JP2001239585A - A metal-clad laminate and a method for producing the same. - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a good appearance by using a thermoplastic liquid crystal polymer film and a metal sheet, to have a sufficient adhesive force between the thermoplastic liquid crystal polymer film and a metal sheet for a circuit, and to have a dimension. Provided is a method capable of producing a metal-clad laminate having excellent stability. A method of manufacturing a metal-clad laminate by thermally bonding a film made of a thermoplastic polymer capable of forming an optically anisotropic molten phase and a metal sheet for a circuit includes: (1) a thermoplastic liquid crystal polymer film; Is heat-treated between a pair of heating rolls so that the adhesive force between the fine layers present in the thickness direction of the thermoplastic liquid crystal polymer film is at least 0.5 kg / cm or more. The sheets are heat bonded.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film made of a thermoplastic polymer capable of forming an optically anisotropic molten phase (hereinafter, this may be referred to as a thermoplastic liquid crystal polymer). (Which may be referred to as a plastic liquid crystal polymer film) and a metal-clad laminate obtained by the method. The metal-clad laminate obtained by the present invention has excellent dimensional stability, low hygroscopicity, heat resistance, chemical resistance and electrical properties derived from the thermoplastic liquid crystal polymer film used as the electrical insulating material. It is useful as a material for flexible wiring boards and circuit boards for semiconductor mounting.

[0002]

2. Description of the Related Art Conventionally, when a metal-clad laminate used for a printed wiring board or the like is manufactured by using a thermoplastic liquid crystal polymer film, a vacuum heat press device is used to form a laminate between the two hot flat plates. A thermoplastic liquid crystal polymer film cut into a predetermined size and a metal foil are placed on top of each other, and heated and pressed in a vacuum state (batch type vacuum hot press lamination method). However, since this vacuum hot press lamination method is a batch type, the time for stacking the materials, the time for one press, and the time for removing the materials after the press are increased, and the metal-clad laminate 1
The production speed per sheet is slow, and the cost is high.
Further, if the equipment is improved so that a large number of sheets can be manufactured at the same time in order to increase the production speed, the equipment becomes large and the equipment cost increases, which is not preferable. Therefore, development of a manufacturing method capable of solving this problem and providing a metal-clad laminate at low cost is required.

[0003] In order to increase the production speed at a low cost, a method for continuously producing a metal-clad laminate has been proposed. For example, (1) a method in which a thermoplastic liquid crystal polymer film and a metal foil are superposed and first brought into contact with a heated roll and then pressed by a rubber roll or a rubber-coated roll (Japanese Patent Laid-Open No. 5-42603)
(2) While running two metal plates,
After heating by bringing it into contact with a metal plate heating roll and temporarily bonding the film-shaped resin to the heated metal plate, the two metal plates are heated and joined by a non-contact heating means between the heat bonding rolls. A method of introducing, passing, heating and bonding (see Japanese Patent No. 2561958) and the like are known.
However, since the thermoplastic liquid crystal polymer film has a layered structure in the thickness direction, it has a disadvantage that it is easily peeled inside the layered structure, and the conventional method has insufficient adhesion to the metal sheet for a circuit. And could not be used as an electric wiring circuit board.

On the other hand, there has been proposed a method for improving the internal peeling of a thermoplastic liquid crystal polymer film itself. For example, the method described in JP-A-8-90570 is a method for improving the in-layer peel resistance of a film. However, it describes only the improvement of surface properties such as abrasion resistance, but does not mention any adhesive force when directly bonded to a circuit metal sheet. Furthermore, there has been no consideration at all in the industrial method of producing a metal-clad laminate by thermally joining a thermoplastic liquid crystal polymer film and a metal sheet for a circuit.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a metal having a good appearance, a sufficient adhesive strength between a thermoplastic liquid crystal polymer film and a metal sheet for a circuit, and excellent dimensional stability. It is an object of the present invention to provide a method for producing a laminate and a metal-clad laminate obtained by the method.

