JP2705263B2 - Method for manufacturing TAB tape carrier - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a TAB for mounting semiconductor elements with high efficiency.
The present invention relates to a tape carrier used in a (Tape Automated Bonding) method and a method of manufacturing the same, and more particularly, to a method of manufacturing a TAB tape carrier having bumps on a surface of a lead portion opposite to a carrier tape.

[Conventional technology]

The TAB method is a method developed to efficiently mount semiconductor elements, and mounts semiconductor elements on a tape carrier. In the TAB tape carrier, for example, as shown in FIG. 6, a flexible insulating film 1 is provided with a device hole 3 for mounting a semiconductor element (not shown) and a feed hole (pilot hole) 4 for alignment and the like. It is formed by punching, a copper foil is adhered to the insulating film 1 with an adhesive, and then a lead portion 2a having a predetermined wiring pattern is formed by photoetching. Generally, the insulating film 1 is an insulating film such as an organic polyimide film having a thickness of 70 to 125 μm and a width of 35 mm (or 70 mm, 140 mm or the like), a glass-reinforced epoxy film, or the like.
Rolled copper foil, electrolytic copper foil or the like having a thickness of 18 to 35 μm is used as the copper foil.

In a process called gang bonding in the TAB method, the inner lead portion of the tape carrier is connected to the microelectrode on the semiconductor element by heating and pressing. For this connection, a projection electrode, a so-called bump, is formed on a part of the aluminum electrode on the surface of the semiconductor element, and this is heated and press-bonded to the inner lead portion of the tape carrier. In this method, a bump is formed at the tip of the inner lead portion. Conventionally, the former was mainly used, but recently the latter has tended to be used.

In order to form a bump at the tip of the inner lead portion of the tape carrier, a method of forming a bump on another suitable substrate, for example, a glass plate by electroplating, and transferring the bump to the inner lead portion of the tape carrier, is used. It is well known as the bump method. Further, a method is known in which bumps are laminated and formed on another appropriate substrate together with inner lead portions, and the bumps are transferred onto an insulating film of a tape carrier.
No. 63-291427. The bump is made of an adhesive metal, for example, gold. In order for the bumps on the inner leads to be sufficiently bonded to the electrodes of the semiconductor element, the bumps need to have a predetermined thickness.

As a method of forming a metal bump on the tip of the inner lead portion without using transfer, a method of applying a solution of a salt of gold or solder to a required portion and forming the bump by thermal decomposition is disclosed in No. 34933.

The bumps described above are provided on the surface of the inner lead portion opposite to the surface to which the carrier tape is attached, and have the advantage of being easier to manufacture than those provided on the attachment surface.

The method of forming a bump on a semiconductor element has disadvantages in that not only damage due to plating of the element and short-circuiting between terminals occur, but also the process for forming the bump becomes complicated and the cost of the semiconductor element increases. For this reason, recently, there has been a tendency to frequently use a method of forming a bump at the tip of the inner lead portion of the tape carrier as described above.

[Problems to be solved by the invention]

However, the so-called transfer bump method for forming a bump at the tip of the inner lead portion of the tape carrier is performed in two steps, that is, forming a bump on another substrate and transferring the bump onto a tape carrier. This is a major problem in positional accuracy, and an inner lead with a conductor pitch P (FIG. 6) of 150 μm or less could not be realized. As a method for improving this, the method of JP-A-63-291427 has been proposed, but a concave portion is formed by etching or the like in another conductive support, and the like.
This requires a complicated process of forming a bump portion by electroplating and transferring the bump portion onto a tape carrier via a temporary support. Further, since the bumps having a predetermined thickness are entirely formed of gold, the material cost is high.

The method described in the above-mentioned JP-A-63-34933 has an advantage of not using transfer.However, in order to form a bump having a sufficient thickness by heat decomposition of gold or solder salt, high temperature and long time are required. Processing required. High-temperature processing causes poor insulation between leads.

Also, TAB to provide a bump on the surface opposite to the attaching surface
In the tape carrier for use, since the semiconductor element is located on the opposite side of the device hole, if the inner lead is deformed by the weight of the bump, the bonding operation becomes difficult.

Therefore, an object of the present invention is to provide a miniaturized bump having a predetermined thickness which prevents deformation of the inner lead and provides sufficient bonding without using a transfer requiring a complicated process. An object of the present invention is to provide a method for manufacturing a TAB tape carrier having an inner lead portion (for example, a pitch of 150 μm or less).

Another object of the present invention is that the material and processing cost for providing the bumps is low, and high temperature processing is not used.
An object of the present invention is to provide a method for manufacturing a TAB tape carrier in which a bump having a sufficient thickness is formed at the tip of an inner lead portion.

