I cannot imagine anyone soldering with SAC at 300ºC. Not even leaded solder with pre-heating as merely an option. But somehow those values crop up from time to time.
I'm not going to debate them though, I'll just dump my values, it might help someone.
My job involves soldering at least once a week from through-holes to SMDs(mostly), 1.6mm to 0.8mm pcb thickness, from 1206 smd to 0402 (imperial) sizes. From flimsy 0402 resistors to beefy 1cm² all metal casing inductors from hell.
To do all this I use a JBC soldering station with C245 and C210 tips. I also use a non-brand hot-air station for TSSOP ICs with exposed pad on the underside for heat transfer. Sometimes I use a hot-plate as well, and a reflow oven while we're at it.
On the JBC:
For leaded solder: 350ºC on both C245 and C210 tips. I do increase it to +/- 360ºC on occasion to solder near big stubborn ground planes on the pcb. Less than that is impossible without pre-heating because I can't afford to spend more than a few seconds on each soldering op, both because have other things to do and because I can't overheat components. Overheating is also dependent on the time you spend on each component. Might bump it up to 380ºC on those inductors and switch the tips to beefier ones like the chisels and the knives.
For unleaded SAC: 360ºC to 380ºC on those same tips, and I might bump it up to 400ºC again on those inductors.
On the hot-air station:
For leaded: 275ºC
For SAC: 282ºC
On the hotplate: 240ºC for both SAC and leaded. (Mostly repair work after pcbs come out of the oven.)
On the oven: It's a temperature curve and I only use leaded solder paste. Peak at 240ºC.
NOTE1: All the soldering wire I use is flux cored. I tend to use extra flux a lot (Chipquik SMD291), even if it's not really necessary. But on lead-free SAC it's always obligatory.
NOTE2: We don't have any fancy setup where I work and it's overall barely professional in my opinion. Pre-heating is not used much if at all so, I don't have any temperature values to share in that regard.
NOTE3: The SAC solder wire I use is Sn99Cu0,7Ag0,3 EVO11 from CYNEL. I like the brand but I feel the need to try other formulations for different use-cases so I can get away with using lower temperatures on specific temperature sensitive components. On leaded I don't feel that need at all.
It's curious how you use such a big temperature range. I've never used a pinecil despite having friends telling me very good things about it, which picked my interest a bit.
Can you tell us what exactly do you solder at 320ºC and what is the exact type of solder you use and/or Pb and Sn percentages?
Also, is your pinecil calibrated? And which tips do you use at that temperature?
Anecdotally, what usually happens to me at lower temps is the tip and/or the solder wire sticking a bit while I'm soldering which I take as a sign that the liquid solder won't flow correctly and that I have to spend more time giving it heat from tip, than I should.
I use 63/37 solder with a flux core. The Pinecil is amazing, it holds heat really well and gets to 320 C in eight seconds. I didn't calibrate my tip in boiling water, and I don't remember which tip I use now, it's the one that comes by default (B2?).
I only bump it up to 400 C because that was the default, I never use it for more than two or three seconds so the temperature hasn't mattered much. I haven't noticed solder stick, it just sometimes fail to melt properly with large ground planes, so that's when I bump the heat.
I'm not going to debate them though, I'll just dump my values, it might help someone.
My job involves soldering at least once a week from through-holes to SMDs(mostly), 1.6mm to 0.8mm pcb thickness, from 1206 smd to 0402 (imperial) sizes. From flimsy 0402 resistors to beefy 1cm² all metal casing inductors from hell.
To do all this I use a JBC soldering station with C245 and C210 tips. I also use a non-brand hot-air station for TSSOP ICs with exposed pad on the underside for heat transfer. Sometimes I use a hot-plate as well, and a reflow oven while we're at it.
On the JBC:
For leaded solder: 350ºC on both C245 and C210 tips. I do increase it to +/- 360ºC on occasion to solder near big stubborn ground planes on the pcb. Less than that is impossible without pre-heating because I can't afford to spend more than a few seconds on each soldering op, both because have other things to do and because I can't overheat components. Overheating is also dependent on the time you spend on each component. Might bump it up to 380ºC on those inductors and switch the tips to beefier ones like the chisels and the knives.
For unleaded SAC: 360ºC to 380ºC on those same tips, and I might bump it up to 400ºC again on those inductors.
On the hot-air station:
For leaded: 275ºC
For SAC: 282ºC
On the hotplate: 240ºC for both SAC and leaded. (Mostly repair work after pcbs come out of the oven.)
On the oven: It's a temperature curve and I only use leaded solder paste. Peak at 240ºC.
NOTE1: All the soldering wire I use is flux cored. I tend to use extra flux a lot (Chipquik SMD291), even if it's not really necessary. But on lead-free SAC it's always obligatory.
NOTE2: We don't have any fancy setup where I work and it's overall barely professional in my opinion. Pre-heating is not used much if at all so, I don't have any temperature values to share in that regard.
NOTE3: The SAC solder wire I use is Sn99Cu0,7Ag0,3 EVO11 from CYNEL. I like the brand but I feel the need to try other formulations for different use-cases so I can get away with using lower temperatures on specific temperature sensitive components. On leaded I don't feel that need at all.