TY - JOUR
T1 - The effects of electroplating parameters on the composition and morphology of Sn-Ag solder
AU - Kim, J. Y.
AU - Yu, J.
AU - Lee, J. H.
AU - Lee, T. Y.
PY - 2004/12
Y1 - 2004/12
N2 - The Sn-Ag solder was electrodeposited from a bath that basically is composed of tin sulfate (SnSO4), silver nitrate (AgNO3), and thiourea (CH4N2S), acting as a complexing agent to silver. The composition and morphology of electrodeposited Sn-Ag solder were studied in terms of silver concentration in bath current density, duty cycle, and additives. It was possible to control silver content in the electrodeposit by means of varying silver concentration in bath and current density. The microstructure and surface morphology of the electrodeposit become finer and smoother with increasing current density. The pulse-current (PC) plating method was applied to compare to the conventional direct-current (DC) plating. Varying duty cycle in PC plating did not change the microstructure in general, but some improvement in surface roughness was observed compared to DC plating. However, the silver composition in the electrodeposit increased with decreasing the duty cycle at a constant current density. An addition of a surface-active agent helped to reduce the surface roughness and the variation of silver content in the electrodeposit. In an optimum condition, eutectic Sn-Ag solder bumps with a fine pitch of 30 μm and height of 15 μm were successfully electroplated. The composition of Sn-Ag bumps was analyzed by energy dispersive x-ray spectrometry (EDS) and wavelength dispersive x-ray spectrometry (WDS) methods, and the surface morphology was characterized by scanning electron microscopy (SEM) and a three-dimensional surface analyzer.
AB - The Sn-Ag solder was electrodeposited from a bath that basically is composed of tin sulfate (SnSO4), silver nitrate (AgNO3), and thiourea (CH4N2S), acting as a complexing agent to silver. The composition and morphology of electrodeposited Sn-Ag solder were studied in terms of silver concentration in bath current density, duty cycle, and additives. It was possible to control silver content in the electrodeposit by means of varying silver concentration in bath and current density. The microstructure and surface morphology of the electrodeposit become finer and smoother with increasing current density. The pulse-current (PC) plating method was applied to compare to the conventional direct-current (DC) plating. Varying duty cycle in PC plating did not change the microstructure in general, but some improvement in surface roughness was observed compared to DC plating. However, the silver composition in the electrodeposit increased with decreasing the duty cycle at a constant current density. An addition of a surface-active agent helped to reduce the surface roughness and the variation of silver content in the electrodeposit. In an optimum condition, eutectic Sn-Ag solder bumps with a fine pitch of 30 μm and height of 15 μm were successfully electroplated. The composition of Sn-Ag bumps was analyzed by energy dispersive x-ray spectrometry (EDS) and wavelength dispersive x-ray spectrometry (WDS) methods, and the surface morphology was characterized by scanning electron microscopy (SEM) and a three-dimensional surface analyzer.
KW - Duty cycle
KW - Electroplating
KW - Morphology
KW - Pulse plating
KW - Sn-Ag solder
KW - Surface-active agent
UR - http://www.scopus.com/inward/record.url?scp=11344261886&partnerID=8YFLogxK
U2 - 10.1007/s11664-004-0087-9
DO - 10.1007/s11664-004-0087-9
M3 - Article
AN - SCOPUS:11344261886
SN - 0361-5235
VL - 33
SP - 1459
EP - 1464
JO - Journal of Electronic Materials
JF - Journal of Electronic Materials
IS - 12
ER -