Investigation on fluxless laser jet bumping technology
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摘要: 为了研究在氮气保护条件下,无钎剂激光喷射植球工艺参数对凸点剥离强度的影响,对激光电流、激光脉冲时间和凸点剥离强度的关系进行了试验,得出了激光脉冲时间一定时,剥离强度随激光电流的增加而降低;激光电流一定时,剥离强度随脉冲时间的增加而增加的结果;同时借助扫描电镜和能谱分析,对凸点(Sn63Pb37)/焊盘(Au/Ni/Cu镀层)界面的组织形貌及相组成进行了分析.结果表明,在保证凸点外观质量的前提下,大激光电流、短激光脉冲时间时凸点剥离强度较低,小激光电流、长激光脉冲时间时凸点剥离强度较高;在现试验条件下,钎料球能很好地润湿焊盘并在凸点/焊盘界面处形成了连续的AuSn4金属间化合物层.Abstract: The effect of the technology parameters(laser current,laser pulse time and N2 pressure) for fluxless laser jet bumping on the bump's peel strength under N2 protecting conditions were investigated;the interfacial microstructure and composition of the intermetallic compound at bump(Sn63Pb37)/pad(Au/Ni/Cu) were analyzed in term of scanning electron microscopy and energy dispersive spectrometer.As the laser pulse time is constant,the peel strength decreases with increasing laser current;as the laser current is constant,the peel strength increases with increasing laser pulse time.In case of obtaining good bump's appearance,larger laser current along with shorter pulse time results in the decrease of bump's peel strength,smaller laser current along with longer pulse time increases bump's peel strength.Under existing test conditions,solder ball(Sn63Pb37) may wet the pad(Au/Ni/Cu) commendably.The continuous AuSn4 intermetallic compound layer is formed at the bump/pad interface and AuSn4 is detected in the solder pump near the interface.
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Keywords:
- laser technique /
- laser jet bumping fluxless /
- peel strength /
- microstructure
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