【作者】 周浩浩；

【导师】 孔见；

【作者基本信息】 南京理工大学 ， 材料学， 2010， 硕士

【摘要】 本文从助焊剂的选材着手,通过正交试验法选出助焊剂的最佳组分,并对助焊剂进行性能测试。然后将该助焊剂与Sn-Ag-Cu合金焊粉配置成无铅焊膏,按照标准对制备的焊膏与市售的焊膏进行性能对比。主要研究结果如下：助焊剂的主要成分包括松香、活性剂、成膜剂和溶剂。其中松香的选取是将精制氢化松香与水白松香以1：1进行复配；活性剂选择将柠檬酸与硬脂酸以2：1进行复配,并加入三乙醇胺作为辅助活性剂和酸度调节剂；成膜剂选定为聚乙二醇2000；免清洗助焊剂和松香型助焊剂中溶剂均为乙醇、丙三醇、二乙二醇丁醚,只是比例不同,前者为3：5：2,后者为3：4：3。研究表明：免清洗型助焊剂中对铺展面积指标影响顺序为活性剂>温度>松香>溶剂；松香型助焊剂对铺展面积指标影响顺序为温度>松香>溶剂>活性剂。根据标准对助焊剂进行检测：免清洗型助焊剂外观为乳白半透明液体,PH值为5.1,不挥发物含量为17.57%；松香型助焊剂为淡黄色透明液体,PH值为5.4,不挥发物含量为26.56%。两种助焊剂经稳定性测试后,均无明显的分层或结晶物析出现,可以满足使用要求。将优化后的助焊剂与Sn-Ag-Cu合金焊料混合制备焊膏,免清洗型焊膏中焊粉与助焊剂比值为8.8：1.2,而松香型焊膏为9：1。根据标准将制备焊膏与市售焊膏进行性能检测：焊料球测试中免清洗型焊膏、松香型焊膏和市售焊膏在放置时间为15±5mmin均为1级；放置时间为4h±15min时,松香型焊膏和市售焊膏等级为1级。免清洗焊膏铺展面积为36.72mm2,扩展率为84.52%；松香型焊膏铺展面积为39.84 mm2,扩展率为87.35%；市售焊膏为35.94 mm2,扩展率为85.48%。制备焊膏经回流焊接后,界面组织良好,均有明显的IMC层出现,免清洗型焊膏的IMC层为1～3μm,松香型焊膏的IMC层为3-5μm,均优于市售焊膏的IMC层(4～6μm)。更多还原

【Abstract】 This work started from choosing the optimum component of fluxes through orthogonal experiment and some performance tests of the fluxes were proceeded accordingly. Then the chosen fluxes were mixed with Sn-Ag-Cu alloy solder to synthesize lead-free solder pastes. The following results are obtained from comparing the performances of resultant solder pastes with the purchased solder paste according to the standard.The major results are as follows:The main components of flux are rosin、activator、filmogen and solvent. In this work, the rosin was prepared by mixing refined hydrogenated rosin and water-white rosin with the ratio of 1:1;the activator was prepared by mixing citric acid and stearic acid with the ratio of 2:1; meanwhile, triethanolamine was added as a secondary activator and acidity regulator; the filmogen was decided to be polyethylene glycol 2000;the solvent of no-clean flux and rosin-based flux were both composed by ethanol、glycerol and diethylene glycol monobutyl ether while they differed in proportion(the former is 3:5:2,the latter is 3:4:3).The results indicate that the degree of influence on spreading areas varies with different components.In no-clean flux, the order is activator>temperature> rosin> solvent while in rosin-based flux it is temperature>rosin>solvent>activator. Examination of the two fluxes was carried out according to the standard:no-clean flux is milky white translucent liquid with PH value of 5.1 and 17.57% non-volatile matter. Rosin-based flux is light yellow transparent liquid with PH value of 5.4 and 26.56% non-volatile matter. The stability test of the two fluxes shows there isn’t obvious appearance of delamination or crystals which means they can meet the request of utilization.The optimized fluxes were mixed with Sn-Ag-Cu alloy solder with different ratios to make different solder pastes. The ratio of flux to alloy solder in no-clean solder paste was 8.8:1.2,and in rosin-based solder paste it was 9:1.Then the performance of the prepared solder paste as well as the purchased solder paste was tested according to the standard. In the solder ball test, all the solder pastes are evaluated as 1 class in 15minutes (with the fluctuation of 5 minutes).After 4 hours (with the fluctuation of 15 minutes), the rosin-based solder paste and the purchased solder paste stays 1 class.The spreading area of no-clean solder paste, rosin-based solder paste and purchased solder paste is 36.72 mm2,39.84 mm2 and 35.94 mm2 respectively;the spread rate is 84.52%,87.35% and 85.48% respectively. After reflow soldering, the three solder pastes all have obvious IMC layer with different thickness:the no-clean solder paste is 1-3μm,the rosin-based flux is 1-5μm.They are both better than the purchased solder paste (4～6μm).更多还原