303261, 303262, 303263, 303264, 303265, 303266
Vishay Foil Resistors
Ultra High-Precision Wrap-Around Chip Resistors,
UltraHigh-PrecisionWrap-AroundChipResistors,
FRSMZ-1FoilT
echnologyConfiguration
FRSM Z-1 Foil Technology Configuration
Screen/Test Flow in Compliance with
EEE-INST-002 (Tables 2A and 3A, Film/Foil, Level 1) and MIL-PRF-55342
FEATURES
• Temperature coefficient of resistance (TCR)(see table 1
and fig. 3):
±0.05 ppm/°C nominal (0°C to +60°C, +25°C ref)
±0.2 ppm/°C nominal (–55°C to +125°C, +25°C ref.)
• Resistance tolerance: to ±0.02%
• Power coefficient “∆R due to self heating”: 5 ppm at
rated power
• Power rating: to 400 mW at +70°C (see table 2)
•
Load life stability: ±0.02% after 2,000 hrs at 70°C at
rated power.
• Resistance range: 10 Ω to 75 kΩ (for higher and lower
values, please contact us)
• 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)
• Thermal stabilization time: <1 s (within 10 ppm of steady
state value)
• Electrostatic discharge (ESD): at least to 25 kV
• Short time overload: ≤0.005%
• 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
• Non-inductive: <0.08 μH
• Non-hot spot design
• Terminal finishes available: tin/lead alloy
• Matched sets are available on request
• Prototype quantities available in just 5 working days or
sooner. For more information, please contact us.
• For higher temperature application up to +240°C and for
better performances, please contact us.
• Adding “U” to the model number (example: 303261U).
These units have all of the Table 2A (page 5) 100% tests
performed, with no destructive qualification testing
required (Table 3A, page 6). For more information,
please contact
foil@vishaypg.com.
Top View
INTRODUCTION
The 303261 through 303266 series, tested per
EEE-INST-002 and MIL-PRF-55342, is based on the new
generation Z-1 technology of the Bulk Metal
®
precision foil
resistor elements by Vishay Precision Group (VPG), which
makes these resistors virtually insensitive to destabilizing
factors. Their element, based on the new Z-1 Foil, 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 +150°C.
Resistance patterns are photo-etched to permit trimming
of resistance values to very tight tolerances.
The 303261 through 303266 series has a full wraparound
termination which ensures reliable handling during the
manufacturing process, as well as providing stability
during multiple thermal cycles.
Our application engineering department is available to
advise and make recommendations. For non-standard
technical requirements and special applications, please
contact us at foil@vishaypg.com.
RELATED DOCUMENT
From our Technical Library, please see
Reading Between
the Lines in Resistor Datasheets.
RELATED VIDEO
From our Video Library, refer to
Z-Foil vs Thin Film
Resistors with Intersil Instrumentation Amplifier
(Demo
Video).
Document No.: 63253
Revision: 19-Feb-2014
For questions, contact
foil@vishaypg.com
www.vishayfoilresistors.com
1
303261, 303262, 303263, 303264, 303265, 303266
Vishay Foil Resistors
FIGURE 1—POWER DERATING CURVE
Percent of Rated Power
100
75
50
25
0
–75
–55°C
+70°C
TABLE 1—BEST TOLERANCE AND TCR VS.
RESISTANCE VALUE
(–55°C to +125°C, +25°C Ref. nominal plus
spread)
Resistance Value
Ω
250 to 75k
100 to 250
50 to 100
Tolerance (%)
±0.02%
±0.05%
±0.1%
±0.25%
±0.5%
Maximum TCR
(ppm/°C)
±3
±3
±4
±5
±5
–50
–25
0
+25
+50
+75
+100 +125 +150 +175
25 to 50
10 to 25
Ambient Temperature (°C)
ABOUT 303261—303266 SERIES
Several factors need to be considered when choosing a
resistor for applications that require long-term stability,
including TCR (influence of 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, uncertain
long-term stability, 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 and a thermal lag of 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 foil resistors where exceptional
stability allows for use of less-costly active devices—an
option not available with other resistor technologies
because foil requires a smaller total error budget through
all cumulative resistor life exposures. Also, 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
www.vishayfoilresistors.com
2
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 FRSM series (made and tested in accordance with
EEE-INST-002) features a long-term load-life stability
within 0.0025% after 2000 hours and full rated power at
+70°C. 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
0.02% and thermal EMF of 0.05 μV/°C. Current design
practice has been to over-specify resistors to allow for
expected tolerance degradation during service. There is
also a trend to move to commercial-off-the-shelf (COTS)
parts. Vishay Precision Group offers a new approach
with lower prices to bring Foil resistors within the reach
of designers whose end-of-life tolerance target is 0.05%
(total end of life cumulative deviation from nominal) or less
with COTS resistors having all the inherent features for
long term reliability.
