Advanced SMT

Design & Assembly Advanced SMT


  1. PCB Design Guidelines
  2. PCB Pad surface plating finish
  3. Wire Bond: PCB, Rigid-Flex and Flex plating
  4. PCB Panel Requirements
  5. PCB global, image and local Fiducials


  1. Stencil Design Guidelines
  2. Solder Paste


  1. PCB Assembly Documentation
  2. High Performance Solder Paste Printing
  3. High Precision SMT Pick & Place
  4. Advanced Flip Chip Assembly
  5. Convection Solder Reflow and Thermal Profiler

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”.


A well designed and manufactured PCB (Printed Circuit Board) is required for optimum manufacturing assembly yields and electrical performance.

  1. Solder Mask Defined (SMD) pads have solder mask opening that are smaller than metal pads. (≤0.2mm circles/ ≤0.4mm pitch)
  2. Non Solder Mask Defined (NSMD) pads have solder mask openings that are larger than metal pads. (≥0.25mm circles/ ≥0.5mm pitch)
  3. The land pattern size for SMD or NSMD metal pads must be 100% the same size for each component pad.
  4. Use IPC-7351 land pattern calculator and component Technical Data Sheet as a reference for PCB Design pad sizes.
  5. The land to land spacing for passive components ≥ 0.2mm (8 mils).
  6. The land to land spacing for SMT IC’s ≥ 0.5mm (20 mils).
  7. The distance between the bodies of two IC’s ≥ 1.0mm (40 mils).
  8. The space between SMT and PTH components ≥ 2.0mm (80 mils).
  9. All passive components and IC’s shall be parallel to each other and their solder lands perpendicular to the SMT reflow conveyor travel direction.
  10. Similar types of components should be aligned on the board in the same orientation for ease of component placement, soldering and inspection.
  11. Pin #1 on each IC, and connector to be marked on the layout.
  12. Polarity of LED, Diodes and Capacitors to be marked on the layout.
  13. Small passive components, ≤1.0mm pitch IC’s, low profile, and low weight components can be placed on the 2nd side of the PC Board.
  14. Liquid Photo Imaging (LPI) solder mask for 50um (2.0mil) pad clearance.
  15. Liquid Direct Imaging (LDI) solder mask for 25um (1.0mil) pad clearance.
  16. Filled and Flat Vias required on pads to be soldered during reflow process.
  17. Component Keep-Out: ≥3.0mm (120 mils) required in the two long edges of the finished PCB for the conveyor; unless borders on PCB panel.
  18. Minimum drill hole ≥200um (8mil) with ≥ 350um (14mil) annular ring.
  19. Minimum trace width and space: ≥ 100um (4mil). Warp and Twist ≤1%.
  20. Route and Retain for ≥1.6mm thick PCB, V-Score for ≥0.8mm to ≤1.6mm thick PCB, Laser cut for ≤0.5mm thin PCB and ≤0.2mm thin Flex.

2. PCB Pad Surface Plating Finish

Finish NameDescriptionComments
ENEPIGElectroless Nickel, Electroless Palladium, Immersion GoldGold Wire Bond
Fine-Pitch SMT
ENIGElectroless Nickel,
Immersion Gold

Aluminum Wire Bond
Fine-Pitch SMT


Electroless Nickel,
Immersion Silver
No Wire Bonding
Fine-Pitch SMT
Copper OSPOrganic Solderability
Preservative (OSP)

No Wire Bonding
Fine-Pitch SMT

HASLHot Air Solder Leveling
(inconsistent solder thickness)

No Wire Bonding
No Fine-Pitch SMT

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

3rd levelAu≥0.1 um (≥ 4 uinches) Immersion Gold
2nd levelPd0.05 – 0.30 um (2 – 12 uinches) Electroless Palladium
1st levelNi3-6 um (118 – 236 uinches) Electroless Nickel


3rd levelAu≥0.05 um (≥ 2 uinches) Immersion Gold
1st levelNi3-6 um (118 – 236 uinches) Electroless Nickel


