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Purpose
- Review applications of CT for failure
analysis in electronics and systems
- Discuss limitations of current CT
technology
- Provide an outlook on future technologies
Failure analysis with X-ray CT: state-of-the-art, limitations and - - PowerPoint PPT Presentation
Failure analysis with X-ray CT: state-of-the-art, limitations and - - PowerPoint PPT Presentation
Failure analysis with X-ray CT: state-of-the-art, limitations and future developments Philipp Schtz Iwan Jerjen and Peter Jacob Empa Laboratory for Eletronics/Metrology/Reliability Dbendorf, Switzerland philipp.schuetz@empa.ch
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Outline
- How to record a Computed Tomography?
- Which errors on IC and board level can be
identified?
- How to investigate time-dependent
phenomena and errors on system level?
- Where are the current limitations?
- Which future developments might close
the gap?
- What did we learn?
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How does a CT work?
source
- bject
detector array manipulator
Generic setup CT-system Measurement principle: Rotate the sample and record for each
- rientation X-ray projections
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How does a measurement work?
Example: Capacitor Recorded X-ray images (sinogram)
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How does a measurement work?
Recorded X-ray images (sinogram) Recorded X-ray images (sinogram) Different rotation angles
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How to get virtual cross-section?
Central slice for different phases of reconstruction Reconstruction process: Determine material and density distribution from projection information
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Bond Detachment in a chip
3D view of broken bond wires (gap 5 – 10 μm) Tomographic cross section
- P. Jacob et al., Proc. from the 36th Intern. Symposium for Testing
and Failure Analysis, November 14 – 18, 2010, Addison Texas, p. 444
Mechanically polished cross section
20 μm
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Imaging aluminum bond wires
Goal: Investigate aluminum bond wires
Aluminum bond wires Aluminum bond wires Aluminum bond wires Aluminum bond wires Lead frame (strongly absorbing material) Chip structures visible
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Electrical stress on vias
New VIA VIA after electrical stress Destroyed VIA
Goal: Investigate degradation of VIA under electrical stress.
100 μm
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Failure analysis in capacitors
Goal: Find causes for a shortcut in a capacitor Metallic connection Broken electrolyte layer
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Arcing within a diode
Goal: Investigate roll-over in diode
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128 mm
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Analysis of arc channel
Goal: Analyse form and properties of arc channel
Interior surface
- f plastic isolator
after voltage arcing
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Mechanical or electronic stress
Question: Did the fuse break or melt?
Electric stress: Mechanical stress may lead to edgy surfaces.
- Rounded surfaces
- Droplets of molten
metal
Fuse wire after
- vercurrent
Droplets of molten metal Rounded surfaces
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Inspection of solder points
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Goal: Identify broken solder points
Steel casing RPM-meter 4 mm wall
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Resonance behaviour
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Goal: Determine resonance behaviour of components in a transformer
Movement of components measured by laser interferometry. Position of opening and mobile parts determined by CT.
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Monitoring processes
Key question Can CT monitor time-dependent processes? Answer Yes, if a) process slower than measurement b) Process can be halted
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Freezing processes
Decharging of a battery New Empty
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Processes involving organic material
Deposition points of chalk in aerator
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Challenges
- Detect failures of sub-micrometer size in
large samples Example: Microcracks in a chip
- Examining interfaces of materials with
different attenuation behavior Example: Interface mold gold wire
- Lowering the speed limit on processes to
be monitored.
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Example for bad interface recognition
Strongly absorbing materials cause artifacts impeding a reliable examination of the interface region
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Differential Phase Contrast - CT
X-ray source Test object Grids
Schematic presentation
- f X-ray attenuation and
refraction Schematic of Talbot-Lau Interferometer
[1] Jerjen et al., Opt. Expr., 19, 13604 - 13611 (2011). [2] Revol et al., J. Appl. Phys, 110, 044912 (2011)
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Why is DPC an interesting development?
Measured by conventional CT Measured in DPC-CT less artifacts from strongly absorbing material (gold) Materials indiscernible in attenuation imaging may be visible in DPC.
Advantages of DPC
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Water in bricks
Jerjen et al., Fachtagung industrielle CT, Wels, Austria, 2010
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Identifying small pores in a large specimen
Conventional CT DPC Imaging High resolution CT Sub-pixel pores can be identified with DPC imaging. Microscopic pores can be detected with large field of view
Revol et al, J. Appl. Phys. 110, 044912 (2011)
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CT-equipment at Empa
Microfocus-System Industrial X-ray CT-System Industrial X-ray CT-System Linac X-ray CT-System
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CT-equipment at Empa
Diameter 1 mm 1 cm 10 cm 1 m Nanofocus-CT Industrial CT Linear accelerator Mikrofocus-CT Resolution 0.1 mm 1 mm 0.01 mm 0.001 mm
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Conclusions
- CT allows a non-destructive failure analysis
- Broad range of length scales can be investigated
from bond wires to complete systems.
- Large variety of materials and combinations can
be examined.
- Challenging are interfaces of disparate materials
and tiny failures with respect to the system size
- New developments such as differential phase