JPH065662A - Semiconductor device film carrier tape and manufacture thereof - Google Patents

Abstract

PURPOSE:To improve bending-resistant properties of the leads of a film carrier mounted as bent so as to remarkably enhance a semiconductor device in reliability. CONSTITUTION:A lead pattern 20 is formed on a rolled copper foil 3 pasted on an insulating film 1 through the intermediary of adhesive agent, leads on the rolled copper foil 3 surface are partially covered with solder resist as solder protecting masking material, and the leads are subjected to a heat treatment at a temperature of 170 deg.C for one hour to be softened. The temperature of a heat treatment is set to a range of 160 to 200 deg.C depending upon the type of the rolled copper foil 3. The leads are softened by a thermal treatment, whereby bending points 21 of a lead pattern 20 located on slits 7 and 7 are set below 70Hv in Vickers hardness and over 10% in elongation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film carrier tape for a semiconductor device which is required to be bent and mounted, and a method for manufacturing the same, and more particularly, to a film carrier tape having improved resistance to bending during lead bending.

[0002]

2. Description of the Related Art Conventionally, as a film carrier tape for a semiconductor device for joining semiconductor chips, one prepared by coating an epoxy adhesive on a polyimide film and laminating electrolytic copper foil or high-purity rolled copper foil is used. To do. This copper foil is chemically etched to form a lead pattern that constitutes inner leads, outer leads and the like. The method of manufacturing such a film carrier tape for a semiconductor device is as follows.

First, a polyimide film as a flexible insulating film is preliminarily punched by punching a device hole for a semiconductor chip, an outer lead hole of a wiring terminal portion, etc. with an adhesive applied. .
Then, a copper foil is attached to the adhesive surface side of the polyimide film, and heat treatment is performed at a temperature of about 160 ° C. to cure the adhesive.

Next, a photosensitive resist is applied to the surface of the copper foil attached to the film, the lead pattern is baked by exposure and development, and then the lead pattern is formed with an etching solution such as copper chloride. After removing the photosensitive resist, Sn plating with a thickness of about 0.5 μm is applied to the surface of the lead pattern in order to secure inner lead bonding and solder jointability of the outer leads.

Then, the Au bumps provided on the electrodes on the semiconductor chip and the fingers of the Sn-plated inner leads are thermally pressed and bonded. Then, the semiconductor chip and a part of the inner lead are sealed with resin,
Complete the semiconductor device.

[0006]

Generally, there are a rolled copper foil and an electrolytic copper foil as a copper foil to be bonded to a polyimide film, and the rolled copper foil or the electrolytic copper foil has a rigidity of 15% or less in elongation. Uses high hardwood. Particularly in the case of rolled copper foil, the elongation is 5% or less and the Vickers hardness is 10
Hardened foil of 0 Hv or more is used. This is to eliminate problems such as wrinkles occurring when the softening foil is attached to the insulating film and the handling work is deteriorated.

On the other hand, since the characteristic of the film carrier tape is film-like and flexible, there is an example in which the film carrier tape is bent and used even after the completion of the semiconductor device by utilizing the characteristic. However, in the case of the above-described one, when bent, the copper foil forming the lead pattern is hard and has a small elongation as described above, so that the lead pattern may be broken.
In particular, multiple film carriers with semiconductor chips are mounted on equipment or modules at one time, and if even one is defective, the joint will be removed and rejoined, but bending is repeated during this rejoining. Therefore, breakage of the lead is likely to occur. In such a film carrier which is required to be bent and mounted, the bending resistance of the lead pattern is a problem.

Therefore, in order to improve the bending resistance, a TAB of a bending mounting type, for example, for a liquid crystal display is conventionally used.
In order to reduce the stress applied to the bending lead portion, the film carrier tape for punching is provided with the slit 7 at the same time as the formation of the device hole and the like by punching processing on the insulating film portion to be the bending portion. There is. When the slits are provided, cracks and breaks that occur in the leads during bending are surely reduced as compared with the case where the slits are not provided. However, the occurrence of cracks and wire breakage was not completely eliminated, and the defective rate of cracking and wire breakage occurrence in the lead bending resistance test of the slit portion was still high.

