JP2985584B2 - Bend mounting type TAB film carrier and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a TAB (Tape Automat).
The present invention relates to a structure of a film carrier suitable for application to element mounting by an ed bonding technique, particularly to a structure of a film carrier for bending mounting and a method of manufacturing the same.

[0002]

2. Description of the Related Art The TAB technique is an excellent mounting method that meets the demands for thinning, multi-pin, and automated assembly of circuit packages, and is widely used in production sites of semiconductor integrated circuit devices and the like. In TAB technology, for example, FIG.
A film carrier having the structure shown in FIG. In the figure, reference numeral 1 denotes a base film 1 made of, for example, a flexible insulating film material made of polyimide. Openings required for mounting elements, such as sprocket holes 2, device holes 3, and outer lead holes 4, are perforated. Have been.
The conductive leads such as the inner leads 6 and the outer leads 7 are not shown in detail, but after a metal foil (usually an electrolytic copper foil) is attached to the required surface of the base film 1 via an adhesive layer 8, It is formed by performing pattern etching. The surface of each conductive lead is usually plated with gold, tin, or solder at a necessary portion to make the bonding operation easy and reliable.

The film carrier shown in FIG. 1 is designed for mounting a semiconductor integrated circuit element for driving a liquid crystal. The output signal outer leads 7a are provided on the upper half of the base film 1, and the input signals are provided on the lower half. Outer leads 7b are respectively formed. Although not shown in detail, the mounted circuit element is bonded to the inner lead 6 in the device hole 3. In the film carrier on which the mounted circuit element is mounted, the output signal outer lead 7a faces the electrode terminal group on the periphery of the liquid crystal circuit board, and is connected to the electrode terminal using, for example, an anisotropic conductive adhesive. Implement by The input signal outer leads 7b are connected to electrode groups on a predetermined input circuit board by, for example, a soldering technique.

In recent years, the mounting of a semiconductor integrated circuit element for driving a liquid crystal has been required to further reduce the mounting volume with the miniaturization and high density of the device. For example, as shown in FIG. The method of bending and mounting at a right angle at the end (bending mounting) is becoming mainstream. 4, reference numeral 9 denotes a mounted circuit element mounted on a film carrier, and reference numeral 11 denotes an anisotropic conductive adhesive layer for connecting the film carrier to the liquid crystal circuit board 10.

In the bent mounting type film carrier, in order to enable the output signal outer leads 7a to be bent at a very small radius, as shown in FIGS. 1 and 2, prior to the bonding of the copper foil to the base film 1, It is usual to provide a slit 5 for bending mounting of a predetermined width by piercing and removing a part (scheduled portion to be bent) of the film together with the adhesive layer 8, but such a slit is formed. In this case, since there is no longer a member functioning as a reinforcing member for the outer lead 7a, mechanical stress during mounting and stress due to thermal cycling concentrate on the outer lead 7a in the bent mounting slit 5 and cracks or breaks. Cause. For this reason, as described in, for example, Japanese Patent Application Laid-Open No. Hei 4-91450, there has been proposed a method of preventing stress concentration on outer leads by processing a base film at a portion to be bent and leaving the base film thin. However, this method has another problem in that the production cost is significantly increased because chemical etching must be used for processing the base film.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a novel structure of a TAB film carrier for bending mounting which has improved bending resistance of conductive leads such as outer leads, and such a film carrier. It is to propose a method for manufacturing a.

[0007]

In order to solve the above-mentioned problems, the present invention uses a base film in which a slit for bending mounting is formed in advance, and bridges the slit with the base film. After forming an adhesive layer on the surface, by punching the base film with the adhesive layer, other openings required for element mounting, such as device holes and outer lead holes, are formed. A metal foil is attached via an adhesive layer formed on the film surface, and a predetermined pattern etching process is performed on the metal foil to form a group of conductive leads such as inner leads and outer leads. The adhesive layer in the bent mounting slit portion is left as it is, and is used as a backing reinforcing member for the conductive lead group in a portion straddling the slit.

The above-mentioned adhesive layer can be formed by using an adhesive generally used for producing this kind of film carrier, for example, an epoxy-based adhesive.
However, in the case of the present invention, since the adhesive layer for adhering the metal foil (conductive lead) to the base film is also used as a backing reinforcing member for the conductive lead, the adhesive layer has a breaking elongation rate. It is desirable to use an adhesive that forms a flexible thermosetting film that is at least 50% or more. According to the results of the prototype experiment of the present inventors,
Polyimide adhesives are highly preferred adhesives for this purpose.

[0009]

EXAMPLE A base film composed of a polyimide film material (trade name: Kapton V) manufactured by Toray Dupont and having a thickness of 75 μm was prepared, and the film was subjected to press working to form sprocket holes and slits for bending mounting. First, it was perforated. On the other hand, a release film made of a polyester resin is separately prepared, and a solution of a thermosetting adhesive is applied on the film and dried, and then the adhesive surface is attached to the base film (the slit portion for bending mounting is removed). ) To form a double-layered film having an adhesive layer having a thickness of 20 μm in the middle.

