Sqeaky brahes are inevitably caused by a build up of brake dust within the caliper as the lining of the pad wears. Manufacturers use softer compounds these days for more efficient braking. This leads to faster wear and a quicker build up of dust. You can strip them and clean them, but I usually go the jet-wash when mine start and get the nozzle right into, and around the brake caliper to blast it all out. Works well.