Metal working – Barrier layer or semiconductor device making
Reexamination Certificate
1999-05-11
2001-02-20
Graybill, David E. (Department: 2814)
Metal working
Barrier layer or semiconductor device making
Reexamination Certificate
active
06190425
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to memory devices and, more particularly, to a memory bar for use in expanding the capacity of, for example, a high density multichip module (MCM).
For the past several years, substantial attention has been directed to the field of memory modules including, for example, single inline memory modules (SIMMs) and dual inline memory modules (DIMMs). Such modules are useful, for example, in expanding the memory of a personal computer or other computing system, and the market for such modules is extremely competitive. In short, there is intense pressure within the memory module market to provide modules with increased capacity for less cost.
In view of the competitiveness of the memory module market, it is believed that those skilled in the art would find systems and methods for expanding the capacity of memory modules to be quite useful.
SUMMARY OF THE INVENTION
In one innovative aspect, the present invention is directed to a memory bar that may be used to dramatically increase the capacity of a high-density multichip memory module and to methods of manufacturing the same.
In one presently preferred embodiment, the memory bar provides a means for integrating numerous sets of identical dynamic random access memory (DRAM) integrated circuit packages by sandwiching the memory bar between respective pairs of packages. Moreover, by using a memory bar in accordance with the present invention, it is possible to literally double the memory capacity of conventional high density multichip modules such as DIMMs and SIMMs. The reason for this is that the use of a memory bar in accordance with the present invention allows for twice the number of memory chips to be mounted upon each side of a memory module.
A memory bar in accordance with the present invention may be viewed as a multichip carrier device. For example, the memory bar may comprise a printed circuit board structure having a plurality of land patterns provided on an upper surface and a lower surface thereof. The land patterns provided on the upper surface of the memory bar provide contacts for a first IC package, and the land patterns on the bottom surface of the memory bar provide contacts for a second IC package. In a preferred form, a gap of about 10 mils is provided between the top memory package and the bottom memory package. Such a gap allows for improved thermal dissipation by the resulting multi-chip memory structure. Once the IC chips are affixed to the memory bar, the memory bar may be mounted on, for example, one side of a dual inline memory module (DIMM), thus greatly increasing the amount of memory that is conventionally provided on one side of such a module. Of course, a similar memory bar structure may be used to increase the memory capacity on an opposite side of the dual inline memory module.
In another innovative aspect, the present invention is directed to a method of manufacturing a stacked memory product. In such an embodiment, a memory bar substrate is prepared, a first set of memory chips is placed on one side of the memory bar substrate and soldered into position, the memory bar substrate is inverted (or “flipped over”), a second set of memory chips is placed in an inverted orientation into the apertures provided within the memory bar substrate such that the chips within the second set are suspended within the apertures by their respective lead pins, and finally, the second set of memory chips is bonded to the memory bar substrate by soldering. In alternative embodiments, the first set of memory chips may be place in an inverted orientation within the apertures provided within the memory bar substrate, and the second set of chips may be placed on the memory bar in an upright position.
Accordingly, it is an object of the present invention to provide a memory bar for expanding the memory capacity of high-density memory modules.
It also is an object of the present invention to provide an innovative memory bar structure that is useful during the assembly of high-density memory modules.
Other objects and features of the present invention will become apparent from consideration of the following description taken in conjunction with the accompanying drawings.
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Darwish Rashwan B.
Huynh Trung
Graybill David E.
Lyon & Lyon LLP
Zomaya Group, Inc.
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