Ionic contamination in the component materials of IC packages

IC packaging has always required that its components have little or no ionic contamination. This is necessary to avoid any corrosion issues within the package. This, in turn, has pushed the materials suppliers for the packaging industry to ensure that their products are free of contamination. Suppliers of materials ranging from leadframes and substrates to die attach adhesives and molding compounds have measured and reported their ionic contamination levels. They have, however, used their own specific methods and there has, up to now, been no standard for these tests. One of the reasons for a lack of standards is the fact that some of the materials such as die attach and mold compound have contamination levels that can be measured with respect to unit volume or weight of the material. Leadframes and substrates, on the other hand, have surface contamination and so the contamination levels are measured over their surface area. Yet another reason for a lack of standards is the variety of preparation methods employed within the industry. In this study, we measure the contamination levels in a range of IC packaging materials. These include varieties of leadframes, substrates, die attach and encapsulants. Methods for comparison are discussed while the specific details for sample preparation are given