JPH0552062B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a film carrier mounting structure, and more particularly to a film carrier mounting structure connected using an anisotropic conductive film.

[Prior Art] When connecting, for example, a driving IC to a transparent conductive film such as ITO on a glass substrate, a method of connecting by a film carrier using an anisotropic conductive film is often used.

By the way, as a conventional film carrier mounting structure, the one shown in FIG. 5 is known.

FIG. 5 shows a cross-sectional view of a conventional film carrier mounting structure, in which a copper foil 3 constituting a conductor pattern is bonded onto a flexible insulating film 1 made of polyimide or the like with an adhesive 2. A finger-shaped inner lead bonding portion 6 is formed inside a device hole 5 formed in the flexible insulating film 1 for connection to the semiconductor element 4, and the semiconductor element 4 is connected here.

This film carrier 10 is applied onto a transparent conductive film 9 such as ITO formed on a glass substrate 8 of a liquid crystal display element, and an anisotropic conductive film 7 in which conductive particles such as metal particles are dispersed in an adhesive. They are joined by thermocompression bonding.

[Problems to be Solved by the Invention] However, the conventional film carrier mounting structure described above has the following problems.

In recent years, liquid crystal display elements have come to be used as large-screen displays instead of conventional CRTs. For example, liquid crystal displays with 640 x 400 dots or more are being used in personal computers, word processors, etc. I'm getting used to it. In addition, larger screens,
There is a growing demand for higher definition and colorization.

The driving IC for these large-screen LCD displays
Recently, a mounting structure in which an anisotropic conductive film is mounted using a film carrier method, as described above, has become popular. As anisotropic conductive films, for example, CP-2132 manufactured by Sony Chemical and AC5052 manufactured by Hitachi Chemical are known, and their connection resolution is 5 lines/mm.
(200 μm pitch) is possible.

Incidentally, in response to demands for larger screens, higher definition, and more color, the pixels of liquid crystal displays are required to have higher density and narrower pitch. When increasing the screen size, the load impedance of the transparent conductive film on the glass substrate of the liquid crystal display increases, causing delays in signals from the driving IC, resulting in a decrease in display quality. In order to prevent such deterioration in display quality, as shown in FIG. 6, a method is adopted in which the pattern of the transparent conductive film 9 is taken out from the center of the screen on both sides of the glass substrate 8, and the film carrier 10 of the driving IC is connected to both sides. is considered. In addition, for high definition and colorization, the pixel pitch must be extremely narrow, for example, 8 pixels/mm (125μ
m pitch) or 10 lines/mm (100 μm pitch), but as mentioned above, currently, 5 lines/mm (100 μm pitch) is required to implement a film carrier with an anisotropic conductive film.
Since the limit is about mm (200μm pitch),
For example, as shown in FIG. 7, the pattern of the transparent conductive film 9 on the glass substrate 8 is taken out alternately in a staggered manner on both sides of the glass substrate 8, the pattern pitch is halved, and the film carrier 10 of the driving IC is placed on both sides. A method of connecting the two is being considered.

However, when attempting to mount the driving ICs on both sides of the glass substrate 8 in this way, as shown in FIG. Assuming that the liquid crystal pixel driving output is designed to scan in the direction of the arrow from 1 as shown in the figure, the same driving IC 11 is connected to the other side of the glass substrate 8 (see Figure 9). When mounted on the right side), the output for driving the liquid crystal pixel of the driving IC 11 becomes as shown by the arrow in the figure.
The scanning direction is reversed on both sides of the glass substrate 8, making it impossible to use the same driving IC. For this reason, it is necessary to design the driving IC 11 to have an output that can scan in both directions, or to use two different types of driving ICs. For driving (seeds required)
Since an IC was required, there were problems such as an increase in the cost of the drive IC and a complicated film carrier mounting process.

Furthermore, when the mounting method shown in FIG. 5 described above is used, when the anisotropic conductive film 7 is thermocompression bonded, the flexible insulating film 1 made of polyimide or the like is heated to 150 to 250°C by the thermocompression hot press. Due to the difference in coefficient of thermal expansion between the flexible insulating film 1 and the glass substrate 8, the flexible insulating film 1 expands thermally during thermocompression bonding and contracts after thermocompression bonding. The problem is that the anisotropic conductive film 7 is misaligned and stress is applied to the anisotropic conductive film 7, leading to an increase in connection resistance and a decrease in connection strength, which reduces the reliability of film carrier mounting. It was hot.

In addition, during thermocompression bonding, the anisotropic conductive film is actually heated in the range of 130 to 180℃ (varies depending on the product of each company).
It is desirable to apply heat with an accuracy of approximately ±5°C, but in the conventional mounting structure, heating is performed by a hot press for thermocompression via the flexible insulating film 1 of the film carrier 10, so this flexible insulating film acts as an insulator,
There were problems in that it was difficult to control the heat applied to the anisotropic conductive film and it took a long time to heat it.

