【作者】 王建华；

【导师】 孟工戈；

【作者基本信息】 哈尔滨理工大学 ， 材料加工工程， 2014， 硕士

【摘要】 随着电子封装技术及封装材料的发展，Sn-Ag-Cu系合金因其较低的熔点及较高的可靠性能等特点，目前已被公认为传统钎料的最佳替代品并取得了实际应用。为了满足电子产品微型化的需求，电子封装中用于连接芯片和基板的焊球尺寸也不断缩小。因此，在长期服役过程中，由于焊点尺寸变小及焊点老化而引起的元器件可靠性问题成为该领域研究人员关注的焦点。本论文研究焊点尺寸、等温时效及镍镀层对SAC305/Cu微焊点界面间化合物演变及镍镀层消耗速率的影响。实验选用Sn-3.0Ag-0.5Cu钎料球，直径分别为200μm、300μm、400μm、500μm，分别在铜盘和镀镍铜盘上进行焊接，然后在100℃、130℃、160℃下分别时效0h、72h、144h、216h、360h后进行分析。研究结果表明：SAC305/Cu焊点界面IMC呈现较明显的尺寸效应，小尺寸焊点界面凹凸不平，化合物形貌为椭球形，晶粒尺寸较大且比较稀疏；随着焊点尺寸的增加，化合物晶粒尺寸明显变小，界面IMC层变的平整均匀。焊点尺寸越大，界面IMC层厚度越薄；界面IMC的生长速率也越小。时效温度对SAC305/Cu微焊点界面IMC影响的研究结果表明，随着时效温度的升高，界面IMC层厚度及生长速率均不断增大。时效时间越长，界面化合物层厚度越大，在回流焊后至时效72h，界面IMC层厚度增长的最快，界面IMC生长速率先是急剧增大，之后逐渐趋于平缓。在三个时效温度下，从回流焊后至时效216h，焊点界面IMC为Cu6Sn5化合物，当时效时间超过360h时，界面处有少量的Cu3Sn化合物生成。镍镀层对SAC305/Cu焊点界面IMC影响显著。钎料与镀镍铜盘反应生成的界面IMC的类型主要为(Cu, Ni)6Sn5化合物，时效一段时间以后，有一层较薄的(Cu, Ni)3Sn和少量的Ag3Sn化合物生成。界面IMC形貌由原来的致密平整变的凹凸不平，成锯齿状。镍镀层对焊点界面IMC生长有明显的抑制作用，即降低界面IMC生长速率，使IMC层厚度变薄。不论焊点大小，回流焊及时效后，焊盘镍镀层剩余厚度均减薄。对于焊点尺寸的影响而言，回流焊后，焊点尺寸越大，剩余镍镀层厚度越薄；时效后，焊点尺寸越大，剩余镍镀层厚度越厚。更多还原

【Abstract】 With the development of electronic packaging technologies and materials,Sn-Ag-Cu alloys have been recognized as the best alternative to traditional solderand have made real application because of the low melting point and highreliability features. In order to meet the demand for miniaturization of electronicproducts, the difference sizes of solder ball which are used for connecting thechip and the substrate in electronic package is shrinking too. Therefore, in thecourse of long-term service, the reliability problem of components which arecaused by the aging and reduction in size is becoming the focus of theresearchers in the field.In this paper, the main research is the effects of isothermal aging, spot sizeand nickel coating to the compound evolution and nickel plating consumptionrate of SAC305/Cu joint. The Sn-3.0Ag-0.5Cu solder balls are used in theexperiment, which the diameters are200μm,300μm,400μm,500μm, thensoldering to the copper plate and nickel-plated copper plate respectively, andanalyze them after aging0h,72h,144h,216h,360h at100℃,130℃,160℃respectively.The results showed that the interfacial IMC of SAC305/Cu joint indicatesize effect obviously. The interface of small joint are irregularities, themorphology of compound is ellipsoidal, the grain size is large and sparse, withthe increases of solder size, the grain size of compound become smallersignificantly, the interfacial IMC layer becomes smooth and uniform. The largerthe spot size, the thinner the thickness of IMC layer, and growth rate of IMC isalso smaller.The study of the effect of aging temperature on SAC305/Cu micro jointsshowed that the thickness of interfacial IMC layer and the growth rates increasewith the of aging temperature increasing. With the aging time prolonging, the thickness of IMC is increasing, in the starting72h, IMC layer is growing fastest,the IMC growth rate increases rapidly and then level off. Under the three agingtemperature, from reflow to216h, the type of solder IMC is mainly the Cu6Sn5compound, after aging360h, a small amount of Cu3Sn generated.The nickel plating has a significant impact on the interfacial IMC ofSAC305/Cu joint. The main types of IMC produced by the reaction of nickelsolder and copper plates is (Cu, Ni)6Sn5compound, after aging for some time,there are a thin (Cu, Ni)3Sn compound layer and a small amount of Ag3Sngenerates. The IMC morphology changed from the original formation of dense touneven, like jagged. Nickel plating inhibited the growth of IMC significantly,which reduce the interfacial IMC growth rate, make the IMC layer thinner.Regardless of the solder size, after reflow and aging, the remaining thickness ofnickel layer is thinning. For the impact of spot size, after reflow, the larger thesolder joint size, the thinner the remaining thickness of nickel coating; afteraging, the remaining thickness of nickel coating is thicker.更多还原