Ultra-High Precision Hermetically Sealed Bulk Metal
®
Foil Resistor
with Zero TCR
, no Humidity Effect and 0.005 % Tolerance within a
Unique Construction, Minimizing the Effects of Stress Factors
VHP100
Vishay Foil Resistors
Document Number: 63003 For any questions, contact: foil@vishaypg.com www.foilresistors.com
Revision: 23-Mar-10 1
INTRODUCTION
The new VHP100 type represents a metrology breakthrough.
A new construction concept combined with special
treatments make this resistor the first choice in the most
demanding instrumentation and laboratory applications.
The ability of the new VHP100 to minimize the changes in
resistance value when the resistor is subjected to load
variations and thermal stresses, ensure the ultra high
performances for the tight metrology specifications.
The total error budget of 2 ppm drift and the high speed
recovery represent an improvement of almost an order of
magnitude on the earlier model.
Vishay has achieved an essentially Zero Temperature
Coefficient Resistor in the VHP100 type. This oil filled
hermetically sealed device makes unique use of foil on
ceramic in such a way that self cancelling responses to
temperature are produced by combining equal and opposite
effects. This product is sold only in hermetic packages
because applications requiring this level of temperature
stability require humidity stability as well.
The value of the hermetic enclosure over the molded part is
in the long term performance. The hermetic sealing prevents
the ingress of moisture and oxygen, while the oil acts as a
thermal conductor.
TCR WINDOW DEFINITION
The TCR of the VHP100 is so small that an additional
definition - window, has been introduced. The window
definition requires that the absolute resistance remain within
the stated window over the temperature range specified. The
resistance of the VHP100 resistor stays within a 60 ppm
window over the entire military temperature range of - 55 °C
to + 125 °C (figures 1 and 3).
A window of 10 ppm is available for the laboratory instrument
range (+ 15 °C to + 45 °C); see figure 4 - type VHP101.
TCR TRACKING
Tracking of the VHP100 resistor is also vastly superior to
conventional precision resistors. Typical ± 5 ppm/°C precision
resistors have a worst-case tracking of 10 ppm/°C
(wirewounds, thick film, thin film) or a difference between
resistors of 1000 ppm (10 ppm/°C x 100 °C) when
temperature changes from + 25 °C to + 125 °C. For a
3 ppm/°C tracking (Vishay S102C) the difference will be
300 ppm (3 ppm/°C x 100 °C) for the same temperature
range. The VHP100 resistors will track to 60 ppm from - 55 °C
to + 125 °C, a five-fold improvement over the S102C resistor.
FEATURES
• Essentially zero TCR
• Absolute resistance change (window):
VHP100 < 60 ppm (- 55 °C to + 125 °C)
VHP101 < 10 ppm (+ 15 °C to + 45 °C)
• Tolerance: to ± 0.005 % (50 ppm) - (available to
± 0.001 % (10 ppm))
• No humidity effect: hermetically sealed against moisture
• Load life stability: ± 50 ppm typical for 2000 h, 70 °C at
0.3 W
• Shelf life stability: ± 2 ppm typical after at least 6 years
• Resistance range: 100 Ω to 150 kΩ (higher or lower values
available on request)
• 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)
• Electrostatic discharge (ESD) up to 25 000 V
• Non inductive, non capacitive design
• Rise time: 1 ns effectively no ringing
• Thermal stabilization < 1 s
• Current noise: 0.010 µV
RMS
/V of applied voltage (< - 40 dB)
• Thermal EMF: 0.05 µV/°C typical
• Voltage coefficient: < 0.1 ppm/V
• Inductance: < 0.08 µH
• Non hot spot design
• Hermeticity: 10
-7
atmospheric cc/s max.
• Terminal finish: lead (Pb)-free, tin/lead alloy
• Compliant to RoHS directive 2002/95/EC
• Oil filled as standard, air filled available upon request
• Load-life stability can be considerably improved through
in-house oriented tests
POST MANUFACTURING OPERATIONS
ENHANCE THE ALREADY GREATER
STABILITY OF FOIL RESISTORS
These PMO operations are uniquely applicable to resistors
made of resistive foil and they take the already superior
stability of foil devices one step further. The PMO operations
described are not applicable to thick film, thin film, or wire.
They constitute an exercising of the resin that bonds the foil
to the substrate.
The exercises that are employed are (1) temperature cycling
(2) short time overload, and (3) accelerated load life.
TEMPERATURE CYCLING
This exercise is done initially in the chip stage of all
production and will eliminate any fallout in the PMO cycling.
The cycling exercises the bonding resin and relaxes the foil
without reducing the bonding strength. A small reduction in
resistance is tolerable during this PMO operation.
* Pb containing terminations are not RoHS compliant, exemptions may apply
