Study of flip-chip and beam-lead microcircuit assemblies

The paper evaluates and compares the flip-chip and beam-lead methods of making microcircuit assemblies, paying particular attention to thermal and mechanical considerations. The thermal studies indicate that the beam-lead and flip-chip approaches are similar for chips with many mounting points, and that the use of heat spreaders offers a considerable advantage. The use of a glazed ceramic substrate material is not recommended for glaze thicknesses greater than 10¿3in. The mechanical studies show that considerable forces can be set up when beam-lead and flip-chip assemblies are temperature-cycled. These forces can almost reach the ultimate shear or tensile strengths of gold with typical temperature changes.