低介电常数聚酰亚胺材料制备方法研究进展

介绍了几种制备低介电常数聚酰亚胺(PI)材料的方法及其研究进展,包括引入氟原子降低极化率、引入硅氧烷增大自由体积、引入孔洞降低密度以及多种方法相结合共同降低介电常数等,指出了低介电常数PI制备方法的未来发展方向。     

低介电常数聚酰亚胺薄膜的研究进展

低介电常数的聚酰亚胺薄膜在解决超大规模集成电路所引起的RC延迟、串扰、能耗、噪声等问题中有着关键性的作用。文章综述了近几年来国内外低介电常数聚酰亚胺薄膜的制备方法,详细介绍了引入纳米多孔结构、改变聚酰亚胺本体结构以及填充低介电材料这三种研究方法,并对各种方法的优缺点做了简要评价。     

聚倍半硅氧烷/聚酰亚胺复合材料制备及性能研究

本文以4,4'-二氨基二苯醚、均苯四甲酸二酐为原料,制备聚酰亚胺(Polyimide,PI)薄膜。并将其与笼型倍半硅氧烷(Polyhedral oligomeric silsesquioxane,POSS),通过原位分散聚合法制备了具有低介电常数POSS/PI复合薄膜。研究了POSS填充量对POSS/PI复合材料介电、热稳定性及力学性能的影响。结果表明:掺入POSS的含量为0.5wt%时,POSS/PI复合材料的介电常数与介电损耗明显降低,热分解温度变化不大,拉伸强度略有降低。     

无色透明聚酰亚胺薄膜研究进展

介绍了国内外无色透明聚酰亚胺(PI)薄膜材料的研究现状,重点综述了含氟芳香族和脂环族两大类PI薄膜的研究进展,包括引入含氟取代基、主链引入脂环结构、非平面共轭结构、引入砜基等方法制备无色透明材料。同时,概述了国内外无色透明PI薄膜的产业化现状,并对无色透明PI薄膜的发展趋势进行了展望。     

超低介电常数聚酰亚胺的开发及应用

介绍了超低介电常数聚酰亚胺（PI）的研究开发情况。指出通过合成PI与热不稳定聚合物进行嵌段、接枝共聚制备的PI纳米泡沫材料是一种可用于微电子工业的极富应用前景的低介电常数材料，并对其在微电子工业中的应用作了简要叙述。     

低介电聚酰亚胺复合片材的结构设计与性能研究

基于夹层结构设计,在聚酰亚胺（PI）薄膜夹层间引入多孔聚酰亚胺泡沫（PIF）,成功制备具有低介电常数的PI复合片材,并研究PIF厚度对复合片材介电性能、力学性能和导热性能的影响。结果表明：介电常数随着PIF厚度的增加而增加,厚度为1 mm的复合片材的介电性能最佳,100 Hz下介电常数低至1.55。随着PIF厚度的增加,复合片材的拉伸强度降低,导热系数先降低后趋于平缓。FFF-15-5样品的导热系数最低为0.046 W/（m·K）,复合片材显示良好的隔热性能。该PI复合片材为低介电材料的设计提供新思路。     

聚酰亚胺PI／SiC纳米复合材料的制备及特性

通过熔胶-凝胶方法合成了用于电子封装的聚酰亚胺PI/SiC复合薄膜介电材料,并通过扫描电镜、透射电镜、红外光谱对复合薄膜进行结构表征。结果表明,聚酰亚胺PI／SiC复合材料是一种共聚物,是纳米SiC粒子均匀分散在PI基体中的复合材料体系。在4284A型阻抗分析仪上测量了材料的电容,并换算出相应介电常数,最低达ε=2．0。     

“高分电常数低损耗复合电介质薄膜”成果通过鉴定

由天津大学材料科学与工程系承担的天津市21世纪青年科学基金项目“高介电常数低损耗复合电介质薄膜”,日前通过了由天津市科委组织的技术鉴定。高介电常数低损耗复合电介质薄膜可用于制造大容量、小体积、高可靠性电容器。这项研究采用高介陶瓷与目前生产薄膜电容器常用的高分子材料复合的方法,利用两种材料各自的优势,制备出高介电常数、低损耗复合电介质薄膜。重点解决     

黑色聚酰亚胺薄膜研究进展

介绍了国内外黑色聚酰亚胺（PI）薄膜材料的研究现状,重点综述了绝缘、抗静电、导电及导热4大类黑色PI薄膜的研究进展,包括引入导电或非导电炭黑颜料、无机或有机类消光剂、陶瓷类填料等材料以及采用预处理、共混或原位聚合的方式制备黑色PI薄膜。同时,概述了国内外黑色PI薄膜的产业化现状,并对黑色PI薄膜的研究趋势进行了展望。     

