Active solid-state devices (e.g. – transistors – solid-state diode – Combined with electrical contact or lead – Chip mounted on chip
Reexamination Certificate
1997-09-24
2001-09-25
Clark, Sheila V. (Department: 2815)
Active solid-state devices (e.g., transistors, solid-state diode
Combined with electrical contact or lead
Chip mounted on chip
C257S686000, C257S778000
Reexamination Certificate
active
06294838
ABSTRACT:
INTRODUCTION
This invention relates to multiple chip module, in particular to ball grid array package.
With ever increase in circuit complexity and demand for miniaturization, the area of an integrated circuits becomes larger and the number of connections to the IC tends to increase. One popular package to serve this trend is the ball grid array (BGA) package. In this package, printed wiring is deposited on a plastic, ceramic, polyimide, etc. substrate as a lead frame. The IC is flip-chip bonded or wire bonded to the printed wiring substrate. These printed wires are connected to the bottom of the substrate through plated-through via holes. These leads are terminated at the bottom of the substrate in the form of beads or balls, and arranged in a matrix array. This array of beads can then be mounted on a printed circuit board by mating the beads with solder bumps on the printed circuit board.
However, the demand for more leads is ever increasing. One way to accommodate more leads is to use a substrate of multiple layer lamina. Each layer has its own printed wiring which are connected to the flip chip IC through via holes. The multiple layer lamina allows more terminals to be connected to the IC and to be interconnected. However, the use of lamina substrate adds to the cost of packaging.
Another problem of IC design is that the number of bonding pads on an IC is limited, because the area occupied by a bonding pad is relatively large and space must be allowed between pads. For small IC chip, there cannot be a large number of bonding pads. Sometimes it is desirable to have more bonding pads than allowed.
A multiple-chip module (MCM) usually occupies more area than the area of a single IC chip. It is not convenient to mount multiple chips on a BGA substrate.
SUMMARY
An object of the present invention is to increase the allowable IC leads in a BGA package. Another object of the present invention is to mount more than one IC chip on a BGA package as a multiple-chip module. Still another object of the present invention is to permit fewer layers of a BGA lamina. A further object of the present invention is to provide a common ground and heat sink for two IC chips.
These objects are achieved by stacking two IC chips back to back and gluing them together. The lower chip is flip-chip bonded to the lead frame or substrate of a BGA package, and the upper chip is wire bonded to the printed wiring of the lead frame. The common contact between the two chips can serve a common electrical terminal, a shield against crosstalk, and/or serve as a heat sink.
REFERENCES:
patent: 4761681 (1988-08-01), Reid
patent: 5151769 (1992-09-01), Immorlica et al.
patent: 5394303 (1995-02-01), Yamaji
patent: 5644167 (1997-07-01), Weiler et al.
Clark Sheila V.
Lin H. C.
Utron Technology Inc.
LandOfFree
Multi-chip stacked package does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Multi-chip stacked package, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Multi-chip stacked package will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2515192