热塑型聚酰亚胺的制备及其粘接性能研究

Preparation and bonding property of thermoplastic polyimide

为了改善两层型挠性覆铜板(2L-FCCL)中热塑型聚酰亚胺(TPI)对热固型聚酰亚胺(PI)薄膜和铜箔的粘接性,本文选用具有柔性结构的芳香二酐单体和芳香或脂环的二异氰酸酯单体通过一步反应制备得到TPI样品,然后将其直接涂覆在表面经过预处理的商品化热固型PI薄膜上得到复合膜,最后经过高温热压得到相应的2L-FCCL。通过观察所得TPI反应液的状态并进行DSC测试,选定了有机溶剂可溶且Tg为226.5℃的TPI-8;然后通过TGA、TMA和拉伸试验测得TPI-8的2%热分解温度(T2%)为464℃、50~200℃的热膨胀系数(CTE)为64.25×10^(-6)℃^(-1)、拉伸强度为64.52MPa、弹性模量为1.75 GPa、断裂伸长率为62%,并通过FTIR对其化学结构进行了确认;最后分别研究了两种热固型PI薄膜的碱水预处理时间对所得FCCL粘接性能的影响,发现其中SPI膜经60℃碱水处理1 min和3 min后得到的FCCL90°剥离强度(90°PS)≥0.7 N/mm且最大值达到0.94 N/mm,而UPI膜经同样热碱水处理1~7 min后得到的FCCL 90°PS均≤0.6 N/mm。因此,采用本方法可一步快速简单的制备可溶解且热学性能、力学性能、尺寸稳定性较好的TPI,同时其对铜箔以及表面经过碱水预处理的SPI具有较好的粘接性能,满足FCCL相关标准的要求。

In order to improve the adhesion of thermoplastic polyimide(TPI)between thermosetting polyimide(PI)film and copper foil in two-layer flexible copper clad plate(2L-FCCL),a series of TPI samples were prepared by one-step reaction using flexible aromatic dianhydride monomers and aromatic or alicyclic diisocyanate monomers.Then,the selected TPI solution was directly coated on the pretreated commercial thermosetting PI film to obtain the composite film,and the corresponding 2L-FCCL was obtained by hot pressing at high temperature.By observing the state of the TPI reaction solution and conducting DSC testing,TPI-8 is selected,which is soluble in organic solvent and has a Tg of 226.5℃.Then,TGA,TMA,and tensile tests show that the 2%thermal decomposition temperature(T2%)of TPI-8 is 464℃,the thermal expansion coefficient(CTE)of 50-200℃is 64.25×10^(-6)℃^(-1),the tensile strength is 64.52 MPa,the elastic modulus is 1.75 GPa,and the elongation at break is 62%,and its chemical structure is confirmed by FTIR.Finally,the effect of alkaline pretreatment time of two kinds of thermosetting PI films on the bonding properties of resulting FCCLs was studied.It is found that the 90°peel strength(90°PS)of FCCLs are over 0.7 N/mm and the maximum value is 0.94 N/mm after SPI films treated with alkaline water at 60℃for 1 min and 3 min.However,the 90°PS of FCCLs obtained by UPI films treated with the same hot alkaline water for 1-7 min are all less than 0.6 N/mm.Therefore,this method can be used to quickly and simply prepare TPI by one step,which is soluble and has good thermal,mechanical properties and dimensional stability.Meanwhile,it has good bonding properties for copper foil and SPI that the surface was pretreated with alkali water,and meets the requirements of relevant FCCL standards.