Microelectronics

Design & Assembly Advanced Microelectronics

DIE-ATTACH, FLIP CHIP and MULTI-CHIP

  1. Die Attach: Epoxy Die Attach
  2. Auto Die Pick and Plate
  3. Auto Die Attach
  4. Manual Die Attach
  5. Die Attach Pad size vs. Die size
  6. Advanced Flip Chip Assembly

WIRE BOND

  1. Wire Bonding: Au Ball, Au Wedge, Al Wedge
  2. Wire Bond: PCB, Rigid-Flex and Flex plating
  3. Auto Die AttachAu Ball and Al Wedge Bond Pad Size on PCB or Flex
  4. Au Ball Bond: Pad size, Pad pitch vs. Wire diameter
  5. Al Wedge Bond: Pad size, Pad pitch vs. Wire diameter
  6. Wire Bond Pull Test (DPT), MIL-STD-883 TM2011
  7. Wire Bond Deformation, MIL-STD-883 TM2017
  8. Wire Bond: electrical resistance and burn-out current

DISPENSE and ENCAPSULATION

  1. Dispense and Encapsulation Assembly Guidelines
  2. Dispense and Encapsulation Applications
  3. Dispense and Encapsulation Process Considerations

High Resolution AOI, XRAY and METROLOGY

  1. 2D + 3D High Resolution AOI for Microelectronics
  2. Microfocus 160Kv XRAY Inspection (including Flip Chip)
  3. Metrology: Measurement of Substrate and Assembly

MICROELECTRONICS: clearly the SMT market is trending fast to ultra-small Semiconductor industry requirements.

“AmTECH specializes in Advanced Microelectronics with SMT, Flip-Chip, Die-Attach, Wire-Bond and Encapsulation on PCB, Rigid-Flex, Flex and Ceramic substrates”.

1. AUTO DIE PICK-N-PLATE: Datacon EVO Plus

Description Standard Production
Wafer Size 4” – 12”/ (100mm – 300mm)
Frame Size 14.96”/ 380mm (300mm wafer diameter)
Die Size 10 mils²/ 250um² to 1”/ 25mm²
Die Thickness 4mils/ 100um to 28mils/ 700um
Die pick from: Wafer: Film Frame or Grip Ring/ Stretch Ring
Die place to: Waffle Pack or Gel-Pak 2”x2” and 4”x4”
Visual Inspection 30x to 60x magnification

2. DIE ATTACH

Die Attach, also known as Die Bond, is the process of attaching a die or multiple die to a Printed Circuit Board, Rigid Flex, Flex or Ceramic substrate. Precision X/Y placement accuracy and repeatability requirements for die placement and die height are critical in Microelectronic products for Automotive/LiDAR, Medical/Biotech, Industrial, Automation and many other applications.

  • Epoxy die attach is the most common die attach process.

Precision die attach using conductive, non-conductive epoxy or DAF.

3. AUTO DIE ATTACH: Datacon EVO Plus

  • Precision die attach using conductive, non-conductive epoxy or DAF.
Description Standard Production
XY Placement +/-7um @3s (+/-15um/ 0.6 mils after epoxy cure)
Theta Placement +/-0.15° accuracy
Max. Die Tilt <1.0mm die size = 12um, ≥1.0mm die size = 25um
Bond Line Thickness BLT = 25-50um (1-2mil)
Die Size 10 mils²/ 250um² to 2”/ 50mm²
Die Thickness 4mils/ 100um to 28mils/ 700um
Die pick from: Wafer (4”-12”), Waffle Pack or Gel-Pak
Die place to: PCB, Rigid-Flex, Flex or Ceramic substrate
Visual Inspection 30x to 60x magnification

4. MANUAL DIE ATTACH: Vacuum wand under microscope

  • Die attach using conductive, non-conductive epoxy or DAF.
Description Standard Production
XY Placement +/-75um (3 mils) accuracy
Theta Placement +/-5° accuracy
Max. Die Tilt <1.0mm die size = 25um, ≥1.0mm die size = 50um
Bond Line Thickness BLT = 25-50um (1-2mil)
Max. Die Size 1”/ 25mm²
Min. Die Size 10 mils²/ 250um²
Die Thickness 4mils/ 100um to 28mils/ 700um
Die pick from: Wafer (4”-12”), Waffle Pack or Gel-Pak
Die place to: PCB, Rigid-Flex, Flex or Ceramic substrate
Visual Inspection 30x to 60x magnification

5. DIE ATTACH: Pad Size vs. Die Size

  • Die Attach Pad size (L x W) vs. Die size.
Document Die Size Die-Attach Pad Size
Comply with
MIL-STD-883
L x W

D/A Pad Length ≥ L+ 500 um (20mil)
D/A Pad Width ≥ W + 500 um (20mil)

Do not comply with
MIL-STD-883

L x W

D/A Pad Length ≥ L+ 250 um (10mil)
D/A Pad Width ≥ W + 250 um (10mil)

6. Advanced FLIP CHIP ASSEMBLY: Datacon EVO Plus

  • Flip Chip is a method of interconnecting IC chips with solder bumps/balls that have been deposited onto the top-side IC chip pads to a substrate. The IC chip is flipped over during assembly so that its top-side faces down. Solder balls are eutectic (Sn63Pb37) or lead free (SAC305).

