Board-Level Reliability of 3D through Glass via Filters During Thermal Cycling

This paper theoretically and experimentally assesses the board-level reliability of glass-based 3D Integrated Passive Device (IPD) with TGV-based inductor capacitor (LC) filters in thermal cycling test. Important failure modes such as wellknown solder joint cracking and TGV failure as well as other failure modes such as glass cratering are investigated in this work. Through finite-element modeling, initial reliability predictions are made using a Morrow-Darveaux approach for solder fatigue life. To predict glass cratering, a stress-based approach is used. In the second part of this work, reliability experiments are conducted on fabricated samples, demonstrating reliable 3D IPD glass packages. Failure analysis has found that solder joint cracking and glass cratering have occurred, but no TGV failures have occurred. The experimental results are also compared to numerical predictions. Then, for future designs, the models are used to analyze the impact of key material and design parameters on the experimentally observed failure modes. It is predicted that reducing the glass core thickness will improve solder fatigue life and help prevent glass cratering. Also, TGVs are recommended to be kept away from solder joints to prevent glass cratering. Stress buffering of the dielectric also improves the reliability, though less than glass core thickness. By developing and correlating a model specifically for these devices, this work, for the first time, enables accurate study and optimization of key design parameters for 3D glass IPD radio frequency (RF) devices to achieve high mechanically reliability, highperformance long term evolution band devices, with potentially smaller footprint and thickness compared to current LTCC counterparts.