I have said this several times and I will say it again. The entire back of the phone CAN NOT be made of metal. NFC will not function if the back is all metal.
If there is a portion that is non-metallic NFC will work, but if you want it to continue to work, you will not be able to by a case that covers that portion with any sort of metal. Doesn't matter how thin the metal is.
If there is a portion that is non-metallic NFC will work, but if you want it to continue to work, you will not be able to by a case that covers that portion with any sort of metal. Doesn't matter how thin the metal is.