Signal Delay Based Temperature Determination for Production Testing of Advanced Packages

This paper describes a technique to determine electrical test temperature of devices made of conventional packages like QFP and BGA as well as new packaging technologies such as system-in-package (SIP) and wafer level packages. It is based on the signal propagation delays that are sensitive to temperatures within the chip. The technique was applied to a QFP device, fabricated in 0.35 micron technology, that operates at 25 MHz with an average power consumption of about 0.5 Watt. The package geometry and the test environment have been numerically modeled. The signal delay measurement results are found to agree with the estimates based on numerical modeling. This technique will be useful in direct evaluation of production test temperatures when the package geometry and test environment are harder to model.