JPH0697235A - Film carrier for semiconductor integrated circuit - Google Patents

Abstract

PURPOSE:To provide the title film carrier for packaging semiconductor capable of lessening the pitch by minimizing the positional slip due to the thermal expansion during the outer lead bonding step onto a glass for LCD etc. CONSTITUTION:The title film carrier for semiconductor integrated circuit is composed of an insulating substrate comprising a thermal resistant film in linear expansion coefficient not exceeding 8X10<-6>mm/mm/ deg.C and a wiring pattern comprising metallic layer in linear expansion coefficient not exceeding 8X10<-6>mm/mm/ deg.C formed either on one or both surfaces of the insulating substrate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film carrier for semiconductor integrated circuits, and more particularly to a film carrier for semiconductor integrated circuits excellent in mechanical properties, heat resistance and dimensional stability.

[0002]

2. Description of the Related Art Semiconductor integrated circuits (hereinafter referred to as ICs)
The film carrier method, which is one of the mounting methods, is disclosed in Japanese Examined Patent Publication No. 47-3206, published by Nikkan Kogyo Shimbun, "Electronic Technology" Vol. 1974
August 12, issue 121-136, Nikkei McGraw-Hill issue "Nikkei Electronics" June 6, 1971 issue
The basic technology is shown on pages 60 to 67, and these are called, for example, the Mini-Mod method (trademark of US General Electric Company), the chip carrier method, the tape automated bonding (TAB) method, and the like. With these methods, it is possible to improve productivity and reduce manufacturing costs.

As a conventional film carrier, a polyimide film, a polyester film, a glass epoxy material or the like is used as a base material, a copper foil is adhered to these long sheets, and pattern etching is generally used. . The film carrier is a liquid crystal display (L
It is widely used for multi-pin thin-type applications such as a CD) driver IC mounting, a multi-pin LSI chip gate array TAB package, and a thermal head. LC
In D applications, the connection between the film carrier and the LCD panel (so-called outer lead bonding) is performed by thermocompression bonding through an anisotropic conductive film, but the conventional film carrier made of polyimide and copper foil has a linear expansion coefficient of LC.
Since it is considerably larger than the glass for D, the dimensional change of the pattern of the film carrier during thermocompression bonding is large, and there is a drawback that defects due to the pattern shift are likely to occur.

Japanese Unexamined Patent Publication No. 1-278737 proposes a film carrier having a dimensional stability at high temperature which uses a para-oriented aromatic polyamide film having a small linear expansion coefficient as an insulating substrate. However, when a copper foil is used as the metal layer, there is a problem that strain is likely to occur during heating due to the difference in linear expansion coefficient between the insulating substrate and the metal layer.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a film carrier for semiconductor mounting, which has a small positional displacement due to thermal expansion during outer lead bonding with an LCD panel or the like, and which can have a fine pitch. .

[0006]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to achieve the above object, and as a result, by using a base film and a conductive metal layer having a linear expansion coefficient of a specific value or less, an LCD panel. It was found that the dimensional accuracy in bonding with an LSI chip or the like can be improved, and as a result of further studying this point, the present invention has been achieved.

That is, the present invention has a linear expansion coefficient of 8 × 10 ⁻⁶ mm /
A heat-resistant film with a temperature of mm / ° C or less is used as an insulating substrate, and the linear expansion coefficient is 8 × 10 ⁻⁶ mm / on one side or both sides of the film.
A film carrier for a semiconductor integrated circuit, in which a wiring pattern made of a metal layer of mm / ° C. or less is formed. In the present invention, the insulating substrate has a linear expansion coefficient of 8 × 10 ^−6.
It is necessary to use a heat resistant film having a thickness of mm / mm / ° C or less. As such a heat resistant film, for example, a film made of a heat resistant polymer such as aromatic polyamide, aromatic polyimide or aromatic polyester is used. The linear expansion coefficient of these films varies depending on the copolymer composition and the production method, but among them, the linear expansion coefficient is 8 ×.
LCD that can use less than 10 ^-6 mm / mm / ° C
It is important to improve the dimensional accuracy when bonding to a panel.

