JP2000077564A - Semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor device which prevents a bare chip IC from being irradiated on its back side with external light and moreover can be manufactured at low cost. SOLUTION: A light-proof film 8 formed of the same material as that of a wiring pattern conductor is formed on the face 3B of a flexible printed wiring board 2 which is positioned on the back side, when a bare chip IC 5 is mounted thereon, in such a manner that the back side of the bare chip IC 5 is covered without going through the intermediary of an adhesive layer. As a result, the bare chip IC is surely prevented from being irradiated on its back side with external light for a long time with reliability.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device in which a bare chip IC is mounted on a flexible printed circuit board, and more particularly to an improvement in a light shielding structure of the bare chip IC.

[0002]

2. Description of the Related Art In a semiconductor device in which a bare chip IC is mounted on a flexible printed wiring board, the flexible printed wiring board is flexible. In addition, since the wiring work of parts can be rationalized, it is applied to a drive device of a liquid crystal display.

First, a conventional semiconductor device of this type will be described with reference to FIG.

A semiconductor device 1 shown in FIG.
It has a base film 2 as a flexible printed wiring board made of an insulating material such as polyester, and a wiring pattern 4 made of a material such as copper foil is formed on a surface 3A of the base film 2 by plating or etching. Is formed.

On the wiring pattern 4, a bare chip IC 5 and other chip components (not shown) are mounted. Further, a protective film 6 made of a resist material is laminated on the wiring pattern 4 so as to protect the wiring pattern 4.

Meanwhile, the bare chip IC 5 has been pointed out with a problem of an electrical malfunction such that an operation voltage is changed by an incident light from the outside, and an operation failure is caused or the operation is stopped. Heretofore, light shielding for the bare chip IC 5 has been conventionally performed.

The semiconductor device 1 as shown in FIG. 2 has a structure in which external light from the back surface 3B of the base film 2, which is the back of the side on which the bare chip IC 5 is mounted, irradiates the bare chip IC 5. Therefore, it is necessary to provide a structure for blocking external light from the back surface 3B side of the base film 2.

For this reason, in the conventional semiconductor device 1, a light-shielding tape 7A made of a black polyester film or an aluminum vapor-deposited tape is adhered to the back surface 3B of the base film 2 via an adhesive or an adhesive layer 7B. .

[0009]

However, as described above, if the light-shielding tape 7A made of a black polyester film or an aluminum vapor-deposited tape is adhered to the back surface 3B of the base film 2 to shield the light, high-temperature and high-humidity When such a semiconductor device 1 is used in such a severe environment, there is a problem in reliability that the light-shielding tape 7A is peeled off from the base film 2.

Further, in order to adhere the light-shielding tape 7A to the back surface 3B of the base film 2, it is necessary to add a step of attaching the light-shielding tape 7A to the manufacturing process of the semiconductor device 1.
The increase in the number of steps lowers the workability, and there is also a problem in terms of the manufacturing cost of the semiconductor device 2 due to the increase in the material cost of the dedicated sticking device and the light shielding tape 7A.

In view of the foregoing, it is an object of the present invention to provide a semiconductor device which can reliably prevent the bare chip IC from being irradiated with external light from the back for a long period of time and can be manufactured at low cost.

[0012]

In order to achieve the above object, a semiconductor device according to the present invention is characterized in that the semiconductor device is bonded to the other surface of a flexible printed wiring board which is a back side on which a bare chip IC is mounted. The point is that a light-shielding film made of the same material as the conductor of the wiring pattern is formed so as to cover the back of the bare chip IC without interposing the agent layer. In addition, by adopting such a configuration, since the light shielding film is formed directly on the back surface of the flexible printed wiring board, it is possible to reliably prevent the bare chip IC from being irradiated with external light from the back for a long time. .

