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From: Joerg on 14 Mar 2010 16:37
D from BC wrote:
> In article <kr1qp5p3ojq9m40ae5gfh6t5kun8ppgc8m(a)4ax.com>,
> quiettechblue(a)yahoo.com says...
>> On Fri, 12 Mar 2010 15:19:46 -0800, D from BC <myrealaddress(a)comic.com> wrote:
>>
>>> In article <fa8a0108-f3dc-45a0-bdfa-04d8601470d5
>>> @o3g2000yqb.googlegroups.com>, whit3rd(a)gmail.com says...
>>>> On Mar 11, 4:27 pm, Joerg <inva...(a)invalid.invalid> wrote:
>>>>> D from BC wrote:
>>>>>> I'm trying to find the breakdown V for
>>>>>> 0.0028 inches of PTFE (teflon) and 0.004 inches (~100um) of Kapton.
>>>> Textbook value for PTFE aka TFE aka Teflon is 480 volts per milli-
>>>> inch,
>>>> and for polyimide/Kapton is 560 volts per milli-inch.
>>>>
>>>> That assumes pure material, clean surfaces, and no conduction
>>>> enhancement from ambient light...
>>>> This data, from _The_Practicing_Scientist's_Handbook_, Moses, Alfred
>>>> J.,
>>>> 1978 edition...
>>> Huh.. That's wayyyy different than what's on the link that Joerg
>>> provided.
>>> http://zodiaq.fr/Kapton/en_US/assets/downloads/pdf/CR_H-54506-1.pdf
>>>
>>> Table 2
>>> Kapton Type 150 FCR Polyimide film 1.5 mil : 4400V/mil
>>>
>>> Table 1
>>> Kapton Type 100 CR Polyimide Film 1mil: 7400V/mil
>>>
>>> I supppose it depends on the type of polyimide.
>>> Perhaps the withstand test is differant.
>>>
>>> According to (blows dust off book :O === ***)
>>> Reference Data for Engineers 1993
>>> Polyimide: 570 V/mil << Not far from your book.
>>>
>>> However..
>>> On ebay item 180431395463 Kapton film
>>> 1mil Kapton + 1.4 mil silicone adhesive has breakdown at 6000V !
>>>
>>> Ebay item 330275429870
>>> 1mil Kapton + 2mil mil silicone adhesive has breakdown at 7500V!
>>>
>>> Either silicone adhesive has an impressive breakdown or the Kapton
>>> breakdown is higher than the polyimide spec in text books.
>> DO NOT confuse nor conflate breakdown ratings with operational ratings.
>>
>
> That's what happened. I went for the short term spec (V breakdown). When
> I should be looking at the long term spec (hours to insulator
> deterioration by corona).
>
> The text books list operational.
>

If you are building something that needs to pass muster at an agency
(pretty much anything does) there are only two things that count:

a. The standard

b. A formal statement by the manufacturer and this has to be in writing.
A book doesn't count. BTDT, many many times.

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.
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