Analysis of Geometry Parameter Effects of Die Attach Adhesives in a TSSOP Package

摘要

TSSOP package has found extensive applications in logic, analog, communication and optopelectronic products because of its thin/low profile, and affordable price. Although the manufacturing process and packaging materials are getting matured, assembly engineers are facing challenges as JEDEC level one at 260 degree C is being pursued as reliability target. To develop and find low stress molding compound has been the main focus to minimize package failures due to molding compound delamination from die top and die pad. The contribution of die attach adhesives to molding compound delamination has been realized but is not well studied. In this paper, the residual stress on molding compound in a typical TSSOP package was calculated with Finite Element Analysis (FEA) program. The compatability between materials properties of molding compound and die attach adhesives was studied. In particular, the geometry factors of die attach including die attach fillet size and bondline thickness was analyzed. The simulation results showed that the configuration of die attach adhesives contributed a noticable difference to the residual stress of molding compound. In some cases, geometrical (i.e. bondline and fillet size) variations generated higher stresses in molding compound than materials property variations.