Okay. So if we assume that it's marketing speak, or even if it doesn't matter, there are still two possible scenarios:
1. What they claim is true.
2. What they claim is false.
Although I believe the former, let's suppose for a second that the latter is true. That means that every single large industrial customer of said companies, that might have thousands of their stations and following their guidelines, is going to be soldering at an incorrect temperature, leading to many failures and so on. Eventually, the problem will be traced back to the manufacturer of the soldering stations, leading to widespread lawsuits/recalls/etc. Odd that we haven't heard of those, however.
But let's set that aside for a moment and look at some non-affiliated examples, out of interest:
IPC, who develops the vast majority of the standards used in the industry, as well as certifications has the following to say on the matter in one of their training courses:
As stated previously, the melting temperatures are up to 40 degrees C higher. For example, a soldering iron temperature for a lead-free process may be 400 degrees C versus 360 degrees C for tin-lead.
...
Now, let’s take a look at the soldering operation. For this example we’ll use a tin-silver-copper alloy that has a melting temperature of 217 degrees C. We’ll be using a temperature- controlled
soldering iron with a chisel tip. The temperature will be set at 410 degrees C
Higher than the soldering equipment manufacturers ask for, but we don't know which irons are used for this particular training (AFAIK, they used older model Pace stations that weren't as good, however). Still, not 450C.
Kester, on lead-free hand soldering. Error and typo prone, but I figured I'd link it anyway:
What is the best soldering tip temperature for lead-free SAC and SnCu?
The temperature of the tip or contact temperature is very important to ease the lead-free hand-soldering operation. When using 63/37 solders temperatures as low as 650ºF have been used but with lead-free 700-800ºF is best. The higher temperature does compensate for the slower wetting exhibited with these lead-free alloys. Above 800ºF issues of board and component damage may arise; at lower temperatures cold solder joints and flagging are the normal complaints.
...
ƒInsure the tips are designed for lead-free
Insure the temperature is set to 700-800 ºF
So, about 370C - 425C. Still not 450, and specifically warns against it. No indication of what iron was used.
Eptac, another IPC and JEDEC certification trainer:
There are two factors involved in making this selection, one being the mass of the metal being joined and second the size of the soldering iron tip.
As for the alloy being used, the 63/37 is liquidus at 183C and the new RoHS alloys, such as SAC305 and Sn100C have a liquidus temperature around 215C. With the soldering iron set at between 371C [700F] and 398C [750F], one should be able to solder most joints. If the mass of the joints is very small then the temperature of the solder iron could be reduced to 343C [650F].
It is recommended to use the lowest possible temperature which will reflow the total joint, as using higher temperatures will create more damage to the tip of the soldering iron which will increase tooling cost.
These temperatures are satisfactory for all alloys, be it either the standard Sn/Pb or the new Lead-free alloys such as SAC 305 and Sn100C.
No specific soldering iron being referenced.
IPC again, this time a newer and updated course:
For leadfree alloys, a good starting point is 350 degrees C, or 662 degrees F. Variations in the alloy, either tin-lead, or lead-free, will require variations to the starting point temperatures.
...
After we’ve prepared the tip of the soldering iron, we should be ready to start the soldering operation. We'll be using a temperature controlled soldering iron with a chisel tip. The temperature of the tip will be set at 315 degrees C, or 600 degrees F for tin-lead solder – and about 350 degrees C, or 662 degrees F for lead free solder.
...
Now, we’ll demonstrate the same soldering technique using lead free solder. The main difference is that lead free has a higher melting temperature than tin-lead – so instead of a starting temperature of 315 degrees C, we’ll set the temperature at 350 degrees C.
The course is
listed as being demonstrated by a person from Pace, so one assumes that a more up to date Pace station is used.
ACI, a company specializing in IPC training, in particular for the DOD (Navy and Army):
Lead-free solder alloys generally have higher melting points. Therefore, the solder tip must be set to a higher temperature. For example, when using the lead-free solder alloy, tin silver copper (SAC-305), it was determined that the solder tip had to be set to 343°C / 650°F, as opposed to 315°C / 600°F for tin-lead (SnPb).
Solder iron shown in the picture appears to be a Metcal.
A Linkedin discussion of the topic, between people involved in the industry, quote is from a certification instructor:
When I teach J-STD-001 or IPC-7711-7721, I start the students at 600°F for Sn/Pb and 650°F for SAC305 when learning on the standard IPC circuit board. However, our company work instructions are sometimes customized for the factors mentioned above. I find that component and PCB damage usually occurs when the operator compensates for the factors (poor soldering) by turning the temperature up where the control base allow (my favorite bases are from OKi / Metcal that doesn't allow operator manipulation) or by using a tip that is too large (actual temperature can deviate +25-50°F higher than indicated on the base, when measured with pyrometer). In this area, Gerald's advice is vital - quality of the tools matter.
That's ~350C. Metcal is referenced.
So, there seems to be at least some pattern of where a quality iron is used, the temperature reduction for lead-free hand soldering is achieved, lending credence to manufacturer claims. Even when the iron is unknown, nobody used 450C and specifically warned against it. All sources are what I'd personally consider authoritative on the subject matter, having significant impact in the industry.
All I'm trying to do is to prevent people from damaging their tips, equipment and components trying this at 450C with cheap stations. I'm not sure what other proof I need, other than perhaps demonstrating lead-free soldering myself at mentioned lower temperatures. I do have stations from Pace/JBC/Metcal as well as cheaper Hakko heater type stations for comparison at same temps, though I am lacking in lead-free solder - but that's easy to fix.