一种SACBN07焊膏的制备及焊点抗冷热循环性能

发布时间：2018-08-31 20:13

【摘要】：无铅焊膏是表面贴装技术(SMT)中的重要耗材,随着表面贴装技术的快速发展,无铅焊膏的可靠性研究得到了广泛关注。无铅焊膏的可靠性是与钎料的成分、焊膏的粘度、印刷效果和回流焊温度曲线有关。因此,本文针对新型无铅钎料SACBN07制备性能相匹配的焊膏,在印刷中控制好印刷参数并制定新焊膏的回流曲线进行回流焊接;用所制备的新型焊膏与市场上的SAC305焊膏进行冷热循环实验对比。利用剪切实验、纳米压痕实验等微观测试方法研究冷热循环后界面组织及力学性能的变化。具体内容及结果如下:研究表明:通过三组试验对比得出实验锡膏中新型钎料粉末所占质量分数为87.5%时,焊锡膏的粘度合适印刷效果最好。根据SACBN07钎料的DSC曲线,制定适应的回流工艺曲线更好的发挥焊膏的作用,得到可靠的焊点。回流焊曲线为预热区温度150℃,活性区温度为195℃,保温区温度为260℃,冷却区温度为150℃,整个焊接时间为554 s。对SAC305焊膏和SACBN07焊膏进行铺展实验。SACBN07的铺展系数为84.3%,SAC305锡膏铺展系数为81.1%。新型锡膏的铺展系数略高于SAC305锡膏;Bi、Ni元素的添加增大了SAC系钎料的铺展面积,使焊锡膏润湿性得到改善。在冷热循环600 h实验后,通过统计SAC305和SACBN07两种焊膏所焊接接头出现裂纹的情况,SACBN07/Cu有裂纹焊点的比例29.2%,SAC305/Cu有裂纹焊点的比例为48.3%。冷热循环实验后,SACBN07焊膏与SAC305焊膏形成的焊点的界面化合物逐渐变厚,呈层状生长。600 h后SAC305/Cu焊点界面化合物层明显比SACBN07/Cu焊点界面IMC厚,新型锡膏中的Bi、Ni元素有效的抑制了IMC的生长,SACBN07/Cu界面IMC为蠕虫状的(Cu,Ni)6Sn5,相比高银焊膏SAC305/Cu焊点化合物Cu6Sn5晶粒尺寸明显细化。SACBN07/Cu焊点界面化合物层厚度比SAC305/Cu低16%,SACBN07/Cu界面化合物生长速率更小。Ni的添加对IMC层的生长有很好的抑制作用;Bi的添加使IMC层生长速率下降,低于SAC305/Cu界面IMC的生长速率。600 h冷热循环后SACBN07/Cu体钎料硬度与实验前的相比降低了17.4%,SAC305/Cu与实验前钎料硬度相比降低了31.3%,SACBN07/Cu的软化程度小于SAC305/Cu。冷热循环后SAC305/Cu剪切强度较SACBN07/Cu低31.4%,SACBN07/Cu抗剪切性能优于SAC305/Cu。
[Abstract]:Lead-free solder paste is an important consumable material in surface mounting technology (SMT). With the rapid development of surface mounting technology, the reliability of lead-free solder paste has been widely concerned. The reliability of lead-free solder paste is related to the composition of solder, viscosity of solder paste, printing effect and reflow soldering temperature curve. The solder paste with matching properties was prepared, and the printing parameters were well controlled and the reflux curve of the new solder paste was drawn up for reflux welding. The specific contents and results are as follows: The results show that the best printing effect can be obtained when the mass fraction of the new solder powder is 87.5%. According to the DSC curve of SACBN07 solder, the suitable reflux process curve can be drawn up to better play the role of solder paste. Reliable solder joints. The reflow soldering curve is 150 C in preheating zone, 195 C in active zone, 260 C in insulation zone, 150 C in cooling zone and 554 s in whole soldering time. Experiments on spreading of SAC305 solder paste and SACBN07 solder paste are carried out. The spreading coefficient of SACBN07 is 84.3%, and that of SAC305 solder paste is 81.1%. It is slightly higher than SAC305 solder paste; Bi and Ni increase the spreading area of SAC solder and improve the wettability of solder paste. The interfacial compound of SACBN07 solder paste and SAC305 solder paste became thicker and grew layer by layer after cold and hot cycling test. After 600 hours, the interfacial compound layer of SAC305/Cu solder joint was obviously thicker than that of SACBN07/Cu solder joint. Bi and Ni in the new solder paste inhibited the growth of IMC effectively. The interfacial IMC of SACBN07/Cu was wormlike (Cu, Ni) 6Sn5. Compared with high silver paste SAC305/Cu solder joint compound Cu6Sn5 grain size was significantly refined. SACBN07/Cu solder joint interface compound layer thickness was 16% lower than SAC305/Cu, SACBN07/Cu interface compound growth rate was smaller. Ni addition had a good inhibitory effect on the growth of IMC layer; Bi addition reduced the growth rate of IMC layer, lower than SAC305/Cu interface IMC. The hardness of SACBN07/Cu solder decreases by 17.4%, the hardness of SAC305/Cu decreases by 31.3% and the softening degree of SACBN07/Cu is less than that of SAC305/Cu. The shear strength of SAC305/Cu is 31.4% lower than that of SACBN07/Cu after cold and hot cycling, and the shear resistance of SACBN07/Cu is better than that of SAC305/Cu.
【学位授予单位】：哈尔滨理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG42

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