Accu-F

®

/ Accu-P

®

Thin-Film Technology

THE IDEAL CAPACITOR

The non-ideal characteristics of a real capacitor can beignored 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 capacitorswere based on fired-ceramic (porcelain) technology. Layers of ceramic dielectric material and metal alloy industrial electrode paste are interleaved and then sintered in a high temperature industrial 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 vari- ances. It is this technology which has been fully incorporated into Accu-F

THIN-FILM TECHNOLOGY

1

Thin-film technology is commonly used in producing semi- conductor 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
-2 µm). Applying this technology to the manufacture ofcapacitors 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 cleaning rooms, with working areas underlaminar-flow hoods of class 100, (below 100 particles per cubic foot larger than 0.5µm).• High vacuum metal deposition systems for high-purityelectrode construction.• Photolithography equipment for line definition down to2.0µm accuracy.• Plasma-enhanced CVD for various dielectric deposi-tions (CVD=Chemical Vapor Deposition).• High accuracy, microprocessor-controlled dicing sawsfor chip separation.• High speed, high accuracy sorting to ensure strict tolerance adherence.
® and Accu-P
® to provide high frequency capaci-tors exhibiting truly ideal characteristics.The main features of Accu-F
® and Accu-P
® may be summa-rized as follows:• High purity of electrodes for very low and repeatableESR.• 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 frequencysignal applications. This accuracy sets apart these Thin-Film manufacturers of capacitors fromceramic capacitors so that the term Accu has been employed as the designation for this series of devices, an abbreviation for “accurate.”
TERMINATION ALUMINA ELECTRODE SEALELECTRODE DIELECTRICALUMINA ACCU-P CAPACITOR ®

6