JP3344679B2 - Polyethylene naphthalate film for TAB - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyethylene naphthalate film for TAB, and more particularly, to a film having excellent dimensional stability, heat resistance, moisture absorption resistance, chemical resistance, and mechanical properties. The present invention relates to a polyethylene naphthalate film for TAB having excellent flatness, workability, and various electrical properties.

[0002]

2. Description of the Related Art Conventionally, in the mounting technology of IC chips, automation has been attempted in order to mass-produce products having excellent performance. As one of the methods developed for this automation, a method of incorporating an IC chip into a film having a long sprocket hole by wireless bonding [Tape Automated Bond]
ing (TAB)].

Conventionally, as the above TAB carrier film material (insulating film), polyimide film,
Glass epoxy tape in which glass fiber is impregnated with epoxy resin, BT resin tape in which glass fiber is impregnated with BT resin, polyethylene terephthalate film and the like are widely used. Above all, polyimide films have become the main carrier material for TAB because of their excellent heat resistance.

However, since the polyimide film has a higher coefficient of humidity expansion than other materials, the dimensional change due to moisture absorption is large. In addition, polyimide films with improved hygroscopicity have poor bendability, resulting in a high failure rate during outer lead bonding, and are liable to tear during transport and positioning guides during the TAB process, resulting in poor clutch resistance. Chip. In addition, polyimide films are extremely expensive due to manufacturing problems.

[0005] Glass epoxy tape and BT resin tape are excellent in dimensional stability due to heating and moisture absorption. However, a large amount of impregnated resin and glass fiber scraps are generated from the cross section of the tape in the punching and slitting steps, and thus a clean room is required. It is not suitable for mounting precision semiconductors due to contamination. Further, if excessive force is applied to the tape during punching or slitting, the tape is torn, and the punching die and the slit blade are liable to wear. Polyethylene terephthalate films are all excellent except for the heat resistance, but the TAB manufacturing process has a severe heat process and its use is limited. Therefore, in the case of TAB film carrier materials, it is desired to overcome the above-mentioned problems and to develop a single material that is inexpensive.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide excellent dimensional stability, heat resistance, moisture absorption resistance, chemical resistance, mechanical properties, and
An object of the present invention is to provide a polyethylene naphthalate film for TAB which is excellent in flatness, handling workability and various electrical properties of the film.

[0007]

Means for Solving the Problems In view of the above problems, the present inventors have made intensive studies on a film carrier material for TAB. As a result, by using a polyethylene naphthalate film having a specific coefficient of thermal expansion within a specific range, the TAB film can be used.
The inventors have found that the properties required for the film carrier for B are highly satisfied, and have completed the present invention.

That is, the gist of the present invention is that the coefficient of thermal expansion (αT) in the in-plane direction of the film is not less than 9 × 10 ⁻⁶ / ° C.
TAB characterized by being not more than 0 × 10 ⁻⁶ / ° C. and the absolute value of the difference between the maximum thermal expansion coefficient αTmax and the minimum thermal expansion coefficient αTmin in the in-plane direction of the film is within 6 × 10 ⁻⁶ / ° C. For polyethylene naphthalate film.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The polyethylene naphthalate referred to in the present invention refers to a polymer whose constituent units are substantially composed of ethylene-2,6-naphthalate units.
Also included are ethylene-2,6-naphthalate polymers modified with up to mol%, preferably up to 5 mol% of the third component.

In general, polyethylene naphthalate is produced by condensing naphthalene-2,6-dicarboxylic acid or a functional derivative thereof (eg, dimethyl naphthalene-2,6-dicarboxylate) with ethylene glycol in the presence of a catalyst. Is done. In this case, as the third component, for example, a dicarboxylic acid such as adipic acid, sebacic acid, phthalic acid isophthalic acid, terephthalic acid, naphthalene-2,7-dicarboxylic acid, or a lower alkyl ester thereof, or p-oxybenzoic acid Oxycarboxylic acids or lower alkyl esters thereof, or dihydric alcohols such as propylene glycol, trimethylene glycol, tetramethylene glycol, pentamethylene glycol and hexamethylene glycol can be exemplified. If the degree of polymerization of polyethylene naphthalate is too low, the mechanical properties deteriorate. Therefore, the intrinsic viscosity of the polyethylene naphthalate used in the present invention is preferably 0.40 or more, more preferably 0.45 to 0.9.

