Flexible Pcb Fatigue Reliability Analysis

In recent years, the application of Flexible Printed Circuit (FPC) is increasing dramatically due to massive users of mobile phones and other electronic products in our country. FPC generally is constructed with good bending properties of the copper layer, play a supportive role of the polyimide substrate, whose adhesive layer has high peel strength, good adhesion, high reliability and other benefits. Because it's flexible, FPC is easily and widely used in various electronic packages, such as mobile phones, laptop, display device, touch control board and Integrated Circuit package. In most of these applications, failure of FPC can directly lead to failure of device, even serious pecuniary loss. Currently the reliability of mechanical fatigue has been a hot topic in the reliability research filed. However, reliability data on FPC is not commonly available in published literature. Especially, the fatigue property and analysis of FPC are far from being widely launched, this research field is a blank to be filled.This paper relied on the project: Reliability of Flexible Materials which is supported by Nokia Beijing Research Center. It focuses on theoretical, experimental and finite element simulation to study fatigue reliability of FPC. First of all, we introduce some of the major theories and methods on fatigue reliability, such as reliability index, the estimation of population parameters on fatigue properties test, Stress-Strength interference model, Miner linear cumulative damage theory, Manson-Coffin low-cycle fatigue equation.At the macroscopic level, we introduce the relevant technical standards, failure criterion. The fatigue tests are carried out, several important issues are discussed. The FPC fatigue test is systematically described. The test object, purpose, and equipments are proposed and the test data are processed. Refer to Standard GB/T 1449-2005 and IPC-TM-650, we made a detailed feasible plan of the FPC fatigue test program.Finally, from the perspective of finite element analysis, with the use of GUI and command stream, we construct a detailed model of the FPC on ANSYS, and the fatigue property of FPC is analyzed. After applied static load and other constraints, we can see the different node's displacement and stress trend. Cumulative Fatigue Usage is to evaluate the performance of the important parameters of fatigue life on ANSYS. We mainly consider three factors which would affect the value of Cumulative Fatigue Usage, including pressure, force area size and meshing size.We also use LS-DYNA to create a detailed model of the FPC, and calculate the fatigue properties of FPC by loading the sine function. We considered four combinations with two different loads and two pressure areas. From the results, we can study the effect, which is caused by load equation, mode of loading and load frequency, on the fatigue properties by comparing the maximum and minimum Von Mises Stress.