RLC effects in fine pitch anisotropic conductive film connections

The resistance, capacitance and inductance of Anisotropic Conductive Film (ACF) connections determine their high frequency electrical characteristics. The presence of capacitance and inductance in the ACF joint contributes to time delays and crosstalk noise as well as simultaneous switching noise (SSN) within the circuit. The purpose of this paper is to establish an experimental method for estimating the capacitance and inductance of a typical ACF connection. This can help to provide a more detailed understanding of the high frequency performance of ACF assemblies. Design/methodology/approach Experiments on the transient response of an ACF joint were performed using a digital oscilloscope capable of achieving the required ns resolution. An equivalent circuit model is proposed in order to quantify the capacitance (C) and inductance (L) of a typical ACF connection and this model is fitted to the experimental data. The equivalent model consisted of two resistors, an inductor, and a capacitor. Findings The capacitance and inductance of a typical ACF connection were estimated from the measured transient response using Kirchhoff's Voltage Law. The method for estimation of R, L, and C from the transient response is discussed, as are the RLC effects on the high frequency electrical characteristics of the ACF connection. Research limitations/implications There was decay time deviation between the calculation and the experiment. It may be resulted from the skin effect in the high frequency response and the adhesive surrounding joint as well. The main reason may be the capacitance dielectric lost. Further research work will be done to test the dielectric lost in the ACA joint. What is original/value of paper This paper presents a new method to characterise the high frequency properties of ACA interconnections and will be of use to engineers evaluating the performance of ACF materials in high frequency applications.