Title :
Comparison of electroplated eutectic Bi/Sn and Pb/Sn solder bumps on various UBM systems
Author :
Jang, Se-Young ; Paik, Kyung Wook
Author_Institution :
Dept. of Mater. Sci. & Eng., Korea Adv. Inst. of Sci. & Technol., Taejon, South Korea
fDate :
10/1/2001 12:00:00 AM
Abstract :
The effect of a reflow process and under bump metallurgy (UBM) systems on the growth of intermetallic compounds (IMC) of the 57Bi/43Sn and 37Pb/63Sn solder bump/UBM interfaces was investigated. The selected UBM systems were sputtered Al/Ti/Cu, sputtered Al/NiV/Cu, Al/electroless Ni/immersion Au, and Al/Ti/electroless Cu. An alloy electroplating method was used for the solder bumping process. The microstructure and composition of intermetallic compound (IMC) phases and their morphologies were examined using scanning electron microscopy and X-ray diffraction. The Cu6Sn5 η´-phase IMC appeared on all Cu containing UBM cases with Pb/Sn and Bi/Sn solders and the Cu 3Sn ε-phase was detected only with Pb/Sn solder bumps. The Ni3Sn4 IMC was found to be the main IMC phase between Ni and solder. The Ni3Sn secondary IMC was also detected on the electroless Ni UBM with PbSn solder after ten times reflow. Through the bump shear test, Al/NiV/Cu, Al/elNi/Au, and Al/Ti/elCu UBMs showed good stability with Bi/Sn and Pb/Sn solder in terms of metallurgical aspects
Keywords :
X-ray diffraction; bismuth alloys; crystal microstructure; electroplating; eutectic alloys; flip-chip devices; integrated circuit interconnections; integrated circuit metallisation; integrated circuit packaging; integrated circuit reliability; interface structure; lead alloys; microassembling; reflow soldering; scanning electron microscopy; tin alloys; Al-Ni-Au; Al-NiV-Cu; Al-Ti-Cu; Al/Ti/electroless Cu UBM; Al/electroless Ni/immersion Au UBM; Bi-Sn solder bump/UBM interfaces; BiSn; Cu3Sn; Cu3Sn ϵ-phase; Cu6Sn5; Cu6Sn5 η´-phase IMC; IMC morphologies; IMC phases; Ni3Sn; Ni3Sn secondary IMC; Ni3Sn4; Ni3Sn4 IMC; Pb-Sn solder bump/UBM interfaces; PbSn; PbSn solder; UBM systems; X-ray diffraction; alloy electroplating method; bump shear test; electroless Ni UBM; electroplated eutectic Bi-Sn solder bumps; electroplated eutectic Pb/Sn solder bumps; flip chip; intermetallic compound composition; intermetallic compound growth; intermetallic compound microstructure; reflow process; scanning electron microscopy; solder bumping process; sputtered Al/NiV/Cu UBM; sputtered Al/Ti/Cu UBM; under bump metallurgy; under bump metallurgy systems; Aluminum alloys; Bismuth; Copper alloys; Gold alloys; Intermetallic; Microstructure; Morphology; Nickel alloys; Tin; Titanium alloys;
Journal_Title :
Electronics Packaging Manufacturing, IEEE Transactions on
DOI :
10.1109/6104.980035
