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32

The temperature rise graph

data was obtained by a

selection of test substrate

size and trace width for

each resistor size to limit

operating temperatures to

safe values.

The operating temperature

safe rises are either 100°C

substrate temperature rise

or 180°C package hot spot

temperature rise at 25°C

ambient.

FR4: 0.062 in. thick; 0.062

in. traces

Alumina: 0.040 in. thick;

0.010 in. traces

Molding material rated at

205°C continuous.

100%

200%

300%

200

180

160

140

120

100

80

60

40

20

Percent Rated power

Alumina

Solder joint

FR4

Package limit hot spot temperature rise

100

Ambient Temperature, ϒC

60

20

0

80

40

25

50

100

150

75

0

125

Derating

0.02

500

400

300

200

100

Ohms

0.04 0.06 0.08 0.10

Typical TCR for

less than 0.1

SMD

resistors (PPM/°C)

TCR

Surface Mount Power

Temp. cycle

Load Life

Immersion

(-55°C to 125°C, (1000 hours

(260°C for

Momentary

Construction

1000 cycles)

at 25°C)

10 sec.)

Overload

RC

Carbon/Ceramic Comp.

±4.0%+.05Ω ±10.0%+.05Ω ±3.0%+.05Ω 6.3x rated power for 5 sec.

RF

Metal Film

±0.5%+.05Ω ±0.5%+.05Ω ±0.1%+.05Ω 2x rated power for 0.1 sec.

RW

Wirewound

±0.5%+.05Ω ±3.0%+.05Ω ±0.1%+.05Ω 5x rated power for 5 sec.

RP

Power Film

±3.0%+.05Ω ±5.0%+.05Ω ±0.5%+.05Ω 2x rated power for 0.1 sec.

RN

Wirewound, Non-inductive ±0.5%+.05Ω ±3.0%+.05Ω ±0.1%+.05Ω 5x rated power for 5 sec.

ALL models:

Leaching

(260°C Solder immersion, 60 sec.).......................

No visible leaching

Thermal Shock

(Units at -55°C, then rated power applied).. No mechanical damage

Flammability

......................................................................... UL Material rating, UL94V0

P er FO r M a NC e data

Recommended Solder Profile

300

Time (sec.)

Preheating

120 sec.

Soldering

Cooling

200

50

50

0

100

150

250

200

0

250

100

150

60 sec.

10 sec.

Preheating:

145°C ±15°, max. 120 sec.

Soldering:

min. 220°C, max. 60 sec.

Max. Temp.:

260°C ±5°, 10 sec.