含杂环结构的耐高温聚酰亚胺薄膜

聚酰亚胺(PI)薄膜具有高耐热,高力学性能,低热膨胀系数等优异的综合性能,广泛应用于光伏、微电子、航天航空等领域。探索制备具有更高热稳定性的PI具有重大的应用价值,但是也存在极大挑战。本文介绍了PI的分子设计和合成,综述了耐高温PI薄膜的制备方法以及纳米复合材料改性PI薄膜热稳定性的制备,阐述了近年来PI薄膜在柔性光电器件方面的应用。最后,展望了耐高温PI薄膜未来的发展趋势及需要解决的关键问题。     

Water diffusion studies in polyimide thin films

The water diffusion behaviors and activation energies of PDA- and ODA-based polyimide thin films were quite dependent on both the chemical structure and the morphological structure in the films. The water diffusion coefficients of polyimide thin films increased with increasing temperature. The activation energies varied in the range of 5.81 to 9.27 kcal/mol and were relatively higher for the PDA-based polyimide thin films than for the corresponding ODA-based polyimide thin films. For the PDA- and ODA-based polyimide films, the differences in the morphological structures and the chemical affinity to water molecules might be reflected directly on the water diffusion behaviors. The PDA-based polyimide films exhibited a relatively more ordered morphological structure (high crystallinity and good in-plane orientation) than that of the corresponding ODA-based polyimide thin films, which may serve as impenetrable obstacles for the water diffusion in the out-of-plane direction. Consequently, it may lead to a relatively slower water diffusion and high activation energy in the PDA-based polyimide thin films. Additionally, the PDA-based polyimide films with relatively lower chemical affinity showed relatively low diffusion coefficients and high activation energies. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 731–737, 2001     

Polyimide blend alignment layers for control of liquid crystal pretilt angle through baking

Polyimide films were used for liquid crystal (LC) alignment layers to control LC pretilt angles over the full range (8°-90°). The pretilt angles could be controlled using polyimide films prepared from polyamic acid for vertical LC alignment and using polyimide blend films prepared from two types of polyamic acids, one for vertical LC alignment and the other for planar LC alignment, by changing the baking times ranging from 40 to 180 min at 230 °C. The polyimide blend film could control the pretilt angle better than the polyimide prepared from just one polymer component. The LC alignment behavior was well correlated with the wettability of the polyimide films due to the fragmentation of the long alkyl side group on the polyimide surfaces by the baking process.     

高温热处理对聚酰亚胺薄膜性能的影响

研究了高温热处理对聚酰亚胺(PI)薄膜拉伸性能和热性能的影响。在薄膜完全环化后,随着热处理温度的升高,薄膜的拉伸强度、弹性模量先增大后基本保持不变,断裂伸长率先保持不变后明显降低,热膨胀系数也显著降低,而薄膜的玻璃化转变温度略有增大。高温热处理工艺可制备高强度和低热膨胀系数的高性能PI薄膜。     

Indentation test for adhesion measurement of polyimide films

An indentation technique was used to determine the adhesion of polyimide films on a ceramic substrate. Experimental results were obtained by indenting 13 μm thick polyimide films with a conical indenter at different indentation loads. Among the process variables investigated were the amount of adhesion promoter added to the polyimide and the exposure to temperature and humidity. The technique provides a measure of the bond strength, based on the analysis of indentation debonding of thin films. For well adhered films, no debonding could be induced, indicating the usefulness of the test only for the poorly bonded films.     

Effect of metal halides on thermal,mechanical, and electrical properties of polypyromellitimide films

This paper describes the effect of metal halides (Co²⁺, Sn²⁺, and Hg²⁺) on the properties of polyimides. Low temperature, solution polycondensation reaction of pyromellitic dianhydride and 4,4′-diaminodiphenyl ether was used for preparation of a poly(amide-acid) solution in dimethylformamide ([η] = 2.0 dL/g). Films containing 1% (w/w) of cobalt (II) chloride, tin (II) chloride, and mercury (II) chloride were prepared by solution casting of poly(amide-acid) from the DMF solution. Cyclodehydration to polyimide was done by heating the films in nitrogen atmosphere for one hour each at 100°, 200°, and 250°C. The color of the films depended on the dopant and was yellow (HgCl₂ or SnCl₂) or green (CoCl₂) Higher percentage weight loss was observed in doped films in nitrogen atmosphere in the temperature range of 250–400°C. No significant difference in thermal behavior of doped and undoped films was observed above 500°C. Doping reduced the tensile strength of polyimide films, maximum reduction was observed in CoCl₂-doped film. The electrical conductivity of polyimide films as a function of temperature and field was studied. Undoped polyimide showed ohmic behavior up to 150°C. In doped films at lower voltages Poole-Frenkel mechanism was operative, while at high voltages Richardson-Schottky's mechanism was operative. Dielectric relaxation in polyimide films was also studied.     

