Lock-in thermography application in flip-chip packaging for short defect localization

The efficiency of short fault isolation in flip-chip packaging has been increased greatly using the newly developed infrared lock-in thermography (IR-LIT) technique. Because the current concentration is always higher at the short location, shorts are equivalent to a heat source that can be detected by IR-LIT. This paper presents case studies using IR-LIT as a fault isolation tool and shows IR-LIT is more useful in isolating defects in flip-chip-packaged microprocessor devices than other techniques like superconducting quantum interface device (SQUID) and photon emission (PEM) microscopy. This paper also demonstrates integration of IR-LIT into the standard electrical failure analysis flow for short failures.