JPH11274238A - Structure and method for mounting electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide structure and a method for mounting electronic component, with which a substrate and an electronic component are easily aligned and reliability is improved. SOLUTION: Conductor patterns 2, 3, 4 and 5 are formed on the upper surface of a plastic film 1 and pads 6, 7, 8 and 9 are formed at the terminal parts. Bumps 12, 13, 14 and 15 are formed on the lower surface of a flip chip 10 and connected with pads 6-9 of the conductor patterns 2-5. A sheet-shaped adhesive agent 16 is arranged between the area, where the conductor patterns 2-5 are absent, on the upper surface of the plastic film 1 and the area, where the bumps 12-15 are absent, on the lower surface of the flip chip 10 and the plastic film 1 and the flip chip 10 are adhered by this adhesive agent 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the mounting of electronic components, and more particularly, to the mounting of electronic components such as IC chips mounted on electronic products such as IC cards, remote cards, card calculators and card radios. Things.

[0002]

2. Description of the Related Art In recent years, IC cards and the like have become widespread for security management of companies, logistics management of air baggage, etc., commuter passes of JR and private railways, and so on. As one of the methods for mounting an IC chip on this IC card, a flip chip mounting method suitable for lightness, shortness, small size, and high density is applied.

Here, the flip-chip mounting method is as follows. As shown in FIGS. 6 and 7, a plastic film (eg, PET film) 2 is used as a substrate.
The conductor pattern 21 serving as a wiring for the antenna and the electronic circuit portion is formed on the upper surface of the substrate. As the conductive pattern 21, a conductive paste such as an Ag paste or an (Ag + C) paste is used. On the other hand, silicon chip 2
A bump (projection electrode) 23 is provided on the lower surface of 2. At the time of mounting, the anisotropic conductive film 24 is arranged on the upper surface of the plastic film 20. The anisotropic conductive film 24 is obtained by dispersing conductive particles 24b on an insulating adhesive resin material 24a. Then, the silicon chip 22 is pressed on the upper surface of the plastic film 20 via the anisotropic conductive film 24 as shown in FIGS.
The silicon chip 22 is mounted on the upper surface of the plastic film 20 by curing the anisotropic conductive film 24 by heat while applying the load F.

However, the anisotropic conductive film 24 needs to be attached also on the pad 21a of the conductive pattern 21, as shown in FIGS. Therefore, when aligning the silicon chip 22 with the pad 21a, the pad 21
Since the anisotropic conductive film 24 is present on a, the pad portion is difficult to see, and it may be difficult to perform positioning.

Further, since the area where the anisotropic conductive film 24 is attached covers the entire silicon chip 22,
As shown in FIGS. 8 and 9, there is a concern that the resin component 24 a of the anisotropic conductive film 24 is interposed between the conductor pattern 21 and the bump 23, and the reliability is deteriorated.

[0008] Further, as shown in FIGS. 8 and 9, the area to which the anisotropic conductive film 24 is attached covers the entire chip 22. The heat causes the anisotropic conductive film 24 to protrude from the silicon chip 22 and to cover the conductive pattern 21. When a durability test is performed in this state, stress is generated at the interface between the anisotropic conductive film 24 covering the conductor pattern 21 and another member (the location indicated by X in FIG. 9), and the conductor pattern 21 is disconnected. A problem occurred.

On the other hand, Japanese Patent Application Laid-Open No. 58-197793,
In Japanese Unexamined Utility Model Publication No. Hei 5-33572, an adhesive is applied to a region other than a joining portion for joining an electronic component and a substrate by a dispenser or printing, thereby providing an electronic component mounting structure with an increased joining strength.

However, in this method, since the adhesive is in a liquid state, the adhesive may be applied to cover the conductor pattern (wiring) when the chip and the substrate are joined.
The above problems cannot be solved. In addition, when a liquid adhesive is used, the substrate must have a dam structure in order to prevent the adhesive from flowing out, and problems such as adhesion to other parts must be solved. In addition, there is a problem in the process of applying the adhesive, for example, a problem of cleaning and replacement of the dispenser, and a problem of cleaning and replacement of the screen mask in the case of printing.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide a mounting structure of an electronic component and a method of mounting the electronic component, which can easily align the substrate and the electronic component and have high reliability. .

