COF packaged semiconductor

Details COF packaged semiconductor COF packaged semiconductor

2001-02-05

2004-05-18

Flynn, Nathan J. (Department: 2826)

Active solid-state devices (e.g., transistors, solid-state diode

Encapsulated

With heat sink embedded in encapsulant

C257S707000, C257S712000, C257S713000

Reexamination Certificate

active

06737754

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to packaged semiconductors. More specifically, the invention relates to a chip-on-flex (“COF”) packaged semiconductor device that can effectively dissipate heat generated by an enclosed die.
BACKGROUND OF THE INVENTION
Because COF packaging enables a semiconductor die to be bonded directly to a multilayer laminate, it has become a key downsizing technology for semiconductor devices. Attaching the die to such a laminate facilitates short lead lengths and a flexible interconnect. Because COF technology requires less space for the I/O interconnects, it minimizes the resulting device's footprint. Driven by the need for miniaturization and flexibility, COF packaging techniques have been adopted for components used in electronic devices such as cameras, pagers, disk drives, LCDs, printers, smart cards, hearing aids and other devices where form factor constraints may be severe.
Although COF packaging technology is currently used for relatively small die with low power requirements, it is not particularly suitable for large, high power die—e.g., a microprocessor die. The large mismatch between the coefficients of thermal expansion (“CTE”) of such a die and the molding compound that encapsulates it can create significant stress and warpage, which can cause reliability failures and processing difficulties. In addition, a highly powered die generates significant heat that must be dissipated to maintain an acceptable servicing temperature. Because COF packaging encloses the back side of the die with the molding compound, such packaging does not efficiently conduct heat.
Accordingly, there is a need for an improved COF packaged device that does not sustain severe stress or warpage caused by large CTE mismatch between the die and the molding compound. In addition, there is a need for such a device that may effectively transfer heat from the die.
SUMMARY OF THE INVENTION
An improved semiconductor device is disclosed. That device includes a multilayer laminate made from thermally stable, flexible polymer film and a semiconductor die that contacts the laminate. The device also includes a molding compound—which contacts both the laminate and the sides of the die, but not the die's top or bottom surface—and a heat dissipation member that contacts substantially all of the die's top surface.


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