Hermetically Sealed Ultra-High-Precision Bulk Metal Foil Four-Resistor Network

In addition, the device features excellent shelf-life stability per resistor of 0.0002 % (2 ppm) and a shelf life stability ratio of 0.0001 % (1 ppm) for at least six years. In addition to these tight stability characteristics, the SMNH combines a low absolute TCR of ± 2 ppm/°C typical from - 55 °C to + 125 °C, + 25 °C ref., TCR tracking of ± 0.5 ppm/°C typical, and a tolerance match down to ± 0.005 % (50 ppm) in an 8-pin, surface-mount, ceramic gull wing package.



The SMNH resistor network combines four independent Bulk Metal Foil resistors in a single surface-mount package. Offering better performance and more efficient use of board space than discrete resistors and matched sets, the device can be used independently or as divider pairs.



The ceramic gull wing package of the SMNH offers the advantages of electrical isolation on the underside of the device and high heat dissipation capability, while the network’s hermetic sealing enhances its already inherently stable environmental performance.



With a wide resistance range of 5 Ω to 33 kΩ, the SMNH offers resistance ratios from 1:1 to 100:1. Vishay Foil resistors are not restricted to standard values, and can be specified to “as-required” values (e.g., 1.2345 kΩ vs. 1 kΩ) at no extra cost or delivery time.



While other resistor technologies can take several seconds or even minutes to achieve a steady state thermal stabilization, the SMNH network has an almost instantaneous thermal stabilization time of < 1 s, and a nearly immeasurable 1.0-ns rise time, effectively without ringing.



The device features a power rating of 0.4 W (or 0.1 W per resistor) at 70 °C, current noise of less than -40 dB, and a voltage coefficient of < 0.1 ppm/V. The network offers a non-inductive, non-hot-spot design, and the utmost in ESD immunity, withstanding electrostatic discharges up to 25 kV, for increased reliability.



All the resistors inside the SMNH are produced from the same proprietary Bulk Metal Foil alloy, of known and controllable characteristics. The alloys, which are not deposited by conventional techniques, are approximately 100 times thicker than conventional evaporated films. Vishay resistor elements are then photo-etched into a variety of resistive patterns in such a way that the resistance is adjustable to a standard tolerance of 0.01 % (100 ppm), and to 0.005 % (50 ppm) by request.



Through the entire process, every step is carefully controlled not only to keep the metal in its pure state, but also to eliminate the effects of any stress that might be imposed either during manufacture or use.



Vishay hermetic resistor networks are based on fabrication from a standing inventory of resistor chips. This permits quick delivery of prototypes since there are no masks to design or trial processing to be made. There are normally no engineering or setup charges, and no minimum quantities are required. The finished product provides the stability associated with Foil resistors in a miniature hermetically sealed package.



The network features gold-plated lead (Pb)-free terminations, and is available with Z-Foil technology for improved TCR to ±0.05 ppm/°C.