(中南大學 材料科學與工程學院，長沙 410083)
摘 要: 采用回流焊技術制備AuSn20/Ni焊點，通過掃描電子顯微鏡(SEM)及能譜分析(EDX)研究AuSn20/Ni焊點界面反應特征，探討退火溫度和時間對AuSn20/Ni焊點顯微組織和剪切強度的影響。結(jié)果表明：AuSn20/Ni焊點在300 ℃釬焊90 s后，焊料內(nèi)部產(chǎn)生ζ′-Au5Sn+δ-AuSn共晶組織和棒狀(Ni,Au)3Sn2相。焊點在150 ℃退火時，界面反應速度較慢，金屬間化合物(IMC)層厚度隨著退火時間延長而緩慢增大；焊點的剪切強度隨退火時間延長有較小幅度下降。在200 ℃退火時，AuSn20/Ni的界面反應速度較快，焊料/Ni界面形成(Au,Ni)Sn+(Ni,Au)3Sn2復合IMC層。焊點的剪切強度隨退火時間延長呈較大幅度下降。從焊點力學可靠性方面考慮，AuSn20/Ni焊點不宜在200 ℃及以上溫度長時間服役。
關鍵字: AuSn20/Ni焊點；界面反應；金屬間化合物(IMC)；剪切強度
（School of Metarials Science and Engineering, Central South University, Changsha 410083, China）
Abstract:The AuSn20/Ni solder joints were prepared by the reflow process. The effects of the aging temperature and time on the microstructure and shear strength were investigated by the scanning electron microscope (SEM) with an energy dispersive X-ray (EDX). The results show that, a fine lamellar eutectic ζ′-Au5Sn+δ-AuSn microstructure and needle-like (Ni,Au)3Sn2 intermetallics are formed at the AuSn20/Ni joint after reflow at 300 ℃ for 90 s. After aging at 150 ℃ for various times，the thickness of the IMC layer at AuSn20/Ni interface grows slightly with the aging time increasing from 150 h to 1 000 h, and the shear strength of the AuSn20/Ni joints declines accordingly. When aging at 200 ℃, the reaction rate of the AuSn20/Ni interface is faster than that when aging at 150 ℃. The thickness of the IMC layer grows rapidly with increasing the aging time while the shear strength of the joints declines almost lightly. Considering the mechanical reliability of the joints, the AuSn20/Ni joints cannot service at 200 ℃ or higher temperature for a long time.
Key words: AuSn20/Ni joints; interfacial reaction; intermetallic compound (IMC); shear strength