Contact Pitch
um (mil)

Ball/ Bump Size
um
PCB Pad Size
um
PCB Pad Size
Variation
300um (12mil) 150-160um 160um 150-160um
250um (10mil) 125-135um 135um 125-135um
200um (8mil) 100-110um 110um 100-110um
150m (6mil) 75-85um 85um 75-85um

 

Description Standard Production
Flip-Chip Ball or Bump Eutectic Sn63Pb37 or Lead-free SAC305
Flip-Chip Attach Gel Flux clean or no-clean
Underfill Namics 8437-2
Max. Die Size 1”/ 25mm²
Min. Die Size 20 mils²/ 500um²
Die Thickness 6mils/ 0.15mm to 40mils/ 1mm
Flip-Chip to PCB Edge 20 mil/ 500um
F/C to SMT Component 20mil/ 500um
Flip-Chip Pick from: Waffle Pack 2”x2” and 4”x4”
Flip-Chip place to: PCB, Rigid-Flex, Flex or Ceramic substrate
Visual Inspection 25-160 kV XRAY, <1um detail detectability

7. WIRE BONDING

There are three main wire bonding processes that are used for interconnecting bare-die IC Chip to PCB, Rigid-Flex, Flex or Ceramic substrates.

  • Gold Ball Wire Bonding (Thermosonic @ +150°C)
  • Gold Wedge Wire Bonding (Ultrasonic @+150°C)
  • Aluminum Wedge Wire Bonding (Ultrasonic @+25°C)

8. WIRE BOND: PCB, Rigid-Flex and Flex gold plating

  • Gold plating must be < 90 Knoop hardness, 99.99% (4N) pure gold.
  • Electroless Ni/ Electroless Pd/ Immersion Au, ENEPIG, IPC-4556
IPC-4556 ENEPIG Thickenss
3rd level Au ≥0.1 um (≥ 4 uinches) Immersion Gold
2nd level Pd 0.05 – 0.30 um (2 – 12 uinches) Electroless Palladium
1st level Ni 3-6 um (118 – 236 uinches) Electroless Nickel
  • Gold plating must be < 90 Knoop hardness, 99.99% (4N) pure gold.
  • Electroless Ni/ Immersion Au, ENIG, IPC-4552
IPC-4552 ENIG Thickenss
3rd level Au ≥0.05 um (≥ 2 uinches) Immersion Gold
1st level Ni 3-6 um (118 – 236 uinches) Electroless Nickel

9. AU BALL and AL WEDGE BOND PAD SIZE on PCB or Flex:

Description Design Guideline
PCB Bond Pad Size (rectangular) ≥ 100 x 300um (4x12mil) Preferred
PCB Bond Pad Size (square) ≥ 200 x 200um (8x8mil) Optional
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 or LDI: 10 – 20um (0.4-0.8mil)
Solder mask alignment tolerance LPI ≤ +/-50um; LDI ≤ +/-25um

10. AU BALL WIRE BOND: (ENEPIG)

  • Thermosonic @ +150°C, Wire Bond Area = 80x56mm (3.15”x2.2”)
  • 20um, 25um and 32um wire diameter for standard production

Wire Diameter Size
um (mil)

Wire Length (mm) IC Pad Size
um (min)
IC Pad Pitch
um (min)
Staggered Pitch
(min)
18um (0.7mil) * ≥0.3≤2.5mm ≥40um ≥50um 25/50um
20um (0.8mil) ≥0.3≤3.0mm ≥45um ≥55um 28/56um
25um (1.0mil) ≥0.3≤3.5mm ≥55um ≥65um 33/66um
32um (1.25mil) ≥0.4≤4.0mm ≥70um ≥90um 45/90um
38um (1.5mil) * ≥0.5≤5.0mm ≥80um ≥100um 50/100um

11. AL WEDGE WIRE BOND: (ENIG)

  • Ultrasonic @ +25°C, Wire Bond Area = 250x200mm (10”x8”)
  • 20um, 25um and 32um wire diameter for standard production

Wire Diameter Size
um (mil)

Wire Length (mm) IC Pad Size
um (min)
IC Pad Pitch
um (min)
Staggered
Pitch

um (min)
18um (0.7mil) * ≥0.3≤5.0mm ≥50um ≥60um 30/60um
20um (0.8mil) ≥0.3≤6.0mm ≥55um ≥65um 33/66um
25um (1.0mil) ≥0.3≤7.0mm ≥65um ≥75um 38/76um
32um (1.25mil) ≥0.4≤8.0mm ≥80um ≥100um 50/100um
38um (1.5mil) * ≥0.5≤10.0mm ≥100um ≥120um 60/120um

