I'm pretty used to just blindly specifying high-Tg 170C or greater on my complex multi-layer boards. I do understand what the rating means and have a general idea that higher Tg means they'll survive in the oven at higher temperatures (like for RoHS process).
Anyway I was quoting a tiny 1" x 0.5" 4 layer PCB and the cost difference between Tg 150 and Tg 170 was about 10x for my run. So I'm inclined to go with Tg 150 :) But I'm not sure of myself.
What should I watch out for here? Or maybe better what questions should I be asking myself about my design to ensure I can pick 150Tg with confidence? Max ambient is 55C and the board doesn't generate much heat, maybe an additional 10C rise. I don't have to use RoHS compliant process I just do because it's nicer to the environment.
I did do some reading and googling but didn't really find what I was looking for.