Jim.
We have used these for many years, and I have not heard about 'severe'
moisture problems. We have used both reels and discrete ones. As we must
be prepared to take care of reparents (up to 20 years), we have reels in
stock for a long time, probably years. They are not stored in
dessicants or sealed bags, but in ordinary +25/RH30% atmosphere. I
agree, that all plastic parts should be suspects, but in practice very
few incidents have occurred here. I have eyed some references when I was
involved in a presumed humidity absorption problem. Noone of those
reports had any humidity rejects. Maxim is an example. I'll send that
humidity TSSOP test report to you offline.
Inge
PS. Tantalum caps with plastic bodies have exploded here, because of
absorbed humidity, but it's not comparable with a TSSOP, of course.
Inge
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D.
Sent: den 11 oktober 2006 14:53
To: [log in to unmask]
Subject: Re: [TN] Are TSSOP-8 packages moisture sensitive
Jim-
Wayne is correct. I had overlooked the fact they are in tape and reel.
You may be better off trying to determine if the package is still
sealed, with a moisture indicator card inside of the drypack. If the MIC
is still blue, the parts are probably OK to use. In that case I would
simply replace the dessicant with fresh dessicant and reseal the bag,
and put them in a McDry dessicator until ready to use.
All per J-STD-033.......
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Wayne Thayer
Sent: Wednesday, October 11, 2006 7:34 AM
To: [log in to unmask]
Subject: Re: [TN] Are TSSOP-8 packages moisture sensitive
Jim-
The depressing aspect of your problem is the word "reel". There is no
way to effectively bake them out while still on the reel without taking
literally months. There are reel service houses who will de-reel, bake,
and re-reel for you. Last I checked that is about $100 for each reel.
Also, bakeout may reduce solderability due to oxide growth unless its
done inertly.
The old test to see if a package needed to be baked out was to grab a
handful of them and toss them into a solder pot (while wearing
appropriate personal protective equipment, of course!). This test was
called the "popcorn" test, and was appropriate for wave soldered SMT.
If some of the packages "popped", then they need bakeout. Pretty crude,
but it was actually used for awhile. More scientifically, you could try
and find a "maximum moisture level" for the package and then measure the
moisture level by baking some parts and compare weights before and
after. The accuracy of your scale will determine how many parts you
will need to bake to get a sufficiently accurate wt% moisture.
Wayne Thayer
>>> [log in to unmask] 10/11/2006 8:21 am >>>
Jim,
Per J-STD-033 and J-STD-020, the package of components must be clearly
marked with the component's MSD level, and should be handled as such.
Tell the chip manufacturer to get with the program.
And bake the parts.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Tempea, Ioan
Sent: Wednesday, October 11, 2006 7:17 AM
To: [log in to unmask]
Subject: Re: [TN] Are TSSOP-8 packages moisture sensitive
Jim,
all plastic packages are MSDs. You have to contact the manufacturer to
have the specifics, or, if you are lucky you are going to see the MSD
level on the bags when you get the part.
Good luck,
Ioan
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of West, Jim
Sent: Tuesday, October 10, 2006 4:24 PM
To: [log in to unmask]
Subject: [TN] Are TSSOP-8 packages moisture sensitive
Are TSSOP-8 packages susceptible to moisture? We have a chip
manufacture offering a reel of a TSSOP component that has been on their
shelf since late '04'. The component is a N-Channel MOSFET. By the
time we receive them, it will be late this year, should I bake them when
we get ready to use to be safe?
Thanks,
Jim West
Engineering Manager
Nexergy Inc.
www.nexergy.com
tel: (614) 351-6216
fax: (614) 324-1979
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