I thought there's no difference.
You're not thinking of drag soldering, are you?
Drag soldering with multiple IC pins for sure: 63/37. You tack two corners and drag the solder across the pins. With 60/40, you tend to short the pins. My very FIRST experience with SMD soldering/removal was a processor chip in a car radio.
I also soldered it inverted which helped.
I just hate Sn96. I really do. I used it to solder the lower probe:
Not the probe needles. Initially I soldered the wires (Teflon insulated). The manufacturer,
www.Accuprobe.com, initially welded the ceramic PCB to the probe body and Sn96 for the needles. Then they changed to 60/40 for the PCB and the probes fell apart. The manufacturer was willing to use Sn96 for us.
The lower probe is actually two probe tips, one on each side of the ceramic PCB. One connection is the probe body and the other would be the green wire.
First, I had to make a jig (a vise) to hold the PCB and the probe body. I made it from a piece 1" of C channel aluminum and 4 cap screws.
I milled a slot in the side so I could see where to position the pieces.
I also had to boil the probes in baking soda for 10 minutes to remove the flux they missed and then electroless gold plate.
I used the modified probes from -80C to 200C.
For the SMD parts, non-magnetic tweezers or a vacuum tool. Hold down the part with a toothpick or similar non-magnetic tool.
Hold until it cools.
There are component adhesives to assist in soldering PCB components.