Process development, repair and reliability study with Anisotropic Conductive Film bonding as a replacement for surface mount connectors and hotbar soldering

Flexible Printed Circuit (FPC) boards are being widely used for a number of applications to enable products in a three dimensional format thereby utilizing the “dead” space within the product envelop. During the past few years, the usage and complexity of FPC made of polyimide, polyester or teflon have grown substantially and are expected to continue to grow even more in the next coming years. In the past these FPC´s have been connected to other FPC´s or to a PCB with help of mainly connectors but the interest of replacing these connectors with a lower cost and smaller footprint connections with help of Anisotropic Conductive Film (ACF) is being widely explored. This paper will report the development of fine pitch ACF bonding down to 0,2mm and the mechanical and thermo-mechanical reliability of the ACF interconnects. The influence of difference process parameters and ACF materials on the ACF process yield will be discussed as well.