Z Series (Z-Foil)
Vishay Foil Resistors
Ultra High Precision Z-Foil Though-Hole Resistor
with TCR of ± 0.05 ppm/°C, Tolerance of ± 0.005 % (50 ppm),
Load Life Stability of ± 0.005 %
FEATURES
Temperature coefficient of resistance (TCR):
- ± 0.05 ppm/°C nominal (0 °C to + 60 °C)
- ± 0.2 ppm/°C nominal (- 55 °C to + 125 °C,
+ 25 °C ref.) (see table 1)
Rated power: to 1 W at + 125 °C (see table 2)
Resistance tolerance: to ± 0.005 % (50 ppm)
Load life stability: ± 0.005 % at 70 °C, 2000 h or ±0.015%
at 70°C,10000 h (see table 4)
Resistance range: 5
to
600 k
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)
or Total Error Budget < 0.1 % (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 µV
RMS
/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 (to reach 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
INTRODUCTION
The Bulk Metal
®
Foil resistor is based on a special
thermo-metalic stress concept wherein a proprietary bulk
metal cold rolled foil is cemented to a ceramic substrate. It is
then photoetched into a resistive pattern. Then 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 performance.
The stability of a resistor depends primarily on its history of
exposures to temperature. Stability is affected by:
1. Reversible changes in the ambient temperature and heat
from adjacent components (defined by the Temperature
Coefficient of Resistance, or TCR)
2. Short-term steady-state self-heating (defined by Power
TCR or PCR)
3. Irreversible destabilizing shock of suddenly-applied
power
4. Long-term exposure to applied power (load-life stability)
5. 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 Foil Resistors’ 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 TCR of
± 0.05 ppm/°C nominal (instrument range: 0 °C to +60 °C),
± 0.2 ppm/°C nominal (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 - NOMINAL TCR AND MAX. SPREAD
(- 55 °C to + 125 °C, + 25 °C ref.)
VALUE
100
to 600 K
80
to < 100
50
to < 80
25
to < 50
10
to < 25
5
to < 10
STANDARD
TOLERANCE
± 0.005 %
± 0.005 %
± 0.01 %
± 0.01 %
± 0.02 %
± 0.05 %
NOMINAL TCR AND
MAX. SPREAD
(ppm/°C)
± 0.2 ± 0.6
± 0.2 ± 0.8
± 0.2 ± 1.0
± 0.2 ± 1.3
± 0.2 ± 1.6
± 0.2 ± 2.3
* Pb containing terminations are not RoHS compliant, exemptions may apply
** See PMO page 5
Document Number: 63187
Revision: 22-Oct-13
For any questions, contact:
foil@vishaypg.com
www.vishayfoilresistors.com
1
Z Series (Z-Foil)
Vishay Foil Resistors
FIGURE 1 - NOMINAL RESISTANCE/
TEMPERATURE CURVE
(for more details, see table 1)
+250
+200
+150
+100
0
R
(ppm)
-50
-100
-150
-200
-250
-55
- 0.16 ppm/ºC
-25
0
+25
+50
0.05 ppm/ºC
- 0.1 ppm/ºC
0.1 ppm/ºC
0.14 ppm/ºC
0.2 ppm/ºC
+65
+75
+100
+125
+250
+200
+150
+100
+50
0
-50
-100
-150
-200
-250
FIGURE 2 - POWER DERATING CURVE
100
- 55 °C
+ 70 °C
Rated Power
Rated Power (%) at + 70 °
75
50
Δ
R
25
0
- 75
- 50
- 25
0
+ 25 + 50 + 75 + 100 + 125 + 150 + 175 + 200
Ambient Temperature (°C)
Note
• The TCR values for < 100
are influenced by the termination
composition and result in deviation from this curve
FIGURE 3 - TRIMMING TO VALUES
(conceptual illustration)
Interloop
Capacitance
Reduction
in Series
Mutual Inductance
Reduction due
to Change in
Current Direction
Current Path
Before Trimming
Current Path After Trimming
Trimming Process
Removes this Material
from Shorting Strip Area
Changing Current Path
and Increasing
Resistance
Foil shown in black, etched spaces in white
Note
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 Vishay Foil resistor.
