超低消散因子之聚醯亞胺結構開發與性質探討

Investigation on the Properties and Structures of Polyimides with Ultra low Dissipation Factor

陳宇哲(Yu-Che Chen)

指導教授 ： 陳文章

國立臺灣大學/工學院/化學工程學研究所/碩士(2022年)

https://doi.org/10.6342/NTU202201074

摘要

在即將到來的未來，穿戴式電子產業與半導體電子封裝技術將蓬勃發展，對於高頻信號傳輸逐步上升的需求，同時具備低介電常數與低消散因子的聚醯亞胺將成為令人充滿興趣的研究。在第2章中，我們全面性探討了化學結構與聚醯亞胺的介電性質之間的關聯性，多達35種含有如酯基、含氟基團與醚基的各種搭配的聚醯亞胺在透過高分子的加成反應與熱閉環步驟被成功合成出來，其化學結構、物理性質如機械性質與介電性質也通過系統性的探討，我們發現在過去所使用的根據各個基團的貢獻數值的數值相加方法，是無法與具備低介電常數 (Dk) 與消散因子 (Df) 的聚醯亞胺形成良好的關聯性，而且也無法用以分辨幾何異構物對於介電性質的影響。因此透過利用密度泛函理論模擬方法 (DFT)，以上提及的議題將成功被解答，我們發現聚醯亞胺的介電常數與消散因子與單位莫爾體積下的極化率與偶極-偶極矩有著強烈的關聯性，同時這些結果詮釋了高分子鏈與鏈之間排列關係與介電常數、以及高分子鏈本身的僵硬度對於消散因子的影響與效果；後續結合以實驗量測得到的密度，以及一個修正高分子僵硬度的因子，最終我們確立了一個能夠分別連結介電常數與消散因子和結構參數的關聯性的分析。根據的2章的發現，在的3章中我們提出多種實際聚醯亞胺單體的結構設計，以含二酯的TAHQ-ABHQ作為原型，我們設計了一系列ABHQ系列的二胺，包含環烷、間位、萘環、降冰片烷側基、聯苯側基、甲氧基、四氟與四甲基取代的苯中心，並探討他們對於莫爾自由體積的影響，藉由研究他們的熱與機械性質，我們找到一個合適的方法來維持高分子的僵硬度並同時降低介電常數：環烷中心可提供額外自由體積但會小幅減低僵硬度，四甲基取代也有同樣的效果、四氟取代達成了介電常數與消散因子的同時降低，而其餘具備高自由度與低級化率的高立障側基，也能提供額外自由體積。結合上述的實際合成設計以及的2章中的結構與介電模擬分析，本研究為具備低介電常數與消散因子的聚醯亞胺提供了一個虛實相應的準則，並能應用在逐步成長的通訊技術上。

關鍵字

聚醯亞胺 ； 高頻 ； 密度泛函理論模擬 ； 低介電常數 ； 低消散因子

並列摘要

In the upcoming future, the development of the wearable electronic devices and the technique of the semiconductor packaging are urging. Materials such as polyimides (PIs) possessing both low dielectric constant (Dk) and dissipation factor (Df) remain an intriguing study for the ever-increasing demand for the high frequency transmission of signals. In chapter 2, the relationship between the chemical structures and the dielectric properties of PIs were comprehensively investigated. 35 kinds of PIs with different types of functional groups such as ester, fluorine and ether were prepared via polyaddition and thermal imidization. Their chemical structures and physical properties including the mechanical and dielectric properties were systematically studied. We found that the additive group contribution method failed to provide an effective correlation on PIs with low Dk and Df values, and it is incapable of distinguishing geometry isomers of PIs. Herein, by utilizing the density function theory simulation (DFT), which is usually utilized to stimulate the local chemical structure of given formula, we successfully remedied those issues. Local chemical structures and the orientation were presented. The Dk and Df values of PIs provided strong correlations with volumetric polarizability and volumetric dipole moment. The results elaborated the effect of the interchain behavior to the Dk values and the impact of the chain rigidity on the Df values of PIs. Combining with the molar volume derived from the film density, and a correction factor expressing the polymer rigidity, we eventually established a confident correlation of Dk and Df values with the structure parameters of PIs, respectively. Based on the findings in chapter 2, chapter 3 provided attempts to design chemical structures of polyimide. By setting the THAQ-ABHQ, possessing a diester functional group, as the prototype, we synthesized 8 different ABHQ-based diamines, including aliphatic, meta-position and naphthalene core, norbornane, phenyl, methoxy, tetra-fluorine and methyl side chain and investigated their impact on the molar free volume. By studying their thermal and dielectric properties, we discovered a proper strategy to maintain the rigidity of the polymer and decrease the Dk values. An aliphatic core could provide extra molar free volume with a slight increase in the Df values while the tetra-substituted derivatives feature a both decrease in Dk and Df values. On the other hand, the bulky side groups with high degree of freedom or low polarizability also provide additional molar free volume without other side effects. Combining these concrete designs on functional groups of PIs and the structural-dielectric analysis based on DFT simulations, this study provides a guideline for bricks-and-clicks-like molecular design of PIs for the ever-increasing communications technology.

並列關鍵字

polyimide ； high frequency ； low dielectric constant ； ultra-low dissipation ； DFT simulations

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