【作者】 靳洪允；

【导师】 侯书恩；

【作者基本信息】 中国地质大学 ， 岩石矿物材料学， 2009， 博士

【摘要】 随着微电子工业的迅速发展，作为大规模集成电路封装领域的关键材料——高纯度球形硅微粉的研究越来越受到关注。本研究分别以天然石英和稻壳为原料，结合氧气-乙炔火焰法制备大规模集成电路封装要求的高纯度球形石英粉和超大规模集成电路封装要求的低放射性球形硅微粉。具体工作包括：第一，提出了机械-化学方法相结合的石英提纯新工艺，提纯的同时实现石英超细粉碎和颗粒预整形，制备了具有一定流动性的高纯度石英微粉；第二，利用我国丰富的稻壳为原料，利用碱溶液法制备水玻璃、通过离子交换法交换去除Na⁺、K⁺、Al³⁺、Fe³⁺、Cl^-等离子制备高纯度硅溶胶、对硅溶胶进行喷雾造粒制得类球形氧化硅微粉、焙烧后得到具有一定流动性的焙烧造粒氧化硅微粉；第三，开发新的氧气-乙炔火焰法球形化工艺，研制氧气-乙炔火焰法球形化专用设备：超细微粉送粉器、火焰燃烧器、球形化炉，设计配套微粉冷却和收集装置；第四，分别以上述制备的高纯度石英微粉和类球形的造粒氧化硅微粉为原料对其进行球形化处理，制备了两种球形硅微粉；最后，将制备的球形硅微粉分别与E-51型环氧树脂复合，对SiO₂／E-51环氧塑封料的热膨胀性能、热稳定性能及力学性能进行了研究。取得如下几个方面的进展：1、开发了球磨结合复配酸的机械-化学石英提纯新工艺。通过对脉石英原料的矿物组成、矿物的赋存状态、化学成分等进行研究，在传统复配酸提纯石英的基础上，开发了球磨结合复配酸的机械-化学石英提纯新工艺。对比复配酸提纯方法，该新工艺大大减少了酸的处理时间，并且石英微粉的品质更高：SiO₂含量99．98％、Al₂O₃含量下降到20×10^-6g/g以下、Fe₂O₃含量降到5×10^-6g／g，其它微量元素的含量都低于1×10-^-6g／g。并且，而且在机械-化学提纯的过程中实现了石英的超细粉碎和颗粒预整形，因而石英微粉的流动性能更好，满足了氧气-乙炔火焰法制备球形石英粉对石英微粉的纯度和流动性能的要求。2、研制成功了反应烧结碳化硅球形化炉，改进了沸腾式超细微粉送粉器、火焰燃烧器，开发了氧气-乙炔火焰法球形SiO₂生产新工艺和专用设备。研究了传统送粉器的微粉输送机理，对制约其输送超细微粉所要面临的瓶颈问题进行了分析，指出团聚和流动性差是超细微粉无法输送的关键原因。通过改进粉斗结构、送粉拾取轴、重新设计载气气路，将传统的载气式微粉送粉器改造成沸腾式微粉送粉器，将传统的载气式微粉送粉器改造成沸腾式微粉送粉器。利用空气震动、微粉自身的重力、载气和粉斗内气体的压力差实现了10μm以细的石英微粉和造粒氧化硅微粉的连续、稳定输送。该送粉器的主要技术指标：可送微粉粒度范围为5～50μm，送粉速率为15～200g／min。以反应烧结碳化硅材料为原料，采用实心注浆成型、结合真空烧结工艺制造了球形化炉。对比传统的水冷式夹层不锈钢球形化炉，该球形化炉耐温度更高、并且该设计有效的延长了氧气-乙炔火焰的高温区，整个球形化炉内形成2000K以上的稳定温度场，为获得高球形化率的球形硅微粉提供了保障。对火焰燃烧器的送粉结构进行改进，实现了微粉与氧气-乙炔焰流方向一致的轴向内送粉模式；对比传统的垂直送粉、倾斜送粉等方式，减少了微粉的浪费，并且提高了球形化的效率；通过对喷嘴尺寸进行优化，有效降低了氧气-乙炔焰流速度，轴向内送粉和较低的焰流速度有利于延长微粉在球形化炉内的飞行时间，因而提高了石英微粉的球形化率。氧气-乙炔火焰法球形化工艺中采用O₂作为石英微粉输送时的载气，这部分O₂同样参与助燃，以O₂为载气不会像用其它气体如N₂、Ar一样因为大量冷载气的引入而降低球形化炉的温度。因此，以O₂为载气有效的保持了炉温，有利于提高石英微粉的球形化率。3、建立了石英微粉球形化的数学模型，确定了石英微粉球形化的最佳工艺参数。通过对火焰与石英颗粒热交换、石英颗粒温度变化、石英颗粒速度变化、石英颗粒球形化需要的能量等进行研究，建立了石英微粉球形化的时间模型：式中，t为石英微粉球形化需要的时间，p为石英粉密度，d_p为颗粒直径，H_m为石英的热焓，λ_p表示热火焰燃烧气体的热导率，T_g表示气体的温度，T_p表示颗粒表面的温度，Nu努赛尔数，ε石英的反射率，σ是Stefan Boltzmann常数。研究了氧气-乙炔火焰法球形化石英微粉的实验条件，包括送粉速率、燃气及助燃气的流量、石英微粉的粒度及粒度分布、石英微粉的形貌等因素对微粉球形化率的影响，确定了石英微粉球形化的最佳工艺参数。以中径为10μm的石英微粉为原料进行球形化实验，助燃气O₂ 20L／min、载气O₂ 5L／min、C₂H₂ 10L／min、送粉速率为60g／min，制备的球形石英球形化率可达95％、微粉纯度＞99．9％、松装密度0．87g／cm³、流动度为（67-70）s／50g。石英微粉球形化后平均粒度变大、松装密度变大、流动性能更佳。在氧气-乙炔火焰法球形化石英微粉过程中，低温石英迅速被加热成低温石英的过热晶体，一直保持到1600℃直接熔融为过冷的SiO₂高温熔体，熔体骤冷形成熔融球形石英粉。以氧气-乙炔工艺制备的球形石英粉指标满足大规模集成电路封装的要求，且该工艺制造成本较低，适合于大规模产业化。4、通过实验确定了稻壳为原料制备低放射性球形硅微粉工艺过程中的基本参数。将稻壳在600℃下充分热解得到稻壳灰，利用碱溶液法制备水玻璃，通过优化实验条件，稻壳灰中SiO₂的溶出率为95．74％；以浓度为10％的水玻璃为原料，利用大孔型的D001阳离子交换树脂和D201阴离子树脂交替对其进行交换吸附，制得的硅溶胶的胶粒粒径分布在20～30nm之间、硅溶胶中Na⁺含量为5×10^-6g/g；对固含量为30％的硅溶胶在10mL·min^-1的进料速度下进行喷雾造粒；然后将造粒氧化硅微粉在1000℃下焙烧1h。对上述经焙烧的造粒氧化硅微粉在优化实验条件下进行火焰球形化处理，可以制得球形化率＞95％、颗粒粒度主要分布在1～4μm之间、纯度＞99．99％、放射性元素U含量为0．05×10^-9g/g的低放射性球形硅微粉。这种以稻壳为原料制备的低放射性球形硅微粉满足超大规模集成电路封装的要求。5、利用球形石英粉、低放射性球形硅微粉、普通石英粉三种硅微粉分别填充E-51环氧树脂，其中尤以球形石英粉对E-51的填充量最大，并且制备的球形石英粉／E-51环氧塑封料的热膨胀性能、热稳定性能及力学性能也最优，低放射性球形硅微粉次之。但是，低放射性球形硅微粉在超大规模集成电路封装中更有优势。当球形石英粉的添加量为80％时，环氧塑封料的弯曲强度为146Mpa、环氧塑封料的膨胀系数达到8．5×10^-6K^-1、环氧塑封料的玻璃化温度提高了34℃。采用DSC方法对环氧树脂反应的动力学进行分析，得出SiO₂／E-51／MeTHPA／DMP-30体系固化反应表观活化能△E=78．52kJ·mol^-1，固化反应级数n=0．917。对比射频等离子球形化法、直流电弧等离子球形化法、碳极电弧加热等高温球形化方法、高温熔融喷射球形化法等制备球形硅微粉的方法，氧气-乙炔火焰法球形化工艺更加简化、控制更加容易、能源消耗更少、适于产业化；对比目前正硅酸乙脂或者四氯化硅水解等制备球形硅微粉的化学方法，以稻壳为原料的化学-物理方法结合的工艺简单、产率更高、原料成本更低、可产业化且无污染。因此，氧气-乙炔火焰法制备球形硅微粉更易实现大规模化生产、生产成本更低、更具发展潜力。更多还原

