JP4695421B2 - Manufacturing method of laminate - Google Patents

Description

  The present invention relates to a method for producing a laminate of a resin film and a metal, and more specifically, a film made of a liquid crystal polymer capable of forming an optically anisotropic molten phase (hereinafter referred to as a liquid crystal polymer film). .) And a metal foil are superposed and passed through a pressure roll and laminated to form a laminate.

In general, a liquid crystal polymer film is known as a material excellent in high heat resistance, hygroscopic dimensional stability, high frequency characteristics, and the like. Focusing on such characteristics of the liquid crystal polymer film, it has been studied to use it for an insulating material of an electronic circuit board. When used for an electronic circuit board, a laminate of a liquid crystal polymer film and a metal foil typified by a copper foil is suitable as a laminate for a wiring board.
Conventionally, a hot press apparatus has been used as a technique for producing a laminate composed of a liquid crystal polymer film and a metal foil. There is a method in which a liquid crystal polymer film cut to a predetermined size and a metal foil are placed between the upper and lower hot plates of a hot press apparatus, and then heat-pressed in a vacuum state. However, since this method is a batch method, there is a problem that it is not possible to produce a laminated body having a uniform quality in terms of peel strength, etc., and the production speed per laminated body becomes slow, resulting in a cost reduction. It has the disadvantage of becoming expensive.

  Therefore, in order to increase the production speed at a low cost, a method for continuously producing a laminate has been proposed (see, for example, Patent Document 1). By overlapping the liquid crystal polymer film and the metal foil and passing between the pressure rolls, the film and the metal foil are within a range from a temperature 80 ° C. lower than the melting point of the liquid crystal polymer to a temperature 5 ° C. lower than the melting point. The pressure roll is allowed to pass through in a state where it is pressure-bonded at the temperature. And passing the film between a heating and pressing roll containing at least one roll having a surface temperature in a range from a temperature lower than the melting point of the liquid crystal polymer by 80 ° C. to a temperature lower than the melting point by 5 ° C. It is assumed that the metal foil is pressure-bonded. In addition, the metal foil and / or film may be preliminarily heated before press-bonding. However, since the metal foil generally has a property of stretching by heating, in order to obtain a laminate having a good shape, it is stretched by heat treatment. It is preferable to control the rate. Thereby, the film of the liquid crystal polymer and the metal foil are firmly bonded to each other, and a laminate having high mechanical strength, uniform, good heat resistance and good shape can be obtained with high productivity.

Moreover, as a method for improving the above, there has been proposed a method in which a metal foil is bonded after heat-treating a liquid crystal polymer film on a heat treatment roll having irregularities on the surface (see, for example, Patent Document 2). In joining a metal sheet to a film, the residual distortion of a thermoplastic liquid crystal polymer film can be effectively eliminated by heat treatment using a heat treatment roll having irregularities on the surface. Thereby, it is said that a laminate having good characteristics and appearance can be obtained.
JP-A-5-42603 JP 2002-331589 A

  There are points to be further improved in the conventional method. For example, the temperature of the surface of the heated and pressurized roll is easily affected by fluctuations in the outside air temperature. In particular, the film or metal foil layer in contact with the roll has a thickness and is heated. If the conductivity is poor, the effect is large, and there is a problem in the stable production of the laminate. In the laminated structure of three or more, the center layer is not sufficiently heated from the pressure roll, which causes distortion. When heat-treating a liquid crystal polymer film on a heat treatment roll, there are problems that the surface of the liquid crystal polymer film is scratched and that foreign matter adheres.

  An object of the present invention is a method for producing a laminate having a good appearance and stably producing a laminate having a sufficient adhesion between a liquid crystal polymer film and a metal foil, particularly a laminate suitably used for a printed wiring board. Is to provide.

The inventors of the present invention have a process in which a film made of a liquid crystal polymer that forms an optically anisotropic molten phase and a metal foil are overlapped and passed between the pressure rolls, and the pressure roll and the film and / or The present inventors have found that by heating a metal foil without contacting it, the liquid crystal polymer film and the metal foil are sufficiently bonded to each other, and a laminate having a good appearance can be stably obtained.
That is, the manufacturing method of the laminated body of this invention is characterized by the following structures or structures.

