【作者】 徐伟；

【导师】 徐桂芳；

【作者基本信息】 江苏大学 ， 材料加工， 2007， 硕士

【摘要】 环氧树脂具有良好的粘着性、电绝缘性、耐湿性、化学稳定性和电学性能，从而在电子封装领域得到广泛的应用，约占整个塑料封装90％左右。器件和集成电路用环氧树脂封装成型后，由于器件和封装材料线膨胀系数的差异，成型固化收缩导致封装材料器件内部产生热应力，造成强度下降、耐热冲击性降低、老化开裂、封装裂纹、空洞、钝化和离层等各种缺陷。近年来材料学家发现多种负热膨胀（Negative Thermal Expansion，NTE）材料，其中以立方晶体结构的ZrW₂O₈为代表，具有各向同性负热膨胀效应，在较宽的温度区间内（0．3K～1050K），具有基本恒定的负热膨胀系数。本文以分析纯ZrO₂和WO₃为原料，采用固相分步法制备负热膨胀材料ZrW₂O₈粉体，利用其负热膨胀的特性，以ZrW₂O₈粉体作为填料，在不同填料比例下，采用钛酸三异丙醇叔胺酯（706）作为固化剂，2．4．6-三（二甲胺基甲基）苯酚（DMP-30）作为促进剂，制备ZrW₂O₈/E-51和SiO₂／E-51电子封装材料，并对所制备封装材料的组织、结构、性能及动力学进行了研究分析。对固相化学分步法合成的ZrW₂O₈粉体，采用扫描电镜SEM、XRD、变温XRD分析，结果表明ZrW₂O₈粉体的粒径介于0．5～1μm之间，纯度高；在20℃～700℃的区间内，平均线膨胀系数为-5．33ppm／K，具有负热膨胀特性。SEM分析表明，超声波处理能使SiO₂和ZrW₂O₈粉体均匀分散在环氧树脂E-51基体中。采用DSC分析材料的玻璃化转变温度，结果表明在相同添加量下，SiO₂／E-51的玻璃化转变温度与ZrW₂O₈/E-51相当；随着ZrW₂O₈颗粒填充量的增加，ZrW₂O₈/E-51材料的玻璃化转变温度随之提高，当ZrW₂O₈以质量比1：1填充E-51时，玻璃化转变温度达到147．87℃。填料的加入大幅度的降低了环氧树脂封装材料的线膨胀系数，由于ZrW₂O₈颗粒的负热膨胀特性，相同添加量下，ZrW₂O₈／E-51体系较SiO₂／E-51体系线膨胀系数下降了14．5％，随着ZrW₂O₈添加量的提高，ZrW₂O₈/E-51封装材料的线膨胀系数进一步降低。相同填充量下，ZrW₂O₈/E-51的介电常数高于SiO₂／E-51，介质损耗更低；随ZrW₂O₈含量的增加，ZrW₂O₈／E-51材料的介电常数ε_r不断提高，介质损耗不断下降。当ZrW₂O₈与E-51的质量比为0．7：1时，封装材料的介电常数达到最大；当ZrW₂O₈与E-51的质量比为1：1时，封装材料的介电常数有所下降。阻温特性表明在室温～163℃范围内，ZrW₂O₈/E-51材料的体积电阻率稳定在3．03×10⁶Ω·m，较SiO₂／E-51材料提高了10％左右。室温下，ZrW₂O₈／E-51及SiO₂／E-51电子封装材料击穿场强均大于10KV／m，满足微电子器件封装材料的实际应用。相同填充量下，ZrW₂O₈／E-51的力学性能优于SiO₂/E-51。当ZrW₂O₈以质量比1：1填充E-51时，ZrW₂O₈／E-51的拉伸、弯曲强度分别达到99MPa、158MPa，较1：2填充E-51时增加了15％、13．9％。SiO₂／E-51及ZrW₂O₈／E-51封装材料的显微硬度较纯环氧树脂有所提高。当ZrW₂O₈填充量增加时，ZrW₂O₈／E-51的硬度也随之增加，加入量增加到一定程度后，表面硬度略有下降。ZrW₂O₈粉体填充环氧树脂，材料耐酸性得到提高。当ZrW₂O₈与E-51按照质量比0．7：1混合时，固化物的耐湿性较好。ZrW₂O₈／E-51材料的磨损性能优于SiO₂／E-51材料，在水润滑条件下，磨损系数和磨损率与干磨损相比大幅度下降；随着试验时间的增加，磨痕宽度变宽，磨痕的表面形貌越粗糙，比磨损率越来越小。采用动态DSC分析，研究了E-51封装体系反应固化动力学，根据Kissinger方程和Crane方程计算出SiO₂／E-51／706及ZrW₂O₈／E-51／706两体系的的表观活化能△E分别为：83．2KJ／mol和70．6KJ／mol，反应级数n分别为：0．9236和0．9234，确定了两体系的反应速率常数K。更多还原