Thermoanalytical investigation of transformation of polyamido acid into polyimide

The effect of solvent and schedules of treatment of solutions of polyamido acid synthesized from diaminodiphenylic ether and pyromelitic dianhydride on its transformation into polyimide, and the effect on thermal characteristics of the latter, has been investigated by simultaneous thermogravimetric and differential thermal analysis. It was shown that dimethyl-formamide strongly affects the formation and properties of polyimide film. Optimum conditions of preparation of polyimide films were determined with the authors' taking into account the high reactivity of dimethylformamide. A possibility of using a water-acetone mixture as a medium for the preparation of polyimide films was shown.     

The effect of different orientations in rigid rod polyimide films on the graphitized products

The effect of uniaxial and in-plane orientation of different rigid-rod homo- and co-polyimide films on the development of graphite structure after heat treatment up to 3070 K was investigated. The magnetoresistance and X-ray diffraction measurements were carried out to estimate the degree of graphitization and in-plane orientation of graphite crystallites. Both pristine and in-plane pre-oriented polyimide films show high degrees of graphitization. In-plane cold-drawing leads to the increase of in-plane orientation of polyimide films, but it produces the different actions on the graphitization parameters of homo- and co-polyimide films. While the cold pre-drawing of homo-polyimide films increases their graphitizability, this pre-treatment of the co-polyimide films does not lead to the improvement of graphitized material’s characteristics. The uniaxial orientation results in the hindrance of graphitization. The role of the supramolecular structure of ordered regions of polyimide films in the development of graphite structure under graphitization process has been discussed.     

Residual stress and mechanical properties of polyimide thin films

Four different structure polyimide thin films based on 1,4‐phenylene diamine (PDA) and 4,4′‐oxydianiline (ODA) were synthesized by using two different dianhydrides, pyromellitic dianhydride (PMDA) and 3,3′,4,4′‐biphenyltetracarboxylic dianhydride (BPDA), and their residual stress behavior and mechanical properties were investigated by using a thin film stress analyzer and nanoindentation method. The residual stress behavior and mechanical properties were correlated to the morphological structure in polyimide films. The morphological structure of polyimide thin films was characterized by X‐ray diffraction patterns and refractive indices. The residual stress was in the range of ?5 to 38 MPa and increased in the following order: PMDA‐PDA < BPDA‐PDA < PMDA‐ODA < BPDA‐ODA. The hardness of the polyimide films increased in the following order: PMDA‐ODA < BPDA‐ODA < PMDA‐PDA < BPDA‐PDA. The PDA‐based polyimide films showed relatively lower residual stress and higher hardness than the corresponding ODA‐based polyimide films. The in‐plane orientation and molecularly ordered phase were enhanced with the increasing order as follows: PMDA‐ODA < BPDA‐ODA < BPDA‐PDA ～ PMDA‐PDA. The PDA‐based polyimides, having a rigid structure, showed relatively better‐developed morphological structure than the corresponding ODA‐based polyimides. The residual stress behavior and mechanical properties were correlated to the morphological structure in polyimide films. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Porous polyimide films obtained by using lithium chloride as pore‐forming agent

Porous polymer films have been obtained from polyimide based on benzophenonetetracarboxylic dianhydride and 4,4'‐diamino‐3,3'‐dimethyl‐diphenylmethane by incorporating lithium chloride (LiCl) in the poly(amidic acid) precursor and subsequently leaching out the maximum possible LiCl by water Soxhlet extraction for 6 h. The resulting porous polyimide films were characterized with regard to their pore size, thermal stability and dielectric properties. The morphology of the porous polyimide films showed a uniform distribution and various pore sizes depending on the initial quantity of added pore‐forming agent. © 2013 Society of Chemical Industry     

Water sorption behaviors of the BPDA‐based polyimide films depending upon the structural isomers of diamine

For the biphenyltetracarboxylic dianhydride (BPDA)‐based polyimide thin films, the water sorption behaviors were gravimetrically investigated by using a thin film diffusion analyzer. The water sorption behaviors of the polyimide thin films are quite different and strongly dependent upon the sort of polyimide. The diffusion coefficients of the polyimide thin films vary in the range of 1.6 × 10⁻¹⁰ to 12.4 × 10⁻¹⁰cm²/s and the water uptakes vary from 1.52 to 5.25 wt %. Both the diffusion coefficient and water uptake of the polyimide thin films are in the increasing order: BPDA‐pPDA < BPDA‐p,p′ODA < BPDA‐p,m′ODA < BPDA‐mPDA ∼ BPDA‐p,p′DDS < BPDA‐m,m′DDS. Specifically, the polyimide films with para‐oriented linkages in backbone structure showed relatively lower diffusion coefficient and water uptake than the corresponding polyimide films with meta‐oriented linkages because of the well‐developed crystalline structure and good intermolecular chain ordering. In addition, the polyimide thin films having higher chain order showed relatively lower diffusion coefficient and water uptake. The crystallinity and intermolecular chain ordering in the morphological structure are critical parameters in controlling the water sorption behaviors of the polyimide thin films. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 2121–2127, 2001