【作者】 张毅；

【导师】 刘平；

【作者基本信息】 西安理工大学 ， 材料学， 2009， 博士

【摘要】 针对大规模集成电路对引线框架材料提出的性能要求,运用铜合金的微合金化原理成功研制和开发了三种新型高强度中导电Cu-Ni-Si系微合金化引线框架铜合金——Cu-2.0Ni-0.5Si. Cu-2.0Ni-0.5Si-0.15Ag和Cu-2.0Ni-0.5Si-0.03P合金,并对比研究了其时效析出特性、析出相结构、高温塑性变形行为及动态再结晶规律。对比研究了几种合金的时效析出行为和强化机理,探讨了微量合金元素Ag、P对Cu-Ni-Si合金析出强化特性的影响,研究发现：①固溶态Cu-2.0Ni-0.5Si合金在400～500℃进行时效时,时效初期其显微硬度大幅上升,且时效温度越高,显微硬度上升幅度也就越大,同时导电率迅速升高,且随着时效温度的提高,导电率增幅越大；时效前的预冷变形加速时效析出过程的进行。②微量合金元素Ag的加入有效的提高了合金的导电率,微量合金元素P的加入有效的提高了合金的显微硬度和抗拉强度,450℃时效2h后,0.15%Ag的加入,使显微硬度、导电率、抗拉强度分别提高2.1%、15.3%、8.7%；而0.03%P的加入,使显微硬度、导电率、抗拉强度分别提高18.6%、2.3%、29.8%。③TEM和HRTEM的分析结果均表明：Cu-2.0Ni-0.5Si、Cu-2.0Ni-0.5Si-0.15Ag合金时效析出强化,是由在铜基体上析出的Ni2Si相起到强化作用,Cu-2.0Ni-0.5Si-0.03P合金在时效过程中析出Ni2Si和Ni3P两种析出相起到强化作用。④在分析Cu-2.0Ni-0.5Si合金时效过程中导电率变化规律的基础上,利用合金时效过程中析出相的体积分数与导电率的线性关系,推导出试验条件下合金的Avrami相变动力学方程与导电率方程。采用第一性原理,利用密度泛函理论的广义梯度近似下的平面波赝势法(DFT-GGA-PWP),对Cu-Ni-Si合金析出相δ-Ni2Si的晶体结构、形成热与结合能、电子结构等进行了理论计算与分析。结果表明δ-Ni2Si是较为稳定的析出相,与TEM和HRTEM分析结果相吻合,这加深了对Cu-Ni-Si合金析出过程以及析出机理的理解,表明DFT-GGA-PWP方法也可应用于析出强化型铜合金析出相结构的分析和预测。本文在Gleeble-1500D热模拟试验机上,采用高温等温压缩试验,对Cu-2.0Ni-0.5Si、Cu-2.0Ni-0.5Si-0.15Ag和Cu-2.0Ni-0.5Si-0.03P合金在应变速率为0.01～5s-1、变形温度为600～800℃、最大变形程度为60%条件下的流变应力行为进行了研究。分析了实验合金在高温变形时的流变应力和应变速率及变形温度之间的关系。并研究了在热压缩过程中组织的变化。从流变应力、应变速率和温度的相关性,得出了该合金高温热压缩变形时的应力指数n,应力参数α,热变形激活能Q和流变应力方程。采用加工硬化率曲线(θ—ε),确立了Cu-2.0Ni-0.5Si-0.15Ag和Cu-2.0Ni-0.5Si-0.03P合金的动态再结晶(DRX)温度为T≥700℃。获得了合金动态再结晶发生的临界条件与变形条件之间的关系。得到了Cu-2.0Ni-0.5Si-0.15Ag和Cu-2.0Ni-0.5Si-0.03P合金动态再结晶动力学数学模型,模型与实验数据吻合较好。研究了Cu-2.0Ni-0.5Si-0.15Ag和Cu-2.0Ni-0.5Si-0.03P合金动态再结晶晶粒尺寸d与Z参数关系,从而建立了合金动态再结晶尺寸模型。在上述试验基础上,对Cu-Ni-Si合金引线框架材料的时效工艺进行了优化,优化的多级时效工艺为：900℃×1h固溶→40%冷变形→450℃×2h时效→40%冷变形→420℃、460℃下分别时效不同时间。经上述工艺加工处理后,三种合金在420℃时效0.5h后,合金的导电率和抗拉强度、抗软化性能等综合性能最佳,如Cu-2.0Ni-0.5Si-0.15Ag合金的导电率、抗拉强度、抗软化温度分别为：54.2%IACS、754.8MPa和475℃;Cu-2.0Ni-0.5Si-0.03P合金的导电率、抗拉强度、抗软化温度分别为：48.6%IACS、803.9MPa和475℃。其综合性能完全达到了集成电路用Cu-Ni-Si引线框架材料的主要性能要求。更多还原

