JPH098083A - Film carrier for semiconductor integrated circuit - Google Patents

Abstract

PURPOSE: To improve flatness while using a thin film, by making a film whose thickness is less than or equal to a specified value an insulating substrate, and forming, on the film, a pattern for reinforcement in the film width direction, so as to stretch wider than or equal to at least a specified percentage of the film width. CONSTITUTION: An insulating substrate is a film whose thickness is at most 40μm, and a wiring pattern composed of a metal layer bonded to a single surface of the film is formed. On the film, a pattern for reinforcement is formed in the film width direction, so as to stretch wider than or equal to at least 80% of the film width. A device hole 6 is divided into two parts, and a pattern 9' for reinforcement is formed on the central insulating film 10. Since the pattern for reinforcement is formed also in the device hole part where an IC is mounted, the flatness of a film carrier is maintained at the time of IC mounting, and its operation can be more facilitated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a semiconductor integrated circuit (hereinafter,
The present invention relates to a film carrier for IC), and more specifically to a film carrier using a thin film as an insulating substrate film.

[0002]

2. Description of the Related Art A film carrier method, which is one of the mounting methods for ICs, is disclosed in Japanese Examined Patent Publication No. 47-3206, "Electronic Technology" Vol. 16, No. 11, 93-97, published by Nikkan Kogyo Shimbun.
(1974), Nikkei McGraw-Hill, Nikkei Electronics, August 12, 1974, pages 121-136,
Published by Nikkei McGraw-Hill "Nikkei Electronics" 197
The basic technology is shown in the June 6, 1st issue, pp. 60-67, etc. These are, for example, Mini-Mod method (trademark of US General Electric Company), chip carrier method, tape automated bonding (TAB) method. These methods can improve productivity and reduce manufacturing costs.

A conventional film carrier is a polyimide film having a thickness of 50 μm or more as a substrate material,
Generally, a polyester film, a glass sheet impregnated with an epoxy resin, etc., and a copper foil bonded to these long sheets and pattern-etched are generally used. The film carrier is for mounting the driver IC of LCD,
Widely used in multi-pin thin-type applications such as gate array TAB packages, which are multi-pin LSI chips, and thermal heads.

There are further demands for film carriers for finer pitches and cost reductions, and there are proposals for an aromatic polyamide (hereinafter referred to as aramid) film having a low coefficient of thermal expansion as an insulating substrate, and an excellent machine for aramid films. It has been attempted to use a thinner film as an insulating substrate because of its physical characteristics. For LCD applications,
The so-called slim TAB in which the shape of the IC is a thin rectangle and the inner leads and the outer leads are provided in parallel on both sides of the IC is performed in order to reduce the outer dimensions of the liquid crystal panel. However, it has been found that the flatness of the film carrier is impaired when the thin film is used as the insulating substrate as described above.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a film carrier for semiconductor mounting, which has excellent flatness while using a thin film as an insulating substrate.

[0006]

Means for Solving the Problems As a result of intensive studies for achieving the above object, the present inventors have found that the cause of impairing the flatness is due to curing shrinkage of the adhesive. The present invention has been made by further studying a method for overcoming the above problem. That is, the object of the present invention is to have a thickness of 40μ.
On a film in which a film having a thickness of m or less is used as an insulating substrate, and a wiring pattern made of a metal layer adhered to one side of the film is provided, and between the wiring patterns and / or the device hall is divided in the length direction. Is provided with a reinforcing pattern covering at least 80% or more of the width of the film in the width direction of the film.

[0007]

The details of the present invention are explained below with reference to a schematic view of a film carrier. FIG. 1 shows a schematic structure of a conventional film carrier, and one wiring pattern is formed from (a) to (b). Wirings 2 made of metal such as copper foil are provided on the insulating substrate film 1, and the wirings include inner leads 3 used for connection with ICs, outer leads 4 used for connection with input / output circuits, etc. Is provided. The insulating substrate film is provided with a sprocket hole 5, a device hole 6, an outer lead hole 7, and the like.