A feature of the semiconductor device of the present invention according to claim 2 is that the back surface of the bare chip IC is covered without interposing an adhesive layer on the other surface of the flexible printed circuit board on the side on which the bare chip IC is mounted. As described above, a light-shielding film made of the same material as the conductor of the wiring pattern is formed, and this light-shielding film is covered with a protective film including the outer periphery.
By employing such a configuration, it is possible to reliably prevent the bare chip IC from being irradiated with external light from the back for a longer period of time.

A feature of the semiconductor device according to the third aspect of the present invention is that the protective film covering the surface of the wiring pattern and the protective film covering the light-shielding film are formed to have the same thickness by using materials having the same coefficient of thermal expansion. It is in. And by adopting such a configuration, it is possible to prevent the flexible printed wiring board from warping due to a temperature change.

A feature of the semiconductor device of the present invention according to claim 4 is that the light shielding film is grounded. By adopting such a configuration, the bare chip IC can obtain anti-magnetism and anti-static properties.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of the present invention. In FIG. 2, parts which are the same as or correspond to those in the prior art described above with reference to FIG. .

A semiconductor device 1 shown in FIG. 1 has a base film 2 as a flexible printed circuit board made of an insulating material such as polyimide or polyester, similarly to the above-described conventional device. A wiring pattern 4 made of a material such as a copper foil is formed on the surface 3A by plating or etching.

The bare chip IC 5 and other chip components (not shown) are mounted on the wiring pattern 4. Further, a protective film 6 made of a resist material is laminated on the wiring pattern 4 so as to protect the wiring pattern 4.

The configuration so far is the same as that of the above-described conventional semiconductor device 1.

In the present embodiment, the back of the bare chip IC 5 is coated on the back surface 3B of the base film 2 which is the back of the side on which the bare chip IC 5 is mounted.
A light-shielding film 8 for preventing external light from reaching the bare chip IC 5 via the base film 2 is formed directly without an adhesive layer or an adhesive layer. The light-shielding film 8 is made of a copper foil, similarly to the conductor of the wiring pattern 4 described above, and is formed to have the same thickness in the same process as the wiring pattern 4 by plating or etching.

Further, the light-shielding film 8 and the base film 2 including the outer periphery of the light-shielding film 8 are covered with a protective film 9 made of the same resist material as the protective film 6 for covering the wiring pattern 4. The thickness of the protective film 9 is made equal to the thickness of the protective film 6. The material of the protective film 9 is not necessarily the same as the resist material of the protective film 6, but may be any material having the same coefficient of thermal expansion.

Further, the light-shielding film 8 made of copper having good conductivity is grounded by a ground wire (not shown).

Next, the operation and effect of the embodiment having the above-described configuration will be described.

In the semiconductor device 1A of the present embodiment, the light-shielding film 8 is formed directly on the back surface 3B opposite to the mounted bare chip IC 5 with the base film 2 interposed therebetween.
Irradiation of external light to the bare chip IC 5 can be reliably prevented, and malfunction of the bare chip IC 5 can be reliably prevented.

Further, since the light-shielding film 8 is covered with the protective film 9, even if the semiconductor device 1A is used for a long period of time in a severe environment such as high temperature and high humidity, the light-shielding film 8 is not removed from the base film 2. There is no possibility of peeling,
Irradiation of external light to the bare chip IC 5 can be reliably prevented for a long period of time.

Further, since the protective film 9 has the same coefficient of thermal expansion as the protective film 6 and the same thickness as the protective film 6, the base film 2 warps even when the environmental temperature changes. Therefore, the reliability of the semiconductor device 1A can be ensured.

Further, the back surface 3B of the base film 2
The light shielding film 8 is formed in the same step as the formation of the wiring pattern 4 on the front surface 3A of the base film 2, and the protection film on the back surface 3B of the base film 2 and the light shielding film 8 is formed on the base film 2. Since the wiring pattern 4 is formed in the same step as the formation of the wiring pattern 4 on the surface 3A of the film 2, the manufacturing process is simplified and the manufacturing cost can be reduced as compared with the conventional one.

Further, since the light shielding film 8 is grounded, the bare chip IC 5 can obtain anti-magnetism and anti-static properties.