DescriptionStandard Production
Panel Size STD≤300x250mm Preferred, ≤500x380mm Maximum
Panel Size MICRO≤100x100mm Preferred, ≤250x180mm Maximum
Panel Thickness STD1.0mm to 5.0mm (40-200mil)
Panel Thickness MICRO0.3mm to 0.8mm (Flex 0.1mm to 0.2mm)
Panel Borders10mm width borders (Minimum 2-sides for conveyor)
Tooling Holes5mm from X and Y Panel/ Board edge (3-holes)
Tooling Hole diameter3mm non-plated hole (120mil)
Soldermask OpeningTooling Hole plus 0.5mm. = 3.5mm (140mil)


  • Fiducial marks facilitate the accurate placement of components.
DescriptionStandard Production
Global Fiducial1.5mm (1.0–1.5mm) solid filled circle (Qty=3)
Image Fiducial1.0mm (0.5-1.0mm) solid filled circle (Qty=3)
Local Fiducial0.5mm (0.25-0.5mm) solid filled circle (Qty=3)
Soldermask Clearance≥0.25mm (10mil)
Soldermask OpeningFiducial diameter plus 0.5mm (20mil)


  • Stencil aperture openings should be 1:1 to PCB pad sizes.
  • Square Pads with 0.05mm radius corners on ≤0.3mm circles.
  • QFN ground pads: 20% volume reduction to avoid “floating”.
  • Windowpane with bracing struts of 0.5mm (20mil) on ≥50mm (200mil) apertures/ solder pads. The resulting apertures should not exceed 50mm (200mil) in any direction.
DescriptionStandard Production
Stencil Thickness5 mil ≥ 0.6mm pitch; 1005 (0402) Passive Components
Stencil Thickness4 mil ≥ 0.5mm pitch; 0603 (0201) Passive Components
Stencil Thickness3 mil ≥ 0.4mm pitch; 01005 Passive Components
Stencil Fabrication5mil Laser Cut
Stencil Fabrication4 mil Laser Cut with optional electro-polish
Stencil Fabrication3 mil Laser Cut with optional gold coating
Aspect Ratio ≥1.5W/T = ≥1.5 (Aperture Width/Stencil Thickness)
Area Ratio ≥0.66L*W / 2*(L+W)*T = ≥0.66 (Aperture Area/ Aperture Walls Area)


  • Solder paste Type 3: 25-45um particle ≥0.25mm circles, ≥0.5mm pitch
  • Solder paste Type 4: 20-38um particle ≥0.20mm circles, ≥0.4mm pitch
  • Solder paste Type 5: 15-25um particle ≥0.15mm circles, ≥0.3mm pitch
  • Storage @ 0-10°C. Shelf life: 6-months @ 0-10°C
  • Pot Life @ +25°C (working life): 2-weeks
  • Thaw: Warm up 3-4 hours @ 25°C prior to use.


  • PCB FAB Drawing, panel drawing, dimensions and FAB notes
  • Gerber Files for PCB Fabrication
  • PCB Assembly Drawing, including Assembly notes
  • Bill of Materials including PN, Designator, Description and Manufacturer
  • Technical Data Sheet for key components including Flip-Chip and Die.
  • Pick & Place Data: XY Centroid Data, and Theta Rotation.


  • Stencil: Laser cut 3-5 mil thick (75-125um). Gold coated for 3 mil
  • Squeegee: 3S Metal, Programmable 45° to 65°
  • Squeegee Pressure: 1.5 to 2.0 lbs. /linear inch. (0.35 Kg/cm)
  • Print Speed: 2.0 to 4.0 in/sec (50-100 mm/sec) 4.0 in/sec optimal
  • Stencil Release Speed: 0.02 in/sec. (0.5mm/sec)
  • Under stencil wiping every 5-10 boards.
DescriptionStandard Specification
Print accuracy+/-5um (0.2mils) @3s accuracy
Print Circle (Min.)150um print diameter (6 mil); 300um (12 mil) pitch
PCB Size50x50mm (2”x2”) to 500x380mm (20”x15”)
Print InspectionAutomatic Print Inspection
Cleaning SystemProgrammable  under Stencil Cleaning System
Vacuum SystemVacuum Print Nest for Thin PCB and Flex (0.1-0.5mm)
Print Head3S Programmable 45° to 65°
ToolingQuick-Tool for PCB support
SubstratePCB, Rigid-Flex, Flex or Ceramic substrate

