Failure Analysis Approach on Intricate Redistribution Layer (RDL) Failures
Failure Analysis Approach on Intricate Redistribution Layer (RDL) Failures
Wednesday, October 7, 2026: 8:20 AM
Summary:
Redistribution layers (RDLs) are critical in advanced packaging, yet their fine pitch geometries and multi material interfaces make failure localization increasingly challenging during failure analysis. This paper presents two contrasting case studies that illustrate how electrical signatures guide the selection of an effective failure analysis approach for RDL related failures. The first case demonstrates how simulation referenced Comparative Time Domain Reflectometry (TDR) enables the non destructive localization of total electrical discontinuity (open) RDL defects prior to physical analysis. Correlation between measured and simulated waveforms facilitated targeted cross sectioning that confirmed RDL delamination and cracking as the root cause. The second case investigates leakage failure even after full decapsulation removed the RDL structure, traditionally limiting direct physical localization. A coordinated workflow integrating backside OBIRCH, layout correlation, topside infrared (IR) imaging, and optical inspection enabled successful identification of mechanically induced damage beneath former RDL bond pad locations. These case studies demonstrate a practical, electrically driven approach to failure analysis strategy selection. When combined with simulation references and multimodal correlation, this methodology improves diagnostic efficiency and preserves failure mechanism visibility, even when critical structures are no longer physically present.
Redistribution layers (RDLs) are critical in advanced packaging, yet their fine pitch geometries and multi material interfaces make failure localization increasingly challenging during failure analysis. This paper presents two contrasting case studies that illustrate how electrical signatures guide the selection of an effective failure analysis approach for RDL related failures. The first case demonstrates how simulation referenced Comparative Time Domain Reflectometry (TDR) enables the non destructive localization of total electrical discontinuity (open) RDL defects prior to physical analysis. Correlation between measured and simulated waveforms facilitated targeted cross sectioning that confirmed RDL delamination and cracking as the root cause. The second case investigates leakage failure even after full decapsulation removed the RDL structure, traditionally limiting direct physical localization. A coordinated workflow integrating backside OBIRCH, layout correlation, topside infrared (IR) imaging, and optical inspection enabled successful identification of mechanically induced damage beneath former RDL bond pad locations. These case studies demonstrate a practical, electrically driven approach to failure analysis strategy selection. When combined with simulation references and multimodal correlation, this methodology improves diagnostic efficiency and preserves failure mechanism visibility, even when critical structures are no longer physically present.