Nanosilver preform assisted die attach for high temperature applications

Using sintered silver as a high temperature die attach material has recently evoked much interest. The emergence of pressureless sintering using a silver nanoparticle based paste, however, has been of particular importance. Despite its numerous advantages and favorable properties, the die attach procedure using nanosilver paste has its share of problems. A reliable and repeatable process producing a strong and consistent bond is required, especially if a need arises to integrate this technology into high volume production. In this paper, a technique has been explored in which preforms made of nanosilver particles have been fabricated and used for die attachment. The preforms can be tailored to produce custom bond line thicknesses and can be cut to fit die spanning a range of different sizes. The die shear strength of a 1.5 mm x 1.5 mm Si die has been found to be 3.75 times larger using the proposed technique as compared to the conventional nanosilver process.