FIG. 2 is a cross-sectional view of the portion A of the film carrier of FIG. 1, in which the wiring 2 is installed on the insulating substrate film 1 with the adhesive layer 8 interposed therebetween. Since the copper foil that should support the dimensional distortion with the insulating substrate film is divided as the wiring 2, the film carrier is deformed. FIG. 3 shows a schematic plan view of the film carrier of the present invention. A reinforcing pattern (hereinafter referred to as a reinforcing pattern) 9 is provided between each wiring pattern. FIG. 4 shows a cross section of the B part of the film carrier of FIG. 3, and the modification seen in FIG. 2 showing the cross section of the conventional film carrier is different from the modification shown in FIG. Of the adhesive layer 8 is continuously installed over almost the entire width of the adhesive layer 8 and supports the distortion generated by the curing shrinkage of the adhesive layer 8, so that no deformation occurs.

FIG. 5 is a plan view of a film carrier showing another embodiment of the present invention. In this example, the device hole 6 is divided into two, and the reinforcing pattern 9'of the present invention is installed on the insulating substrate film 10 at the center thereof. In this example, since the reinforcing pattern is also installed in the device hole portion where the IC is mounted, the flatness of the film carrier is maintained during IC mounting, and the operation can be further facilitated. In this embodiment, the reinforcing pattern 9 provided between the wiring patterns may be omitted.

In practicing the present invention, in the embodiment of the present invention shown in FIGS. 3 and 5, the reinforcing patterns 9 provided between the wiring patterns may be appropriately provided even if they are provided between the respective patterns. It may be thinned out at regular intervals. The insulating substrate used in the present invention is a film having a thickness of 40 μm or less. By using a thinner film than before, the cost of the insulating substrate can be reduced, and the flexibility of the film carrier is increased, so that various applications in mounting ICs can be achieved. And advantages can be expected.

Also for the copper foil forming the wiring, conventionally used copper or copper-based alloy may be used. The thickness may also be arbitrarily selected from the design of wiring density and the like. The film used in the present invention is
The film carrier is often heated during the manufacturing process, IC mounting, and liquid crystal panel mounting, preferably 200 ° C.
The film has a heat shrinkage of 0.1% or less and is represented by heat resistance.

The strength of the film is 25 kg / mm ²
As described above, it should preferably be 30 kg / mm ² or more, and it is preferable in order to prevent the film from being damaged during the film carrier manufacturing process, work such as IC mounting and liquid crystal panel mounting. As for the elastic modulus of the film, the thickness of the film used is thinner than conventional ones, so unnecessary deformation due to the force applied in the process of manufacturing and mounting the film carrier is prevented, and the wiring formed on the film is not destroyed. To prevent this, 600kg / mm ² or more, and even 800kg / mm ²
The above is preferable. Furthermore, the elongation of the film is 10 to 100.
% Is preferable.

The characteristics of these films should be satisfied in both the longitudinal direction and the width direction. Depending on the wiring pattern of the film carrier, they do not necessarily have to be the same, but it is preferable to select a so-called balanced type in which the characteristics in the longitudinal direction and the width direction are as close as possible. The film used in the present invention may be a polyester film such as polyethylene terephthalate or polyethylene naphthalate because it is inexpensive, but as a film satisfying the above more preferable characteristics, a film made of an aramid resin or a polyimide resin is used. Some can be used.

The aramid resin used in the present invention is substantially composed of a unit selected from the group consisting of the following constitutional units. —NH—Ar ₁ —NH— (A) —CO—Ar ₂ —CO— (B) —NH—Ar ₃ —CO— (C) where Ar ₁ , Ar ₂ and Ar ₃ are at least one aromatic ring. And may be the same or different, and typical examples thereof include those of the following general formula.

[0015]

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In addition, those in which a part of hydrogen atoms on the aromatic ring are substituted with a halogen group, a nitro group, an alkyl group, an alkoxy group or the like are also included. Also, X is -O-,
_{-CH 2 -, - SO 2 -} , - S -, - CO- , and the like.
In particular, an aramid resin in which 80 mol% or more of all aromatic rings are bonded in the para position is preferable for producing the film used in the present invention.

The polyimide resin used in the present invention is one having at least one aromatic ring and at least one imide group in the repeating unit of the polymer and is represented by the following general formula (1) or (2). It is what is done.

[0018]

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Here, Ar ₄ and Ar ₆ contain at least one aromatic ring, and two carbonyl groups forming an imide ring are bonded to adjacent carbon atoms on the aromatic ring. This A
r ₄ is derived from an aromatic tetracarboxylic acid or its anhydride. A typical example is one represented by the following general formula. Wherein Y is, -O -, - CO -, - CH 2 -, -
S -, - SO ₂ - and the like.

