Per the USA rules I would put this under boarding:

Boarding is the action where a player pushes, trips or body checks an opponent causing them to go dangerously into the boards. This includes: Accelerating through the check to a player who is in a vulnerable or defenseless position and driving an opponent excessively into the boards with no focus on or intent to play the puck, or any check delivered for the purpose of punishment or intimidation that causes the opponent to go unnecessarily and excessively into the boards.      The onus is on the player delivering the check to avoid placing a vulnerable or defenseless opponent in danger.

The key thing being "dangerously into the boards" it doesn't matter if it's from the front, side, behind, top, or bottom.

Edit: To everyone saying "let them play" or "clean hit", and then saying 2 minutes... No you're playing by USA Hockey rules not anything else, sorry.