大溫變條件下QFP器件組裝焊點可靠性研究
發(fā)布時間：2019-03-15 16:43
【摘要】：隨著科技水平的不斷提高,人類對未知領(lǐng)域探索能力不斷加強,深空探測已成為各國競爭的熱點。相比于我國已取得相當(dāng)成就的近地探測領(lǐng)域,嚴(yán)酷的深空環(huán)境對航天電子器件可靠性提出了更高的要求和挑戰(zhàn),與NASA針對極低溫大溫變條件下(-180°C~+150°C)的電子產(chǎn)品可靠性開展了不少于15年系統(tǒng)研究相比,我國在此領(lǐng)域研究尚處于起步階段,嚴(yán)重影響了我國長壽命深空探測任務(wù)的實施,因此急需開展一系列基礎(chǔ)研究填補空白。針對以上要求,本實驗選用了航天中常用的Sn基Sn63Pb37和SAC305釬料,以及由兩種釬料組裝的QFP(方形扁平封裝)器件作為研究對象,通過0~300周極低溫大溫變(-196°C~+150°C)熱沖擊循環(huán)后的釬料拉伸試驗、引腳力學(xué)性能試驗和焊點微觀組織觀察來分析極端環(huán)境帶來的影響,從釬料到器件系統(tǒng)性的分析兩種釬料性能差異和組織演變規(guī)律,旨在揭示釬料和焊點在極端環(huán)境下的失效機理,全面評估兩種釬料的可靠性。研究結(jié)果表明:在0.001/s和0.01/s應(yīng)變速率下,Sn63Pb37釬料拉伸強度比SAC305分別平均高出59.1%和48.0%,且在循環(huán)過程中前者具有更好的力學(xué)穩(wěn)定性,其釬料組織也保持均勻穩(wěn)定。斷口SEM分析發(fā)現(xiàn)兩種釬料斷裂方式均以韌性斷裂為主,但在高應(yīng)變速率和高循環(huán)周期(Sn63Pb37:100~300周、SAC305:250~300周)下出現(xiàn)脆化傾向,屬于混合型斷裂。引腳力學(xué)性能測試發(fā)現(xiàn),采用兩種釬裝組裝的QFP器件,隨著循環(huán)進(jìn)行,其邊側(cè)引腳和中間引腳拉伸強度都呈下降趨勢,但所有引腳強度均高于失效標(biāo)準(zhǔn)。整體來看,SAC305釬料引腳力學(xué)性能略優(yōu)于Sn63Pb37釬料。引腳斷口分析表明隨著循環(huán)周期增加,兩種釬料引腳的斷裂方式均由韌性斷裂逐漸轉(zhuǎn)變?yōu)榇嘈詳嗔�。引腳焊點剖面分析觀察裂紋和空洞情況時發(fā)現(xiàn)SAC305釬料抗疲勞性能更加優(yōu)異。兩種釬料焊盤側(cè)IMC形貌由扇貝狀逐漸轉(zhuǎn)變?yōu)閷訝?且SAC305釬料的界面化合物更厚,計算出的Sn63Pb37/焊盤界面和SAC305/焊盤界面的金屬間化合物生長指數(shù)分別為0.3723和0.3357,屬于晶界擴(kuò)散方式。由于SAC305釬料與焊盤和IMC的CTE匹配性較好,因此具有較好抗疲勞性能,同時通過對比釬料上下側(cè)IMC厚度發(fā)現(xiàn)ENIG(化學(xué)鍍鎳金)焊盤對IMC生長具有抑制作用。
[Abstract]:With the development of science and technology, the ability of human to explore unknown fields has been strengthened, and deep space exploration has become a hot point of competition among countries. Compared with the field of near-Earth detection, which has achieved considerable achievements in China, the harsh deep space environment puts forward higher requirements and challenges to the reliability of space electronic devices. Compared with the systematic research on the reliability of electronic products (- 180 擄C ~ 150 擄C) carried out by NASA for no less than 15 years under extremely low temperature and large temperature variation, the research in this field in China is still in the initial stage, which seriously affects the implementation of the long-life deep space exploration mission in China. Therefore, it is urgent to carry out a series of basic research to fill the gap. In order to meet the above requirements, Sn-based Sn63Pb37 and SAC305 solders, which are commonly used in aerospace, and QFP (Square flat package) devices assembled by two kinds of solders are chosen as the research objects in this experiment. The influence of extreme environment was analyzed by tensile test, pin mechanical property test and microstructure observation of soldering joint after 300 cycles of extreme low temperature and high temperature change (- 196 擄C ~ 150 擄C) after thermal shock cycling. In order to reveal the failure mechanism of solder and solder joint in extreme environment and to evaluate the reliability of the two kinds of solder systematically, the differences of properties and microstructure evolution between the two kinds of solder are systematically analyzed from solder to device in order to reveal the failure mechanism of solder and solder joint in extreme environment. The results show that the tensile strength of Sn63Pb37 solder is 59. 1% and 48. 0% higher than that of SAC305 on average at the strain rate of 0. 001 and 0. 01%, respectively, and the former has better mechanical stability in the process of cycling, and the tensile strength of the solder is 59.1% and 48. 0% higher than that of SAC305, respectively. The microstructure of the solder also keeps uniform and stable. Fracture SEM analysis shows that the fracture modes of both brazing metals are mainly ductile fracture, but brittle tendency appears under high strain rate and high cycle period (Sn63Pb37:100~300 cycle, SAC305:250~300 cycle), which belongs to mixed fracture. The mechanical properties of the pins show that the tensile strength of both the side and the middle pins decreases with the cycling of the two kinds of brazed QFP devices, but the strength of all the pins is higher than the failure standard. Overall, the mechanical properties of SAC305 solder pin are slightly better than that of Sn63Pb37 solder. The fracture analysis of the pins shows that the fracture modes of the two solder pins gradually change from ductile fracture to brittle fracture with the increase of cycle period. It is found that the fatigue resistance of SAC305 solder is better when the soldering joint section of the pin is analyzed and observed under the condition of cracks and voids. The morphology of IMC changed from scallop to layer gradually, and the interface compound of SAC305 solder was thicker. The growth index of intermetallic compounds at the interface of Sn63Pb37/ solder pad and SAC305/ solder pad was calculated to be 0.3723 and 0.3357, respectively. It belongs to grain boundary diffusion mode. Because SAC305 solder matches well with CTE of solder pad and IMC, it has better anti-fatigue property. It is found that ENIG (electroless nickel-gold) pad can inhibit the growth of IMC by comparing the thickness of IMC on the upper and lower sides of solder.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2016
