This application claims the priority benefit of Taiwan application serial no. 96111252, filed on Mar. 30, 2007. All disclosure of the Taiwan application is incorporated herein by reference.
1. Field of the Invention
The present invention is related to a bonding structure which utilizes a conductive layer on compliant bumps to electrically connect two substrates.
2. Description of Related Art
Nowadays chips are mostly fabricated by silicon wafers. A plurality of chips is formed after silicon wafers undergo a semiconductor process and a cutting process. The chips need to be packaged on a package substrate and be further assembled on electronic products (such as computers, mobile phones or liquid crystal display devices) via the package substrate, or be directly assembled with a circuit board (a chip on wiring board, COB, for example) or a glass substrate (a chip on glass, COG, for example). The chips would then function properly.
Usually, the chips are electrically connected to the circuit board, the package substrate or the glass substrate by a flip chip technology or a wire bonding technology. As far as the flip chip technology is concerned, a plurality of metal pads of the chip are connected to a plurality of pads on the package substrate, the circuit board or the glass substrate by solder or metal bumps, and then the chip is assembled on the package substrate, the circuit board or the glass substrate.
The present invention provides a compliant bump structure including a substrate, at least a first polymer bump, at least a second polymer bump and at least a conductive layer. The substrate has at least a pad located on a surface of the substrate. The first polymer bump is disposed on the pad. The second polymer bump is disposed on the surface outside the pad of the substrate. The conductive layer is disposed on the first polymer bump and the second polymer bump.
The invention further provides a bonding structure including a first substrate, at least a first polymer bump, at least a second polymer bump and at least a conductive layer and a second substrate. The first substrate has at least a first pad located on a surface thereof. The first polymer bump is disposed on the first pad. The second polymer bump is disposed on the surface outside the pad of the first substrate. The conductive layer is disposed on the first polymer bump and the second polymer bump. The second substrate has at least a second pad located on a surface of the second substrate. The conductive layer is connected to the second pad.
The invention also provides a bonding process. A compliant bump structure including a substrate, at least a first polymer bump, at least a second polymer bump and at least a conductive layer is provided. The substrate has at least a first pad located on a surface of the substrate. The first polymer bump is disposed on the pad. The second polymer bump is disposed on the surface outside the pad of the substrate. The conductive layer is disposed on the first polymer bump and the second polymer bump. Afterwards, a second substrate is provided. The second substrate has at least a second pad located on a surface of the second substrate. Next, the conductive layer is connected to the second pad.
The same reference numerals represent the same or similar elements in the following embodiments.
In the present embodiment, a portion of the conductive layer 240 on at least one of the first polymer bumps 220 may be connected to another portion of the conductive layer 240 on at least one of the second polymer bumps 230. In addition, at least two portions of the conductive layer 240 respectively on at least two of the second polymer bumps 220 may be connected. Moreover, the height of the second polymer bumps 230 relative to the substrate 210 may be smaller than that of the first polymer bumps 220 relative to the substrate 210.
During the bonding process, the bonding adhesive 320 is first disposed between the first substrate 210 and the second substrate 310. Thereafter, the bonding adhesive 320 is softened, and the first substrate 210 and the second substrate 310 are compressed. As a result, the bonding adhesive 320 fills the space between the first substrate 210 and the second substrate 310, and portions of the conductive layer 240 penetrate through the bonding adhesive 320 and are connected to the second pads 312 respectively. Finally, the bonding adhesive 320 is cured. The method for curing the bonding adhesive 320 may be a heating process, an ultraviolet irradiation process, an ultrasonic-wave vibration process or an infrared irradiation process, or at least two of the aforementioned methods may be applied simultaneously.
In the present embodiment, the polymer protective layer 250 and the second polymer bumps 230 may be integrally formed. Additionally, the first polymer bumps 220 may also be integrally formed with the polymer protective layer 250 and the second polymer bumps 230. Besides, portions of the conductive layer 240 may further penetrate through the polymer protective layer 250 and be connected to the surface 210a of the substrate 210.
To sum it up, in the present invention, the first pads of the first substrate are electrically connected to the second pads of the second substrate with a plurality of first polymer bumps and portions of the conductive layer located on the first polymer bumps respectively. Further, the pressure generated during the bonding process of the first and second substrates is distributed by the second polymer bumps in the invention. Consequently, the conductive layer is prevented from chapping so as to ensure its connection to the second pads. In addition, the conductive layer disposed on the second polymer bumps further has the function of heat conductivity.
It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.
Number | Date | Country | Kind |
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96111252 | Mar 2007 | TW | national |