I can't really answer the pcb temp tolerance value but you may get some clues from the PCB making process.

At the nearly end of the pcb making process, solder masking (pcb painting --> normal color: green) is needed. In order to dry up the solder mask, pre-cure and post-cure processes are needed which are about 75C and 150C respectively. Under the post-cure process, the pcb is put into a 150C oven for about 30 minutes.

Then, HAL, ENIG or ENTEK is run. For HAL (Hot Air Levelling), it will deposit the soldering iron on the surface of pcb connectors. This process can be run AT MOST 3 times on 230C for single PCB. Whenever the temperature is over that value or the frequency of doing HAL is over 3, there is a posibility that the solder mask may melt or copper foils may burn.

From the above processes, you may assume that any temp below 150C should be safe for a PCB board and 230C is considered a dangerous level. However, if you can achieve that temp level, you can say goodbye to the electronic components on your pcb already.

p/s: The above assumption can be made as long as the solder mask ink quality can meet the industrial standard.