【分類號】：V443;TG425
，
本文編號：2440803
[Abstract]:With the development of science and technology, the ability of human to explore unknown fields has been strengthened, and deep space exploration has become a hot point of competition among countries. Compared with the field of near-Earth detection, which has achieved considerable achievements in China, the harsh deep space environment puts forward higher requirements and challenges to the reliability of space electronic devices. Compared with the systematic research on the reliability of electronic products (- 180 擄C ~ 150 擄C) carried out by NASA for no less than 15 years under extremely low temperature and large temperature variation, the research in this field in China is still in the initial stage, which seriously affects the implementation of the long-life deep space exploration mission in China. Therefore, it is urgent to carry out a series of basic research to fill the gap. In order to meet the above requirements, Sn-based Sn63Pb37 and SAC305 solders, which are commonly used in aerospace, and QFP (Square flat package) devices assembled by two kinds of solders are chosen as the research objects in this experiment. The influence of extreme environment was analyzed by tensile test, pin mechanical property test and microstructure observation of soldering joint after 300 cycles of extreme low temperature and high temperature change (- 196 擄C ~ 150 擄C) after thermal shock cycling. In order to reveal the failure mechanism of solder and solder joint in extreme environment and to evaluate the reliability of the two kinds of solder systematically, the differences of properties and microstructure evolution between the two kinds of solder are systematically analyzed from solder to device in order to reveal the failure mechanism of solder and solder joint in extreme environment. The results show that the tensile strength of Sn63Pb37 solder is 59. 1% and 48. 0% higher than that of SAC305 on average at the strain rate of 0. 001 and 0. 01%, respectively, and the former has better mechanical stability in the process of cycling, and the tensile strength of the solder is 59.1% and 48. 0% higher than that of SAC305, respectively. The microstructure of the solder also keeps uniform and stable. Fracture SEM analysis shows that the fracture modes of both brazing metals are mainly ductile fracture, but brittle tendency appears under high strain rate and high cycle period (Sn63Pb37:100~300 cycle, SAC305:250~300 cycle), which belongs to mixed fracture. The mechanical properties of the pins show that the tensile strength of both the side and the middle pins decreases with the cycling of the two kinds of brazed QFP devices, but the strength of all the pins is higher than the failure standard. Overall, the mechanical properties of SAC305 solder pin are slightly better than that of Sn63Pb37 solder. The fracture analysis of the pins shows that the fracture modes of the two solder pins gradually change from ductile fracture to brittle fracture with the increase of cycle period. It is found that the fatigue resistance of SAC305 solder is better when the soldering joint section of the pin is analyzed and observed under the condition of cracks and voids. The morphology of IMC changed from scallop to layer gradually, and the interface compound of SAC305 solder was thicker. The growth index of intermetallic compounds at the interface of Sn63Pb37/ solder pad and SAC305/ solder pad was calculated to be 0.3723 and 0.3357, respectively. It belongs to grain boundary diffusion mode. Because SAC305 solder matches well with CTE of solder pad and IMC, it has better anti-fatigue property. It is found that ENIG (electroless nickel-gold) pad can inhibit the growth of IMC by comparing the thickness of IMC on the upper and lower sides of solder.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2016
【分類號】：V443;TG425
，
本文編號：2440803
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