JPH03227623A - Manufacture of improved curl-proof coppered plate - Google Patents

Abstract

PURPOSE:To enable manufacture of a coppered plate which does not become curled significantly by binding film and copper foil together through an adhesive using a heating roll, then allowing the moisture of the whole product to be absorbed and thermally treated. CONSTITUTION:A paraoriented aromatic polyamide film 3 and copper foil 1 are bound together continuously through an adhesive 2 using a heating roll. In this manufacturing process, the film is heated in a state that its moisture is absorbed after the binding together of the film and the foil. The preferable moisture absorption state is such that the moisture content of the film should be 0.5% or higher. Thus the curling properties of the coppered plate 6 can be sharply decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to improving the curling properties of a copper-clad board using a para-oriented aromatic polyamide film. More specifically, the film exhibits excellent mechanical properties in both the longitudinal direction (hereinafter abbreviated as MD force direction) and the width direction (hereinafter abbreviated as TD force direction), and is a para-oriented aroma with excellent heat resistance and dimensional stability. This invention relates to a method for improving curl by performing a special curing method in a method for manufacturing copper-clad boards using a group polyamide film.

[Prior art] Polybara phenylene terephthalamide (hereinafter referred to as PPTA)
Arromatic aromatic polyamides, such as those represented by (1), have particularly excellent crystallinity and a high melting point, and due to their rigid molecular structure, they have heat resistance and high mechanical strength. It is a polymer material that is attracting particular attention.

It has also been reported that fibers spun from concentrated solutions exhibiting optical anisotropy exhibit high strength and modulus, and have already been put into industrial use. Also, PPTA
Some examples of molding into films have been proposed (for example, Japanese Patent Publication No. 56-4521, Japanese Patent Publication No. 57-178).
Publication No. 86, etc.).

Aromatic polyamide films are known to have excellent heat resistance, high strength, and Young's modulus. In particular, para-oriented aromatic polyamide films, in which the monomers of the constituent units mainly have linear orientation, have these properties. is particularly good,
It is expected to be applied to various uses. For example, its mechanical performance and heat resistance make it suitable for use as an insulating base material for flexible printed wiring boards (hereinafter referred to as FPC) and carrier tapes for tape automated bonding (hereinafter referred to as TAB). Proposed. (For example, JP-A-62-176835, JP-B-55-37866) Such FPC.

When used in TAB applications, it is necessary to laminate the copper foil onto the film using an adhesive.

There are two methods for manufacturing copper clad boards: a press method and a laminator method. The pressing method is similar to general hard copper-clad laminates, in which a film and a copper foil are polymerized via an adhesive, and then heated and pressed using a hot press machine to integrate them. Further, the laminator method is a method in which a film and a copper foil are continuously laminated together via an adhesive while being pressed with a heating roll and a rubber roll, and then heated and cured.

Pressing methods usually require high pressure and long heating times, so it is difficult to laminate materials with large differences in thermal expansion coefficient or thermal contraction rate, such as plastic film and copper foil. The copper clad plate has a large curl. In addition, in the case of a laminator method, heating is normally completed in a short time using a heating roll at a low pressure, so curling is small at this stage, but curling increases in the step of winding up the material into a roll and heating and curing it.

Conventionally, polyimide films and polyester films have been mainly used as base films for FPC-TABs. These films have a coefficient of thermal expansion close to copper,
When laminated, it undergoes dimensional changes similar to those of copper, so there is relatively little curling. On the other hand, para-oriented aromatic polyamide film has a smaller coefficient of thermal expansion than copper, so if copper-clad boards are manufactured using the method conventionally used for polyimide films, the cal will be considerably large, which is a disadvantage in the manufacturing method. was.

[Problems to be Solved by the Invention] An object of the present invention is to solve the drawbacks of the conventional method for manufacturing copper-clad boards, and to provide a para-oriented aromatic polyamide film and copper foil with excellent mechanical performance and heat resistance. When combining the
The purpose is to improve its curling properties.

[Means for Solving the Problems] As a result of intensive studies to solve the above problems, the present inventors have found that after continuously bonding a film and a copper foil with an adhesive using a heating roll, rolling The inventors discovered that it is possible to continuously produce copper-clad boards with minimal curl by removing the material, allowing it to absorb moisture under specific conditions, and then heat-treating it, thereby completing the present invention.

That is, the present invention provides a method for producing a copper clad board in which a para-oriented aromatic polyamide film and a copper foil are continuously laminated together using an adhesive using a heating roll and cured by heating. This is a method for producing a copper clad board with improved curling properties, which comprises heating the copper clad board in a hygroscopic state.

