[SI-LIST] Re: PCB thin dielectrics
- From: Istvan Novak <istvan.novak@xxxxxxx>
- To: "Bowden, Ivor" <ibowden@xxxxxxxxxxxxxxxxx>
- Date: Fri, 18 Dec 2009 20:24:33 -0500
Hi Ivor,
To answer your base question, yes, thin laminates offer a practical way
to increase PCB layer count if you want to keep overall thickness fixed.
As others pointed out, you will need to look at all important aspects:
among others cost, manufacturing concerns, availability and other
practical limitations, such as in larger rigid boards you probably will
need to limit the thin laminates to power-ground sandwiches.
If a 2-mil laminate thickness buys you enough vertical room, the
glass-reinforced ZBC2000 laminate has been around for many years. My
first experience with the ZBC2000 laminate was 16 years ago when we used
it in a small data-acquisition card. SUN has been using 2-mil laminates
from the mid 90s and I dont recall any manufacturing or reliability
issues. The 500V hi-pot testing weeds out potential problems early on.
By now the 2-mil ZBC2000 is readily available through a list of PCB
fabricators: you can check
http://www.sanmina-sci.com/Solutions/pdfs/pcbres/BC Licensed_lam.pdf On
the same Sanmina-SCI (now owner and keeper of the original Unisys/Zycon
technology) website you will find a "Buried Capacitance® & Embedded
Passives" section with more info.
1-mil and thinner laminates are mostly available in unreinforced form
(no glass), though a 1-mil version of the 2-mil ZBC2000 laminate was
(and probably still is) available. You can find more info at:
- DuPont Interra: http://www2.dupont.com/Interra/en_US/
-Oak-Mitsui FaradFlex: http://www.faradflex.com/
- 3M Embedded Capacitance Material:
http://solutions.3m.com/wps/portal/3M/en_WW/electronics/home/productsandservices/products/MicrointerconnectSolutions/EmbeddedCapacitanceMaterial/
The unreinforced resin has significant dielectric strength in the
thousands of volts per mil, so that is usually not an issue. SUN has
been using 1-mil DuPont HK04 and Oak-Mitsui BC24 laminates over the past
six years with no issues. You can find more papers on the subject at
http://www.electrical-integrity.com/ >> Paper download:
- DesignCon2006, Santa Clara, CA, February 6-9, 2006, "SUN’s Experience
with Thin and Ultra Thin Laminates for Power Distribution Applications,"
in TecForum TF-THA2 "SUN's Experience with Thin and Ultra Thin Laminates
for Power Distribution Applications"
- DesignCon2004, High-Performance Systems Design Conference, Santa
Clara, CA, Feb 2-5, 2004, "Thin and Very Thin Laminates for Power
Distribution Applications: What is New in 2004?"
- DesignCon 2002, High-Performance System Design Conference, San Jose,
CA, January 28 - 31, 2002, "Thin PCB Laminates for Power Distribution -
How Thin is Thin Enough?"
Regards,
Istvan Novak
SUN Microsystems
Bowden, Ivor wrote:
> Hi SI people,
>
>
> Could I get some comments on the use of "thin" (<0.0035") dielectrics in
> PCBs, in terms of available materials, cost, reliability, dielectric
> strength, trace width vs dielectric constant, power plane capacitance,
> stories, studies, useful web links, any other pertinent issues? Base question
> is, could this be a practical way to increase PCB layer count while
> maintaining overall PCB thickness?
>
>
>
> Any / all information / comments welcome.
>
>
>
> Thanks,
>
>
>
> Ivor Bowden
>
>
>
>
>
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