OL1.NOV–Zycon–SC
Pc-board capacitance without a capacitor
Technique achieves required capacitance without discrete capacitors
Circuit board designers maintain an ongoing quest to maximize circuit
performance while minimizing board density. Embedding a thin capacitance
layer in the board can help attain these goals.
Multilayer pc boards often use bypass capacitors between the voltage and
ground planes to provide a source of local charge as well as to stabilize
the voltage level across the planes. But Zycon, a pc-board fabricator in
Santa Clara, CA, recently went into full production on its newly patented
Buried Capacitance technology. This technique produces capacitance not
through discrete capacitors, but via a capacitance layer buried in the pc
board.
A thin dielectric composite of epoxy-impregnated glass fibers,
typically 0.062 in.thick, but varying in thickness depending on the
application, achieves the desired capacitance. All the problems associated
with using discrete bypass capacitors–the pads and conductors occupied by
them, as well as the placement, soldering, inspection, and testing of the
capacitors–are eliminated. The capacitance layer can also free valuable
pc-board space or enable the designer to build boards that are smaller or
have fewer layers, says the company.
The Buried Capacitance material is imaged using existing customer power
and ground artwork designs and is placed between the voltage and ground
layers. It is then laminated as an integral part of the pc board. Preliminary test results with the Buried Capacitance material have shown no
adverse effect on product performance factors like EMI emissions and
long-term life.
Zycon has been developing the Buried Capacitance technology for several
years but only recently has overcome all the physical constraints in
manufacturing pc boards with the thin capacitive layer. The company can
now build boards up to 19 x 25 in.with up to 16 layers.
Besides its in-house manufacturing capability, Zycon is making the
Buried Capacitance technology available through licensees. Four companies
have already agreed to do so: Automata, of Sterling, VA; Hewlett-Packard,
of Sunnyvale, CA; Trend Circuits, of Fremont, CA; and ADI/Isola, also of
Fremont. Zycon is seeking others interested in licensing the technology.
For more information, contact Robert Terrazas of Zycon Corp., Santa
Clara, CA, at 408-243-1976, ext. 5039, or . –Spencer Chin
CAPTION:
A patented Buried Capacitance technology from Zycon employs a thin
dielectric composite layer embedded between the voltage and ground planes.
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