The para-oriented aromatic polyamide used in the present invention is substantially composed of units selected from the group consisting of the following structural units.

-NH-Ar, -NH--(I) COA r2CO--(II)-NH'
Ar3 CO---(1) where Art, Ar2 and Art are each divalent aromatic groups, and (1) and (II)
is substantially equimolar when present in the polymer.

In the polyamide film of the present invention, in order to ensure good mechanical performance, A r +, A rx'J3 and Art are each so-called para-oriented groups.

Here, the para-oriented type means that the bonds that grow the molecular chain are located coaxially or parallel to the opposite direction of the aromatic nucleus. Specific examples of such divalent aromatic groups include paraphenylene, 4.4'-biphenylene, 1.4-naphthylene, 1.5-naphthylene, 2.6-
Examples include naphthylene and 2,5-pyridazine. They may be substituted one or more with non-reactive groups such as halogen, lower alkyl, nitro, methoxy, sulfonic acid, cyan groups, etc. Ar, , Ar2 and Ar3 may be two or more types, and may be the same or different.

The polymer used in the present invention is prepared by a method known so far to obtain diamine, dicarboxylic acid, and diamine corresponding to each unit.
It can be produced from aminocarboxylic acids. Specifically, a method in which a carboxylic acid group is first induced into an acid halide, an acid imidazolide, an ester, etc. and then reacted with an amino group, or after the amino group is induced into an isocyanate group,
A method of reacting with a carboxylic acid group is used, and the polymerization methods include so-called low-temperature solution polymerization, interfacial polymerization, melt polymerization,
A solid phase polymerization method or the like can be used.

The aromatic polyamide used in the present invention may be copolymerized with groups other than those mentioned above in an amount of about 10 mol % or less, or may be blended with other polymers.

The most typical aromatic polyamide used in the present invention is poly-p-phenylene terephthalamide (hereinafter referred to as
(abbreviated as PPTA) and poly-rubenzamide.

If the degree of polymerization of the aromatic polyamide used in the present invention is too low, a film with good mechanical properties, which is the object of the present invention, cannot be obtained.
More preferably, one is selected that has a degree of polymerization that gives a logarithmic viscosity ηinh of 3.5 or more (value measured at 30°C with 0.5 g of polymer dissolved in 100 d of sulfuric acid).

Films used in the present invention generally have at least 1.3
7 g/ci or more, more preferably 1.39 g/ci
It has a density of more than This is the density necessary to ensure the mechanical properties of the film mentioned above.

The film used in the present invention preferably has a tensile modulus of 600 kg/mm 2 or more and an elongation of 10% or more in any direction within the plane of the film. A film having such isotropic mechanical properties can be obtained, for example, by wet film formation from a liquid crystal stock solution of a para-isotropic aromatic polyamide typified by PPTA. However, the film obtained by directly coagulating PPTA from a liquid crystal solution state has large anisotropy in mechanical properties and dimensional accuracy, and has poor performance in FPC, TAB, etc. In other words, a film obtained by extruding the liquid crystal in a liquid crystal state, performing an optical isostatic ratio, and solidifying the film is preferably used.

The film used in the present invention preferably has a crystal orientation angle of 60 degrees or less in the direction in which the peak diffraction intensity in the range of 2θ-15 to 25 degrees by X-rays incident parallel to the film surface is maximized. A known method can be used to measure the crystal orientation angle, for example, as follows. Predetermined 2θ
A diffraction intensity curve is obtained by placing the counter at an angle of and rotating the film 180 degrees. When X-rays are incident perpendicularly to the film surface, the film is rotated between 90 degrees around the maximum intensity. The half width of this curve is determined and used as the crystal orientation angle of the sample. If necessary, several films can be stacked for measurement.

Next, a method for manufacturing the para-oriented aromatic polyamide film used in the present invention will be specifically described.

First, in the first step, aromatic polyamide is dissolved in a solvent. As the solvent, strong acids such as concentrated sulfuric acid, chlorosulfuric acid, fluorosulfuric acid, methanesulfonic acid, and trifluoromethanesulfonic acid are used. The concentration of the polymer in the stock solution is preferably one that does not show optical anisotropy at room temperature or higher temperature and is higher than the concentration, specifically about 10% by weight or more,
It is preferably used in an amount of about 12% by weight or more and 15% by weight or less.

