How do Boards punishment lines up before being permanently banned from Boards?

The last time I had been suspended was for 7 days (due to using the DS word on an imaginary player), and now, I may have posted an immature thread that made Riot deleted it.

May I have a Rioter to tell me where and when is the punishment severe enough to be pushed into a permanent ban from Boards? I just want to be a little more careful about what I post :p