Up to this point I have hand soldered all my boards. This can be pretty difficult when soldering a fine pitch IC (TQFP) but it’s do-able. Anyways, I have created my first board for work and decided that I would reflow it. I ordered a jar of solder paste, had a mylar stencil (4 mils thick) made to match the pads on my PCB, bought a putty knife (Home Depot special) and bought a skillet from Target (24.99 on sale!). I made a jig from some crap PCBs and 1/8″ sheet of aluminum so that as I pulled back with the putty knife the board would not move on me. I dropped a nice spoonfull of solder pasted on the stencil and positioned it over the board. Using one hand to keep the stencil in place I pulled the paste towards me across the entire board. It worked like a champ! The paste was evenly distributed across the pads and ONLY on the pads. Using a set of fine tweezers I placed all components (50+) on the board within 15 minutes. I dropped it on the skillet and brought it up to 250F for a few minutes and then ramped up to 400F. I waited a few minutes and finally the paste hit the melting point, turning from a dull gray to a shiny silver. I gave it another 30 second or so as it seemed the temperature was not uniform across the entire PCB. It’s really cool to watch the paste melt and the components orient themselves. You can place the component with a great deal of mis-alignment and it will right itself. Another bonus is the silkscreen on the backside didn’t discolor at all. Pretty cool huh?

Even cooler is the new hot air rework gun Surfx purchased. I fried a 44 pin TQFP IC because of a stupid footprint mistake. Replacing this with a soldering iron would be nearly impossible. With the hot air gun I apply a shot of 360C air to that portion of the PCB for about 20 seconds a the chip pops right off. Replacing and reflowing the IC is just as simple.

Cool new stuff..