Here, a more specific example of this embodiment will be described. A bare chip IC 5 is formed on the surface 3A of the polyimide base film 2 having a thickness of 25 to 50 μm.
A light-shielding film 8 made of copper foil having a film thickness of 8 to 18 μm is formed on the back surface 3B opposed to the bare chip IC 5 via the base film 2, and a film thickness of 4 to 15 μm is formed so as to cover the light-shielding film 8. The protective film 9 was laminated with a resist material to form a semiconductor device 1A.

The back surface 3B of the base film 2 is irradiated with light containing a short-wavelength component of 1100 nm or less which affects the optical malfunction of the bare chip IC 5, thereby causing the bare chip IC 5 to emit light.
When the operation of No. 5 was confirmed, no malfunction of the bare chip IC 5 occurred. Also, in a reliability acceleration test in a high-temperature and high-humidity environment, neither deterioration of light-shielding performance nor warpage of the base film 2 occurred.

Note that the present invention is not limited to the above-described embodiment, and various modifications can be made as necessary.

[0032]

As described above, according to the semiconductor device of the present invention, the irradiation of the bare chip IC with the external light from the back portion can be reliably prevented for a long time, and the semiconductor device can be manufactured at a low cost.

That is, the flexible printed wiring board, which is the back of the side on which the bare chip IC is mounted, is made of the same material as the conductor of the wiring pattern so as to cover the back of the bare chip IC without using an adhesive layer. Since the light-shielding film is formed, it is possible to reliably prevent the bare chip IC from being irradiated with external light from the back for a long period of time, and to secure the reliability of the semiconductor device for a long period of time.

The other side of the flexible printed wiring board on the side on which the bare chip IC is mounted is made of the same material as the conductor of the wiring pattern so as to cover the back of the bare chip IC without using an adhesive layer. Since the light-shielding film is formed and the light-shielding film is covered with the protective film including the outer periphery, the irradiation of the bare chip IC with the external light from the back can be reliably prevented for a longer period.

Further, by forming the protective film covering the surface of the wiring pattern and the protective film covering the light-shielding film to have the same thickness using materials having the same thermal expansion coefficient, the warpage of the flexible printed wiring board due to a temperature change can be prevented. Thus, the reliability of the semiconductor device can be ensured.

Further, since the light-shielding film is grounded, the bare chip IC can have anti-magnetism and anti-static properties, and in this respect, the reliability of the semiconductor device can be ensured.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of a semiconductor device according to the present invention.

FIG. 2 is a longitudinal sectional view showing a conventional semiconductor device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 1A Semiconductor device 2 Base film 3A One surface of base film 2 3B The other surface of base film 2 4 Wiring pattern 5 Bare chip IC 6,9 Protective film 7A Light shielding film 7B Adhesive layer (adhesive layer) 8 Light shielding film

Claims (4)

[Claims] 1. A semiconductor device in which a wiring pattern is formed on one surface of a flexible printed wiring board made of an insulating material and a bare chip IC is mounted so as to be connected to the wiring pattern. A semiconductor, wherein a light-shielding film made of the same material as the conductor of the wiring pattern is formed on the other surface of the flexible printed wiring board to cover the back of the bare chip IC without using an adhesive layer. apparatus. 2. A semiconductor in which a wiring pattern is formed on one surface of a flexible printed wiring board made of an insulating material, a bare chip IC is mounted so as to be connected to the wiring pattern, and the surface of the wiring pattern is covered with a protective film. In the device, a material similar to the conductor of the wiring pattern is used to cover the back of the bare chip IC without interposing an adhesive layer on the other surface of the flexible printed wiring board on the side on which the bare chip IC is mounted. A semiconductor device, comprising: forming a light-shielding film, and covering the light-shielding film including a periphery thereof with a protective film. 3. The protective film covering the surface of the wiring pattern and the protective film covering the light-shielding film are formed to have the same thickness by using materials having the same thermal expansion coefficient. Semiconductor device. 4. The semiconductor device according to claim 1, wherein the light-shielding film is grounded.