Baking parts sometimes necessary?

[John]

I ordered a couple of samples from TI and was surprised to find one
bag of the parts in a moisture-barrier bag with a "Bake prior to vapor
or IR soldering to reduce the chances of damage" warning label. The
other, seemingly similar, part came in a standard anti-static bag.

REF5040AID - in vapor barrier antistatic bag
REF5020AID - in standard antistatic bag

These parts, IMHO, are pretty darn similar considering that only the
voltage is different. Is there any special reason one was tagged as
needing baking and the other wasn't?

I checked the TI web site for moisture-sensitivity info and the
"rating" for both parts was the same:

REF5020AID MSL Level-2-260C-1 YEAR
REF5040AID MSL Level-2-260C-1 YEAR

From the TI site: "MSL (Moisture Sensitivity Level): is a JEDEC
industry standard classification that defines the length of time
products can be safely exposed to the ambient environment prior to
high-temperature reflow soldering."

It appears that they are both as sensitive (or not) to moisture, so
I'm a bit confused as to why the REF4040AID part was vapor-barrier
bagged. Not really important?

Thanks for any help you can give me,
John

 

[John]

Just to be clear, there's no way I'm baking any components before
using them.

I was just wondering why similar components might be marked different
ways. I'll order different parts if I find that any really require
baking just for playing-around and low-volume device manufacture....no
mil or high-rel applications here.

John

 

[Tim Wescott]

On Fri, 04 Jan 2008 19:43:41 -0500, John wrote:

I ordered a couple of samples from TI and was surprised to find one bag
of the parts in a moisture-barrier bag with a "Bake prior to vapor or IR
soldering to reduce the chances of damage" warning label. The other,
seemingly similar, part came in a standard anti-static bag.

REF5040AID - in vapor barrier antistatic bag REF5020AID - in standard
antistatic bag

These parts, IMHO, are pretty darn similar considering that only the
voltage is different. Is there any special reason one was tagged as
needing baking and the other wasn't?

I checked the TI web site for moisture-sensitivity info and the "rating"
for both parts was the same:

REF5020AID MSL Level-2-260C-1 YEAR
REF5040AID MSL Level-2-260C-1 YEAR

From the TI site: "MSL (Moisture Sensitivity Level): is a JEDEC industry
standard classification that defines the length of time products can be
safely exposed to the ambient environment prior to high-temperature
reflow soldering."

It appears that they are both as sensitive (or not) to moisture, so I'm
a bit confused as to why the REF4040AID part was vapor-barrier bagged.
Not really important?

Thanks for any help you can give me,
John

At sample quantities it's quite possible that someone was careless about
putting the tag on the bag. If you're not reflowing them they probably
don't need to be baked -- if you _are_ going to reflow them, think of
popcorn.

--
Tim Wescott
Control systems and communications consulting
http://www.wescottdesign.com

Need to learn how to apply control theory in your embedded system?
"Applied Control Theory for Embedded Systems" by Tim Wescott
Elsevier/Newnes, http://www.wescottdesign.com/actfes/actfes.html

 

[John]

At sample quantities it's quite possible that someone was careless about
putting the tag on the bag. If you're not reflowing them they probably
don't need to be baked -- if you _are_ going to reflow them, think of
popcorn.

Yea, you're probably right.
I do like popcorn though.
John