  (1) A method for producing a laminate in which a film made of a liquid crystal polymer that forms an optically anisotropic molten phase and a metal foil are overlaid and passed between pressure rolls to laminate the film and the metal foil. In the step of passing the film and the metal foil between the pressure rolls, a heating means is provided outside the pressure roll to heat or keep the film and the metal foil and / or the pressure roll. The manufacturing method of the laminated body characterized by the above-mentioned.

(2) The method for manufacturing a laminate according to (1), wherein the heating means is a heating booth covering the entire pressure roll.
(3) The method for producing a laminate according to the above (2), wherein the heating booth temperature is in a range from a temperature 10 ° C. higher than the surface temperature of the pressure roll to a temperature lower by 150 ° C.

(4) The method for producing a laminate according to the above (1) or (2), wherein the heating means is a furnace installed at the front stage of the nip of the pressure roll.
(5) The inside of the furnace is maintained in a temperature range of 5 ° C. to 150 ° C. lower than the melting point of the liquid crystal polymer, and the heating time in the furnace of the film and metal foil is in the range of 1 second to 60 seconds. The manufacturing method of the laminated body as described in said (4).

  According to the production method of the present invention, a film and a metal foil and a non-contact type heating means are provided outside the heating and pressing roll, and the film, the metal foil, and further the heating and pressing roll are heated or kept warm, A laminate having a sufficient adhesion between the liquid crystal polymer film and the metal foil and having an excellent appearance can be produced with high productivity. The produced laminate does not impair the high heat resistance, hygroscopic dimensional stability, high-frequency characteristics, etc. possessed by the liquid crystal polymer, and is excellent in adhesion to metal foil, and is represented by, for example, a flexible wiring board. It is useful as a laminate used for a wiring board.

Hereinafter, the manufacturing method of the laminated body which concerns on this invention is explained in full detail, referring an accompanying drawing. The manufacturing method of the laminated body of the present invention is not limited by the following embodiments and examples.
FIG. 1 is a schematic explanatory view showing a method for producing a laminate according to the present invention.

As shown in FIG. 1, the method for producing a laminate of the present invention comprises a pressure roll 1 in which a film 4 made of a liquid crystal polymer that forms an optically anisotropic molten phase and metal foils 5 and 5 ′ are overlapped. The film 4 and the metal foils 5 and 5 ′ are laminated by passing between 1 ′ and 1 ′.
Here, in the step of passing the film 4 and the metal foils 5 and 5 ′ between the pressure rolls 1 and 1 ′, heating means 2 and 3 are provided outside the pressure rolls 1 and 1 ′, and the film 1 The metal foils 5, 5 ′ and the pressure rolls 1, 1 ′ are heated or kept warm.

  The film 4 is made of a liquid crystal polymer that forms an optically anisotropic melt phase. A liquid crystal polymer that forms an optically anisotropic melt phase is also called a thermotropic liquid crystal polymer. As is well known to those skilled in the art, a polymer that forms a melt phase that forms optical anisotropy is polarized when observing a sample in a molten state under a direct microscope with a polarizing microscope equipped with a heating device. Is a polymer that permeates.

The raw material of the liquid crystal polymer of the film 4 is not particularly limited, but known thermotropic liquid crystal polyesters and polyesteramides derived from the compounds (1) to (4) and derivatives thereof exemplified below. Can be mentioned. However, in order to form a polymer liquid crystal, there is an appropriate range for each combination of raw material compounds.
(1) Aromatic or aliphatic dihydroxy compounds (2) Aromatic or aliphatic dicarboxylic acids (3) Aromatic hydroxycarboxylic acids (4) Aromatic diamines, aromatic hydroxyamines or aromatic aminocarboxylic acids

  Typical examples of the liquid crystal polymer obtained from these raw material compounds include a copolymer having a structural unit represented by the following formula.

  The liquid crystal polymer film preferably has a melting point temperature of 200 to 400 ° C., particularly 250 to 350 ° C. in the following measurement methods in terms of heat resistance and workability. Here, melting | fusing point of said liquid crystal polymer film means the melting peak temperature in a differential scanning calorimetry method (DSC) when the film used for thermocompression bonding is heated at the temperature increase rate of 10 degree-C / min. The film may be blended with a lubricant, an antioxidant, a filler and the like as long as the characteristics of the film are not impaired.