【Abstract】 Epoxy resin has been wisely used in electronic packaging industries due to its ease of processing, low cost, excellent heat, moisture, and chemical resistance, superior electrical and mechanical properties, and good adhesion to many substrates. However, current organic based board materials such as epoxy resins are not suitable to meet the electronic industry requirement because of two main limitations; lack of board dimensional control because of war-page and distortion during the thermal cycling and the large coefficient of thermal expansion （CTE） mismatch between the substrate and silicon chip leading to solder joint failures. Upon cured, this multifunctional epoxy resin provides a densely crosslink protective layer; however, because of the difference in linear expansion coefficient between filler and epoxy resin, some imperfections are bora to molding compounds during curing, such as point defect, bulk, season cracking, etc.Negative thermal expansion （NET） materials have received considerable attention during the last decade. Cubic zirconium tungstate, ZrW₂O₈, has been used as an additive to control the thermal expansion properties of composite materials due to its relatively large isotropic, negative thermal expansion. Admixture of ZrW₂O₈ into cement, polyester, or epoxy polymers make composites exhibiting reduced thermal expansion properties. This article reported the synthesis of ZrW₂O₈ by solid-state reaction using chemical synthetic ZrO₂ and WO₃ as starting materials, and the fabrication of ZrW₂O₈/epoxy resin （E-51） polyimide electronic packaging materials in which the embedded filler particles appear to be in close contact with the polymer phase.Adopting High-low temperature diffraction and the Powder X software calculation, the average linear expansion coefficient of ZrW₂O₈ particle was about -5.02×10ppm/℃. Sample of SEM imaging showed the average particle diameter of ZrW₂O₈ synthesized by solid-state reaction was about 0.5～1μm.Compared with SiO₂/E-51 composites, ZrW₂O₈/E-51 has the better tensile strength, flexural strength and anti-acid property. With more ZrW₂O₈ content, ZrW₂O₈/E-51 composites showed a decline in linear expansion coefficient and an increase in the mic-hardness. The results show that, with more ZrW₂O₈ content, the dielectric constant of ZrW₂O₈/E-51 increase, whereas the dielectric loss decline gradually. During room temperature and 163℃, ZrW₂O₈/E-51 composites show a steady bulk resistivity about 3.03×106Ω·m, and its breakdown field strength is in excess of 10KV/m, which is available to industry application. The wear mechanism of packaging materials of epoxy resin is adherence abrasion and abrasive wear. However, the moisture absorption rate and anti-alkali property were worse than those of SiO₂/E-51 composites.Differential scanning calorimetric （DSC）, Kissinger equation and Ozawa equation were employed to detect the kinetics of co-curing system. The apparent reactive activation energy （ΔE） of SiO₂/E-51/706 and ZrW₂O₈/E-51/706 was 83.2 KJ/mol and 70.6 KJ/mol, respectively. Also the velocity constant of the two reactions were measured.更多还原