Hello iam looking at buying some IC's in somewhat big quantity,They're wireless RF IC's in QFN package.What should i be concerned with storing them i've read some might have a "mount by date" where aslong as it is solder to a board before x amount of days the IC is good.The company that makes them arent a huge manufacturer and i want to make sure before i buy that many i dont have to mount them right when i get them,or need a special temperature room,etc.Any help is appreciated thanks

 

Hello,

Have a look in the datasheet for the IC's.
Those will give operating and storage temperatures.
Here is an example for the AD524:



Bertus

 

Ah i will have to look at there sheet from them,I just have gotten buck converters from mouser in a ESD bag saying its shelf life is 7 days in the sealed bag,or onced open it has be mounted before 72hours.But now that i went back to the data sheet and looked at the bottom of the buck converter it does show a MSL Peak Temp Parameter Level-3-245C-168 HR which makes sense now.I guess i will have to get the full datasheet or spec sheet from them.

 

The reason for the "mount by date" is from concerns about the pins oxidizing and becoming difficult to solder.
If that happens, usually a small amount of rosin flux applied to the pins will make them easy to solder.
I see no other concerns if you store them in a sealed ESD bag or container at room temperature.

 

If they are expensive, store in sealed bags with dessicant to reduce humidity

If you live a humid area, the leads can become tarnished to the point where they are unusable after 6 months of storage.

 

The MSL level is how sensitive the pins are to oxidation. There are procedures (baking) to resurect components that exceed the storage limits,