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June 2013

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From:
"Whittaker, Dewey (EHCOE)" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Whittaker, Dewey (EHCOE)
Date:
Tue, 18 Jun 2013 21:29:28 +0000
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Schrodinger's?
Dewey

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Inge Hernefjord
Sent: Tuesday, June 18, 2013 2:12 PM
To: [log in to unmask]
Subject: Re: [TN] APEX Papers on Conformal coat and tin whiskers

I am glad the whiskers in my nose isn't Tin. Imagine they grow and grow, and one day you look like a cat.

Inge


On 18 June 2013 12:00, Steven Creswick <[log in to unmask]> wrote:

> Dewey
>
> Is this an e-mail link to a group or something?
>
> Steve C
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Whittaker, Dewey
> (EHCOE)
> Sent: Tuesday, June 18, 2013 12:57 PM
> To: [log in to unmask]
> Subject: Re: [TN] APEX Papers on Conformal coat and tin whiskers
>
> Also try [log in to unmask]
> Dewey
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Bob Landman
> Sent: Tuesday, June 18, 2013 9:50 AM
> To: [log in to unmask]
> Subject: Re: [TN] APEX Papers on Conformal coat and tin whiskers
>
> John Barnes is the person collecting the bibliography (> 20,000 
> citations)
>
> *  Bibliography for Tin Whiskers, Zinc Whiskers, Cadmium Whiskers, and
>   Other Conductive Metal Whiskers
>     http://www.dbicorporation.com/whiskbib.htm
>
> Bob Landman
>
> On Jun 18, 2013, at 5:52 AM, Steven Creswick 
> <[log in to unmask]>
> wrote:
>
> > Inge,
> >
> > Sorry, but was not me.  I can imagine there being a great deal of 
> > non-published work out there, however.
> >
> > Smooth skies!
> >
> > Steve C
> >
> > -----Original Message-----
> > From: TechNet [mailto:[log in to unmask]] On Behalf Of Inge Hernefjord
> > Sent: Tuesday, June 18, 2013 1:27 AM
> > To: [log in to unmask]
> > Subject: Re: [TN] APEX Papers on Conformal coat and tin whiskers
> >
> > FYI
> >
> > Someone (Trikeman?) told me that about 10,000 papers exist about
> whiskers.
> > Of course most of them are echoes.
> >
> > Inge
> >
> >
> > On 12 June 2013 07:26, greg <[log in to unmask]> wrote:
> >
> >> There have been several papers published at APEX on the topic. But 
> >> whether they address the specific issues raised today I leave to 
> >> wiser heads than mine.
> >>
> >> APEX 2007:
> >>
> >> Effect of Conformal Coating on Tin Whisker Growth, Vijay Kumar and 
> >> Linda Woody, Lockheed Martin
> >>
> >> Parylene as a Suppressant for Tin Whiskers Growth on Printed 
> >> Circuit Boards, Rakesh Kumar Specialty Coating Systems
> >>
> >> Whisker Penetration into Conformal Coating, Stephen McKeown, Joseph 
> >> Kane, Dr. Stephan Meschter BAE Systems, Johnson City, NY
> >>
> >>
> >> APEX 2008:
> >>
> >> Effects of Tin Mitigation Processes on Whisker Growth and Solder 
> >> Joint Reliability for Chip and Small-Outline Package Components, 
> >> Tom Lesniewski and Tom Higley, Northrop Grumman Network 
> >> Communications, San Diego, CA 92128
> >>
> >> APEX 2010:
> >>
> >> Conformal Coatings for Tin Whisker Risk Management, William Fox and 
> >> Linda Woody Lockheed Martin Missiles and Fire Control, Ocala, 
> >> Florida
> >>
> >>
> >> And Chris Hunt did publish also but the APEX papers of his do not 
> >> talk about conformal coating. (He may have published somewhere else 
> >> on whiskers/coatings. Dave who published on tin coated braided wire 
> >> may want to weigh in after he returns.)
> >>
> >> Having done the file search on the above whiskers/coatings APEX 
> >> papers and read their summaries the answer to "Does it help?" seems 
> >> (to me) to be somewhere between "yes/no/maybe/it depends." (i.e. 
> >> it's "above my pay
> >> grade.")
> >>
> >> Greg Munie
> >> IPC Director of Design Programs
> >>
> >>
