FRSM Series
(Z1 Foil Technology)
Ultra High-Precision FRSM Wrap-Around Chip Resistors,
UltraHigh-PrecisionFRSMWrap-AroundChipResistors, FoilT
Z1 echnologyConfiguration
Z1 Foil Technology Configuration
with TCR of ±0.05 ppm/°C and
Improved Load-Life Stability of 0.0025% (25 ppm)
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.)
• Resistance tolerance: to ±0.01%
• Power coefficient “∆R due to self heating”: 5 ppm at
rated power
• Power rating: to 750 mW at +70°C
•
Load life stability:
±0.0025% typical at 70°C, 2000 h at rated power
±0.005% typical at 70°C, 10,000 h at rated power
• Resistance range: 5 Ω to 125 kΩ (for higher and lower
values, please contact us)
• Bulk Metal 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)
• Thermal stabilization time: <1 s (nominal value achieved
within 10 ppm of steady state value)
• Electrostatic discharge (ESD): at least to 25 kV
• Short time overload: ≤0.005% typical
• Rise time: 1 ns, effectively no ringing
• Current noise: <0.010 μV
RMS
/V of applied voltage
(<–40 dB)
• Voltage coefficient: <0.1 ppm/V (resistance values
above 10 kΩ)
• Non-inductive: 0.08 μH
• Non-hot spot design
• Terminal finishes available: lead (Pb)-free, tin/lead alloy
*
• Matched sets are available on request
• Screening in accordance with EEE-INST-002 and
MIL-PRF-55342 available (see datasheet resistor
models 303261 to 303266)
• Quick prototype quantities available, please contact us.
Top View
INTRODUCTION
The ultra high precision FRSM is based on the new
generation Z1 Foil Technology of the Bulk Metal
®
Foil
resistor elements by Vishay Foil Resistors (a VPG brand),
which makes these resistors virtually insensitive to
destabilizing factors (for more information about stresses
and destabilizing factors please refer to Tech Note 102:
www.vishaypg.com/doc?63135).
Their element, based on
the Z1 Foil Technology is a solid alloy that displays the
desirable bulk properties of its parent material; thus, it is
inherently stable (remarkably improved load life stability
of 25 ppm), noise-free and withstands ESD to 25 kV or
more. The alloy is matched to the substrate and forms a
single entity with balanced temperature characteristics for
an unusually low and predictable TCR over a wide range
from –55°C to more than 175°C. Resistance patterns are
photo-etched to permit trimming of resistance values to
very tight tolerances.
Our application engineering department is available to
advise and make recommendations. For non-standard
technical requirements and special applications, please
contact us using the e-mail address in the footer below.
Table 1—Tolerance and TCR vs.
Resistance Value
Resistance Value
(Ω)
250 to 125k
100 to <250
50 to <100
Tolerance
(%)
±0.01%
±0.02%
±0.05%
±0.1%
±0.25%
±0.5%
Typical TCR
and Spread
(ppm/°C)
(1)
*
This datasheet provides information about parts that are
RoHS-compliant and/or parts that are non-RoHS-compliant.
For example, parts with lead (Pb)terminations are not RoHS
compliant. Please see the information/tables in this datasheet
for details.
25 to <50
10 to <25
5 to <10
(1)
±0.05 ±0.5
From 0°C to 60°C
4220-EN
Rev 21-Aug-2020
For any questions, contact
foil@vpgsensors.com
www.vishayfoilresistors.com
1
FRSM Series
ABOUT THE FRSM SERIES
Several factors need to be considered when choosing a
resistor for applications that require long term stability,
including TCR (ambient temperature), Power TCR (self
heating), load-life stability for more than 10K hours
(instead of the typical 1000 or 2000 hours load-life),
end-of-life tolerance (which is more important than
the initial tolerance), thermal EMF (low values, D.C),
thermal stabilization and ESD. Some precision resistor
technologies such as Precision Thin Film offer designers
tight initial tolerances as low as 0.02 % but have poor
load life stability, high end-of-life tolerance, long thermal
stabilization, high drifts during operational life and
ESD sensitivity. Other resistor technologies, such as
Wirewounds, provide low absolute TCR and excellent
current noise of -40 dB but have high inductance and
poor rise time (or thermal lag) for more than a few
seconds.
