不同錫銀銲錫厚度對Ni/SnAg/Cu微凸塊介面反應的影響

Abstract

本論文主要研究Cu/Sn2.3Ag/Ni三明治結構的冶金反應，一端的under bump metallization (UBM) 是 20 μm厚、長度 100 μm 的電鍍Cu，另一端UBM則是 125 μm厚的 Ni 箔。試片銲錫厚度介於10~60 μm之間。觀察在經過260℃迴銲測試及150℃高溫儲存測試之後，在試片兩端界面上金屬化合物的微結構的變化。 在經過260℃迴銲測試後，試片兩端界面上的介金屬化合物皆為(Cu,Ni)6Sn5。當銲錫的厚度越來越小，在Cu/2.3Ag界面的介金屬化合物會厚度會越來越厚，而在Ni/2.3Ag界面的介金屬化合物厚度會越來越薄。在Cu/Sn2.3Ag界面上的(Cu,Ni)6Sn5速率常數為0.21 μm/min，在Ni/Sn2.3Ag界面上的(Cu,Ni)6Sn5速率常數為0.11 μm/min。 在150℃高溫儲存測試後，可觀察到在Cu/Sn2.3Ag界面上的(Cu,Ni)6Sn5及Cu3Sn，但在Ni/Sn2.3Ag界面只有(Cu,Ni)6Sn5。當銲錫厚度越小，Cu/Sn2.3Ag界面的介金屬化合物會較厚，Ni/Sn2.3Ag界面的介金屬化合物會較薄。在Cu/Sn2.3Ag界面上(Cu,Ni)6Sn5厚度成長速率常數：8.4 x 10-3 μm/(hr)1/2 ，Cu3Sn厚度成長速率常數: 4.1 x 10-2μm/(hr)1/2 ，在Ni/Sn2.3Ag界面上(Cu,Ni)6Sn5厚度成長速率常數: 2.5 x 10-2μm/(hr)1/2。

In this study, we study the metallurgical reaction in Cu/Sn2.3Ag/Ni sandwich structure. The under bump metallization (UBM) consists electroplated 20 μm-thick Cu with 100 μm diameter on one side. The other UBM is 125 μm Ni foil. The solder thickness ranges from 10 to 60 μm. We observe the microstructure of the intermetallic compounds (IMCs) growth on both side after reflow at 260℃ and aging at 150℃. The interfacial IMCs was indentified as (Cu,Ni)6Sn5 on the both interface. When the thickness of solder become thinner. The IMCs on the Cu/Sn2.3Ag interface becomes thicker. Yet, the IMC thickness on the interface of Ni/Sn2.3Ag decreases. The rate constant of (Cu,Ni)6Sn5 on the Cu/Sn2.3Ag interface is 0.21 μm/min, whereas it is 0.11 μm/min for the (Cu,Ni)6Sn5 on the Ni/Sn2.3Ag interface. For interfacial reactions during solid state aging at 150℃,the IMCs on the Cu/Sn2.3Ag interface are (Cu,Sn)6Sn5 and Cu3Sn , but only (Cu,Ni)6Sn5 on the Ni/Sn2.3Ag interface. When the thickness of solder decrease, we observe that the IMCs on the growth rate of the IMCs on the Cu/Sn2.3Ag interface become faster, but IMC on Ni/Sn2.3Ag interface growth rate is slower. The rate constant for the (Cu,Ni)6Sn5 on the Cu/Sn2.3Ag interface is 8.4 x 10-3 μm/(hr)1/2, and 4.1 x 10-2μm/(hr)1/2 for the Cu3Sn IMCs. The rate constant of (Cu,Ni)6Sn5 on the Ni/Sn2.3Ag interface is 2.5 x 10-2μm/(hr)1/2.