JP3251810B2 - Mounting method of integrated circuit device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for mounting an integrated circuit device, and more particularly, to a method for mounting an integrated circuit device on a wiring board with an improved mounting density.

[0002]

2. Description of the Related Art With the development of integrated circuit technology, the degree of integration of one chip tends to increase, and the number of input / output terminals tends to increase. In such a multi-terminal integrated circuit, QFP
A resin package called “QuadFlat Package” having leads on four sides and a package called PGA (Pin Grid Array) having an array of terminals on the bottom surface of the package are used.

[0003] In these packages, since the lead interval is increased to a level at which soldering, which is a means for mounting on a normal wiring board, is possible, the package is inevitably large, and the area occupied on the wiring board is large. . Therefore, TAB (Tape Automated
Bonding) method may be adopted.

In the TAB method, an integrated circuit chip is bonded to inner leads of a well-known TAB tape,
After the electrical inspection, the tape is cut from the tape at the outer lead portion, and if necessary, is lead-formed and mounted on a wiring board.

FIG. 8 is a sectional view showing the mounting of a TAB type substrate. The integrated circuit chip 100 is connected to inner leads 104 of a TAB tape via bump electrodes 102. The plurality of inner leads 104 are insulated and held by the support ring 106 in an aligned state, and the outer leads 108 are connected to the conductor wiring 112 of the wiring board 110.

In the TAB method, although the area occupied is smaller than that of the QFP, the mounting area is larger than the chip area because the leads are extended around the chip 100. As the high-density mounting of the wiring board progresses, the area occupied by the leads cannot be ignored.

[0007]

As described above, as the mounting density of the wiring board increases, the mounting density of the TAB type lead portion cannot be ignored. The present invention has been made in view of the above circumstances, and has as its object to provide a mounting method of an integrated circuit that can be mounted at a chip size level using a tape.

[0008]

In order to solve the above-mentioned problems, a method of mounting an integrated circuit device according to the present invention comprises the steps of forming a plurality of bump electrodes in an integrated circuit device mounting area of a wiring board; A plurality of wiring conductors formed on the main surface of the conductive film from the center toward the end, and formed on each of the wiring conductors, the first electrode formed on the center, and the end formed on the end. Connecting the first electrode of the wiring film having the second electrode to the corresponding bump electrode of the wiring substrate, and bonding the lower surface of the integrated circuit device having the plurality of third electrodes on the upper surface Placing the wiring film at a substantially central portion on the wiring film via an agent, and bending the end portion of the wiring film along the periphery of the integrated circuit device;
Connecting the second electrode of the wiring film to a corresponding third electrode of the integrated circuit device.

At this time, when the plurality of bump electrodes are formed on the wiring substrate, an insulating film having a thickness protruding from the bump electrode head is formed on the substrate together with the bump electrode region. It is desirable.

In another mounting method of the present invention, a plurality of wiring conductors are formed on a main surface of a flexible film from a central portion toward an end, and the wiring conductors are formed on each of the wiring conductors. Forming a bump electrode on the first electrode of the wiring film having a first electrode formed on the substrate and a second electrode formed on the end portion; Connecting the plurality of third electrodes formed on the substrate in correspondence with each other, and connecting the lower surface of the integrated circuit device having the plurality of fourth electrodes on the upper surface to the substantially central portion of the wiring film via an adhesive; And bending the wiring film along the periphery of the integrated circuit device,
Connecting the corresponding second electrode of the wiring film to a fourth electrode of the integrated circuit device.

At this time, when connecting the bump electrode of the wiring film to each of the plurality of third electrodes formed on the wiring board, the bump electrode has a thickness such that the head of the bump electrode is exposed. It is preferable that the insulating film is interposed between the wiring film and the wiring board, avoiding the bump electrode region.