In the present invention, a film as a TAB film carrier material is obtained from the above-mentioned polyethylene naphthalate. For this purpose, the following method is employed. For example, usually melt-extruded into a sheet at 290 to 330 ° C., cooled and solidified at 40 to 80 ° C. to form an amorphous sheet, and then at 130 to 170 ° C. in the vertical and horizontal directions with an area magnification of 4 to 20 times. The film is biaxially stretched sequentially or simultaneously, and then heat-treated at 180 to 270 ° C.

When stretching in the longitudinal and transverse directions, each may be stretched in one step, or if necessary, may be stretched in multiple steps, or a heat treatment section for relaxing orientation may be provided between the multiple steps. You can also. Further, after the biaxial stretching, the film may be stretched again before being subjected to the next heat treatment step. In particular, in order to increase the strength, a method is often employed in which after biaxial stretching, re-stretching is performed at a temperature of 140 to 200 ° C. in the longitudinal and transverse directions by 1.05 to 4.0 times, and then heat treatment is performed.

In the present invention, as described above, TAB
The most important feature of the present invention is that the film has a coefficient of thermal expansion (αT) of 9 × 10 ^{−6 in} the in-plane direction of the film.
℃ and 20 × 10 ^-6 / ℃ or less, the maximum thermal expansion coefficient αTmax and the minimum thermal expansion coefficient αTmi in the in-plane direction of the film.
The point is that the absolute value of the difference between n is within 6 × 10 ⁻⁶ / ° C.

That is, according to the findings of the present inventors, T
Since the carrier film material for AB is used by being bonded to a copper foil, its thermal expansion coefficient needs to be close to that of copper. If the thermal expansion coefficient (αT) exceeds 20 × 10 ⁻⁶ / ° C., copper When bonded to the foil, the copper foil is curled due to a difference from the thermal expansion coefficient of the copper foil, and cannot be used. Although a clear cause is not known, the thermal expansion coefficient (α
Even if T) is less than 9 × 10 ⁻⁶ / ° C., curling similarly occurs, making it unusable. Further, even when the absolute value of the difference between the maximum thermal expansion coefficient αTmax and the minimum thermal expansion coefficient αTmin in the in-plane direction of the film exceeds 6 × 10 ⁻⁶ / ° C., it can be used because it is curled when it is bonded to a copper foil. Disappears.

In order to obtain the above-mentioned coefficient of thermal expansion, a biaxially oriented polyethylene naphthalate film is used for 180
When the heat treatment is performed at a temperature in the range of -270 ° C, the crystallinity of the film is adjusted to 30-60%, preferably 35-55%. The obtained polyethylene naphthalate film may be used as it is, and its surface may be subjected to a surface treatment such as a corona discharge treatment or a low-temperature plasma treatment in order to improve the adhesiveness to the copper foil.

In the present invention, the film preferably has a melting specific resistance of 5 × 10 ^{7 to} 5 × 10 ¹⁰ Ω-cm. In obtaining an amorphous sheet from a molten polymer, it is known that a method of giving an electrostatic charge to the sheet and strongly pressing it against a rotating cooling drum, that is, an electrostatic application cooling method is effective, It is also known that this effect can be sufficiently exerted by reducing the specific resistance of the molten polyethylene naphthalate.

However, when the specific resistance of the molten polyethylene naphthalate is less than 5 × 10 ⁷ Ω-cm, the electrostatic application cooling method can be effectively applied, and the flatness of the film is excellent. , The volume resistivity becomes small and the value as an electrical insulating material is impaired.
On the other hand, when the specific resistance exceeds 5 × 10 ¹⁰ Ω-cm,
Although the volume resistivity at high temperatures is significantly improved,
The cooling effect of the electrostatic application is insufficient, and the flatness of the film is hardly improved.

In order to adjust the specific resistance of polyethylene naphthalate to the above-mentioned desired value, the following method may be adopted. That is, in order to reduce the specific resistance, the metal component may be solubilized in polyethylene naphthalate. For that purpose, for example, a relatively small amount, for example, an equimolar or less of a phosphorus compound with respect to the metal element used as a transesterification reaction catalyst or the metal element added after the transesterification reaction or the esterification reaction as necessary. Is preferably employed.

