JPH0722470A - Tab tape with bump and junction using it - Google Patents

Abstract

PURPOSE: To provide a tab tape with bumps and bonding method using the same, so that the bumps of inner leads do not peel off at a reflow bonding of outer leads. CONSTITUTION: This TAB tape has metal wirings 11 on a dielectric film base 10, vias 12 communicating with the wirings 11 from the opposite base surface to the surface having the wires 11, and inner lead bonding bumps 13 and outer lead bonding terminals at part of the metal wirings 11. The m.p. of the bump 13 is higher than that of a metal 14 for bonding the outer lead-bonding terminals.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a TAB tape with bumps and a joining method using the TAB tape. More specifically, it relates to a bumped TAB tape in which metal wiring provided on a base material made of a dielectric film is connected through a via hole provided through the base material, and a bonding method using the TAB tape.

In recent years, TAB (Tape Automated) capable of high-density connection due to high integration of IC chips
Bonding) has attracted attention assembling semiconductor devices. In this TAB method, a copper foil is adhered to a film such as polyimide or polyester, which is etched by photolithography to form a metal wiring, and the metal wiring is used to electrically connect an IC chip to a printed wiring board or package. It is designed to be connectable.

[0003]

2. Description of the Related Art One example of a conventional TAB tape is shown in FIG. In the figure, 1 is a film-shaped base material having a perforation 2, and a metal wiring 3 is provided on the surface thereof. One end of this metal wiring serves as an inner lead 3a for connecting to an electrode of the IC chip, and the other end serves as an outer lead 3b for connecting to a terminal of a printed wiring board or a package.

Then, as shown in FIG. 1B, bumps 4 are provided on the inner leads 3a, and the outer leads 3 are formed.
A metal 5 for joining for reflow connection to the terminals of the printed wiring board or the package is provided on b. In FIG. 4, 6 is a window for mounting an IC chip, and 7 is a window for connecting outer leads.

As another example of the TAB tape, as shown in FIG. 5, from the surface of the base material 1 opposite to the surface on which the metal wiring 3 is provided, for the purpose of preventing the possibility of short-circuiting even at a narrow pitch. There is also one in which a via hole 8 communicating with the metal wiring 3 is provided and the bump 4 is provided in the via hole 8.

The above-mentioned TAB tape has been widely used for assembling semiconductor devices because it has the following advantages. a: It is possible to perform a performance test of the IC chip in advance before the final assembling of the IC chip. b: The degree of freedom in connecting the IC chip to the substrate or the like is improved. (A TAB tape can be bent and mounted on the back side of a liquid crystal panel, etc.) c: High-density mounting is possible. d: The reflow method can be easily used as a method of connecting to a substrate or the like.

[0007]

In the above-mentioned conventional TAB tape, since the bumps for the inner lead bonding and the bonding metal for the terminals for the outer lead bonding are generally the same metal, for example, solder is generally used, There is such a problem. a: Since the bumps for joining the inner leads and the joining metal of the terminals for joining the outer leads have the same melting point, the joined portion of the inner leads previously joined may be peeled off during the outer lead connection. b: In particular, in the reflow method in which the entire TAB tape is uniformly heated in a short time, there is a risk of peeling off the joint portion of the inner lead.

Therefore, in order to solve this problem, a TAB tape with bumps has been partially implemented in which the bumps for joining inner leads and the joining metal of the terminals for joining outer leads are different metals. However, in order to use dissimilar metals, it is necessary to plate the bumps of the inner leads and the metal for joining the outer leads with different metals, and when plating one, it is necessary to go through a complicated process such as masking the other. In addition to the increase in cost, the problem of contamination by the plating solution and the like is caused, which causes malfunction of the IC chip.

In view of the above-mentioned conventional problems, the present invention prevents the joint portion between the inner lead and the IC chip, which have been joined in advance, from being peeled off by the heating when the outer lead is joined to the substrate or the like, and is contaminated by plating. An attempt is made to realize a TAB tape with bumps and a bonding method using the same.

[0010]

TAs with bumps according to the present invention
In the B tape, a plurality of metal wirings are provided on a base material made of a dielectric film, and a via hole communicating with the metal wiring is provided from a surface of the base material opposite to a surface on which the metal wirings are provided. In a TAB tape with bumps in which a bump for inner lead bonding and a terminal for outer lead bonding are provided in a part of the metal wiring, the melting point of the bump for inner lead bonding is equal to that of the metal for bonding the outer lead bonding terminal. It is characterized by being higher than the melting point.

In addition to this, the melting point of the bumps for joining the inner leads is at least 50 ° C. higher than the melting point of the joining metal of the terminals for joining the outer leads. Further, the bumps for joining the inner leads are made of solder and have a ball shape. The via hole is funnel-shaped.

