Optimum Design of Flexible Printed Circuit Boards with Respect to Flexural Strength

In the course of flexible PCB manufacture where the reliability of those parts subjected to bending stresses is a matter of utmost concern, the design of the PCB should enable the flexible interconnection parts to withstand the greatest possible bending stresses. Therefore, extensive investigations were carried out to demonstrate the relationship between the design and flexural strength. The study shows the functional correlation between bending radius, material thickness, type of material, design of the circuit and number of bending cycles. Only with a detailed knowledge of these five mentioned properties can reliable PCBs be designed and manufactured. The results of these investigations are based on a great number of bending experiments performed on a practical basis and demonstrate the numerical relation between all effects. As bending cycle results are subject to relatively high deviations, the whole problem has been investigated by means of statistical evaluation criteria.