FRSH Series (0603, 0805, 1206, 1506, 2010, 2512) (Z1-Foil)

Vishay Foil Resistors

www.vishayfoilresistors.com

Document Number: 63211

2

Revision: 20-Mar-12

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

processing, such as repetitive short term power overloads, to

assure reliable service through the unpredictable stresses of

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.

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.

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

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