Why are my breaks squealing?

I have a 98 Mustang GT. Recently I had a blown caliper on the rear braking system, fixed it about 3 weeks ago now I have a squeal coming from (sounds like) the front. It happens when I lightly touch the brake pedal, if I depress it more aggressively it doesn't make noise. I have pulled it apart because I originally thought it was the squealers on the front pads making contact with the rotor, that's when I found out that the pads don't have squealers and they also have plenty left on them. My rotors don't look or feel warped and I even re-checked my rear brakes and everything seems normal. I've pretty well exhausted my knowledge at this point so any input is greatly appreciated (unless it's a joke about Fords) :)!

Thanks

Added (1). I use semi-metallic pads

You can also get the squealing from loose brake dust or other debris that gets trapped between the caliper and the disks. Give it all a really good clean with dry rags and things should improve.

It's the brand of brake friction material you're using. If the brakes are lacking anti-vibration shims, new anti-rattle clips and ceramic friction material they will howl when you use the brakes every time.

This is not a Ford joke but it's impossible to "feel" warped brake rotors. Rotor run-out has to be checked with a magnetic base fixture with a 0-1 dial indicator. More than.003 run out means the rotors go in the scrap pile. Warped brake rotors do not cause brakes to "squeak".