[0020]

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Ar ₆ in the above (2) is derived from tricarboxylic acid anhydride or its halide. Ar ₅ and Ar _{7 in} (1) and (2) include at least one aromatic ring and are derived from aromatic diamine and aromatic isocyanate. Representative examples of Ar ₅ or Ar ₇ include those represented by the following general formula.

[0022]

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Here, one of the hydrogen atoms on the ring of these aromatic rings is
Part is halogen group, nitro group, alkyl group, alkoxy
It also includes those substituted with a group. Z is -O-,-
CH ₂-, -S-, -SO₂-, -CO- and the like. Special
, Ar_Five, Ar₇More than 80% of the
The polyimide resin, which is an incense ring, is used in the present invention.
It is preferable for producing rum.

Further, the aramid resin or polyimide resin of the present invention contains a lubricant, an antioxidant, other additives, and other polymers as long as the physical properties of the film are not impaired and the object of the present invention is not impaired. It may be. The method for producing the film of the present invention is not particularly limited, and a production method suitable for each resin may be employed.

As for the aramid resin, if it is soluble in an organic solvent, it is polymerized directly in a solvent, or once the polymer is isolated and then redissolved to prepare a solution, which is then prepared by a dry method or a wet method. Be filmed. Further, those which are hardly soluble in organic solvents such as polyparaphenylene terephthalamide (hereinafter referred to as PPTA) are dissolved in concentrated sulfuric acid or the like to form a solution, and then formed into a film by a dry-wet method or a wet method.

In practicing the present invention, aramid resin tends to have a large dimensional change due to moisture absorption due to affinity of amide bond with water. Therefore, it is necessary to pay particular attention to control of humidity expansion coefficient of aramid resin film. is there. As a method for controlling the humidity expansion coefficient of the aramid resin film, a method of introducing a Cl group, a NO ₂ group or the like into the main chain of the polymer, a method of sufficiently heat treating the film to promote crystallization, and a film are constituted. Any method such as a method of selecting the type and amount of the binding metal ion to the COOH group at the terminal group of the aramid molecule can be used.

On the other hand, with respect to the polyimide resin, tetracarboxylic acid anhydride and aromatic diamine are reacted in an organic solvent to form a polyamic acid, and this solution is used as it is or after once subjected to a ring-closing treatment to form a polyimide, the solvent is reused. To obtain a solution, which is formed into a film by a dry method or a wet method. In the dry method, the solution is extruded from a die, cast on a support such as a metal drum or an endless belt, and the drying or imidization reaction proceeds until the cast solution forms a self-supporting film.

In the wet method, the solution is extruded directly from a die into a coagulating liquid, or cast on a metal drum or an endless belt as in the dry method, and then guided into the coagulating liquid and coagulated. Next, these films are washed with solvents and inorganic salts in the films and subjected to processes such as stretching, drying and heat treatment.

The substrate film used in the present invention contains a lubricant, a coloring agent such as a dye or a pigment, a flame retardant, an antistatic agent, an antioxidant and other modifiers, which do not contradict the purpose of the present invention. As long as it is included. The film carrier of the present invention uses the above-mentioned heat-resistant film as a substrate, and a wiring / wiring pattern made of a metal layer such as copper is laminated on one or both sides of the film. Usually, the substrate film and an adhesive are applied. After that, the sprocket hole and, if necessary, the device hole are punched, a metal layer is laminated, and patterning is performed by etching. Copper foil is usually used as the metal layer, but as a special layer, the coefficient of linear expansion is 8
It is also possible to use an alloy containing iron-nickel as a main component, a metal having a low linear expansion coefficient such as tantalum or molybdenum having a low linear expansion coefficient of x10 ^-6 mm / mm / ° C or less, and particularly a linear expansion such as a PPTA film. In combination with a substrate film having a low rate, there is an advantage that the inner leads and thermal expansion during IC mounting are small.

The substrate film and the metal are usually laminated with an adhesive such as an epoxy adhesive, but the adhesive is not particularly limited. The film carrier of the present invention is inner lead bonded to an IC by a usual method such as thermocompression bonding. In the case of double-sided type, the front side is
It is also possible to bond the wiring pattern on the back side to the wiring on both the front and back sides through a through hole by a usual method. (Method of measuring characteristics) The method of measuring characteristic values according to the present invention is as follows. (1) Method for measuring film thickness, strength, elongation and elastic modulus The film thickness is measured with a dial gauge having a measuring surface with a diameter of 2 mm.

