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March 1999

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Subject:
From:
Anne Ledger <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Thu, 18 Mar 1999 14:55:05 -0500
Content-Type:
text/plain
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text/plain (131 lines)
Steve,

I never really pay a lot of attention to search engine recommendations,
but that will now change. Now I know why all the people defer to your
greatness.  I will be gladly joining in the 2nd "Steve Day" celebration,
Friday March 19th.

Kidding aside, thanks for the help.

Anne Ledger
EMDS, Inc.


> -----Original Message-----
> From: Stephen R. Gregory [SMTP:[log in to unmask]]
> Sent: Thursday, March 18, 1999 1:10 PM
> To:   [log in to unmask]
> Subject:      Re: [TN] Comparative Tracking Index?
>
> In a message dated 3/18/99 7:26:33 AM Pacific Standard Time,
> [log in to unmask]
> writes:
>
> << Good Morning TechNet,
>
>  I have a fabrication drawing with a note with the following note.
>
>  Material:  .062 laminated glass (woven fabric) base, epoxy resin,
> Flame
>  retardent, FR4. copper clad 2 oz./sq ft.  Laminate must be certified
> to
>  have a minimum comparative tracking index of 175.  Microsection
> demonstrating
>  compliance with copper weight, dielectric spacing, line width and use
> of CTI
> 175 or
>  better material shall be shipped with each lot.
>
>  I am at a loss on the CTI 175 stuff.  I have reviewed IPC 4101 and
> don't
>  find a reference.  I have placed a call to our material supplier but
> no
> response yet.  The TechNet
>  seems much faster. Can anyone provide me with a clue?  Thanks in
> advance for
> the help.
>
>  Anne Ledger
>  EMDS, Inc.
>  [log in to unmask] >>
>
> Hi Anne!
>
>      While I'm waiting for a stencil to get here so I can run a job I
> got set-
> up, I used http://www.dogpile.com search engine to see what I could
> find...and
> I like to learn more stuff besides assembly junk too. But here's what
> it found
> for ya':
>
> Materials are separated into four groups according to their CTI
> (Comparative
> Tracking Index) as follows:
>
> Material group I: 600 < CTI
> Material group II: 400 > CTI < 600
> Material group III a: 175 > CTI < 400
> Material group III b: 100 > CTI < 175
>
> The CTI values above refer to values obtained, in accordance with DIN
> IEC
> 112/VDE 0303, part 1, on samples specially made for the purpose and
> tested
> with solution A. Method for determining the comparative and the proof
> tracking
> indices of solid insulating materials under moist conditions.
>
> ...and reading the stuff on different pages it looks like it has
> something to
> do with surface insulation resistance and a materials ability to
> prevent
> arcing and sparking while carrying specified power loads...(I think) I
> looked
> for the test methods that were referenced above, and other test
> standards
> (IEC 1120 and ASTM D3638-93) that I read as referenced to determine a
> materials CTI, to see if I could read and understand what the heck CTI
> is all
> about, but everybody wants money before they'll let you learn
> anything.
>
> However, if you wanna go to http://www.cssinfo.com you'll find the
> ASTM
> D3638-93 standard there, and if you'll give them a credit card number
> and pay
> $21.95, you can download that standard online. It's precisely the
> standard
> test used to detremine Comparative Tracking Indexs with resins.
>
> Hope this helped a bit...
>
> -Steve Gregory-
>
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