There are essentially only three resistance technologies
widely used for precision resistors in military and space
applications: Thin Film, Wirewound and Bulk Metal
®
Foil. Each has its own balance of characteristics and
costs that justify its selection in these applications. Thin
Films are most cost-efficient within their normal range of
characteristics but have the highest TCR, highest noise
and have the least stability of the three technologies.
Wirewounds have low noise, low TCR and a high level of
stability at moderate cost but also have high impedance
and slow signal response. Wirewounds can also have a
higher power density, but some stability is lost through
temperature cycling and load-life when made in smaller
configurations. Bulk Metal Foil resistors have the
lowest noise, lowest TCR, highest stability and highest
speed of any technology but may have a higher cost,
depending upon model. With Bulk Metal Foil resistors,
savvy designers often save overall by concentrating the
circuit stability in the Bulk Metal Foil resistors where
exceptional stability allows for use of less-costly active
devices—an option not available with other resistor
technologies because Bulk Metal Foil foil requires a
smaller total error budget through all cumulative resistor
life exposures. Also, Bulk Metal Foil often eliminates extra
circuitry added merely for the purpose of correcting the
limitations of other resistor components. FRSM Bulk
Metal Foil resistors, based on new generation technology
and improved production methods starting from
February 2011, offer designers the complete set of top
performance characteristics to simplify circuitry and lower
overall system costs by reducing the number of required
parts while assuring a better end product. The new series
of FRSM feature a long-term load-life stability within
0.0025% after 2000 hours and 0.005% after 10000 hours
under full rated power at +70°C, first time in the history of
all resistor technologies. In addition to their low absolute
TCR of almost zero TCR , the devices offer Power TCR
(“∆R due to self heating”) to ±5 ppm at rated power; tight
tolerance from 0.01% and thermal EMF of 0.05 μV/°C.
The causes of resistor drift are listed in Table 4 and
the allowances shown are for full scale exposure. The
designer may choose to use a percentage of full scale
stress factor if the equipment will never see the full
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2
scale conditions. For example, a laboratory instrument
that is expected to be permanently installed in an air-
conditioned laboratory does not need an end-of-life
allowance for excessive heat. There are other reasons for
tolerancing the resistors tighter than the initial calculation:
Measurement equipment accuracy is traditionally ten
times better than the expected accuracy of the devices
under test. These tighter tolerance applications require
a high precision resistor. Also, the drift of the resistor
without any stress factor considerations results in a shift
over time that must be considered. FRSMs have the least
amount of time shift. The manufacturer’s recommended
recalibration cycle is a factor in the saleability of the
product and the longer the cycle, the more acceptable the
product. Bulk Metal Foil resistors contribute significantly
to the longer calibration cycle.
Figure 1—Power Derating Curve
Rated Power (%)
100
75
50
25
0
- 75
- 55 °C
+ 70 °C
- 50
- 25
0
+ 25 + 50 + 75 + 100 + 125 + 150 + 175
Ambient Temperature (°C)
Lead (Pb)-free terminals
Tin/lead alloy terminals
Figure 2—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
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 Bulk Metal
®
Foil resistors.
Trimming process
removes this material
from shorting strip area
changing current path
and increasing
resistance
Foil shown in black, etched spaces in white
For any questions, contact
foil@vpgsensors.com
4220-EN
Rev 21-Aug-2020
FRSM Series
Figure 3—Typical Resistance/Temperature
Curve
(1)
+ 500
+ 400
+ 300
+ 200
+ 100
∆R
0
R
(ppm)
- 100
- 200
- 300
- 400
- 500
- 0.16 ppm/°C
Figure 4—Recommended Mounting
1. IR and vapor phase reflow are recommended.
2. Avoid the use of cleaning agents that attack epoxy
resins, which form part of the resistor construction.
3. Vacuum pick up is recommended for handling.
4. If the use of a soldering iron becomes necessary,
precautionary measures should be taken to avoid
any possible damage/overheating of the resistor.
0.05 ppm/°C
- 0.1 ppm/°C
0.1 ppm/°C
0.14 ppm/°C
0.2 ppm/°C
*
- 55
- 25
0
+ 25
+ 60 + 75 + 100 + 125
Ambient Temperature (°C) and TCR Chord Slopes for
Different Temperature Ranges
(1)
The TCR values for < 100 Ω are influenced by the
termination composition and result in deviation from this
curve.
