My wife had mentioned about a noise coming from rear brakes a while back but it was intermittent and after visually inspecting it and driving it I decided to put the repair on hold until I need to replace the pads. Well, last night on the way home she heard grinding and banging from the rear wheel , but got home regardless. I took it apart this morning and I am not impressed with myself. By not thoroughly inspecting the brakes in the first place I think I will now have to replace the knuckle (the brake shoe rest block sheared) and the e-brake cable along with all the hardware. Not really sure why it fell apart though, it was a Florida car rust should not be an issue?

 

This has been an issue with the rear brake shoes. What happens is the parking brake shoe de-laminates from the backing plate.
There are many pictures like yours on the other Volvo forums.
Sorry about your luck.