Hence, there is no need to use a large dc capacitor of several thousands of
microfarads in sustaining a constant dc voltage, and only a small dc capacitor of several tens of
microfarads is applied to act as a snubber and filter circuit.
The new Vishay Sprague SMD capacitor with capacitance values up to 2200
microfarads features a conductive polymer cathode technology that delivers low equivalent series resistance (ESR) values across a capacitance range from 47
microfarads to 2200
microfarads with a standard capacitance tolerance of plus/minus 20%.
The epoxy layers between the voltage plate and ground plates are "between about 0.005 inches and about 0.009 inches" thick "to establish a large distributed capacitance of about 0.03
microfarads between the voltage plate and ground plates." The patent further states that "the close spacing of a voltage layer between two ground layers provides a large distributed capacitance (without requiring many discrete isolation capacitors) which inhibits switching signals from causing voltage spikes in the power lines [power bus noise]." Mupac shipped millions of dollars of wire wrap boards using the Leary construction prior to 1989.
The upscale BC27pi has over 200,000
microfarads of capacitance and a separate power supply and sells for $1395.
Additional description of the Leary concept explains that the epoxy layers are "thin enough" to form a "large distributed capacitance" of at least 0.02
microfarads between the voltage plate and ground plates.
Figure 4, where epoxy layers (24), (26) are "thin enough" to establish "a large distributed capacitance" of at least 0.02
microfarads between the voltage plate (18) and ground plates (16), (20) (col.
Murata developed a thin-dielectric chip capacitance series said to offer 22
microfarads in an EIAJ-sized 2012 package and 10
microfarads in a 1608 sized-package.