Macro- and Micro-Deformation Behavior of Sintered-Copper Die-Attach Material

Macro- and micro-deformation properties of sintered copper die-attach material were evaluated. The macro-deformation properties are the properties, including the contribution of voids, and the micro-deformation properties are the properties, excluding the contribution of voids. Macro-deformation properties were evaluated by tensile tests at room temperature along with finite-element analysis (FEA). The specimens for these tests were made by sintering copper-oxide nano particles in the form of paste in a hydrogen atmosphere under low and high pressures. The micro-deformation properties were estimated by tensile test and FEA using a model that reproduces the micro-porous structure obtained from processing focused-ion beam scanning electron microscope data. The micro-stress/strain curve estimated for sintered copper was found to lie above the sintered silver and below the bulk copper. The porosity dependency of the macro-deformation properties of sintered copper was calculated using FEA models and the estimated micro-deformation property. The results obtained show that the macro-deformation properties of sintered copper are higher than those of sintered silver with similar porosity. This suggests that sintered copper die-attach material requires a lower sintering pressure than for sintered silver to achieve the same strength.