Quick question: Is there a particular kind of solder that works better than others for soldering to the I2S pads? I'm trying to use some flux core solder and I'm having trouble getting the solder to stick to the solder on the pads.

It could just be my technique as well. I tinned the wire and am just trying to touch the wire to the pad with the iron until it gets hot enough to flow and then remove the iron, but then the wire just doesn't stick after the solder cools.