[0012]

As described above, in the present invention, a wiring film made of a flexible film is connected to a wiring board in advance. At this time, the connection region is set to a range that fits on the back surface of the integrated circuit chip to be mounted later. Thereafter, the integrated circuit chip is mounted on the wiring film, and the film is bent to wrap the integrated circuit chip and connect to the electrodes on the upper surface of the chip. As a result, the connection area of the integrated circuit chip can be kept within the chip size, and the mounting density of the wiring board can be improved.

At this time, if an insulating film having such a thickness as to expose the head of the bump electrode is interposed between the wiring board and the wiring film, the integrated circuit chip is firmly fixed to the wiring board. Good bonding between the chip and the wiring conductor of the wiring film can be performed.

[0014]

Embodiments will be described below with reference to the drawings. (Embodiment 1) FIG. 1 is a schematic cross-sectional view of a mounting body mounted by a mounting method of an integrated circuit device according to a first embodiment of the present invention, and FIGS. FIG. 2 is a cross-sectional view of a mounting body schematically shown. FIG. 4 is a plan view (bottom view) schematically showing a wiring film used for this mounting. Although the wiring is described only in the left quarter region, it goes without saying that the wiring is similarly formed in the entire region.

That is, a gold bump 18 formed in a connection hole of an insulating film 16 made of polyimide or the like adhered on the wiring conductor 14 of the wiring board 12 and a gold-plated copper adhered to one surface of an insulating film 20 made of polyimide or the like. The wiring 22 is thermocompression bonded, the integrated circuit chip 10 is wrapped with the insulating film 20 via the insulating adhesive 24, and the bump electrode 26 of the integrated circuit chip 10 and the gold plated copper wiring 22 are thermocompression bonded. ing. The wiring conductors 14 are separated from each other and individually connected to the gold bumps 14, but are illustrated as one wiring in order to avoid complication of the drawing.

A mounting method according to this embodiment will be described with reference to FIGS. First, a copper wiring conductor 14 is adhered to a surface layer of a wiring board substrate 12 made of glass epoxy or polyimide. This substrate may be a multilayer substrate including a wiring conductor in an inner layer. A connection hole 15 is formed on the wiring conductor 14.
Is adhered to the perforated polyimide insulating film 16 (FIG. 2A). The connection hole 15 is formed in a mounting area of an integrated circuit chip to be mounted later. Next, gold plating is selectively deposited inside the connection hole 15 to form the gold bump 1.
8 is formed. The gold bumps 18 are preferably formed so as to protrude from the surface of the polyimide insulating film 16 (FIG. 2B).

Subsequently, a wiring film having a copper wiring 22 adhered to the polyimide insulating film 20 is prepared. FIG. 4 shows a plan view of this wiring film, which can be manufactured by the same process as a normal TAB tape. The surface of the copper wiring 22 is plated with gold. This gold plating may be replaced with tin plating. An opening 30 corresponding to the gold bump 18 is provided in the polyimide film 20 at the center of the wiring film, so that the copper wiring 22 is exposed. Since the polyimide film is translucent and the lower substrate can be directly viewed through the opening 30, alignment is easy.

The individual copper wirings are generally terminated at the openings 30, but may be formed continuously with other edges as shown in the upper left corner of FIG. However, in the cross-sectional view of FIG. 3, the copper wiring 22 is illustrated as a single line in order to avoid complication of the drawing. The opening 30 and the gold bump 18 are aligned, and a bonding tool 28 is pressed to perform thermocompression bonding (FIG. 3A).

Subsequently, the integrated circuit chip 10 is mounted on the center of the wiring film via an adhesive 24. Adhesive 2
It is desirable to use a heat-resistant adhesive such as an epoxy-based or polyimide-based adhesive 4 (FIG. 3B).

Next, while holding the polyimide film portion 20a at the end of the wiring film, it is molded so as to enclose the chip 10 side by side, and the electrode 26 of the chip 10 and the copper wiring 22 of the wiring film are bonded by thermocompression bonding. I do. At this time, since the integrated circuit chip 10 is firmly fixed to the wiring board 12 via the polyimide film 16, bonding can be easily performed.