  The liquid crystal polymer film is obtained by extrusion molding. Although any extrusion molding method can be applied, the known T-die method, laminate stretching method, inflation method and the like are industrially advantageous. In particular, in the inflation method and the laminate stretching method, stress is applied not only in the mechanical axis direction of the film (MD direction) but also in the direction orthogonal to the film direction (TD direction). A balanced film is obtained.

  A preferable thickness range of the liquid crystal polymer film is 500 μm or less, more preferably 10 to 500 μm, and particularly preferably 50 to 250 μm. When the film thickness exceeds 500 μm, the film becomes rigid and difficult to handle, such as being difficult to wind in a roll. On the other hand, if the film thickness is less than 10 μm, the film is easily torn and difficult to handle.

  The material of the metal foil 5, 5 'is not particularly limited in the present invention. Examples include gold, silver, copper, stainless steel, nickel, and aluminum. Examples of metal foils that are preferably used include copper foils and stainless steel foils. As the copper foil, any copper foil manufactured by a rolling method or an electrolysis method can be used. The metal foil is subjected to physical surface treatment such as roughening treatment or chemical surface treatment such as acid cleaning for the purpose of ensuring the adhesive strength with the liquid crystal polymer film, as long as the effect of the present invention is not impaired. May be.

  A preferable thickness range of the metal foil is 5 to 150 μm, more preferably 6 to 70 μm, and particularly preferably 9 to 18 μm. Although it is preferable to reduce the thickness of the metal foil from the point that a fine pattern can be formed, if the thickness is too thin, the metal foil may be wrinkled in the manufacturing process, and a circuit may be formed as a wiring board. In such a case, the wiring may be broken or the reliability of the circuit board may be lowered. On the other hand, when the thickness of the metal foil is increased, the side surface of the circuit is tapered when the metal foil is etched, which is disadvantageous for fine pattern formation.

The thermocompression bonding between the liquid crystal polymer film 4 and the metal foils 5 and 5 ′ is performed between the pressure rolls 1 and 1 ′, and usually a pair of pressure rolls is used. Examples of the pair of pressure rolls 1 and 1 ′ include a rubber roll, a metal roll, and a resin-coated metal roll. In particular, at least one of them is desirably a resin-coated metal roll having a resin coating layer having a thickness of 0.02 to 5 mm on the surface of the metal roll. The other one is suitably a rubber roll, a metal roll, or a resin-coated metal roll, but it is desirable to use a resin-coated metal roll having a resin coating layer in the same thickness range as described above. In order to improve the adhesion between the liquid crystal polymer film and the metal foil, and also to keep the pressure roll surface temperature constant, the above resin-coated metal roll is used, and the thickness of the coating layer is within the above range. Is desirable.
Although the pressure at the time of press-bonding by the pressure rolls 1 and 1 ′ is not particularly limited as long as it can be uniformly pressed in the width direction, it is preferably 5 to 200 kN / m, and preferably 10 to 40 kN / m. It is more preferable.

In the case of at least one of the pressure rolls, particularly the resin coating layer metal roll, it is preferable to heat the metal roll portion inside the pressure roll with an internal heating means. For example, it is preferable to use a heating / pressurizing roll having a metal roll portion provided with a heating mechanism of a dielectric heating system or a heat medium circulation system. Such heating is preferable from the viewpoint of making the surface temperature of the pressure roll uniform.
The material of the resin coating layer includes rubber, and specifically, a material having high heat resistance and elasticity such as fluorine rubber, silicon rubber, and polyimide is preferable. In the present invention, since thermocompression bonding to the liquid crystal polymer film is usually performed at a temperature 20 to 60 ° C. lower than the melting point of the liquid crystal polymer, the heat resistance temperature of the resin coating layer is also required to be heat resistance in this temperature range. The resin coating layer may be composed of only a single layer or a plurality of resin layers. Therefore, the surface set temperature of the heating / pressurizing roll is usually preferably in the range of 180 ° C. to 350 ° C., particularly in the range of 210 ° C. to 300 ° C., based on the melting point of the liquid crystal polymer described above.