[0010]

According to a first aspect of the present invention, there is provided a mounting structure for an electronic component, which is disposed between a region having no conductive pattern on the upper surface of the substrate and a region having no electrode on the lower surface of the electronic component. It is characterized in that a sheet-like adhesive for bonding the electronic component is provided.

That is, as in the mounting method according to the second aspect, a sheet-like adhesive before curing is applied between a region on the upper surface of the substrate where no conductor pattern is present and a region on the lower surface of the electronic component where there is no electrode. In the arranged state, the conductive pattern formed on the upper surface of the substrate and the electrode formed on the lower surface of the electronic component are brought into contact with each other, and then the adhesive in the form of a sheet is cured to bond the substrate and the electronic component.

[0012] Therefore, since it is only necessary to apply a sheet-like adhesive to a desired place of the substrate or the electronic component and press-fit it, it is very easy to make. In other words, compared to a liquid adhesive, it is possible to make the process very easy because there is no need for setup and post-processing (replacement and cleaning of processing jigs).

Further, since the adhesive does not exist between the electrode and the conductor pattern, it is possible to mount an electronic component with high reliability in electrical connection. Further, since the adhesive does not exist in the entire area of the electronic component, it is possible to avoid the occurrence of stress at the interface between the resin part of the adhesive and another member, and the disconnection of the conductor pattern.

Further, since the adhesive does not cover the conductive pattern, the positioning of the board and the electronic component during assembly becomes easy. Here, as a third aspect of the present invention, as a method for mounting the electronic component, the conductive pattern and the electrode may be brought into contact with each other from a state where a sheet-like adhesive before curing is attached to the upper surface of the substrate.

Alternatively, as a fourth aspect of the present invention, as a method for mounting an electronic component, the conductive pattern and the electrode may be brought into contact with each other after the uncured sheet-like adhesive is attached to the lower surface of the electronic component. Good.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. The present embodiment is applied to flip chip mounting on an IC card as a target product.

FIG. 1 is a plan view showing the entire structure, and FIG.
1 shows a sectional view taken along the line AA of FIG. A plastic film (for example, PET film) 1 is used as a substrate. On the upper surface of the plastic film 1, conductor patterns 2, 3, 4, and 5 serving as wiring for an antenna and an electronic circuit portion are formed, and circular pads 6, 7 are provided at ends of the conductor patterns 2, 3, 4, and 5, respectively. , 8, 9 are formed. The conductor patterns 2, 3, 4, and 5 are arranged by printing a paste on the upper surface of the plastic film 1.
Here, Ag paste, Cu paste, C
Paste or the like is used. Conductor patterns 2, 3, 4, 5
Has a thickness of 10 to 20 μm.

In addition to the paste, a Cu thin film or Au
The conductive patterns 2, 3, 4, and 5 may be formed by forming a thin film at a desired position. On the other hand, in a flip chip 10 as an electronic component to be mounted, a bump (projection electrode) 1 is provided on the lower surface of a silicon chip (IC chip) 11.
2, 13, 14, and 15 are formed. Bump 12,
13, 14, 15 are made of, for example, Cu, Ag, or the like;
Diameter is 50-300 μm and height is 30-100 μm
Column-shaped or mushroom-shaped bumps. This bump 1
2, 13, 14, 15 are conductor patterns 2, 3, 4, 5
Slightly penetrate into the pads 6,7,8,9.
The bite amount is about 5 to 10 μm.

Between the upper surface of the plastic film 1 and the lower surface of the flip chip 10, a rectangular sheet-like (film-like) adhesive 16 is arranged. Specifically, the rectangular sheet-like adhesive 16 is made of a thermosetting adhesive, and the area of the upper surface of the plastic film 1 where the conductor patterns 2, 3, 4, 5 are not provided and the flip chip 1
It is arranged between the lower surface of the "0" and the region where the bumps 12, 13, 14, 15 are not provided. This sheet-like adhesive 1
6, plastic film 1 and flip chip 10
And are glued.

