本文選題：SAC + 有限元��； 參考：《哈爾濱理工大學(xué)》2015年碩士論文

【摘要】：焊點(diǎn)的可靠性對封裝器件的壽命至關(guān)重要�！�70%以上的電子器件失效是由焊點(diǎn)失效引起的[1]”焊點(diǎn)作為封裝器件中重要的組成部位，焊點(diǎn)的可靠性決定了封裝器件功能的實(shí)現(xiàn)。 隨著無鉛化研究的不斷深入和SMT（表面貼裝技術(shù)，Surface MountedTechnology）的不斷發(fā)展，新型無鉛釬料要求在綜合性能上（如力學(xué)行為、焊接性及焊點(diǎn)可靠性等）與63Sn37Pb共晶釬料能媲美，甚至超越63Sn37Pb以應(yīng)對在各種惡劣環(huán)境中服役的電子封裝產(chǎn)品對長期穩(wěn)定運(yùn)行的可靠性的要求。其中對焊點(diǎn)力學(xué)行為分析及研究尤為重要。目前BGA焊點(diǎn)在不同加載方式下的可靠性的研究主要是針對溫度循環(huán)、振動沖擊，如熱循環(huán)試驗(yàn)、跌落試驗(yàn)、振動試驗(yàn)等，而對無鉛BGA單個焊點(diǎn)本身的循環(huán)、分級、循環(huán)分級行為研究還少見報道。本文將采用統(tǒng)一的冪指數(shù)蠕變本構(gòu)方程描述焊點(diǎn)的應(yīng)力應(yīng)變行為對BGA焊點(diǎn)在承受循環(huán)、分級、循環(huán)分級載荷的機(jī)械外載過程進(jìn)行有限元模擬，預(yù)測焊點(diǎn)失效的位置，分析應(yīng)力應(yīng)變規(guī)律，并討論了不同加載對BGA焊點(diǎn)力學(xué)行為的影響，本研究對微電子封裝BGA焊點(diǎn)可靠性評價提供一定理論依據(jù)。 本文對Sn-3.0Ag-0.5Cu BGA焊點(diǎn)不同加載方式下的加載過程進(jìn)行數(shù)值模擬。研究不同加載方式對BGA焊點(diǎn)力學(xué)行為的影響。研究結(jié)果表明：在不同加載方式下焊點(diǎn)的易失效位置是相同的，應(yīng)力集中區(qū)域?yàn)槭芰σ粋?cè)下IMC處；塑性應(yīng)變最大的區(qū)域位于不受力一側(cè)上球頸處；單個互連BGA焊點(diǎn)在承受循環(huán)載荷時受力一側(cè)下IMC處殘余應(yīng)力最大，該處最容易導(dǎo)致裂紋擴(kuò)展失穩(wěn)；焊點(diǎn)在承受循環(huán)分級載荷時，不受力一側(cè)上球頸處產(chǎn)生的塑性變形最大，該處最易因局部塑性應(yīng)變集中產(chǎn)生疲勞裂紋。 對焊點(diǎn)分級力學(xué)行為的研究表明：隨著峰值載荷的增加，塑性應(yīng)變成為焊點(diǎn)失效的主要因素；隨著加載速率的增加，等效塑性應(yīng)變區(qū)域由中心向兩側(cè)頸部驟減，應(yīng)力分布規(guī)律基本不變，應(yīng)力的累積成為焊點(diǎn)失效的主導(dǎo)因素；隨著載荷步數(shù)的增加，焊點(diǎn)由于塑性應(yīng)變集中產(chǎn)生裂紋的可能性增加。 對焊點(diǎn)循環(huán)行為的研究表明：隨著峰值載荷的增大，等效塑性應(yīng)變量成為焊點(diǎn)失效的主要原因，同時焊點(diǎn)的疲勞壽命減��；保載時間的增加，只能 使蠕變過程可以進(jìn)行的更充分，但并不能產(chǎn)生額外的蠕變。達(dá)到臨界狀態(tài)后，焊點(diǎn)的疲勞壽命幾乎不受保載時間長短的影響；隨著循環(huán)次數(shù)的增加，焊點(diǎn)的可以充分的發(fā)生塑性變形，而不殘留，，焊點(diǎn)的損傷累計增加，循環(huán)次數(shù)的多少對焊點(diǎn)疲勞壽命的影響越來越小。
[Abstract]:The reliability of solder joint is very important to the life of packaging device. "more than 70% of electronic device failure is caused by the failure of solder joint [1]" as an important part of packaging device. The reliability of solder joint determines the realization of packaging device function. With the development of lead-free research and the development of SMT (Surface Mount Technology), the new lead-free solder is required to match the 63Sn37Pb eutectic solder in its comprehensive properties (such as mechanical behavior, weldability and solder joint reliability). It is even beyond 63Sn37Pb to cope with the reliability requirements of long-term and stable operation of electronic packaging products serving in various harsh environments. It is very important to analyze and study the mechanical behavior of solder joint. At present, the reliability of BGA solder joints under different loading modes is mainly focused on temperature cycle, vibration shock, such as thermal cycle test, drop test, vibration test, etc. Cyclic grading behavior is rarely reported. In this paper, a unified exponential creep constitutive equation is used to describe the stress-strain behavior of solder joints. The mechanical external loading process of BGA solder joints under cyclic, graded and cyclic loading is simulated by finite element method, and the failure position of solder joints is predicted. The effect of different loading on the mechanical behavior of BGA solder joint is analyzed. The research provides a theoretical basis for the reliability evaluation of BGA solder joint in microelectronic packaging. In this paper, the loading process of Sn-3.0Ag-0.5Cu BGA solder joints under different loading modes is numerically simulated. The effect of different loading modes on the mechanical behavior of BGA solder joint was studied. The results show that the failure position of solder joints is the same under different loading modes, the stress concentration region is the IMC under the stress side, the region with the largest plastic strain is located at the ball neck on the unloaded side. The residual stress of single interconnect BGA solder joint under cyclic loading on one side of IMC is the largest, which is the most likely to lead to the instability of crack propagation, and the plastic deformation of the upper ball neck on the side without loading is the largest when the solder joint is subjected to cyclic graded load. Fatigue cracks are most likely to occur due to local plastic strain concentration. The study on the mechanical behavior of solder joints shows that with the increase of peak load, plastic strain becomes the main factor of the failure of solder joints, and with the increase of loading rate, the equivalent plastic strain region decreases sharply from the center to the neck of both sides. The stress distribution law is basically unchanged, and the accumulation of stress becomes the dominant factor for the failure of solder joints, and with the increase of load steps, the possibility of cracking in solder joints due to the concentration of plastic strain increases. The study on the cyclic behavior of solder joint shows that with the increase of peak load, the equivalent plastic strain becomes the main reason for the failure of the solder joint, and the fatigue life of the solder joint decreases, and the increase of the loading time can only lead to the increase of the fatigue life of the solder joint. The creep process can be carried out more fully, but no additional creep can be generated. After reaching the critical state, the fatigue life of the solder joint is almost unaffected by the length of the holding time, and with the increase of cycle times, the joint can be fully plastic deformed, but without residual, the damage of the solder joint accumulates, and the fatigue life of the solder joint increases with the increase of cycle times. The effect of the number of cycles on the fatigue life of solder joint is smaller and smaller.
【學(xué)位授予單位】：哈爾濱理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TN05

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