The Keithley 6517B Electrometer/High Resistance Meter is the worldwide research laboratory standard for sensitive measurements. With over 60 years of low-level measurement expertise, Keithley electrometers provide reliable measurements of current levels down to 10aA (10×10-18A,) charge levels down to 1fC, and the highest resistance measurements available up to 1018O. The 6517B is also capable of measuring the largest voltage range-up to 200V-with an input impedance exceeding 200TO.

Exceptional Performance Specification

The 6517B has incorporated Keithley's decades of expertise in low level measurement technology into an innovative, low current input amplifier with an input bias current of less than 3fA, just 0.75fAp-p noise, and less than 20μA burden voltage on the lowest current ranges. The voltage circuit input impedance is greater than 200TO for near-ideal circuit loading. These specifications ensure the accuracy and sensitivity needed for accurate low current and high impedance voltage, resistance, and charge measurements in areas of research such as physics, optics, nanotechnology, and materials science. A built-in +/-1 kV voltage source with sweep capability simplifies performing leakage, breakdown, and resistance testing, as well as volume (W-cm) and surface resistivity (w/square) measurements on insulating materials.

Wide Measurement Ranges

The 6517B offers autoranging over the full span of ranges on current, resistance, voltage, and charge measurements. The 6517B combines the following measurement capabilities:

- Ultra-sensitive ammeter with current measurement from 10aA to 20mA

- Highest impedance voltmeter with voltage measurement from 1μV to 200V

- Ultra-high range ohmmeter with resistance measurement from 1O to 1018O

- Sensitive coulombmeter with charge measurement from 1fC to 2μC

Improved High Resistivity Measurements

Many test applications require measuring high levels of resistivity (surface or volume) of materials. The conventional method of making these measurements is to apply a sufficiently large voltage to a sample, measure the current that flows through the sample, then calculate the resistance using Ohm's Law (R=V/I.) While high resistance materials and devices produce very small currents that are difficult to measure accurately, Keithley electrometers and picoammeters are used successfully for such measurements.

Even with high quality instrumentation, inherent background currents in the material can make these measurements difficult to perform accurately. Insulating materials, polymers, and plastics typically exhibit background currents due to piezoelectric effects, capacitive elements charged by static electricity, and polarization effects. These background currents are often equal to or greater than the current stimulated by the applied voltage. In these cases, the result is often unstable, providing inaccurate resistance or resistivity readings or even erroneous negative values. Keithley's 6517B is designed to solve these problems and provides consistent, repeatable, and accurate measurements for a wide variety of materials and components.

Alternating Polarity Method for High Resistance Measurements

The 6517B uses the Alternating Polarity Method, which virtually eliminates the effect of any background currents in the sample. First and second order drifts of the background currents are also canceled out. The Alternating Polarity Method applies a voltage of positive polarity, then the current is measured after a specified delay (Measure Time). Next, the polarity is reversed and the current measured again, using the same delay. This process is repeated continuously, and the resistance is calculated based on a weighted average of the four most recent current measurements. This method typically produces a highly repeatable, accurate measurement of resistance (or resistivity) by the seventh reversal on most materials (i.e., by discarding the first three readings).

Simple DMM-like Operation

The 6517B is designed for easy, DMM-like operation via the front panel, with single-button control of important functions such as resistance measurement. Also, all the functions of the 6517B can be programmed through either the RS-232 interface or the GPIB (IEEE-488) interface.

High Accuracy High Resistance Measurements

The 6517B offers a number of features and capabilities that help ensure the accuracy of high resistance measurement applications. For example, the built-in voltage source simplifies determining the relationship between an insulator's resistivity and the level of source voltage used. It is wellsuited for capacitor leakage and insulation resistance measurements, tests of the surface insulation resistance of printed circuit boards, voltage coefficient testing of resistors, and diode leakage characterization.

Temperature and Humidity Stamping

Humidity and temperature can influence the resistivity values of materials significantly. To help you make accurate comparisons of readings acquired under varying conditions, the 6517B offers a builtin type K thermocouple and an optional 6517-RH Relative Humidity Probe. A built-in 50,000 reading data storage buffer allows recording and recalling measurements stamped with the time of the measurement, the temperature, and the relative humidity.

Internal Test Sequences Expand and Simplify Applications

The 6517B has a number of internal test sequences that assists in easily setting up and performing a number of tests. Device characterization sequences include diode leakage current measurement, capacitor leakage current measurement, cable insulation resistance measurement, and resistor voltage coefficient measurement. Resistivity and resistance tests include volume resistivity, surface resistivity, and surface insulation resistance testing. Parameters can be characterized as a function of voltage with the square wave and staircase test sequences.

In addition to its built-in tests, the 6517B excels in low current, high impedance voltage, resistance, and charge measurements in areas of research such as physics, optics, and materials science. The electrometer's extremely low voltage burden makes it particularly valuable for use in solar cell characterization applications and its built-in voltage source and low current sensitivity make it an excellent solution for high resistance measurements of nanomaterials such as polymer- based nanowires, other nanomaterials, ceramics, dielectric films, and biomaterials.

With its highly responsive measurements and DMM-like operation, the 6517B performs well in quality control, design engineering, and production test applications involving leakage current, breakdown, and resistance testing. Volume and surface resistivity measurements on non-conductive materials are particularly enhanced by the 6517B's voltage reversal method. The 6517B is also excellent for electrochemistry applications such as high impedance, ion-selective electrodes and pH measurements, conductivity cells, and potentiometry.