Cu/Sn 瞬态液相扩散焊接(TLPS)接头多尺度结构与性能的协同控制

In order to meet the high-performance, low-cost high-temperature resistant lead-free solder demand and to solve the poor performance and low reliability of the high-temperature power electronic device die attaching joint, the technology of Cu/Sn composite powder pressure molding - transient liquid phase diffusion soldering to prepare the high temperature interconnect joint was proposed in this project, the strength, toughness and thermal stability of joints were strengthened through regulating multi-scale joint structure. The intermetallic compounds (IMCS) were used as skeletal phases strengthening Cu particles to regulate the interfacial structure, exploring joint strengthening properties discipline of the strength, thermal conductivity and electrical conductivity of the skeletal phase. The three-dimensional network structure regulation was strengthened by IMCS and Cu particles distribution, the synergistic control mechanism of multi-scale structure and strength was revealed..Through the online combined analysis and study on interface reactive kinetic, soldering process parameters and component ratios was controlled, the coupling law of diffusion mass transfer and interface reaction of Cu6Sn5/Cu3Sn/Cu system was revealed, the regulating mechanism of mass transmission and interface reaction to multi - scale joint structure is clarified. The inhibition mechanism of IMCS phase transformation was explored by Cu phase doping, the method of tissue and structure regulation of IMCS were established, the coordinate regulating discipline of multi-scale structure and joint properties was analyzed, an important theoretical basis for the preparation of high temperature joint using Cu / Sn system transient liquid phase diffusion soldering technology was provided.

为满足低成本、高性能耐高温无铅焊料需求，解决高温电力电子器件芯片互连接头性能差、可靠性不足的问题，项目提出Cu/Sn复合粉末压力成型-瞬态液相扩散焊接制备耐高温接头技术。通过调控接头多尺度结构，强化接头强度、韧性和热稳定性。通过界面金属间化合物（IMCS）形成骨架相调控Cu相界面结构，探索骨架相强化接头强度、导热导电性能规律；通过IMCS与Cu相分布强化三维网状结构调控，揭示多尺度结构与强度、韧性的协同控制机制。.通过在线联动分析及界面反应动力学研究，控制环境参数及物相组分，揭示Cu6Sn5/Cu3Sn/Cu体系扩散传质与界面反应的耦合规律，阐明扩散传质与界面反应对接头多尺度结构调控机制；通过Cu相掺杂改性，探索改性Cu对IMCS物相转变的抑制机制，建立IMCS结构和组织调控方法，解析多尺度结构协同调控接头性能规律，为Cu/Sn系统瞬态液相扩散焊接制备耐高温接头技术提供科学依据。

为满足低成本、高性能耐高温无铅焊料需求，解决高温电力电子器件芯片互连接头性能差 、可靠性不足的问题，项目提出Cu/Sn/Ag复合粉末压力成型-瞬态液相扩散焊接制备耐高温接头技术，通过调控接头多尺度结构，强化接头强度、韧性和热稳定性。通过Cu-Sn、Ag-Sn形成Cu3Sn/Ag3Sn骨架相调控Cu相界面结构，探索骨架相强化接头强度、韧性及导热导电性能规律，获得了Cu/Cu3Sn/Ag3Sn致密3D网络接头结构，在Sn层厚度为2µm的情况下，随着Ag层厚度增加，本体相的弹性模量和硬度逐渐降低，但热导率和电导率也随之降低。在Ag层厚度为1µm时综合性能达到最优，弹性模量和硬度分别为86.43GPa和1.79GPa，低于Cu/Sn体系的112GPa和2.63GPa，有效降低了本体相的刚度。在100 ~ 300℃温度范围内，Cu/Cu3Sn/Ag3Sn本体相的导热系数为130~145 W·m-1·K-1，电阻率为5.1μΩ·cm，相较于纯IMCs和高铅合金以及AuSn焊料具有更优异的导热和导电性能。通过Cu基板表面镀Sn和镀Ag等改性处理，互连接头界面处孔隙率降低。当Sn镀层厚度为2μm时接头的剪切强度最大，达到~45MPa，断裂路径为锯齿状，裂纹在基板与焊片界面处萌生后沿着焊片本体相中的Cu3Sn相以及Cu颗粒内部扩展，最终发生断裂。通过Cu/Sn/Ag体系TLPS焊接接头的多尺度结构和性能的协同调控，获得综合性能优异的耐高温接头，为Cu/Sn系统瞬态液相扩散焊接制备耐高温接头技术提供科学依据。

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