VPG's Z-Foil Hybrid Chip Resistors Offer Low Typical TCR of 0.05ppm/°C from 0°C to +60°C, Tolerance to 0.005%, and Load-Life Stability of ±0.01% for 10,000 Hours

For hybrid applications, the new V5X5Z, V15X5Z, and V15X10Z resistors are available either factory trimmed to exact resistance values, or ready for user trimming after mounting with either gold or aluminum wire bonds. Vishay Foil Resistor chips can be trimmed after installation while monitoring the important output parameters of the circuit. Once calibrated, the value is permanently set and remains unaffected by shock, vibration, and temperature variations (external and internal). These capabilities bring high stability and reliability to system performance without any compromise between accuracy, stability, and speed. To acquire a precision resistance value, the Bulk Metal Foil chip is trimmed by selectively removing built-in shorting bars. To increase the resistance in known increments, marked areas are cut, producing progressively smaller increases in resistance. This method reduces the effect of hot spots and improves the long-term stability of the hybrid chips.

The Vishay Foil Resistor precision trimming system allows for adjustment to precise resistance values without concern over mechanical override and control problems encountered in laser or air-abrade trimming of solid geometry resistance patterns. This ability to trim resistor chips to tolerance levels never before available to hybrid manufacturers gives project managers the ability to increase the value-added level of their hybrid services and retain more profit within the facility. Instead of buying precision resistors in separate packages or modules — which require additional PCB real estate — and integrating them into a system, the project manager can utilize Vishay Foil Resistors' precision chips or matched sets to manufacture the entire hybrid circuit in-house. The devices also eliminate the need to pin out for precision resistor requirements, as the precision resistors are part of the hybrid microcircuit design.

The V5X5Z, V15X5Z, and V15X10Z offer a resistance range from 5Ω to 60kΩ. The resistors are not restricted to standard values, and specific as required values (e.g. 1.234kΩ vs. 1kΩ) can be supplied at no extra cost or delivery time. The devices feature power ratings from 50mW to 150mW at +70°C, a rise time of 1ns, with effectively no ringing, thermal stabilization time of <1s (nominal value achieved within 10ppm of steady state value), short-time overload ≤0.02%, and current noise of <-40dB.

In analog circuits, the most important factor is the end-of-life tolerance, which is part of the stability and, to a lesser extent, the initial tolerance. Foil hybrid Z-Foil chips provide stabilities well under the maximum allowable drift required by customers' specifications through thousands of hours of operation under harsh conditions such as the extreme temperatures and radiation-rich environments of down-hole oil well logging applications; in the frigid arctic; under the sea; or in deep space. All Bulk Metal Foil resistors receive stabilization processing such as repetitive short-term power overloads to assure reliable service through the unpredictable stresses of extreme operation.

Offering the utmost in ESD immunity, the V5X5Z, V15X5Z, and V15X10Z withstand electrostatic discharges at least to 25kV, for increased reliability, and offer a non-inductive (<0.08μH), non-capacitive design. Hybrid chips with Z-Foil are also available for high-temperature applications above +220°C. Applications Engineering assistance is also available to help with custom designs for multiple resistors on a single chip. Such services, for example, have produced up to 16 resistors within 0.01% tolerance and TCR tracking of less than 0.1ppm/°C on a single quarter-inch square chip. Contact VPG for more details.