As the heat-resistant film, para-oriented aromatic polyamide having excellent mechanical properties and dimensional accuracy is preferably used. The para-oriented aromatic polyamide is substantially composed of units selected from the group consisting of the following constitutional units. —NH—Ar ₁ —NH— (1) —CO—Ar ₂ —CO— (2) —NH—Ar ₃ —CO— (3) where Ar ₁ , Ar ₂ and Ar ₃ are each at least one. A divalent group containing an aromatic ring, (1) and (2)
Are substantially equimolar when present in the polymer,
Ar ₁ , Ar ₂ and Ar ₃ are each preferably a para-oriented group.

Here, the para orientation type means that the binding direction of the main chain in the aromatic ring is located in the para position, or in the residue composed of two or more aromatic rings, the binding directions of the main chains at both ends are coaxial. Or it means parallel. As a typical example of such a divalent aromatic group, chemical formula 1 and the like can be mentioned.

[0010]

[Chemical 1]

Here, X is --O--, --CH _2- , --S
_{O 2 -, - S -,} - CO- selected from among. Further, a part of hydrogen atoms of these aromatic rings may be substituted with a halogen group, a nitro group, a sulfone group, an alkyl group, an alkoxy group or the like. Ar ₁ , Ar ₂ and Ar ₃ may all be two or more kinds, and may be the same or different from each other.

The para-oriented aromatic polyamide is obtained, for example, by casting an optically anisotropic dope using sulfuric acid or the like as a solvent on a supporting surface and adding the dope to absorb the moisture by an isotropic method. A film can be produced by a method in which after coagulation and washing, if necessary, uniaxial or biaxial stretching is performed, and then drying is performed while controlling shrinkage. The thickness of the heat resistant film used in the present invention is preferably 30 to 125 μm, more preferably 35 to 60 μm. If the thickness is too thin, the rigidity becomes small, and the positional accuracy of sprocket holes and device holes deteriorates in the IC mounting process described later, resulting in many defective products.

In the film carrier of the present invention, the above heat-resistant film is used as an insulating substrate, and a wiring pattern made of a metal layer having a linear expansion coefficient of 8 × 10 ⁻⁶ mm / mm / ° C. or less is laminated on one side or both sides of the film. Was usually done,
It is manufactured by stacking a metal layer on a heat-resistant film and then etching it into a wiring pattern. Here, as the metal having a linear expansion coefficient of 8 × 10 ⁻⁶ mm / mm / ° C. or less, an alloy containing iron-nickel as a main component or a metal having a low linear expansion coefficient such as tantalum or molybdenum can be used. Particularly, an iron-nickel alloy containing 30 to 50% by weight of nickel is preferably used.

The heat-resistant film and the metal are usually laminated with an adhesive such as an epoxy resin. However, a metal layer directly formed on the heat-resistant film by vapor deposition, sputtering, plating or the like is used. You can also The film carrier of the present invention may have a structure having a device hole at a connection portion with an IC as shown in Japanese Patent Publication No. 47-3206, but it may also have a structure without a device hole. It is possible to mount an IC on the film. One of the features of the film carrier of the present invention is that the inner lead portion is not distorted by heating during bonding because both the base film and the metal layer have a low coefficient of thermal expansion even without device holes.

With the structure without the device hole, the inner leads are less likely to be deformed in the film carrier manufacturing process and the mounting process, and a fine pattern can be formed. The film carrier of the present invention may be a single-sided type in which a metal layer is formed on one side of an insulating substrate, or a double-sided type in which metal layers are formed on both sides.

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 the double-sided type, the front side is
The wiring pattern on the back side can be bonded to the circuits on both the front and back sides through the through holes. The film carrier on which the IC is mounted is outer lead bonded to a glass for LCD, a glass epoxy substrate ceramic substrate using a solder, an anisotropic conductive sheet, a photocurable insulating resin or the like. The film carrier of the present invention is particularly suitable for LC
Since the coefficient of linear expansion is close to that of the glass for D or the ceramic substrate, a dimensional difference from the substrate due to heating during outer lead bonding hardly occurs, and highly accurate bonding is possible.

