This application claims the benefit of Korean Patent Application No. 10-2006-0111226, filed on Nov. 10, 2006, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to an electrical connection between a semiconductor chip and a printed circuit board, and a semiconductor package including the same, and more particularly, to a wiring film to make the electrical connection and a semiconductor package including the wiring film.
2. Description of the Related Art
One of the fundamental stages of fabricating a semiconductor package is electrically connecting a pad of a semiconductor chip to an electrode of a printed circuit board. The connection is often made by wire bonding using gold (Au) wires or by using bumps. A flip chip package or a wafer level package uses bumps to electrically connect a pad of a chip to an electrode of a board.
However, wire bonding has a limit in reducing a loop height of a wire, and is thus not suitable for fabricating a very thin semiconductor package. In the flip chip package or the wafer level package in which the electrical connection is made using bumps, a redistribution layer needs to be formed to redistribute the interconnections so that the pads of the semiconductor chip match the electrodes of the board, which is expensive.
Embodiments of the present invention provide a wiring film that enables a semiconductor package to be thin, simplifies the fabrication process while reducing a unit price for the process, and improves reliability. Other embodiments of the present invention provide a semiconductor package including the wiring film and a method of fabricating the semiconductor package.
According to an embodiment of the present invention, a wiring film includes a base film and first wires arranged on a first surface of the base film. First bumps are respectively positioned on ends of the first wires. A first adhesive layer is also provided to cover the first wires and the first bumps.
The above and other features and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which:
The present invention will now be described more fully with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. This invention may, however, be embodied in many different forms, and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the thicknesses of layers and regions are exaggerated for clarity. Like numbers refer to like elements throughout the specification.
Wiring Film
A wiring film according to an embodiment of the present invention, and a method of fabricating the wiring film, will now be described with reference to
A base film 30 capable of including a number of unit cell regions F_C to be applied to a single package is initially provided. The base film 30 may be composed of a material which has high stability at high temperatures and good insulation, and which is rigid at room temperature but flexible at high temperatures. The base film 30 may be, for example, a polyimide film, a polyester film, or a polyamide film. Preferably, the base film 30 may be the polyimide film.
Wires 32 are formed on a first surface of the base film 30. The wires 32 may be formed by a printing, a jetting, or an imprinting process using a conductive material. These methods can more easily form wires with a small pitch as compared to wire bonding. The wires 32 may be formed of one or more metals, such as gold (Au), silver (Ag), copper (Cu), nickel (Ni), aluminum (Al), tin (Sn), lead (Pb), platinum (Pt), bismuth (Bi), and indium (In).
Bumps 33 and 35 are formed on at least one end of each wire 32. In the embodiment illustrated in
A first adhesive layer 37 is formed on a first surface of the base film 30, to cover the wires 32 and the bumps 33 and 35. The height H37 of the first adhesive layer 37 from the first surface of the base film 30 may be equal to or greater than the height H33 of the bumps 33 and 35. Further, the height H37 of the first adhesive layer 37 may be about 1.1 times or less the height H33 of the bumps 33 and 35. Thus, in some embodiments the height H37 may be between about 1 and about 1.1 times the height H33. Accordingly, while protectively covering the wires 32 and the bumps 33 and 35, the first adhesive layer 37 may be pushed from an upper part of the bumps 33 and 35 by heat and pressure, so that the bumps 33 and 35 are electrically coupled to an electrode on the printed circuit board. The height H37 of the first adhesive layer 37 may be within the range of about 5 to about 30 μm.
A first protection film 41 is further formed on the first adhesive layer 37. The first protection film 41 may be detachable from the first adhesive layer 37.
In the presently illustrated embodiment, a second adhesive layer 38 is further formed on a second surface of the base film 30. The height of the second adhesive layer 38 may be equal to or greater than the height of the first adhesive layer 37. Specifically, the height of the second adhesive layer 38 may be about 16 to about 24 μm.
A second protection film 42 is further formed on the second adhesive layer 38. Like the first protection film 41, the second protection film 42 may be detachable from the second adhesive layer 38.
The wiring film WF in the above described constitution can be rolled for transport and handling. In these instances, the protection films 41 and 42 protect the adhesive layers 37 and 38, the bumps 33 and 35, and the wires 32.
Referring to
A second wire 32b is formed on a second surface of the base film 30. Second bumps 33b and 35b are formed on at least one end of the second wire 32b. In the embodiment illustrated in
Semiconductor Package
Referring to
Referring to
Heat and pressure are applied to the wiring film WF, that is, the base film 30, to connect the bumps 33 and 35 respectively to the pad electrodes 15 and 25. During this process, a first adhesive layer 37 covering the bumps 33 and 35 is pushed from an upper part of the bumps 33 and 35 by the heat and pressure, so that the bumps 33 and 35 are respectively electrically coupled with the pad electrodes 15 and 25. In other words, if a portion of the first adhesive layer 37 covers the bumps, the heat and pressure of the connection process dispose this portion of the adhesive layer 37 so that bumps 33 and 35 are respectively electrically coupled with the pad electrodes 15 and 25.
The wiring film WF, which includes the base film 30 and the wires 32 arranged on the lower surface of the base film 30, is disposed on the board 10 during this connection process. During this process, the bumps 33 are electrically coupled to the board pad electrodes 15 and the bumps 35 are electrically coupled to the chip pad electrodes 25. The adhesive layer 37 arranged at both sides of the bumps 33 and 35 and covering the wires 32, the adhesive layer adhering the base film 30 to the board 10 and the semiconductor chip 20.
Then, the wiring film WF and the substrate S, which are electrically connected and bonded to each other, are then cut into unit packages P-C.
