JPH11233543A - Forming method for bump and electronic part with bump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic part with bump, which can stably be jointed even if the dispersion of flatness, inclinations and warps exist in a film carrier and a substrate and whose mounting is easy even if a bump is miniaturized by making a pad pitch to be narrow. SOLUTION: A first bump 8a provided on the conductor part of an electronic part such as a semiconductor element 5 and a second bump 8b formed on the first bump are provided. The tip of wire transferred to a capillary is heated/ melted by using a wire bonder for ball bonding and the ball is abutted on the conductor part of the electronic part. The first bump 8a is formed on the conductor part and the second bump 8b is overlapped and formed on the first bump 8a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of forming a bump used when an electronic component such as a semiconductor device is electrically connected to another electronic component such as a substrate, and a semiconductor device having the bump formed thereon. For electronic components such as.

[0002]

2. Description of the Related Art At present, when a semiconductor element such as an IC chip is electrically connected to various substrates or the like, an electrode pad of the semiconductor element and an external electrode are connected by a bonding wire such as a gold wire. The wire bonding method is mainly used.

However, in order to meet the recent demand for smaller and thinner semiconductor devices, it is necessary to provide more elements and circuits in a limited space inside the device. The limitations of the passing wire bonding method are pointed out.

Therefore, as a connection method instead of wire bonding, a method of forming a metal projection (bump) on an electrode pad of a semiconductor element and connecting an external electrode to the bump is known. According to this connection method using bumps, the opposed electrode pads and external electrodes can be directly connected via the bumps without using a boding wire, so that the density of elements and circuits can be increased.

[0005] The semiconductor element having the bumps formed thereon as described above is mounted by pressing the bumps to external electrodes such as various substrates and connecting them under pressure. For example, TAB (Tape
In the case of the Automated Bonding method, it is mounted on a film carrier, and in the case of the flip chip method, it is mounted on a printed circuit board or a glass substrate.

Also, instead of providing bumps on a semiconductor element, bumps are formed on the above-mentioned various substrates, film carriers, flexible printed circuits, or the like, and electrode pads of the semiconductor element are connected to the bumps. .

[0007]

Even with the mounting of semiconductor elements and the like using bumps as described above, stable mounting tends to become difficult with the recent progress of higher density and more pins.

That is, when the flatness of the film carrier or the substrate is uneven, or the inclination or warpage occurs, if the bump height is low, the electrode pad and the entire film carrier or the substrate are required for bonding. Cannot be pressurized by load. For this reason, it is easy for partial bonding failure to occur in many bumps.

Further, the pitch of pads tends to be narrower due to the recent increase in the number of bins, and accordingly, it is necessary to control the bumps to be smaller. However, as the size of the bump is reduced, the space between the electrode pad to be connected and the external electrode becomes smaller, so that mounting with the bump tends to be very difficult.

The present invention has been made in order to solve such a conventional problem, and even if the flatness of a film carrier, a substrate, or the like is varied, or if a tilt or a warp occurs, a partial area of the film carrier or a substrate is generated. An object of the present invention is to provide a bump forming method capable of performing stable bonding without causing a bonding defect, and being able to cope with miniaturization of bumps by narrowing the pad pitch, easily mounting with bumps, and improving yield.

[0011]

In order to achieve the above object, the present invention provides a method for forming a bump used for electrical connection of an electronic component, wherein a first bump is formed on a conductor portion of the electronic component. And forming a second bump on the first bump by stacking the second bump on the first bump.

As an example of the method of forming the bump, a ball bonding wire bonder is used to heat and melt the tip of the wire transferred to the capillary to form a ball, and then lower the capillary to dispose the ball. After the first bump is formed on the conductor by applying a load and an ultrasonic wave to the conductor of the component and applying a load and an ultrasonic wave, the second bump is similarly superimposed on the first bump. Form.

Further, the electronic component with a bump according to the present invention includes a first bump provided on a conductor portion of the electronic component, and a second bump formed on the first bump. It is characterized by the following.

Here, the electronic components include various substrates such as a printed circuit board and a glass substrate, a film carrier, a flexible printed circuit, etc., in addition to the semiconductor element. It is used in a sense that includes those that can form connection bumps.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a second bump is further formed on a normal bump. Therefore, the ratio of the height to the diameter of the bump can be made larger than before. For example, when the diameter of the bump is the same as the conventional one, the height of the bump can be made higher than before, and when the height of the bump is the same as the conventional one, the diameter of the bump can be made smaller than before.

Therefore, even if the flatness of the film carrier or the substrate is varied, or if the inclination or warpage occurs, the height of the bumps is high. Pressure can be applied with a load necessary for bonding, partial bonding failure can be prevented, and stable bonding can be obtained for all bumps.

