Method and apparatus for attaching solder members to a substrate

Abstract

The invention discloses a method for attaching solder members ( 114 ) to a substrate ( 112 ). The method includes forming a decal ( 110 ) with a plurality of solder members ( 114 ). The method further comprises aligning the decal ( 110 ) with the substrate ( 112 ) and transferring the solder members ( 114 ) on the decal ( 110 ) to the substrate ( 112 ).

What is claimed is:  
     
         1 . A method for attaching solder members to a substrate comprising the steps of: 
 forming a decal comprising a plurality of solder members;    aligning the decal with a first substrate; and    transferring the plurality of solder members on the decal to the first substrate.    
     
     
         2 . The method of  claim 1  wherein the step of aligning the decal with the first substrate further comprises bringing the plurality of solder members into contact with a portion of the first substrate.  
     
     
         3 . The method of  claim 1  wherein the step of transferring the solder members comprises heating the solder members.  
     
     
         4 . The method of  claim 1  wherein the step of transferring the solder balls comprises a solder reflow process.  
     
     
         5 . The method of  claim 1  wherein the step of forming a decal comprises arranging the solder members in a pattern corresponding to a pattern of contact pads formed on the first substrate.  
     
     
         6 . The method of  claim 1  wherein the step of forming a decal further comprises forming a plurality of apertures in a second substrate.  
     
     
         7 . The method of  claim 6  wherein the step of forming a decal further comprises affixing an adhesive film to the second substrate.  
     
     
         8 . The method of  claim 1  wherein the step of forming a decal further comprises forming indentations in second substrate.  
     
     
         9 . The method of  claim 1  wherein the step of forming a decal further comprises placing a plurality of solder members on a plurality of portions of an adhesive film.  
     
     
         10 . The method of  claim 7  and further comprising applying a light source to the adhesive film.  
     
     
         11 . The method of  claim 1  wherein the first substrate comprises a flip-chip electronic package.  
     
     
         12 . The method of  claim 1  wherein the first substrate comprises a ball grid array.  
     
     
         13 . The method of  claim 1 , wherein the plurality of solder members comprises a plurality of solder columns.  
     
     
         14 . The method of  claim 1 , wherein the plurality of solder members comprises a plurality of solder balls.  
     
     
         15 . The method of  claim 1 , wherein the step of transferring a plurality of solder members comprises a plurality of solder reflow processes.  
     
     
         16 . The method of  claim 4 , wherein the solder reflow process is performed in a nitrogen environment.  
     
     
         17 . A method for forming a decal for transferring solder members to a substrate comprising the steps of: 
 forming a plurality of apertures in a first substrate;    placing a plurality of solder members on the first substrate; and    allowing the plurality of solder members on the first substrate to enter the plurality of apertures to form a decal having a plurality of solder members.    
     
     
         18 . The method of  claim 17  wherein the step of allowing the plurality of solder members on the first substrate to enter the plurality of apertures comprises applying a vacuum to the plurality of apertures.  
     
     
         19 . The method of  claim 17  and further comprising applying an adhesive film to the first substrate to secure the plurality of solder members in the plurality of apertures.  
     
     
         20 . The method of  claim 17  wherein the first substrate comprises aluminum.  
     
     
         21 . The method of  claim 17  and further comprising placing a cover on top of the solder members to secure the plurality of solder members in the plurality of apertures.  
     
     
         22 . The method of  claim 21  wherein the cover comprises a non-solderable material.  
     
     
         23 . The method of  claim 21  wherein the cover comprises aluminum.  
     
     
         24 . The method of  claim 17  wherein the step of forming a plurality of apertures in a first substrate comprises forming a plurality of apertures in a pattern to match a pattern of contact pads on a second substrate.  
     
     
         25 . The method of  claim 24  wherein the second substrate comprises a ball grid array.  
     
     
         26 . The method of  claim 24  wherein the second substrate comprises a flip-chip electronic package.  
     
     
         27 . The method of  claim 17  wherein the plurality of solder members comprise a plurality of solder balls.  
     
     
         28 . The method of  claim 19  wherein the adhesive film is operable to lose its adhesive properties upon application of ultraviolet light.  
     
     
         29 . A method for forming a decal for transferring solder members to substrate comprising the steps of: 
 forming a plurality of indentations in a first substrate;    placing a plurality of solder members on the first substrate; and    allowing the plurality of solder members on the first substrate to enter the plurality of indentations to form a decal having a plurality of solder members.    
     
     
         30 . The method of  claim 29  wherein the step of allowing the plurality of solder members on the first substrate to enter the plurality of indentations comprises allowing the plurality of solder members to fall into the plurality of apertures under the influence of a gravitational field.  
     
     
         31 . The method of  claim 29  wherein the first substrate comprises a non-solderable material  
     
     
         32 . The method of  claim 29  wherein the first substrate comprises aluminum.  
     
     
         33 . The method of  claim 29  wherein the step of forming a plurality of indentations in a first substrate comprises forming a plurality of indentations in a pattern to match a pattern of contact pads on a second substrate.  
     
     
         34 . The method of  claim 29  wherein the indentations comprise a frustum.  
     
     
         35 . The method of  claim 33  wherein the second substrate comprises a ball grid array.  
     
     
         36 . The method of  claim 33  wherein the second substrate comprises a flip-chip package.  
     
     
         37 . The method of  claim 33  wherein the plurality of solder members comprises a plurality of solder balls.  
     
     
         38 . A method for attaching solder members to a substrate comprising the steps of: 
 placing a photomask adjacent a film to expose a plurality of exposed areas and shield a plurality of shielded areas, the film being adhesive and further being operable to lose a portion of its adhesiveness when exposed to ultraviolet light;    applying ultraviolet light to the exposed areas of the film;    placing a plurality of solder members on the film;    allowing the plurality of solder members to adhere to the plurality of shielded areas of the film;    aligning the film with a first substrate; and    transferring the solder members on the film to the first substrate.    
     
     
         39 . The method of  claim 38  wherein the step of aligning the film with the first substrate further comprises bringing the plurality of solder members into contact a portion of the first substrate.  
     
     
         40 . The method of  claim 38  wherein the step of transferring the solder members comprises heating the solder members.  
     
     
         41 . The method of  claim 38  wherein the step of transferring the solder members comprises a solder reflow process.  
     
     
         42 . The method of  claim 38  and further comprising the step of forming the photomask to have a pattern of photomask regions corresponding to a pattern of contact pads on the first substrate.  
     
     
         43 . The method of  claim 38  wherein the adhesive film comprises a first surface and a second surface and the step of allowing the plurality of solder members to adhere to the plurality of shielded areas of the film comprises the step of allowing the plurality of solder members to adhere to the first surface and further comprising the step of applying ultraviolet light to the second surface to facilitate removal of the film from the solder members.  
     
     
         44 . The method of  claim 43  wherein the step of transferring the solder members comprises a solder reflow process and further comprising removing the film before the solder reflow process.  
     
     
         45 . The method of  claim 38  wherein the step of aligning the film with a first substrate comprises aligning the film with a ball grid array.  
     
     
         46 . The method of  claim 38  wherein the step of aligning the film with a first substrate comprises aligning the film with a flip-chip electronic package.  
     
     
         47 . The method of  claim 38  wherein the step of placing a plurality of solder members on the film comprises placing a plurality of solder balls on the film.