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You all,
I need some understanding and maybe some cross references to CTI Rating.
What I think I know is what follows:
1) Under IEC 950 document at section 2.9.3 "Creepage distances" item 3
relates that the CTI (comparative tracking index) rating is a value
obtained with method A of IEC 112 document; I do not have this one.
2) If one knows the CTI then a pc board may attain a specific Material
Group under Table 6 (Minimum creepage distances), contained in the same
section 2.9.3 as stated above, along with knowing the Pollution degree.
3) Also, the Material group and the Working voltage will allow a minimum
creepage distance.
4) There is a CTI column on some UL cards from some of the PC Board vendors
but they do not have any data, just a dashed line.
What I want to know is:
1) How do I find out what the CTI rating is for a PC Board from a PC Board
vendor that I would use.
2) Is the solder mask the only consideration or does the board material
come in to play for the final CTI rating.
3) What does a PC Board vendor have to do to get a CTI rating.
4) What information do I have to specify on my PC Board Fabrication
Document?
5) What specific publications and other documents might explain what CTI
exactly is?
6) Is there a cross reference document to the CTI rating, like maybe
IPC-840-C or information from the Solder Mask vendors?
7) Any and all related information would be appreciated. Please e-mail to
me along with addressing technet for all others.
Much Thanks,
Greg Kaskey
Senior PCB Designer
Checkmate Electronics, Inc.
770.594.6000 x228
[log in to unmask]
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