The object of the present invention is to eliminate the above-mentioned drawbacks of the prior art and to improve the crease resistance of the leads used in the carrier tape by subjecting the leads to a treatment which is extremely suitable for improving the crease resistance. It is an object of the present invention to provide a film carrier tape for a semiconductor device and a method for manufacturing the same, which can significantly improve the reliability of the semiconductor device.

[0010]

A film carrier tape for a semiconductor device according to the present invention is a film carrier tape for a semiconductor device in which a lead pattern is formed on an insulating film and a bent portion of the lead pattern is formed. It is composed of softened copper foil. As the copper foil, there are rolled copper foil and electrolytic copper foil depending on the material, but there is pure copper foil depending on the composition.

Further, the method for producing a film carrier tape for a semiconductor device of the present invention is a method for producing a carrier tape having a bent portion in which an electrolytic copper foil is attached to an insulating film and a predetermined lead pattern is formed on the electrolytic copper foil. In the method, after the lead pattern is formed, the lead pattern is subjected to a softening treatment for softening the elongation to 10% or more.

The method for producing a film carrier tape for a semiconductor device according to the present invention is a method for producing a carrier tape having a bent portion in which a rolled copper foil is attached to an insulating film and a predetermined lead pattern is formed on the rolled copper foil. In the method, after forming the lead pattern, the lead pattern is subjected to a softening treatment for softening the Vickers hardness to 70 Hv or less and the elongation to 5% or more. The reason why the Vickers hardness is 70 Hv or less is that it can be used to judge that the rolled copper foil has been softened (stretched). That is, in rolled copper foil, Table 1 shows the relationship between elongation and hardness (Hv).
The correlation as shown in is observed.

[0013]

[Table 1]

Since it is difficult to measure the hardness Hv of the electrolytic copper foil, the softening judgment based on the Vickers hardness cannot be used unlike the rolled copper foil.

[0015]

When the lead pattern is softened after the lead pattern is formed, the bending resistance of the lead pattern at the bent portion is significantly improved. Since the softening treatment is performed after the lead pattern is formed, and the softening treatment is not performed before the lead pattern is formed, the copper foil on which the lead pattern is formed is hard and remains rigid. It does not occur and the handling work does not deteriorate.

By the way, the copper foil attached to the insulating film is softened by applying heat treatment thereto, but a high softening temperature is disadvantageous because it damages the insulating film.
In this respect, the OFC is normally required for rolled copper foil because of its requirement for electrical conductivity.
9 (oxygen-free copper) or TPC (tough pitch copper)
High-purity copper with 9.9% Cu is used. These high-purity coppers start to soften and become
The C-based rolled copper foil can reduce the semi-softening temperature to near 150 ° C., which is advantageous for the insulating film used for the carrier tape. Therefore, the rolled pure copper foil is most suitable as a softened copper foil.

On the other hand, a copper alloy containing an additive such as Sn or Zr usually has a semi-softening temperature of more than 300 ° C., and therefore high temperature heating is required to soften the copper alloy foil, and the insulating film It is not preferable because it will damage the.

In order to obtain the characteristics of the electrolytic copper foil,
Semi-softening temperature of 200 because it contains a very small amount of additives
It will exceed ℃. For this reason, the electrolytic copper foil is not as good as the copper alloy foil, but it is not the most suitable as a copper foil that is softened due to higher heat treatment than the rolled copper foil, but it is within the scope of the present invention.

[0019]

Embodiments of the present invention will be described below with reference to FIGS. FIG. 1 shows a plan view of an embodiment of a TAB film carrier for a general LCD driver (liquid crystal display driver) which is mounted by bending, and FIG. 2 shows a sectional view of the TAB film carrier mounted on a liquid crystal module. It is a thing.

