本文關(guān)鍵詞： 無鉛焊料 低銀SAC 球柵陣列 金屬間化合物 熱可靠性　出處：《重慶理工大學》2016年碩士論文　論文類型：學位論文

【摘要】：隨著便攜式電子產(chǎn)品的普及,焊點尺寸逐漸減小。同時由于含Pb焊料被限制使用,無鉛焊點中高Sn含量和高互連溫度引起界面金屬間化合物的生長,主導著電子產(chǎn)品封裝的可靠性。在無鉛焊料中,低銀SAC無鉛焊料具有韌性好、抗跌落和抗熱沖擊性好、原材料成本低等優(yōu)點,受到國內(nèi)外學者的關(guān)注,因此其可靠性的系統(tǒng)研究對低銀無鉛焊料的研制及其應用具有重要的科學意義。本文通過添加微量元素來改善低銀Sn-0.45Ag-0.68Cu無鉛焊料的性能,研究了低銀Sn-0.45Ag-0.68Cu/Cu焊點在熱循環(huán)、冷熱沖擊和熱時效下界面IMC的生長演變規(guī)律,綜合分析焊點可靠性和失效模式,結(jié)果表明:(1)低銀SAC/CuBGA焊點在熱沖擊和熱循環(huán)后,界面(Cu,Ni)_6Sn_5 IMC層不斷增厚,其形貌由細長扇貝狀逐漸變得平滑,且疏松的IMC組織變得更加致密;同時,焊點的剪切強度和拉伸強度均呈不斷下降的趨勢,剪切和拉伸斷口都為韌性斷裂模式。與SAC305/Cu焊點相比,低銀Sn-0.45Ag-0.68Cu/Cu焊點在熱沖擊條件下具有與其相媲美的可靠性。(2)熱時效后低銀SAC/CuBGA焊點界面(Cu,Ni)_6Sn_5 IMC層不斷增厚,其形貌逐漸由波浪狀向鋸齒狀轉(zhuǎn)變,并趨于平滑。在100℃、125℃和150℃下時效后BGA焊點界面IMC層的生長系數(shù)分別為5.88×10-19m~2/s、10.68×10-19m~2/s和39.34×10-19m~2/s,其生長激活能為49.41kJ/mol。隨著時效時間的增加,剪切強度和拉伸強度整體呈下降趨勢,且在高溫下焊點的力學性能下降的較快。(3)綜合分析三種熱可靠性,熱沖擊對低銀SAC/Cu焊點剪切強度、抗拉強度以及界面(Cu,Ni)_6Sn_5 IMC層生長速率的影響最大,其后依次為熱循環(huán)和熱時效。對比分析了Co-P鍍層焊盤與Cu焊盤對BGA焊點界面IMC生長的影響,評價了在100℃和150℃熱時效后低銀Sn-0.45Ag-0.68Cu/Co-P BGA焊點的可靠性,并綜合分析了焊點的失效模式,結(jié)果表明,250℃下Co-15%P鍍層對低銀Sn-0.45Ag-0.68Cu焊料具有良好的潤濕性能。熱時效后低銀SAC/Co-P BGA焊點界面CoSn_3 IMC層的厚度總體呈增加的趨勢,且焊料內(nèi)(Cu,Co,Ni)6Sn5 IMC不斷向界面聚集長大引起焊點組織粗化。長時間時效后剪切和拉伸斷口的失效模式均為韌性+脆性混合模式,與低銀SAC/Cu焊點相比,低銀SAC/Co-P焊點在長期使用可靠性方面仍具有較大的優(yōu)勢。
[Abstract]:With the popularization of portable electronic products, the size of solder joint decreases gradually. At the same time, the high Sn content and high interconnect temperature in lead-free solder lead to the growth of intermetallic compounds in the interface due to the limited use of lead-containing solders. In the lead-free solder, low silver SAC lead-free solder has the advantages of good toughness, good drop resistance and thermal impact resistance, low cost of raw materials and so on, which has attracted the attention of scholars at home and abroad. Therefore, the systematic study of its reliability is of great scientific significance for the development and application of low silver lead-free solders. In this paper, the properties of low silver Sn-0.45Ag-0.68Cu lead-free solders are improved by adding trace elements, and the thermal cycling of low silver Sn-0.45Ag-0.68Cu solder joints is studied. The growth and evolution law of interface IMC under cold and thermal shock and thermal aging, and the reliability and failure mode of solder joint are analyzed. The results show that the interface of low silver SAC/CuBGA solder joint increases continuously after thermal shock and thermal cycling. The morphology of the alloy gradually became smooth from the thin scallop shape, and the loose IMC microstructure became denser, and the shear and tensile strength of the solder joint decreased continuously. The shear and tensile fracture are ductile fracture modes. Compared with SAC305/Cu solder joints, low silver Sn-0.45Ag-0.68Cu/Cu solder joints have comparable reliability under thermal shock. After aging at 100 鈩，

本文編號：1514581