Conductor / Resistor Films by Characteristics 2017-02-14T21:12:38+00:00

Conductor / Resistor Films (by characteristics)

A basic understanding of thin lm resistor design is required if you want to integrate sheet resistors into your circuit. Thin lm sheet resistors are typically fabricated by sputtering a lm of Tantalum-Nitride (TaN) under the conductor layer and then selectively etching the resistor elements. TaN resistors are very stable and reliable after they are passivated at high temperatures. Nichrome (NiCr) resistors are used in specialty applications where a low TCR (Temperature Coef cient of Resistance) is required.

Commonly Used Conductor/Resistor Films

View by Characteristics

WTi/Au
Typical Applications Devices processed at high temperatures, such as Au/Ge eutectic bonding temps
Advantages Film withstands excursions to 450°C
Disadvantages Barrier layer recommended for eutectics
Temperature Guidelines 450°C for 30 minutes
Pb/Sn, Au/Sn Solderability Possible diffusion/enrichment
Allowable Die Attach Methods · Epoxies
· Au/Ge eutectic
· Au/Si eutectic
· Au/Sn solder
· Pb/In eutectic
Typical TCR n/a
Front Side Metal · Sputtered WTi 300-500Å
· Sputtered Au 20-300µ”
Back Side Metal Same as front side
WTi/Ni/Au
Typical Applications Devices processed at higher temperatures requiring a solderable film
Advantages Film withstands brief excursions to 325°C
Disadvantages Wire bonding problems may be possible due to Ni-Au diffusion when devices processed > 300°C
Temperature Guidelines 300°C for 120 minutes
Pb/Sn, Au/Sn Solderability Good
Allowable Die Attach Methods · Pb/Sn solder
· Au/Sn solder
· Epoxies
· Pb/In eutectic
Typical TCR n/a
Front Side Metal · Sputtered WTi 300-500Å
· Sputtered Ni 2,000-5,000Å
· Sputtered Au 20-300µ”
Back Side Metal Same as front side
WTi/Au/Cu/Ni/Au
Typical Applications High conductivity film allowing for wire bonding and/or soldering after high temp. processing
Advantages · High conductivity film
· Pb/Sn & Au/Sn solderable
Disadvantages Wire bonding problems may be possible due to Ni-Au diffusion when devices processed > 300°C
Temperature Guidelines 300°C for 120 minutes
Pb/Sn, Au/Sn Solderability Good
Allowable Die Attach Methods · Pb/Sn solder
· Au/Sn eutectic
· Epoxies
· Pb/In eutectic
Typical TCR n/a
Front Side Metal · Sputtered WTi 300-500Å
· Sputtered Cu 40µ”
· Electroplated Cu 40-2000µ”
· Electroplated Ni 50-150µ”
· Electroplated Au 50-250µ”
Back Side Metal Same as front side
TaN/WTi/Au
Typical Applications Devices processed at high temperatures, such as Au/Ge eutectic bonding temps
Advantages · Film withstands excursions to 450°C
· Passivated TaN films offer good humidity resistance
Disadvantages · Not Pb/Sn or Au/Sn Solderable
· Should be fully sputtered in order to provide blister free films
Temperature Guidelines Stabilize resistors at 425°C for 30.120 minutes
Pb/Sn, Au/Sn Solderability Poor
Allowable Die Attach Methods · Epoxies
· Au/Ge eutectic
· Au/Si eutectic
· Au/Sn eutectic
· Pb/In eutectic
Typical TCR -100 ± 50 ppm/°C
Front Side Metal · Sputter 10-150 Ω/sq. TaN
· Sputtered WTi 300-500Å
· Sputtered Au 20-300µ”
Back Side Metal Same as front side without the TaN layer
TaN/WTi/Ni/Au
Typical Applications Devices processed at higher temperatures requiring a solderable film
Advantages · Pb/Sn & Au/Sn solderable
· Passivated TaN films offer good humidity resistance
Disadvantages Wire bonding problems may be possible due to Ni-Au diffusion when devices processed > 300°C
Temperature Guidelines Stabilize resistors at 325°C for 60 minutes
Pb/Sn, Au/Sn Solderability Good
Allowable Die Attach Methods · Pb/Sn solder
· Au/Sn solder
· Epoxies
· Pb/In eutectic
Typical TCR -100 ± 50 ppm/°C
Front Side Metal · Sputter 10-200 Ω/sq. TaN
· Sputtered WTi 300-500Å
· Sputtered Ni 2,000-5,000Å
· Sputtered Au 20-300µ”
Back Side Metal Same as front side without the TaN layer
NiCr/Ni/Au
Typical Applications Designs requiring precision resistors with low TCR’s
Advantages Low TCR’s (0 ± 50 ppm/°C)
· Pb/Sn & Au/Sn solderable
Disadvantages Wire bonding problems may be possible due to Ni-Au diffusion when devices processed > 300°C
Temperature Guidelines Stabilize resistors at 325°C for 60 minutes
Pb/Sn, Au/Sn Solderability Good
Allowable Die Attach Methods · Pb/Sn solder
· Au/Sn solder
· Epoxies
· Pb/In eutectic
Typical TCR 0 ± 50 ppm/°C
Front Side Metal · Sputter 50-200 Ω/sq. NiCr
· Sputtered Ni 2,000-5,000Å
· Sputtered Au 20-300µ”
Back Side Metal Same as front side (NiCr for adhesion only)