AOI and X-ray Inspection of PCB Assemblies

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Oscar Webb
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1 AOI and X-ray Inspection of PCB Assemblies Electronic Materials and Assembly Processes for Space (EMPS) Workshop HYTEK, Aalborg, Denmark 29th May 2013 Automatic Optical Inspection (AOI) and X-ray Inspection of PCB Assemblies By Kim Plauborg Director, Space Electronics Terma A/S 2013 Terma A/S 29 May

2 AOI and X-ray Inspection of PCB Assemblies Man against Machine 2013 Terma A/S 29 May

3 Inspection Requirements Visual = Seen or able to be seen by the eye 2013 Terma A/S 29 May

4 Inspection Requirements Visual = Seen or able to be seen by the eye 2013 Terma A/S 29 May

5 Human visual inspection Is human visual inspection effective? 2013 Terma A/S 29 May

6 What is Automatic Optical Inspection Automatic Optical Inspection (AOI) is a cost effective solution to replace traditional human inspection and provide assemblers of printed circuit boards a quick, reliable and consistent system to inspect their boards, either before or after reflow/wave solder. Principle of operation The board is lit by several light sources while the system visually scans the surface of the PCB. For each device type the system is programmed to test for a number of parameters. More than the eyes can see 2013 Terma A/S 29 May

7 What Automatic Optical Inspection can detect What can be detected? Area Defects Billboarding Component offset Component polarity Component presence/absence Component skew Excessive solder joints Flipped component Height Defects Insufficient paste around Leads Insufficient solder joints Lifted leads No-population tests Paste registration Severely damaged components Solder bridges Tombstoning Volume defects Wrong part etc 2013 Terma A/S 29 May

8 What Automatic Optical Inspection can detect Examples of defects found Lifted lead 2013 Terma A/S 29 May

9 What Automatic Optical Inspection can detect Examples of defects found Misaligned lead 2013 Terma A/S 29 May

10 What Automatic Optical Inspection can detect Examples of defects found Insufficient solder 2013 Terma A/S 29 May

11 What Automatic Optical Inspection can detect Examples of defects found Tombstoning 2013 Terma A/S 29 May

12 What Automatic Optical Inspection can detect Examples of defects found Additional part 2013 Terma A/S 29 May

13 What Automatic Optical Inspection cannot detect AOI also has some limitations with e.g.: Heel soldering of flatpack devices Array devices and other devices with solder joints under the package Densely populated boards 2013 Terma A/S 29 May

14 What Automatic Optical Inspection cannot detect Example of false errors Adjacent tantalum capacitors are shading the light 2013 Terma A/S 29 May

15 What Automatic Optical Inspection cannot detect Example of defect not found Insufficient solder under the package 2013 Terma A/S 29 May

16 X-ray Inspection X-ray inspection is an important supplement to the AOI and human visual inspection for array devices and other devices with solder joints under the package. The traditional inspection is not an option as the majority of solder connections to the PCB are not visible Terma A/S 29 May

17 What can we use X-ray Inspection for We use X-ray inspection for: Bare PCBs Suspected counterfeit parts Solder joints including voids for array devices, large SMD devices, etc Foreign objects Porosities as a result of solder joint or lead fatigue Defective parts 2013 Terma A/S 29 May

18 What can we use X-ray Inspection for Examples of defects found Foreign object 2013 Terma A/S 29 May

19 What can we use X-ray Inspection for Examples of defects found Poor heel soldering Voids 2013 Terma A/S 29 May

20 What can we use X-ray Inspection for Examples of defects found Good solder joint on CCGA Solder joint with lots of voids 2013 Terma A/S 29 May

21 AOI and X-ray Inspection of PCB Assemblies AOI Statistics from recent production lot of 10 flight grade space PCB assemblies Total Procentage Inspection points ,0% Total faulty points 878 5,3% Real faulty point 242 1,5% False faulty points 636 3,8% Good points ,7% 94,7% Real faulty point 3,8% 1,5% False faulty points Good points 2013 Terma A/S 29 May

22 AOI and X-ray Inspection of PCB Assemblies Statistics on real faulty inspection points False faulty points Real faulty point Total faulty points Component Extraction Polarity Fillet Manco Missing Component Wettability Lead Extraction Tombstone Other Vertical Shift Land Extraction Lead Bend Horisontal Shift Bridge Exceeding of Window Range No Electrode Total Component Extraction Polarity Fillet Manco Missing Component Wettability Lead Extraction Tombstone Other Vertical Shift Land Extraction Lead Bend Horisontal Shift Bridge Exceeding of Window Range No Electrode 2013 Terma A/S 29 May

23 AOI and X-ray Inspection of PCB Assemblies Is AOI a fully adequate inspection method? 2013 Terma A/S 29 May

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