Further, in the joining method using the TAB tape with bumps of the present invention, when the outer leads of the TAB tape with bumps are joined to a substrate or the like, they are joined by a reflow method.

By adopting this configuration, the joint portion between the inner lead and the IC chip, which have been jointed in advance, is prevented from being peeled off by the heating at the time of joining the outer lead to the substrate or the like, and the bumps are reduced in pollution due to plating. An attached TAB tape and a joining method using the same can be obtained.

[0014]

[Function] A bump for inner lead bonding, which is bonded to a metal wiring provided on a base material made of a dielectric film,
In a TAB tape with bumps provided with a bonding metal for outer lead bonding terminals, first bumps for inner lead bonding are bonded to electrodes of an IC chip, and then bonding metal for outer lead bonding terminals is printed on a printed board. Or, when bonding to a pad of a substrate such as a package, in the present invention, since the melting point of the bump for inner lead bonding is set higher than the melting point of the bonding metal of the terminal for outer lead bonding, the temperature at the time of outer lead bonding is different. The inner lead bumps do not melt. Therefore, the bump does not peel off from the electrode of the IC chip.

[0015]

EXAMPLE FIG. 1 shows an example of a TAB tape with bumps according to the present invention. In the figure, 10 is a base material made of a dielectric film, and a metal wiring 11 is provided on one surface thereof. Then, the inner lead 10a of the base material 10
A via hole 12 reaching the metal wiring 11 is provided from the other surface of the portion to be the bump.
3 is provided. In addition, the bonding metal 14 is provided on the metal wiring 11 in the portion which becomes the outer lead bonding terminal 10b.
Is provided.

A resin film made of polyimide, polyester, polyphenylene sulphite or the like is used as the dielectric film of the base material 10, and its thickness is 15 μm.
If it is less than m, the strength is insufficient, and if it exceeds 125 μm, it is difficult to reduce the thickness. Therefore, the range of 15 to 125 μm is preferable.

The metal wiring 11 may be copper, aluminum, gold or an alloy thereof, or copper or the like plated with gold or silver. In addition, it is preferable that metal wiring is formed on the base material by performing flash plating and then plating with copper or the like, but this is because there is no adhesive layer, via holes can be easily formed, and impurity ions can be formed. This is because there are few cases and thinning is possible. In addition, it is also possible to stack a solution-form polyimide resin on the surface of a copper foil or the like to form a composite having no adhesive layer, and then provide a metal wiring by using an ordinary etching technique.

The metal wiring formed by etching the copper foil adhered to the base material using an adhesive does not etch the adhesive when the via hole is formed. It is necessary not to use because it requires a complicated process.

The via hole 12 is a metal wiring 1
This means a through hole that communicates with the metal wiring 11 from the surface of the base material opposite to the surface on which the 1 is formed, and the shape of the hole may be circular or rectangular. If the size of the hole is less than 20 μm, it is difficult to manufacture, and the metal for forming bumps easily flows out, which may cause a short circuit. Therefore, the minimum diameter is preferably 20 μm or more. Further, the shape of the via hole 12 is preferably funnel-shaped so as to open on the surface opposite to the metal wiring surface as shown in FIG. This is because the funnel shape can increase the contact area with the terminals of the IC chip.

The bump 13 is preferably a metal having a melting point at least higher than that of the bonding metal 14 of the outer lead bonding terminal 10b, preferably 50 ° C. or higher. Ordinary outer lead joining terminal joining metal 1
Since solder is used for reflow in No. 4, solder or metal or alloy such as gold or silver having a melting point higher than this can be used in the present invention, but the selection is for joining outer lead joining terminals. It is desirable to determine in consideration of the melting point of the metal 14. Further, the melting point or the thermal diffusion temperature of the bump 13 is preferably a temperature at which the IC chip, the TAB tape or the like is not thermally damaged, and specifically, 350 ° C. or less is desirable.

The shape of the metal used for the bump 13 is
A ball shape is preferable because it can conduct and melt heat uniformly, prevent the occurrence of short circuit, and easily fill the via hole. The size of the ball is the via hole 12.
If the volume is less than 50%, it becomes difficult to connect with the IC chip. On the other hand, if it exceeds 200%, the molten metal may flow out to the outside to cause a short circuit.
Is preferred. The ball-shaped bump may be a single ball or a combination of a plurality of balls.

Further, after the ball-shaped metal is filled in the via hole 12, it may be partially heated or pressure-bonded so as to be adhered to the metal wiring 11 in order to hold it on the TAB tape, and other low molecular weight binders such as alcohol. May be applied on the bumps.