* Recommendation: The solder fillet profile should be
such as to avoid running over the top metallization.
Table 2—Specifications
(1)
Chip
Size
0603
0805
1206
1506
2010
2512
(1)
Rated Power
at +70°C
(mW)
100
200
300
300
500
750
Max. Working
Voltage
(≤√P
×
R )
22 V
40 V
87 V
95 V
187 V
220 V
Resistance
Range
(Ω)
100 to 5k
5 to 8k
5 to 25k
5 to 30k
5 to 70k
5 to 125k
Typ. TCR and Spread,
–55°C to +125°C, +25°C Ref.
(ppm/°C)
Max. Weight
(mg)
4
6
±0.2 ±1.8 (≥100 Ω)
±0.2 ±2.8 (50 Ω to <100 Ω)
±0.2 ±3.8 (10 Ω to <50 Ω)
±0.2 ±7.8 (5 Ω to <10 Ω)
11
12
27
40
For tighter TCR and/or resistance values up to 150k, please contact Application Engineering.
Table 3—Dimensions
in inches (millimeters)
Date Code
(2)
(Year/Week)
T
D
Top View
L
W
Recommended Land Pattern
X
Footprint
Z
G
Chip Size
0603
0805
1206
1506
2010
2512
(1)
(2)
L
±0.005 (0.13)
0.063 (1.60)
0.080 (2.03)
0.126 (3.20)
0.150 (3.81)
0.198 (5.03)
0.249 (6.32)
W
±0.005 (0.13)
0.032 (0.81)
0.050 (1.27)
0.062 (1.57)
0.062 (1.57)
0.097 (2.46)
0.127 (3.23)
Thickness
Maximum
D
±0.005 (0.13)
0.011 (0.28)
0.015 (0.38)
0.020 (0.51)
0.020 (0.51)
0.025 (0.64)
0.032 (0.81)
Z
(1)
0.102 (2.59)
0.122 (3.10)
0.175 (4.45)
0.199 (5.05)
0.247 (6.27)
0.291 (7.39)
G
(1)
0.031 (0.78)
0.028 (0.71)
0.059 (1.50)
0.083 (2.11)
0.115 (2.92)
0.150 (3.81)
X
(1)
0.031(0.78)
0.050 (1.27)
0.071 (1.80)
0.071 (1.80)
0.103 (2.62)
0.127 (3.23)
0.025 (0.64)
Land Pattern Dimensions are per IPC-7351A.
The date code printing applies to all resistor sizes except for 0603.
For any questions, contact
foil@vpgsensors.com
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4220-EN
Rev 21-Aug-2020
FRSM Series
Table 4—Performances
Test or Conditions
Thermal Shock,
100 x (–65°C to +150°C), see Figure 6
Low Temperature Operation,
–65°C, 45 min at P
nom
Short Time Overload,
6.25 x Rated Power, 5 s
High Temperature Exposure,
+150°C, 100 h
Resistance to Soldering Heat,
+245°C for 5 s, +235°C for 30 s
Moisture Resistance
Load Life Stability,
+70°C for 2000 h at Rated Power, see Figure 8
Load Life Stability,
+70°C for 10,000 h at Rated Power
(1)
∆R
Limits of FRSM Series
Typical
Performance Limits
(1)
±0.005% (50 ppm)
±0.0025% (25 ppm)
±0.005% (50 ppm)
±0.0025% (25 ppm
±0.005% (50 ppm)
±0.003% (30 ppm)
±0.0025% (25 ppm)
±0.005% (50 ppm)
±0.01% (100 ppm)
±0.005% (50 ppm)
±0.01% (100 ppm)
±0.005% (50 ppm)
±0.01% (100 ppm)
±0.01% (100 ppm)
±0.005% (50ppm
±0.04% (400ppm)
As shown +0.01
Ω
to allow for measurement errors at low values.
PULSE TEST
Test Description and Results
All parts baked at +125°C for 1 hr and allowed to cool at room
temperature for 1 hr, prior to testing. By using an electrolytic
0.01 μF capacitor charged to 1000 VDC, a single pulse was
performed on 20 units of 1206, for each value: 100Ω, 1 KΩ and
10 KΩ of surface mount Bulk Metal
®
Foil resistor and thin film
resistor. The unit was allowed time to cool down, after which
the resistance measurement was taken and displayed in ppm
deviation from the initial reading.