FIGURE 4 - THROUGH-HOLE STYLE (>29 YEARS)
40
20
0
-20
-40
-60
-80
ΔR/R (ppm)
-100
-120
0
5
10
15
20
25
30
Time (Years)
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2
For any questions, contact:
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Document Number: 63187
Revision: 22-Oct-13
Z Series (Z-Foil)
Vishay Foil Resistors
TABLE 2 - MODEL SELECTION
MODEL
NUMBER
RESISTANCE
RANGE
(2)
()
MAXIMUM
WORKING
VOLTAGE
AMBIENT
POWER RATING
at
+ 70 °C
at
+ 125 °C
AVERAGE
WEIGHT
(g)
DIMENSIONS
INCHES
W: 0.105 ± 0.010
L: 0.300 ± 0.010
H: 0.326 ± 0.010
ST: 0.010 min.
SW: 0.035 ± 0.010
LL: 1.000 ± 0.125
LS: 0.150 ± 0.005
(1)
W: 0.160 max.
L: 0.575 max.
H: 0.413 max.
ST: 0.035 ± 0.005
SW: 0.050 ± 0.005
LL: 1.000 ± 0.125
LS: 0.400 ± 0.020
W: 0.160 max.
L: 0.820 max.
H: 0.413 max.
ST: 0.035 ± 0.005
SW: 0.050 ± 0.005
LL: 1.000 ± 0.125
LS: 0.650 ± 0.020
W: 0.260 max.
L: 1.200 max.
H: 0.413 max.
ST: 0.035 ± 0.005
SW: 0.050 ± 0.005
LL: 1.000 ± 0.125
LS: 0.900 ± 0.020
mm
2.67 ± 0.25
7.62 ± 0.25
8.28 ± 0.25
0.254 min.
0.89 ± 0.13
25.4 ± 3.18
3.81 ± 0.13
4.06 max.
14.61 max.
10.49 max.
0.889 ± 0.13
1.27 ± 0.13
25.4 ± 3.18
10.16 ± 0.51
4.06 max.
20.83 max.
10.49 max.
0.889 ± 0.13
1.27 ± 0.13
25.4 ± 3.18
16.51 ± 0.51
6.60 max.
30.48 max.
10.49 max.
0.889 ± 0.13
1.27 ± 0.13
25.4 ± 3.18
22.86 ± 0.51
Z201
(Z201L)
(1)
5 to 100K
300
0.6 W
0.3 W
0.6
Z204
5 to 200K
350
1.0 W
0.5 W
1.4
Z205
5 to 300K
350
1.5 W
0.75 W
1.9
2.0 W
Z206
5 to 600K
500
1.0 W
4.0
up to 400K
1.0 W
0.5 W
over 400K
Note
(1)
(2)
0.200" (5.08 mm) lead spacing available - specify Z201L instead of Z201.
for non standard values please contact Application Engineering Department at
foil@vishaypg.com
FIGURE 5 - STANDARD IMPRINTING AND DIMENSIONS
Front View
L
VFR
XXXX
Z201
Date Code
10
10
Year Week
ST
1)
Model
Number
SW
Lead Material
#22 AWG Round
Solder Coated Copper
LL
W
Rear
View
Optional Customer Part Number
Print Specification, etc., if Required
XXXXXX
100R01
0.01%
Resistance
Value Code
Tolerance
H
LS
Note
1. The standoffs shall be so located as to give a lead clearance of 0.010" minimum between the resistor body and the printed circuit board
when the standoffs are seated on the printed circuit board. This is to allow for proper cleaning of flux and other contaminants from the unit
after all soldering processes.
