大温变条件下QFP器件组装焊点可靠性研究
发布时间：2019-03-15 16:43
【摘要】：随着科技水平的不断提高,人类对未知领域探索能力不断加强,深空探测已成为各国竞争的热点。相比于我国已取得相当成就的近地探测领域,严酷的深空环境对航天电子器件可靠性提出了更高的要求和挑战,与NASA针对极低温大温变条件下(-180°C~+150°C)的电子产品可靠性开展了不少于15年系统研究相比,我国在此领域研究尚处于起步阶段,严重影响了我国长寿命深空探测任务的实施,因此急需开展一系列基础研究填补空白。针对以上要求,本实验选用了航天中常用的Sn基Sn63Pb37和SAC305钎料,以及由两种钎料组装的QFP(方形扁平封装)器件作为研究对象,通过0~300周极低温大温变(-196°C~+150°C)热冲击循环后的钎料拉伸试验、引脚力学性能试验和焊点微观组织观察来分析极端环境带来的影响,从钎料到器件系统性的分析两种钎料性能差异和组织演变规律,旨在揭示钎料和焊点在极端环境下的失效机理,全面评估两种钎料的可靠性。研究结果表明:在0.001/s和0.01/s应变速率下,Sn63Pb37钎料拉伸强度比SAC305分别平均高出59.1%和48.0%,且在循环过程中前者具有更好的力学稳定性,其钎料组织也保持均匀稳定。断口SEM分析发现两种钎料断裂方式均以韧性断裂为主,但在高应变速率和高循环周期(Sn63Pb37:100~300周、SAC305:250~300周)下出现脆化倾向,属于混合型断裂。引脚力学性能测试发现,采用两种钎装组装的QFP器件,随着循环进行,其边侧引脚和中间引脚拉伸强度都呈下降趋势,但所有引脚强度均高于失效标准。整体来看,SAC305钎料引脚力学性能略优于Sn63Pb37钎料。引脚断口分析表明随着循环周期增加,两种钎料引脚的断裂方式均由韧性断裂逐渐转变为脆性断裂。引脚焊点剖面分析观察裂纹和空洞情况时发现SAC305钎料抗疲劳性能更加优异。两种钎料焊盘侧IMC形貌由扇贝状逐渐转变为层状,且SAC305钎料的界面化合物更厚,计算出的Sn63Pb37/焊盘界面和SAC305/焊盘界面的金属间化合物生长指数分别为0.3723和0.3357,属于晶界扩散方式。由于SAC305钎料与焊盘和IMC的CTE匹配性较好,因此具有较好抗疲劳性能,同时通过对比钎料上下侧IMC厚度发现ENIG(化学镀镍金)焊盘对IMC生长具有抑制作用。
[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 掳C ~ 150 掳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 掳C ~ 150 掳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.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：V443;TG425
，
本文编号：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 掳C ~ 150 掳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 掳C ~ 150 掳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.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：V443;TG425
，
本文编号：2440803
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