PRELIMINARY
FRSH Series (0603, 0805, 1206, 1506, 2010, 2512) (Z1-Foil)
Vishay Foil Resistors
www.vishayfoilresistors.com For any questions, contact: foil@vishaypg.com Document Number: 63211
2Revision: 21-Dec-11
HIGH TEMPERATURE PRODUCTS
Resistors are the passive building blocks of an electrical
circuit. They may be used for dropping the voltage, buffering
the surge when the circuit is turned on, providing feedback in
a monitoring loop, sensing current flow, etc.When the
application requires stability over time and load, initial
accuracy, minimal change with temperature for more than
200 °C, resistance to moisture and a number of other
characteristics that will be described below, only the new
generation of Vishay Foil Resistors have the attributes
needed for such application. Over the past few months, there
has been considerable growth in the demand for precise,
stable and reliable resistors that can operate in harsh
environments and especially at high temperatures to 220 °C.
Many analog circuits for industrial, military, aerospace,
medical, down-hole, oil well and automotive applications
require passive components such as resistors to have a
minimal drift from their initial values when operating above +
175 °C and in humid environments. In these applications, the
most important factor is the temperature dependence and
the end of life tolerance (which is part of the stability) and to
a lesser extent, the initial tolerance.
The new Vishay Foil resistors provide stabilities well under
the maximum allowable drift required by customers’
specifications through thousands of hours of operation under
harsh conditions, such as the extreme temperatures and
radiation-rich environments of down-hole oil-well logging
applications, in the frigid arctic, under the sea or in deep
space. All Bulk Metal® Foil resistors receive stabilization
processing, such as repetitive short term power overloads, to
assure reliable service through the unpredictable stresses of
extreme operation. Compared to Bulk Metal® Foil, thick and
thin film resistor elements are produced with a
non-controllable material. Heat or mechanical stresses on
the resistive elements cause the particles forming the film to
expand. However, after these stresses are alleviated, the
particles in the film matrix do not return to the exact original
position. That degenerates their overall stability.
Vishay Foil Resistors’ Ultra High Precision Bulk Metal® Foil
technology includes many types of resistors with a variety of
standard configurations that can withstand unconventional
environmental conditions above and below the earth’s
surface using special post manufacturing operations
specially developed for this purpose. The stability of a
resistor depends primarily on its history of exposures to high
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 of Resistance, 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 that need to operate in an
environment with temperatures above + 175 °C, these
effects must be taken into account to achieve high stability
with changes in load (Joule Effect) and ambient temperature.
The Bulk Metal® Foil Resistors’ new Z1-Foil technology
provides an order of magnitude reduction in the Bulk Metal®
Foil element’s sensitivity to temperature changes — both
external and internal – with emphasis on long term stability in
high temperature environments.
In order to take full advantage of the low TCR and long term
stability improvement, it is necessary to take into account the
differences in the resistor’s response to each of the
above-mentioned effects. As described below, new products
have been developed to successfully deal with these factors.
For high temperature applications where stability and total
error budget is the main concern, the new generation of
Vishay Foil resistors offers the best resilience against time at
elevated temperature.
The new Vishay Foil technology allows us to produce
customer-oriented products designed to satisfy unique and
specific technical requirements. In addition to the special
chip stabilization under extreme environment conditions in
the production line, we offer additional specially oriented post
manufacturing operations (PMO) for high temperature
applications that require an even higher degree of reliability
and stability.
Electrostatic Discharge (ESD) is another potential problem
that can cause unpredictable failure in high temperature
applications that increase the sensitivity of the resistors to
ESD.
ESD damage to electronic devices can occur at any point in
the device’s life cycle, from manufacturing to field service. A
resistor that is exposed to an ESD event may fail immediately
or may experience a latent defect. With latent defects,
premature failure can occur after the resistor is already
functioning in the finished product after an unpredictable
length of service. Bulk Metal® Foil resistors are capable of
withstanding electrostatic discharges at least to 25 kV without
degradation.
VFR’s Application Engineering department is always
available to assist with any special requirements you might
have. If you are not sure which resistor best suits your needs,
please do not hesitate to contact them for more information:
Foil@vishaypg.com