本文選題：可靠性 + 釬料氣泡　； 參考：《大連理工大學》2016年博士論文

【摘要】：隨著電子封裝工業(yè)不斷小型化、無鉛化,焊點的可靠性也引起了廣大研究者的高度重視。在以銅為基體的錫基釬料焊點或?qū)咏宇^結(jié)構(gòu)中,除釬料／基體界面生成脆性IMC的厚度和形狀是影響焊接強度的關(guān)鍵因素外,界面區(qū)的氣泡和微孔洞等缺陷可降低焊點有效連接面積,并會產(chǎn)生應力集中,同樣是導致焊點失效的重要隱患。因此,深入研究界面氣泡生長、演化行為；界面IMC生長行為；氣泡存在對界面IMC生長影響等,不僅可以深入闡明釬焊機理,同時對提高釬焊接頭可靠性有重要的理論指導意義。本文應用同步輻射實時成像技術(shù)及常規(guī)釬焊試驗對界面氣泡進行了深入研究,并對溫度梯度與電勢梯度作用下釬焊過程中界面IMC的生長行為進行了研究,利用以上研究結(jié)果,結(jié)合數(shù)值模擬手段,重點創(chuàng)建了FEM模型、AEH方法和DANPHE軟件,引用FVM模型和Elmer軟件、FiPy軟件對釬焊過程氣泡生長、演化行為及場梯度條件下界面IMC生長行為進行了模擬分析,獲得以下結(jié)果：(1)應用同步輻射實時成像技術(shù)對液態(tài)Sn/Cu界面上初始直徑為20μm的氣泡生長進行在線觀察,以此為基礎(chǔ)創(chuàng)建一種基于有限元法的數(shù)值模型(FEM)引用Elmer軟件對此過程進行模擬分析。同步輻射結(jié)果顯示,動態(tài)生長界面IMCs上的氣泡生長會經(jīng)歷一個由潤濕控制的轉(zhuǎn)變過程：氣泡與IMCs的接觸角會從最初的鈍角不斷減小,向直角(半球氣泡點)、銳角轉(zhuǎn)化,直到氣泡完全變?yōu)閳A形達到動態(tài)平衡；數(shù)值模擬結(jié)果顯示,氣泡與IMCs接觸角越大,氣泡的最終尺寸也越大,相同的釬焊時間內(nèi)平均生長速度就越大；綜合同步輻射和數(shù)值模擬結(jié)果可知,氣泡在早期生長較快,后期生長較慢。(2)研究氣泡對界面IMCs生長影響發(fā)現(xiàn),氣泡的存在阻隔了釬料和銅基體的反應,將界面IMC劃分為不生長、半生長和全生長三類IMCs。不生長IMC是指氣泡正下方,由于受到氣泡的阻礙釬料無法與基板接觸,完全不能生長的IMC；半生長IMC是指臨近氣泡區(qū)域,受到氣泡的影響部分生長的IMC；全生長IMC是指遠離氣泡,不受氣泡影響而完全生長的IMC。因此,根據(jù)半生長和全生長IMC的界限可以預測氣泡的尺寸。(3)在含有氣泡的液固界面上,釬料中氣泡的存在會導致周圍材料物理性能的變化,進而影響釬焊過程。應用以FEM模型為基礎(chǔ)的漸進擴展均勻化AEH方法,模擬計算出含氣泡熔融焊料中垂直界面方向Cu的有效擴散系數(shù)和Sn熱導率等影響釬焊物理參數(shù)的變化,以此評估氣泡存在時釬焊焊點的質(zhì)量。(4)在溫度梯度下IMC生長研究中,創(chuàng)立了一種以MOOSE結(jié)構(gòu)為基礎(chǔ)的DANPHE軟件,應用FEM模型對釬焊過程進行了模擬,模擬結(jié)果與常規(guī)釬焊和同步輻射實時成像技術(shù)測得是實驗數(shù)據(jù)吻合,模型應用準確。結(jié)果顯示：相對250℃,350℃純Sn體系對接焊點冷端IMC厚度較大,說明相同溫度梯度下,釬焊溫度越高,冷端IMC生長速率越快；同時發(fā)現(xiàn),350℃下Sn3.5Ag釬料中冷端IMC生長厚度小于純Sn中IMC厚度,說明Ag3Sn的形成抑制了冷端界面IMC的生長。(5)在電勢梯度試驗條件下,應用已創(chuàng)建的FEM模型/DANPHE軟件或引用FVM(有限元體積法)模型/FiPy軟件進行數(shù)值模擬,同時應用已創(chuàng)建的FEM模型/DANPHE軟件計算焦耳熱。結(jié)果顯示,模擬數(shù)據(jù)與同步輻射實時成像技術(shù)觀察陽極IMC生長行為(試驗條件為250℃間距為450μm和1.234mm的Cu/Sn/Cu對接焊點分別通以0.56×103 A/cm2和3.0×103 A/cm2的電流進行回流)的試驗數(shù)據(jù)非常吻合,模型應用準確；電勢梯度下,陽極IMCs厚度隨釬焊時間呈線性增長,符合線性動力學關(guān)系；電流密度越大,線性斜率越大,陽極IMC生長越快；同時發(fā)現(xiàn)在釬焊過程中焊點的溫度會有變化,低電流密度下液態(tài)釬料的溫度變化較小,3.0×103A/cm2的電流密度下焊點溫度則提高了近40℃,但電遷移驅(qū)動力對IMC生長的作用依然明顯大于擴散梯度的影響；對接焊點間距越大,電場下后期陽極IMC增長越快。
[Abstract]:With the miniaturization and lead-free of the electronic packaging industry, the reliability of the solder joints has been paid great attention by the researchers. In the solder joints or butt joints of copper based solder joints, the thickness and shape of the brittle IMC generated by the solder / substrate interface are the key factors affecting the welding strength, and the bubbles and micropores in the interface zone Holes and other defects can reduce the effective connection area of the solder joints and produce stress concentration, which is also an important hidden danger in the failure of the solder joints. Therefore, the deep study of the growth and evolution behavior of the interface bubbles, the growth behavior of the interface IMC, the effect of the existence of bubbles on the growth of the interface IMC, and so on, can not only clarify the brazing mechanism, but also improve the brazing joint. It has important theoretical guiding significance. In this paper, the interface bubbles are studied by the real-time imaging technology of synchrotron radiation and the conventional brazing test. The growth behavior of the interface IMC in the brazing process under the effect of temperature gradient and potential gradient is studied. FEM model, AEH method and DANPHE software, FVM model and Elmer software, FiPy software are used to simulate the bubble growth, evolution behavior and interfacial IMC growth behavior under the field gradient conditions. The following results are obtained: (1) the growth of bubble growth with initial diameter of 20 mu on the liquid Sn/Cu interface is obtained by using real-time synchrotron radiation imaging technology. A numerical model based on the finite element method (FEM) is built on the basis of the finite element method (FEM) to simulate the process. The synchrotron radiation results show that the bubble growth on the dynamic growth interface will undergo a transition process by the wetting control: the contact angle between the bubble and the IMCs will continue from the original