Squeaky brakes are a result of a combination of metal to metal harmonic vibrations...

You can cure this by using a vibration dampening agent...on my Beemer Bikes I ALWAYS, when changing pads, put a small dab of brake caliper grease on the back of the pad that meets the caliper piston..

This in effect acts as a vibration damening agent and works like a charm...!

NOTE DO NOT UNDER ANY CIRCUMSTANCE GET ANY OF THE AGENT NO MATTER WHAT TYPE, BUT SPECIFICALLY THE GREASE ON THE ROTOR OR PAD !..YMMV...

Later

Nick