Molding assembly for wafer scale molding of protective caps

Abstract

A mold assembly ( 100 ) formed of a pair of molds ( 102, 104 ) and a pair of release plates ( 118, 120 ). The molds ( 102, 104 ) have holes ( 126 ) which extend from outer surfaces into the mold cavities ( 106 ). The release plates ( 118, 120 ) have pins ( 122, 124 ) which pass into the holes ( 126, 128 ). When molding is finished, the molds ( 102, 104 ) are moved toward the release plates ( 118, 120 ). The pins ( 122, 124 ) contact the molded article(s) ( 134 ) and hold them in position as the molds ( 102, 104 ) are withdrawn.

I claim:  
     
         1 . A molding assembly including: 
 a first mold and a second mold a having first and second molding surfaces respectively for molding a sheet of thermoplastic material placed therebetween, which, when assembled, define at least one cavity there between, the first mold including at least one a first aperture extending from an outer surface to the first molding surface;    a release mechanism for removing the first mold from the second mold after molding of the sheet, said release mechanism including at least one first pin which extends into a respective first aperture;    said first mold movable relative to the second mold and said at least one first pin between a molding position and a release position;    whereby, in the molding position, the first and second molds are in contact or close together and said at least one first pin extends into a respective first aperture from the outer surface but does not extend out of the respective aperture beyond the molding surface, and,    in the release position, the first and second molds are remote from each other and said at least one first pin extends into respective first apertures from the outer surface and extends out of the respective first aperture beyond the first molding surface, wherein the first and second molds are formed substantially of silicon or silicon alloy.    
     
     
         2  The assembly of  claim 1  wherein the molds are substantially planar and the first release mechanism includes a substantially planar plate having said at least one pin extending generally perpendicular to the plane of the plate.  
     
     
         3 . The assembly of  claim 1  wherein the at least one first aperture in the first mold is located toward the center of the respective cavity.  
     
     
         4 . The assembly of  claim 1  wherein the first release mechanism and the outer surface of the first mold define at least part of a substantially closed cavity therebetween and further including a vacuum source for applying a vacuum to the substantially closed cavity to move the first mold from the molding position to the release position.  
     
     
         5 . The assembly of  claim 4  further including a source of above ambient pressure for applying an above ambient pressure to the cavity to move the first mold from the release position to the molding position.  
     
     
         6 . The assembly of  claim 1  wherein the second mold includes at least one second aperture extending from an outer surface to the cavity defining surface, and further including a second release mechanism for removing the second mold from the sheet after molding of the sheet, said second release mechanism including at least one second pin which extends into a respective second aperture in the second mold.  
     
     
         7 . The assembly of  claim 6  wherein the second apertures in the second mold are located toward the edges of the respective cavity.  
     
     
         8 . The assembly of  claim 1  wherein at least part of at least the first or second mold is at least partially transparent or translucent to electromagnetic radiation having wavelengths in the range of about 1000 nm to about 5000 nm.  
     
     
         9 . The assembly of  claim 1  wherein at least part of the first release mechanism is at least partially transparent or translucent to electromagnetic radiation having wavelengths in the range of about 1000 nm to about 5000 nm.  
     
     
         10 . The assembly of  claim 1  wherein at least part of the first release mechanism is formed of a semiconductor material.  
     
     
         11 . A method of manipulating a sheet of thermoplastic material using the assembly of  claim 1 , the method including: 
 a) sandwiching the sheet between the two molds:    b) heating the sheet to a plastic state;    c) urging the two molds together to plastically deform the sheet;    d) drawing the first mold away from the sheet whilst maintaining the at least one first pin in contact with the sheet; and,    e) removing the at least one first pin from being in contact with the sheet.    
     
     
         12 . The method of  claim 11  further including, before step d) or after step e), bonding the molded sheet to a wafer  
     
     
         13 . The method of  claim 11  including: 
 f) providing a second mold including at least one second aperture extending from an outer surface to the cavity defining surface, and a second release mechanism for removing the second mold from the sheet after molding of the sheet, said second release mechanism including at least one second pin which extends into a respective second aperture in the second mold.  
 g) drawing the second mold away from the sheet whilst maintaining said at least one second pin in contact with the sheet; and  
 h) removing the at least one second pin from being in contact with the sheet.  
 
     
     
         14 . The method of  claim 11  wherein step c) includes applying an above ambient pressure to the working cavity between the first mold and the first release mechanism.  
     
     
         15 . The method of  claim 11  wherein step d) includes applying a below ambient pressure to the working cavity between the first mold and the first release mechanism to draw the first mold away from the second mold  
     
     
         16 . The method of  claim 14  wherein step c) includes applying an above ambient pressure to the working cavity between the second mold and the second release mechanism.  
     
     
         17 . The method of  claim 14  wherein step g) includes applying a below ambient pressure to the working cavity between the second mold and the second release mechanism to draw the second mold away from the sheet.  
     
     
         18 . The method of  claim 11  wherein step b) includes irradiating the thermoplastic material with electromagnetic radiation having wavelengths in the range of about 1000 nm to about 5000 nm.  
     
     
         19 . The method of  claim 11  further including applying the caps to a wafer after step c) and before step d).  
     
     
         20 . The method of  claim 11  further including applying an etch to the caps to remove extraneous material from between the caps.  
     
     
         21 . The method of  claim 21  wherein the etch is applied before step d).  
     
     
         22 . The method of  claim 21  wherein the etch is applied after step d).  
     
     
         23 . The method of  claim 14  wherein steps g) and h) occur after step c) and before step d).