JP2001237265A - Board for connecting electric apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problems incident to thermocompression of an ACF that 1) bubbles are generated, and 2) density of conductive particles is decreased by outflow of ACF. SOLUTION: In the board for connecting an electric apparatus where protrusion electrodes provided on the lower surface of an electric component is connected with wiring provided on a flexible insulating board through an anisotropic conductive film by thermocompression, a wall having a delivery part for guiding molten binder and bubbles generated at the time of thermocompression is provided at a position space apart from the wiring on the inside of the abutting position of the protrusion electrodes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate used for connecting an electric device such as a liquid crystal display device, a portable telephone, and an electronic computer, and more particularly to a substrate used for connecting an electric device formed of a flexible insulating substrate. .

[0002]

2. Description of the Related Art At present, a thin plate having flexibility, that is, a flexible and insulating property is used as a substrate, and electric components are mounted on the substrate to form a circuit or to perform electric wiring. It is used as a substrate to be incorporated in a display device, a mobile phone, an electronic computer, and the like.

[0003] The prior art will be described with reference to FIGS. 2 and 3. FIG. 2 is a plan view showing a part for explaining a conventional technique, and FIG. 3 is a partial cross-sectional view showing an AA cross section of FIG.

A description will be given of an example of a conventional structure in which a flexible insulating thin plate is used as a substrate for incorporating an electric device. As shown in the drawing, a wiring 2 formed of a conductor provided on a flexible and insulating thin plate substrate 1 is first prepared. It is natural that the wiring 2 has an arbitrary shape so as to embody the design.

The electric component 3 has a protruding electrode 4 provided on the lower surface thereof, and is connected to a wiring electrode 5 which is a part of the wiring 2. The connection method uses an anisotropic conductive film (hereinafter referred to as ACF) 7 having an area slightly larger than the occupied area of the electric component 3.
Is provided, and is then heat-pressed and fixed with the electric component 3. Further, a protective film 6 for the wiring 2 is provided so as to cover most of the entire substrate except for a region where the electric component 3 is provided.

The ACF is a film in which conductive particles are dispersed in an adhesive. An ACF is provided between an electrode to be connected, in this case, a projecting electrode 4 of the electric component 3 and a wiring electrode 5 which is a part of the wiring 2. Conductive particles (not shown) by sandwiching and heating and pressing
Are electrically connected via a wire, and are used for a method of fixing and holding the two electrodes 4 and 5 with an adhesive.

The method using the ACF is convenient for taking out electrodes such as electric parts provided with many electrodes at fine intervals. However, it has the following problems. 1) Foams when heated. 2) The density of the conductive particles contained in the adhesive layer of the ACF melted out and reduced.

To explain the problem 1), FIGS.
Bubbles 8 were shown inside. When the bubbles 8 are present between the wiring electrodes, for example, the size of the bubbles 8 changes due to an increase in temperature and processing, and as a result, the protrusion electrode 4 and the wiring electrode 5 are separated from each other, which affects reliability. Further, the presence of the bubbles 8 is a problem to be solved because external moisture directly affects the electrodes.

The air bubbles 8 sunk under the electric part 3 and fixed thereon serve as the above-mentioned peeling force. The problem of the moisture resistance due to the occurrence of is large.

In order to solve the problem 1), Japanese Patent Laid-Open No. 7-3
No. 7936 proposes an ACF bonder which can attach an ITO electrode and a TAB lead on a liquid crystal panel substrate without bubbles at a joint portion. This is a device for devising a device for attaching the ACF and moving it in a sliding contact, instead of simply holding down and attaching the device. In other words, this is a method in which a pressing portion provided for pressurization is formed in a streamline shape and generated bubbles are removed at the time of sticking.

To solve the problem 2), Japanese Patent Application Laid-Open No. 9-2
No. 44047 proposes a structure for suppressing the number of conductive particles flowing out from under the bumps of an IC when heating a ACF when mounting a driving IC in a flip-chip type liquid crystal display device. Specifically, as shown in FIGS. 2 and 3, there is disclosed a structure in which the wiring electrode 5 is provided with an outflow preventing wall which is smaller than the protruding electrode 4 to prevent the ACF from flowing out.

