Hi Howard,

Ok the label is real, it is not a left over April fools day joke.

I take it the parts are surface mount ?

With surface mount components when soldering the following happens:
# The temperature is high for a fair period of time
# The temperature is relatively even over the entire chip
# The temperature level is raised fairly rapidly

Any moisture that has seeped into the bond between the top and bottom half
of the component will rapidly expand (it is steam now)as the exit (around
the leads / legs) is not big, the pressure can cause the component to loose
its top, and or break the wire bonds off either the die or the legs (or
both).

This problem only occurs in soldering techniques where individual legs are
not heated i.e. where the device / legs are heated as a whole. If a device
is left in the open and mass heating techniques are to be used, then the
device needs to be baked according to the data from the manufacturer to
slowly dispel any moisture.

Hope this helps,

Regards,

Kat.

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----- Original Message -----
From: "Howard McGinnis" <hmcginni@DIGITAL.NET>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Tuesday, September 25, 2001 10:15 PM
Subject: [OT] Moisture Absorbing Parts?


> I just received samples of Burr-Brown's ISO-124 low cost isolation
> amplifier from TI and found an unusual label attached to the normal static
bag:
>
> NOTICE!! PARTS ARE SUBJECT TO MOISTURE ABSORBTION. TAKE CARE TO PREVENT
> DAMAGE WHEN VAPOR OR IR SOLDERING. BAKE PRIOR TO SOLDERING TO REDUCE THE
> CHANCE OF DAMAGE.
>
> These are somewhat normal looking DIP packages, other than the fact that
> they don't have a full complement of legs.
>
> What's the deal? Is it the manufacturing process?
>
> Howard
>
> --
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>

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