Isaac96:
Why would they be so sensitive?
It depends on environment, I live in the High Desert, right now 2 hrs after dark, the temp is 64 degrees fahrenheit with a relative humidity of 23% and a dew point of 31F ( below freezing, so the dew would have to fall as snow!), at 5pm today it was 95 degrees with humidity below 10%. (I can almost 'bakeout' smt by leaving them on my front poarch!)
Moisture sensitivity levels are written for the sea level world. I have never had problems, (25 years).
The plastics that encapsulate the die are the cheapest they can get away with. Back in the day we used ceramic IC's that were water proof, vacuum sealed, with thick gold plating. And they were not Cheap!
A single cpld could cost you a weeks pay. Now I can buy a 32bit cpu assembly for $2. The cost cutting has to come from somewhere.
The new IC's are designed to hold the die, not protect it. If the resin has channels and voids, no big deal. The die has been passiviated with a thick oxide coating. The MSL is because H2O expands like crazy when heated, the 'oven baking requirement just allow the moisture to flow back out the channels it came in without generating enough force to explode the package.
I use surplus Army ammo cans to store my smd's, both for static and moisture. I worry more about static, with my dry air I can generate a 2" spark that hurts when I touch the door knob. (Febreze diluted 100:1 solves the carpet static).
Chuck.