That indicates that some vendors use new materials that should not be used in this type of application, too hydroscopic. It is good that new materials are tried but if those do not work, try something else. Perhaps more R&D should be used.
Ramon
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of John Maxwell
Sent: Thursday, June 23, 2005 3:10 PM
To: [log in to unmask]
Subject: Re: [TN] Moisture sensitivity levels...
Bruce,
This problem was a production nightmare due to increased inspection. The
vendor was replaced and this was the time I found out that tantalum caps
are moisture sensitive and that all tantalum capacitor vendors are not
created equal. This was a photo of the best of the worst with most
exhibiting small body cracks or movement of small 0603 sized components
adjacent to the cathode end. The tantalum slug is closest to the cathode
and isolated from the anode body end by the anode wire. Time frame was mid
2000 when we experienced this interesting phenomena.
John
At 03:46 AM 6/23/2005, you wrote:
>John,
> Interesting picture, and I too am interested in the answers to
>Ingemar's questions. Also, did you record any examples of what you
>describe as "venting of steam also moving adjacent parts"? I would be
>interested in the escape mechanism and potential reliability problems
>associated with those caps also.
>
>Bruce Stilmack
>GDLS-TO Manufacturing Engineer
>(850) 574-4773
>[log in to unmask]
>
>
>
> "Ingemar
> Hernefjord
> (KC/EMW)" To
> <ingemar.hernefjo [log in to unmask]
> [log in to unmask]> cc
> Sent by: TechNet
> <[log in to unmask]> Subject
> Re: [TN] Moisture sensitivity
> levels...
> 06/23/2005 02:30
> AM
>
>
> Please respond to
> TechNet E-Mail
> Forum
> <[log in to unmask]>
> ; Please respond
> to
> "Ingemar
> Hernefjord
> (KC/EMW)"
> <ingemar.hernefjo
> [log in to unmask]>
>
>
>
>
>
>
>John,
>1.How did you know for sure that this was caused by moisture?
>
>2.Furthermore, do you have an idea about what amount of moisture
>is needed for such an explosion?
>
>3. If you had several more tantalums on that board or other boards
>from that lot, why just only this one? Why did not the others explode
>too?
>
>Ingemar
>
>-----Original Message-----
>From: TechNet [mailto:[log in to unmask]]On Behalf Of John Maxwell
>Sent: den 22 juni 2005 21:42
>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
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