基于LCP基板的平面叉指电容研究

Research on planar interdigital capacitance based on LCP substrate

平面叉指电容作为电路系统中的重要器件,对电路性能影响极其重要。本文在50μm厚度双面覆铜的液晶聚合物(Liquid Crystal Polymer,LCP)基板上加工了多款平面叉指电容,系统研究了平面叉指电容的叉指长度、宽度和间距的变化对其电容值的影响规律。结果表明:叉指长度从3 mm增加到4 mm,叉指电容容值增加1.63 pF;叉指宽度从0.2 mm增加到0.3 mm,叉指电容容值增加2.35 pF;叉指间距从0.1 mm增加到0.2 mm,叉指电容容值减少0.75 pF。通过集总参数等效,建立了平面叉指电容的等效电路,分析了等效电路中集总器件和不同平面叉指电容物理结构参数的对应关系,为LCP工艺中电容的设计提供了技术参考。

The planar interdigital capacitor plays an important role in the performance of the circuits. A variety of planar interdigital capacitors were fabricated on double-sided copper liquid crystal polymer ( LCP) substrate with the thickness of 50 μm, and the influence of interdigital fingers length, width and spacing on the capacitance value was determined. The results show that when the length of interdigital increases from 3 mm to 4 mm, the capacitance of interdigital increases by 1. 63 pF;When the width of interdigital increases from 0. 2 mm to 0. 3 mm, the capacitance of interdigital increases by 2. 35 pF;And when the spacing of interdigital increases from 0. 1 mm to 0. 2 mm, the capacitance of interdigital decreases by 0. 75 pF. The equivalent circuit of the planar interdigital capacitor was established by the lumped parameter equivalent. The correspondence between the lumped device and the physical structure parameters of different plane interdigital capacitors in the equivalent circuit was analyzed, which provides the technical reference for the design of the capacitor in the LCP process.