【Abstract】 The paper mainly focused on studying the technique route in producing high-purityspherical silica powder using quartz and rice husk as raw materials. The spherical silica powderas a pivotal filler material has attracted more and more attention in Large Scale Integration （LSI）and ultra Large Scale Integration （VLSI） circuits packaging field with the amazing developmentof micro-electronic industries. In this study a new mechanical-chemical process was employed topurify for obtaining the ultra-fine, pre-shaped and high-purity quartz powder, when quartz rawmaterial was utilized. Otherwise, the rice husk was chosen to prepare low radioactivity sphericalsilica powder. Firstly, rice husk was pyrolyzed to ash that was used to prepare sodium silicate bya basic solution method. Then high-purity colloidal silica was prepared by a cationic-anion resinsalternative exchange process, and Na⁺、K⁺、Al³⁺、Fe³⁺、Cl^- were exchanged. Lastly, theas-prepared colloidal silica was granulated by the spray-drying granulation method, and thegranulation SiO₂ powder was calcined to improve its apparent density and fluidity. A noveloxygen-acetylene flame spheroidization route was employed to prepare spherical silica powders.In the developing technique special equipments were developed, for example, a boiling powdersfeeder, a spheroidization furnace, a flame burner, and so on. After the as-prepared high-purityquartz powder and calcined granulation SiO₂ powder were treated by oxygen-acetylene flame,the high-purity spherical quartz powder used in Large Scale Integration circuits packaging fieldand low radioactivity spherical silica powder used in ultra Large Scale Integration circuitspackaging field were obtained. The two type spherical silica powder and E-51 epoxy werecomposited respectively to prepare epoxy molding compound materials. The glass transitiontemperature, bending strength, linear thermal expansion coefficient of the composites wascharactered.The main achievements of the dissertation are as following: Firstly, structure, appearance, mineral compositions and mineral occurrence of the naturequartz raw material used in this work were studied in detail. Main and micro compositions of thequartz sand were determined quantitatively with chemical and instrumental methods. On the baseof traditional compound acids techniques, a milling and compound acids purifying process wasemployed to prepare high-purity quartz powders. Contrast of the two process, it need shortercompound acids leaching time and could get better purify effects in new mechano-chemistryprocess. At the optimal technique parameters, the content of SiO₂ was more than 99.98 %, thetrace amount of Al₂O₃ lower than 20×10^-6g/g, the total Fe₂O₃ lower than 5×10^-6g/g and theamount of other elements lower than 1×10^-6g/g in the as-purified quartz powders. At the sametime, the quartz raw material was ultra-fine grinding and the powders were pre-shaped by highenergy ball milling in the purify process. The as-shaped