The brakes on my sons 88 240DL wagon squeak like you can't believe! He has but new pads on and the rotors look ok.
Any suggestions to address the menacing squeak...?
look up "rotor glazing"
Not familiar with Volvo brakes... do they need shims and/or clips to not rub in unwanted ways? Squeal isn't always a rotor surface to pad surface issue.
Do you live in a quarry? (sounds silly but really dusty environments can cause squeal).
Agree with all of the above. Glazing, especially on certain, often cheaper (but not always) pads, can get noisy. Check the net or maybe an enthusiast forum for a (downloadable?) copy of the factory Service manual. Sometimes there are even trouble-shooting sections that might address the issue. It should also provide the minimum thickness of the rotor which you need to know before having them turned. Worse case scenario is just get replacement rotors. But you can’t always see run-out or judge them visually.
And if shimmed, sometimes the shims require a little brake grease.