Effect of gold concentration through a single dynamic wave soldering process

Gold possesses a unique combination of properties of particular value in the construction and operation of electrical and electronic equipment. These properties include low electrical resistivity and contact resistance, ease of thermal compression and high resistance to mechanical wear. Most efficient use is by employing gold, usually in the electroplated form, either as an intermediate layer in certain microelectronic devices, or as a finishing on such components as connectors, terminations, and printed circuits. This paper presents a study of interaction between tin-lead solder and pin, which are associated with intermetallic compound (IMC) after undergoing dynamic wave soldering. The aim of the study was to determine the effect of IMC formation to joint reliability by verifying the gold concentration as IPC J-Standards guidelines of a minimum of 3 wt% [1] [2] In our case study, the gold pins (without pre-tinned) are actually inserted directly into PCB and passed through dynamic wave soldering using wave pallet. The surface scanning electron microscopy and energy dispersive x-ray were used to reveal the concentration of gold present in the IMC microstructure after undergoing wave soldering (inserted into PCB). It was found that no gold presence for a thin PCB (thickness: 0.0596 in or 1.514 mm) and small percentage of gold presence (less than a minimum of 3 wt %) for a thick PCB (thickness: 0.30 in or 7.62 mm). Therefore, a double hot dip process is not required prior to assembly process.