【作者】 王艳；

【导师】 程方杰；

【作者基本信息】 天津大学 ， 材料加工工程， 2010， 硕士

【摘要】 由于其良好的工艺性能,传统的Sn-Pb钎料合金在微电子组装与封装领域中有着广泛的应用。由于Pb对人类健康和环境的有害影响,近年来各国均立法限制含Pb钎料在微电子制造领域的应用,大力推广无铅钎料及无铅钎焊工艺。而含Pb的质量分数超过85%的高固相线钎料(如Sn-90Pb的固相线温度为268℃)还没有找到合适的替代材料,以RoHS为代表的相关法规对微电子行业中特定用途高铅钎料的使用给予暂时豁免。但在全球范围内电子封装无铅化迅速发展,全面禁止这些含Pb钎料的使用迫在眉睫,尽快研制高固相线的无铅钎料及其他无铅互连工艺势在必行。Zn基钎料合金作为高铅钎料替代品引起了学者的关注。研究发现,在Zn-A1钎料中添加第三组元Mg可有效降低熔点,Zn-4A1-3Mg钎料合金熔化温度为340℃。本文通过在Zn-A1-Mg合金中添加微量元素Sn,制备Zn-Al-Mg-xSn钎料合金,通过研究钎料合金的熔化特性、显微组织形貌、力学性能和铺展性能,希望其对高温电子封装领域的使用具有重要意义。Zn-4Al-3Mg合金主要由MgZn2、Mg2Zn11、β(ZnAl)及η(Zn)组成,低熔点富Sn相呈点状分布于晶界上,使合金熔点略有降低。Zn-Al-Mg钎料合金硬度为HV89.07,随着第四组元Sn的加入,合金硬度明显下降。在不同温度下的拉伸试验结果表明,Zn-Al-Mg钎料合金常温下为脆性断裂,高温下为韧性断裂,断口出现明显的韧窝,塑性较好;添加Sn元素后,均为脆性断裂,导致抗拉强度下降明显。Zn基钎料在Cu基板上的铺展试验表明,在界面上形成笋状化合物并向钎料侧生长;Zn基钎料在Al基板上的铺展试验表明,在合适的助焊剂作用下铺展性能优良,润湿角接近于0°。铺展性试验结果还表明,该钎料对Al基板的溶蚀作用较严重,界面凹凸不平。由于Zn与Al间形成晶间渗透,钎料呈现晶花状,形成冶金连接。钎料合金在制备钎焊接头时,由于快速加热,接头边缘处存在助焊剂残渣及气孔缺陷,影响接头的可靠性。更多还原

【Abstract】 Due to its good process performance, the traditional Sn-Pb solder alloy is widely used in microelectronic assembly and packaging fields. Due to Pb is harmful to the human health and the environment, legislative have been made by various countries to restrict the use of the solder containing Pb in the fields of microelectronics applications in recent years, and promote lead-free solder materials and soldering processes. While a suitable alternative materials have not yet been found to substitute the solder including Pb(mass ratio) higher than 85%, for example, so the laws and regulations represented by RoHS give the exemption of the using about high-lead solder in microelectronics industry temporarily. However, with the rapid development of lead-free electronic manufactures, a complete prohibition on the use of solder containing Pb is imminent, so it is imperative to develop a new lead-free solder and other lead-free interconnect process as quickly as possible.Zn-based solder alloy have several advantages, such as low cost, but the process performance and working performance should be improved. The research indicated, adding the third element Mg in Zn-A1 can effectively reduce the melting point to 340℃. To add the trace element, Sn, and prepare a new type Zn-Al-Mg-xSn solder alloy. The melting properties, microstructure morphology, mechanical properties and spreading performance were studied in the present paper. The results should be important for the use of Zn-based higher solidus solder in the high temperature electrical packaging.Zn-4A1-3Mg solder alloys is mainly composed with MgZn2, Mg2Zn11,β(ZnAl) andη(Zn), and the Sn-rich phase which distributed in the boundary and contribute to the slightly decline of the melting point. The hardness of Zn-4Al-3Mg solder alloy is about HV89. However with the addition of Sn, the hardness decreased significantly. The tensile test results in different temperature revealed that the Zn-Al-Mg solder alloy is brittle fracture at room temperature, while at 200℃it is ductile fracture with apparent dimple, so the plastic performance is good. After adding the element Sn, the fracture is brittle no matter what the temperature is, and the tensile strength decreased significantly too. The spreading experiment on the Cu substrate shows that, in the surface the bamboo-like inter metallic compounds growing to the direction of solder. The spreading experiment on the Al substrate show that, with the help of the suitable flux it can achieve good wetting performance and the wetting angle is close to 0°. It also illustrate that the erosion is noticeable and the interface is uneven. Because of the concentration between Zn and Al, there is crystal flower in the solder forming the metallurgical bonding. As a result of the rapid heating, a small amount of the flux residue in the joints, which have a negative effect on the reliability of the joint.更多还原