Multi-layered interconnect structure using liquid crystalline polymer dielectric

Abstract

A multi-layered interconnect structure and method of formation. In a first embodiment, first and second liquid crystal polymer (LCP) dielectric layers are directly bonded, respectively, to first and second opposing surface of a thermally conductive layer, with no extrinsic adhesive material bonding the thermally conductive layer with either the first or second LCP dielectric layer. In a second embodiment, first and second 2S1P substructures are directly bonded, respectively, to first and second opposing surfaces of a LCP dielectric joining layer, with no extrinsic adhesive material bonding the LCP dielectric joining layer with either the first or second 2S1P substructures.

1 . A method for forming an electrical structure, comprising:
 providing a first 2S1P substructure, said first 2S1P substructure comprising a first dielectric layer, a first power plane within the first dielectric layer, a top signal plane on a top surface of the first dielectric layer, a bottom signal plane on a bottom surface of the first dielectric layer, and a first electrically conductive via;   providing a second 2S1P substructure, said second 2S1P substructure comprising a second dielectric layer, a second power plane within the second dielectric layer, a top signal plane on a top surface of the second dielectric layer, a bottom signal plane on a bottom surface of the second dielectric layer, and a second electrically conductive via;   providing a joining layer, said joining layer having first and second opposing surfaces and an electrically conductive plug therethrough, wherein the joining layer comprises a liquid crystal polymer (LCP) dielectric material; and   directly bonding the joining layer to the first dielectric layer of the first 2S1P substructure at the first opposing surface and to the second dielectric layer of the second 2S1P substructure at the second opposing surface, by subjecting the first 2S1P substructure, the joining layer, and the second 2S1P substructure to an elevated temperature, elevated pressure, and dwell time sufficient for effectuating said bonding, wherein the elevated temperature is less than the nematic-to-isotropic temperature of the LCP dielectric material during the dwell time, wherein no extrinsic adhesive material is disposed between the joining layer and the first dielectric layer, wherein no extrinsic adhesive material is disposed between the joining layer and the second dielectric layer, and wherein the electrically conductive plug electrically couples the first electrically conductive via to the second electrically conductive via.   
   
   
       2 . The method of  claim 1 , wherein the polymer chain structure and associated directional orientation of the LCP dielectric material of the joiner layer remains essentially unchanged throughout the dwell time. 
   
   
       3 . The method of  claim 1 , wherein the coefficient of thermal expansion (CTE) of the LCP dielectric material of the joiner layer remains essentially unchanged throughout the dwell time. 
   
   
       4 . The method of  claim 1 , wherein the elevated pressure is in a range of about 1000 psi to about 3000 psi. 
   
   
       5 . The method of  claim 4 , wherein the dwell time is at least about 2 minutes. 
   
   
       6 . The method of  claim 4 , wherein the first electrically conductive via comprises a first plated through hole that electrically couples the top and bottom signal planes of the first 2S1P substructure, and wherein the second electrically conductive via comprises a second plated through hole that electrically couples the top and bottom signal planes of the second 2S1P substructure. 
   
   
       7 . The method of  claim 1 , wherein the first electrically conductive via comprises a first plated blind via that electrically couples the first power plane to the bottom signal plane of the first 2S1P substructure, and wherein the second electrically conductive via comprises a second plated blind via that electrically couples the second power plane to the top signal plane of the second 2S1P substructure. 
   
   
       8 . The method of  claim 1 , wherein the first electrically conductive via comprises a plated blind via that electrically couples the first power plane to the bottom signal plane of the first 2S1P substructure, and wherein the second electrically conductive via comprises a plated through hole that electrically couples the top and bottom signal planes of the second 2S1P substructure.