The Ni-rich Part of the Ni-P-Sn System: Isothermal Sections

Abstract

Due to the use of phosphorus-containing nickel substrates in microelectronics, understanding of their reaction with Sn-based solders and knowledge of the corresponding reaction products is highly important. Therefore the ternary Ni-P-Sn system was investigated experimentally using x-ray diffraction (XRD), scanning electron microscopy (SEM) + energy dispersive x-ray spectroscopy (EDX)/wavelength-dispersive x-ray spectroscopy (WDS), and differential thermal analysis (DTA). Sample preparation was done by alloying powders of the starting components contained in alumina crucibles in evacuated quartz tubes. In this study the phase equilibria in the Ni-rich part of the ternary Ni-P-Sn system are described in the form of three partial isothermal sections at 550°C, 700°C, and 850°C. A total of five ternary compounds exist in the Ni-rich part, and the binary Ni 3 Sn 2 HT phase was found to dissolve 17.6 at.% P at 850°C. This well agrees with literature reports, while a different extent and shape of the large homogeneity range of this phase were found. Between 850°C and 700°C phase equilibria change significantly due to the formation of the ternary phases Ni 10 P 3 Sn 5 (T3), Ni 13 P 3 Sn 8 (T4), and Ni 2 PSn (T5).

Ni-Rich Part of the System Ni-P-Sn: Thermal Behavior

“…The liquid composition was deduced from the DTA measurements in consistency with other phase diagram information. [1] Information from the DTA was further enhanced by metallographic investigations of the solidification behavior of a number of samples, with the focus on the primary crystallization. These results are shown in Table IV, in which the primary crystallization is indicated by an asterisk.…”

“…Recently, in a study from our laboratory, three partial isothermal sections from the Ni-rich part of the Ni-P-Sn system were presented [1] based on X-ray diffraction (XRD) and electron probe microanalysis (EPMA). In the present investigation, the results of thermal analyses in the same region will be discussed.…”

“…Together with three partial isothermal sections based on X-ray powder diffraction and electron probe microanalysis [1] (EPMA), a complete and consistent description of the Ni-rich part could be established. The Scheil diagram (reaction scheme), the liquidus surface, and three (partial) vertical sections (Ni 3 Sn -Ni 2 P, Ni 3 Sn -P, and Ni 3 Sn 2 -Ni 2 P) in the investigated composition range are presented in this study.…”

Interface Reaction Between Electroless Ni–Sn–P Metallization and Lead-Free Sn–3.5Ag Solder with Suppressed Ni3P Formation

“…According to the Ni-Sn-P phase diagram at 550°C, 16,17 formation of Ni 3 P will be avoided when the Sn concentration is greater than $10 wt.% ($5 at.%) and the P content is approximately 6-7 wt.%. Instead, the composition falls into the region of (Ni + Ni 3 Sn + Ni 21 P 6 Sn 2 ) at 550°C.…”

“…Instead, the composition falls into the region of (Ni + Ni 3 Sn + Ni 21 P 6 Sn 2 ) at 550°C. 16 Private communication with C. Schmetterer, the author of Refs. 16 and 17, revealed that the Ni-Sn-P phase diagram for temperatures below 550°C is not available because of practical difficulties.…”