Accu-F® / Accu-P®
Thin-Film Technology
THE IDEAL CAPACITOR
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The non-ideal characteristics of a real capacitor can be
ignored at low frequencies. Physical size imparts inductance
to the capacitor and dielectric and metal electrodes result in
resistive losses, but these often are of negligible effect on the
circuit. At the very high frequencies of radio communication
(>100MHz) and satellite systems (>1GHz), these effects
become important. Recognizing that a real capacitor will
exhibit inductive and resistive impedances in addition to
capacitance, the ideal capacitor for these high frequencies is
an ultra low loss component which can be fully characterized
in all parameters with total repeatability from unit to unit.
Until recently, most high frequency/microwave capacitors
were based on fired-ceramic (porcelain) technology. Layers
of ceramic dielectric material and metal alloy electrode paste
are interleaved and then sintered in a high temperature oven.
This technology exhibits component variability in dielectric
quality (losses, dielectric constant and insulation resistance),
variability in electrode conductivity and variability in physical
size (affecting inductance). An alternate thin-film technology
has been developed which virtually eliminates these variances. It is this technology which has been fully incorporated
into Accu-F® and Accu-P® to provide high frequency capacitors exhibiting truly ideal characteristics.
The main features of Accu-F® and Accu-P® may be summarized as follows:
• High purity of electrodes for very low and repeatable
ESR.
• Highly pure, low-K dielectric for high breakdown field,
high insulation resistance and low losses to frequencies
above 40GHz.
• Very tight dimensional control for uniform inductance,
unit to unit.
• Very tight capacitance tolerances for high frequency
signal applications.
This accuracy sets apart these Thin-Film capacitors from
ceramic capacitors so that the term Accu has been
employed as the designation for this series of devices, an
abbreviation for “accurate.”
THIN-FILM TECHNOLOGY
Thin-film technology is commonly used in producing semiconductor devices. In the last two decades, this technology
has developed tremendously, both in performance and in
process control. Today’s techniques enable line definitions of
below 1μm, and the controlling of thickness of layers at 100Å
(10-2μm). Applying this technology to the manufacture of
capacitors has enabled the development of components
where both electrical and physical properties can be tightly
controlled.
The thin-film production facilities at AVX consist of:
• Class 1000 clean rooms, with working areas under
laminar-flow hoods of class 100, (below 100 particles
per cubic foot larger than 0.5μm).
• High vacuum metal deposition systems for high-purity
electrode construction.
• Photolithography equipment for line definition down to
2.0μm accuracy.
• Plasma-enhanced CVD for various dielectric depositions (CVD=Chemical Vapor Deposition).
• High accuracy, microprocessor-controlled dicing saws
for chip separation.
• High speed, high accuracy sorting to ensure strict
tolerance adherence.
TERMINATION
ALUMINA
ELECTRODE
SEAL
ELECTRODE
DIELECTRIC
ALUMINA
ACCU-P® CAPACITOR
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