Did the pads have the little sheet metal anti-squeal things on the back of them? Those are important. If they are supposed to have the sheet metal thing on the back and they don't, they will make bad noises.
The Napa lifetime pads I put on my wife's Nissan make horrible metal on metal noises all the time, but there is nothing wrong with them. Semi-metallic and ceramic pads just make lots of noise. Organic compound pads aren't as bad, but usually make a lot more brake dust.
I'd also do what rollover suggested--make sure your calipers are moving smoothly and glue the pads to them with disc brake quiet.
Sometimes using silicone brake grease on the backs of the pads attracts dirt and can actually make them squeal more.