[0012]

SUMMARY OF THE INVENTION The present invention relates to the AC
When connecting and fixing an electric component to a substrate using F, 1) foaming occurs during heating. 2) The density of the conductive particles contained in the adhesive layer of the ACF melted out and reduced. It is intended to solve the problem described above or to make it a minor symptom.

ACF foaming cannot be completely eliminated. Although the cause of the foaming is unknown, a) It is considered that when the ACF is heated through a substrate or an electrical component to be connected and the ACF is indirectly heated, the uniformity is lost, and as a result, bubbles are generated. Have been. It is difficult to solve the problem with the ACF bonder alone. In particular, in a method in which heating energy from an electric component represented by a chip-on-film (hereinafter, referred to as COF) is applied to the ACF, it is impossible only by the degree of parallelism.

Further, it is not possible to completely prevent the ACF adhesive from flowing out when it is melted. The reason for this is that the width of each part is different, and the width of the ACF used in the form of a film is changed for each part and the optimum width cannot be attached. Therefore, an extra amount is eventually discharged in the heating and pressing process. As a result, some of the metal particles are discharged together therewith.

The present invention solves at least one of the above problems. It is another object of the present invention to provide a structure of a substrate that does not deteriorate the number of steps as compared with a conventional process operation method. Further, extra A in the direction controlled by the present invention
The purpose of the present invention is to provide a substrate that contributes to a reduction in cost by improving the yield by discharging CF.

[0016]

According to the present invention, a projecting electrode provided on the lower surface of an electric component and a wiring provided on a flexible insulating substrate are connected by thermocompression bonding via an anisotropic conductive film. In a substrate used for connection of a fixed electric device, a lead-out wall for introducing bubbles generated during thermocompression bonding and a melt of the binder to a position inside the position where the protruding electrode of the electric component comes into contact with and separated from the wiring. A substrate used for connection of an electric device.

According to the present invention, there is provided a substrate used for connection of an electric device, wherein the wiring and the lead-out wall are formed of a wiring material provided on a flexible insulating substrate.

Further, the present invention is characterized in that the lead-out wall is provided outside the electric component and a discharge portion of the lead-out wall is formed at a position separated from the wiring group constituting the wiring. Substrate.

[0019]

FIG. 1 is a plan view for explaining an embodiment of the present invention. The substrate used to connect the electric device according to the present invention is a flexible and insulating thin substrate 1
1, a wiring 12 is arranged, and an electric component 13 is electrically connected to a wiring electrode 15 provided at a position corresponding to a projecting electrode 14 provided on the electric component at a wiring end.

The substrate according to the present invention is generally provided with a protective film 16 having a large area. The protective film 16 is provided with an opening having an area slightly larger than a region where the electric component 13 is provided, and the electric component 13 is connected thereto via the ACF 17 from above. Since the ACF has been described in the section of the prior art, it is omitted in this section. Similarly, the conductive particles are omitted in the figure.

The feature of the present invention is as shown in FIG.
9 is provided. The lead-out wall 19 is a conductive metal provided on the thin plate substrate 1 and is made of the same material as the wiring 12. This material is defined as the same material even if copper foil is plated with gold or gold is not present on the lead-out wall 19. That is, any conductive portion of the material used for the wiring 12 is referred to as the material of the lead-out wall 19.

The shape of the lead-out wall 19 is located inside the tip of the wiring electrode 15 at a position where there is a separation distance that can prevent an electrical short circuit. Moreover, at least one discharge unit 20
have. The discharge unit 20 is suitably provided at a position where the wiring 12 is rough. Outgoing wall 19 according to the invention
The correlation between the discharge section 20 and the discharge section 20 is a versatile use in which a rectangular outlet wall 19 is formed and the discharge section 20 is designed to be arranged on both sides.

Specifically, the electric component 13 is 3 mm, 11 mm and 0.6 mm in length, width and thickness, respectively, and the opening of the protective film 16 is 3.25 mm and 12 m in length and width.
m and its thickness was 0.01 mm. The length, width, and thickness of the ACF were 3.5 mm, 13 mm, and 0.03 mm. The wiring 12 had a value of 80 μm in width and 15 μm in thickness, and had 120 wiring electrodes 15 at its tip and arranged along the long side. The protruding electrode 14 has a trapezoidal shape with a height of 14 μm, and naturally corresponds to the wiring electrode.

