At 12:00 PM 10/30/2013, Whittaker, Dewey (EHCOE) wrote:
>What, you think my career is winding down and I'm just left with my 
>core competency?

using inductive reasoning can be useful while careers are in flux.

>Dewey
>
>-----Original Message-----
>From: TechNet [mailto:[log in to unmask]] On Behalf Of Phil Bavaro
>Sent: Wednesday, October 30, 2013 11:51 AM
>To: [log in to unmask]
>Subject: Re: [TN] SMT transformer failures
>
>I have a lot of experience (unfortunately) with SMT transformers 
>falling apart but it is not usually the windings themselves but 
>rather the core bonding adhesive separating.  In my experience, the 
>insulation on the windings is pretty rugged.  It takes a lot to 
>degrade that material so I would suspect exposure to something nasty 
>(solvent wise) or else as received from the manufacturer of the 
>wires.  Fuzzy could be anything......go ahead Dewey......!!
>
>-----Original Message-----
>From: TechNet [mailto:[log in to unmask]] On Behalf Of Reuven Rokah
>Sent: Wednesday, October 30, 2013 11:09 AM
>To: [log in to unmask]
>Subject: Re: [TN] SMT transformer failures
>
>What kind of failure mode?
>
>
>On Wed, Oct 30, 2013 at 7:04 PM, Ed Popielarski
><[log in to unmask]>wrote:
>
> > Good Morning Esteemed Colleagues,
> >
> > We have recently been experiencing increasing failure rates of an SMT
> > (5.2 X 5.2 X 1.2 mm) transformer. The first build in September showed
> > about 6% fallout. Subsequent builds from the same reel have increased
> > to 25% most recently. These components have been stored in a normal
> > ambient environment. I have verified and re-verified reflow conditions
> > are well within manufacturer's specifications (confirmed by the 
> manufacturer).
> >
> > When this problem was first identified, I "dissected" one of the
> > failing devices and found the wire pair (primary and secondary) in
> > good condition on the outer windings, but as I continued to unwind
> > down to about 1/3 deep, the insulation began to stick both side by
> > side and to subsequent layers which would "fuzz" as it was pulled 
> apart with exposed copper implied.
> >
> > I am beginning to suspect "cold flow", a problem that was prevalent in
> > the days of wire wrapped backplanes.
> >
> > Has anyone experienced a similar condition? The manufacturer has been
> > "working on it" since mid-September and has yet to provide any root
> > cause and/or solution.
> >
> > Any insight would be appreciated.
> >
> >
> > Ed Popielarski
> > Engineering Manager
> >
> > [Description: FullLogo]
> >                                970 NE 21st Ct.
> >                               Oak Harbor, Wa. 98277
> >
> >                               Ph: 360-675-1322
> >                               Fx: 206-624-0965
> >                               Cl: 949-581-6601
> >
> >
> > https://maps.google.com/maps/myplaces?hl=en&ll=48.315753,-122.643578&s
> > pn=0.011188,0.033023&ctz=420&t=m&z=16&iwloc=A
> >
> >
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>
>--
>
>Best Regards,
>
>*Reuven Rokah*
>
>Mobile: 972-52-6012018
>Tel:        972-3-9360688
>Fax:          076-5100674
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