The present invention relates in general to integrated circuit packaging, and more particularly to a ball grid array integrated circuit package with improved thermal characteristics.
High performance integrated circuit (IC) packages are well known in the art. Improvements in IC packages are driven by industry demands for increased thermal and electrical performance and decreased size and cost of manufacture
In general, array packaging such as Tape Ball Grid Array (TBGA) packages provide a high density of interconnects relative to the surface area of the package. Typical TBGA packages include a flexible circuit tape substrate and a semiconductor die attached to the substrate by a die adhesive. Gold wire bonds electrically connect the die to circuitry of the substrate and the wire bonds and die are encapsulated in a molding material. Solder balls are disposed on the bottom surface of the substrate for signal transfer.
Typically, array packaging, such as ball grid array (BGA) packages provide for a high density package including a convoluted signal path, giving rise to high impedance and an inefficient thermal path which results in poor thermal dissipation performance. With increasing package density, the spreading of heat generated by the device is increasingly important.
Further improvements in thermal and electrical performance are still desirable in order to meet industry demands.
In one aspect of the present invention, there is provided a cavity-down ball grid array package having a flexible circuit tape including a flexible tape laminated to a conductor layer. The flexible circuit tape has an aperture therein. A thermally conductive heat spreader is fixed to a first surface of the flexible circuit tape and the heat spreader has a cavity aligned with the aperture of the flexible circuit tape. A semiconductor die is mounted to the heat spreader in a die-down configuration in the cavity. A thermally conductive die adapter is fixed to the semiconductor die such that a portion of the die adapter protrudes from the cavity. A plurality of wire bonds connect the semiconductor die to bond sites on the second surface of the flexible circuit tape. An encapsulating material encapsulates the semiconductor die and the wire bonds and a plurality of solder balls are disposed on a second surface of the flexible circuit tape, in the form of a ball grid array.
In another aspect of the present invention, there is provided a method of fabricating a cavity-down ball grid array package. The method includes providing a flexible circuit tape including a flexible tape laminated to a conductor layer, the flexible circuit tape having an aperture therein, fixing a thermally conductive heat spreader to a first surface of the flexible circuit tape, the heat spreader having a cavity aligned with the aperture of the flexible circuit tape. The method further includes mounting a semiconductor die to the heat spreader in a die-down configuration in the cavity, and attaching a thermally conductive die adapter to the semiconductor die such that a portion of the die adapter protrudes from the cavity and wire bonding the semiconductor die to bond sites on the second surface of the flexible circuit tape. The semiconductor die and the wire bonds are encapsulated in an encapsulating material and a plurality of solder balls are fixed on a second surface of the flexible circuit tape, in the form of a ball grid array.
Advantageously a direct thermal path from the semiconductor die to the printed circuit board, is provided. In one aspect, a plurality of thermally conductive portions are employed that together form an adapter. In a particular aspect, non-electrically conductive adapter portions are employed. In another particular embodiment, electrically conductive adapter portions are employed and wire bonds connect the semiconductor die to portions of the die adapter, which perform as a solid power or ground.
The present invention will be better understood with reference to the following drawings in which like numerals denote like parts and wherein:
Referring to
The package 120 includes a flexible circuit tape 122 including a flexible tape laminated to a conductor layer. The flexible circuit tape 122 has an aperture therein. A thermally conductive heat spreader 124 is fixed to a first surface of the flexible circuit tape 122 and the heat spreader 124 has a cavity aligned with the aperture of the flexible circuit tape 122. A semiconductor die 126 is mounted to the heat spreader 124 in a die-down configuration in the cavity. A thermally conductive die adapter 134 is fixed to the semiconductor die 126 such that a portion of the die adapter 134 protrudes from the cavity. A plurality of wire bonds 128 connect the semiconductor die 126 to bond sites on the second surface of the flexible circuit tape 122. An encapsulating material 130 encapsulates the semiconductor die 126 and the wire bonds 128 and a plurality of solder balls 132 are disposed on a second surface of the flexible circuit tape 122, in the form of a ball grid array.
A method for fabricating the package 120 will now be described in more detail, with reference to
Referring to
The heat spreader 124, formed of thermally conductive material such as a metallic or suitable ceramic material, including a die-cavity therein, is fixed to the flexible circuit tape 122 using a tape adhesive such that the die-cavity is aligned with the aperture in the flexible circuit tape 122 (
Next, the semiconductor die 126 is mounted in the cavity of the heat spreader 124, in a die-down configuration, using conventional die attach technique, such as epoxy attach and curing (
The thermally conductive die adapter 134 is then mounted on the semiconductor die 126 such that a portion of the die adapter 134 protrudes from the cavity (
Wire bonds 128 are then bonded between pads of the semiconductor die 126 and the wire bonding sites of the flexible circuit tape (
Next, the semiconductor die 126 and wire bonds 128 are encapsulated in a glob-top encapsulating material 130 such that the outer surface of the die adapter 134 (the adapter surface that is opposite the surface that is attached to the semiconductor die 126), is exposed (
A plurality of solder balls 132 are attached to the solder ball pads of the flexible circuit tape 122 to form a ball grid array (
As stated hereinabove the cavity-down package 120 is preferably gang fabricated. Thus, the package is singulated using a saw or punch technique. The singulated package is ready for attachment to a printed circuit board, as shown in
Reference is now made to
As shown in
Glob top encapsulation material 130 is added in
Other embodiments and variations may occur to those of skill in the art. For example, the size and shape of many of the elements can differ while still performing the same functions. The particular wiring configuration may differ. Any suitable number of portions of the die adapter can be employed. Portions of the die adapter can be electrically conductive or can be electrically non-conductive and the die adapter portions can be electrically isolated from each other or can be electrically connected. Portions of the die adapter of the embodiment of
This is a Continuation of U.S. patent application Ser. No. 10/694,511, filed Oct. 27, 2003, now U.S. Pat. No. 6,984,785.
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Number | Date | Country | |
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Child | 11191678 | US |