In this embodiment having such a structure, since the plating method is not used for forming the bumps for joining the inner leads, there is no contamination by the plating solution. Further, since the melting temperature of the bump is set higher than the melting point of the joining metal of the outer lead joining terminal, when the outer lead is joined to the substrate or the like, the bump does not come off from the IC chip and the TAB tape at that temperature. .

FIG. 3 is a diagram for explaining a method of joining the TAB tape with bumps according to the present invention. Bumped TA of the present invention
To use the B tape, the bumps 13 of the TAB tape 15 with bumps are first aligned with the electrodes 17 of the IC chip 16 as shown in FIG. Next, as shown in FIG. 3B, the TAB tape 15 with bumps is heated using a bonding tool 18 to bond the bumps 13 to the electrodes 17 of the IC chip 16. In this case, when the bump 13 is a simple substance or alloy of a low melting point metal such as solder, it is melted and joined, and when the bump 13 is a simple substance or alloy of high melting point metal such as gold copper, it is joined by diffusion.

Next, the bumped TAB tape 15 with the IC chips bonded is turned over, and as shown in FIG. 3C, the bonding metal 14 of the outer lead bonding terminal is bonded to a substrate 19 such as a printed board. It is positioned and mounted on the pad 20 for use, and the whole is heated using a heating furnace or the like, and the bonding metal 14 of the outer lead bonding terminal is reflowed and bonded to the pad 20. In this case, since the melting point (or diffusion temperature) of the bump 13 bonded to the electrode 17 of the IC chip is higher than that of the bonding metal 14 of the outer lead bonding terminal, the bump 13 is not peeled off.

Table 2 shows the test results when the TAB tape with bumps was bonded to the semiconductor chip and the substrate under the conditions shown in Table 1. In Table 2, the chip state is
It is the result of visual inspection and continuity inspection of the peeling of the IC chip from the TAB tape. OK means that there is no abnormality in the visual inspection and continuity inspection. Indicates the case where peeling was visually observed.

[0027]

[Table 1]

[0028]

[Table 2]

From Table 2, Test No. 4 in which the temperature difference between the melting points of the bump and the metal for joining the outer leads is 0 ° and -20 °
It can be seen that the test number 5 of No. 5 is a defective chip state and the other test numbers of 50 ° or more are good.

[0030]

According to the present invention, a metal having a higher melting point than the bonding metal of the outer lead bonding terminal is used for the bump for inner lead bonding, and the bump has a ball shape and is provided on the base material. By heating or crimping partly so as to connect to the metal wiring through the via hole, bumps can be formed without relying on the plating method, so contamination by the plating solution can be prevented, and at the time of reflow bonding to the substrate etc. of the outer lead, It is possible to prevent the bumps from peeling at that temperature, which contributes to the improvement of the quality and yield of the semiconductor device assembly.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a TAB tape with bumps of the present invention.

FIG. 2 is a cross-sectional view showing a via hole in an example of a TAB tape with bumps of the present invention.

FIG. 3 is a diagram for explaining a joining method using the TAB tape with bumps of the present invention.

FIG. 4 is a diagram showing an example of a conventional TAB tape, (a)
Is a plan view and (b) is a cross-sectional view taken along line bb of FIG.

FIG. 5 is a cross-sectional view showing another example of a conventional TAB tape.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Base material 11 ... Metal wiring 12 ... Via hole 13 ... Bump 14 ... Outer lead joining metal

Claims (6)

[Claims] 1. A plurality of metal wirings are provided on a base material made of a dielectric film, and a via hole is provided which leads to the metal wirings from a surface of the base material opposite to a surface on which the metal wirings are provided.
TA with bumps in which bumps for joining inner leads and terminals for joining outer leads are provided on a part of the metal wiring.
In the B tape, the melting point of the bump for the inner lead bonding is higher than the melting point of the bonding metal of the terminal for the outer lead bonding, and the TAB tape with bumps. 2. The bumped TAB tape according to claim 1, wherein the melting point of the bump for the inner lead bonding is at least 50 ° C. higher than the melting point of the bonding metal of the outer lead bonding terminal. . 3. The TAB tape with bumps according to claim 1, wherein the bumps for joining the inner leads are solder. 4. The TAB tape with bumps according to claim 1, wherein the bumps for joining the inner leads are ball-shaped. 5. The TAB tape with bumps according to claim 1, wherein the via hole is funnel-shaped. 6. A method of joining a TAB tape with bumps, wherein the outer lead of the TAB tape with bumps according to claim 1 is joined by a reflow method when it is joined to a substrate or the like.