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December 1998

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From:
"Fujikura Ltd." <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Thu, 10 Dec 1998 11:21:18 +0900
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text/plain (111 lines)
Forgive me just to express my opinion, it may be of no use in technical
point of view, I would like to introduce the situation concerning UL
testing/approval in Japan.

The "rally" for the subject of UL testing/approval caught my interest
and I was impressed with your very clear comment and am agree with it. I
also remember a part of the comment by Mr. Ed Cosper in which he stated
that the OEMs should pay close attention.

Some OEMs often require all 94-V0 combination of materials for us PWB
manufactures. I think it is one reason we tend to regard "lower flame
level" as "everything is inferior" one. For OEMs, it may be easiest way
to request all 94-V0 materials for each parts to apply for their final
set approval for UL, but I guess it sometimes cause waste of cost
because we PWB manufactures have to select the materials from limited
list intended for 94-V0 even though it cost much.

I understand the requirement of UL is mainly focused on the final set or
products of OEMs and UL recommend appropriate, not always high end,
material for every portion of these products. In our PWB design
viewpoint, we would like to propose the best, or at least better,
material combination that can realize best function and safety
properties at once in lowest cost. I am wondering how the US industry is
facing for this subject.

Thank you for your time for my opinion and I would be very much
appreciated if I could know any input from US industry's viewpoint. I am
here in Tokyo and have no chance to visit US company(who is in the same
business) in order to exchange my idea. But except by TechNet!

Toru Koizumi
Fujikura Ltd.
[log in to unmask]


>Ed,
>
>UL approvals of materials is different than UL approval given to
fabricators.
>The materials usually undergo seperate material testing. The
fabricators
>qualification is after processing of several materials together. An
example
>would be a particular soldermask on a laminate material. The type
soldermask,
>it's thickness, the type laminate material and it's thickness will have
an
>affect on the final flamability rating given to a fabricator.
>
>It is not unusual for a different flame rating to be given for the
combination
>than that given to the individual material. A case in point would be
the use
>of polyimide laminate and soldermask. Many thin polyimide materials do
not
>carry a 94-V0 rating. Especially once a soldermask is applied to it.
But given
>the correct combination of soldermask and polyimide thickness, it is
possible
>to receive a 94-V0 rating.
>
>I don't believe that the fabricator actually "fails" to receive a
rating, but
>would receive a lower rating than he was seeking to achieve. Most
fabricators
>will submit maerial combinations so as to receive several ratings for a
given
>set of tests. As another example. They may submit samples of different
>laminate thicknesses with a specific soldermask apllied to it. The
result
>would be a 94-HB on the thinner materials and a 94-V0 on the thicker
>materials.
>
>Regards,
>
>Gary Ferrari
>Executive Director
>IPC Designers Council
>
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----
Fujikura Ltd.  [log in to unmask]

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