High density, high frequency memory chip modules having thermal management structures

Abstract

The present invention features an ultra high density, high frequency, three-dimensional electronic circuit package suitable for constructing high capacity, high speed computer memory cards and the like. A demountable contact system allows easy test and/or burn-in. A memory card has a number of electrical receptacles adapted to receive a daughter card. The daughter card has memory devices attached to it and a corresponding number of electrical connectors placed along at least one edge, adapted to detachably mate with the electrical receptacles of the memory card. The demountable connectors allow easy rework of the package before optional, permanent solder attach. Bare dies or thin packages are mounted onto daughter cards, which in turn are mounted onto either a motherboard or memory card using pin/hole technology. The daughter cards may be equipped with structures such as ground planes, etc. to minimize electrical noise, control and match impedances and signal path lengths, and maintain signal synchronization (i.e., controlling skew). The inventive memory daughter cards may also contain thermal management structures contacting the chips, which conduct heat away from the chips. Such structures may be constructed by interleaving heat-spreading fins between the individual chip components and/or daughter boards.

What is claimed is:  
     
         1 . A high-density, high frequency memory package comprising: 
 a) a memory card having a plurality of electrical receptacles adapted to receive a daughter card; and    b) a daughter card having at least one memory device attached thereto and a plurality of electrical connectors adapted to mate with said electrical receptacles, said plurality of electrical connectors being disposed along at least one edge of said daughter card.    
     
     
         2 . The high-density, high frequency memory package as recited in  claim 1 , wherein said plurality of electrical connectors is adapted to detachably mate with said electrical receptacles.  
     
     
         3 . The high-density, high-frequency memory package as recited in  claim 2 , wherein said daughter card comprises a multi-layer printed circuit board (PCB).  
     
     
         4 . The high-density, high frequency memory package as recited in  claim 1 , wherein said memory device is packaged at least in one from the group of: bare chip, thin, small-outline packages (TSOP), and chip-scale packages (CSP).  
     
     
         5 . The high-density, high frequency memory package as recited in  claim 4 , wherein said attachment of said unpackaged or packaged memory devices to said daughter card is accomplished by at least one process from the group: flip-chip attachment, wire bond attachment and direct soldering.  
     
     
         6 . The high-density, high frequency memory package as recited in  claim 1 , wherein said electrical receptacles comprise a plurality of holes disposed in said memory card.  
     
     
         7 . The high-density, high frequency memory package as recited in  claim 6 , wherein at least one of said plurality of holes comprises a plated through hole.  
     
     
         8 . The high-density, high frequency memory package as recited in  claim 7 , wherein at least one of said plurality of holes further comprises a conductive member protruding radially into said hole.  
     
     
         9 . The high-density, high frequency memory package as recited in  claim 8 , wherein said electrical connectors comprise pins adapted to fit into said holes, said pins being mechanically, detachably retained in said holes by said conductive members, whereby an electrical connection between said daughter card and said memory card is established.  
     
     
         10 . The high-density, high frequency memory package as recited in  claim 9 , wherein said daughter card comprises a front surface and a rear surface and said pins are disposed along at least one edge on both said front and said rear surface.  
     
     
         11 . The high-density, high frequency memory package as recited in  claim 10 , wherein at least one of said pins is offset from at least one adjacent pin.  
     
     
         12 . The high-density, high frequency memory package as recited in  claim 10 , wherein said pins have a cross-section having a shape from the group: round, oval, square, rectangular and polygonal.  
     
     
         13 . The high-density, high frequency memory package as recited in  claim 12 , wherein said pins are substantially cylindrical.  
     
     
         14 . The high-density, high frequency memory package as recited in  claim 13 , wherein said daughter card has a predetermined thickness and said pins have a length approximately equal to said thickness.  
     
     
         15 . The high-density, high frequency memory package as recited in  claim 14 , wherein the distal end of said pins is pointed.  
     
     
         16 . The high-density, high frequency memory package as recited in  claim 12 , wherein said pins are tapered.  
     
     
         17 . The high-density, high frequency memory package as recited in  claim 16 , wherein a distal end furthest from said daughter card is substantially pointed.  
     
     
         18 . The high-density, high frequency memory package as recited in  claim 2 , wherein said at least one memory device comprises memory devices from the group of bare memory chips and packaged memory chips.  
     
     
         19 . The high-density, high frequency memory package as recited in  claim 18 , further comprising: 
 c) heat transfer means attached to at least one of said plurality of said memory devices.    
     
     
         20 . The high-density, high frequency memory package as recited in  claim 19 , wherein said heat transfer means comprises thermally conductive heat fins in contact with said memory devices.  
     
     
         21 . The high-density, high frequency memory package as recited in  claim 20 , wherein said at least one daughter card comprises a plurality of cards adjacent to, substantially parallel to, and in contact with one another on said memory card.  
     
     
         22 . The high-density, high frequency memory package as recited in  claim 21 , wherein said at least one of said thermally conductive heat fins is interspersed between said plurality of daughter cards.  
     
     
         23 . The high-density, high frequency memory package as recited in  claim 1 , wherein conductive traces are on the surfaces and internal to daughter cards, with ground planes on the surfaces and internal to said daughter cards, wherein said ground planes and traces are arranged in stripline and microstrip structures.  
     
     
         24 . The high-density, high frequency memory package as recited in  claim 23 , wherein said signal trace path lengths are substantially matched.  
     
     
         25 . A method for assembling a high-density memory package, the steps comprising: 
 a) attaching a plurality of memory devices to at least one daughter card having a plurality of pins along at least one edge thereof, said pins being respectively and operatively connected to said plurality of memory devices;    b) providing a memory board having a plurality of plated through holes adapted to detachably receive said plurality of pins;    c) after said attaching step (a), testing each of said at least one daughter card connected to said memory board;    d) detaching and replacing any daughter card failing said test performed in step (c);    e) retesting said replaced daughter card; and    f) repeating said detaching and replacing step (d) and said retesting step (e) until a completely functional memory package is obtained.    
     
     
         26 . The method for assembling a high-density memory package as recited in  claim 25 , the steps further comprising: 
 g) soldering said at least one daughter card to said memory board upon successful completion of said testing step (c) and retesting step (e).    
     
     
         27 . The method for assembling a high-density memory package as recited in  claim 24 , the steps further comprising: 
 h) placing at least one heat transfer means between predetermined ones of said daughter cards.