WIRE BONDING GUIDELINES

Wire Bonding and Ribbon Bonding

  • Gold Ball Wire Bonding (Thermosonic @ +150°C).
  • Gold Wedge Wire Bonding (Thermosonic @ +150°C).
  • Aluminum Wedge Wire Bonding (Ultrasonic @ +25°C).
  • Ribbon Bonding for high frequency applications 20-100 GHz.

PCB Gold Plating for Wire Bonding (Rigid, Flex and Rigid-Flex)

  • ENEPIG, IPC-4556: Electroless Ni/ Electroless Pd/ Immersion Au.
IPC-4556 ENEPIG SMT and Gold Wire Bonding
3rd level Gold ≥0.1 um (≥ 4 uinches) Immersion Gold
2nd level Palladium 0.05 – 0.30 um (2 – 12 uinches) Electroless Palladium
1st level Nickel 3-6 um (118 – 236 uinches) Electroless Nickel
  • ENIG, IPC-4552: Electroless Ni/ Immersion Au.
IPC-4552 ENIG SMT and Aluminum Wire Bonding
2nd level Gold ≥0.05 um (≥ 2 uinches) Immersion Gold
1st level Nickel 3-6 um (118 – 236 uinches) Electroless Nickel

Wire Bond Pad size on Rigid, Flex or Rigid-Flex PCB

Description Design Guideline
PCB Bond Pad Size (Preferred) ≥ 100 x 300um (4x12mil)
PCB Bond Pad Size (Minimum) ≥ 100 x 250um (4x10mil)
PCB Pad Pitch ≥200um (8mil)
PCB over-etching (Maximum) ≤10% (min. bond pad width 90um)
Solder mask clearance on bond pad ≥ 200 um (8mil)
Solder mask opening on bond pad BPL + 400 um and BPW + 400 um
Solder mask thickness LPI ≤ +/-25um; LDI ≤ +/-15um
Solder mask alignment tolerance LPI ≤ +/-50um; LDI ≤ +/-30um

Gold Ball or Gold Wedge Wire Bonding: (ENEPIG)

  • Gold Ball or Gold Wedge Wire Bonding, Thermosonic @ +150°C.
  • 20um (0.8mil), 25um (1.0mil) and 32um (1.25mil) wire diameter standard.
Wire Diameter Size um (mil) Wire Length (mm) IC Bond Pad
um(min)
IC Pad Pitch
um(min)
Staggered Pitch um(min)
18um (0.7mil) * ≥0.3≤2.7mm ≥35um ≥45um 23/46um
20um (0.8mil) ≥0.3≤3.0mm ≥45um ≥55um 28/56um
25um (1.0mil) ≥0.3≤3.75mm ≥55um ≥65um 33/66um
32um (1.25mil) ≥0.4≤4.8mm ≥70um ≥90um 45/90um
38um (1.5mil) * ≥0.5≤5.7mm ≥90um ≥110um 55/110um

Aluminum Wedge Wire Bonding: (ENIG)

  • Aluminum Wedge Wire Bonding, Ultrasonic @ +25°C.
  • 20um (0.8mil), 25um (1.0mil) and 32um (1.25mil) wire diameter standard.
Wire Diameter Size um (mil) Wire Length (mm) IC Bond Pad um(min) IC Pad Pitch
um(min)
Staggered
Pitch um(min)
18um (0.7mil) * ≥0.3≤3.6mm ≥45um ≥55um 28/56um
20um (0.8mil) ≥0.3≤4.0mm ≥55um ≥65um 33/66um
25um (1.0mil) ≥0.3≤5.0mm ≥65um ≥75um 38/76um
32um (1.25mil) ≥0.4≤6.4mm ≥80um ≥100um 50/100um
38um (1.5mil) * ≥0.5≤7.6mm ≥100um ≥120um 60/120um

Wire Bond Pull Test (DPT), per MIL-STD-883 TM2011

Destructive Bond Pull Test Wire Size  um (mil) Gold min.gm force Aluminum min.gm force
Double Bond 18um (0.7mil) ≥2.0 ≥1.5
Double Bond 20um (0.8mil) ≥2.5 ≥2.0
Double Bond 25um (1.0mil) ≥3.0 ≥2.5
Double Bond 32um (1.25mil) ≥4.0 ≥3.0
Double Bond 38um (1.5mil) ≥5.0 ≥4.0

Wire Bond Deformation, per MIL-STD-883 TM2017

Description MIL-STD-883, TM2017
Bond Visual Inspection 30x to 60x magnification
Inspect Ball Bond Wedge Bond
Bonds on Die, PCB or Package

Gold Ball
Ball (MBD): 2x to 3x
wire diameter

Gold Crescent
Bond Width:  1.2x to 3x Bond Length:0.5x to 3x
(Tailless Bond)

Aluminum Wedge (Foot)
Bond Width:  1.2x to 3x wire diameter
Bond Length:1.5x to 3x wire diameter
Bond Tail: ≤2x wire diameter
Gold Wedge (Foot)
Bond Width:  1.5x to 3x wire diameter
Bond Length:1.5x to 3x wire diameter
Bond Tail: ≤2x wire diameter

Wire Bond Electrical Resistance and Burn-out Current

Wire Dia. um (mil) Gold 4N Al, 1%Si Gold 4N Al, 1%Si
Resistance Ω(mm²)/m 0.0222 0.0278 Length ≥1mm Length ≥1mm
DC Resistance Ohm/m Burn-out current, Amps
18um (0.7mil) 88.03Ω/m 104.33Ω/m 0.38A 0.21A
20um (0.8mil) 71.30Ω/m 84.50Ω/m 0.46A 0.30A
25um (1.0mil) 45.63Ω/m 54.08Ω/m 0.63A 0.47A
32um(1.25mil) 27.85Ω/m 33.01Ω/m 0.91A 0.68A
38um (1.5mil) 19.75Ω/m 23.41Ω/m 1.17A 0.88A