Quantitative TIM Coverage Analysis Using CSAM and 3D XRM for Advanced Packages
Quantitative TIM Coverage Analysis Using CSAM and 3D XRM for Advanced Packages
Wednesday, October 7, 2026: 9:20 AM
Summary:
Thermal Interface Materials (TIMs) are widely used to reduce thermal resistance and efficiently dissipate heat from high–power-density devices, such as CPUs, GPUs, and 3D stacked dies. Adequate TIM coverage is critical to filling microscopic gaps between components and heat sinks, thereby preventing thermal throttling and ensuring long term reliability in 2.5D and 3D integrated systems. Confocal Scanning Acoustic Microscopy (CSAM) is an effective technique for inspecting TIM coverage due to its high sensitivity to interfacial separations. However, in advanced packages - particularly those with cavity lids – Acoustic wave used in CSAM is unable to penetrate the cavities, limiting its ability to assess TIM coverage. As an alternative, 3D X ray Microscopy (XRM) has been employed to evaluate TIM coverage, but it presents significant challenges when imaging the low density organic materials commonly used in TIMs. In this paper, a quantitative comparison of TIM coverage inspection using CSAM and 3D XRM is presented for advanced packaging devices. An image processing algorithm was developed to enable void segmentation and coverage calculation for both techniques. A correlation between these two techniques is established, enabling reliable TIM coverage assessment across a broader range of advanced package devices.
Thermal Interface Materials (TIMs) are widely used to reduce thermal resistance and efficiently dissipate heat from high–power-density devices, such as CPUs, GPUs, and 3D stacked dies. Adequate TIM coverage is critical to filling microscopic gaps between components and heat sinks, thereby preventing thermal throttling and ensuring long term reliability in 2.5D and 3D integrated systems. Confocal Scanning Acoustic Microscopy (CSAM) is an effective technique for inspecting TIM coverage due to its high sensitivity to interfacial separations. However, in advanced packages - particularly those with cavity lids – Acoustic wave used in CSAM is unable to penetrate the cavities, limiting its ability to assess TIM coverage. As an alternative, 3D X ray Microscopy (XRM) has been employed to evaluate TIM coverage, but it presents significant challenges when imaging the low density organic materials commonly used in TIMs. In this paper, a quantitative comparison of TIM coverage inspection using CSAM and 3D XRM is presented for advanced packaging devices. An image processing algorithm was developed to enable void segmentation and coverage calculation for both techniques. A correlation between these two techniques is established, enabling reliable TIM coverage assessment across a broader range of advanced package devices.