Dear Mr. Steve,
Thanks for your comment, it encouraged me very much.
I guess any special "sandwich" could be ordered for UL restaurant to
cook but I am not sure the price and delivery time.
As my experience for PWB has been limited only for Flexible PWBs, I have
not handled 4 layers of board, with mixed materials, like a special ham
slice inside, for UL application. However, it is often the case for us
to handle mixed materials of construction because CCIL is not applicable
for our Flexible PWB field.
Except for typical single or double sided constructions, Flexible PWB
has something similar to so called "build up method" in Japan.
Therefore, I often discuss with UL engineers, "May I use made in Japan
Tomato ketchup in stead of the Heinz, currently listed in our
Menu?"...like that.
Judging by my experience, it will not so difficult to obtain success for
UL with mixed materials 4 layers, but you had better to choose the
material carefully so that you can change mustard and ketchup in the
range of no taste change, without additional testing.
In addition, in order to go ahead your plan for "special sandwich", the
movement of IPC task group with UL offices concerning UL796 and UL746
would be a good chance to exchange or confirm our ideas among related
industry members. They are just now on going. I will try.
Toru Koizumi
>Koizumi-san,
>
>I agree with your comments. I am also interested in alternate
materials.
>
>I have been conducting research into mixed material multilayers.
>
>Most of our low end motherboards are 4 layer. As you know, the material
>between L2 and L3 has no purpose other than to create the overall
>thickness for through hole components, must be capable of good copper
>adhesion and have acceptable dimensional characteristics.
>
>I am currently trying to find out if mixed materials will pass 94-V0
and
>our reliability requirements.
>
>Have you had success in mixed materials boards? As far as I know, there
>is no application in the US.
>
>Regards,
>Steve Joy
>Technology Development Engineer
>Intel Corporation
>
>
>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]
>
>
----
Fujikura Ltd. [log in to unmask]
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