Therefore, the bumps 12 to 15 and the pads 6 to 9 are electrically connected without any intervening between the bumps 12, 13, 14, 15 and the conductor patterns 2, 3, 4, 5. . Hereinafter, the sheet-like adhesive 16 is referred to as an “adhesive sheet”.

Next, a method of mounting the flip chip 10 will be described. As shown in FIGS. 3 and 4, a plastic film (PE) having conductor patterns 2, 3, 4, 5 formed on the upper surface thereof
T film) 1 is prepared. In addition, the silicon chip 11
A flip chip 10 having bumps 12, 13, 14, 15 provided on the lower surface of the chip is prepared. Then, an uncured adhesive sheet 16 ′ is attached to a region of the upper surface of the plastic film 1 where the conductor patterns 2, 3, 4, and 5 do not exist. This adhesive sheet 16 'is solidified and does not flow freely. Therefore, the rectangular adhesive sheet 16 ′ can be attached to a desired position on the upper surface of the plastic film 1 using tweezers or the like, and the attaching operation of the adhesive sheet 16 ′ is easy because the adhesive sheet itself has adhesiveness. .

Further, as shown in FIGS. 1 and 2, the flip chip 10 is positioned on the plastic film 1 and the pads 6, 7, and 4 of the conductor patterns 2, 3, 4, and 5 are aligned.
8, 9 and bumps 12, 13, 1 of flip chip 10
4, 15 are brought into contact.

When positioning the plastic film 1 and the flip chip 10, the adhesive sheet 1
6 'is the pad 6,7, of the conductor pattern 2,3,4,5
Since they are not located on the positions 8, 9, the pads 6, 7, 8, 9 are easy to see. Therefore, flip chip 10 and pad 6,
7, 8, and 9 can be easily positioned.

Subsequently, the flip chip 10 is
Is heated while pressing downward. More specifically, for example, pressure and heat are applied at a temperature of 150 to 200 ° C., a time of 15 to 30 seconds, and a pressure of 50 to 150 MPa.

In this way, the adhesive sheet 16 ′ is cured, and the plastic film 1 and the flip chip 10 are bonded. In the pressure bonding step (curing step), the adhesive 16 is applied to the flip chip 1 by the applied load and heat.
Without protruding from 0, conductor patterns 2, 3, 4,
5 does not cover the adhesive sheet 16. For that purpose, adhesive 1
There is no problem that stress is generated at the interface between 6 and another member and the wiring of the electronic circuit section is disconnected.

In the IC card thus mounted on the flip chip, the adhesive 16 is applied to the bumps 12 and 1.
3, 3, and 15 are not present between the conductor patterns 2, 3, 4, and 5. Therefore, there is no fear that the reliability will be deteriorated.

Also, Japanese Patent Application Laid-Open No. 58-197793,
As disclosed in Japanese Utility Model Application Laid-Open No. 5-33572, when a liquid adhesive is used, a conductive pattern (wiring) may be covered when joining the chip and the substrate after the adhesive is applied, or the adhesive may be used. There are problems such as the need to provide a dam on the substrate to prevent run-off, taking measures to avoid adhesion to other parts, and the necessity of cleaning and replacing the dispenser and screen mask when applying adhesive. In the example, these problems can be solved by mounting using the solidified adhesive sheet 16 '.

As described above, this embodiment has the following features. (A) As a flip-chip mounting structure, a region on the upper surface of the plastic film 1 where the conductor patterns 2, 3, 4, and 5 do not exist, and a bump 1 on the lower surface of the flip chip 10
An adhesive sheet (sheet-like adhesive) 16 was arranged between the areas without 2, 13, 14, and 15 to bond the plastic film 1 and the flip chip 10 together. That is, the plastic film 1 is used as a flip chip mounting method.
And the bumps 12 and 1 on the bottom surface of the flip chip
The conductor patterns 2, 3, 4, formed on the upper surface of the plastic film 1 in a state in which the uncured adhesive sheet (sheet-like adhesive) 16 'is arranged between the regions where there is no 3, 14, 15 5 and the bumps 12, 13, 14, and 15 formed on the lower surface of the flip chip 10 were brought into contact with each other, and then the adhesive sheet 16 'was cured to bond the plastic film 1 and the flip chip 10.