An adhesive 2 made of imide and having a thickness of about 25 μm is applied on one side of a flexible insulating film 1 having a film thickness of about 50 to 125 μm such as polyimide. First, the sprocket hole 5, the device hole 6, the outer lead hole 8 and the like are punched in the polyimide film 1 with the adhesive. Simultaneously with this, slits 7 and 7 are also punched in two places to be the bent portions 21 and 21 of the film carrier. Then, a rolled copper foil 3 (OFC-ACE foil) having a thickness of 35 μm is attached by a laminating method.

After bonding, a photosensitive resist is uniformly applied to the surface of the copper foil 3, exposed and developed, and a lead pattern 20 such as an inner lead 10, an outer lead 11 and a fan-out portion 12 is formed by an etching method. To do. Inner leads 10 serving as connection terminals with semiconductor chips are formed with a pitch of about 100 to 180 μm and a width of 30 to 70 μm, and outer leads 11 serving as wiring terminals to a printed circuit board or the like are formed with a pitch of 180 to 400 μm and a width of 90 to 200 μm. To be done. After the lead pattern is formed, a part of the lead surface, that is, the lead of the mask portion at the time of soldering is covered with a solder resist 13 as a mask material for heat protection, and then heat treatment is performed at 170 ° C. × 1 hr. This heat treatment temperature is set to 160 to 200 ° C. according to the type of copper foil 3. This heat treatment softens the OFC-ACE foil, whereby the lead patterns 2 located on the slits 7, 7 are formed.
The bent portion 21 of 0 has a Vickers hardness of 70 Hv or less and an elongation of 5% or more.

Then, the portion where the lead surface is exposed and which is used for the bonding portion is coated with 0.5 μm by electroless Sn plating.
m Sn plating 14 is applied. Thus, the TAB film carrier shown in FIG. 1 is formed and cut at the positions of the outer lead holes 8 and the fan-out portions 12 to obtain one film carrier.

FIG. 2 shows a mounting example of a liquid crystal device using the above film carrier. A semiconductor device (liquid crystal driver) manufactured by mounting the semiconductor chip 15 on a carrier tape is
Using the film carrier, the semiconductor chip 15 on which the Au bumps 16 are formed in advance and the inner lead 10 of the film carrier are Au-Sn eutectic bonded to each other.

The film carrier thus constructed is
As shown in FIG. 2, the outer lead 11 is soldered to the printed circuit board 17, and the LCD panel 18 is soldered to the fan-out portion 12 by a conductive resin. At this time, in order to make the liquid crystal panel 18 as small as possible in appearance, the film carrier with a semiconductor chip is bent by 90 ° using the two slits 7, 7 to make a total of 180 °.
Bend and mount. At this time, since the slit 7 for reducing the bending stress is formed and the copper foil forming the lead pattern is soft and has a large elongation, the lead pattern of the bent portion 21 is not broken. Further, even if there is a case where the mounting is defective and the bending is repeatedly performed by re-bonding, the breakage of the lead is unlikely to occur.

As described above, according to this embodiment, the carrier tape is manufactured in substantially the same steps as the conventional example, but the only difference from the conventional method is the heat treatment step for softening the copper foil after the solder resist. Is only the point where
The mounting method for the CD driver does not change at all. Therefore, the breakage resistance of the leads can be improved without impairing the workability, and the mounting reliability of not only the semiconductor device but also the liquid crystal device can be significantly improved.

In the above embodiment, the case of applying the rolled copper foil has been described, but the present invention is not limited to this and can be applied to the electrolytic copper foil. Rolled copper foil differs from electrolytic copper foil in softening temperature characteristics. Generally, in the case of rolled copper foil,
The raw tape has an elongation of about 1 to 2%, and it is confirmed that the bending resistance is improved by making the elongation of 5% or more. On the other hand, in the case of the electro-deposited copper foil, the elongation in the state of the raw tape is quite good, but the elongation of the raw tape has a large variation of 6 to 13%. From this, when the present invention is applied to the electrolytic copper foil, a heat treatment whose elongation stably exceeds 10% is applied. Table 2 summarizes this.