While other resistor technologies can take several
seconds or even minutes to achieve a steady state
thermal stabilization (thermal lag), Vishay Foil resistors
feature an almost instantaneous thermal stabilization
time and a nearly immeasurable 1 ns rise time, effectively
with no ringing. The stress levels of each application are
different so the designer must make an estimation of what
they might be and assign a stress factor to each one. The
stress may normally be low but for these purposes, we
must assure that the installed precision resistor is capable
of reliability withstanding all potential stresses. For
example, if the resistor is installed in a piece of equipment
that is expected to go out into an oil field in the back of
a pickup truck, shock and vibration and heat from the
sun are obvious factors. The specific 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 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
Document No.: 63253
Revision: 19-Feb-2014
For questions, contact
foil@vishaypg.com
303261, 303262, 303263, 303264, 303265, 303266
Vishay Foil Resistors
traditionally ten times better than the expected accuracy
of the devices under test. So, these tighter tolerance
applications require a Foil 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. Foil resistors contribute
significantly to the longer calibration cycle.
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
Trimming Process
Removes this Material
from Shorting Strip Area
Changing Current Path
and Increasing
Resistance
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 resistors.
Foil shown in black, etched spaces in white
FIGURE 3—NOMINAL
RESISTANCE/TEMPERATURE CURVE
+400
+300
∆R
(ppm)
R
+500
TABLE 2—SPECIFICATIONS
(1)
Model
(Chip Size)
303261 (0603)
303262 (0805)
Rated
Power
at +70°C
(mW)
50
100
150
200
300
400
Max.
Working
Voltage
(≤√P
×
R )
14 V
22 V
46 V
57 V
102 V
173 V
Resistance
Range
(Ω)
100 to 2k
10 to 5k
10 to 14k
10 to 16k
10 to 35k
10 to 75k
Max.
Weight
(mg)
4
6
11
12
27
40
+200
+100
–100
–200
–400
–300
–500
0
0.05 ppm/°C
–0.1 ppm/°C
–0.16 ppm/°C
0.1 ppm/°C
0.14 ppm/°C
0.2 ppm/°C
303263 (1206)
303264 (1506)
303265 (2010)
303266 (2512)
+100
+125
–55
–25
0
+25
+60
+75
Ambient Temperature (°C) and TCR Chord Slopes for
Different Temperature Ranges
Notes
(1)
For tighter performances and non-standard values up to 125k, please contact VPG application engineering at foil@vishaypg.com.
Document No.: 63253
Revision: 19-Feb-2014
For questions, contact
foil@vishaypg.com
www.vishayfoilresistors.com
3
303261, 303262, 303263, 303264, 303265, 303266
Vishay Foil Resistors
TABLE 3—DIMENSIONS
in Inches (Millimeters)
Top View
L
T
D
Chip Size
0603
0805
1206
1506
2010
2512
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)
W
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)
0.025 (0.64)
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 7
Note
(3)
As shown +0.01
Ω
to allow for measurement errors at low values.
∆R
Limits of FRSM Series
Typical
Maximum
(3)
±0.005% (50 ppm)
±0.005% (50 ppm)
±0.005% (50 ppm)
±0.005% (50 ppm)
±0.005% (50 ppm)
±0.003% (30 ppm)
0.0025% (25 ppm)
±0.01% (100 ppm)
±0.015% (150 ppm)
±0.02% (200 ppm)
±0.015% (150 ppm)
±0.02% (200 ppm)
±0.025% (250 ppm)
±0.02% (200 ppm)
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.
*
Recommendation: The solder fillet profile should be such as to avoid running over the
top metallization.
*
www.vishayfoilresistors.com
4
For questions, contact
foil@vishaypg.com
Document No.: 63253
Revision: 19-Feb-2014
303261, 303262, 303263, 303264, 303265, 303266
Vishay Foil Resistors
TABLE 5—EEE-INST-002 (TABLE 2A FILM/FOIL, LEVEL 1) 100% TESTS/INSPECTIONS
Test or Inspection
Pre-cap Visual Inspection
RC Record
Thermal Shock
Power Conditioning
RC Record
Final Inspection
Visual Inspection
Mechanical Inspection
Result
Performed in production flow prior overcoating
In tolerance
25 x (–65°C to +150°C)
70°C, 100 h, 1.5 rated power—not to exceed max. voltage
In tolerance ∆R = 0.05% for thermal shock and conditioning combined
5% PDA on ∆R only, 10% PDA on “Out of Final Tolerance”
Materials, design, etc.
Physical dimensions, sample size: 3 units, zero failure
ELECTROSTATIC DISCHARGE (ESD)
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.
FIGURE 5—ESD TEST DESCRIPTION AND RESULTS
2500 V to 4500 V
1 MΩ
500 pF
By using an electrolytic 500 pF capacitor charged up to 4500V,
pulses were performed on 10 units of 1206, 10 kΩ of three
different Surface Mount Chip Resistors technologies, with an
initial voltage spike of 2500V. 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 500V increments up to 4500V.
Rx
Volts
2500
3000
3500
4000
4500
DMM
Thick Film
–2.7
–4.2
–6.2
–7.4
–8.6
∆R (%)
Thin Film
97
366
>5000
>5000
Open
Foil
<0.005
Document No.: 63253
Revision: 19-Feb-2014
For questions, contact
foil@vishaypg.com
www.vishayfoilresistors.com
5
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