【作者】 吕静；

【导师】 党智敏；

【作者基本信息】 北京化工大学 ， 材料科学与工程， 2011， 硕士

【摘要】 随着集成电路产业的发展,高性能微电子封装技术已形成与集成电路产业相适应的高新技术产业。对电子封装材料来讲,较低的热膨胀系数和良好的高频特性(即较低的介电常数和介电损耗)是两个重要的指标。聚酰亚胺(PI)具有优良的机械、介电、电绝缘、耐高温、耐腐蚀等性能,综合性能优异,应用于电子塑料封装材料前景良好。本文首先用直接固相法和分步固相法两种方法合成出了纯度较高的原料钨酸锆(ZrW208)粉末,粒径在5～10μm左右,平均热膨胀系数为-9.604×10-6 K-1。然后分别以合成的ZrW208粉末和纳米碳化硅(n-SiC)作为填料,采用原位聚合法制备出了ZrW208/PI和n-SiC/PI两种复合薄膜,用扫描电子显微镜(SEM)、热机械分析仪(TMA)、阻抗分析仪和热重分析(TG)研究了所制备薄膜的表面形貌、热膨胀性能、介电性能及热稳定性。结果表明：(1)ZrW208粒子均匀的分散在PI基体中,且ZrW208的加入降低了复合薄膜的热膨胀系数(CTE), ZrW2O8含量越高,复合薄膜的CTE越小；热循环次数对CTE的影响不大,制备出的PI膜具有很好的尺寸稳定性。ZrW208/PI复合薄膜的介电常数随着填料含量的增加而小幅度增加,介电损耗随填料含量的增加变化较小,两者始终维持在较低的范围内,且在相当大的频率范围内保持稳定,对温度的依赖性不大。随着ZrW208含量的增加,复合薄膜的热稳定性增加,力学性能虽有小幅下降,但仍维持在较高水平。通过对ZrW2O8改性后的研究表明,改性后的ZrW208在PI基体中分散更均匀,得到的ZrW2O8/PI复合薄膜的CTE更小,介电常数和介电损耗也相应降低。(2) n-SiC粒子均匀分散在PI基体中,复合薄膜的CTE随着n-SiC含量的增加逐渐减小,n-SiC为15wt%时,CTE降低了11%,且复合薄膜的热膨胀系数实验值比较接近于以Kerner公式的计算值。复合薄膜的介电常数和介电损耗随着填料含量的增大而有小幅度增加,但始终维持在较低的范围内,而且在相当大的频率和温度范围内保持稳定。相对于纯PI,n-SiC/PI复合薄膜的热稳定性也有所提高。两种PI复合薄膜均具有低热膨胀系数、低介电常数、低介电损耗(温度、频率稳定性)、较高的热稳定性等性能特点,能够很好的应用于电子封装材料。更多还原

【Abstract】 With the development of the integrated circuit industry, high-performance microelectronic packing technology has formed high-tech industries compatible with IC industry. In terms of electronic packaging materials, low thermal expansion coefficient and good high frequency characteristics (ie. low dielectric constant and dielectric loss) are two important indicators. Polyimide (PI) has good prospects in electronic plastic packaging materials for its excellent mechanical、dielectric、electrical insulation、marked thermal stability and corrosion resistance properties.In this study, the high purity zirconium tungstate (ZrW2O8) powders have synthesized by two methods:direct solid-state reaction and step by step solid-state reaction, with the average size of 5～10μm and the average coefficient of thermal expansion of -9.604×10-6K-1.And then selecting the synthetic ZrW2O8 and n-SiC as fillers, ZrW2O8/PI and n-SiC/PI composite films were prepared by in-situ dispersive polymerization separately. The surface morphology, thermal expansion, dielectric properties and thermal stability of ZrW2O8/PI and n-SiC/PI composite films were studied by scanning electron microscopy (SEM), thermal mechanical analysis (TMA), impedance analyzer and thermal gravimetric analysis (TG) respectively. The following are the results:(1) ZrW2O8 particles are dispersed in the PI evenly, and the input of ZrW2O8 decreases the CTE of composite films. The higher ZrW2O8 content, the smaller the CTE; number of thermal cycles has little effect on the CTE, so the prepared PI films has good dimensional stability. The dielectric constant of ZrW2O8/PI composite films increases slowly with the content of filler, and the dielectric loss changes little with increasing content of filler, remaining in the lower range, and both of them are stable in a wide frequency range and have little dependence on temperature. With the increase of ZrW2O8 content, the thermal stability of composite films increases, while the mechanical properties of composite films decreases slightly, and still remaining in the higher range. Using KH550 to modify ZrW2O8, the modified ZrW2O8 disperses in the PI matrix more uniformly, resulting in smaller CTE、lower dielectric constant、lower dielectric loss of ZrW2O8/PI composite films.(2) n-SiC particles are dispersed in the PI matrix evenly by employing the in-situ polymerization. The coefficient of thermal expansion (CTE) of n-SiC/PI composite films decreases with the increasing the SiC loading, while the experimental data could be analyzed by Kerner model closely. The CTE of PI with n-SiC mass fraction of 15% is about 11% decrease than that of the pure PI. The dielectric constant and dielectric loss of films increase slowly with the content of n-SiC fillers, remaining in the lower range and stable in both a wide frequency range and a wide temperature range. Compared with the pure PI, the thermal stability of n-SiC/PI composite films has improved.Both PI composite films have low coefficient of thermal expansion, low dielectric constant, low dielectric loss (temperature、frequency stability), high thermal stability and other performance characteristics, can be well applied in electronic packaging materials.更多还原