Electroless deposition of Ni–P/Au coating on Cu substrate with improved corrosion resistance from Au(iii)–DMH based cyanide-free plating bath using hypophosphite as a reducing agent

In the Au(iii)–DMH based cyanide-free electroless gold plating bath, the added hypophosphite inhibited the black pad and improved the corrosion resistance of the Cu/Ni–P/Au coating.

Electroless Ni plating solutions for reproducible black pad analyses.

A large-scale black pad of electroless nickel (EN) plated films were reproduced using pure chemicals: NiCl2·6H2O as the Ni source, NaH2PO2·H2O as the reducing agent, CH3COONa·3H2O and aminoacetate as the complexing agent and the buffer, respectively, and thiourea as the stabilizer. Plating baths with varying constituent compositions were investigated, and chemical compositions most suitable to the black pad study were sought. Cross-sectional scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses showed that the nickel-phosphorus (Ni-P) film made out of the #5 bath best demonstrated the typical characteristics of the black pad phenomenon after the immersion gold (IG) process. Additions of a low level of Thiourea (0.6mg/L), slightly larger amounts of glycine (1∼1.25x) and the complexing agent (1.25x) were suggested from the standpoint of the black pad formation of Ni-P films.

PCB Related Failures in Electronic Assemblies

The complexity of Printed Circuit Boards (PCBs) has increased dramatically over the last three decades with the development of surface mount technology (SMT). The typical manufacture of rigid multilayer PCB contains many process procedures, which makes manufacture and application much more challenges. This paper focuses on some typical PCB related failures. Recommendations are provided on optimizing PCB manufacture process and material application. Microvia crack, black pad, galvanic attack, pad design, conductive anodic filament and pad crater are presented in detail.