JP2001284380A - Semiconductor device mounting method - Google Patents

Abstract

(57) [Summary] [PROBLEMS] Conventionally, at the time of face-down bonding, molten solder flows out of a connection pad during face-down bonding,
There has been a problem that the height of the protruding electrode is reduced, the gap between the semiconductor chip and the circuit board is narrowed, and the thermosetting resin cannot be injected into this gap. According to the present invention, a semiconductor chip having a large number of protruding electrodes formed on a surface thereof is prepared. When the bumps 2 of the semiconductor chip 1 are fixed to the circuit board 3 by heating and melting, the metal bumps 7
Thus, a constant gap is formed between the circuit board 3 and the semiconductor chip 1 to realize a semiconductor device mounting method which solves the conventional problem.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method of mounting a semiconductor device, and more particularly to a method of mounting a chip having a large number of projecting electrodes.

[0002]

2. Description of the Related Art FIG. 4 shows a method of mounting a flip-chip type semiconductor device.

[0003] On one main surface of a semiconductor chip 1, a number of protruding electrodes 2 are formed at regular intervals around the periphery. That is, a base electrode 6 made of a nickel layer and a gold layer connected to an internal circuit is provided in a portion where the bump electrode 2 is formed, and a bump electrode made of 100 μm high solder is provided on the base electrode 6 by a solder reflow apparatus. 2 is provided. Subsequently, the protruding electrode 2 is connected to a connection pad 4 formed of a copper foil or the like of the circuit board 3 by face-down bonding with the protruding electrode 2 facing downward. In this step, the bump electrode 2 is heated and melted in a reducing atmosphere, and the semiconductor chip 1 is mounted on the circuit board 3 by face-down bonding. At this time, the solder of the protruding electrode 2 flows out of the conductive path from the connection pad 4 by about 200 μm,
The height of the protruding electrode 2 decreases from the original 100 μm to 20 μm or less. Therefore, the gap between the semiconductor chip 1 and the circuit board 3 becomes extremely narrow.

Since the semiconductor chip 1 and the circuit board 3 have different coefficients of thermal expansion, the stress is applied to the solder of the protruding electrodes 2 to prevent the protruding electrodes 2 from peeling off from the connection pads 4 and to prevent the semiconductor chip 1 from being exposed to the outside air. A thermosetting resin 5 is provided in the gap between the semiconductor chip 1 and the circuit board 3 to protect the
Has been injected.

Recently, the pitch of the protruding electrodes 2 has been steadily reduced due to the increase in the number of pins of the device, and the height of the protruding electrodes 2 has been reduced to 100 μm.
m to 50 μm.

[0006]

The conventional method for mounting a semiconductor device has various problems.

The protruding electrode 2 is formed to a height of about 100 μm. During the face-down bonding, the molten solder flows out from the connection pad 4 to the conductive path connected thereto, and the height of the protruding electrode 2 becomes about 20 μm. Down to Therefore, the gap between the semiconductor chip 1 and the circuit board 3 is about 20 μm.
m, and the thermosetting resin 5 cannot be injected into this gap by utilizing the capillary phenomenon. In particular, when the height of the projecting electrode 2 is 5
When the thickness is 0 μm, this tendency is further increased. In a severe case, the height of the protruding electrode 2 is lost, and the injection of the thermosetting resin 5 becomes impossible.

As a result, the semiconductor chip 1 cannot be protected by the thermosetting resin 5, and the protruding electrodes 2 are peeled off from the connection pads 4 of the circuit board 3 by thermal stress, and the semiconductor chip 1 is sufficiently protected from the outside air. become unable.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and a chip having a large number of projecting electrodes formed on a surface thereof is not melted by heating and melting the projecting electrode on the surface of the chip. A plurality of metal bumps are provided, and a fixed gap is formed between the circuit board and the chip by the metal bumps when the bump electrodes of the chip are fixed to the circuit board by heating and melting. Having.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for mounting a semiconductor device according to the present invention will be described with reference to FIGS.

FIG. 1 is a plan view of a semiconductor chip used in the present invention. On one main surface of the semiconductor chip 1, a number of protruding electrodes 2 are formed at regular intervals around the periphery. That is, a base electrode 6 made of a nickel layer and a gold layer connected to an internal circuit is provided in a portion where the bump electrode 2 is formed, and a bump electrode made of 100 μm high solder is provided on the base electrode 6 by a solder reflow apparatus. 2 is provided.

