Attachment method for stacked integrated circuit (IC) chips

Patent · Fri Jan 01 00:00:00 EST 1999

OSTI ID:872428

Bernhardt, Anthony F ^[1]; Malba, Vincent ^[2]

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1. Berkeley, CA
2. Livermore, CA

An attachment method for stacked integrated circuit (IC) chips. The method involves connecting stacked chips, such as DRAM memory chips, to each other and/or to a circuit board. Pads on the individual chips are rerouted to form pads on the side of the chip, after which the chips are stacked on top of each other whereby desired interconnections to other chips or a circuit board can be accomplished via the side-located pads. The pads on the side of a chip are connected to metal lines on a flexible plastic tape (flex) by anisotropically conductive adhesive (ACA). Metal lines on the flex are likewise connected to other pads on chips and/or to pads on a circuit board. In the case of a stack of DRAM chips, pads to corresponding address lines on the various chips may be connected to the same metal line on the flex to form an address bus. This method has the advantage of reducing the number of connections required to be made to the circuit board due to bussing; the flex can accommodate dimensional variation in the alignment of chips in the stack; bonding of the ACA is accomplished at low temperature and is otherwise simpler and less expensive than solder bonding; chips can be bonded to the ACA all at once if the sides of the chips are substantially coplanar, as in the case for stacks of identical chips, such as DRAM.

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
• DOE Contract Number: W-7405-ENG-48
• Assignee: Regents of University of California (Oakland, CA)
• Patent Number(s): US 5933712
• OSTI ID: 872428
• Country of Publication: United States
• Language: English

Related Subjects

attachment
method
stacked
integrated
circuit
chips
involves
connecting
dram
memory
board
pads
individual
rerouted
form
chip
top
whereby
desired
interconnections
accomplished
via
side-located
connected
metal
lines
flexible
plastic
tape
flex
anisotropically
conductive
adhesive
aca
likewise
stack
corresponding
address
various
line
bus
advantage
reducing
connections
required
due
bussing
accommodate
dimensional
variation
alignment
bonding
temperature
otherwise
simpler
expensive
solder
bonded
substantially
coplanar
stacks
identical
circuit board
method involves
integrated circuit
metal lines
conductive adhesive
stacked integrated
method involve
flexible plastic
metal line
address bus
attachment method
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