The present invention eliminates the drawbacks of the conventional example and provides a drive
This makes it possible to mount the IC film carrier on both sides of the board, and prevents deterioration in connection reliability due to misalignment and stress caused by differences in thermal expansion coefficients between the flexible insulating film of the film carrier and the connecting board. Moreover, it is an object of the present invention to provide a film carrier mounting structure that facilitates heating temperature control during thermocompression bonding and shortens heating time.

[Means for Solving the Problems] The bonded structure of the present invention connects the first group of conductive films provided on the first film carrier to the first of the plurality of conductive films provided on the element substrate. A third group of conductive films is electrically connected to a first semiconductor disposed on one of the opposing sides of the element substrate, and a third group of conductive films is disposed on a second film carrier. A fourth group of conductive films among the plurality of conductive films provided on the element substrate and a second semiconductor disposed on the other side of the opposing poles of the element substrate are electrically connected via a conductive film. a first group and a second group of conductive films extending from one end of the first group and a third group of conductive films, respectively; The first group of finger-shaped conductive films and the second group of conductive films are connected to each other through an anisotropic conductive film so that the first semiconductor is in a face-up state. The second group of finger-shaped conductive films and the fourth group of finger-shaped conductive films are connected to each other through an anisotropic conductive film such that the second semiconductor is electrically connected and the second semiconductor is in a face-down state. and are electrically connected to each other.

[Examples] The present invention will be described in detail below with reference to Examples.

FIG. 1 shows an embodiment of the film carrier mounting structure according to the present invention.
A copper foil 3 having a thickness of 35 .mu.m is bonded to a flexible insulating film 1 made of a material such as 35 .mu.m thick with an adhesive 2, and a conductive pattern is formed by etching.

This conductor pattern is formed to extend to the device hole 5, and forms a finger-shaped inner lead bonding part 6 for bonding with the semiconductor element 4 in a face-up state, and is used for thermocompression bonding of gold bumps, etc. A semiconductor element 4 is sometimes connected.

Similarly, finger-shaped outer lead bonding portions 21 are formed extending from the flexible insulating film 1.

The outer lead bonding part 21 and the transparent conductive film 9 made of ITO or the like on the glass substrate 8 of the liquid crystal display element are bonded together using an anisotropic conductive film 7 made by dispersing conductive particles such as metal particles in an adhesive (for example, Hitachi Polyimide (for example, Upilex R manufactured by Ube Industries)
7.5 μm)
are arranged above the outer lead bonding part 21 and bonded by thermocompression bonding to form a film carrier mounting structure.

Note that it is desirable that the area of this flexible insulating film 22 be approximately the same size as that of the anisotropic conductive film 7. This flexible insulating film 22 prevents the adhesive of the anisotropic conductive film 7 from adhering to the head part of the thermocompression hot press during thermocompression bonding, and
It works to prevent the anisotropic conductive film from absorbing moisture and reducing reliability after thermocompression bonding.

When the mounting structure of the film carrier is formed in this way, as shown in FIG.
Connect the film carrier 1 to the inner lead bonding part 6 with the face down.
It is possible to turn the entire 0 upside down and mount it on the glass substrate 8. Note that each part in FIG. 2 is the same as in FIG. 1.

Therefore, in the film carrier mounting structure of the present invention, as shown in FIG.
When mounting film carriers 10 on both sides of
The film carrier 10 to be mounted on the left side of the glass substrate 8 in FIG. 6 is mounted as shown in the cross-sectional view in FIG. 1 and the plan view in FIG. It can be implemented as shown in the cross-sectional view of the figure and the plan view of FIG.

Here, in FIGS. 3 and 4, for driving
Considering the scanning direction of the output for driving the liquid crystal pixels of the IC 11, in Fig. 3 it is scanned in the direction of the arrow 1 as in the conventional example, but in Fig. 4, as is clear from the figure, the film carrier 10 is turned over. Even if the same driving IC 11 and film carrier 10 are used, the scanning direction of the liquid crystal pixel driving output will be in the direction of the arrow 1 from 1 as shown in the figure, and will be mounted on the left and right sides of the glass substrate. Even if it is implemented, the scanning direction will not change.

Furthermore, in the film carrier mounting structure of the present invention, as described above with reference to FIG. Furthermore, if a material is used that is so thin that its thermal expansion can be ignored, the anisotropic conductive film will not be misaligned or stressed due to thermal expansion and contraction during thermocompression bonding.

