Thermally conductive interface

Abstract

A thermally conductive material is provided as a mixture of a silicone, a ceramic powder, and a curing catalyst. The material may be pre-formed into a pad and each side of the film protected with removable release layers. Each side of the film may also include a coating of an adhesive material that aids in coupling the interface film with a surface. The material may alternatively be produced in a screen-printable paste. As such, a layer of the paste may be screen-printed on a surface as complete sheet form or as a patterned film by using a stencil patterned screen mesh. The interface material is sandwiched between a printed circuit board and a heat sink to form the circuit board assembly. In a multi-step press process, the assembly is cured and a laminate formed. The assembly process may also include a priming function that prepares metal surfaces of the circuit board and heat sink for receiving the interface material.

1 . A method of manufacturing a circuit board assembly having improved heat dissipation functionality comprising: 
 providing a thermally conductive, electrically non-conducting interface film including: a first side and a second side wherein the interface includes resilient silicone, a ceramic powder for enhancing thermal conductivity, an organic curing catalyst, a first release layer protecting a first side, and a second release layer protecting a second side;    sandwiching the interface between a metal base layer of a printable circuit board and a planar side of a heat sink to form the assembly;    in a mechanism for applying pressure, applying a first pressure treatment to the assembly at a room temperature to increase surface contact and to remove air pockets;    applying a second pressure treatment to the assembly at a high temperature to cure the interface and create a laminate; and    applying a third pressure treatment to the assembly at a low temperature to controllably return the assembly to room temperature.    
   
   
       2 . The method of  claim 1 , wherein the resilient silicone is a dimethyl silicone.  
   
   
       3 . The method of  claim 1 , wherein the ceramic powder includes a ceramic selected from the group consisting of aluminum oxide; aluminum nitride; and boron nitride.  
   
   
       4 . The method of  claim 1 , wherein the interface film further includes: 
 a first adhesive applied to the first side; and    a second adhesive applied to the second side.    
   
   
       5 . The method of  claim 1 , wherein the second pressure treatment includes application of at pressure of at least 140 psi at a temperature of at least 320 degrees Fahrenheit for at least 20 minutes.  
   
   
       6 . The method of  claim 1 , further comprising: trimming excess interface material from an edge of the assembly.  
   
   
       7 . The method of  claim 1 , wherein the interface film has a pre-laminate thickness of between 2 and 200 mils.  
   
   
       8 . The method of  claim 1 , wherein the interface film has a pre-laminate thickness of approximately 4 mils.  
   
   
       9 . A method of manufacturing a circuit board assembly having improved heat dissipation functionality comprising: 
 screen-printing a thermally conductive, electrically non-conductive interface layer onto a first planar surface of one of a printable circuit board and a heat sink, wherein the interface layer comprises a mixture of dimethyl silicone, a ceramic powder for enhancing thermal conductivity, and a curing catalyst;    sandwiching the interface layer between a the first planar surface and a second planar surface of the remaining one of the printable circuit board and the heat sink to form the assembly;    applying a first pressure treatment to the assembly at a room temperature to increase surface contact and to remove air pockets;    applying a second pressure treatment to the assembly at a high temperature to cure the interface and create a laminate; and    applying a third pressure treatment to the assembly at a low temperature to controllably return the assembly to room temperature.    
   
   
       10 . The method of  claim 9 , wherein the second pressure treatment includes application of at pressure of at least 140 psi at a temperature of at least 320 degrees Fahrenheit for at least 20 minutes.  
   
   
       11 . The method of  claim 9 , wherein the third pressure treatment includes application of at pressure of approximately 40 for at approximately 10 minutes.  
   
   
       12 . The method of  claim 9 , wherein the second pressure treatment includes application of at pressure of approximately 150 psi at a temperature of at approximately 330 degrees Fahrenheit for at approximately 20 minutes.  
   
   
       13 . The method of  claim 9 , prior to screen-printing the interface layer, cleaning, surface roughening and applying a primer to the planar surface of the printable circuit board.  
   
   
       14 . The method of  claim 9 , by which film is applied in a continuous form or as a stencil patterned format, further comprising: repeating the screen-printing function a predetermined number of times to achieve a desired interface thickness.  
   
   
       15 . The method of  claim 9 , wherein the organic curing catalyst is a peroxide.  
   
   
       16 . The method of  claim 9 , wherein the ceramic powder includes a ceramic selected from the group consisting of aluminum oxide; aluminum nitride; and boron nitride.  
   
   
       17 . The method of  claim 9 , further comprising: trimming excess interface material from an edge of the assembly.  
   
   
       18 . The method of  claim 8 , wherein the dimethyl silicone is a methyl-poly silicone oxide.  
   
   
       19 . A thermally conductive interface for interposing between an aluminum heat sink and a copper base of an electronic device comprising: 
 a dielectric including a mixture of a methyl-poly silicone oxide, a ceramic powder for enhancing thermal conductivity; and a peroxide curing catalyst, wherein the dielectric is specially formulated to serve as a thermally conductive electric insulator;    a first adhesive applied to a first side of the interface, the first adhesive being configured to adhere to the aluminum heat sink;    a second adhesive applied to a second side of the interface, the second adhesive configured to adhere to the metal base;    a first release layer protecting the first side; and    a second release layer protecting the second side.    
   
   
       20 . The interface of  claim 19 , wherein the interface includes a thermal conductivity of approximately 0.37 W/m-k.