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/Pd/Au
Typical Applications

Devices processed at higher temperatures requiring a solderable film

Advantages

Film withstands brief excursions to 325°C but Ni-Au diffusion problems avoided

Disadvantages

Pd slightly more costly than Ni

Temperature Guidelines 300°C for 120 minutes
SAC, Au/Sn Solderability Good
Allowable Die Attach Methods · Pb/Sn solder
· Au/Sn solder
· SAC
· Epoxies
Typical TCR n/a
Front Side Metal · Sputtered WTi 300-500Å
· Sputtered Pd 2,000-5,000Å
· Sputtered Au 20-400µ"
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)
 
 
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