单分散聚合物/金属复合导电微球的尺寸结构设计与控制及在各向异性导电胶膜（ACF）中的作用机制

Anisotropic conductive adhesive film (ACF) is a kind of green packaging bonding material, which is consisted of epoxy resin and polymer/metal composite conductive microspheres. ACF has attracted more and more attention in microelectronic field due to its advanced bonding capabilities of high density, narrow spacing between devices and circuits. However, its application effect was limited due to its disadvantages such as high contact resistance, high possibility of short circuit and open circuit faults, poor resistance to low temperature. In this study, a kind of flexible molecule (e.g. butyl acrylate) was introduced into the interior of conductive microspheres to decrease the glass transition temperature of polymer microspheres, and increase the elasticity of conductive microspheres, which was useful for increasing the contact area and strength of conductive microspheres between devises and circuit. This approach can reduce the contract resistance of ACF bonding. In addition, a SiO2 insulating layer was constructed on the surface of conductive microspheres using self-assembly method to prevent short circuit and open circuit faults by promoting the compatibility of conductive microspheres in resin. The cross-linked polymer layer along with special groups containing phosphorus was constructed on the surface of polymer microspheres to adjust the Poisson's ratio and interfacial bonding force of conductive microspheres, further preventing breakages of metal layers under low temperature or high pressure conditions. The aim of this project can be concluded as following: (1) To ensure the working process and mechanism of conductive microspheres in ACF bonding process. (2) To discuss the effect of the structure or diameter of conductive microspheres to reliability of ACF bonding. (3) To invent a kind of new method to prepare conductive microsphere. (4) To provide scientific theories for developing high quality ACF. At last, this project can provide a new idea to solve the troublesome issue of economy development suggested by government.

各向异性导电胶膜（ACF）是由聚合物/金属复合导电微球掺杂环氧树脂经初步固化成膜而制备的新型绿色封装材料，因具备高密度、窄间距的连接能力而备受微电子工业青睐，但却因耐低温性能差、接触电阻高、易断路和短路等原因而影响应用效果。本申请课题从分子设计角度出发，通过向导电微球内部引入柔性分子的方法增强导电微球回弹性，从而增大导电微球与接触点间的接触面积和强度，降低ACF连接接触电阻；并利用自组装方法在导电微球表面吸附SiO2绝缘层，构筑空间位阻，改善导电微球与基体树脂间相容性，降低ACF断路和短路风险；采用构建交联网络、共聚磷系单体的方法调控导电微球泊松比和界面结合力，解决导电微球金属层易剥离、破碎问题，提高ACF连接可靠性。进而探究导电微球在ACF中的作用机制，阐明微球尺寸结构与ACF可靠性间关系，构建导电微球制备新途径，为开发高性能ACF提供理论基础和科学依据，为解决“卡脖子”问题提供思路。

各向异性导电胶膜（ACF）是由聚合物/金属复合导电微球掺杂环氧树脂经初步固化成膜而制备的新型绿色封装材料，因具备高密度、窄间距的连接能力而备受微电子工业青睐，但却因耐低温性能差、接触电阻高、易断路和短路等原因而影响应用效果。本项目以制备ACF中的导电微球为出发点，系统地研究了单分散聚合物金属核壳复合微球的形成机理以及制备工艺。首先通过使用一步法分散聚合制备了单分散聚苯乙烯（PS）微球。然后以PS微球为模板球，采用化学镀法制备了PS-Ni金属核壳复合微球。讨论了镀液中各组分包括还原剂浓度、络合剂浓度、主盐浓度、化学镀实施方式以及PS微球在化学镀液中的装载量对金属核壳复合微球表面微观结构与形貌的影响。得到的最佳工艺条件为：超声波辅助下进行机械搅拌、主盐浓度为0.2 M，络合剂浓度为0.07 M，还原剂浓度为0.23 M。 通过使用改进后的化学镀法制备了PS-Ag金属核壳复合微球。相比于传统化学镀，活化使用尺寸更小的铂（Pt）代替钯（Pd）用来启动化学镀，使Ag壳的致密性及完整度得到改善。此外，还探讨了化学镀Ag过程中镀覆温度、时间以及PS微球装载量对PS-Ag金属核壳复合微球表面微观结构与形貌的影响。得到的最佳工艺条件为：镀覆温度为15 ℃、时间为60 min、PS微球装载量为4 g/L。以环氧树脂（EP）为基体树脂，环境友好的聚酰胺树脂为固化剂，端羧基液态丁腈橡胶（CTBN）为增韧橡胶以及各种助剂开发了ACF的粘合剂体系。根据固化动力学预测了最佳固化工艺参数。通过计算后得出：固化温度为136 ℃、固化时间为11 min。其次，借助超声波水浴，将PS-Ag、PS-Ni复合微球与增韧后的环氧树脂通过物理掺混构建了各向异性导电胶膜。由于各向异性的导电阵列中存在导电性能优良的金属核壳复合微球构成的亚微米结构，ACF在自制的试件中呈现出优异的各向异性电性能。

内容获取失败，请点击重试