Fabricating a circuitboard using acid etching and SMT components:
Seeing as we completed the acid etching phase in class, it was left to us to complete assembly of the boards in our own time. Operating on the assumption that it's best practice to use solder mask when fabricating boards with SMT components, I decided to incorporate it into the process for the sake of learning. The images below outline process following the completion of the acid etching:
The process is as follows:
> remove the protective film from the matte side of the solder mask and apply it to the board.
> send it through the laminator 3-5 times.
> place the printed transparency overlay onto the board.
> cure for 30seconds under UV light.
> remove solder mask from pads using a NaCl solution and a toothbrush.
> place under UV light for an additional 7 seconds.
> apply solder paste using the stencil that was cut using the laser cutter.
> place the components using the pick-n-place machine.
> melt the solder using the heat gun (at around 240 degrees C).
> check the connections using the microscope.
> test parts