After the completion of the bonding, the polyimide film portion 2 is so formed as not to hinder the bonding of the other side.
Oa may be bent vertically, and in this case, lead cutting may be performed near the bent portion 32 at this stage. The lead cut may be performed by any means that does not adversely affect the bonding portion and the chip. For example, the lead cut is performed by laser cutting (FIG. 3C).

By performing this lead bonding on each side, a package as shown in FIG. 1 is obtained. According to this mounting method, since the connection portion with the wiring board 12 is accommodated on the back surface of the chip 10, the mounting density of the wiring board can be increased. As shown in FIG. 4, not only the peripheral portion of the chip but also the central portion can be used as the connection portion between the wiring film and the substrate, so that the wiring area can be expanded. The concept of using the chip central portion also for the bonding area can be applied to bonding on the upper surface of the chip.

In this embodiment, the gold bump 18 is
Although provided on the wiring film side, it may be provided on the wiring film side. Embodiment 2 Various modifications are conceivable as a mounting method of the mounting body shown in FIG. FIG. 5 shows FIG. 2 of the first embodiment.
FIG. 3B is a modification of the step of FIG. In this embodiment, solder bumps 38 are formed at the connection portions of the wiring film and the wiring board 10. The solder bumps can be formed, for example, by printing solder cream.

A solder resist 34 is provided on the wiring conductor 14 of the wiring board 12, and an opening 36 for connection is opened. The solder bump 3 corresponding to the opening 36
Align 8 and hot tool from top (not shown)
Can be joined by thermocompression bonding. The alignment can be performed as appropriate by providing a through hole in the polyimide film 20 and providing an alignment mark on the wiring board side.

The subsequent steps are the same as in Example 1, but
It is desirable that the bump electrodes on the integrated circuit chip side have a temperature difference using solder (alloy) having a lower melting point than the solder bumps 38. For example, when an Sn-based alloy is used for the solder bump 38, an In-based alloy is used for the chip electrode. Also in this case, since the integrated circuit chip 10 is firmly fixed to the wiring board 12 via the polyimide film 34, bonding can be easily performed. (Embodiment 3) FIG. 6 shows the first embodiment shown in FIG.
(B) is still another modified example of the step of FIG.
In this embodiment, a conductive resin bump 38 is formed on the wiring conductor 22 of the wiring film. The bumps 38 can be formed, for example, by printing and drying a silver paste and, if necessary, by overprinting.

This is aligned with the wiring board 12 via the double-sided adhesive tape 40 having the opening 42 perforated, and then thermocompression-bonded. Wiring film and wiring board 12 with double-sided adhesive tape
And the conductive resin bumps 38 are pressed against and held by the wiring conductors 14 (copper or gold-plated copper) of the wiring board 12 to maintain conduction.

At this time, the base material of the double-sided adhesive tape 40 is preferably, for example, a polyimide resin, and the adhesive is preferably an uncured or semi-cured thermosetting resin. After that, the integrated circuit chip is connected as in the first embodiment.
For the bumps of the chip electrode 10, it is desirable to select an alloy having a melting point lower than the heat resistance temperature of the double-sided adhesive tape. (Embodiment 4) In the first to third embodiments, all wiring from the integrated circuit chip 10 is performed through the wiring film.
When the wiring pitch becomes narrow, the wiring becomes thin, and there is a case where the wiring resistance of the power supply and the ground becomes a problem.

The present embodiment is an improvement in such a case, in which the portion where the wiring resistance is desired to be reduced is made by another connection means, for example, wire bonding. As described above, even if the conventional technology is partially used, the mounting density can be relatively improved. Also in this case, the integrated circuit chip 10
Is firmly fixed to the wiring board 12 via the polyimide film 34, so that bonding can be easily performed.