Further, in the present invention, a flexible insulating film 2 that is sufficiently thinner than the flexible insulating film 1 used in the film carrier 10 is used in the thermocompression bonding part.
2, the temperature from the heating head of the thermocompression hot press is easily transmitted to the anisotropic conductive film, the heating temperature can be controlled relatively easily, and thermocompression bonding can be carried out in a short time.

In the above embodiments, the film carrier and the glass substrate of the liquid crystal display element were explained, but it is not limited to liquid crystal display elements, but can also be applied to driving ICs for long thermal heads, contact type image sensors, EL display elements, etc.
The same can be used for implementation.

In addition, the method of thermocompression bonding using a flexible insulating film that is sufficiently thinner than the flexible insulating film is as follows.
It can be used not only for the outer lead bonding part of a film carrier, but also for bonding flexible substrates using other flexible insulating films and printed boards such as glass substrates and glass epoxy/phenol.

FIG. 10 shows another embodiment in which the present invention is applied to a contact type image sensor. Even when mounting an IC on a conventional contact-type image sensor using a film carrier, if outer lead bonding is performed using an anisotropic conductive film as described in the example above, the lead bonding rate will be 5 wires/mm (200 μm). Since it can only be mounted at a density of about 300 yen (Pitch), it was not possible to increase the density of the sensor section too much. However, as shown in FIG. 10, the density of the sensor section can be increased by mounting ICs on both sides of the glass substrate using the present invention.

[Effects of the Invention] As explained above, by using the film carrier mounting structure according to the present invention, it is possible to mount the same semiconductor element and film carrier with the front and back sides of the film carrier reversed. It can be mounted without changing the scanning direction of the output with respect to the substrate to be bonded.

Therefore, the cost of IC does not increase and the process of mounting the film carrier does not become complicated.

Further, since the anisotropic conductive film is not displaced or stressed due to the difference in thermal expansion coefficient between the flexible insulating film and the glass substrate, it is useful for improving the reliability of the connection portion.

Furthermore, since temperature is more easily transmitted to the anisotropic conductive film during thermocompression bonding than in a hot press for thermocompression bonding, the thermocompression bonding temperature can be controlled easily and in a short time.

[Brief explanation of the drawing]

1 and 2 are cross-sectional views showing a mounting structure of a film carrier according to the present invention. 3 and 4 are plan views showing the output scanning direction of an IC when using the film carrier mounting structure according to the present invention. FIG. 5 is a sectional view showing a conventional example of a film carrier mounting structure using an anisotropic conductive film. FIGS. 6 and 7 are plan views showing how the film carrier is mounted on the glass substrate. FIGS. 8 and 9 are plan views showing the output scanning direction of an IC when a conventional film carrier mounting structure is used. FIG. 10 is a plan view showing another embodiment of the present invention. 1...Flexible insulating film, 2...Adhesive material,
3...Copper foil, 4...Semiconductor element, 5...Device hole, 6...Inner lead bonding part, 7...
Anisotropic conductive film, 8... wiring board (glass substrate),
9...Transparent conductive film, 10...Film carrier,
DESCRIPTION OF SYMBOLS 11...Drive IC, 21...Outer lead bonding part, 22...Flexible insulating film.

Claims (1)

[Claims] 1. A second group of conductive films of a plurality of conductive films provided on an element substrate and a conductive film of the element substrate are connected to each other through a first group of conductive films provided on a first film carrier. electrically connected to a first semiconductor disposed on one of the opposing sides, and via a third group of conductive films provided on the second film carrier;
A fourth group of conductive films among the plurality of conductive films provided on the element substrate is electrically connected to a second semiconductor disposed on the other side of the opposing poles of the element substrate. A connecting structure, wherein the first and second film carriers each have a first group and a second group of finger-shaped conductive films extending from one end of the first group and third group of conductive films, respectively. and the first group of finger-shaped conductive films and the second group of conductive films are electrically connected via an anisotropic conductive film so that the first semiconductor is in a face-up state. and the finger-shaped conductive films of the second group and the fourth group are electrically connected via the anisotropic conductive film so that the second semiconductor is in a face-down state. A connection structure characterized by: 2. The connected structure according to claim 1, wherein the element substrate is a glass substrate for forming a display element. 3. The connected structure according to claim 2, wherein the display element is an element using liquid crystal. 4. The connected structure according to claim 1, wherein the element substrate is a glass substrate for configuring an image sensor. 5. The connected structure according to claim 1, wherein the second group of conductive films and the fourth group of conductive films are alternately wired on the element substrate. 6. The connected structure according to claim 1, wherein the second group of conductive films and the fourth group of conductive films are alternately wired on the element substrate. 7. A patent claim in which the conductive films of the second group are wired on one side in the plane of the element substrate, and the conductive films of the fourth group are wired on the other side in the plane of the element substrate. The connected structure according to item 1.