ultra-fine powder with good fluidity andpurity performances has met the oxygen-acetylene flame spheroidization process demand.Secondly, special oxygen-acetylene flame spheroidization equipments have been developedand new spheroidization route for quartz powder was founded successfully.The principle of powder transporting on traditional powder feeders was studied in detail andthe bottleneck problem for ultra-fine powder transporting was found. The powdersagglomerations and fluidness were two key reasons. On the basis of the principle of dynamicmechanics and gas dynamics, a boiling ultra-fine powders feeder was improved. The workingprinciple of the feeder accords as the shaking air, gravity of the powder and the pressuredifference between carrying gas and powder hopper. It was capable of feeding angle quartzpowder and granulated SiO₂ powder over a wide range of feed rates from 15g/min to 200g/min,over a wide range of powder size from 5μm to 50μm, regardless of morphology.Using siliconized silicon carbide （SISIC） with high strength, high wear resistance, hightemperature tolerance, high corrosion resistance, high anti-oxidization, high thermal shockresistance as raw material, a spheroidization furnace was designed by the solid grouting moldingand vacuum sintering technology. The reactive sintering silicon carbide is a high temperatureresistant and low linear thermal expansion material. The traditional water-cooling sandwich typespheroidization furnace could only maintain the furnace temperature lower than 1500K. Oncontrast, the new spheroidization furnace could maintain the furnace temperature about 2000K.The higher and stable temperature in the spheroidization furnace ensures a higher spheroidizationrate of the silica powder.Some improvements for the structure and nozzle size of the flame burner with an insidefeeding style had been done. So, the quartz powders could flight in the same direction tooxygen-acetylene flame and powder movement was axial. Because of the nozzle size increasing,the flame flow velocity decreased greatly. Contrast of the traditional vertical and outer feedingstyle or inclined and outer feeding style, one hand, this system could reduce the waste ofpowders, and on the other hand, the holding time of powder in flame burner and spheroidization was increased. Hence the spheroidization rate and the yield of spherical quartz powder wereincreased.The oxygen was chosen as the carrying gas to replace traditional N₂ or Ar during the powdersfeeding in oxygen-acetylene flame spheroidization process. An advantage is obvious in which thecarrying gas oxygen could be used as the assistant gas when acetylene burning. So, nounnecessary cooling gas went to the spheroidization furnace and the high-temperature of furnacecould be kept. It was a positive factor to increasing powder spheroidization rate.Thirdly, a mathematical model of the quartz powder spheroidization was established and themost efficient quartz powders spheroidization process parameters were determined.A heat energy transfer between the flame and