Title :
Fluxless reflow of eutectic solder bump using formic acid
Author :
Lin, Yong-Shan ; Shih, Chun-Hsing ; Chang, Wei
Author_Institution :
Dept. of Electr. Eng., Yuan Ze Univ., Chungli, Taiwan
Abstract :
This work elucidates the solder reflow of eutectic (63Sn/37Pb) solder bump using fluxless formic acid. The dependences of formic acid reflow on metallic oxide reduction are investigated experimentally for eutectic solder bump. Appropriate temperature profile and sufficient formic acid concentration are the key factors to optimize the metallic oxide reduction during thermal reflow. A positive pressure in process chamber is beneficial to control the variations of unwanted oxygen and the regrowth of metallic oxide during mechanical wafer switching. A reflowed solder joint degrades considerably under shear strength testing after several reflow times.
Keywords :
eutectic alloys; lead alloys; shear strength; solders; tin alloys; Sn-Pb; eutectic solder bump; fluxless reflow; formic acid concentration; mechanical wafer switching; metallic oxide reduction; positive pressure; process chamber; shear strength testing; solder joint; thermal reflow; Charge carriers; Charge measurement; Circuits; Current measurement; Electron beams; Probes; Radiative recombination; Scanning electron microscopy; Semiconductor materials; Spontaneous emission; eutectic solder bump; flip chip package; fluxless reflow; formic acid;
Conference_Titel :
Integrated Circuits, ISIC '09. Proceedings of the 2009 12th International Symposium on
Conference_Location :
Singapore
Print_ISBN :
978-9-8108-2468-6