Figure 6—Thermal Shock Test
Test per MIL PRF 55342 4.8.3 Mil STD 202, Method 107
Test Conditions: 100 X (-65°C to +150°C), n=10
100
80
60
R (ppm)
40
20
Figure 5—Pulse Test Description
0
-20
0805
1K
0805
8K
1206
1K
1206
25K
2512
1K
2512
75K
ELECTROSTATIC DISCHARGE (ESD)
µF
Rx
ESD can be categorized into three types of damages:
Parametric Failure
occurs when the ESD event alters
one or more device parameters (resistance in the case of
resistors), causing it to shift from its required tolerance.
This failure does not directly pertain to functionality; thus
a parametric failure may be present while the device is still
functional.
Catastrophic Damage
occurs when the ESD event
causes the device to immediately stop functioning. This
may occur after one or a number of ESD events with
diverse causes, such as human body discharge or the
mere presence of an electrostatic field.
Latent Damage
occurs when the ESD event causes
moderate damage to the device, which is not noticeable,
as the device appears to be functioning correctly.
However, the load life of the device has been dramatically
reduced, and further degradation caused by operating
stresses may cause the device to fail during service.
Latent damage is the source for greatest concern,
because it is very difficult to detect by re-measurement
or by visual inspection, since damage may have occurred
under the external coating.
Table 5—Pulse Test Results
Value
100R
1k
10k
Voltage
1000
VDC
T = RC
1 μsec
10 μsec
100 μsec
AVERAGE DEVIATION (%)
Bulk Metal Foil
Thin Film
Open
<0.001
>35
>0.008
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4
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4220-EN
Rev 21-Aug-2020
FRSM Series
Test Description and Results
By using a electrolytic 500 pF capacitor charged up to 4500 V,
pulses were performed on 10 units of 1206, 10 kΩ of three
different Surface Mount Chip Resistors technologies, with an
initial voltage spike of 2500 V (Figure 7). The unit was allowed
time to cool down, after which the resistance measurement was
taken and displayed in ppm deviation from the initial reading.
Readings were then taken in 500 V increments up to 4500 V.
POWER COEFFICIENT OF RESISTANCE
(PCR)
In precision resistors with low TCR, the self heating (Joule
effect) causes the resistor not to perform strictly to its
TCR specifications. This inaccuracy will result in an error
at the end in the resistance value under applied power.
Vishay Foil Resistors introduced a new concept of Power
Coefficient of Resistance (PCR) along with a new Z-Foil
technology which leads to reduction of the sensitivity of
precision resistor to ambient temperature variations and
changes of applied power.
Figure 9 represents PCR behavior of three different
resistor technologies under applied power.
Figure 7—ESD Test Description
2500 V to 4500 V
1 MΩ
Figure 9—Behavior of Three Different
Resistor Technologies Under Applied Power
(Power Coefficient Test)
500 pF
+100 ppm
0.1
0.2
0.3
0.4
0.5
Thick Film
Surface
Mount Chip
Thin Film
Surface
Mount Chip
Rx
R
-------
(ppm)
-
R
0 ppm
Z-Foil
Surface
Mount Chip
DMM
–100 ppm
Table 6—ESD Test Results
Volts
2500
3000
3500
4000
4500
Thick Film
–2.7
–4.2
–6.2
–7.4
–8.6
∆R (%)
Thin Film
97
366
>5000
>5000
Open
Bulk Metal Foil
Applied power, (W)
Note: Size 1206, value: 1K
Figure 10—Current Path in a Resistive Alloy
<0.005
Figure 8—Load Life Test for 2000 Hrs @
+70°C at Rated Power
100
80
60
40
20
0
-20 0
-40
-60
-80
-100
250
500
750
1000 1250 1500 1750 2000 2250
0805-1K
0805-8K
1206-1K
1206-25K
2512-75K
2512-125K
R (ppm)
Noise generation is minimal when current
flow is through multiple paths as exists in
Bulk Metal Foil resistive alloy.
Time (hrs)
4220-EN
Rev 21-Aug-2020
For any questions, contact
foil@vpgsensors.com
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5