In the film carrier of the present invention, after applying a heat resistant film and an adhesive, the sprocket holes and, if necessary, device holes are punched, a metal layer is laminated, and patterning is performed by etching. It can be manufactured by a process.

[0018]

EXAMPLES Examples will be shown below, but these Examples illustrate the present invention and do not limit the present invention. The coefficient of linear expansion of the film and the metal layer was measured between 30 ° C and 150 ° C using a thermomechanical measuring device (TMA). The thickness of the film was measured with a dial gauge having a measuring surface with a diameter of 2 mm. The strength and modulus are measured by measuring a sample having a size of 100 mm × 10 mm using a constant-speed stretch strength / strength tester at a measurement length of 30 mm and a pulling speed of 30 mm / min.

[0019]

Example 1 An example using a PPTA film as an insulating substrate is shown. Ηinh = 6. In concentrated sulfuric acid having a concentration of 99.5%.
1 of PPTA was melted at 60 ° C. to prepare a stock solution having a polymer concentration of 12%. The stock solution was degassed under vacuum while maintaining it at 60 ° C. A tank is passed through a filter, a liquid is sent by a gear pump, a dope is cast on a tantalum belt from a T-die having a slit of 0.4 mm x 300 mm, and air with a relative humidity of about 5% and a temperature of about 105 ° C is used. To make the casting dope optically isotropic,
It was introduced into water at ℃ and solidified. Then peel off the coagulated film from the belt, and in warm water at about 30 ° C, then 0.5%
It was washed by running in an aqueous solution of NaOH and further in water at room temperature. 1.15 without washing the washed film
Double lengthwise roll stretching, then transversely 1.20 times tenter stretching and further constant length drying at 260 ° C, 400 ° C
After heat treatment in, it is wound and the coefficient of linear expansion is 3.5 × 10 ^-6 mm /
mm / ° C), thickness 50 micron, strength 39 kg / mm ² ,
A film having a modulus of 1250 Kg / mm ² and ^an elongation of 28% was obtained. After applying an epoxy adhesive to this film, slit it to a width of 35 mm, and then use JISK7552-19
A sprocket hole and a device hole corresponding to the size of a raw film for motion pictures (positive grain film) defined in No. 65 are punched, and an iron-nickel alloy foil with a thickness of 20 μm (42 alloy foil, nickel content: 42%, A linear expansion coefficient of 4.7 × 10 ⁻⁶ mm / mm / ° C.) was laminated, cured and adhered.

Next, using a thermosetting silk screen printing ink as an etching resist, etching was performed with a cupric chloride / hydrochloric acid aqueous solution and tin plating was performed to form a wiring pattern. The outer lead is 100 μm wide circuit.
This was formed at a pitch of 200 μm. This outer lead part is attached to the glass for LCD using an anisotropic conductive film.
After pressure bonding at 0 ° C and cooling, the positional deviation with the mark previously attached to the glass for LCD was measured and found to be 0.0
It was 8%.

[0021]

[Comparative Example 1] A polyimide film (coefficient of linear expansion 19 × 10 ^-6 mm / mm / ° C) as an insulating substrate, and an electrolytic copper foil (coefficient of linear expansion 16.5 × 10 ^-6 mm / mm / ° C) as a metal layer. A film carrier was prepared in the same manner as in Example 1 and the positional deviation from the LCD glass was measured in the same manner.
It was 33%.

[0022]

The film carrier for a semiconductor integrated circuit of the present invention is particularly excellent in dimensional accuracy and heat resistance, has a dimensional change due to heating to the same extent as glass, ceramics, etc., and has a small distortion due to heating, and thus is particularly suitable for LCD. It is possible to extremely reduce the positional deviation during bonding with the working glass, and it is possible to achieve a fine pitch for the outer leads.

Claims (1)

[Claims] 1. A heat-resistant film having a linear expansion coefficient of 8 × 10 ⁻⁶ mm / mm / ° C. or less is used as an insulating substrate, and the linear expansion coefficient is 8 × 10 ⁻⁶ mm / mm / ° C. on one side or both sides of the film. A film carrier for a semiconductor integrated circuit having a wiring pattern formed of the following metal layers.