In the specific example described above, the ACF melts and flows out by about 15% in the thickness direction. The area inside the outlet wall is discharged to an area where the density of the flow wiring is coarse according to the outlet wall. The area outside the lead-out wall, that is, the area where the wiring group enters under the electric component is less than 10% of the entire area of the ACF, so that the outflow rate is about 15%, which is the same as the inside area. It is natural that the absolute amount of effluent is small.

If the entire bubble is generated uniformly, it is generated inside the outlet wall having a large absolute amount, and is pushed out from the discharge portion like a "punched bun" to prevent accidental accidental occurrence. In many cases, it is led to the specified area. On the other hand, the area of the wiring group that reaches the outside of the outlet wall, that is, the lower surface of the component, is affected by foaming only by 10% and is mostly processed by the outlet wall. Bubbles that are small and aggregated and become large can be described as mostly occurring inside the outlet wall and not affecting the outside.

[0026]

According to the present invention, an outlet wall having a discharge portion is provided under an electric component. This lead-out wall does not increase the man-hour in this step at all if a pattern in which the pattern of this portion is transferred to the same mask is used when wiring is formed by etching the thin plate substrate.

The material cost is a portion which is etched off as an unnecessary region when a wiring is formed by etching a copper foil, and this cost is not required.

Therefore, it can be said that the substrate is used for connecting an electric device having a structure in which the number of steps and the material cost do not change.

According to the present invention, the probability of foam remaining in a part of the ACF due to foaming in the outlet wall even if it becomes large in the outlet wall increases due to the “pressing bun” effect. The exit location is discharged from the discharge unit to a predetermined safe location. Moreover, naturally, the generation of bubbles is small outside the area surrounded by the outlet wall,
In particular, there is no effect between the wirings.

Regarding the fact that the conductive particles mixed in when the adhesive constituting the melted ACF flows out also flow out and the density is reduced, the outflow is divided into a large portion and a small amount in the outlet wall. As a result, the amount of the ACF flowing out of the outer wiring portion itself is small, so that only the conductive particles do not flow particularly large. Therefore, the difference between the density when the ACF is applied and the density when the ACF is completed is about -20% (meaning 80% at the time of application), and as is widely known, 20% or less at the time of application. It did not drop to 30%.

Further, the presence of the conductive particles is not necessary inside the outlet wall. That is, the necessary region is only a portion sandwiched between the protruding electrode and the wiring electrode. Therefore, the inside of the outlet wall satisfies the function as long as there is an effect of the adhesive.

[Brief description of the drawings]

FIG. 1 is a plan view for explaining the present invention.

FIG. 2 is a plan view for explaining a conventional example.

FIG. 3 is a sectional view taken along line AA of FIG. 2 for explaining a conventional example.

Continued on the front page F-term (reference) 5E319 AA03 AB05 AC03 BB16 CC61 GG20 5E336 AA04 BB01 BB12 BC28 CC34 CC55 CC58 DD13 EE08 GG12 GG30 5E338 AA01 AA12 BB61 CC01 CD11 EE11 EE33 EE51 5F044 KK03 KK09

Claims (3)

[Claims] An electric device in which a projection electrode provided on a lower surface of an electric component and a wiring provided on a flexible insulating substrate are connected and fixed by thermocompression bonding via an anisotropic conductive film. In the substrate, a lead-out wall for guiding bubbles generated at the time of thermocompression bonding and a melt of the binder is provided at a position inside the contact position of the protruding electrode of the electric component and separated from the wiring at a position inside. A substrate used to connect electrical devices. 2. The substrate used for connecting an electric device according to claim 1, wherein the wiring and the lead-out wall are formed of a wiring material provided on a flexible insulating substrate. 3. The electric device according to claim 1, wherein the lead-out wall is provided outside the electric component and a discharge portion of the lead-out wall is provided at a position separated from a wiring group forming the wiring. Substrate used for connection.