Is it likely that the insulation is reacting with itself, either
incorrect cure or a missing hardener / component due to imposed
environmental restrictions. I remember working on tape recorders that
the tires would just dissolve over time and leave a black sticky mess.
pat
On Thu, Oct 31, 2013 at 7:07 AM, Ed Popielarski wrote:
> NEMA MW82-C Class 180 C
>
> Ed Popielarski
> Engineering Manager
>
>
> 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&spn=0.011188,0.033023&ctz=420&t=m&z=16&iwloc=A
>
>
> -----Original Message-----
> From: Don Vischulis [mailto:[log in to unmask]] Sent: Thursday,
> October 31, 2013 4:10 AM
> To: TechNet E-Mail Forum; Ed Popielarski
> Subject: Re: [TN] SMT transformer failures
>
> Any idea what type insulation is on the magnet wire or the NEMA
> designation of the magnet wire?
>
> Don Vischulis
>
> Sent from my iPad
>
>> On Oct 30, 2013, at 12:04 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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