Contact Resistance Stabilization for Lead Free Surfaces

Technology #3281

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Yi Li
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Kyoung-Sik Moon
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Ching Ping Wong
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Background: With the phasing out of lead-bearing solders, electrically conductive adhesives (ECA's) have been identified as a environmentally friendly alternative to tin/lead (Sn/Pb) solders in electronic packaging applications. Unfortunately, unstable contact resistance on non-noble surfaces due to galvanic corrosion have been a critical issue and have prevented their wide applications.

Technology: A modified electrically conductive adhesive has been developed using innovative corrosion inhibitors such as amino acid and dicarboxylic acid. Proposed corrosion inhibitors can act as a barrier between the metal surface when forming a film over the metal surfaces, and therefore prevents the metal corrosion.  The functional groups are either –NH2, which can form bonds by electron donation, or acidic groups, such as –COOH, which can provide the proton to catalyze the epoxy resin. Furthermore, the carboxylate ion can coordinate with the Sn ion and immobilize its migration property. By forming a barrier layer or a protection film on the Sn surface, or by forming a ring closure with Sn, the contact resistance of ECA's on the Sn and Sn alloy surface can be stabilized and the reliability of ECAs can be improved significantly. 

Potential Commercial Applications: This invention would be useful in the production of solid oxide fuel cells for a broad range of applications such as power generation, transportation, and military applications.  Solid oxide fuel cells are attractive for many applications due to the efficient and clean production of electricity from a variety of fuels while operating in a vibration-free and virtually noise-free manner. 

Benefits / Advantages:·  

  • Significantly enhances electro-catalytic activity and stability of the cathode
  • Overcomes the technical hurdle of high operating temperatures and the use of expensive materials of solid oxide fuel cells
  • Catalyst coating introduced in a cost-effective, single-step solution infiltration process
  • Development could lead to solid oxide fuel cells with excellent fuel flexibility and improved efficiency


  • Yi Li
  • Kyoung-Sik Moon
  • Ching Ping Wong 
The School of Materials Science and Engineering at Georgia Tech