CAMBRIDGE, UK Vishay's latest generation of hermetically sealed, ultra-high precision bulk metal foil resistors features very low temperature coefficients and are manufactured to very high tolerances.
TCR range from ± 0.2 ppm/degree C, Tolerance is of ± 0.001 percent (10 ppm), and load-life stability of ± 0.002 percent (20 ppm) at +25 degree C for 2000 hours at rated power.
The secondary-standard, hermetically sealed, oil-filled bulk metal foil resistors, namely the H and HZ series feature come in a resistance range of 5 Ohm to 1.84 MOhm, a shelf-life stability of 2 ppm (±0.0002 percent) for at least 6 years (unaffected by humidity), and a rise time of less than 1ns.
Maximum TCR ranges from ±2 ppm/ degree C for the H series to ±0.2 ppm/ degree C for the Z-Foil HZ series.
The H and HZ products offer an immediate answer to many challenging resistor applications such as including resistance standards, feedback devices for operational amplifiers, precision voltage dividers, meter multipliers, precision bridge resistors, and decade voltage dividers.
In both "H" family product series, the resistive element is mounted on a PCB board to which axial leads are anchored. The electrical connection between the resistive element and the leads is provided through a special low-stress construction.
After the assembly is inserted into a tinned brass shell, moisture is removed from inside the package using a proprietary process, and the unit is oil-filled and solder-sealed to permit uniform heat dissipation and minimize the effects of extreme environments.
The hermetic sealing eliminates the ingress of moisture and oxygen, while the oil acts as a thermal conductor. "H" family devices are also available with laboratory- and metrology-level precision and long-term stability with additional in-house oriented processes such as chip stabilization, special TCR plotting, additional treatments for ultra-stability, and special post manufacturing operations (PMO), such as temperature cycling, short-time overload, and accelerated load life.
Special construction allows the devices' copper leads to pass through the seal to the outside of the enclosure. This positions the more malleable solder-coated copper leads on the outside of the package and minimizes the thermal EMF at the internal termination-to-resistor junction assembly.
With the H and HZ series resistors, only a minimal shift in resistance value will occur during their entire lifetime. Most of the shift takes place during the first few hundred hours of operation and virtually no change is noted thereafter.
This change can be eliminated with additional PMO as mentioned above. Please contact our engineers to provide the suitable PMO profile for your application.
"H" family devices feature a electrostatic discharge protection up to 25 kV, a rise time of 1 ns, with essentially no ringing, current noise of less than -40 dB, thermal EMF of 0.05 microV/ degree C typical, and a voltage coefficient of less than 0.1 ppm/V.
Note that Vishay Foil resistors are not restricted to standard values. Specific values can be supplied at no extra cost or delivery time.
Check the link to the datasheets