Experimental method of measuring C4 die bump temperature for electronics packaging

Recent trends in the semiconductor industry are driving a continuous increase in power dissipation, but require a lighter, more compact and thinner packaging technology. One of the concern areas is the increasing temperature of the C4 die bump. As the power continues to increase, the electrical current through the C4 die bump increases accordingly, resulting in increased bump temperature due to Joule self-heating and trace heating. This increased electrical current and temperature causes electro-migration failure of the C4 die bumps. In order to fully understand and avoid this failure phenomenon, we need to know the C4 die bump temperature. This has necessitated the development of a measurement method for the C4 die bump temperature. This paper discusses the methodology of measuring the C4 die bump temperature as well as results of our measurements. The experimental study includes variation of the bump current, the die power dissipation, and different enabling thermal solutions including natural convection and forced convection conditions. The experimental results show the effect of the Joule self-heating of the bump, the effect of the trace heating to the bump, the effect of the die heating and the effect of the bump and trace resistivity.