1.6mm and 1mm PCB thickness ?

[QuocTrong]

I don't know why people use PCB with 1.6mm thickness but why not 1mm thickness in most keyboard use daughter board. With 1 mm thickness will be feel flex like as flexcut and without Flexcut in PCB ( maybe right ) , well that why i don't know why 1mm PCB thickness not commonly used ? 
thank everyone read it , Have a good day.

[Vorge]

First and probably the most important thing is that1.6mm PCBs are the standard and I havent seen 1mm thickness available in all of the sites Ive been, 0.8mm is the closest one. Being that thin also may lead them to break easier.

Also most of the boards use a plate which is where most of the flex in a board comes from and the PCB just kinda deals with it. Ive seen some boards use the 0.8mm PCBs so its not impossible to use them or something new, but honestly I dont think that changes the experience in a big way.

This is based on my view and experience, its not "rough data" by any means, so you might wanna use my points just to think about it.

[vutid]

i personally prefer the standard 1.6mm

[aodioxp]

It is more like a strength requirement. Nowadays, 1.2mm PCB is quite common since it is both flex and retain some of the strength needed for hotswap or switching keycaps. I have seen 0.8mm PCB broke by simply removing the keycaps, the PCB part came out with it.
1.2mm is gonna be the mainstream in 2022 since everyone is liking the flex it provides.