VPG unveil flip-chip 0805 resistor with stability to ±0.005%

Based on VFR's next-generation Bulk Metal Z1-Foil technology, the FRFC 0805 excels over all previous stability standards for precision resistors with an order of magnitude improvement in high-temperature stability, load-life stability, and moisture resistance. These new benchmark levels of performance provide design engineers with the tools to build circuits not previously achievable while reducing costs and space in the most critical applications by eliminating the need for corrective circuitry and reducing the large land patterns needed for a wrap-around configuration. The device's flip-chip configuration saves up to 35% PCB space compared with a surface-mount chip with wraparound terminations while also providing strain relief to eliminate cracked substrates and board delamination.

In addition to its remarkably improved load-life stability, the FRFC 0805 is noise-free and provides ESD protection of 25 kV or more for increased reliability. The device's solid element alloy is matched to the substrate, forming a single entity with balanced resistance versus temperature characteristics for an unusually low and predictable TCR over a wide temperature range from -55°C to more than +125°C. The adhesive that holds the foil to the flat substrate withstands high temperatures, pulsing power, moisture incursions, shock and vibration, and low-temperature exposure while still holding securely to the foil element. Resistance patterns are photo-etched into the element to permit the trimming of resistance values to very tight tolerances as low as 0.01%.

Allowances in total error budget must be made for the stresses — especially mounting and thermal cycling for surface-mount devices — that will change a resistor's end-of-life tolerance, said Yuval Hernik, senior director of application engineering for VFR. These allowances depend on the specific resistor application and the service conditions in which the equipment is installed. The less stable a resistor is, the more allowance for instability is required. These allowances are considered cumulative, and when subtracted from the end-of-life error budget, they impose a tighter tolerance at the point of purchase.

The combination of flip-chip terminations and Z1-Foil construction and materials results in the most stable resistors available, requiring the lowest error allowance. This means that more error allowance can be transferred to active devices — resulting in lower costs — or applied to the foil resistors themselves, allowing for looser initial tolerances than would be required for other resistor technologies.

The FRFC devices are qualified as anti-sulfurated resistors for use in environments with high levels of contamination. Such environments include alternative energy applications, industrial control systems, sensors, RTDs, electric instrumentation, weather and communication base stations, and any electronic appliance used in high concentrations of sulfur.

The FRFC 0805 offers a wide resistance range from 5 Ω to 8 kΩ. Any resistance value within this range is available at any tolerance with no additional cost or lead time effect. The resistor features power ratings to 200 mW at +70°C, a rise time of 1.0 ns with effectively no ringing, a thermal stabilization time of <1 s (within 10 ppm of steady state value), current noise of 0.010 μVrms/V of applied voltage (<-40 dB), and a voltage coefficient of <0.1 ppm/V. The RoHS-compliant device offers a non-inductive (<0.08 μH), non-capacitive design and is available in matched sets upon request.

Samples and production quantities of the FRFC 0805 are available now, with lead times of five working days for samples and five weeks for larger orders.