Layer to layer interconnect

Abstract

The present invention includes stack flexible circuit layers having raised features or bumps for Z-axis interconnection to another circuit layer or electrical component. An intermediate or adhesive layer separates each circuit layer. The multiple layers are stacked with the raised features from one layer aligning with pads of an overlying or underlying layer and are laminated so that the raised features pierce the intermediate or adhesive layer and make electrical contact with the corresponding pad of the adjacent circuit layer. The raised features may have a shape sufficient to penetrate the intermediate and/or the adhesive layer allowing blind vias to be made without pre-drilling the intermediate or adhesive layers. The intermediate layer of film can have a function other than or in addition to that of an adhesive. For example, in a connector application where the raised feature is used to make contact to corresponding pads, a film that has a low permeability to water could be placed between the raised features and corresponding pads on the next layer. The low water permeability film would act as a sealant to prevent environmental attack on the connection. The raised feature would penetrate the sealant to make electrical contact to a corresponding pad. This would allow the connector to be disassembled and reconnected.