Development of Cu-core Pb-free solder bumps
Development of Cu-core Pb-free solder bumps
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DOI：
10.1149/1.1830354
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发表时间：
2005
影响因子：
3.9
通讯作者：
Daobin Mu;K. Kondo;Junpei Maeda
中科院分区：
文献类型：
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作者：
Daobin Mu;K. Kondo;Junpei Maeda
采用电沉积结合光刻技术制备了铜芯无铅焊料凸点。用80 mm厚的干膜抗蚀剂成功地实现了间距为100 mm、直径为50 mm的凸点。在最佳工艺条件下，凸点达到了50 6 5 mm的目标高度。采用虚拟图形提高了凸点的高度均匀性。拉伸测试结果表明，铜凸块的剪切强度约为45 gf！通过对铜箔表面进行软刻蚀预处理，Sn-Zn、Sn-Ag、Sn-Cu和Sn-Bi镀层被沉积为具有近共晶成分的无铅焊料。特别是，锡-锌焊料电镀/铜的界面特性进行了研究，回流后，在这项研究中，以及Ni镀层作为下球冶金层的化合物形成的界面上的效果。结果表明，在回流焊后的Sn-Zn镀层/Cu界面上存在Y-Cu_5 Zn_8化合物层。Ni镀层抑制了Y-Cu_5 Zn_8界面化合物的形成。
Cu-core Pb-free solder bumps were developed by electrodeposition in combination with photolithography. A bump with a pitch of 100 mm and a diam of 50 mm was successfully achieved with dry film resist~80 mm thick! under optimum process conditions, and the bumps reached the target height of 50 6 5 mm. The adoption of a dummy pattern improved the height uniformity of the bumps. Pull test results showed that the shear strength of the Cu bump ~around 45 gf! was obtained by the soft-etching pretreatment of the Cu foil surface. Sn-Zn, Sn-Ag, Sn-Cu, and Sn-Bi platings were deposited as Pb-free solders with near-eutectic compositions. In particular, the interface properties of Sn-Zn solder plating/Cu were investigated after reflowing in this study, as well as the effect of Ni plating as an under ball metallurgy layer on compound formation at the interface. It was found that a compound of Y-Cu5Zn8 layer existed in the interface of the reflowed Sn-Zn plating/Cu. The Ni plating layer inhibited the formation of the interface Y-Cu5Zn8 compound with reflowing.