High‐Temperature Degradation Mechanism of Interfacial Thermal Resistance Based on Submicron Silver Adhesion

Abstract

heat transfer performance of TIM, and the test methods normally include two categories: steady-state and transient methods. However, the present ITR testing methods still suffer from sample damage and low accuracy. [4] Thus, a non-destructive ITR testing method with high accuracy is urgently needed, which is critical for promoting the development of TIM.Submicron silver has become a promising TIM owing to its high thermal conductivity and strong adhesion, which can greatly reduce the ITR. [5][6][7][8] However, the thermal reliability of the silver-adhesive interface is still a major issue. Numerous studies focused on the degradation of properties, such as mechanical strength, material oxidation, and electrochemical corrosion through the test of high temperature, high humidity, and temperature cycling. [9][10][11][12][13][14] Liu et al. reported that conductive adhesive would undergo further curing, hydrolysis, and oxidation under high temperature and humidity, but it did not provide in-depth theoretical explanations. [15] Lin et al. found that the hydrothermal environment induced the hygroscopic expansion of epoxy resin and weakened the absorption peak of the epoxyfunctional group by Fourier transforming infrared (FTIR) spectrum analysis. [16] Several studies hypothesized that the number, size, and shape of porosity would interrupt the interface thermal conduction path, and thus, decrease the equivalent thermal conductivity. However, the evolution of porosity during the aging process is not investigated. [17][18][19] Skuriat studied the change in micro-morphology under high-temperature aging of Thermal interface materials (TIM) represented by submicron silver adhesive provide a promising solution for ultra-high heat dissipation in chip integration. However, it is difficult to accurately characterize the thermal performance of submicron silver adhesive interfaces, and their high-temperature degradation mechanism still remains unclear. Herein, the accelerated high-temperature aging experiments of submicron silver adhesion interfaces are performed, and a non-destructive testing method is provided to measure the degeneration of interfacial thermal resistance (ITR). After performing the two-sided test, ITR can be extracted with an error of less than 4.6%. Based on scanning electron microscopy and X-ray microstructural analysis, the microstructural evolution of silver adhesive interfaces is presented and its high-temperature degradation mechanism is determined. It is observed for the first time that ITR would change with the aging time following a bathtub curve. Such a degenerative process can be evidently divided into three stages including secondary solidification, fluctuation, and failure. In addition, a physical model is developed to interpret the degradation mechanism of ITR at high temperatures. The change in the trend of submicron silver body and TIM-solid contact thermal resistance at different stages is presented. This work helps promote submicron silver's application as high-performance TIM.

Carbon–Carbon Composite Metallic Alloy Joints and Corresponding Nanoscale Interfaces, a Short Review: Challenges, Strategies, and Prospects

“…To date, the joining methods of C/C composites mainly include mechanical joining [9,10], adhesive bonding [11][12][13][14], brazing [15][16][17][18][19], diffusion joining [20,21], and hightemperature self-propagation reactions. There are two problems with forming mechanical joints by using the difference in roughness between the C/C composite and the material to be joined.…”