[Means for solving the problem]

According to the present invention, in order to achieve the above object, a TAB tape provided with a bump on a surface opposite to a surface to be attached to a carrier tape, at a tip of an inner lead portion made of copper or copper alloy foil In the method of manufacturing the carrier, the thickness of the copper or copper alloy foil attached on the carrier tape,
Forming a spot-shaped first plating layer of copper or copper alloy having a thickness of 10 to 50 μm, and forming a lead pattern having a thickness of 0.1 to 5.0 μm on the foil including the spot-shaped first plating layer; A method for producing a TAB tape carrier is provided, wherein a second plating layer of gold or palladium is formed, and unnecessary portions of the foil are removed using the second plating layer as a mask.

And the manufacturing method of the TAB tape carrier provided with a bump at the tip of the inner lead portion according to the present invention,
It comprises the following steps.

(1) Formation of copper or copper alloy foil (2) Step of forming a copper or copper alloy plating layer having a thickness of 10 to 50 μm at a position corresponding to the tip of the inner lead portion (3) Copper or copper alloy plating 0.1 to 5.0 on the layer
Step of coating with a gold or palladium plating layer having a μm lead pattern shape (4) Step of etching foil using gold or palladium plating layer as a mask The details of each step will be described below.

(1) Formation of Copper or Copper Alloy Foil Generally, copper or copper alloy foil serving as an inner lead portion of a TAB tape carrier is connected to an insulating film of polyimide or the like via an adhesive. It can be performed using known materials and methods. All or a part of the pattern may be formed on the copper or copper alloy foil by etching before forming the bump, but it is preferable to form the pattern after forming the bump as described later.

(2) 10 to 50μ thickness at the tip of the inner lead
Step of Forming Copper or Copper Alloy Plating Layer of Copper or Copper Alloy Foil is covered with a mask such as rubber, leaving a position corresponding to the tip of the inner lead portion of the copper or copper alloy foil, that is, a bump forming portion. Apply alloy plating. The thickness of the copper or copper alloy plating is selected from the range of 10 to 50 μm. The thickness of the plating is determined by the thickness of the copper foil in the lead portion, the interval between the lead portions, the type of semiconductor element manufactured by the tape carrier, and the like. For example, a range of 20 to 30 μm for a copper foil having a thickness of 35 μm and a range of 10 to 20 μm for a copper foil having a thickness of 18 μm are generally suitable. At a thickness of 10 μm or less, the effect of pressurization when coupling with a semiconductor element is reduced. If the thickness exceeds 50 μm, the tip of the inner lead becomes heavier, so that the lead is liable to be deformed. Further, when the semiconductor element is joined by pressing, the bump is inclined, and the joining becomes worse. Although electroless plating may be used for plating, electroplating is preferred.

(3) 0.1 to 5.0 thickness on the copper or copper alloy plating layer
Step of coating with a gold or palladium plating layer having the shape of a μm lead pattern After copper or copper alloy plating, the mask is removed, and through a photoresist having an opening formed in advance by applying a resist ink on a foil. , Thickness 0.1 ~ 5.0
Apply gold or palladium plating of μm. Naturally, the bump forming part is plated with gold or palladium.

(4) Step of forming the inner lead by removing the copper or copper alloy foil other than the inner lead portion by etching after forming the bump, removing the photoresist layer used in the plating step of (3) above, and removing the gold. Or use the palladium plating layer as a mask,
An inner lead portion is formed on the carrier film by etching according to a predetermined pattern (pattern of the opening).

[Action]

In the present invention, a spot-like copper or copper alloy plating layer having a thickness of 10 to 50 μm is formed on a copper or copper alloy foil stuck on a carrier tape, and a further thickness of 0.1 μm is formed on the layer. To 5.0 μm gold or palladium plating layer to form bumps.
It has a thickness of 10 μm to 55 μm and is configured to prevent deformation of the inner leads. Moreover, since the surface is made of gold or palladium, it can be easily joined to the semiconductor element by applying pressure.

Since gold or palladium only occupies a thickness of 0.1-5.0 μm, the cost of the material required for bump formation is greatly reduced. Copper or copper alloy and gold or palladium plating are all around 30 ° C, even at high temperatures
Since the heat treatment is performed at a temperature of about 100 ° C., the insulation between the lead portions does not deteriorate.

[Example 1] A bump was formed at a required portion on a rolled copper foil having a thickness of 125 µm and a width of 35 mm, which was bonded to a 35-mm-wide polyimide insulating film via an epoxy adhesive, and a predetermined pattern was formed. The inner lead portion was formed. Details are as follows.

As shown in FIG. 1, an inner lead 2a (tip 2b) on the surface of a copper foil adhered on an insulating film (not shown)
) Was covered with a photoresist 5 and covered with a rubber mask 6 having an opening 6a at the tip 2b of the inner lead, and copper plating with a thickness of 20 μm was performed on the tip 2b from the opening 6a. The rubber mask 6 was removed, and gold plating with a thickness of 5 μm was performed on the copper foil and the copper plating using the opening of the resist 5. The carrier film in this state is shown in FIG.
FIG. 2 shows an enlarged cross-sectional view along X. As shown in FIG. 2, the insulating film 1 is covered with the copper foil 2 including the portion of the device all 3, and a copper plating layer 22 and a gold plating layer 23 are formed at positions corresponding to the tips of the inner leads of the copper foil 2. Is formed. The gold plating layer 23 is formed on the entire portion (2a) corresponding to the resist opening of the copper foil 2 including the bump portion. The portion of the copper foil 2 other than the resist opening is covered with the photoresist 5 and this portion does not have the gold plating layer 23.

