Metrology and analysis

Which method is used to observe solder joint voids and wire shapes inside a package in three dimensions without destroying it?

  1. AEllipsometry
  2. BSIMS
  3. CX-ray CT
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Answer: C. X-ray CT

X-ray CT captures X-ray transmission images from many directions and computationally reconstructs a 3D image of the interior. Without destroying the package, voids and bridges in BGA solder balls, wire deformation and internal cracks can be observed.

  • A. Ellipsometry measures thin-film thickness and optical constants.
  • B. SIMS is a destructive method that analyzes elements while sputtering the sample.
  • C. Correct. The interior is reconstructed in 3D from X-ray transmission images.
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More Metrology and analysis questions

  1. Which tool is widely used to find delamination at interfaces inside a package, such as between molding compound and chip, non-destructively?
  2. Which method evaluates the quality of compound semiconductor wafers and epi layers without contact by shining laser light and measuring the spectrum and intensity distribution of the emitted light?
  3. Compared with bright-field wafer inspection, which images patterns directly, what characterizes dark-field inspection, which captures only scattered light?
  4. Which instrument traces a sample surface with a fine stylus and measures step heights and surface shape from the stylus's vertical motion?
  5. What is the technique called that uses statistical models to predict film thickness or dimensions of wafers that were not actually measured, from equipment sensor data and the like?