When preparing a stock solution, it is preferable to exclude air, and the preparation is usually carried out in an atmosphere of an inert gas such as nitrogen or argon.

The stock solution can be prepared by heating if necessary, and can also be subjected to defoaming, filtration, etc.

The stock solution prepared in this way is cast into a film using a doctor knife or extruded from a die.
Although it may be solidified as it is, especially when a liquid crystal stock solution is used, it is preferable to change the casting stock solution to optical isotropy by heating or absorbing moisture, and then solidify it. It is preferred that the stock solution avoid contact with air or oxygen during casting or optical isotropy from the liquid crystal.

As a coagulating liquid, water, dilute sulfuric acid, sodium hydroxide solution,
A sodium chloride solution or the like can be used. The temperature of the coagulation bath is not particularly limited, and is usually about -10°C.
The temperature range is 50°C.

After the coagulated film is neutralized and washed with water,
1.01 in one or two directions prior to drying if desired.
The film is stretched by about 1.4 times, and then dried under tension, at a constant length, or slightly stretched or shrunk while restricting free shrinkage of the film.

Performance can be improved by further heat-treating the film obtained by drying in this manner at a high temperature, if necessary. The heat treatment temperature is 300° C. to 450° C., the heat treatment time is about 5 seconds to 10 minutes, and it can be performed under tension, constant length, or limited shrinkage.

The obtained film may be subjected to surface treatment if necessary.

In the manufacturing method of the present invention, such a para-oriented aromatic/aromatic polyamide film is laminated to copper foil using a heated roll via an adhesive.

Various adhesives can be used in the present invention, such as epoxy compounds, acrylic compounds, phenol compounds, and thermosetting polyphenylene oxide compounds, and are not particularly limited.

The copper foil used in the present invention may be an electrolytic copper foil or a rolled copper foil, and its thickness is usually 0.015 to 0.105 mm, and may be surface-treated if necessary.

The heating roll used in the present invention may be any commonly available combination of rubber/rubber, rubber/metal, metal/metal, etc., as long as it is equipped with a pressing mechanism.

In the manufacturing method of the present invention, the lamination pressure, heating temperature, etc. are appropriately set according to the adhesive used, but usually the lamination pressure is in the range of 1 to 5 (kg/cm), and the heating temperature is 100 kg/cm. A range of 200 (t) to 200 (t) is preferably used.

In the manufacturing method of the present invention, after laminating the film and the copper foil together using a heating roll, it is necessary to allow the film to absorb moisture, and to heat the film while maintaining the moisture absorption. This hygroscopic heat treatment can be performed even when the adhesive is not cured, or can be performed after the adhesive is cured. That is, the procedure is as follows: (1) Immediately after laminating with a heating roll, moisture is absorbed and heat curing is performed. ■ Laminate with heated rolls, pre-cure at a relatively low temperature without absorbing moisture, then absorb moisture and heat cure at a high temperature. (2) Any method can be used, such as laminating with a heating roll, curing without absorbing moisture, and then absorbing moisture and heating.

Curing of the adhesive is carried out in combination with the above-mentioned treatments as appropriate, but as for the temperature conditions for curing, a multi-stage curing method in which pre-curing is performed at a relatively low temperature and then curing at a high temperature is preferably used. −
Curing in stages is not preferable because it causes significant misalignment between the film and the copper foil.

The moisture absorption state carried out in the production method of the present invention is preferably carried out under conditions such that the moisture content of the film is 0.5% or more. Specifically, the moisture absorption state is preferably carried out under conditions such that the film moisture content is 0.5% or more. Use methods such as applying high-temperature steam.

The heat curing treatment carried out in the manufacturing method of the present invention is usually carried out in the state of being wound up into a roll, but it is preferable to place the copper on the outside.

[Example] Examples of the manufacturing method of the present invention are shown below, but these Examples are for explaining the present invention and are not intended to limit the present invention. In the examples, parts by weight or weight % are shown unless otherwise specified.

Further, the logarithmic viscosity (η1nh) was measured by dissolving 0.5 g of the polymer in 100 volumes of 98% concentrated sulfuric acid at 30°C in a conventional manner. The viscosity of the dope was measured using a B-type viscometer at a rotation speed of 1 rpm. The thickness of the film is 2[lll1] in diameter.
Measurements were made using a dial gauge with a measurement surface of 1.

To measure the curl, place a test piece of MD: 200 mm XTD: 35 on a surface plate in an atmosphere of 25°C and 60% (absolute humidity 15 g/rrr) with the concave side facing downward as shown in Figure 2. The maximum floating length was measured for each shell using a ruler.