Further, even when the bumps are made smaller by reducing the pad pitch, the height can be made sufficiently higher than the diameter of the bumps. It is possible to provide a sufficient margin. As a result, even if the density and the number of pins are further increased, mounting of electronic components with bumps does not become difficult, and an improvement in mounting yield can be expected.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A case in which a bump according to the present invention is formed on an electrode pad of a semiconductor device using a wire bonder for ball bonding will be described with reference to the drawings. First, as shown in FIG. 1, a wire 1 such as a gold wire is transferred to a capillary 2 of a wire bonding wire bonder, and the tip of the wire 1 is heated by a discharge with a discharge electrode 3 to be welded. 4 is formed.

Next, as shown in FIG.
Is lowered to push down the ball 4 so that the ball 4 comes into contact with the electrode pad 6 of the semiconductor element 5 which has been heated in advance. The load and the ultrasonic wave are applied while crushing the ball 4 as it is, and the ball 4 is bonded to the electrode pad 6. When the joining is completed, as shown in FIG. 3, the clamper 7 installed above the capillary 2
Then, the clamper 7 is moved up together with the capillary 2 by holding the wire 1 and the wire 1 is cut apart to form the first bump 8a.

Thereafter, the above operation is repeated again to form a second bump on the first bump. That is, as shown in FIG. 4, the ball 4 formed at the tip of the wire 1 is brought into contact with the first bump 8a, and the ball 4 is crushed and joined as described above. Next, the clamper 7 is moved up together with the capillary 2 to cut the wire 1 apart, and as shown in FIG. 5, the second bump 8b is formed on the first bump 8a.

The bump 8 of the present invention thus formed as shown in FIG. 5 is composed of the first bump 8a and the second bump 8b, so that the conventional bump (the first bump 8a shown in FIG. The same applies to (b), so that the bump height h can be increased. Also, even when the diameter of the bump 8 is reduced,
The bump height h is relatively higher than the conventional single bump.

The first bump 8a and the second bump 8b
As shown in FIG. 6, the semiconductor element 5 provided with the bumps 8 is formed by connecting the bumps 8 on the electrode pads 6 to, for example, the external electrodes 10 on the substrate 9 by pressure bonding. Accordingly, the semiconductor device can be configured by mounting as usual.

[0023]

According to the present invention, since the bump height can be made higher than before, the flatness of the film carrier or the substrate to which the semiconductor element is to be bonded varies, and the bump or the tilt is generated. However, the whole can be pressurized with a load necessary for joining, and good joining without joining defects can be achieved.

Further, since the pitch of the pads is further narrowed by increasing the number of bins, the height can be relatively increased with respect to the diameter of the bumps even when the bumps are reduced. A margin can be given to the space between the bumps, and mounting by bumps can be performed relatively easily.

[0025] Therefore, no partial failure occurs in the connection by the bumps, and the mounting can be performed easily and reliably at a high yield, which is sufficient for the demand for miniaturization, high density, and multi-pin of the semiconductor device. It is possible to respond.

[Brief description of the drawings]

FIG. 1 is a schematic partially cutaway side view showing a ball forming step in the method of the present invention.

FIG. 2 is a schematic partially cutaway side view showing a ball joining step in the method of the present invention.

FIG. 3 is a schematic partially cutaway side view showing a step of forming a first bump in the method of the present invention.

FIG. 4 is a schematic partially cutaway side view showing a step of ball bonding for a second bump in the method of the present invention.

FIG. 5 is a schematic side view showing a semiconductor device with bumps of the present invention.

FIG. 6 is a schematic side view showing a state where the semiconductor device with bumps of the present invention is connected to a substrate.

FIG. 7 is a schematic side view showing a state where a conventional semiconductor device with bumps is connected to a substrate.

[Explanation of symbols]

 Reference Signs List 1 wire 2 capillary 3 discharge electrode 4 ball 5 semiconductor element 6 electrode pad 7 clamper 8 pad 8a first pad 8b second pad 9 substrate 10 external electrode

Claims (3)

[Claims] In a method of forming a bump used for electrical connection of an electronic component, a first bump is formed on a conductor portion of the electronic component, and then a second bump is stacked on the first bump. A method of forming a bump, characterized in that the bump is formed. 2. A ball bonding wire bonder is used to heat and melt the tip of the wire transferred to the capillary to form a ball, and the capillary is lowered to bring the ball into contact with the conductor of the electronic component. And applying a load and ultrasonic waves to form a first bump on the conductor, and then forming a second bump on the first bump. 3. The method for forming a bump according to 1. 3. An electronic component with bumps, comprising: a first bump provided on a conductor of the electronic component; and a second bump formed on the first bump.