Intermetallic Reactions in Reflowed and Aged Sn-58Bi BGA Packages with Au/Ni/Cu Pads

Abstract

The reflow of Sn-58Bi solder joints in a BGA package with Au/Ni/Cu pads has been performed by employing various temperature profiles, which results in the formation of (Au 0.66

Effect of La addition on the interfacial intermetallics and bonding strengths of Sn–58Bi solder joints with Au/Ni/Cu pads

“…The appearance of Ni 3 Sn 4 intermetallic phase at the interfaces of Ni electroplated pads with Sn-58Bi and Sn-58Bi-0.5La solders is consistent with previous results for the interfacial reactions between Sn-58Bi solders and Ni substrates [10][11][12][13]. However, the (Au 0.3 Ni 0.7 )(Sn 0.9 Bi 0.1 ) 4 /Ni 3 Sn 4 double layers as reported by Chi et al [14] at the interfaces of Sn-58Bi solder joints with Au(0.5 m)/Ni(5 m)/Cu pads were not found in the present study. The absence of a (Au 0.3 Ni 0.7 )(Sn 0.9 Bi 0.1 ) 4 intermetallic layer on the Ni 3 Sn 4 phase is attributed to the very thin Au film (0.1 m) on the Ni/Cu pads.…”

“…The intermetallic phases after interfacial reactions between Sn-58Bi solders and Ni substrates have been analyzed by many researchers [10][11][12][13][14]. Chen et al studied the thermal aging of Sn-58Bi solder joints at 85, 100 and 120 • C, and reported that a Ni 3 Sn 4 intermetallic phase formed at the interface [10].…”

“…The morphology of intermetallics as observed was scallop-shaped, and its growth kinetics exhibited a diffusion-controlled mechanism with an activation energy of 28.3 kJ/mol. Chi et al further studied the intermetallic reactions in reflowed and aged Sn-58Bi solder BGA packages with Au(0.5 m)/Ni(5 m) surface finished Cu pads [14]. Double layers of intermetallic compounds with compositions of (Au 0.3 Ni 0.7 )(Sn 0.9 Bi 0.1 ) 4 /Ni 3 Sn 4 were found at the solder/pad interfaces.…”

Drop Reliability of Epoxy-contained Sn-58 wt.%Bi Solder Joint with ENIG and ENEPIG Surface Finish Under Temperature and Humidity Test

“…EDS analysis identified that the chemical composition of the new IMC was approximately 65.35 at.% Sn, 15.95 at.% Bi, 9.20 at.% Ni, and 9.50 at.% Au, corresponding to (Au,Ni)(Sn,Bi) 4 phase. [23][24][25] These IMCs grew with increasing aging time. In the case of the ENEPIG surface finish, the dissolved Au formed Sn-Au-Pd IMCs that precipitated out of the solder during solidification and formed flake-shaped IMCs during reflow.…”

Comprehensive Properties of a Novel Quaternary Sn-Bi-Sb-Ag Solder: Wettability, Interfacial Structure and Mechanical Properties

“…Currently, the developed low-temperature solders are mainly selected from the Sn-Bi, Sn-In or Sn-Zn series [4]; but Sn-Bi solder provides the most potential due to its low cost and better comprehensive properties [5].The Sn-Bi binary solder system can reach the low eutectic temperature at 138 • C with a composition of Sn-58Bi, which provides the ideal processing temperature. However, there still exists some serious concerns on the application of Sn-58Bi eutectic solder, such as the interfacial embrittlement in solder joints [6][7][8][9], poorer drop reliability [10], the deterioration on joint strength after aging service [11], etc. All these problems are mainly attributed to the inherent embrittlement of Bi atoms.…”