On the other hand, in order to increase the specific resistance, the amount of the metal element dissolved in the polyethylene naphthalate may be reduced. Specifically, the amount of the metal compound soluble in the reaction system is reduced or, if a large amount of the metal compound is used, most of the metal salt is insoluble in polyethylene naphthalate, such as a carboxylate, What is necessary is just to precipitate as phosphate, phosphite and the like. More specifically, for example, it can be achieved by allowing a phosphorus compound in an equimolar amount or more to act on a metal element such as calcium or manganese used as a transesterification catalyst.

In the present invention, in order to obtain polyethylene naphthalate having a specific resistance in a specific range as described above,
It is preferable that the specific resistance of polyethylene naphthalate to be used for film formation is adjusted in advance. The film thus obtained is excellent in flatness because the electrostatic application cooling method can be effectively applied at the time of forming an amorphous sheet, and has excellent electrical properties at high temperatures, particularly, in terms of volume resistivity. Significantly improved. In the present invention, the film thickness is usually 20 to 3
It is selected from the range of 00 μm, preferably 30 to 250 μm, more preferably 50 to 200 μm.

In the present invention, if necessary, a fine inert compound is mixed with polyethylene naphthalate. One of the methods of compounding the inert compound is a metal compound dissolved in the reaction system during the production of polyethylene naphthalate,
For example, there is a so-called precipitation particle method in which a phosphorus compound or the like is allowed to act on a metal compound dissolved in the system after the transesterification reaction to precipitate fine particles. This method is simple and can be industrially easily adopted. As another method, there is a so-called additive particle method in which fine particles are mixed with polyester in any of the steps from the polyester production step to the extrusion step before film formation. The above-mentioned method may be adopted.

Examples of the fine particles used in the additive particle method include silicon oxide, titanium oxide, zeolite, silicon nitride, boron nitride, celite, alumina, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, barium sulfate, and calcium phosphate. , Lithium phosphate, magnesium phosphate, lithium fluoride, aluminum oxide, silicon oxide, titanium oxide, kaolin, talc, carbon black, silicon nitride, boron nitride, and a cross-linked resin having a high crosslinking height as described in JP-B-59-5216. Molecular fine powder can be mentioned.

The shape of the fine particles may be spherical, massive, or flat, and the hardness, specific gravity, color and the like are not particularly limited. The average particle size of the fine particles is not particularly limited, but is usually 0.01 to 10 μm, preferably 0.05 to 8 as an equivalent spherical diameter.
It is selected from the range of μm. The fine particles may be used alone or in combination of two or more.

The amount of the fine particles to be added is usually from 0.05 to
It is 3% by weight, preferably 0.1 to 2% by weight. If the addition amount is less than 0.05% by weight, the film has poor slipperiness and poor winding properties. If it exceeds 3% by weight,
The degree of roughening of the film surface is too large, resulting in poor bonding with the copper foil.

[0025]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist of the present invention. The methods for measuring physical properties used in the present invention are shown below.

(1) Average particle size of fine particles Centrifugal sedimentation type particle size distribution analyzer (Shimadzu Corporation “S”
A-CP3 type "), and the particle size was measured by a sedimentation method based on Stokes' resistance law. Integration of equivalent spherical distribution of particles obtained by measurement (based on volume)
The value of 50% was defined as the average particle size.

(2) Melt specific resistance [ρv] 12 g of polyethylene naphthalate was put into a test tube with branches.
After immersing in a 295 ° C. oil bath and completely melting, completely removing bubbles by repeating vacuum-nitrogen gas, inserting a stainless steel electrode into the melt, holding for 10 minutes, and then applying a DC voltage of 3 KV. Is applied. The current value immediately after the application is read, and the specific resistance is calculated according to the following equation. In the formula, ρv is a specific resistance (Ω · cm), I is a current value (A), S is a sectional area of the electrode (cm ² ), and l is a distance between the electrodes (cm).

[0028]

Ρv (Ω · cm) = (3000 ÷ I) × (S ÷ 1)

(3) Coefficient of thermal expansion Constant load elongation tester ("TTL2 type" manufactured by Nippon Automatic Control Co., Ltd.)
Is placed in a thermo-hygrostat to measure. The measurement sample is
A heat treatment is performed in advance under predetermined conditions (for example, 70 ° C., 30 minutes). Then, this sample is attached to a tester, and the temperature expansion coefficient is measured by reading a dimensional change between a temperature of 20 ° C. and a relative humidity of 60% RH and a temperature of 40 ° C. and a relative humidity of 60% RH. The original sample length at this time is 5
05 mm, sample width is 1/4 inch. The load applied during the measurement was constant at a width of 5 g / (1/4) inch.

