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VPG – Bulk Metal Foil resistors perform in the most demanding applications
Published Aug 9 2012 

VPG – Bulk Metal Foil resistors perform in the most demanding applications

Vishay Precision Group’s (VPG) VFR brand’s RCK and S series high-precision
Bulk Metal Foil resistors and HTHA series ultra-high-precision Bulk Metal
Z1-Foil hybrid chip resistors satisfy the most demanding application needs.

The RCK and S series resistors represent the latest in a long series of
advancements that began with a breakthrough packaging concept developed by
foil technology inventor Dr. Felix Zandman. In 1962, Dr. Zandman -
world-renowned for his work in stress analysis – took his ideas for uniquely
isolated strain gages and applied them to the electronics industry. The
result was the most precise and stable resistor ever developed. The first
high-precision foil resistor introduced to the market was the S102, the
archetype of the current S102C and RCK devices. The S102 was also the first
resistor with a flat rectangular case. This unusual configuration was at
first questioned by the market. However, once Dr. Zandman demonstrated the
board efficiency achieved by stacking multiple square resistors
side-by-side, the square configuration was readily accepted and has since
become the standard in many applications.

RCK and S series resistors feature an advanced design and manufacturing
process that results in improved power dissipation, load life stability of
0.005%, fast thermal stabilization of <1s (nominal value achieved within
10ppm of steady state value), low thermal EMF of 0.05μV/C, resistance
tolerance to ±0.005% (50ppm), and increased performance in high-moisture,
high-temperature, and high-pulse applications. The resistors are built to
handle unconventional environmental conditions with minimal drift, making
them suitable for any analog circuit where stability is the main concern.

HTHA resistors are part of the fourth generation of Foil technology that was
developed by the VFR R&D team guided by Dr. Zandman before he passed away in
June 2010. The HTHA series was launched to celebrate VFR’s 50-year
anniversary. The devices were designed for demanding high-temperature
applications to +240C, including geothermal measuring equipment, turbine
engine control, and environmental test chambers in military, industrial,
automotive, and down-hole drilling systems. For these applications, the
resistors feature exceptional load-life stability to ±0.05% at +220C for
2,000 hours at working power, and long-term stability to ±0.05% at +240C for
2,000 hours (no power). The devices can be connected using aluminium wire
bonding or surface-mounted by electrical conductive epoxy or reflow
soldering. The resistors are available in a gold-wire bonding version – the
HTHG.