MATERIALS TRANSACTIONS
Online ISSN : 1347-5320
Print ISSN : 1345-9678
ISSN-L : 1345-9678
Effects of Complexing Reagent on Electroless Nickel Iron Alloy Plating for the Diffusion Barrier of UBM
Ja-Kyung KooJae-Ho Lee
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JOURNALS FREE ACCESS Advance online publication

Article ID: MA201606

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Abstract

Electro and electroless nickel platings have been extensively used as a diffusion barrier in under bump metallization (UBM) or as a surface finish on printed circuit boards (PCB). Even though a thin Ni layer on top of Cu can reduce the interfacial reactions with Sn-rich solders at a low reflow temperature, it may not be so effective when a reflow process is performed at a higher temperature and for a longer period. To provide a more robust diffusion barrier layer than electrodes Ni, electroless NiFe alloy system has been proposed. Since the electroless Ni-Fe plating bath has been rarely studied, the proper baths were not available commercially. In this research, the electroless plating of Ni-Fe alloys was investigated on the basis of complexing reagent. The stability of complexing reagent was studied. The compositions of electroplating layers were analyzed with EDS. The desired Ni-Fe alloy were obtained by controlling the chemical composition of the bath and its operating parameters.

Fig. 4 Surface morphologies of NiFe at different pH (a) pH8, (b) pH9, (c) pH10, (d) pH11, (e) pH11.5. Fullsize Image
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