低温下锡基钎料合金冷脆断裂及机理研究

发布时间：2018-06-26 21:22

  本文选题：锡基钎料 + 韧-脆转变　； 参考：《哈尔滨工业大学》2017年硕士论文

【摘要】：在空间探索与航天应用中,航天器中的一些电子器件和设备不得不面临舱外环境,如极低温、大温差等。电子电路的焊点是对热、力环境最为敏感的部位;焊点在极限环境下力学性能发生极大的改变、遭受损伤,导致失效。因此研究电子元器件互连材料在极低温环境下的力学性能及失效模式便十分重要。目前,最常用的电子互连的连接材料为锡基钎料,且研究表明锡基钎料在低温下会发生断裂模式由韧性断裂向脆性断裂的转变,另外Ag元素的加入会对失效温度及模式产生较大影响。因此本课题旨在研究锡基钎料的低温脆断机理。选择纯锡及99.3Sn0.7Cu、96.5Sn3Ag0.5Cu、62Sn36Pb2Ag、63Sn37Pb、10Sn90Pb等5种锡基钎料作为研究对象,在150J的冲击能量、5.24m/s的冲击速度下,在20~-150℃的温度区间内进行了夏比冲击实验。完成冲击实验后通过观察各种钎料的冲击曲线及宏观断口上韧性-脆性断裂区域的比例,得到所研究各种钎料的韧-脆转变温度。在扫描电子显微镜(SEM)下观察不同钎料不同温度下的断口微观组织,使用能谱仪分析所观察到的第二相的成分,最后得出纯锡及锡基钎料不同温度下的断裂机理。研究表明,纯锡的韧脆转变温度在-50℃左右。在20~-40℃内断口为大面积的纤维区;从-50℃开始,出现了冰糖状沿晶断裂的断口形貌,并在局部有穿晶解理断裂的形貌。在锡基钎料中,Cu元素的加入使得99.3Sn0.7Cu钎料的断裂韧性略有上升,但韧-脆转变温度基本不变;与基体生成了纤维状第二相Cu6Sn5,促使断裂模式为穿晶解理断裂。加入Ag元素后,96.5Sn3Ag0.5Cu钎料的韧脆转变温度升高至-40℃,且观察到了枝状及纤维状的Ag3Sn第二相,断裂模式为解理断裂。由于Pb元素的加入,62Sn36Pb2Ag钎料的韧脆转变温度区间很宽,韧脆转变的发生也较为平缓,韧-脆转变温度为-50℃,断裂模式为准解理断裂,在小平面的撕裂棱附近观察到了Ag3Sn颗粒,其作为裂纹源促进了断裂的发生。63Sn37Pb钎料基本没有发生韧脆转变,断口形貌主要以韧窝为主,局部观察到了脆性断裂形貌。当Pb元素含量上升至一定程度,10Sn90Pb钎料一直为韧性断裂,其中含有富锡相作为第二相质点促进微孔集聚型断裂的发生。
[Abstract]:In space exploration and space applications, some electronic devices and equipments in spacecraft have to face the extravehicular environment, such as very low temperature, large temperature difference and so on. The solder joint of electronic circuit is the most sensitive to the thermal and force environment, and the mechanical properties of the solder joint change greatly under the limit environment, which results in the failure of the solder joint. Therefore, it is very important to study the mechanical properties and failure modes of electronic component interconnection materials at very low temperature. At present, the most commonly used bonding material for electronic interconnection is tin solder, and it is shown that the fracture mode of tin based solder will change from ductile fracture to brittle fracture at low temperature. In addition, the addition of Ag element will have a great effect on the failure temperature and mode. Therefore, the purpose of this paper is to study the brittle fracture mechanism of tin-based solders at low temperature. Five kinds of tin based solders, such as pure tin and 99.3Sn0.7CuO96.5Sn3Ag0.5CuCU 62Sn36Pb2Agn63Sn37Pbt10Sn90Pb, were selected as the objects of study. Charpy impact tests were carried out at the temperature range of 20 鈩，

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