Ultra High Precision Z-Foil Resistor with TCR of ± 0.05 ppm/°C,
Tolerance of ± 0.005 % (50 ppm), Load Life Stability of ± 0.005 %,
ESD Immunity up to 25 kV and Thermal EMF of 0.05 µV/°C
Z Series (Z-Foil)
Vishay Foil Resistors
Document Number: 63187 For any questions, contact: foil@vishaypg.com www.foilresistors.com
Revision: 21-Jul-10 1
INTRODUCTION
The Bulk Metal® Foil resistor is based on a special concept
where a proprietary bulk metal cold rolled foil is cemented to
a ceramic substrate. It is then photoetched into a resistive
pattern. Furthermore, it is laser adjusted to any desired value
and tolerance. Because the metals used are not drawn,
wound or mistreated in any way during manufacturing
process, the Bulk Metal Foil resistor maintains all its design,
physical and electrical characteristics while winding of wire
or sputtering does not. Z foil resistors achieve maximum
stability and near-zero TCR. These performance
characteristics are built-in for every unit, and do not rely on
screening or other artificial means for uniform performances.
The stability of a resistor depends primarily on its history of
exposures to temperature. Stability is affected by:
1. Changes in the ambient temperature and heat from
adjacent components (defined by the Temperature
Coefficient of Resistance, or TCR)
2. Destabilizing thermal shock of suddenly-applied power
(defined by the power coefficient, or PCR)
3. Long-term exposure to applied power (load-life stability)
4. Repetitive stresses from being switched on and off
In very high-precision resistors, these effects must be taken
into account to achieve high stability with changes in load
(Joule Effect) and ambient temperature.
Vishay’s new Z-Foil technology provides an order of
magnitude reduction in the Bulk Metal Foil element’s
sensitivity to temperature changes - both external and
internal. This technology provides an absolute TCR of
± 0.05 ppm/°C typical (instrument range: 0 °C to +60 °C),
± 0.2 ppm/°C typical (military range: - 55 °C to + 125 °C,
+ 25 °C ref), and a PCR of 5 ppm at rated power.
In order to take full advantage of this TCR improvement, it is
necessary to take into account the differences in the
resistor’s response to each of the above-mentioned effects.
The Z series has been developed to successfully deal with
these factors.
TABLE 1 -
TYPICAL TCR AND MAX. SPREAD
(- 55 °C to + 125 °C, + 25 °C ref.)
VALUE STANDARD
TOLERANCE
TYPICAL TCR AND
MAX. SPREAD
(ppm/°C)
100 Ω to 600 KΩ± 0.005 % ± 0.2 ± 0.6
80 Ω to < 100 Ω± 0.005 % ± 0.2 ± 0.8
50 Ω to < 80 Ω± 0.01 % ± 0.2 ± 1.0
25 Ω to < 50 Ω± 0.01 % ± 0.2 ± 1.3
10 Ω to < 25 Ω± 0.02 % ± 0.2 ± 1.6
FEATURES
•Temperature coefficient of resistance (TCR):
- ± 0.05 ppm/°C typical (0 °C to + 60 °C)
- ± 0.2 ppm/°C typical (- 55 °C to + 125 °C,
+ 25 °C ref.) (see table 1)
•Rated power: to 1 W at + 125 °C
•Resistance tolerance: to ± 0.005 % (50 ppm)
•Load life stability: to ± 0.005 % at 70 °C, 2000 h or to
±0.015% at 70°C,10000 h (see table 4)
•Resistance range: 10 Ω to 600 kΩ
•Vishay Foil Resistors are not restricted to standard values;
specific “as required” values can be supplied at no extra
cost or delivery (e.g. 1K2345 vs. 1K)
•Total accumulated change in resistance over life (EOL)
< 0.05 % (or better with PMO)
•Electrostatic discharge up to 25 000 V
•Non-inductive, non-capacitive design
•Rise time: 1 ns effectively no ringing
•Current noise: 0.010 µVRMS/V of applied voltage (< - 40 dB)
•Thermal EMF: 0.05 µV/°C typical
•Voltage coefficient: < 0.1 ppm/V
•Low inductance: < 0.08 µH typical
•Thermal stabilization time < 1 s (nominal value achieved
within 10 ppm of steady state value)
•Pattern design minimizing hot spots
•Terminal finish: lead (Pb)-free or tin/lead alloy
•Matched sets are available per request
(TCR tracking: to 0.5 ppm/°C)
•Prototype quantities available in just 5 working days
or sooner. For more information, please contact
foil@vishaypg.com
•Load life ΔR maximum can be reduced significantly
with our post manufacturing operations (PMO) see
page 4 for details
FIGURE 1 - TYPICAL RESISTANCE/
TEMPERATURE CURVE (Z-FOIL)
+ 500
+ 200
+ 100
0
- 100
- 200
- 300
- 500
- 55 - 25 + 25 + 60 + 75 + 100 + 125
Ambient Temperature (°C) and TCR Chord Slopes
for Different Temperature Ranges
ΔR
R
(ppm)
0
0.05 ppm/°C
- 0.1 ppm/°C 0.1 ppm/°C
0.14 ppm/°C
0.2 ppm/°C - 0.16 ppm/°C
- 400
+ 300
+ 400
* Pb containing terminations are not RoHS compliant, exemptions may apply