Transmission Electron Microscopy of Joints between the Sn-Ag Solder and the Electroless Ni-P of an Electronic Device

Abstract

Microstructure of Pb free Sn Ag solder and joints between the Pb free solders and electroless Ni P was examined by means of transmission electron microscopy. Microstructures of the solders consist of b Sn matrix dispersed with Ag 3 Sn particles. Analysis of the diffraction patterns shows that there are more than one orientation relationships between b Sn and Ag 3 Sn. The solder joint of the Pb free solders is essentially similar to the joint of Pb Sn eutectic solders. Analysis of distribution of the elements by EDX analysis shows that Ag does not diffuse into Ni P. Both of the as deposited Ni P and P enriched Ni, the latter being formed as a result of reaction with Sn Ag solder, have FCC structures based on pure Ni. In other words, P is dissolved in Ni to form a solid solution.

Three-dimensional analysis of the interface between an Sn-8wt.%Zn-3wt.%Bi solder and a substrate by using an angle-lapping method

“…Using TEM, it is possible to analyze the microstructure formed during soldering. 7,8 However, generally speaking, a multilayer structure, which might include the boundary of a solder and a substrate, could be analyzed only in the crosssectional direction even though it might have an anisotropic structure.…”

Transmission Electron Microscopy of Interfaces in Joints between Pb-Free Solders and Electroless Ni-P

“…However, recently a novel technique, a focused ion beam (FIB) technique, has been successfully applied to preparing a TEM foil specimen of a solder joint. [3][4][5][6] Matsuki, Ibuka and Saka 6) carried out a comprehensive analysis on the microstructure of Pb-Sn eutectic solder joints. More recently TEM observations of Pb-free solders have been carried out by Kariya et al 7) However, their observations did not clarify the detailed structure of the solder joints.…”