Many times on auto disk brakes the squeal is caused by a vibration btw the piston and the back side of the pad. NAPA has stuff you can paint on the back of the pads, let it dry and re-install. I have an old Volvo, used to squeal all the time. The brake stuff worked. Now when you buy new pads for most cars they include a thin metal shim that goes btw the piston and the pad and it is there to stop the squeal. I'd try the brake squeak stuff or see if with new pads they include the shim. Either way you will have to pull the pads so might as well change them if they close to being worn out.