Precision shunt resistors use gold-plating for conductive-adhesive mounts

May 13, 2014 // By Graham Prophet
PMH-D and PLU precision performance foil resistors from Isabellenhütte are gold-plated bondable parts for mounting with conductive adhesive.

Produced using the Isa-Plan process they comprise three layers of manganin foil, copper substrate and an adhesive with good thermal conductivity (ceramic filled), pressure bonded. This highly temperature-resistant bonded combination of substrate and resistant foil ensures optimal dissipation of heat. A small increase in the temperature of the component has a positive effect on stability and long-term drift, suiting the resistors to applications in the automotive sector in which there are high requirements in terms of temperature and load. They meet the international AEC-Q200 specifications. The PMH-D and PLU are also suitable for industrial applications such as frequency converters and power modules with DCB ceramic substrates.

The PMH-D (6.7 x 3.4 x 0.7 mm) and the PLU (10.4 x 6.4 x 0.6 mm) are designed for hybrid mounting with bonding technology. The bonding pads and the back side of the component are plated with a 0.1 μm layer of gold, for both soldering and mounting with conductive adhesive. The result is an ideal thermal coupling that makes best use of the available component surface. The resistors are designed to handle a constant load of up to 5W at 150°C and a constant current of up to 50A (PMH-D / size 2512) and 70A (PLU / size 3924). The PMH-D is currently available as a 2-mOhm resistor and the PLU as a 1-mOhm resistor. Both resistors are designed as four-wire measurement resistors (Kelvin connection).

Technical details, PLU:

Resistance 1 mOhm

Tolerance 5% (depending on the bonding position)

Temperature coefficient (20 - 60 °C) < 50 ppm/K (depending on the bonding position)

Temperature range -55 to +170°C

Load capacity 5W

Inner thermal resistance < 4 K/W

Inductance < 10 nH

Dielectric strength 100 VAC

Stability (nominal load) < 0.5% (TK = 120°C)

Deviation after 2,000 hrs < 1.0% (TK = 150°C)

TK = contact point temperature

Technical details, PMH-D:

Resistance 2 mOhm

Tolerance 5% (depending on the bonding position)

Temperature coefficient (20-60 °C) < 50 ppm/K (depending on the bonding position)

Temperature range -55