Electricity: conductors and insulators – Conduits – cables or conductors – Preformed panel circuit arrangement
Reexamination Certificate
2000-03-30
2002-09-24
Cuneo, Kamand (Department: 2841)
Electricity: conductors and insulators
Conduits, cables or conductors
Preformed panel circuit arrangement
C174S261000, C257S783000
Reexamination Certificate
active
06455786
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a wiring board used for manufacturing a semiconductor device of substantially the same size. The present invention also relates to a method of manufacturing the wiring board and a semiconductor device into which the wiring board is incorporated.
DESCRIPTION OF THE BACKGROUND ART
In a chip-size package, the size of which is substantially the same as that of the semiconductor to be incorporated into the package, there is provided an interposer between the semiconductor element and the external connecting terminals such as solder balls. The interposer is provided with wiring for electrically connecting the electrode of the semiconductor element with the external connecting terminals. This interposer is made of flexible material, so that the thermal stress generated by a difference between the coefficient of thermal expansion of the package and that of a mounting board can be reduced.
FIG. 12
is a view showing an example of the conventional BGA (ball grid array) type chip-size package. This semiconductor device is composed in such a manner that a wiring pattern film
14
adheres onto an electrode forming face of a semiconductor element
10
via an elastomer layer
12
. The wiring pattern film
14
is supported by an electrically insulating layer
15
, and a wiring pattern
16
is formed on the wiring pattern film
14
. At one end of the wiring pattern
16
, there is provided a lead
20
connected with the electrode
18
of the semiconductor element
10
, and at the other end of the wiring pattern
16
, there is provided a land
24
which is a part of wiring pattern
16
that is immediately adjacent to, below, and connected with the external connecting terminal
22
. In this product, both the elastomer layer
12
and the wiring pattern film
14
become an interposer.
The lead
20
and the electrode
18
are individually connected with each other by the method of lead bonding. The lead
20
is formed crossing a window
26
formed on the wiring pattern film
14
. Therefore, the lead
20
is connected with the electrode
18
in the process of lead bonding in such a manner that the lead
20
is cut off by a bonding tool through the window
26
.
However, it is not necessarily easy to bond the lead
20
to the electrode
18
with high accuracy by the method of lead bonding. Further, the working efficiency of lead bonding is not necessarily high. In order to overcome the above problems, it is possible to use the method of wire bonding, the working efficiency of which is high, for connecting the wiring pattern
16
with the electrode
18
.
However, when wire bonding is conducted on the wiring pattern film
14
supported by the above flexible elastomer layer
12
, it is impossible to perform the bonding with high accuracy. The reason for this is as follows. Since the elastomer layer
12
is made of flexible material so as to reduce thermal stress, the pushing force exerted by the bonding tool does not act on the bonding section effectively. Therefore, the bonding wire cannot be assuredly connected.
On the other hand, when the wiring pattern film
14
is made of material the elastic modulus of which is high, instead of the flexible elastomer layer
12
, so that the wire bonding property of the wiring pattern
16
can be enhanced, the following problems may be encountered. When the semiconductor device is mounted on a mounting board, thermal stress generated between the mounting board and the semiconductor element
10
acts directly on the external connecting terminals
22
. Therefore, an excessively high intensity of stress acts between the external connecting terminal
22
and the mounting board and also between the external connecting terminal
22
and the semiconductor element
10
, which could cause of a defective connection.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a semiconductor device in which the electrode of the semiconductor element and the external connecting terminal can be assuredly connected with each other by the method of wire bonding in a semiconductor device including an interposer functioning as a wiring board arranged between the semiconductor element and the external connecting terminal. It is another object of the present invention to provide a wiring board suitably for use in manufacturing the semiconductor device. It is still another object of the present invention to provide a method of manufacturing the semiconductor device.
In order to realize the above objects, the present invention provides a wiring board comprising: a first face joined to an electrode forming face of a semiconductor element; and a second face on the opposite side of the first face, a wiring pattern being formed on the second face, a land joined to an external connecting terminal being formed at one end of the wiring pattern, a wire bonding section connected with a bonding wire being formed at the other end of the wiring pattern, wherein the land is supported by a buffer layer for reducing the thermal stress generated when the semiconductor element to which the wiring board is attached is mounted via the external connecting terminals, and the wire bonding section is supported by a bonding support layer having an elastic modulus capable of allowing wire bonding.
The buffer layer is made of material the Young's modulus of which is not more than 1 GPa at 30° C., and the bonding layer is made of material the Young's modulus of which is not less than 4 GPa at room temperature.
A plurality of wire bonding sections are arranged in a peripheral section of the second face, and a plurality of lands are arranged inside the region in which the wire bonding sections are arranged. Alternatively, an opening penetrating from the first face to the second face is formed, a plurality of wire bonding sections are arranged in a peripheral section of the opening on the second face, and a plurality of lands are arranged outside the region in which the wire bonding sections are arranged.
The buffer layer and the bonding support layer are supported by a base support layer the elastic modulus of which is the same as that of the bonding support layer, a side of the base support layer composes the first face, and sides of the buffer layer and the bonding support layer compose the second face.
A plane configuration of a wiring pattern formed on the second face is formed into a curve.
The present invention provides a method of manufacturing a wiring board having a first face joined to an electrode forming face of a semiconductor element and also having a second face on the opposite side of the first face, a wiring pattern being formed on the second face, a land joined to an external connecting terminal being formed at one end of the wiring pattern, a wire bonding section connected with a bonding wire being formed at the other end of the wiring pattern, the method of manufacturing the wiring board comprising the steps of: forming a support sheet made of material the elastic modulus of which is so high that it can support bonding in the process of wire bonding, the support sheet partitioning cavities when a partitioning section which becomes a bonding support layer is arranged on one of the faces of the support sheet, forming a buffer layer when cavities are filled with adhesive sheet material by pressing a sheet of metallic foil on a side on which the cavities of the support sheet are formed, via an adhesive sheet made of material capable of reducing the thermal stress caused when the semiconductor element having the wiring board is mounted via the external connecting terminal, making the buffer layer and the bonding support layer adhere onto the sheet of copper foil, and etching the sheet of metallic foil so as to form a wiring pattern on which one end side becomes lands arranged in a region supported by the buffer layer and the other end side becomes a wire bonding section arranged in a region supported by the bonding support layer.
The present invention also provides another method of manufacturing a wiring board having
Horiuchi Michio
Kurihara Takashi
Mizuno Shigeru
Muramatsu Shigetsugu
Alcalá José H.
Cuneo Kamand
Pennie & Edmonds LLP
Shinko Electric Industries Co. Ltd.
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