebay. If you keep using the same needle, make sure to clean it after each usage by flushing it with IPA.