Rediscovering Multilayer Rigid-Flex with Z-interconnect Technology

Rigid-flex allows designers to replace multiple substrates interconnected with connectors, wires, and ribbon cables with a single package offering improved performance, reliability, and a potential cost-effective solution. However, processing and materials selection is critical in order to achieve high quality multilayer, rigid-flex structures. To date, there is no technology available which can economically produce high density multilayer rigid-flex with rigid or flex originating from any layer in the stack. In the present study, a novel strategy allowing for multi-layer rigid flex structures is reported. Specifically, metal-to-metal z-axis electrical interconnection among the flexible and rigid elements during lamination to form a single package rigid-flex structure is described. Conductive joints are formed during lamination using an electrically conductive adhesive (ECA). As a result, structures can be fabricated with multiple flexible elements at any arbitrary layer. Recent development work on flex j...