Method and apparatus for mounting and cooling a circuit component

Abstract

A circuit sub-assembly is disclosed adapted for mounting and cooling a circuit component having a plurality of contacts. Circuit component can be mounted on a rigid substrate of a thermally conductive material having electrically insulating regions with a circuit board arranged between the circuit component and the substrate. The circuit board, which carries conductive traces that terminate in contact pads, is secured to the substrate with at least some of the contact pads on the circuit board disposed on the side of the board facing the substrate, some of the latter contact pads being bonded to the substrate. To establish both an electrical and a thermal connection between the contacts of the circuit component and the contact pads bonded to the substrate, there are blind holes formed in the base of the circuit board, each hole terminating at a respective one of the contact pads bonded to the substrate.

Please amend the claims in accordance with the following listing: 
     
         1 . A circuit sub-assembly comprising:
 a) a rigid substrate formed of a thermally conductive material, the substrate having a face with at least one electrically isolating region thereupon; and   b) a circuit board having an electrically insulating base, a first side coupled to the rigid substrate and a second side opposing the first side, the circuit board having a plurality of traces terminating in respective contact pads, at least some of the contact pads arranged on the first side of the circuit board being bonded to the electrically isolating region of the rigid substrate, the circuit board having a plurality of holes formed therein, the holes being filled with electrically and thermally conductive material or material combination, at least some of the holes in the base of the circuit board terminating at, but not passing through, respective contact pads bonded to the electrically isolating region of the rigid substrate, the electrically and thermally conductive material or material combination being in contact with a respective contact pad, thereby forming a respective via.   
     
     
         2 . A circuit sub-assembly as claimed in  claim 1 , further comprising a circuit component mounted on the second side of the circuit board and electrically connected to the contact pads of the circuit board by respective vias. 
     
     
         3 . A circuit sub-assembly as claimed in  claim 2 , wherein the rigid substrate or the electrically isolating region thereof further comprises a substrate contact pad substantially aligned with a respective contact of the circuit component. 
     
     
         4 . A circuit sub-assembly as claimed in  claim 3 , wherein all electrical connections between the traces of the circuit board and the contacts of the circuit component are further connected to substrate pads. 
     
     
         5 . A circuit sub-assembly as claimed in  claim 1 , wherein the base of the circuit board is flexible. 
     
     
         6 . A circuit sub-assembly as claimed in  claim 1 , wherein the base of the circuit board is rigid. 
     
     
         7 . A circuit sub-assembly as claimed in  claim 1 , wherein the base of the circuit board has a thickness in the range of 1 μm to 125 μm. 
     
     
         8 . A circuit sub-assembly as claimed in  claim 1 , wherein the vias are formed of two or more layers. 
     
     
         9 . A circuit sub-assembly as claimed in  claim 1 , wherein the base of the circuit board is flexible and is made of one or more plastics materials. 
     
     
         10 . A circuit sub-assembly as claimed in  claim 1 , wherein the rigid substrate has a thickness in the range of 5 μm to 250 μm. 
     
     
         11 . A circuit sub-assembly as claimed in  claim 1 , wherein the rigid substrate is devoid of conductive traces. 
     
     
         12 . A circuit sub-assembly as claimed in  claim 1 , wherein the electrically and thermally conductive material or material combination filling the holes comprises at least one metallic material. 
     
     
         13 . A circuit sub-assembly as claimed in  claim 12 , wherein the at least one metallic material filling the holes is plated therein. 
     
     
         14 . A circuit sub-assembly as claimed in  claim 12 , wherein each via filling a hole in the base of the circuit board is formed as a plating of the side of the respective contact pad facing away from the rigid substrate that is soldered to a respective contact of the circuit component. 
     
     
         15 . A circuit sub-assembly as claimed in  claim 2 , wherein a single solder joint is present between a contact of the circuit component and a respective via. 
     
     
         16 . A circuit sub-assembly as claimed in  claim 2 , wherein the circuit component comprises an array including a plurality of vertical-cavity surface-emitting lasers (VCSELs). 
     
     
         17 . A circuit sub-assembly as claimed in  claim 2 , wherein the circuit component is a microprocessor chip. 
     
     
         18 . A circuit sub-assembly as claimed in  claim 1 , wherein the contact pads are present in an amount of more than 50 contacts/mm 2 . 
     
     
         19 . A circuit sub-assembly as claimed in  claim 1 , wherein a pitch between adjacent contact pads and/or adjacent holes is equal to or less than 200 μm. 
     
     
         20 . A circuit sub-assembly as claimed in  claim 19 , wherein the pitch between adjacent contact pads and/or adjacent holes is equal to 50 μm or more.