powders, a temperature variation rule of thepowder, a speed variation law of the powder and the minimum energy of quartz spheroidizationwere studied in detail. And the mathematical model of quartz powder spheroidization wasestablished as:Where P is the particle density, t is the time required for spheroidization, dp is the powder size,H_m is the enthalpy of silica,λ_p is the thermal conductivity of gas, T_g is the gas temperature, T_p isthe powder temperature, Nu is the Nusselt number,εis the emissivity of silica powder andσisthe Stefan Boltzmann constant.During the preparation process of spherical quartz powder, the influencing factors tospheroidization rate, for example, the feeding rate, the flow rate of burning gas and assistant gas,the pressure of burning gas and assistant gas, the frequency of shaking gas, the size and sizedistribution of quartz powder, the morphology of the powder were studied. At optimumspheroidization technological parameters, the flow rate of burning gas 10L/min, the flow rate ofassistant gas 20L/min, the flow rate of carrying gas 5L/min, the feeding rate 60g/min, thehigh-purity quartz powders with the average size 10μm were treated by oxygen-acetylene flame.And, the spheroidization rate of the as-prepared spherical powder sample was 95%, the purity ofthe sample more than 99.9%SiO₂, the apparent density 0.87g/cm³ and the fluidity from 67/50g to70s/50g. After spheroidization, the average size of sample was bigger, the size distributionnarrower, the powder denser, the surface of the powder smoother and the fluidity better.Fourthly, a low radioactivity spherical silica powder using the rice husk as the raw materialswas obtained by a chemical-physical method and the basic process parameters were optimized.The rice husk was pyrolyzed fully at 600℃and the ash was used to prepare sodium silicate bya basic dissolving method. The most efficient decomposition can be obtained when the ratio of ash to the sodium hydroxide solution （20% in W/V） weight is 1:3, the temperature wascontrolled at 140℃, and the heating time was lasted for 4 hours. At these conditions theconversion rate of the SiO₂ in rice husk exceeded 95%. During the preparation procedures ofhigh-purity colloidal silica, the method and technique of exchanging Na⁺, K⁺, Al³⁺, Fe³⁺ and Cl^-from the sodium silicate were investigated in details.The cationic-anion resin alternative exchange was an efficient type, the particle size ofcolloidal silica is from 20 to 30nm and the amount of Na⁺ is lower than 5×10^-6g/g. Then, thecolloidal silica with the solid content of 30% was granulated by the spray-drying granulationmethod with the feeding rate 10mL/min. Because of the hollow-core structure of granulationSiO₂ powders, the apparent density was lower and the fluidity was insufficient. To improve theseproperties, the granulation SiO₂ powders was calcined at 1000℃for 1 hour. At last, the calcinedSiO₂ powders were treated by the oxygen-acetylene flame, and the spheroidization rate of thelow radioactivity spherical silica powder sample was more than 95%, the