2012 Speedy Front Caliper Nm Question

I would not put any copper grease on the back of the pads, even when used sparingly it attracts road grit and dirt, this in turn acts in a very abrasive manner and in no time at all the brake pistons become pitted, it may be worthwhile taking the pads out and thoroughly clean the calipers, if the pads are serviceable then just de glaze them, also by putting copper slip on the rear of the pads it can and does find it's way onto the pad material, often brake squeal is down to the age of the pads as the material hardens off excessively.