In FIG. 1, the heating means 2 is a heating booth that covers the entire pressure rolls 1, 1 ′. The heating booth temperature is preferably in the range from a temperature 10 ° C. higher than the surface temperature of the pressure roll to a temperature lower by 150 ° C.
The surface of the heating / pressurizing roll needs to be heated or kept warm from the outside of the roll. As a method for heating or keeping warm, a method of arranging a pressure roll in the booth or a method of installing a furnace immediately before the pressure roll is preferable. As will be described later, it is more preferable to use both a method of arranging a pressure roll in the booth and a method of installing the furnace 3 immediately before the pressure roll.
The structure of the heating booth 2 is not particularly limited, but is preferably a sealed structure that surrounds the entire pressure roll, and is further covered with a heat insulating material. More preferably, the inside of the booth is heated and the temperature in the specified range is kept constant. The heating method in the booth is not particularly limited, but a hot air circulation blower, a ceramic heater, or the like is preferable. Fans may be installed in the booth. A structure in which a part of the booth can be opened is preferable for the paper passing work and cleaning of the metal foil.

  The heating means 3 shown in FIG. 1 is a furnace installed in the front stage of the nip part of a pressure roll. The inside of the furnace is preferably maintained in a range from a temperature 5 ° C. lower than the melting point of the liquid crystal polymer to a temperature 150 ° C. lower than the melting point, particularly in a range from a temperature 40 ° C. lower than the melting point to a temperature 100 ° C. lower than the melting point. . If the temperature is higher than 150 ° C. lower than the melting point, wrinkles may occur. When the temperature is 5 ° C. lower than the melting point, the film may be cut in the furnace.

The heating time in the furnace of the film and metal foil in the furnace is preferably in the range of 1 second to 60 seconds, particularly in the range of 10 seconds to 30 seconds. When the heating is less than the above range, the film and metal foil from the previous stage are not sufficiently heated and are affected by the previous stage environment. On the other hand, when the above range is exceeded, overheating is caused, which adversely affects the film and the like.
The heating method of the furnace is not particularly limited, but it is preferable that the roll surface in the vicinity of the nip portion between the liquid crystal polymer film and the metal foil and the pressure roll can be heated simultaneously. By heating the pressure roll, the roll, film, and metal foil are kept at a constant environmental temperature during nip.

  The laminate obtained by such a production method has a good form, the film layer has excellent mechanical strength, electrical properties and heat resistance of the liquid crystal polymer, and the film layer is a metal. Since it is firmly bonded to the foil not only at room temperature but also at high temperature, it is useful as a material for producing FPC, TAB tape and the like.

In the best embodiment described above, the laminate has a two-layer structure of a liquid crystal polymer film and a metal foil. However, the laminate produced in the present invention may be any layer as long as it includes at least one liquid crystal polymer film and at least one metal foil. For example, the two-layer structure shown in the following I), II) Examples of the three-layer structure shown in IV), the four-layer structure of V), and the five-layer structure of VI) can be exemplified. In the following I) to VI), in the case of a laminate having two or more films, at least one film in contact with the metal foil is a liquid crystal polymer film.
I) Film / metal foil II) Metal foil / film / metal foil III) Film / film / metal foil IV) Film / metal foil / film V) Metal foil / film / film / metal foil VI) Metal foil / film / metal Foil / film / metal foil

  In the embodiment, the liquid crystal polymer film and the metal foil are overlapped and passed between the pressure rolls at the same time or after the overlap. According to the present invention, it is possible to simultaneously bond a film and a metal foil at two or more surfaces. For example, the film and the metal foil are pressure-bonded in a state where one metal foil is superposed on both surfaces of the film. Thus, it is possible to manufacture a laminate having a three-layer structure of metal foil / film / metal foil.

  The form of the liquid crystal polymer film and the metal foil used here is preferably in the form of a roll wound from the viewpoint of productivity. A film and a metal foil wound up in a roll shape are prepared, and the film and the metal foil are continuously conveyed by a roll-to-roll.

EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited at all by these Examples.
In addition, evaluation of the laminated body obtained in the Example and the comparative example is based on the following method.

Evaluation method (1) Appearance: A laminate obtained by pressure-bonding a liquid crystal polymer film and a metal foil and a film obtained by etching the metal foil were observed visually and with an optical microscope to examine the presence or absence of deformation.
(2) Delamination strength: The delamination strength at room temperature was measured by peeling a metal foil having a width of 1 mm from the metal foil removal surface at 180 °.

