Comment on the paper "Controlling intermetallic compound formation reaction between Sn and Ni-P by Zn addition" by X.F. Zhang, J.D. Guo, J.K. Shang, J. Alloys Compd. 479 (2009) 505-510

Zhang et al. recently reported about the formation of Ni4(Sn,Zn) in the interlayer of a Sn-Zn/Ni(P) solder joint. This phase is claimed to be based on the binary Ni4Sn phase. However, this phase as described in the literature by Mikulas and Thomassen, was ruled out for any existing phase diagram version. It could be proved that the diffraction pattern from Mikulas and Thomassen was composed of Ni and Ni3Sn low-temperature phase. Thus the interpretation of their X-ray diffraction results is incorrect and the phase "Ni4Sn" is an artefact. The indexing of Ni4(Sn,Zn) by Zhang et al. is based on this artefact and therefore is incorrect, too. Furthermore, Tai et al. investigated IMC formation in Sn-3Ag-0.5Cu/Ni-8Zn-8P joints and could not observe any interdiffusion of Zn as stated by Zhang et al.