Document Number: 63187
Revision: 22-Oct-13
For any questions, contact:
foil@vishaypg.com
www.vishayfoilresistors.com
3
Z Series (Z-Foil)
Vishay Foil Resistors
TABLE 3 - ENVIRONMENTAL PERFORMANCE COMPARISON
MIL-PRF-55182
CHAR J
Test Group I
Thermal shock, 5 x (- 65 °C to + 150 °C)
Short time overload, 6.25 x rated power
Test Group II
Resistance temperature characteristics
Low temperature storage (24 h at - 65 °C)
Low temperature operation
(45 min, rated power at - 65 °C)
Terminal strength
Test Group III
DWV
Resistance to solder heat
Moisture resistance
Test Group IV
Shock
Vibration
Test Group V
Life test at rated power / + 125°C
2000 h
10 000 h
Test Group Va
Life test at 2 x rated power / + 70°C, 2000 h
Test Group VI
High temperature exposure (2000 h at + 175 °C)
Test Group VII
Voltage coefficient
5 ppm/V
< 0.1 ppm/V
< 0.1 ppm/V
± 2.0 %
± 0.05 % (500 ppm)
± 0.1 % (1000 ppm)
± 0.5 %
± 0.005 % (50 ppm)
± 0.015 % (150 ppm)
± 0.5 %
± 2.0 %
± 0.005 % (50 ppm)
± 0.015 % (150 ppm)
± 0.015 % (150 ppm)
± 0.05 % (500 ppm)
± 0.2 %
± 0.2 %
± 0.002 % (20 ppm)
± 0.002 % (20 ppm)
± 0.01 % (100 ppm)
± 0.01 % (100 ppm)
± 0.15 %
± 0.1 %
± 0.4 %
± 0.002 % (20 ppm)
± 0.005 % (50 ppm)
± 0.01 % (100 ppm)
± 0.01 % (100 ppm)
± 0.01 % (100 ppm)
± 0.05 % (500 ppm)
± 25 ppm/°C
± 0.15 %
± 0.15 %
± 0.2 %
± 0.05 ppm/°C
± 0.002 % (20 ppm)
± 0.002 % (20 ppm)
± 0.002 % (20 ppm)
see table 1
± 0.01 % (100 ppm)
± 0.01 % (100 ppm)
± 0.01 % (100 ppm)
± 0.2 %
± 0.2 %
± 0.002 % (20 ppm)
± 0.003 % (30 ppm)
± 0.01 % (100 ppm)
± 0.01 % (100 ppm)
Z SERIES
TYPICAL
R
Z SERIES
MAXIMUM
R
STANDARD OPERATIONS AND TEST
CONDITIONS
A. Standard Test Operations:
By 100 % Inspection
Short-time overload (6.25 x rated power for 5 s)
Resistance - tolerance check
LONG-TERM STABILITY
Some process controls are not very critical but many, many
are—particularly when a process is operating near a tipping
point where it could get out of control quickly if not well
monitored.
In process control applications, entire production batches
have been lost or suffered reduced reliability when critical
parameters were not kept within narrow limits. One thing that
can cause this to happen is changes in the precision resistor
over time. Reference points in the control process thus
become less and less reliable. Repeatability of the process
from batch to batch begins to drift. The process is changing
while the monitors appear to be holding it within specified
limits because the sense resistor is producing a different
output voltage than it was in previous runs for the same
sensor output. So the process appears to be under control
when, in reality, it is experiencing an undetected drift.
Visual and mechanical
By Sample Inspection
TCR
Environmental tests per table 3 on a quarterly basis
to establish performance by similarity
B. Standard Test Conditions:
Lead test point: 0.5" (12.7 mm) from resistor body
Temperature: + 23 °C ± 2 °C
Relative humidity: per MIL-STD-202
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For any questions, contact:
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Document Number: 63187
Revision: 22-Oct-13
Z Series (Z-Foil)
Vishay Foil Resistors
Long-term stability is thus one of the considerations that
drive the selection of which resistor technology to use in the
application.
