Solution for removing thermal grease from electronic cards

Abstract

A water-free solution and method for dissolving and removing thermal grease from a high frequency logic device (e.g. a microprocessor in the form of a BGA and ASIC in the form of Quad Flat Pack component) assembled onto an electronic card which needs to be reworked. The method and solution of the present invention allow the complete removal of the grease by a simple and fast process, using an alcoholic, inert and cheap solution, without needing a mechanical action (e.g. brushing) and without damaging the card components. Furthermore, given the low surface tension of the alcoholic solution a good diffusion within the small holes and spaces of the card is ensured.

What is claimed is:  
     
         1 . A substantially water free solution for dissolving thermal grease comprising an alcohol and at least one compound selected from the family of neutral ammonium salts of organic acids.  
     
     
         2 . The solution of    claim 1    wherein the at least one compound selected from the family of neutral ammonium salts of organic acids is ammonium acetate.  
     
     
         3 . The solution of    claim 2    wherein the alcohol is isopropanol.  
     
     
         4 . The solution of    claim 2    wherein the concentration of the ammonium acetate is in the range 4 g/l and 16 g/l.  
     
     
         5 . The solution of    claim 4    wherein the concentration of ammonium acetate is 14 g/l.  
     
     
         6 . A method for removing thermal grease from an electronic card, the electronic card having plated via holes and including electronic components, the method including the step of immersing the card in the solution of    claim 1   .  
     
     
         7 . A method for reworking an electronic card wherein the card is cleaned using the method of    claim 7   .