Examples 1-3
An electrolytic copper foil having a thickness of 18 μm was superposed on both sides of a 25 μm-thick liquid crystal polymer film (trade name Bexter, melting point 280 ° C.) and simultaneously supplied at a rate of 2 m / min between a pair of pressure rolls. The roll surface was heated to 230 ° C. by a heating mechanism inside the roll. The heating / pressurizing roll was placed in the booth, and the booth was heated to the set temperature by a hot air circulation blower. The liquid crystal polymer film and the electrolytic copper foil were continuously manufactured by a roll-to-roll method in which a roll-like material was used as a raw material and pressure was applied by thermocompression bonding in an intermediate process. The evaluation results of the obtained laminate are shown in Table 1.

Examples 4-6
An electrolytic copper foil having a thickness of 18 μm was superposed on both sides of a 50 μm-thick liquid crystal polymer film (trade name Bexter, melting point 280 ° C.) and simultaneously supplied at a rate of 1 m / min between a pair of pressure rolls. The roll surface was heated to a set temperature by a heating mechanism inside the roll. The furnace before a heating / pressurizing roll was set to each temperature, and the pressurizing roll, the film, and the copper foil were heated by this furnace. Otherwise, the same procedure as in Example 1 was performed. Table 2 shows the evaluation results of the obtained laminate.

Examples 7-9
An electrolytic copper foil having a thickness of 18 μm was superposed on both sides of a 50 μm-thick liquid crystal polymer film (trade name Bexter, melting point 280 ° C.) and simultaneously supplied at a rate of 1 m / min between a pair of pressure rolls. The roll surface was heated to 230 ° C. by a heating mechanism inside the roll. The heating / pressurizing roll was placed in the booth, and the booth was heated to the set temperature by a hot air circulation blower. The furnace before the pressure roll was set to each set temperature, and the pressure roll, film, and copper foil were heated by this furnace. Otherwise, the same procedure as in Example 1 was performed. Table 3 shows the evaluation results of the obtained laminate.

Comparative Examples 1-3
An electrolytic copper foil having a thickness of 18 μm was superposed on both sides of a 50 μm-thick liquid crystal polymer film (trade name Bexter, melting point 280 ° C.) and simultaneously supplied at a rate of 1 m / min between a pair of pressure rolls. The roll surface was heated to each set temperature by a heating mechanism inside the roll. Heating / pressurizing roll, film and copper foil were not heated. Otherwise, the same procedure as in Example 1 was performed. Table 4 shows the evaluation results of the obtained laminate.

  The method for producing a laminate of the present invention has high industrial applicability in which a liquid crystal polymer film and a metal foil can stably produce a laminate having an excellent appearance with sufficient adhesive strength with high productivity. Is.

FIG. 1 is a schematic explanatory view showing a method for producing a laminate according to the present invention.

Explanation of symbols

1, 1 '... pressure roll 2 ... heating booth (heating means)
3 .... Furnace (heating means)
4 .... Film 5 ... Metal foil 6 ... Laminate

Claims (3)

In the method for producing a laminate in which a film and a metal foil are laminated by laminating a film made of a liquid crystal polymer that forms an optically anisotropic melt phase and a metal foil and passing between the pressure rolls,
In the step of passing the film and the metal foil between pressure rolls,
A heating means for heating or keeping warm the film and the metal foil is provided,
The heating means includes a heating booth and a furnace. The heating booth covers the entire pressure roll and the entire furnace, and heats or keeps the film, the metal foil, and the pressure roll, and a nip portion of the pressure roll. A method for producing a laminate , wherein the film and the metal foil are heated or kept warm in the furnace disposed in the previous stage . Wherein the temperature of the heating booth, a manufacturing method of a laminate according to claim 1, wherein in the range of from 10 ° C. higher temperature than the surface temperature of the pressure roll to the 0.99 ° C. lower temperature. The inside of the furnace is maintained in a temperature range of 5 ° C. to 150 ° C. lower than the melting point of the liquid crystal polymer, and the heating time in the furnace of the film and the metal foil is in the range of 1 second to 60 seconds. Item 3. A method for producing a laminate according to Item 1 or 2 .

Images