SBIR-STTR Award

This Small Business Innovation Research Phase I project will develop a cost-effective novel Electroless Nickel Immersion Gold (ENIG) surface finish to achieve robust solder joints for better reliability of electronic assemblies. Currently available ENIG surface finishes are prone to so-called "black pads", which are sites of galvanic hyper corrosion that lead to failures associated with de-wetting of solder, brittle solder joints, component disconnection, and overall malfunction of electronic assemblies. Existing substitute surface finishes are either very expensive or do not resolve the black pad defects fully, and they can compromise other key properties. The cost-effective novel ENIG to be developed will eliminate black pads, corrosion related issues, achieve robust solder joints and provide improved quality & reliability of electronic assembly products to end consumers. This will allow manufacturers to avoid major product field failures and the resulting consequences. This new technology would be a potential replacement for existing ENIG (with a market value in excess of $400 million) and other surface finishes (representing a market exceeding $1 billion). The intellectual merit of this project includes development of a cost-effective novel ENIG to eliminate black pads and achieve robust solder joints. The root cause of black pad defects has been identified as hyper corrosion activity of the immersion gold process which originates at intergranular boundaries and crevices of the nickel-phosphorous surface. Galvanic hyper-corrosion occurs between gold and nickel atoms, resulting in nickel depletion and an enrichment of phosphorous atoms in the localized area. The proposed research would use an interfacial engineering approach at the gold and nickel-phosphorous interfaces to prevent black pads and eliminate brittle solder failures in the electronic assemblies. The main objective of the proposed Phase I research is to achieve marked improvement in corrosion resistance (eliminate black pads) and attain robust solder joints (eliminate brittle solder joint failures). This will involve identifying right interfacial chemistry and process parameters. Corrosion resistance of this new process will be evaluated using electrochemical corrosion tests and acid tests. In addition, solder joint strength and properties (brittle/ductile) will be investigated using ball shear tests and cold ball pull tests.

The Small Business Innovation Research (SBIR) Phase II project will scale-up development of eco-friendly, cost-effective novel Electroless Nickel Immersion Gold (ENIG) surface finish with high corrosion resistance and robust solder joints for better reliability of electronic assemblies. Conventional ENIG currently available in the market is prone to black-pad defects (hyper-corrosion related failures) associated with de-wetting of solder. ENIG also suffers from brittle solder joint failures. Due to these reasons, there are field failures and reliability concerns of electronic assemblies - component disconnection which lead to overall malfunction of electronic assemblies. Moreover, most ENIG manufacturers/suppliers provide cyanide-based gold chemistry which has health and ecological hazards. The novel ENIG eliminates black pads- corrosion related issues, achieves robust solder joints and provides improved quality and reliability of electronic assembly. Also, it uses cyanide-free chemistry for immersion gold process making it eco-friendly. This allows manufacturers to consume eco-friendly product while avoiding major field failures and resulting consequences. This new technology would be potential replacement for existing ENIG (with market value roughly about 2-3 billion USD/year). The primary focus of the project is to eliminate black-pad related failures and lead to robust, high quality and reliable solder joints for electronic assemblies. The root cause of black-pad defects has been identified as hyper corrosion activity at gold and nickel-phosphorous interface which involves nickel depletion and an enrichment of phosphorous in localized areas. During Phase I, interfacial engineering approach had been used to successfully eliminate black pads by achieving marked improvement in corrosion resistance. This has led to robust solder joints and elimination of brittle failures. In Phase II, the focus will be to scale-up development, optimize the product/chemistries and carry out further reliability testing. The main goal would be the rapid commercialization of novel ENIG into the market. This will involve development of the chemistries/process parameters for replenishing solution to make it market ready, economical and efficient for customers, further chemical testing for quality compliance (shelf life, quality standards, etc.) as well as reliability testing. Reliability testing will involve real world scenarios and various industry standard based testing including drop and vibration tests and solder ball shear and pull tests at extended thermal exposures.