When the board pad electrodes 15 are electrically coupled to the chip pad electrodes 25 by the wiring film WF including the wires, a thin semiconductor package is possible since there are no problems associated with the wire bonding method, such as the limit in reducing the loop height of the wires. Additionally, the process cost is reduced since no redistribution layer is needed. Furthermore, when using the wiring film WF including the adhesive layer 37 on the bumps 33 and 35, no additional adhesive layers need to be formed between the wiring film WF and the board 10 or between the wiring film WF and the semiconductor chip 20. Since the adhesive layer 37 is arranged on both sides of the bumps 33 and 35, the electrical connection between the bumps 33 and 35 and the pad electrodes 15 and 25 is maintained even if the package is bent, thereby improving the reliability of the package.
Referring to
Referring to
The first wiring film WF1 and the board 10 are aligned so that the first bumps 33 and 35 of the first wiring film WF1 respectively correspond to the first pad electrodes 15 and 25. Subsequently, heat and pressure are applied to the first wiring film WF1 so that the first bumps 33 and 35 are respectively connected to the first pad electrodes 15 and 25.
As a result, the first wires 32, which are positioned on the lower surface of the first base film 30, electrically couple the first board pad electrodes 5 with the first chip pad electrodes 25. The first adhesive layer 37 is positioned at both sides of the first bumps 33 and 35, to cover the first wires 32 and to contact the board 10 and the first semiconductor chip 20.
A second semiconductor chip 60 including second chip pad electrodes 65 is positioned on the first wiring film WF1. The second semiconductor chip 60 is connected to the first wiring film WF1 by the upper adhesive layer 38. When using the first wiring film WF1 including the upper adhesive layer 38, it is possible to stack the second semiconductor chip 60 without any additional adhesive layer, thereby reducing the process cost.
A second wiring film WF2 is positioned on the board 10 and the second semiconductor chip 60. The second wiring film WF2 includes a second base film 70, second wires 72 arranged on the lower surface of the second base film 70, second bumps 73 and 75 respectively arranged on the ends of the second wires 72, and a second adhesive layer 77 covering the second wires 72 and the second bumps 73 and 75.
The second wiring film WF2 and the board 10 are aligned so that the second bumps 73 and 75 respectively correspond to the second pad electrodes 55 and 65. Subsequently, heat and pressure are applied to the second wiring film WF2 so that the second bumps 73 and 75 are respectively electrically connected to the second pad electrodes 55 and 65.
As a result, the second wires 72, which are positioned on the lower surface of the second base film 70, electrically couple the second board pad electrodes 55 and the second chip pad electrodes 65. The second adhesive layer 77 is positioned at both sides of the second bumps 73 and 75, to cover the second wires 72 and to contact the board 10 and the second semiconductor chip 60.
Referring to
Second supporting parts 81 and 83 are formed close to the sides of a second semiconductor chip 60 before a second wiring film WF2 is positioned on the second semiconductor chip 60. The second supporting parts 81 and 83 support the second wiring film WF2. A second adhesive part 77 included in the second wiring film WF2 is adhered to the second supporting parts 81 and 83. The second supporting parts 81 and 83 may be triangular as illustrated in
Referring to
The wiring film WF and the board 10 are aligned so that first bumps 33a and 35a of the wiring film WF respectively correspond to the first pad electrodes 15 and 25. Subsequently, heat and pressure are applied so that the first bumps 33a and 35a are respectively electrically connected to the first pad electrodes 15 and 25.
A second semiconductor chip 60 including second chip pad electrodes 65 is positioned to be flipped on the wiring film WF. The second semiconductor chip 60 and the board 10 are aligned so that the second chip pad electrodes 65 respectively correspond to second bumps 35b positioned in the middle portion the wiring film WF. Subsequently, heat and pressure are applied so that the second chip pad electrodes 65 are respectively electrically connected to the second bumps 35b. Additionally, the second adhesive 39 formed on the second surface of the wiring film WF may be used to adhere the second semiconductor chip 60 to the package.
Among the second bumps 33b and 35b of the wiring film WF, the second bumps 33b positioned at outside portions of the wiring film WF are connected to the second board pad electrodes 55 by conductive pins P.
Subsequently, a molding layer 90 is formed on the board 10, to cover the second semiconductor chip 60 and the wiring film WF. The molding layer 90 contacts the second adhesive layer 39.
Referring to
A semiconductor chip 20 is positioned under the board 10 on a second surface of the board that is opposite to the first surface of the board 10. The semiconductor chip 20 includes chip pad electrodes 25 in its middle part. The chip pad electrodes 25 are exposed by the through-hole 10a.
The wiring film WF described with reference to
As a result, a board on chip (BOC) package is realized, using the wiring film WF including the wires 32.
In accordance with the present invention as described above, the wiring film including wires is used to electrically couple the board pad electrodes to the chip pad electrodes, thereby enabling a semiconductor package to be thin because there is no problem relating to the loop height, unlike the wire bonding method. Additionally, the manufacturing process is simplified over a flip chip method because no redistribution layer is needed to redistribute wires on the board or semiconductor chip, which also reduces the manufacturing process costs. Furthermore, the wiring film includes the adhesive layer on the bumps, thereby requiring no additional adhesive layers between the wiring film and the board or between the wiring film and the semiconductor chip. The adhesive layer is positioned at both sides of the bumps, thereby maintaining the electrical connection between the bumps and the pad electrodes even if the package is bent; thereby improving the reliability of the package.
While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the present invention as defined by the following claims.
Number | Date | Country | Kind |
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2006-0111226 | Nov 2006 | KR | national |