The use of traditional photosensitive polyimide (PSPI) insulating materials, which possess high coefficients of thermal expansion (CTE) and poor adhesion to copper, easily causes failure issues in the redistribution layers (RDLs). However, there are some trade-offs in the design of the low-CTE PSPI materials such as the ultraviolet (UV) transmittance of the precursors and the dielectric properties of the films. To overcome the above challenges, an AB2-type fluorinated monoamine (ETFPh-NH2) with a nonplanar steric structure was designed and synthesized, which was then used as an end-capper attached to poly(amic ester) (PAE) with a linear/stiff structure. The PSPI solutions were then developed by using the as-prepared PAE resins, solvents, and other additives. Despite the presence of ETFPh-NH2 with a relatively low molar ratio to the total precursor chains, the transparency of the PAE-4 was notably enhanced, resulting in the achievement of the high-resolution lithographic pattern. Meanwhile, the PI-4 film exhibited low-CTE characteristics (23.65 ppm K–1), and its mechanical and low dielectric properties were enhanced by the microbranched cross-link structure, which was constructed by the reaction of the arylethynyl groups during the imidization process. Furthermore, the adhesion between the PI films and Cu was significantly improved by introducing the aromatic silane (TMS). In short, PI-4, which exhibited high-dimensional stability, strong adhesion with Cu, and photopatternable capabilities, could be a feasible and reliable material for use in advanced packaging. In addition, the developed end-groups modification strategy seems to be an effective way to greatly improve the overall performance of PSPI materials.
Zhenjie Zheng,Jingxuan Wang,Mengqi Ma,Yunpeng Xu,Da Huang,Jian Wang,Cuiying Lin,Zhenyu Lin,Fang Luo
Sensitive and selective detection of N -nitrosodimethylamine (NDMA), a highly carcinogenic environmental contaminant, is essential for public health and safety. In this study, we have developed a homogeneous electrochemiluminescence (ECL) biosensor for ultrasensitive NDMA detection by integrating Nafion-functionalized covalent organic framework (COF) with aptamer recognition and magnetic separation. The imine-linked COF (COF-LZU1) scaffold not only enables stable encapsulation of Ru(bpy) 3 2 + , but also creates a confined microporous environment that locally concentrates c (TPrA) and enhances the generation and survival of TPrA radicals, thereby amplifying the ECL signal. Nafion further improves Ru loading and ionic conductivity. Biotinylated aptamers were initially immobilized on streptavidin-coated magnetic beads (MBs) and hybridized with complementary DNA-modified Ru@COF-LZU1 to form Ru@COF-LZU1-MBs complex. Upon NDMA binding, a conformational switch releases Ru@COF-LZU1 into the solution. After magnetic separation, the ECL signal of the supernatant is measured in the presence of TPrA. This homogeneous format avoids electrode surface modification, which is commonly required in conventional Ru@COF-LZU1-based ECL sensors, offering improved reproducibility and simplified operation. The biosensor exhibits a wide linear range (100 fg/mL - 100 ng/mL) with a low detection limit of 9.11 fg/mL. This platform offers a sensitive, reproducible, and facile strategy for monitoring NDMA and similar small-molecule contaminants in complex matrices.
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