The strength, elongation, and elastic modulus were measured using a constant-speed elongation type strong elongation measuring machine with a measuring length of 100 mm and a pulling speed of 50 m.
It is measured in m / min. (2) Method of measuring heat shrinkage A sample piece of 2 cm × 5 cm is cut out from a film and 4c
The mark is made by making a mark with a knife at intervals of m.
After leaving for 72 hours in an atmosphere of 5% RH, the distance between the labels was read and measured with a microscope, and then left in a hot air oven at 200 ° C. for 2 hours without restraining, then again at 23 ° C. and 55% RH. After leaving for 72 hours in the atmosphere of
The distance between the labels was read and measured with a microscope.

[0032]

Reference Example A preferred method for producing a PPTA film for carrying out the present invention is shown below. The characteristics of the film are
(Value in the lengthwise direction)-(Value in the width direction) Concentration 9
60% ηinh = 6.1 of PPTA was added to 9.5% concentrated sulfuric acid.
A stock solution having a polymer concentration of 12% was prepared by dissolving at 0 ° C. The stock solution was degassed under vacuum while maintaining it at 60 ° C. Pass the filter from the tank, send the liquid with a gear pump,
From a T-die having a slit of 0.4 mm x 750 mm, cast a dope on a tantalum belt, blow air with a relative humidity of about 5% and a temperature of about 105 ° C, and cast the casting dope with optics, etc. The solution was annealed and introduced into water at 5 ° C. with the belt to solidify. The coagulated film is then peeled off from the belt and washed with warm water at about 30 ° C, then 0.5% NaOH.
The solution was neutralized with an aqueous solution, further washed with water at room temperature, further treated with water having absorbed carbon dioxide gas and adjusted to pH 5.0, and then washed again with water. The washed film was stretched 1.01 times in the machine direction without drying, then stretched in the transverse direction by 1.05 times with a tenter, dried at 200 ° C. for a fixed length, and heat-treated at 400 ° C. for a fixed length. Next, after relaxing heat treatment at 350 ° C., it is wound up, thickness 38 μm, strength 39-38 Kg.
/ Mm ² , elastic modulus 1020-990 kg / mm ² , elongation 3
A film having a rate of 5-36% and a heat shrinkage rate of 0.04-0.04% was obtained.

[0033]

According to the film carrier for a semiconductor integrated circuit of the present invention, the flatness can be maintained even if a thin insulating substrate film is used. Therefore, the cost of the insulating substrate can be reduced by using a film thinner than before. In addition to the reduction, the flexibility of the film carrier is increased, and various applications and advantages in IC mounting can be expected.

[Brief description of drawings]

FIG. 1 is a schematic view of a plane of a conventional film carrier.

FIG. 2 is a sectional view of a portion A in FIG.

FIG. 3 is a diagram showing a schematic plan view of an example of the film carrier of the present invention.

FIG. 4 is a sectional view of a B part in FIG.

FIG. 5 shows a schematic plan view of another example of the film carrier of the present invention.

[Explanation of symbols]

 1 Insulating substrate film 2 Wiring 3 Inner lead 4 Outer lead 5 Sprocket hole 6 Device hole 7 Outer lead hole 8 Adhesive layer 9, 9'Reinforcing pattern

Claims (2)

[Claims] 1. A film having a thickness of 40 μm or less is used as an insulating substrate, and wiring patterns made of a metal layer adhered to one surface of the film are provided, and the wiring patterns are formed between the wiring patterns and / or the device holes are long. On the film divided in the width direction, at least 8 of that width in the width direction of the film.
A film carrier for a semiconductor integrated circuit, wherein a reinforcing pattern covering 0% or more is provided. 2. The strength is 25 kg / mm ² or more, the elastic modulus is 600 kg / mm ² or more, and the heat shrinkage rate at 200 ° C. is 0.
A film having a humidity expansion coefficient of 1% or less and a humidity expansion coefficient of 30 × 10 ⁻⁶ or less and a thickness of 40 μm or less is used as an insulating substrate, and a wiring pattern including a metal layer adhered to one side of the film is provided. And a reinforcing pattern extending at least 80% of the width in the width direction of the film is provided on the film obtained by dividing each wiring pattern or / and the device hall in the length direction. Film carrier for semiconductor integrated circuit.