Foldover packages and manufacturing and test methods therefor

Abstract

A microelectronic fold package is formed from an in-process unit including an internal unit such as a chip and a tape defining a bottom run extending beneath the internal unit, a top run extending above the internal unit and a fold connecting said top and bottom runs. The in-process unit is engaged between a pair of elements having flat surfaces so that these elements form the top and bottom runs to a substantially flat condition at least in regions between the internal unit and the fold and so that the engagement elements form the fold to a height equal to the height of the internal unit.

1 . A method of making a fold package comprising the steps of: 
 (a) providing an in-process unit including one or more internal elements defining a internal unit and a carrier including a tape having a dielectric layer, said tape defining a bottom run extending beneath the internal unit, a top run extending above the internal unit and a fold connecting said top and bottom runs; and    (b) engaging the in-process unit between a pair of engagement elements having flat surfaces so that said engagement elements form said top and bottom runs to a substantially flat condition at least in regions between said internal unit and said fold and so that said engagement elements form said fold to a height equal to the height of said internal unit.    
   
   
       2 . A method as claimed in  claim 1  further comprising the step of leaving said fold unconstrained with respect to horizontal movement towards or away from said internal unit during said engaging step.  
   
   
       3 . A method as claimed in  claim 1  wherein said internal unit includes at least one adhesive layer in contact with at least one of said runs, the method further comprising the step of curing said at least one adhesive layer during said engaging step.  
   
   
       4 . A method as claimed in  claim 3  wherein said internal unit includes at least one microelectronic element and a said at least one adhesive layer includes a top adhesive layer disposed between a surface of said microelectronic element and said top run, said step of curing said at least one adhesive layer including the step of curing said top adhesive layer.  
   
   
       5 . A method as claimed in  claim 1  wherein said step of providing said in-process unit includes mounting said microelectronic element above a first mounting portion of said tape so that a fold portion and a second mounting portion of said tape project in a lengthwise direction beyond a first edge of said microelectronic element and then bending fold portion so that said second mounting portion of said tape overlies said microelectronic element and forms at least a part of said top run.  
   
   
       6 . A method as claimed in  claim 5 , said step of providing said in-process unit further comprising the step of temporarily attaching said top run to said microelectronic element so that said temporary attachment holds said top run in place between said bending step and said engagement step.  
   
   
       7 . A method as claimed in  claim 6  wherein said step of providing said in process unit includes the step of providing a tacky top adhesive layer disposed between said microelectronic element and said top run before completion of said bending step, said step of temporarily attaching including tacking said top run to said microelectronic element using said top adhesive layer.  
   
   
       8 . A method as claimed in  claim 7  further comprising curing said top adhesive layer during said engaging step.  
   
   
       9 . A method as claimed in  claim 5  wherein said tape includes a first set of electrically conductive elements on said first mounting portion and a second set of electrically conductive elements on said second mounting portion, said bending step being performed so as to place said second set of electrically conductive elements in a preselected spatial relation with said first set of conductive elements.  
   
   
       10 . A method as claimed in  claim 9  wherein said tape includes a first set of registration features on said first mounting portion and a second set of registration features on said second mounting portion, said bending step including controlling the positions of said mounting portions using said registration features.  
   
   
       11 . A method as claimed in  claim 10  wherein said registration features include holes extending through tape, said controlling step including engaging said holes on one or pins.  
   
   
       12 . A method as claimed in  claim 1  wherein said tape includes electrically conductive traces extending between said top and bottom runs by way of said fold.  
   
   
       13 . A method as claimed in  claim 1  wherein the entirety of said top run and the entirety of said bottom run are engaged with said flat surfaces during said engagement step.  
   
   
       14 . A group comprising a plurality of fold packages, each said package having: 
 (a) a internal unit including one or more internal elements, said internal elements including at least one microelectronic element;    (b) a tape having a bottom run extending beneath said internal unit, a top run extending above said internal unit and a fold interconnecting said top and bottom runs, said fold being offset from said internal unit by an offset distance in a horizontal direction, said tape having a first set of electrically conductive elements on said bottom run, a second set of electrically conductive elements on said top run and electrically conductive traces extending between said top and bottom runs by way of said fold; and    the microelectronic element, first set of conductive elements and second set of conductive elements in each one of said fold packages being identical in function to the corresponding elements in other ones of said fold packages, the internal units in different ones of said fold packages having different heights, the offset distances in different ones of said fold packages differing from one another such that fold packages having greater internal unit heights have lesser offset distances.    
   
   
       15 . A group as claimed in  claim 14  wherein, in each said fold package, the top and bottom runs are substantially flat and parallel to one another.  
   
   
       16 . A group as claimed in  claim 14  wherein, in each said fold package, the tape has an inner surface facing inwardly toward the internal unit in and an outer surface facing away from the internal unit, and the first and second sets of conductive elements include first and second sets of terminals exposed at the outer surface of the tape.  
   
   
       17 . An assembly including a group of fold packages as claimed in  claim 16 , wherein said fold packages are mechanically and electrically connected to one another.  
   
   
       18 . An assembly as claimed in  claim 17  wherein said fold packages are stacked one atop the other whereby said stacked fold packages define interfaces between adjacent ones of said fold packages, the top run of one said fold packages confronting the bottom run of another one of said fold packages at each said interface, the terminals on said confronting runs being connected to one another.  
   
   
       19 . An assembly as claimed in  claim 16  wherein, in each said fold package, the first and second sets of terminals are disposed in substantially identical arrays aligned with one another.  
   
   
       20 . A method of testing a fold package including a tape and an internal unit, a tape having a bottom run disposed below said internal unit, a top run disposed above said internal unit and a fold interconnecting said top and bottom runs offset from said internal unit in a horizontal direction, the method including the step of advancing a test fixture toward the package so that the fixture engages the fold and displaces the fold toward said internal unit.  
   
   
       21 . A method as claimed in  claim 20  wherein the test fixture has an elongated edge and said advancing step is performed so that said edge extends in a vertical direction and so that said edge engages the fold.  
   
   
       22 . A method as claimed in  claim 20  wherein said advancing step is performed so as to apply a predetermined force to the fold.  
   
   
       23 . A method as claimed in  claim 20  wherein said advancing step is performed so as to apply a predetermined displacement to the fold.