Population and Soldering

A project log for General Purpose Software Defined Transmitter

GPSDTx is a board capable of transmitting a signal up to a few MHz (1-3?) wide anywhere between 100MHz and 2.2GHz

Brett KillionBrett Killion 12/07/2016 at 22:010 Comments

This was my first foray into reflow soldering my SMD parts and also my first time using a stencil for paste application. Wow is that a nice process over hand soldering dozens of 0603 resistors and capacitors and other chips.

The paste application went very smoothly. I used the extra boards taped to the table as a makeshift frame, lined up the stencil and taped it down (on one edge, so the tape acted as a hinge) and then smeared some paste with an old credit card. I ended up having a little too much paste on a few microcontroller pins and on some of the QFN package pins as well and had some solder bridges to clean up, but otherwise it was great. Those bridges can probably be attributed to not enough or uneven pressure during the smear.

Placement was a little rough as I don't have a nice pair of tweezers and instead was using an old and slightly bent pair of forceps, but I got the components place. There were 109 parts and it took me about 45-50 minutes to place them all by hand.

I then pulled out my brand new reflow oven ($30 toaster oven), set the populated board on the rack, and turned it on as high as it would go. It took about 4 minutes before the solder paste melted. After waiting another 20-30 seconds, I turned the toaster off and cracked the door slightly to start it cooling. After about 10 minutes, I had a nice board, and as mentioned above, only had a few solder bridges to deal with.