Although several embodiments have been described above, the present invention is not limited to the above embodiments. After connecting the wiring film to the wiring board first, mount the integrated circuit chip,
As long as the chip is wrapped in a wiring film, these embodiments may be combined or some of them may be replaced with equivalent means.

[0030]

According to the mounting method of the present invention, the area occupied by the integrated circuit device on the wiring board can be substantially reduced to the chip area. In the case of the conventional TAB method, the connection is made at the peripheral portion of the integrated circuit chip. However, in the present invention, since the lower surface of the chip can be used, the degree of freedom of wiring increases, and proper wiring becomes possible.

The connection portion can be easily confirmed visually from the upper surface without hiding the connection portion between the wiring board and the wiring film and between the wiring film and the integrated circuit chip.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an integrated circuit device mounted body connected by a mounting method according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of a mounting body showing a mounting method according to the first embodiment of the present invention step by step.

FIG. 3 is a cross-sectional view of the mounting body showing the next stage of FIG. 2;

FIG. 4 is a plan (bottom) view of a wiring film used in the first embodiment of the present invention.

FIG. 5 is a cross-sectional view of a mounting body showing characteristic steps of a mounting method according to a second embodiment of the present invention.

FIG. 6 is a sectional view of a mounting body showing characteristic steps of a mounting method according to a third embodiment of the present invention.

FIG. 7 is a sectional view of a mounting body showing characteristic steps of a mounting method according to a fourth embodiment of the present invention.

FIG. 8 is a cross-sectional view of a mounting body showing a conventional TAB mounting method.

[Explanation of symbols]

10 integrated circuit chip, 12 substrate, 14 wiring conductor,
16 ... insulating film, 18 ... gold bump, 20 ... insulating film, 22 ... wiring conductor, 24 ... adhesive, 26 ... bump electrode

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 21/60 H01L 23/12

Claims (4)

(57) [Claims] A step of forming a plurality of bump electrodes in an integrated circuit device mounting area of a wiring board; a plurality of wiring conductors formed on a main surface of a flexible film from a center to an end; The first electrode of the wiring film, which is formed on each of the wiring conductors and has a first electrode formed at the center and a second electrode formed at the end, is connected to a corresponding one of the wiring substrates. Connecting the lower surface of the integrated circuit device having a plurality of third electrodes on the upper surface to a substantially central portion on the wiring film via an adhesive; Bending the end portion along the periphery of the integrated circuit device, and connecting the second electrode of the wiring film to a corresponding third electrode of the integrated circuit device. To implement integrated circuit devices . 2. The method according to claim 1, wherein the step of forming the plurality of bump electrodes on the wiring substrate includes the step of forming an insulating film having a thickness protruding from a head of the bump electrode on the integrated circuit device mounting area on the substrate. 2. The method according to claim 1, wherein the electrode is formed excluding the electrode region. 3. A plurality of wiring conductors formed on a main surface of a flexible film from a center to an end, and a first electrode formed on each of the wiring conductors and formed on the center. Forming a bump electrode on the first electrode of the wiring film having a second electrode formed on the end portion; and forming a plurality of bump electrodes on the wiring substrate on the first electrode of the wiring film. A step of mounting a lower surface of an integrated circuit device having a plurality of fourth electrodes on an upper surface at a substantially central portion of the wiring film via an adhesive; Bending a wiring film along the periphery of the integrated circuit device, and connecting the second electrode of the wiring film to a corresponding fourth electrode of the integrated circuit device. Mounting method of integrated circuit device 4. The method according to claim 1, wherein the bump electrode of the wiring film is
When connecting corresponding to each of the plurality of third electrodes formed on the wiring board, an insulating film having a thickness such that the head of the bump electrode is exposed corresponds to the integrated circuit device mounting area. 4. The method according to claim 3, wherein the wiring board is interposed between the insulating film and the wiring board in a region other than the bump electrode region.