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[on:]

So I just got some samples from TI. 
The two items in question are:
UA7805CKTTR voltage regulator and INA139NA/250 current shunt chip

They came in the shiny static sensitive bags, what I was not expecting is the "CAUTION Moisture Sensitive Device" warning sticker on the pack.  The warning label also states that the part must be mounted within 1hr of opening for re-flow soldering. 

Whats up with this?
I was not expecting ICs to have a shelf life in this way.

[Reply #1 on:]

I recently received some SMD LEDs with similar warnings. They came packed with dessicant and an indicator card. That's a new one on me, too. This label indicates the parts can be baked if the specified conditions are not met.

[Reply #2 on:]

This is because when you are flow soldering the chips in an oven moisture ingress in the chip can cause physical damage as it expands into steam. To stop that you keep the chip in a low humidity environment before using or you bake the chip for 24 hours at high temperature before using.
Either way unless you are planning to use a reflow oven it is nothing to worry about.

[Reply #3 on:]

Isn't someone going to yell at the poor gentleman for ordering samples and "ruining it for everyone else"?  

P.S.  experience says TI/National will send you a 11 bit 200MSPS ADC no questions asked, a $50 part at Digikey.

[Reply #4 on:]

Thanks, Mike. OTOH, other (most?) SMT chips and devices carry no such warning. I figured the construction of the LEDs differed from other semiconductors somewhat (just from appearance) but the OP's voltage regulators still puzzle me. I've recently worked with an SMT boost regulator and an RTC chip that carried no humidity warnings.

[Reply #5 on:]

I just got a d2pak 7805 and it had that warning, also some silic packet and a paper humidy sensor
it said I had to bake it within 128 hours if the humidy was above a certain percent

[Reply #6 on:]

OTOH, other (most?) SMT chips and devices carry no such warning.

Yes they all do and always have. It is just that they have started to include this when you buy stuff in small quantities. Especially when you are getting samples from a manufacturer rather than a distributor.

[Reply #7 on:]

OTOH, other (most?) SMT chips and devices carry no such warning.

Yes they all do and always have. It is just that they have started to include this when you buy stuff in small quantities. Especially when you are getting samples from a manufacturer rather than a distributor.

Is that because more engineers and hobbiests are using reflow ovens to assemble prototypes rather than hand-soldering them these days or what?  Do you know why this is a danger with reflow ovens and not for hand-solder methods?

[Reply #8 on:]

Because the chips don't get as hot and don't stay hot for so long when you hand solder.

[Reply #9 on:]

All components in epoxy housing are moisture sensitive. If you read the datasheet it usually say this, or if it doesn't usually the manufactorer have a "general" datasheet for that kind of package with dimensions etc.

It's just because they have begun to enclose the warnings, which they didn't do before. Nothing has changed.