After the gold plating, the photoresist 5 was peeled off, and the copper foil 2 was etched with a conventional ferric chloride etching solution (or a cupric chloride etching solution) using the gold plating layer 23 as a mask. Thus, the inner lead portion 2a having a predetermined pattern was formed. At the tip 2b of the inner lead 2a,
A bump 21 composed of a copper plating layer 22 and a gold plating layer 23 is formed. FIG. 3 shows a plan view in this state, and FIG. 4 shows a cross-sectional view. In FIG. 2, the portion covered with only the photoresist 5 is etched with the copper foil 2 excluding the photoresist 5, so that the copper foil 2 does not exist in this portion in FIG.

Terminals (not shown) of the semiconductor element 7 were bonded to the bumps 21 of the TAB tape carrier manufactured as described above, as shown in FIG. TAB produced according to the present invention
The bumps 21 of the tape carrier for practical use could be joined to the terminal portions of the semiconductor element 7 with practically sufficient strength. The semiconductor element 7 has a terminal portion of 100 μm × 100 μm on the surface, and the terminal portion is formed on a 1.5 μm-thick aluminum vapor-deposited film with a thickness of 0.05 μm.
It is coated with a titanium layer of μm and further plated with gold of 2 μm. The terminal portion of the semiconductor element 7 and the bump 21 were diffusion-bonded using a heating device at 500 ° C. After bonding, the semiconductor element 7 is sealed together with the inner lead 2a and the sealing resin 8
Sealed.

Using the method of the present invention, the cost required for gold plating of the TAB tape carrier was about 30 yen per device hole, including the material cost of gold. On the other hand, in the conventional method of forming a bump on a semiconductor element, the formation of a bump by gold plating requires about 110 / element.
It cost a yen.

Example 2 Instead of the gold plating (FIG. 23) in Example 1,
Palladium plating with a thickness of 1.5 μm was performed. As in Example 1, the semiconductor element could be joined to the bump portion with practically sufficient strength.

〔The invention's effect〕

In the TAB tape carrier manufactured according to the present invention, the bump portion provided on the surface opposite to the carrier tape of the inner lead portion has a predetermined thickness, so that the inner lead portion is not deformed, and the bonding operation is facilitated. Become.

Further, according to the present invention, a TAB in which a bump having a sufficient thickness is provided at the tip of an inner lead without using a transfer that easily causes problems in accuracy and yield and requires a complicated process.
Tape carrier can be manufactured. Further, according to the present invention, it is possible to manufacture a TAB tape carrier in which bumps are provided at the tips of micronized (for example, a pitch of 150 μm or less) inner leads.

In the TAB tape carrier manufactured according to the present invention, only the tip portion of the inner lead including the surface of the bump portion is made of gold or palladium, so that the material cost of the noble metal is small. In addition, since the method does not utilize thermal decomposition of a metal compound, high-temperature processing is not required, so that insulation between leads does not deteriorate in a bump forming step.

[Brief description of the drawings]

FIG. 1 is a plan view of a part of a carrier film before copper plating in one embodiment of a method for producing a TAB tape carrier of the present invention, and FIG. 2 is a part of a carrier film after gold plating in the embodiment. FIG. 3 is a plan view of a part of the TAB tape carrier manufactured in the embodiment, FIG. 4 is a cross-sectional view thereof, FIG. 5 is a cross-sectional view after a semiconductor element is bonded to the tape carrier, FIG. Figure 6 shows a general TA
It is a top view which shows the structure of the tape carrier for B. DESCRIPTION OF SYMBOLS 1... Insulating film 2... Copper foil 2 a... Inner lead 2 b... Tip of inner lead 3. Device hole 4. Part 7 Semiconductor element 8 Sealing resin 21 Bump 22 Copper plating layer 23 Gold plating layer

Claims (1)

(57) [Claims] 1. A method for manufacturing a TAB tape carrier, wherein a bump is provided on a surface of a tip of an inner lead portion made of copper or copper alloy foil, the surface being opposite to a surface adhered to a carrier tape. Forming a spot-shaped first plating layer of copper or copper alloy having a thickness of 10 to 50 μm on a copper or copper alloy foil attached to a tape, including the spot-shaped first plating layer; Forming a second plating layer of gold or palladium in the form of a lead pattern having a thickness of 0.1 to 5.0 μm on the foil, and removing unnecessary portions of the foil using the second plating layer as a mask; A method for producing a TAB tape carrier.