【作者】 张波；

【导师】 刘桂武；

【作者基本信息】 江苏大学 ， 材料加工工程， 2016， 硕士

【摘要】 高体积分数(≥50%)SiC颗粒增强铝基复合材料(SiC_p/Al)在电子封装领域具有非常广阔的应用前景,有望完全替代目前使用的可伐合金成为新一代的电子封装材料。然而,由于其增强体与基体之间巨大的物理力学性能差异,使得高体积分数SiC_p/Al复合材料的连接具有较大困难。虽然熔化焊、扩散焊、瞬间液相连接和钎焊等方法在一定条件下都能实现对高体积分数SiC_p/Al复合材料的连接,但是目前还没有一种方法能够纯熟应用。钎焊由于加热温度较低,且钎焊后材料变形、残余应力小,因此在连接高体积分数SiC_p/Al复合材料上更具有潜力。本文以70vol.%SiC_p/Al复合材料为研究对象,制备了不同Mg含量的Al-Cu-Si-Mg(Al-20Cu-6Si-x Mg,x=0、1、3、5,质量比)钎料,并对该钎料的显微组织、熔化特性、物相、耐腐蚀性、拉伸强度等性能进行了测试分析,考察了自制Al-Cu-Si-Mg钎料和商用Sn-3.5Ag-0.5Cu钎料对70vol.%SiC_p/Al的润湿性、钎焊及其界面与接头性能。研究结果表明:Mg能够与Al形成低熔点共晶而降低钎料熔点,该四种Al基钎料的固相线温度分别为516.8°C、506.8°C、504.8°C和503.9°C,液相线温度分别534.3°C、531.9°C、529.8°C和531.4°C。Al-Cu-Si钎料主要由α(Al)基体、Al2Cu和Al2Si组成,而Al-Cu-Si-Mg钎料主要由α(Al)基体、Al2C u、Al2Si和Mg2Si组成。由于Mg2Si具有良好的固溶强化作用,固溶处理后钎料的拉伸强度显著提高,最高达到了308.6 MPa。由于钎料中Mg2Si的溶解比氧化膜的形成更快,所以Mg含量越高,氧化膜变薄,从而降低钎料的耐腐蚀性。对四种Al基钎料在SiC_p/Al复合材料上的润湿性测试表明,Mg能够去除钎料和母材表面的氧化膜,提高钎料在母材上的润湿性。含Mg量为1%、3%、5%的Al-Cu-Si-Mg钎料在SiC_p/Al复合材料上的接触角分别为143.7°、132.6°和125.5°。对Sn-3.5Ag-0.5Cu钎料在镀镍前后SiC_p/Al复合材料上的润湿性测试发现,Sn-3.5Ag-0.5Cu几乎完全不润湿SiC_p/Al复合材料,而对镀镍后SiC_p/Al复合材料表面具有良好的润湿性,即在400°C时的接触角为19.4°。在580°C时,四种Al基钎料钎焊未镀镍SiC_p/Al复合材料获得的钎焊接头的剪切强度分别为25.3、33.6、36.3和40.7 MPa,而采用最高含Mg量的钎料(Al-20Cu-6Si-5Mg)钎焊镀镍后SiC_p/Al复合材料获得的接头剪切强度达到了75.2 MPa。在300°C时,采用Sn-3.5Ag-0.5Cu钎料不能连接SiC_p/Al复合材料,而对镀镍后SiC_p/Al复合材料能够获得良好的钎焊接头,接头的剪切强度达到了45.6 MPa。更多还原

【Abstract】 Silicon carbide(SiC) particle reinforced aluminum matrix composites(SiC_p/Al) with high volume fraction(HFC, ≥50%) have a very broad application prospect in the field of electronic packaging, which are likely to replace the current kovar alloy to become a new generation of electronic packaging materials. However, it is quite difficult to join the HFC SiC_p/Al composites due to the great differences in physical and mechanical properties between the reinforcement and the matrix. Althrough several techniques involving melting welding, diffusion bonding, transient liquid phase bonding and brazing can realize the joining of the HFC SiC_p/Al composites, no one process can be skillfully used in the joining. Among which, brazing has a lot of potentials in the joining of HFC SiC_p/Al composite due to the relatively low brazing temperature, small welding deformation and low residual stress. In this dissertation, the Al-20Cu-6Si-x Mg(x=0、1、3、5, in wt.%) brazing filler metals with different norminal concentrations of Mg element were fabricated, and then the microstmctures, melting characteristic, phase composition, corrosion resistance and tensile strength of the four brazing filler metals were analyzed and discussed. Moreover, the wetting and brazing of 70 vol.%SiC_p/Al composite were investigated using the as-prepared Al-20Cu-6Si-x Mg and commercial Sn-3.5Ag-0.5Cu brazing filler metals.The experimental results showed that the Mg could react with Al to form low melting-point eutectic, which can lower the melting point of the Al-Cu-Si filler metal. The solidus and liquidus temperatures of Al-20Cu-6Si-x Mg(x=0、1、3、5) filler metals are 516.8 oC, 506.8 oC, 504.8 oC, 503.9 oC, and 534.3 oC, 531.9 oC, 529.8 oC, 531.4 oC, respectively. The Al-20 C u-6Si brazing filler metal mainly consisted of α(Al), Al2 C u and Al2 Si phases, and the Al-Cu-Si-Mg brazing filler metals were mainly composed of α(Al), Al2 C u, Al2 Si and Mg2 Si phases. Due to the good solid solution strengthening effect of Mg2 Si, the tensile strength of the Al-Cu-Si-Mg brazing filler metals was enhanced significantly and reached the maximum of 308.6 MPa after solid solution treatment. Moreover, the corrosion resistance of the sample decreased with increasing the Mg concentration due to thin oxidation film since the dissolution rate of Mg2 Si was faster than the formation of oxidation film.The wettability test showed that Mg can improve the wettability of the Al-Cu-Si brazing filler metal on the SiC_p/Al composite by removing the oxidation film on the surfaces of filler metals and base metal. The contact angles of the three Al-Cu-Si-Mg filler metals with 1%、3% and 5% Mg on the SiC_p/Al composites is 143.7°, 132.6°and 125.5°o, respectively. However, the Sn-3.5Ag-0.5Cu filler metal cannot wet the SiC_p/Al composite before N i electroless plating, but can well wet the N i-plated SiC_p/Al composite. The contact angle of Sn-3.5Ag-0.5Cu on the Ni-plated SiC_p/Al composite arrived at 19.4 o at 400 oC for holding 30 min.While brazing the SiC_p/Al composite using the Al-20Cu-6Si-x Mg brazing filler metals at 580 oC, the shear strength of SiC_p/Al composites brazed joints were 25.3, 33.6, 36.3 and 40.7 MPa, respectively; however, the shear strength of the N i-plated SiC_p/Al composite brazed joint using the Al-20 C u-6Si-5Mg brazing filler metal reached 75.2 MPa. The Sn-3.5Ag-0.5Cu filler metal almost can not directly braze the SiC_p/Al composites at 400 °C, but a good joint with the shear strength of 45.6 MPa can be obtained after the N i electroless plating.更多还原