But the typical permanent resistance drift of a Bulk Metal Foil
resistor is less than 60 ppm (0.006%) after 10 years running
at 0.1 W at 70°C.
HARMONIC DISTORTION
Harmonic distortion is an important consideration in the
choice of precision resistors for sensitive applications. A
significant signal voltage across the resistor may change the
resistance value depending on the construction, material,
and size. Under these conditions Bulk Metal Foil resistors
behave more linearly than other resistor types.
FIGURE 6 - LOAD LIFE TEST FOR 10000
HRS @ 0.3W +125°C; Z201,
N=24
300.0
200.0
100.0
R
(ppm)
0.0
250
500
1000
2000
4000
6000
8000
10000
100R
1K
10K
POWER COEFFICIENT OF RESISTANCE
(PCR)
The TCR of a resistor for a given temperature range is
established by measuring the resistance at two different
ambient temperatures: at room temperature and in a cooling
chamber or oven. The ratio of relative resistance change and
temperature difference gives the chord slope of
R/R
= f (T)
curve. This slope is usually expressed in parts per million per
degree Centigrade (ppm/°C). In these conditions, a uniform
temperature is achieved in the measured resistance. In
practice, however, the temperature rise of the resistor is also
partially due to self-heating as a result of the power it is
dissipating (self-heating). As stipulated by the Joule effect,
when current flows through a resistance, there will be an
associated generation of heat. Therefore, the TCR alone
does not provide the actual resistance change for precision
resistor. Hence, another metric is introduced to incorporate
this inherent characteristic – the Power Coefficient of
Resistance (PCR). PCR is expressed in parts per million per
Watt or in ppm at rated power. In the case of Z-based Bulk
Metal
®
Foil, the PCR is 5 ppm typical at rated power or 4 ppm
per Watt typical for power resistors.
–100.0
–200.0
–300.0
Time (hrs)
THERMAL EMF
In a resistor, the resistance is composed of a resistance
element of one material and two terminations of a different
material. When the junction of the element and the
termination is heated in a closed circuit, there is a DC voltage
generated in the circuit (see Seebeck and Peltier Effects).
Hence, if both termination junctions of the resistor are at
exactly the same temperature across terminations there is
no net thermal EMF voltage generated in the circuit due to
thermal EMF error voltages in the resistor.
In fact, however, the terminals are very seldom at the same
temperature because their temperatures are influenced by
uneven power dissipation within the resistor, differential
heating from other components on the board, and heat
conducted along the board itself. Obviously, in a sense
resistor that’s supposed to accurately convert a current to a
voltage, the presence of an extraneous thermal EMF voltage
could constitute a significant error source in the system. That
is why it’s important that Bulk Metal Foil resistors have a
thermal EMF voltage of less than 0.1 mV/°C difference
across the element to termination junction.
POST MANUFACTURING OPERATIONS
(PMO)
Many analog applications can include requirements for
performance under conditions of stress beyond the normal
and over extended periods of time. This calls for more than
just selecting a standard device and applying it to a circuit.
The standard device may turn out to be all that is needed but
an analysis of the projected service conditions should be
made and it may well dictate a routine of stabilization known
as post manufacturing operations or PMO. The PMO
operations that will be discussed are only applicable to Bulk
Metal
®
Foil resistors. They stabilize Bulk Metal Foil resistors
while they are harmful to other types. Short time overload,
accelerated load life, and temperature cycling are the three
PMO exercises that do the most to reduce drifts down the
road. VFR Bulk Metal Foil resistors are inherently stable as
manufactured. These PMO exercises are only of value on
Bulk Metal Foil resistors and they improve the performance
by small but significant amounts. Users are encouraged to
contact Vishay Foil Resistors’ applications engineering for
assistance in choosing the PMO operations that are right for
their application.
Document Number: 63187
Revision: 22-Oct-13
For any questions, contact:
foil@vishaypg.com
www.vishayfoilresistors.com
5
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