[0010] Next, by pressing the double-structured film thus formed, the device hole and the outer lead hole are pierced, and the surface of the adhesive layer is peeled off while releasing the release film. 35 μm thick
The electrolytic copper foil was completely adhered on the base film by sticking the electrolytic copper foil and heating the whole to cure the adhesive layer. Finally, the electrolytic copper foil was subjected to a pattern etching process to obtain a folded mounting type TAB film carrier having the appearance structure shown in FIG. This film carrier is similar to the conventional film carrier in that the inner leads 6 and the outer leads 7 are provided on the base film 1 via the adhesive layer 8,
As shown in FIG. 3, it differs from the conventional film carrier in that the output signal outer lead 7a at the portion straddling the bent mounting slit 5 is reinforced with an adhesive layer 8 bridging the slit. The width and the pitch of the output signal outer lead 7a at the portion straddling the bending slit 5 were set to 100 μm and 200 μm, respectively.

The present inventors have used two types of bent mountings manufactured by using the above-mentioned method by using an epoxy-based adhesive and a polyimide-based adhesive as a thermosetting adhesive for forming the adhesive layer 8. A bending test was performed on the mold film carrier. For performance comparison, a folded mounting type film carrier having the conventional structure shown in FIG. 2 was separately manufactured and subjected to the same bending test. In the bending test, as shown in FIG.
(Curvature radius of the corner: 0.5 mm), and alternately 90 degrees on the outer lead 7a side and the base film 1 side.
The number of times until the outer lead 7a was broken was examined with one reciprocal bending and one reciprocal bending. Table 1 shows the test results.

[0012]

[Table 1]

As is clear from Table 1, the film carrier of the present invention in which the adhesive layer at the slit portion for bending mounting is left as a backing reinforcing member is a film carrier having a conventional structure without an adhesive layer at the slit portion. The bending resistance was significantly improved in comparison. In particular, it was found that Sample 2 in which the adhesive layer was formed using a polyimide-based adhesive did not break the adhesive layer itself, and had extremely good bending resistance.

[0014]

According to the present invention, the bending resistance of the folded mounting type TAB film carrier can be remarkably improved by a very simple structure or manufacturing method.

[Brief description of the drawings]

FIG. 1 is a plan view showing a general external structure of a bent mounting type TAB tape carrier.

FIG. 2 is a cross-sectional view for explaining the structure of a conventional bent mounting type TAB tape carrier (however, FIG. 2A is AA of FIG. 1).
(B is a cross-sectional view taken along the line BB in FIG. 1).

FIG. 3 is a cross-sectional view for explaining an embodiment of the bent mounting type TAB tape carrier according to the present invention (however, FIG. 3A is a cross-sectional view taken along the line AA in FIG. 1; FIG. Is B- in FIG.
Sectional view shown along line B).

FIG. 4 is a cross-sectional view for explaining a mounting mode of the bent mounting type TAB tape carrier.

FIG. 5 is a sectional view for explaining a bending test performed by the present inventors.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Base film, 2 ... Sprocket hole, 3 ... Device hole, 4 ... Outer lead hole, 5 ... Bending mounting slit, 6 ... Inner lead, 7 ... Outer lead, 8 ... Adhesive layer, 9 ... Circuit to be mounted Element: 10: liquid crystal circuit board, 11: conductive adhesive layer, 12: clamp support

Continuation of front page (58) Field surveyed (Int. Cl. ⁶ , DB name) H01L 21/60 311

Claims (4)

(57) [Claims] 1. A base film in which openings required for mounting elements such as device holes and outer lead holes are provided in a flexible insulating film having sprocket holes.
An adhesive layer formed to cover the required surface of the base film, and a conductive material such as an inner lead and an outer lead formed by performing pattern etching on a metal foil attached to the base film via the adhesive layer. The base film is provided with a slit (hereinafter, referred to as a "bending mounting slit") that is formed of a lead group and that enables the conductive lead group to be mounted by bending (hereinafter, referred to as "bending mounting slit"). In the TAB film carrier, the adhesive layer is formed on the base film in such a manner as to bridge the slit for bending mounting, and a conductive lead group in a portion straddling the slit bridges the slit. A foldable mounting type TAB film carrier characterized by being reinforced by backing. 2. The fold according to claim 1, wherein the adhesive layer is made of an adhesive constituting a flexible thermosetting film having a breaking elongation of at least 50% or more. Curved mounting type TAB film carrier. 3. The folded mounting type TA according to claim 2, wherein a polyimide adhesive is used as the adhesive.
Film carrier for B. 4. A bent film mounting slit is formed in a base film made of a flexible insulating film having sprocket holes, and an adhesive layer is formed on the base film in such a manner as to bridge the slit. In the base film with the agent layer, other openings required for element mounting such as device holes and outer lead holes are provided, and then, a metal foil is attached to the base film via the adhesive layer, Forming a conductive lead group such as an inner lead and an outer lead by performing a pattern etching process on the TAB film carrier.