Magnetic Alloy Plating with Hydroxymethyl-P-Tolylsulfone (HPT) Organic Additive

Additives play an important role in thin magnetic alloy electrodeposition since they impact the film grain boundary, the nucleation and growth mechanism. Consequently, they significantly determine the film properties.

In this study, we have evaluated a α-hydroxy sulfone compound as plating additive (Hydroxymethyl-P-Tolylsulfone or HPT was used as a case study) in CoNiFe and CoFe electrodeposition processes. From the chemical nature of HPT, the major drawback of this compound is its poor stability in aqueous medium in the presence of air. Analytical (HPLC) and electrochemical methods have been utilized to identify the compound decay mechanism and behavior. The HPLC spectrum of HPT and its decay by-products are compared to those of pure known compounds in Fig 1. With HPT added into CoNiFe and CoFe electrolytes, a strong grain refining effect was noticed in the deposits and the related film properties (magnetic, morphology and corrosion properties, etc.) have been characterized accordingly.