Active solid-state devices (e.g. – transistors – solid-state diode – Housing or package
Reexamination Certificate
2001-10-29
2003-01-14
Zarabian, Amir (Department: 2824)
Active solid-state devices (e.g., transistors, solid-state diode
Housing or package
C257S707000, C257S784000, C438S110000
Reexamination Certificate
active
06507096
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to assembly of a semiconductor package, and more particularly, to a tape having implantable conductive lands which is substituted for a rigid substrate during processes for manufacturing a semiconductor package such as a ball grid array (BGA) type package, and a method for manufacturing the same.
2. Description of the Related Art
Recently, electronic products such as personal computers, cellular phones and camcorders become smaller in size and larger in processing capacity. Accordingly, a semiconductor package which is small in size, large in capacity and compliant with a fast processing speed is fully required. Therefore, semiconductor packages have been transformed from an insertional mounting type including a dual in-line (DIP) package into a surface mounting type including a thin small out-line package (TSOP), a thin quad flat package (TQFP) and a ball grid array (BGA).
The BGA, among the surface mounting types, has attracted considerable attention since it allows the size and the weight of a semiconductor package to be greatly reduced and relatively high quality and reliability to be achieved among chip scale packages (CSPs).
Recently, most semiconductor manufacturing companies have developed CSPs and published developed CSPs by unique names. However, the structures of the CSPs are very similar to one another. A BGA type package is a sort of CSP. Every conventional BGA package uses a rigid substrate formed of, for example, polyimide, bismaleimide triazine (BT) resin or FR-4, instead of using a lead frames, as the body of a semiconductor package. Here, the FR-4 is a resin produced by hardening polymer referred to as dicyandiamide, generated as an intermediate of a melamine compound.
In the rigid substrate, circuit patterns are organically patterned on the front and rear surfaces of an insulation substrate such as polyimide. The circuit patterns are firmly stuck to the insulation substrate with a phenol-based two-side adhesive having an excellent adhesive strength, or a polyimide-based one-side adhesive. The rigid substrate has via-holes formed by piercing the insulation substrate for the interconnection between the circuit patterns, and also includes a solder mask formed of an insulation material for facilitating wire bonding, attachment of external connecting terminals and protection from external damage. Typical BGA packages use solder balls or solder bumps as external connecting terminals, instead of using leads.
Such a rigid substrate remains within a semiconductor package as a part thereof after completion of assembly of the semiconductor package, so it is an obstacle in minimizing the thickness of the semiconductor package. Once in a while, a rigid substrate is eliminated in assembling an improved semiconductor package among the CSPs. However, this case has many difficulties in performing wire bonding, encapsulation and attachment of external connecting terminals.
FIG. 1
is a sectional view of a typical BGA package using a rigid substrate instead of a lead frame. The structure of a conventional BGA package will be described focusing on the manufacturing processes thereof.
Referring to
FIG. 1
, a wafer is cut into individual chips in a sawing process, and thus a chip
2
is prepared for a BGA package. The chip
2
is bonded to a rigid substrate
10
with an epoxy
4
in a die attach process. Bond pads (not shown) of the chip
2
are connected to bond fingers on the rigid substrate
10
through gold wires
6
in a wire bonding process.
Here, circuit patterns
12
are organically formed on the rigid substrate
10
. The circuit patterns
12
formed on the front surface of the rigid substrate
10
are connected to circuit patterns such as solder ball pads
20
formed on the rear surface of the rigid substrate
10
through via-holes
16
. Solder masks
14
and
14
′ for protecting the circuit patterns
12
and for facilitating the attachment of solder balls, i.e., external connecting terminals, are formed on the front and rear surfaces, respectively, of the rigid substrate
10
. An insulation substrate
18
constituting the inner portion of the rigid substrate
10
is formed of a BT resin or a plastic resin such as polyimide.
Subsequently, encapsulation for protecting the chip
2
and gold wires
6
provided on the front surface of the rigid substrate
19
is performed using an epoxy mold compound
8
. Then, solder balls
22
which are external connecting terminals are attached to the solder pads
20
on the bottom of the rigid substrate
10
. Finally, a strip of BGA packages is cut into individual BGA packages in a singluation process.
However, the rigid substrate used in a semiconductor packaging process according to the conventional technology has the following problems.
Firstly, intermediate connectors such as the circuit patterns
12
and
20
formed on the top and bottom of the rigid substrate
10
and via-holes
16
provided between the chip
2
and the external connecting terminals
22
degrade the electrical performance of a BGA package.
Secondarily, the insulation substrate
18
constituting the rigid substrate
10
remains within a BGA package after the completion of assembly of the BGA package, which limits the reduction of the thickness of a semiconductor package. In other words, there is a limitation in reducing the thickness of a semiconductor package.
Thirdly, since a process for forming the solder masks
14
and
14
′ is required to ensure the insulation between the circuit patterns
12
, the manufacturing is complicated.
Finally, the rigid substrate
10
is very elaborate, so it is very difficult to manufacture it and its price is very high. Therefore, the cost for assembling a BGA package is high.
SUMMARY OF THE INVENTION
To solve the above problems, it is an object of the present invention to provide a tape having implantable conductive lands, which can be used instead of a rigid substrate during a semiconductor packaging process and does not remain within a semiconductor package after the assembly of the semiconductor package.
It is another object of the present invention to provide a method for manufacturing the tape having implantable conductive lands for a semiconductor packaging process.
Accordingly, to achieve the first object of the invention, there is provided a tape for a semiconductor packaging process, including a tape film which can be detached from a semiconductor package after an encapsulation process and serves as a lead frame or a substrate until the encapsulation process is completed, in manufacturing the semiconductor package; and implantable conductive lands adhering to the tape film and each having a first surface and a second surface facing each other, wherein the first surface is attached to the tape film and connected to an external connecting terminal of the semiconductor package, and the second surface adheres to an epoxy mold compound, and wire bonding is performed on the second surface.
The tape film includes a tape body in a lower portion and an adhesive layer formed on the tape body. A surface treatment layer is preferably formed on the second surface of each implantable conductive land.
The tape film is formed of a material which does not chemically react with other materials and is not transformed by heat and pressure during the manufacture of the semiconductor package. The tape film may be formed of polymer, paper, metal or a compound including at least one of them.
The adhesive layer may be formed of an adhesive such as a silicone-resin based adhesive facilitating detachment of the tape film from the implantable conductive lands.
The implantable conductive lands are preferably formed of copper or an alloy including copper, and the preferred surface treatment layer is a material layer allowing wire bonding.
To achieve the second object of the invention, there is provided a method for manufacturing a tape having implantable conductive lands for a semiconductor packaging process. The method includes the steps of preparing a ta
Kostat Semiconductor Co., Ltd.
Rothwell Figg Ernst & Manbeck
Wilson Christian D.
Zarabian Amir
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