So last week after the anti-static table mats arrived I set about cleaning one of the pcbs and taping two L brackets unto my table before setting the PCB atop it and then clamping down the stencil. I applied the CHEAPO XG-50 solder paste (I bought from China on Ebay)
The second application came out much better than the first. It still took over 3 hours (I would stop and play with my son, grab a snatch, check emails, watch a movie) before I mounted the parts.
Then followed the following procedure (which was wrong) to reflow the board:
Brought the hotplate to 180 degrees. set the PCB board atop it and crank up the temperature to 230 degrees and after it looks like the solder paste has reflowed - remove the board and turn off the hotplate.
The right procedure I learned from a colleague at work should be something like this.
Bring the hotplate to 180 degrees (next time measure this with IR temperature sensor).
Set the PCB board atop it and crank up the temperature to 200 degrees.
After a minute or so - remove the board and turn off the hotplate.
Set a fan to cool the board down ASAP
I may still be able to rescue this failed attempt using a heat gun. But I am eager to try again using
1) lead free solder with low temperature
2) table magnifying glass to better allow me to place components after solder paste has been applied
