Reliability evaluation of 3D-package with specific test structures

This paper reports the test structures used to evaluate and characterize the reliability of flip-chip joints by using soldering or adhesives. In addition, one multifunctional test die has been designed and fabricated using a 3M/2P CMOS process. The test die (size 4.87/spl times/4.87 mm/sup 2/) can be used to characterize interconnections on rigid or flexible substrates. Structures in addition to daisy-chain include heaters, temperature sensors (diode-connected transistors), strain-gauges, moisture sensors, current driving structures and bump offset structures. Measurement structures are connected to the PWB via the most reliable FC-joints. Furthermore, some heaters, temperature sensors, and strain gauges connections can be done via wire-bonding. The test die can be used to characterize the reliability of a 3D system-on-package. In this approach, thicknesses for PWBs of around 160 /spl mu/m and for test dies of 90 /spl mu/m were selected. Heaters and temperature sensors are to play an important role checking thermal management properties of the 3D-module.