Hi Werner
I haven't got a copy of the 6013 document so I cannot
comment on the text you refer to .
As a user of flexibles I would sure appreciate
a guiding kind of table suggesting or defining parameters
for selection between applications like "flex to install"
and "continuos flexible operation".
Another thing that confuses me in the present document
"ipc-fc-250" is the discrepancy between para. 3.8.3:
conductor width reduction of no more than 20 % .
While para. 3.8.4 sends you to table 8 where class 2 product
is allowed to have only 30% remaining width;
for added confusion table 20 defines 20% reduction
as a "major defect".
Can you immagine what a 20 or 30 persent reduction in conductor
does to a controlled impedance line ? not mentioning 50 or 60
persent !
I might be misunderstanding, but clear definitions
will make things simpler and not open to any interpretations.
Thanks,
Mickey
Engelmaier wrote:
> Hi TechNetters,
> We just finished discussing copper foils and the shortcomings observed in
> product.
> Currently, a new IPC document, IPC-6013, Qualification and Performance
> Specification for Flexible Printed Wiring, is being circulated for comments.
> In it, under 3.2.5 Metal Foils, "copper foil should be in accordance with IPC-
> MF-150, which is modified in 3.2.6.2 Copper with "the tensile strength shall
> be no less than 245 MPa and the elongation shall be no less than 12%."
> While the modification is a step in the right direction, it should be part of
> section 3.2.5, not detached from it. Technically, requiring an elongation of
> 12%, rather than the 2 or 3% minimums in MF-150, is also appropriate. However,
> why specify elongation. For comparative and process control purposes,
> elongation is fine, however, it has long been recognized as an inadequate way
> of determining the actual ductility of foils. From a sample geometry of foil
> tensile test samples makes the measurement of ductility by this method
> impossible. Further, the results are highly dependent on testing technique.
> That is why ASTM E 796, "Standard Test Method for Ductility Testing of
> Metallic Foil" and IPC-TM-650, Test Method 2.4.2.1,“Flexural Fatigue and
> Ductility, Foil,” were developed.
> I urge interested TechNetters to ask for the following TECHNICAL CHANGES:
> (1) Ductility as per TM 2.4.2.1 should be specified;
> (2) Combine Sections 3.2.5 and 3.2.6.2;
> (3) Include Table A1 'Applications Guide for Copper Foil' which distinguishes
> between the difference needs for 'Flex-to-Install' and 'Continuous Flexing',
> or something like it.
>
> Werner Engelmaier
> Chairman, IPC Product Reliability Committee
> Past Chairman, IPC-MF-150 Task Group
>
>
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