Joint structure in high brightness light emitting diode (HB LED) packages

We present the transmission electron microscopy (TEM) analysis of 1.5 μm-thick Au–20Sn solder joint between a high brightness light emitting diode (HB LED) and a Si heat sink. Due to intermetallic compound formation, global Sn depletion occurred in the thin solder, which raised the melting point of the solder and caused local incompleteness of bonding.