Formulation Design And Mechanism Study Of Interface Enhanced Anti-delamination Epoxy Molding Compound

In the early electronic packaging products,tin lead alloy plating was widely applied to improve the solderability.But the usage of lead in the electrical elements has a negative impact on the environment and human health,thus tin lead alloy plating technology is being repealed and replaced.The solderability of copper framework is poor because of its large contact resistance.Pre-plated frame is a good choice to help improving the solderability of the leadframe.Silver and nickel are both effective to improve the property.Considering comprehensive performance,it is find that nickel plated frame is more able to meet the needs of various customers.Nickel would be oxidized in the air and form a dense oxide film,which would remarkably reduce its welding ability.In order to extend the service life of the electrical elements,palladium and gold thin layers are plated on the nickel coating.Palladium plating is to prevent the diffusion of nickel and gold plating.The role of gold plating is to prevent the oxidation of the nickel coating.Nickel and nickel/palladium/gold plating frame are emerging metal leadframes with wide applications.However,the bonding strength between nickel coating and epoxy molding plastics is low.Molding components are prone to delamination thus reducing the service life of the electrical components.In this context,investigation on how to improve the adhesion strength between epoxy molding compound(EMC)and nickel plated frame is of great significance.In this thesis,based on a comprehensive analysis of variant components impact on the EMC performance,we selected a formulation FO as the basic formulation for modification and also for comparison.The electronic packaging products produced from formulation FO have great mechanical properties,physical properties and alao good thermal and electrical performance,while showing a very weak adhesion with nickel plated leadframe.Thus FO based EMC cannot meet the demand for a new generation of nickel plated frame packaging products.According to the chemical structure analysis of components in F0,we adjusted the type and dosage of epoxy resin,coupling agent,modifier,curing agent and other components,a preliminarily modified formulation F6 was determined showing certain adhesion ability with nickel plated leadframe.Then study on mechanism and further formulation modification based on F6 led to the invention of advanced formulations F11 and F17 with remarkably improved adhesion with nickel plated leadframe and also great comprehensive performance.Moreover,the mechanism and affecting factors on the adhesion strength and performance were discussed and suggested,which provided the theoretical basis and guidance for developing new generation EMC products.