Example 1 A PPTA polymer having an ηinh of 5.5 was dissolved in 99.7% sulfuric acid at a polymer concentration of 12.0% to obtain a dope with optical anisotropy at 60°C. The viscosity of this dope was measured at room temperature and was found to be 14,500 poise.

To facilitate film formation, the tope was maintained at approximately 70°C and degassed under vacuum. This case also had optical anisotropy as described above, and the viscosity was 420 o poise.

This dope is passed through a filter from the tank and heated to approximately 70°C.
The cast dope was passed through a 1.5 m curved pipe through a gear pump and into a die while maintaining the same temperature, and cast from the die with a slit of 0.3 nrm x 300 mm onto a mirror-polished Hastelloy belt. Approximately 95%
After blowing air at 0'C and comparing the optical force, hold it on the heald for about 1 minute, and then remove it with the belt at 2 O'C.
It was introduced into a 0% by weight aqueous sulfuric acid solution and coagulated.

Next, the coagulated film is peeled off from the belt and washed by running it through a water tank at about 20'C using rotating rollers (residence time: about 3 minutes). It was sandwiched between two frames made of aluminum and dried for a fixed length in an air oven maintained at 200°C.

Next, a film with a thickness of 0.040 nm obtained by heat treatment for a fixed length in an air oven kept at 350°C and a rolled copper foil with a thickness of 0.035 mm with a surface treatment on the adhesive side were epoxied. After laminating continuously with a heating roll via a system adhesive, the copper foil side was rolled up and heated at 80°C for 24 hours, then heated at 160°C for 4 hours, After cooling, 25°C, 60% (absolute humidity 15g/
rrf) After absorbing moisture in an atmosphere for 20 hours, it was heat-treated at 150°C for 2 hours to obtain a copper-clad board.

Example 2 A 0.040 m thick film obtained in the same manner as in Example 1 and a 0.035 mm thick electrolytic copper foil whose adhesive surface had been surface-treated were continuously bonded with a heated roll via an epoxy adhesive. After lamination, heat curing was carried out under the same conditions as in Example 1.
After absorbing moisture for 0 hours, heat treatment was performed at 150° C. for 2 hours to obtain a copper-clad board.

Example 3 A film with a thickness of 0.040 mm obtained in the same manner as in Example 1 and an electrolytic copper foil with a thickness of 0.035 mm whose adhesive surface had been surface-treated were continuously bonded with a heated roll via an epoxy adhesive. After lamination, it was heated and cured under the same conditions as in Example 1,
After absorbing moisture for 20 hours, heat treatment was performed at 200°C for 2 hours to obtain a copper-clad board.

Comparative Example 1 After completing the heat curing treatment in the same manner as in Example 1, a copper clad board without moisture absorption heat treatment was obtained.

Comparative Example 2 After performing heat curing treatment in the same manner as in Example 1, heat treatment was again performed at 160° C. for 2 hours without moisture absorption to obtain a copper clad board.

Comparative Example 3 After heat curing treatment in the same manner as in Example 1, moisture was absorbed for 5 hours, and heat treatment was performed at 150°C for 2 hours to obtain a copper clad board.

Table 1 shows the curl state of the copper-clad plates obtained in the above Examples and Comparative Examples.

(Leaving space below) Table * Width direction of TD force direction film, length direction of MD force direction film [Effects of the invention] The manufacturing method of the present invention is based on the production method of the present invention, in which a loosely oriented aromatic IJ7 medium film and a copper foil are The curling property of bonded copper clad plates can be significantly reduced. In addition, a copper-clad laminate can be obtained that takes advantage of the mechanical properties and heat resistance of the para-oriented aromatic polyamide film, and is useful as a material for electronic substrates such as FPC: TAB.

[Brief explanation of drawings]

FIGS. 1 and 2 show schematic cross-sectional views of copper-clad plates. 1st
The figure shows the case of a curl of a flexible copper clad board with the copper foil side on the outside, that is, a (+) curl. Figure 2 shows the case of a curl with the copper foil side on the inside, that is, a (-) curl. FIG. 3 shows a method for measuring the curl of a copper-clad board.

Claims (1)

[Claims] 1. In a method for producing a copper-clad board in which a para-oriented aromatic polyamide film and a copper foil are continuously laminated with an adhesive using a heating roll and cured by heating, the film is brought into a moisture-absorbing state after being laminated with a heating roll. A method for manufacturing a copper clad board with improved curling properties, characterized by heating it with.