12. 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

13. 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 5x
wire diameter 

Gold Crescent
(Tailless Bond)
Crescent: 1.2x to 5x
wire diameter in width
and 0.5x to 3x
wire diameter in length

Aluminum Wedge Bond (Foot)
Bond Width:1.2x to 3x wire diameter
Bond Length: 1.5x to 5x wire diameter

Gold Wedge Bond (Foot)
Bond Width: 1.5x to 3x wire diameter
Bond Length: 1.5x to 5x wire diameter

Al or Au Wedge Wire Bond Tail
≤2x wire dia. Die, PCB or Package

14. WIRE BOND: electrical Resistance and burn-out Current

Wire Dia. um Gold 4N Al, 1%Si Gold 4N Al, 1%Si
Resistance Ω(mm²)/m 0.0222 0.0278 Length ≥1mm Length ≥1mm
Electrical Resistance Ohm/m I max Burn out current, Amps
18um (0.7mil) 0.38A 0.21A
25um (1mil) 44.82Ω/m 55.01Ω/m 0.63A 0.47A
32um(1.25mil) 27.36Ω/m 33.57Ω/m 0.91A 0.68A
38um (1.5mil) 19.40Ω/m 23.81Ω/m 1.17A 0.88A

15. DISPENSE and ENCAPSULATION Assembly Guideline:

  • Glob Top, Dam & Fill, Underfill and UV
PROCESS DESCRIPTION DIMENSION (min)
um (mils)
Glob Top Overlap of Encapsulation to Wire Bond
on PCB, substrate or package
≥600um (24 mils)

Glob Top or
Dam & Fill

Overlap of Encapsulation
to Top of Wire Bond Loop
≥200um (8 mils)
Glob Top or
Dam & Fill
Space Fiducial to Glob Top or Dam ≥250um (10 mils)

Glob Top or
Dam & Fill

Fiducial Size (Round Pad) ≥250um (10 mils)
Dam & Fill Space Wire Bond Pad edge to Dam ≥200um (8 mils)
Dam & Fill Dam Width minimum ≥400um (16 mils)
Dam & Fill Dam Height maximum *
(2x Dam width using Tall Dam material)
≤800um (32 mils) *

16. DISPENSE and ENCAPSULATION Applications:

  • Glob top is a one-part process for small-medium die with wire bonds
  • Glob top with rigid black encapsulant for high reliability applications
  • Glob top with flexible UV light/moisture-cure clear encapsulant
  • Dam & Fill is a two-part process for large die with wire bonds
  • Underfill dispensing for CSP and Flip-Chip components
  • Die-Attach epoxy dispensing: conductive (silver) and non-conductive

17. DISPENSE and ENCAPSULATION Process Considerations:

  • Shelf life @ -40°C temperature: 9-months
  • Thaw: Warm up 1-2 hours @ +25°C prior to use (Do not re-freeze)
  • Pot life @ +25°C (working life): 48-hours (2-days)
  • Substrate pre-heat to +80°C to +100°C for void-free encapsulation
  • Rework of encapsulation can only be performed prior to cure
  • Encapsulant must be cured within 1-hour to reduce moisture absorption

18. Advanced 2D + 3D High Resolution AOI for Microelectronics

Description 2D + 3 D High Resolution AOI Specification
Top-Down Camera 12 Mega Pixel
4-Side Camera 6 Mega Pixel
Field of View (FOV) 21x21mm (0.83”x0.83”)
3D Resolution 9.0um (0.35mil)
2D Resolution 7.2um (0.28mil)
Max.  Component Height 8.0mm (315mil)
3D Acquisition Rate 140 fps (frames per second)
Projector Power 3X Standard Resolution
Projector LED Blue
  • Multi-function system with (1) top-down and (4) side cameras
  • Advanced 2D + 3D High Resolution AOI, min. component size 01005
  • Maximum Inspection Area: L480 mm x W400 mm (19”x16”)
  • Part Defects: position, missing, wrong, polarity, skew, tombstone
  • Lead Defects: bent, lifted, tilted, bridging
  • Solder Defects: open, short, insufficient, solder balls

19. Microfocus 160Kv XRAY INSPECTION (including Flip Chip)

  • Extended BGA and Flip-Chip Inspection including “VOID” analysis
  • SMT and Advanced Microelectronics Assembly Inspection
  • Semiconductor Packaging including Wire Bonding inspection
  • Bottom Termination Components: QFN, BGA, LGA, CSP, Flip-Chip
  • 2000X geometric magnification and 17,500X image magnification
  • X-Ray tube with 25-160 kV voltage range, and <1 um detail detectability

20. METROLOGY: measurement of substrate and assembly

  • Precision X, Y, and Z Linear Ways, Programmable Zoom Lens
  • XY=2.6um+L/175, Z=3.0um+L/150 accuracy, 315x315mm work area
  • Camera and Optics: High-Res Color, Zoom Range 36:1 (15x-540x)
  • InSpec Metrology Software: point & click, proprietary edge detection
  • Advanced Illumination: Multi-Ring LED Lighting: Surface, Profile and Axial