Therefore, since the adhesive sheet (16 ') is simply stuck to a desired place of the plastic film 1 and pressed, it is very easy to make. In other words, compared to liquid adhesive, setup and post-processing (replacement of processing jig,
(E.g., washing), and the process can be made very easy.

Further, the adhesive (16) is applied to the bumps 12,1.
Since there is no space between the conductor patterns 3, 14, 15 and the conductor patterns 2, 3, 4, 5, flip-chip mounting with high reliability in electrical connection is possible. That is, it is possible to prevent an increase in connection resistance caused by a cooling / heating cycle or the like.

Further, since the adhesive (16) does not exist in the whole area of the chip, stress is generated at the interface between the resin portion of the adhesive (16) and another member, and the conductor patterns (2, 3, 4, 5) are disconnected. Is avoided.

The adhesive (16) is used for the conductor pattern 2,
Since the plastic film 1 and the chip 10 are not covered with 3, 4, and 5, the positioning of the plastic film 1 and the chip 10 at the time of assembly becomes easy. (B) As a flip-chip mounting method, the conductor patterns 2, 3, 4, 5 and the bumps 12,
13, 14, and 15 are brought into contact with each other, which is practically preferable.

In addition to the embodiment described above, the present invention may be implemented as follows. The adhesive sheet 16
As shown in FIG. 5, in addition to being previously attached to the plastic film 1 as shown in FIG.
May be pasted in advance. In other words, the conductive patterns 2, 3, 4, 5 and the bumps 12, 13, 14, 15 may be brought into contact with the uncured sheet adhesive 16 'adhered to the lower surface of the flip chip 10. Good.

The case where a thermosetting adhesive is used as the adhesive sheet 16 has been described.
For example, an adhesive sheet made of a photo-curable adhesive may be used as 6, and in this case, it is cured by irradiating light.

Although the case where the present invention is applied to an IC card has been described above, in addition to the IC card, electronic products such as a remote card, a card calculator, a card radio, etc.
The present invention may be applied to a case where an electronic component such as a chip is mounted.

[Brief description of the drawings]

FIG. 1 is a plan view showing an overall configuration according to an embodiment.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a plan view for explaining a mounting step.

FIG. 4 is a sectional view taken along line BB of FIG. 3;

FIG. 5 is a view showing an electronic device in another example.

FIG. 6 is a plan view for explaining a conventional flip chip mounting method.

FIG. 7 is a sectional view taken along the line CC of FIG. 6;

FIG. 8 is a plan view for explaining a conventional flip chip mounting method.

FIG. 9 is a sectional view taken along line DD of FIG. 8;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... plastic film, 2 ... conductor pattern, 3 ... conductor pattern, 4 ... conductor pattern, 5 ... conductor pattern, 6
... pad, 7 ... pad, 8 ... pad, 9 ... pad, 10
... Flip chip, 12 ... Bump, 13 ... Bump, 14
... Bump, 15 ... Bump, 16 ... Adhesive sheet

Claims (4)

[Claims] A substrate having a conductor pattern formed on an upper surface thereof; an electronic component having an electrode connected to the conductor pattern formed on a lower surface; a region having no conductor pattern on the upper surface of the substrate and a lower surface of the electronic component. And a sheet-like adhesive for adhering the substrate and the electronic component, the electronic component mounting structure comprising: 2. The method according to claim 1, further comprising forming an uncured sheet-like adhesive between the region without the conductor pattern on the upper surface of the substrate and the region without the electrodes on the lower surface of the electronic component. An electronic component, comprising: a step of bringing a conductor pattern into contact with an electrode formed on a lower surface of the electronic component; and a step of curing the sheet-like adhesive to adhere the substrate to the electronic component. How to implement. 3. The electronic component mounting method according to claim 2, wherein the conductive pattern and the electrode are brought into contact with each other from a state in which a sheet-like adhesive before curing is attached to the upper surface of the substrate. 4. The method for mounting an electronic component according to claim 2, wherein the conductive pattern and the electrode are brought into contact with each other after a sheet-like adhesive before curing is attached to the lower surface of the electronic component.