10. High-Precision SMT PICK and PLACE

  • Placement Accuracy: +/-35um Passive, +/-25um @ 3s IC Components
  • Components: 01005 mm Passive to 45×45 mm IC, ≥0.3 mm pitch
  • Leadless Ultra Small: BTC ≥0.6×0.3×0.3mm to 1x1x0.5mm
  • HM High-speed multi-purpose Pick & Place head (10 nozzles)
  • Number of feeders: 140 Feeders, 8mm width tape reels.
DescriptionStandard Specification
Placement accuracy+/-35um @3s Passive; +/-25um @3s IC Components
Components01005 mm Passive to 45×45 mm IC, ≥0.3 mm pitch
Leadless Ultra SmallBTC ≥0.6×0.3×0.3mm to ≤1x1x0.5mm
PCB Size50x50mm (2”x2”) to 500x380mm (20”x15”)
Pick & Place HeadHM High-speed multi-purpose head (10 Nozzles)
Number of Feeders140 Feeders, 8mm width tape reels

11. 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.
The solder bumps/balls are deposited on the top-side chip pads of the wafer during the final wafer processing steps. Solder balls are eutectic or lead-free.

  • Flip-Chip Assembly: 150um to 300um (6-12 mils) pitch.
  • Ball/Bump Size: 75um to 150um (3-6 mils).

Contact Pitch
um (mil)

Ball/ Bump Size
PCB Pad Size
PCB Pad Size
300um (12mil)150-160um160um150-160um
250um (10mil)125-135um135um125-135um
200um (8mil)100-110um110um100-110um
150m (6mil)75-85um85um75-85um


DescriptionStandard Production
Flip-Chip Ball or BumpEutectic Sn63Pb37 or Lead-free SAC305
Flip-Chip AttachGel Flux clean or no-clean
UnderfillNamics 8437-2
Die Size20 mil²/ 500um² to 1”/ 25mm²
Die Thickness6mils/ 0.15mm to 40mils/ 1mm
Flip-Chip to PCB Edge20 mil/ 500um
F/C to SMT Component20mil/ 500um
Flip-Chip Pick from:Wafer (4”-12”), Waffle-Pack, or Gel-Pak
Flip-Chip place to:PCB, Rigid-Flex, Flex or Ceramic substrate
Visual Inspection160Kv XRAY   

12. CONVECTION Solder Reflow and MOLE Thermal Profiler

LEAD-FREE (RoHS) reflow profile process guideline:

  • Slow Ramp: 130°C to 180°C for 60-90 seconds.
  • Time Above Liquidus (TAL): 40-80 seconds
  • Peak Temperature: 230°C to 250°C.
  • Ramp down to 25°C: 1-4°C per second.
DescriptionStandard Specification
Number of Zones(10) Zone, top and bottom heaters up to 350°C
Heated Tunnel120” Heated Tunnel, plus (2) Cooling Zones
Air or NitrogenAir or Nitrogen reflow with Inert Atmosphere <100 PPM
Thermal ProfilerECD super Mole Gold Thermal Profiler, RF and USB
Thermocouples6-Channel K-Type, 1.5 Million data point memory

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

DescriptionHigh Resolution 3D Specification
Top-Down Camera12 Mega Pixel
4-Side Camera6 Mega Pixel
Field of View (FOV)21x21mm (0.83”x0.83”)
3D Resolution9.0um (0.35mil)
2D Resolution7.2um (0.28mil)
Max. Componenet Height8.0mm (315mil)
3D Acquisition Rate140 fps (frames per second)
Projector Power3X Standard Resolution
Projector LEDBlue
  • 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

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

  • Extended BGA and Flip-Chip Inspection including void analysis
  • SMT and Advancedx 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

15. 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