Soldering small laser parts is different than "normal" soldering
This method is also used when making wire-to-wire solders with small wire
Soldering diode pins takes a fraction of a second
Pre-tin BOTH the pins and the wire or solder pads
Use a small bit of flux on BOTH the pins and the wires/pads BOTH for the pre-tin and the final solder joint
I don't care if you use rosin core solder. USE THE FLUX!
Use a set of "extra hands" to align the pin with the wire/pad.
Make sure that they are side-by-side, touching, and secure
Get a small bit of solder on the tip of your soldering iron
"Touch" the melted solder on your iron to the pin to wire/pad joint
The solder will all flow together in a fraction of a second.
I recommend that you also use some shrink tubing to protect and reinforce the joint
You DO NOT "heat the joint" as with other solder jobs
You DO NOT place the solder source anywhere near the solder job
Only the melted solder on the tip of your iron should approach the pin to wire/pad joint
Practice the above procedure until you can get a good solder in a fraction of a second.
Peace,
dave