New nanoscopic materials to mitigate growth of tin whiskers from lead-free solders

30-Sep-08

The pioneer of POSS® (Polyhedral Oligomeric Silsesquioxanes) - Hybrid Plastics under sponsorship from The National Science Foundation, Electronics Division, has unveiled a first landmark conformal coating, POSS® Short-Stop which is capable of suppressing tin whiskers from lead free solders and interconnects. The conformal coating is optically transparent, colorless and available as a sprayable coating for application to OEM and repair of electronic circuits. The new coating may go a long way to prevent short circuits that cause electronic systems to malfunction or become permanently damaged conductive tin whiskers grow long enough on lead solders and interconnects. The new materials were developed under a Small Business Innovation Research (SBIR) contract between Hybrid Plastics Inc., subcontractor Michigan State University and collaborator Vista Engineering. The solution was enabled through incorporation of mercapto functionalized Polyhedral Oligomeric Silsesquioxane (POSS) nanocages into polyimide coatings. The mercapto groups bind to the metal surface, protonate through the metal oxide layer and bind to the underlying tin atoms thereby mitigating compressive stress and nucleation of whisker growth. In the event that tin whiskers do grow, a tough high modulus polyimide surface coating is also utilized to force collapse of the whisker and thereby physically isolate whiskers against short-circuiting or detachment. POSS® is a revolutionary new Nanotechnology based on silicon-derived building blocks that provide nanometer-scale control to dramatically improve the thermal and mechanical properties of traditional polymers while offering easy incorporation using existing manufacturing protocols. These compounds have an average diameter of just 1.5 nanometers, or billionth of a meter. POSS® nanomaterials can be used both as direct replacements for hydrocarbon based materials or as low-density performance additives to traditional plastics. They release no VOCs, and, thereby, produce no odor or air pollution and are biocompatible, recyclable, non-flammable, and competitively priced with traditional polymer feedstocks.