Characterization of Nanosilver Dry Films for High-Temperature Applications

Identifying the Development State of Sintered Silver (Ag) as a Bonding Material in the Microelectronic Packaging Via a Patent Landscape Study

“…Unlike Ag joint formed from Ag paste, the die shear strength of the Ag joints formed from Ag laminate did not depend on the joint thickness and area [15]. Furthermore, the degradation of die shear strength of the Ag laminated joint after thermal cycling test could be reduced easily by increasing the thickness of the die attach materials to more than 50 lm [15]. Others demonstrated that Ag nanoporous sheet can be sintered on the electroless nickel/immersion gold (ENIG) finished Cu disk without any cleaning flux to produce a Ag joint of similar strength as the Pb-5Sn joint [42].…”

“…Comparison of reliability between pressureless and pressure sintered Ag joint needs to consider the die size because a large die limits the access of oxygen to pyrolyze the binders in the Ag paste under the central region of the die [11]. Figure 3 shows the die shear strength of pressureless and pressure sintered Ag joints for different die sizes after thermal aging at between 250 C and 300 C [14][15][16][17][18][19][20]. At similar die sizes and duration of thermal aging, the pressure sintered Ag joints showed higher die shear strength than pressureless sintered Ag joints.…”

“…The use of Ag laminate was reported as early as 1987 in a patent by Siemens [36], and this approach had been pursued by others [32,[37][38][39][40][41]. Unlike Ag joint formed from Ag paste, the die shear strength of the Ag joints formed from Ag laminate did not depend on the joint thickness and area [15]. Furthermore, the degradation of die shear strength of the Ag laminated joint after thermal cycling test could be reduced easily by increasing the thickness of the die attach materials to more than 50 lm [15].…”

“…12 was pioneered by Alpha Metals [104]. After the wafer-sawing step, a thermalheated flip-chip bonder picks up the sawn dies and able to laminate or stamp the sawn dies on the nano-Ag sheets because of the adhesiveness of the Ag film in the presence of the heated bonder [15]. Then the bonder will die-place and pressure-sinter the Ag-laminated dies one by one on specific locations of the substrate.…”

“…12. Figure 14 shows a typical sintering profile and the microstructure of the sintered Ag joint produced by this route [15]. The main advantage of this route is the ease of switching to different die sizes within one power module or package.…”