【Abstract】 To meet the property requirements for large-scale integrated circuits of the lead frame materials,three kinds of new high-strength and medium-conductivity Cu-Ni-Si alloys were successfully developed by use of trace alloy principle for copper alloy such as Cu-2.0Ni-0.5Si,Cu-2.0Ni-0.5Si-0.15Ag and Cu-2.0Ni-0.5Si-0.03P alloys. The aging properties, precipitates structures, high-temperature plastic deformation and dynamic recrystallization behavior were comparatively studied.The aging behavior and strengthen mechanism were comparatively studied for the three alloys.The effect of addition trace elements Ag and P on the precipitation strengthening properties were studied.While the solid solution Cu-2.0Ni-0.5Si alloy aging at 400～500℃,the micro-hardness greatly increased at the early stage of aging.The higher the aging temperature,the higher the micro-hardness.The electrical conductivity rapidly increased at the same time and the higher the aging temperature,the higher the electrical conductivity.The cold rolling deformation before aging accelerated aging precipitation.The electrical conductivity was effectively increased by addition trace element Ag. The microhardness and tensile strength were effectively increased by addition trace element P. With the 0.15% Ag addition, the values of the microhardness, electrical conductivity and the tensile strength could increase 2.1%、15.3%、8.7% after aging at 450℃for 2h,respectively. With the 0.03% P addition, the values of the microhardness, electrical conductivity and the tensile strength could increase 18.6%、2.3%、29.8% after aging at 450℃for 2h,respectively.The Ni2Si was the precipitated phase to strengthen the Cu-2.0Ni-0.5Si and Cu-2.0Ni-0.5Si-0.15Ag alloys,the Ni2Si and Ni3P were the precipitated phases to strengthen Cu-2.0Ni-0.5Si-0.03P alloy on aging process by means of transmission electron microscope (TEM) and high-resolution transmission electron microscope (HRTEM) analysis. On the basis of analysising the changes of electrical conductivity for Cu-2.0Ni-0.5Si alloy,the Avrami phase transformation kinetics equation and electrical conductivity equation were derived by use of the linearity between electrical conductivity and volume fraction of precipitates under the aging process.The crystal structure,combining energy and power,electronic structure of 8-Ni2Si were studied by using the plane wave pseudo-potential method(PWP) with GGA and DFT of the first principle method for the first time.The result show thatδ-Ni2Si was a stable precipitate phase. The results deepened on the understanding of precipitation mechanism of Cu-Ni-Si alloy. The results also show that the DFT-GGA-PWP method can be used to analysis and forecast the structure of precipitating strengthen copper-alloy.The flow stress behaviors of Cu-2.0Ni-0.5Si,Cu-2.0Ni-0.5Si-0.15Ag and Cu-2.0Ni-0.5Si-0.03P alloys during hot compression deformation was studied by isothermal compression test with Gleeble-1500D thermal-mechanical simulator when the temperature from 600℃to 800℃and strain rate from 0.01s-1 to 5s-1 under maxium strain of 60%. The relationship between the flow stress,strain rates and deformation temperatures were studied.The microstructure of the experimental alloys were studied in the hot-compression procedure. Stress index n,stress scale parameter a, hot deformation activation energy Q,and constitutive equation were derived from the correlativity of flow stress,strain rate and temperature. The condition of dynamic recrystallizaiton (DRX) for the Cu-2.0Ni-0.5Si-0.15Ag and Cu-2.0Ni-0.5Si-0.03P alloys is T≥700℃by using plot of work-hardening rate versus strain (θ-ε) curves.The relationship between the critical condition of dynamic recrystallizaiton (DRX) and deformation condition was obtained.The DRX kinetic equation is submitted and the calculated fraction of DRX by using the model has good agreement with that of experiments. The relationship between the dynamic recrystallizaiton (DRX) grain size and the parameter Z was obtained.A dynamic recrystallizaiton (DRX) grain size model was obtained.Thg aging processes for Cu-Ni-Si lead frame alloy were developed based on the optimization of the process parameters.The multi-aging production process for Cu-Ni-Si alloy was as follow:solid solution at 900℃for 1h→40% cold rolling→aging at 450℃for 2h→40% cold rolling→aging at 420℃and 460℃.The electrical conductivity and strength have optimum combination after the alloy aged at 420℃for 0.5h.The combinations of electrical conductivity,tensile strength and soft temperatures were as follow: 54.2%IACS,754.8MPa and 475℃for Cu-2.0Ni-0.5Si-0.15Ag alloy respectively; 48.6%IACS,803.9MPa and 475℃for Cu-2.0Ni-0.5Si-0.03P alloy respectively. These properties can meet the requirements of high strength and high electrical conductivity copper alloy for lead frame.更多还原