Where do I find the part number for the iPad Mini logic board?

The board number itself typically starts with 820 and the Apple part number starts with 661. The board number is often consistent across storage capacities, but the Apple part number would be different.

iPad and iPhone board numbers can be a bit more elusive than a MacBook for example. Apple loves to put the number under a sticker. In my recollection, iPad board numbers are even more difficult because they are often on the backside of the board.

Based on the info I have, the iPad mini 4 Cellular version has a board number of 820-00177.