> >>> -------Original Message-------
> >>> From: Mike Fenner <[log in to unmask]>
> >>> To: [log in to unmask]
> >>> Subject: Re: [TN] minimum thickness of Type UR Conformal coat and 
> >>> tin
> >> whiskers
> >>> Sent: 12 Jun '13 09:07
> >>>
> >>> Richard, slightly tongue in cheek I ask: How does soldering with
> >> tin/lead
> >>> prevent tin finish on PCB whiskering?
> >>>
> >>> Phil I recall Chris Hunt of NPL in UK did some work on this. You 
> >>> can probably download a copy of paper from their WWW.
> >>>
> >>> Best Wishes
> >>>
> >>>
> >>>
> >>> Mike
> >>>
> >>>
> >>>
> >>> -----Original Message-----
> >>> From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D.
> >>> Sent: Wednesday, June 12, 2013 2:22 PM
> >>> To: [log in to unmask]
> >>> Subject: Re: [TN] minimum thickness of Type UR Conformal coat and 
> >>> tin  whiskers
> >>>
> >>> Not only can the whiskers grow through the conformal coating, they 
> >>> can
> >> grow
> >>> under it like weeds in a stream. NASA has some good pictures of 
> >>> this on  their website.
> >>> The best tin whisker mitigation scheme is called tin/lead solder.
> >>>
> >>> -----Original Message-----
> >>> From: TechNet [mailto:[log in to unmask]] On Behalf Of Douglas Pauls
> >>> Sent: Wednesday, June 12, 2013 8:10 AM
> >>> To: [log in to unmask]
> >>> Subject: Re: [TN] minimum thickness of Type UR Conformal coat and 
> >>> tin  whiskers
> >>>
> >>> Phil,
> >>> While this is an answer I "should" know, I don't.  Dave Hillman
> >> regularly
> >>> attends and presents at the CALCE yearly conference on whiskers 
> >>> and so
> >> he
> >>> keeps up on all of that.  At present, my esteemed colleague is 
> >>> bumping
> >> his
> >>> head on rocks, kayaking upside down, on some white water in North
> >> Carolina.
> >>> He should be back in the office on Monday and will no doubt answer
> > then.
> >>>
> >>> From our discussions, the general rule is still "no conformal 
> >>> coating  prevents whiskers".  A thicker coating may cause the 
> >>> whisker to expend
> >> more
> >>> energy punching through and yet more energy to punch through an 
> >>> adjacent  coating on a lead (usually resulting in buckling), but I 
> >>> have yet to
> >> hear
> >>> about some magic thickness of any kind of coating that completely
> >> mitigates
> >>> whiskers.  But I could be wrong.
> >>>
> >>> Dave?
> >>>
> >>> Doug Pauls
> >>>
> >>>
> >>>
> >>> From:   Phil Bavaro <[log in to unmask]>
> >>> To:     <[log in to unmask]>
> >>> Date:   06/11/2013 02:26 PM
> >>> Subject:        [TN] minimum thickness of Type UR Conformal coat and
> > tin
> >>> whiskers
> >>> Sent by:        TechNet <[log in to unmask]>
> >>>
> >>>
> >>>
> >>> Doug et al,
> >>>
> >>> Is there a disagreement in the industry as to what minimum 
> >>> thickness of  urethane is required in order to mitigate tin 
> >>> whisker
> > concerns?
> >>>
> >>> I am hearing that the .003+/-.002" does not provide enough of a minimum
> >>> thickness and that the number is as high as .004".   I can understand
> >>> wanting the minimum being raised to .002" but higher than that 
> >>> would
> >> seem to
> >>> make the process much more difficult to control.
> >>>
> >>> I have a potential customer asking if we measure the thickness on 
> >>> the  individual component leads which is another can of worms it 
> >>> seems.  We  always used flat samples to document our thicknesses.
> >>>
> >>> I did not get to attend this years APEX so I might have missed the
> >> latest
> >>> data.
> >>> ________________________________
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> >> recipient, any
> >>> disclosure, use or distribution of its content is prohibited.
> >>> Please
> >> notify
> >>> the sender by reply e-mail and immediately delete this message and 
> >>> any  attachments.
> >>>
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