Browsing by Author "Lin, K. S."

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Interfacial reaction between Sn-1Ag-0.5Cu(-Co) solder and Cu substrate with Au/Ni surface finish during reflow reaction
(2009-03-05)
Lin, K. S.
;
Huang, H. Y.
;
Chou, C. P.
;
機械工程學系
;
Department of Mechanical Engineering
In order to clarify the effect of the addition of Co to SAC105 solder, the reaction between solder and Au/Ni surface finish has been investigated, and the joint strength was also evaluated by a ball shear test. After soldering, the interfacial reaction layer in the SAC105 Co solder contained Co, and the chemical composition of intermetallic compounds (IMCs) were identified as (Cu,Ni,Co)(6)Sn(5) and (Ni,Cu,Co)(3)Sn(4) by energy-dispersive X-ray spectrometer (EDX), which significantly differed from that of SAC105 solder. After multiple reflows, the formation rate of the (Cu,Ni,Co)(6)Sn(5) IMC for the Co-added solder slow compared with that of (Cu,Ni)(6)Sn(5) IMC for SAC105 solder. Experimental results clearly indicate that adding small amounts (0.05 wt.%) of Co to SAC105 solder strongly affected the formation of the IMC at the interface. Furthermore, ball shear test results demonstrate that the SAC105 and SAC105 Co solder joints have good joint reliability. (C) 2008 Elsevier B.V. All rights reserved.
Interfacial Reactions and Bonding Strength of Sn-xAg-0.5Cu/Ni BGA Solder Joints
(2009-03-01)
Lin, K. S.
;
Huang, H. Y.
;
Chou, C. P.
;
機械工程學系
;
Department of Mechanical Engineering
The present study details the microstructure evolution of the interfacial intermetallic compounds (IMCs) layer formed between the Sn-xAg-0.5Cu (x = 1, 3, and 4 wt.%) solder balls and electroless Ni-P layer, and their bond strength variation during aging. The interfacial IMCs layer in the as-reflowed specimens was only (Cu,Ni)(6)Sn(5) for Sn-xAg-0.5Cu solders. The (Ni,Cu)(3)Sn(4) IMCs layer formed when Sn-4Ag-0.5Cu and Sn-3Ag-0.5Cu solders were used as aging time increased. However, only (Cu,Ni)(6)Sn(5) IMCs formed in Sn-1Ag-0.5Cu solders, when the aging time was extended beyond 1500 h. Two factors are expected to influence bond strength and fracture modes. One of the factors is that the interfacial (Ni,Cu)(3)Sn(4) IMCs formed at the interface and the fact that fracture occurs along the interface. The other factor is Ag(3)Sn IMCs coarsening in the solder matrix, and fracture reveals the ductility of the solder balls. The above analysis indicates that during aging, the formation of interfacial (Ni,Cu)(3)Sn(4) IMCs layers strongly influences the pull strength and the fracture behavior of a solder joint. This fact demonstrates that interfacial layers are key to understanding the changes in bonding strength. Additionally, comparison of the bond strength with various Sn-Ag-Cu lead-free solders for various Ag contents show that the Sn-1Ag-0.5Cu solder joint is not sensitive to extended aging time.