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June 2005

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Subject:
From:
Bev Christian <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Bev Christian <[log in to unmask]>
Date:
Wed, 22 Jun 2005 15:45:51 -0400
Content-Type:
text/plain
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text/plain (270 lines)
John,
Would you be willing to post this on Steve's site?
Bev
RIM

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of John Maxwell
Sent: June 22, 2005 3:42 PM
To: [log in to unmask]
Subject: Re: [TN] Moisture sensitivity levels...

Ingemar,
I have a lovely photo of a tantalum cap that burst open during lead free
reflow. Lots of venting of steam also moving adjacent parts from
tantalum
caps that did not rupture. What fun this lead free will be.

John Maxwell

At 12:15 AM 6/22/2005, you wrote:
>Hi Gaby,
>
>we do have 60% too, all mounting area is 50-60% in order to get low ESD
risk.
>And still, most reels have no baking. Tantalum epoxy molded, resistors,
>ceramics,
>SOTs, QFPs etc are exposed to the humidity in the assembly halls. And
they are
>soldered with no problems, as far as I know. Millions of them.
>
>Exceptions: superBGAs and very large QFPs which are MS classed by the
>component
>maker himself. These are stored in nitrogen cabinets or in plastic bags
with
>dessicators. So, MS classed components are handled with care.
>
>You did not tell us what components caused big trouble. Were they MS
classed ?
>
>Inge
>
>-----Original Message-----
>From: Gabriela Bogdan [mailto:[log in to unmask]]
>Sent: den 21 juni 2005 16:40
>To: TechNet E-Mail Forum; Ingemar Hernefjord (KC/EMW)
>Subject: Re: [TN] Moisture sensitivity levels...
>
>
>Inge, try to work in an environment with up to 60% humidity... we are
baking
>and baking again...
>If we miss we are in big trouble.
>Gaby
>----- Original Message -----
>From: "Ingemar Hernefjord (KC/EMW)" <[log in to unmask]>
>To: <[log in to unmask]>
>Sent: Tuesday, June 21, 2005 9:53 AM
>Subject: Re: [TN] Moisture sensitivity levels...
>
>
> > Steve,
> > how come that you jumped high so sudden? Have you used some kind of
> > humidity issue filter
> > all these years...he-he..cheating. There is humidity everywhere.
Mother
> > nature infiltrates
> > water vapour molecules everywhere she can. We learned that there is
> > humidity even on inside
> > of glass feedtrues, water penetrates deeply into kovar packages,
there is
> > water in the solder
> > paste, every single "plastic" has a small amount of water on inside.
Water
> > molecules are
> > universal and unavoidable. We had a period of humidity hysteria,
digged
> > deeply into the
> > mystery of water penetration mechanisms by means of proffessors and
> > doctors, had seminars,
> > and the learned painted scaring scenarios about all bad things that
could
> > occur due to water in
> > the material. We spent a lot of money on residue gas analysis and
made
> > lots of MIL STD
> > tests and so on. The years pass and behold, a miracle: there has
been no
> > catastroph. Some
> > few reports have been noticed, but the equipments spread all over
the
> > globe seem to work,
> > and mounting seems to go on rather free from incidents despite there
is
> > water in every
> > single component. So, I wonder if all anti-humidity countermeasures
are
> > proportional to the
> > very few failures that occur due to water.
> >
> > My thoughts do not necesserarily represent the general opinion here,
I'm
> > just curious about
> > the mystery of water content and others experience. Is humidity a
severe
> > problem today?
> > Can anyone give example?
> >
> > (I don't include water that penetrates into packages from the
surrounding
> > during field use,
> > but just point at built-in humidity in parts before and during
assembly.)
> >
> > Ingemar Hernefjord
> > Ericsson Microwave Systems
> >
> > -----Original Message-----
> > From: TechNet [mailto:[log in to unmask]]On Behalf Of Stephen Gregory
> > Sent: den 20 juni 2005 17:26
> > To: [log in to unmask]
> > Subject: [TN] Moisture sensitivity levels...
> >
> >
> > Good mornin' all!
> >
> > I hope all you Dads out there had a wonderful Fathers Day!
> >
> > As I posted about a week or so ago, we're getting our stockroom
> > personnel to really focus on component moisture sensitivity levels.
> >
> > But now I'm starting to get a little confused about how components
> > are generally classified with their respective MSL ratings.
> >
> > I've always thought that it had to do with component body size and
> > thickness,
> > but now I'm finding out that it doesn't necessarily.
> >
> > My stockroom clerk showed me an IDT SOJ28 that came in sealed with a
MSL 3
> > rating that we now have in our dry box because the package was
opened.
> >
> > We have some Cypress SOJ28's and SOJ24's that are on reels that are
not in
> > original packaging, so I called Cypress and asked what the MSL
rating is
> > for the
> > two part numbers and they are a MSL 1. Cypress gave me a link to the
SRAM
> > Qualification Report that states that.
> >
> > Now my stockroom clerk brought me some Vishay tantalum caps that
have
> > a MSL 2a rating label on them, and they are TNTC's. This is THE
FIRST time
> > I
> > have ever seen a MSL label on a tantalum capacitor.
> >
> > Are these ratings based on qualification reports? Or can one look at
the
> > size and
> > thickness of the part to base how you will handle it?
> >
> > Kind regards,
> >
> > -Steve Gregory-
> > Senior Process Engineer
> > LaBarge Incorporated
> > Tulsa, Oklahoma
> > (918) 459-2285
> > (918) 459-2350 FAX
> > __________________________________________________________________
> > This message may contain information that is privileged and
confidential
> > to
> > LaBarge, Inc.  It is for use only by the individual or entity named
above.
> > If you are not the intended recipient, you may not copy, use or
deliver
> > this message to anyone.  In such event, you should destroy the
message and
> > kindly notify the sender by reply e-mail.
> >
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