Shin, CX Baik, YJ Huh, JY 2024-01-21T11:43:30Z 2024-01-21T11:43:30Z 2021-09-04 2001-10 0361-5235 https://pubs.kist.re.kr/handle/201004/140168 The shear strength of ball-grid-array (BGA) solder joints on Cu bond pads was studied for Sn-Cu solder containing 0, 1.5, and 2.5 wt.% Cu, focusing on the effect of the microstructural changes of the bulk solder and the growth of intermetallic (IMC) layers during soldering at 270 degreesC and aging at 150 degreesC. The Cu additions in Sn solder enhanced both the IMC layer growth and the solder/IMC interface roughness during soldering but had insignificant effects during aging. Rapid Cu dissolution from the pad during reflow soldering resulted in a fine dispersion of Cu6Sn5 particles throughout the bulk solder in as-soldered joints even for the case of pure Sn solder, giving rise to a precipitation hardening of the bulk solder. The increased strength of the bulk solder caused the fracture mode of as-soldered joints to shift from the bulk solder to the solder/IMC layer as the IMC layer grew over a critical thickness about 1.2 mum for all solders. The bulk solder strength decreased rapidly as the fine Cu6Sn5 precipitates coarsened during aging. As a consequence, regardless of the IMC layer thickness and the Cu content of the solders, the shear strength of BGA solder joints degraded significantly after 1 day of aging at 150 degreesC and the shear fracture of aged joints occurred in the bulk solder. This suggests that small additions of Cu in Sn-based solders have an insignificant effect on the shear strength of BGA solder joints, especially during system use at high temperatures. English MINERALS METALS MATERIALS SOC FATIGUE-CRACK GROWTH THERMAL FATIGUE AG SOLDER COPPER RELIABILITY COMPOUND Effects of microstructural evolution and intermetallic layer growth on shear strength of ball-grid-array Sn-Cu solder joints Article 10.1007/s11664-001-0119-7 1 JOURNAL OF ELECTRONIC MATERIALS, v.30, no.10, pp.1323 - 1331 JOURNAL OF ELECTRONIC MATERIALS 30 10 1323 1331 scie scopus 000171658300009 2-s2.0-0035484575 Engineering, Electrical & Electronic Materials Science, Multidisciplinary Physics, Applied Engineering Materials Science Physics Article FATIGUE-CRACK GROWTH THERMAL FATIGUE AG SOLDER COPPER RELIABILITY COMPOUND BGA solder joint ball shear strength Sn-Cu solder intermetallic compound fracture mode