Scalable Roll-to-Roll Approach for Encapsulating Long-Length Flexible Printed Circuit Boards

The encapsulation process in flexible printed circuit board (FPCB) manufacturing typically involves laminating a flexible copper-clad laminate (FCCL) with a coverlay film, using heat and pressure in methods such as hot press lamination. However, when they are applied to long-length FPCBs for electric vehicle applications, traditional hot press methods face challenges in scalability and productivity. To overcome these challenges, this study proposes a scalable roll-to-roll approach for encapsulating long-length FPCB. This approach enhances scalability to meet the requirement of long-lengthening continuously, but this can lead to incomplete filling in narrow circuit patterns due to insufficient flowability of the B-stage adhesive. To enhance flowability, a roll-to-roll system was developed, incorporating a rubber roll and a steel roll for the adhesive material. The effectiveness of copper width dimensions and process parameters on encapsulation performance was investigated in the experimental analysis according to the rheological and thermomechanical characterizations of the B-stage adhesive. These results were quantified through image analysis and visualized using contour mapping to exhibit the influence of process parameters on the filling area. The reliability and durability of the developed approach were validated through the analysis of adhesive properties and electrical performance. The developed roll-to-roll approach to the encapsulation process enables scalability while ensuring the durability and reliability of the long-length FPCB.