Mid grade Boards

Can anybody give me an example or two of a mid-grade board and a Peripheral

I think it's subjective. It's best to talk with your buyer to see how he/she grades their boards.

Personally ... i look at the value items on the board and balance that against the things that detract from it's value. Tracings are a factor in the mix as well.

If you dig through the weeds there are a lot of threads that deal with identifying the value items on a board. It's best to spend a little time learning about what all the different pieces are, what they do, and whether or not they have trace amounts of PM's in them.

Boardsort has a forum with an identification section. Look at enough boards and soak in the "why" and you will learn some. EWasteBen on youtube has some good videos as well for this sort of thing.

I think generally mid and periph are roughly the same grade depending on who you are talking to. Printer main boards, tv brains boards, modem boards, cable box boards...that kind of thing. You want a strong layered board as opposed to a breakable low grade board, with usually at least one decent sized or several smaller flatpack or at least one BGA chip.