When a long sample cannot be obtained, the measurement can be performed using a thermomechanical analyzer ("TM-3000" manufactured by Vacuum Riko Co., Ltd.). When calculating the difference between the maximum value and the minimum value of the thermal expansion coefficient, "TM-3000" is used. The dimensions of the sample were 15 mm in length and 5 mm in width. The temperature was 10 ° C., the humidity was 0% RH, the temperature was 40 ° C., and the humidity was 0.
Determined by reading the dimensional change in% RH.

(4) Difference in the in-plane direction of the thermal expansion coefficient in the film plane According to the method described in (3), the value in each direction is measured at every 15 ° or 30 ° to determine <maximum value−minimum value>.

(5) Evaluation of curl After a polyethylene naphthalate film was coated with an epoxy-based adhesive to a coating thickness of 15 μm using a reverse coater, it was slit to a width of 35 mm to obtain a film carrier tape. This film carrier tape and a copper foil having a thickness of 35 μm were bonded by a roll laminator having a surface temperature of 200 ° C. The bonding linear pressure was 4 kg / cm, and the speed was 0.6 m / min. The obtained 35-mm-wide laminated film was placed on a flat table so that the upper surface was concave, and the curling amount was the height of the curl up from the corner table. Then, when the curl amount is less than 7 mm, ：: the curl amount is 7 m.
m or more was represented by x.

Examples 1-2 and Comparative Examples 1-4 100 parts of dimethyl naphthalene-2,6-dicarboxylate,
60 parts of ethylene glycol and 0.09 part of magnesium acetate tetrahydrate were placed in a reactor, heated and heated, and methanol was distilled off to carry out a transesterification reaction. The transesterification was substantially completed by heating. Next, the particle diameter is 0.8 μm
Was added as an ethylene glycol slurry, and 0.03 part of phosphoric acid and 0.035 part of antimony trioxide were further added, and a polycondensation reaction was carried out by a conventional method to obtain a polyethylene having an intrinsic viscosity of 0.50. Naphthalate was obtained. The obtained polymer was treated at 0.3 mmHg and 240 ° C for 8 hours.
Solid phase polymerization was carried out for an hour to obtain polyethylene naphthalate having an intrinsic viscosity of 0.65. The specific resistance of the obtained polyethylene naphthalate at the time of melting was 1.2 × 10 ⁸ Ω-cm.

Next, the obtained polyethylene naphthalate was extruded at 295 ° C. from an extruder into a sheet to form an amorphous sheet by an electrostatic application cooling method. The obtained amorphous sheet was subjected to a heat treatment after stretching to prepare a biaxially oriented film having a thickness of 120 μm. The stretching and heat treatment conditions are shown in Table 1.

[0035]

[Table 1] Example Comparative Example 1 2 1 2 3 Vertical Stretch ratio 3.6 3.5 3.4 3.6 3.2 Lateral stretch ratio 3.6 3.6 3.4 3.6 3.7 Heat setting temperature (° C) 220 240 250 100 220 Thermal expansion coefficient (αT) (× 10 ⁶ / ° C) 13 10 7 25 13 | αT _max −αT _min | (× 10 ⁶ / ℃) 3 5 3 3 10 Curl effect ○ ○ × × × ────────────────────────────── ──────

[0036]

According to the present invention as described above, a TA which is inexpensive and has various characteristics highly satisfied compared with the prior art.
A film carrier material for B can be provided, and the industrial value of the present invention is high.

Continuation of the front page (56) References JP-A-5-21533 (JP, A) JP-A-5-212787 (JP, A) JP-A-6-58992 (JP, A) JP-A-6-97235 (JP) , A) JP-A-7-43904 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/60 C08J 5/18 C08J 7/02

Claims (1)

(57) [Claims] 1. A coefficient of thermal expansion (α) in the in-plane direction of a film.
T) is 9 × 10 ⁻⁶ / ° C. or more and 20 × 10 ⁻⁶ / ° C. or less,
The absolute value of the difference between the maximum thermal expansion coefficient αTmax and the minimum thermal expansion coefficient αTmin in the in-plane direction of the film is 6 × 10 ⁻⁶ /
A polyethylene naphthalate film for TAB, wherein the temperature is within ° C.