Effect of EMC properties on the chip to package interaction (CPI) reliability of flip chip package

Epoxy molding compounds (EMC) are commonly applied to mitigate the thermo-mechanical reliability issue associated with the chip-to-package interaction (CPI) of LK/ULK applied flip chip packages. To understand the effect of EMC viscoelastic properties on the stress level induced on the bump, under bump and chip edge interconnects, a series of numerical simulations and reliability test using CPI test vehicles (TV) are carried out using 28/14/10nm process. The results showed that the higher storage modulus leads to lower stress level at the near bump and under bump interconnect layers, and enhanced CPI reliability. An improved approach based on phase lag (tan δ) value and stress relaxation is proposed to evaluate the performance of EMC materials. Our CPI TV thermo-mechanical test results shows good agreement to our newly proposed guide line. Additionally, we show that high modulus induced EMC/SR delamination can be effectively eliminated by increasing SR thickness.