Accelerated Temperature Cycle Test and Coffin-Manson Model
for Electronic Packaging
Helen Cui, RF Micro Devices
Key Words: Accelerated Reliability Testing, Temperature Cycle, Coffin-Manson Model, Activation Energy
Product life could be significantly affected by the SUMMARY & CONCLUSIONS
maximum temperature (Tmax) the temperature change (∆T)
Temperature cycle profiles at various stress levels were dwell time and ramp rate. The larger of Tmax, ∆T, dwell investigated for accelerated reliability testing of electronic time, and ramp rate indicate the higher stress level. device packaging. Failure Analysis was conducted for test Temperature Cycling tests are used to characterize product failures to determine their root cause failure mechanisms and capability and to detect unknown failure modes (e.g., die failure modes. Weibull analysis was conducted for failures crack, via crack) during technology development, product with the main failure mechanisms (such as solder fatigue, design verification, and product qualification. mechanical cracks). The Coffin-Manson model has been used Often, the stress level of the test temperature profiles far to model crack growth due to repeated temperature cycling. A exceeds the product field application stress level. This leads to good correlation was obtained between the Coffin-Manson accelerated test. Test results at the high stress level need to be model and the test results, and Activation Energy (EA) was extrapolated to the low stress level, i.e., field application stress determined. The limitation and application of the Coffin-level. It is critical that the main failure mechanism remains
the same for the high stress level and low stress level. For Manson model are further discussed.
The main failure mechanism determined by failure new technology (or designs for which the field failure analysis was Via Cracking in the package substrate. The mechanisms are unknown) it is critical to conduct failure acceleration factor between different stress levels was analysis to determine root cause failure mechanisms and determined by Weibull analysis of test data. The Coffin-failure modes.
Manson model was used to correlate the test data and Temperature determine the activation energy related to via crack failure
mechanism. The Coffin-Manson model with determined
Activation Energy could be used to estimate product reliability
under different application conditions for the same main failure mechanism.
Today’s electronic packaging continues to shrink in size
and reaches higher packing density and higher reliability.
Accelerated test is needed to save test time and cost and ∆T
reduces cycle time to market. Various temperature cycling
profiles are employed to evaluate the effect of stress on life
and to detect the unknown failure modes. The temperature cycle profile can be characterized by
• High extreme temperature (Tmax), Figure 1 Temperature cycle profile schematic • Low extreme temperature (Tmin), • Temperature change ∆T, ∆T = Tmax - Tmin
• Ramp rates, In this study, a 6mm x 8mm electronic packaging module • Dwell times at extreme temperatures. with three die was tested with variety of temperature cycling profiles for accelerated tests. Via cracking was verified Figure 1 shows a schematic of temperature cycle profile. through temperature cycle tests. Weibull analysis was conducted on failures corresponding to the via crack failure