A feature of the present invention is to provide a plurality of metal bumps 7. Metal bump 7 should be between 25 μm and 30
A ball formed by heating and melting a gold wire having a diameter of μm using a hydrogen torch with a ball bonding apparatus is used as a semiconductor chip 1.
Are formed by thermocompression bonding to the base electrodes 6 provided at the four corners. The metal bump 7 has a diameter of, for example, 60 μm to 80 μm.
The height is about 50 μm. Metal bump 7
Are provided at least at two corners on the diagonal line of the semiconductor chip 1 so that the gap between the semiconductor chip 1 and the circuit board 3 is maintained at 50 μm. Ideally, if the metal bumps 7 are provided at the four corners of the semiconductor chip 1, the semiconductor chip 1 can be stably supported.

The metal bump 7 can be made of a metal piece having a thickness of about 50 μm. A metal piece of iron or copper is fixed to a position between two and four corners of the semiconductor chip 1 with an adhesive or the like.

In the semiconductor chip 1 described above, the protruding electrode 2 is brought into contact with a connection pad 4 connected to a conductive path formed of a copper foil or the like provided on the circuit board 3 with the protruding electrode 2 facing downward. In a reducing atmosphere, an N ² atmosphere, or an air atmosphere, the projecting electrode 2 is heated and melted using a flux for solder bonding, and the semiconductor chip 1 is mounted on the circuit board 3 by face-down bonding. At this time, the solder of the protruding electrode 2 flows out of the connection pad 4 through the conductive path by about 200 μm, and the height of the protruding electrode 2 is reduced from the original 100 μm, but the metal bump 7 does not melt and the semiconductor chip 1 It is supported by forming a gap of about 50 μm with the circuit board 3. Accordingly, the protruding electrode 2 has a column shape, and good connection with the connection pad 4 can be obtained.

A space between the semiconductor chip 1 and the circuit board 3 is filled with a thermosetting resin 5 serving as an underfill resin made of an epoxy resin or the like by utilizing a capillary phenomenon. This thermosetting resin 5 is dropped into a liquid on the side of the semiconductor chip 1 and injected into the gap. The thermosetting resin 5 prevents a stress generated due to a difference in thermal expansion coefficient between the semiconductor chip 1 and the circuit board 3 from being applied to the solder of the projecting electrode 2, thereby preventing the projecting electrode 2 from peeling off from the connection pad 4. Also,
It also has a function of protecting the semiconductor chip 1 from the outside air.

[0016]

According to the present invention, first, the semiconductor chip 1
A plurality of metal bumps 7 that are not melted even when the protruding electrode 2 is heated and melted are provided on the surface of the semiconductor chip 1. By forming a fixed gap between the circuit board 3 and the semiconductor chip 1, the thermosetting resin 5 can be injected in a short time by utilizing the capillary phenomenon, and can be uniformly injected because of the fixed gap. Has advantages.

Second, since the metal bumps 7 are formed from bonding wires having a constant thickness formed during ball bonding, they can be formed at a uniform height, and the existing bonding apparatus can be used, and a new method can be used. No capital investment is required.

[Brief description of the drawings]

FIG. 1 is a plan view illustrating a method for mounting a semiconductor device of the present invention.

FIG. 2 is a cross-sectional view illustrating a method for mounting the semiconductor device of the present invention, and is a cross-sectional view taken along line AA of FIG.

FIG. 3 is a sectional view illustrating a method for mounting a semiconductor device of the present invention.

FIG. 4 is a cross-sectional view illustrating a conventional method for mounting a semiconductor device.

Claims (4)

[Claims] 1. A chip having a large number of protruding electrodes formed on a surface thereof is provided, and a plurality of metal bumps which are not melted by heating and melting the protruding electrodes are provided on a surface of the chip, and the chip of the chip is mounted on a circuit board. A method of mounting a semiconductor device, wherein a fixed gap is formed between the circuit board and the chip with the metal bump when the protruding electrode is fixed by heating and melting. 2. The method according to claim 1, wherein the protruding electrodes are formed of solder. 3. The method according to claim 1, wherein the metal bump is formed by fixing a ball formed by melting a bonding wire of a gold wire. 4. The method according to claim 1, wherein the metal bumps are formed on the chip surface.
2. The method according to claim 1, wherein the semiconductor device is provided at a plurality of locations.