[0027]

[Table 2]

Further, the copper foil used for manufacturing the carrier tape is a hard material at the beginning, but at the time when it is completed as a carrier tape for a semiconductor device, it suffices that the above-mentioned elongation can be obtained. As described in the examples, it may be applied after the solder resist is applied, but it may be applied after completion of the plated carrier tape or after cutting to form a film carrier, and the heat treatment step may be introduced at any location.

Table 3 shows the experimental results on the relationship between the elongation of the copper foil and the bending resistance. As the folding resistance test, a folding strength test method based on the MIT folding resistance test (JIS P8115) shown in FIG. 3 was used.

[0030]

[Table 3]

The copper foil of the comparative example is a standard product, and the copper foil of the example is a heat-treated product. As shown in Table 3, by improving the elongation of the copper foil regardless of whether it is an electrolytic copper foil or a rolled copper foil, the effect of improving the folding resistance is large, and the film carrier tape for a semiconductor device according to this example was used. It can be expected that the mounting reliability of the liquid crystal device will be significantly improved.

[0032]

(1) According to the film carrier tape for a semiconductor device of the first aspect, since the lead is composed of the softened lead, it is possible to improve the bending resistance at the time of bending the lead, and the semiconductor device. The reliability of can be improved.

(2) According to the method of manufacturing a film carrier tape for a semiconductor device of the second aspect, a lead formed by processing from an electrolytic copper foil has a simple structure in which a treatment step for softening the lead is added. You can improve the property.

(3) According to the method of manufacturing the film carrier tape for a semiconductor device of the third aspect, the bending resistance of the lead processed and formed from the rolled copper foil is simple by adding a treatment step for softening the lead. You can improve the property.

[Brief description of drawings]

FIG. 1 is a plan view showing an example of a pattern of a carrier tape for semiconductors of the present invention.

FIG. 2 is a transverse cross-sectional view showing an embodiment when mounted on a liquid crystal panel using the semiconductor carrier tape of the present invention.

FIG. 3 is an explanatory diagram of a bending resistance test of a copper foil.

[Explanation of symbols]

 1 Insulating Film 2 Adhesive 3 Copper Foil 5 Sprocket Hole 6 Device Hole 7 Slit 8 Outer Lead Hole 9 Inner Lead 10 Outer Lead 11 Outer Lead 12 Fan Out Part 13 Solder Resist 14 Sn Plating 15 Semiconductor Chip 16 Au Bump 17 Printed Circuit Board 18 Liquid crystal panel 19 Liquid crystal 20 Lead (lead pattern) 21 Bent part

Claims (3)

[Claims] 1. A film carrier tape for a semiconductor device having a lead pattern formed on an insulating film and having a bent portion of the lead pattern, wherein the lead is composed of a softened copper foil. Film carrier tape for equipment. 2. A method of manufacturing a carrier tape having a bent portion in which an electrolytic copper foil is attached to an insulating film and a predetermined lead pattern is formed on the electrolytic copper foil, and after the lead pattern is formed, the lead pattern is formed. Grows to 1
A method of manufacturing a film carrier tape for a semiconductor device, which is characterized by being subjected to a softening treatment for softening it to 0% or more. 3. A method for producing a carrier tape having a folded portion in which a rolled copper foil is attached to an insulating film and a predetermined lead pattern is formed on the rolled copper foil, and the lead pattern is formed on the lead tape, and then the lead pattern is formed. A method of manufacturing a film carrier tape for a semiconductor device, wherein the softening treatment is performed to soften the Vickers hardness to 70 Hv or less and the elongation to 5% or more.