Ultrasonic ribbon bonding has gained much attention due to the endeavor of achieving higher module performance in power electronic packaging. Among all the ribbon materials, Ag ribbon is a promising... Show More

Ultrasonic ribbon bonding has gained much attention due to the endeavor of achieving higher module performance in power electronic packaging. Among all the ribbon materials, Ag ribbon is a promising candidate due to its superior electrical properties. However, research which has reported the bonding of the ribbon on chip side is scant. Thus, in this study, the authors carried out bonding of the Ag ribbon on various types of metallized wafers to examine the feasibility of Ag ribbon, simulating the bonding scenario on the chip side in power modules. Results revealed that bonding of the Ag ribbon is feasible on those wafers metallized Ag on top. The authors also discussed the implications for the bondability of Ag ribbon with different types of metallization layers.

The article presents the results of studying the dynamics of changes in the porosity of two-component briquettes and pellets depending on the size of particles and the proportions of components in... Show More

The article presents the results of studying the dynamics of changes in the porosity of two-component briquettes and pellets depending on the size of particles and the proportions of components in the mixture using an optimized packing of spheres. Knowing the patterns of change in the porosity allows to optimize the strength of the briquette and pellets as well as to improve their behavior in the reduction processes in blast furnaces, steel making furnaces and in direct reduction reactors. A computation experiment based on heuristic simulation model was designed to study the change of the estimated porosity under increasing/substituting the number of larger spherical particles in the mixture of spheres. The results obtained made it possible for the first time to reveal the extreme nature of the change in the porosity of the briquette/pellet with the addition of larger particles, depending on the fractional composition of the briquette. The results obtained open up new opportunities for optimizing the placement of fine-grained materials in the charge of metallurgical furnaces.

Using exothermic sleeves allows to reduce the volume of the risers required in the casting of ferrous alloys, as well as the amount of metal used, and the costs involved. In this work, flat plates... Show More

Using exothermic sleeves allows to reduce the volume of the risers required in the casting of ferrous alloys, as well as the amount of metal used, and the costs involved. In this work, flat plates of nodular iron were casted and the effects of the shape and size of the risers were analyzed. For this purpose, risers with two configurations (with and without exothermic sleeves), three shapes (cylindrical, spherical, oval), and two relative sizes (100% volume and 60% volume) were considered. The mixture that would experience a thermite reaction with the highest temperature was defined. Experimental tests and computational simulations were performed, indicating that the spherical sleeves result in the lowest porosity in the risers and the pieces. It was also found that the risers with exothermic sleeves and 60% of the base volume used satisfy the feeding requirements and reduce the defects in the piece.