Using MSL3 components in hobby projects

I understand the importance of baking moisture-sensitive parts before using them in a commercial application where even 1% failure rate is unacceptable. But how sensitive are these parts really? If I'm just building hobby projects where the biggest risk is that I might have to desolder a damaged part and replace it with a new one, how much does moisture sensitivity really matter? Is it enough to just keep the parts in a sealed bag with a desiccant and hope for the best when I put them on with hot air or with drag soldering?

In other words, on a scale from 1 to 10, where 1 is "don't worry about it" and 10 is "guaranteed failure", how bad is it to throw caution to the wind and just mount my older MSL3 parts even if they haven't been baked?

Well I've designed 100s of commercial and industrial devices over the years and never heard of MSL3 so maybe that answers your question.

OTOH maybe I should have heard of it :)

Moisture Sensitivity Level 3. Meaning (according to the standard) that the part must be mounted within 1 week of being taken out of its sealed bag, and is only good for 1 year inside the sealed bag. Otherwise it requires a baking process to drive out any accumulated moisture. This is to prevent internal damage when the moisture expands during soldering. It applies mostly to high density chips like 32-bit ARM. Not so much for 8-bit.

Popcorn. I've only seen one part have issues, don't recall much about it (something like an SMPS or POL chip) but I do recall the package actually popped in the reflow oven. The top of the chip was exposed afterward, and wire bonds were history.

Why would they be so sensitive?

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).


The cost sutting mostly comes from mass prroduction :)