obtuse angle. The results show that the larger the contact angle between the bubbles and IMCs, the larger the bubble size, the greater the average growth rate in the same brazing time, and the results of synchrotron radiation and numerical simulation show that the bubble is in the early stage. Growth is faster and later growth is slow. (2) the study of the effect of bubble on the growth of interface IMCs found that the existence of bubbles obstructed the reaction between the brazing and the copper matrix, divided the interface IMC into non growth, and the semi growth and full growth of the non growth of the IMCs. IMC means that the bubble was under the front of the bubble, and the brazing filler metal could not be exposed to the substrate because of the obstruction of the bubble. Long IMC; half long IMC refers to the IMC that is growing near the bubble region and affected by bubbles; the full growth IMC is a IMC. that is completely grown away from the bubble and is not affected by the bubble. Therefore, the size of the bubble can be predicted according to the boundary of semi growth and full growth of IMC. (3) the existence of bubbles in the liquid and solid interface containing bubbles. The physical properties of the surrounding materials will be changed and the brazing process will be influenced. The incremental and homogenized AEH method based on the FEM model is applied to simulate the effect of the effective diffusion coefficient and the thermal conductivity of the Sn on the physical parameters of the brazing, which can be used to evaluate the brazing solder joint in the presence of the bubble in the molten solder. (4) in the study of IMC growth under the temperature gradient, a kind of DANPHE software based on the MOOSE structure was founded. The brazing process was simulated with the FEM model. The simulation results were consistent with the conventional brazing and synchrotron radiation real-time imaging technology, and the model type application was accurate. The results showed that the pure Sn body was 250 and 350. The IMC thickness at the cold end of the butt joint shows that the higher the brazing temperature, the faster the growth rate of the cold end IMC under the same temperature gradient. At the same time, it is found that the growth thickness of the cold end IMC is less than the IMC thickness in the pure Sn at 350 C, indicating that the formation of Ag3Sn inhibits the growth of IMC at the cold end interface. (5) under the condition of the potential gradient test, the application has been established. The FEM model /DANPHE software or the FVM (finite element volume) model /FiPy software is used to simulate the numerical simulation, and the Joule heat is calculated with the created FEM model /DANPHE software. The results show that the simulation data and synchrotron radiation real-time imaging technique observe the growth behavior of the anode IMC (the test condition is 250 c interval of 450 mu m and 1.234mm Cu/Sn/. " The test data of Cu butt solder joint with 0.56 x 103 A/cm2 and 3 x 103 A/cm2 current respectively coincide with the experimental data, and the application of the model is accurate. Under the potential gradient, the anode IMCs thickness is linearly increased with the brazing time, which is in line with the linear dynamics; the greater the current density, the greater the linear slope, the faster the growth of the anode IMC, and found at the same time. The temperature of solder joints will change in the process of brazing, and the temperature of the liquid solder is smaller under the low current density. The temperature of the solder joint is nearly 40 degrees under the current density of 3 x 103A/cm2, but the effect of the electromigration drive on the growth of IMC is still greater than the effect of the diffusion gradient; the larger the distance between the butt welding points and the growth of the anode IMC in the later stage of the electric field The faster.

【學位授予單位】：大連理工大學
【學位級別】：博士
【學位授予年份】：2016
【分類號】：TG40
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本文編號：1863253