含嘧啶聚酰亚胺的制备及其粘结性能

Synthesis and Adhesion Properties of Polyimdies Containing Diphenylpyrimidine

综合2,5-二氨苯基嘧啶(PRM)的刚性结构特征和配位化学特征以及二苯醚二胺(ODA)的柔性结构特征,制备出一系列性能可控的含嘧啶聚酰亚胺.含嘧啶聚酰亚胺的玻璃化转变温度、热稳定性、拉伸强度和模量等,均随聚酰亚胺中PRM比例的升高而增加.但热膨胀系数却随PRM比例的增加而降低,当PRM和ODA的比例为1∶1时,热膨胀系数为17×10-6K-1,与铜箔的热膨胀系数一致,可与铜箔形成尺寸稳定的无胶挠性覆铜板;同时,这一比例的含嘧啶聚酰亚胺与铜箔的粘结强度也达到最高(17.3 N·cm-1).这种含嘧啶聚酰亚胺的性能可以满足无胶挠性印制电路对基底膜材料的尺寸稳定性和粘结性能的要求.

A series of novel polyimide（ PI） copolymers with tailored properties were synthesized via the poly-（ amic acid） s（ PAAs） from the reaction of 3,3＇,4,4＇-biphenyl tetracarboxylic dianhydride with 4,4-oxydianiline（ ODA） and 2,5-bis（ 4-aminophenyl） pyrimidine（ PRM）. PRM has an extended conjugated rigid rodlike structure containing the pyrimidine group. The effects of the content of PRM on thermal and mechanical properties of the copolymers were investigated. Their glass transition temperatures and the temperatures of 5%weight loss were evidently improved with increase of the molar ratio of PRM to ODA. The tensile strength and modulus of the copolymer films were increased in accordance with the order of the rigidity of the polymer backbones. The value of the coefficient of thermal expansion（ CTE） gradually decreased as the PRM content increased. At a molar ratio of PRM to ODA of 1∶ 1,the CTE values of the PI was 17 × 10- 6K- 1,which was the same value as that of the copper foil. The two-layer flexible copper-clad laminates（ FCCLs） were prepared by coating these PAAs solutions onto copper foils and then imidizing thermally. The adhesion strength of polyimide / copper laminate showed peaky curve with the increase of PRM content. While a molar ratio of PRM to ODA at 1∶ 1,the 90°-peel strength of the laminate reached a maximum value of 17. 3 N·cm- 1. The flexible structure of ODA and the chemical nature of PRM lead to two-layer FCCL with high adhesion strength as well as thermal-dimensional stability. Furthermore,scanning electron microscope was employed to determine the fracture surface morphology of PI / copper joints.