I've been told that pads and rotors on Mercedes need to replaced at the same time to prevent squealing.
Further, that anit-squeal grease is always applied to the back of the pad to prevent noise.
2001 E430, Bourdeaux Red, Oyster interior.
1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".