Lead-free TQFP package achieved JEDEC level 1/260°C by specific combination of die attach adhesive and leadframe

The continuing drive toward lead (Pb)-free electronics necessitates the development of a semiconductor package able to withstand the rigors of reflow at 260°C, to accommodate the Pb-free solders currently available. Three die attach materials with different chemistries; epoxy, acrylate and a proprietary hybrid chemistry, were evaluated on surface-roughened NiPdAu plated (TN-P.P.F.^®) leadframes. The die attach performance was compared to Cu, Ag and conventional NiPdAu-plated leadframes. The die shear test results revealed the roughened NiPdAu leadframe significantly improved interfacial adhesion across all die attach materials examined in this study. Surface structure and topography studies indicated that the excellent adhesion mainly arises from mechanical interactions. MSL results obtained from 14×14 mm TQFP leadframe packages indicated that the ultimate package performance was determined by a combination of the properties of both leadframe and die attach materials.