Microelectronic Encapsulant Material Assessment: A Security Point of View

Different materials such as metal, ceramic, and polymer have been used as an encapsulant to protect microelectronic devices from contamination, moisture erosion, radiation, and related environmental conditions. The recent development of high I/O density and high-speed microelectronic systems has placed more demand on the packaging encapsulant reliability, including extreme temperature reliability (up to 350°C), high thermal transportation, and low interstress. This paper will first review the encapsulant material and the fabrication process for high-reliability package encapsulant. This analysis will include to our knowledge the first evaluation of chip packing from a security perspective. The essential properties required for the encapsulant to meet the IC designs will be introduced since each discussed parameter can also be altered maliciously, reliability-related materials, formulas, and fabrication processes. By considering the existing encapsulant characterization methods, potential security vulnerabilities will be evaluated. Based on these findings, a taxonomy of encapsulant security issues is established, and six important security-related parameters are introduced. Moreover, a non-destructive material characterization countermeasure is introduced which can address these security concerns. Three non-destructive inspection methods, Fourier-Transform Infrared spectroscopy (FTIR), 2DX-Ray imaging, and THz-Time Domain Spectrum (TDS), will be used to characterize the material of counterfeit and authentic samples as a proof of concept.