Flex-rigid wiring board

A flex-rigid wiring board comprising:

• a flexible substrate comprising a flexible base material, a plurality of first interconnecting pads located at an end of the flexible substrate and a plurality of first conductor layers respectively connected to the first interconnecting pads and extending to an opposite end of the flexible substrate;
• a rigid substrate disposed adjacent to the flexible substrate and comprising a rigid base material, a frame pattern provided on an end of the rigid substrate and surrounding a plurality of second interconnecting pads a plurality of via-contacts respectively provided in said second interconnecting pads and a plurality of second conductor layers connected to respective via-contacts;
• a coverlay provided between the first conductor layers and the frame pattern to electrically insulate the frame pattern from the first conductor layers;
• and
• an anisotropic conductive adhesive layer provided between the first and second interconnecting pads within the frame pattern to form a compression connection between the first and second interconnecting pads.

A flexible substrate comprising a flexible base material and a plurality of first conductor layers and first interconnecting pads;

• a rigid substrate comprising:
• a first rigid-substrate layer having a cut formed at an end thereof, and
• a second rigid-substrate layer disposed under the first rigid-substrate layer and including;
• a frame pattern formed to be exposed through the cut in the first rigid-substrate layer,
• a plurality of second interconnecting pads formed in an area surrounded by the frame pattern,
• a plurality of via-contacts formed beneath the second interconnecting pads, respectively, and
• a second conductor layer connected to each of the via-contacts;
• a coverlay provided between the first conductor layers and the frame pattern to electrically insulate the frame pattern from the first conductor layers;
• and
• an anisotropic conductive adhesive layer provided between the first and second interconnecting pads within the frame pattern to provide a compression connection between the first and second interconnecting pads.

A method of producing a flex-rigid wiring board in which a rigid substrate formed from a stack of rigid base materials and a flexible substrate formed from a flexible base material are joined to each other, the method comprising the steps of:

• preparing a flexible substrate including a plurality of first interconnecting pads and a plurality of first conductor layers connected to the first interconnecting pads, respectively;
• preparing a first rigid-substrate layer having a cut formed at either end thereof while preparing a second rigid-substrate layer including a frame pattern exposed from the cuts, a plurality of second interconnecting pads formed in an area surrounded by the frame pattern, a plurality of via-contacts formed beneath the second interconnecting pads, respectively, and a second conductor layer connected to each of the via-contacts;
• stacking the first and second rigid-substrate layers together to form a rigid substrate;
• forming a coverlay between the first conductor layers of the flexible substrate and the frame pattern of the second rigid-substrate layer to electrically insulate the frame pattern from the first conductor layers;
• forming an anisotropic conductive adhesive layer between the first interconnecting pads of the flexible substrate and second interconnecting pads of the rigid substrate;
• and
• fitting the free end of the flexible substrate into the cut in the rigid substrate to provide a compression connection between the first and second interconnecting pads via the anisotropic conductive adhesive layer.