HOT AIR NOZZLE CHOICES... cracking the nut!

[busyfone]

Just using standard round nozzles........
I got this surprise when I was trying to hot air off a small QFN LDO regulator from a Samsung S5 motherboard. At first I was using a 4mm nozzle size thinking that will cover it, it certainly covered the entire area of the chip(and more some). BUT.... I had got up to 50 seconds and still the mother hadn't reflowed! So off goes the heat and without changing anything else up'ed to a 5mm nozzle and off in about 25-30s. WTF?
After this experince and others I'm beginning to think nozzle sizes under 5mm are well... useless. But I'm also thinking larger nozzle sizes tend to spread heat over the entire board quicker. In my current phase of validating hot air skills I haven't been using any nozzle size under 6mm for anything, it certainly makes the board, while soldering hotter overall, but haven't destroyed anything either. Any advice, experience to share regards nozzle sizes?

[Jessa_the_Professa]

I rarely change the nozzle--I use something in the 6-8mm range for nearly everything. I will adapt my style based on whatever nozzle is on the machine. For shield removal I will use a large nozzle 10-12mm, the small ones are too little to spread heat around to drop the shield. I have never attempted to use those tiny nozzles--seems like it would be impractical. You'll notice that store.ipadrehab.com only sells the nozzles that we actually use.