One thing you should definitely verify is that the "non-standard" issue is
related solely to inventory issues.  There are some shops that don't run
unbalanced copper weights.  It's not that it's rocket science but they just
haven't invested the effort to doing so.  If this is the case and they don't
really have process for doing this, you're looking at a completely different
issue.  If you've got a shop that is doing this for the first time, I'd ask
for some data verifying that they are doing it correctly.

From an inventory perspective, this combination of copper clad should be
readily available.  It's not used as commonly as some of the other clad
combinations which can complicate availability.  Let's face it, there are so
many different materials available in so many thicknesses, that no shop can
afford to keep inventory of every possible combination of clad materials.
But if you use only a few different cores with this combination of clad
weights, you should be able to work with the fabricator to stock adequate
levels for your needs.  It sounds there's a disconnect between what you and
your fabricator consider "standard".  Perhaps your Purchasing department can
help you get calibrated.



> ----------
> From:         Takach, Lou J[SMTP:[log in to unmask]]
> Reply To:     TechNet E-Mail Forum.;Takach, Lou J
> Sent:         Monday, March 18, 2002 4:11 AM
> To:   [log in to unmask]
> Subject:      [TN] Non-Standard material
>
> Good Morning Technetters...
>
> I need your input / advice. Our manufacturing facility has recently
> (within
> a year or so...) switched to a new PCB fabricator. I'm now starting to get
> complaints from manufacturing that our fabricator is having trouble
> obtaining the 'non-standard' material that we are specifying.  First of
> all,
> I don't believe that I'm specifying non-standard material, this is where I
> need your input. Most of our boards are multi-layer, usually 4 to 6 layers
> and we use FR4. We typically specify 2-oz copper on the internal power and
> ground layers and sometimes 1-oz copper for the outer signal layers. Is
> this
> non-standard? The fabricator says that they typically don't stock 1 over 2
> copper. Maybe I'm missing something but I thought that the stackup could
> be
> made of individual copper sheets of various copper weights as long as the
> layer sequence was balanced.
>
> All comments welcome...
>
> Lou
>
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