I have soldered through-hole and SMT before but this is the first time I have to do SMT (QFN) package which has no legs. I tried the traditional approach, Flux, solder, then heating the component. But here the pads are underneath that it's been a nightmare to reach em to apply heat.
I worked with somebody back in the day who soldered in a different way. He applied something on the pads(very thick paste), I'm guessing Solder/flux paste. It managed to keep the components right where there are. Then he put the board in a microwave and ran it for a few minutes. Then the components were soldered perfectly. No issues what so ever.
My question is, what's that paste? Is my guess right? What exactly is it called so that I can buy one?
If I'm wrong, then how does one normally solder these components?
My component is a micro msp430fr2433.