Metrology and analysis

Which method sends fast pulses into package or board wiring and determines the location of opens or shorts from the reflected waveforms?

  1. AXPS
  2. BTDR (time-domain reflectometry)
  3. CAFM
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Answer: B. TDR (time-domain reflectometry)

TDR injects a fast-rising pulse into a wire and measures the timing and shape of signals reflected where impedance changes. The return time gives the distance and the waveform shows whether it is an open or a short, so it is used to locate package defects.

  • A. XPS examines surface elements and chemical states.
  • B. Correct. Defect locations are found from reflected waves.
  • C. AFM measures surface topography.
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  1. In optical defect inspection, why does detection become sharply harder as particles get smaller?
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