purity more than99.99%, the size distributed from 1～4μm and the content of U 0.05×10^-9g/g.Fifthly, the Epoxy Molding Compounds （EMC） was prepared separately by both themechanical disperse and the ultrasonic disperse using the spherical high-purity quartz powder,the low radioactivity spherical silica powder and the common quartz powder as the fillers. Inwhich, filling amount of spherical high-purity quartz powder was 80%, more than two otherpowders, and Epoxy Molding Compounds’ properties were the best. But, for the higher purityand lower radioactivity of low radioactivity spherical silica powder, it had obvious advantage asthe filling materials in the ultra Large Scale Integration circuits packaging field. When the fillingamount of spherical high-purity quartz powder was 80%, the Epoxy Molding Compounds’bending strength was 146 MPa, the linear thermal expansion coefficient 8.5×10^-6K^-1 and theGlass transition temperature increasing 34℃. The Differential Scanning Calorimetric （DSC）,Kissinger equation and Ozawa equation were employed to detect the kinetics of co-curing system.The apparent reactive activation energy （△E） of spherical quartzpowder/E-51/MeTHPA/DMP-30 was 78.52kJ/mol, and the order of reaction n=0.917. Using thespherical quartz powder and low radioactivity spherical silica powder as the fillers, the linearthermal expansion coefficient was greatly reduced and the thermal stability was improved, whilethe mechanical properties were maintained.On the whole, a new oxygen-acetylene flame spheroidization quartz powder and calcinedgranulation SiO₂ powder was developed and a series of special equipments were developed. Inwhich, the rice husk was used as the raw material to prepare the low radioactivity silica powderin the first time. The experimental conditions and technique parameters were optimized with thedetection of results and processes by analytical instruments. Recent researches and developmentsof actuality in the China and international spherical silica powder of actuality produced werebrief reviewed. Several processes and their features for spherical quartz powder, for example, the high temperature fused quartz jet process, the high frequency plasma spheroidization process, thedirect current arc plasma spheroidization process and the carbon electrode high-temperaturespheroidization process were analyzed and compared. The oxygen-acetylene flamespheroidization process is a simple-equipment, easy-control and lower energy cost process.Contrast of the traditional ethyl orthosilicate or silicon tetrachloride hydrolysis methods for lowradioactivity spherical silica, the chemical-physical process taking the rice husk as raw materialwas a higher yields, a lower raw materials cost, a nontoxic and easy industrial production method.Therefore, the oxygen-acetylene flame spheroidization process has advantages over some othermethods and it should be a potential cost-effective process for mass production of spherical silicapowder. Besides, this method can be expanded to preparation of many other spherical powders.更多还原