Leadframe Material, Design and Surface Treatment for MSL 1 260°C Package Robustness

Microelectronic packages and assemblies typically consist of layers of materials with dissimilar properties. Thermally induced stress in such multilayered structures could reach significant levels near the free edges, leading to interface de-bonding or delamination, and thus resulting in failure of the multilayered structure. A significant amount of studies has been conducted on this bonded layer integrity. The metal based leadframe in microelectronic packages is still the most widely used in the semiconductor industry. It makes up the largest portion of materials cost in plastic packages; especially for quad flat leadless (QFN) packages. In selecting the type of leadframe substrate material, characteristic such as strong structure that can withstand handling, yet compliant to bending must be met. They must also have high thermal conductivity to dissipate heat generated by the IC and good electrical properties so as not to compromise its electrical performance. In addition, leadframes are a critical part of the reliability of the overall packaging system.