[0006]

Means for Solving the Problems The present inventors have made intensive studies to achieve the above object, and as a result, a thermoplastic liquid crystal polymer film and a metal sheet for a circuit are thermally joined to produce a metal-clad laminate. In the method, 1) heat-treating the thermoplastic liquid crystal polymer film between a pair of heating rolls so that the adhesive force between the fine layers existing in the thickness direction of the thermoplastic liquid crystal polymer film is at least 0.5 kg /
cm) or more, and 2) having a sufficient adhesive strength between the thermoplastic liquid crystal polymer film and the circuit metal sheet by thermally bonding a circuit metal sheet to one or both surfaces of the thermoplastic liquid crystal polymer film; The inventors have found a method for obtaining a metal-clad laminate having excellent dimensional stability, and have completed the present invention.

In the present invention, it is preferable that the thermoplastic liquid crystal polymer film and the metal sheet for a circuit are continuously subjected to thermal bonding. By performing it continuously, a metal laminate can be manufactured at low cost. Continuous thermal bonding
For example, it can be performed using a heated roll.

The raw materials of the thermoplastic liquid crystal polymer film used in the present invention are not particularly limited, but specific examples thereof include compounds classified into (1) to (4) below and compounds thereof. Known thermotropic liquid crystal polyesters and thermotropic liquid crystal polyesteramides derived from derivatives can be mentioned. However, in order to obtain a polymer capable of forming an optically anisotropic molten phase, it goes without saying that there is an appropriate range for each combination of the starting compounds.

(1) Aromatic or aliphatic dihydroxy compounds (see Table 1 for typical examples)

[0010]

[Table 1]

(2) Aromatic or aliphatic dicarboxylic acids (see Table 2 for typical examples)

[0012]

[Table 2]

(3) Aromatic hydroxycarboxylic acids (see Table 3 for typical examples)

[0014]

[Table 3]

(4) Aromatic diamine, aromatic hydroxyamine or aromatic aminocarboxylic acid (see Table 4 for typical examples)

[0016]

[Table 4]

Representative examples of thermoplastic liquid crystal polymers obtained from these starting compounds include copolymers (a) to (e) having the structural units shown in Table 5.

[0018]

[Table 5]

As the thermoplastic liquid crystal polymer, in order to obtain the desired heat resistance and processability of the film, the temperature is in the range of about 200 to about 400 ° C., especially about 250 ° C.
Those having a melting point in the range of from about 350 ° C. to about 350 ° C. are preferred, but those having a relatively low melting point are preferred from the viewpoint of film production.

The thermoplastic liquid crystal polymer film used in the present invention is obtained by extruding a thermoplastic liquid crystal polymer. Although any extrusion molding method can be applied, a well-known T-die method, a laminate stretching method, an inflation method and the like are industrially advantageous. In particular, in the inflation method or the laminate stretching method, not only the mechanical axis direction (hereinafter abbreviated as MD direction) of the film but also a direction orthogonal thereto (hereinafter T).
(Hereinafter abbreviated as D direction), a stress is also applied, so that a film having good balance of mechanical properties and thermal properties in the MD direction and the TD direction can be obtained.

Prevention of separation between the fine layers existing in the thickness direction of the thermoplastic liquid crystal polymer film is achieved by: 1) keeping the thermoplastic liquid crystal polymer film at a temperature not lower than the softening temperature of the film and not higher than the melting point of 10 ° C. or lower. A calendering process is performed between a pair of heated metal pressure rolls so that the adhesive strength between the fine layers existing in the thickness direction of the film is 0.5 kg / cm or more. 2) The maximum roughness (JIS B0601) on the surface ( R _max ) is heated to a temperature equal to or higher than the softening temperature of the thermoplastic liquid crystal polymer film and equal to or lower than 10 ° C. lower than the melting point of the metal roll and the rubber roll having fine irregularities in the range of 5 to 10 μm, The film is subjected to a pressure treatment between them to make the adhesive force between the fine layers existing in the thickness direction of the film 0.5 kg / cm or more. 3) The thermoplastic liquid crystal polymer film Between a pair of heating rolls sandwiching the film with a releasable support having a melting point higher than the melting point of the film, within a temperature range of 10 ° C. lower to 40 ° C. higher than the melting point of the thermoplastic liquid crystal polymer film. The pressure treatment can be performed to make the adhesive force between the fine layers existing in the thickness direction of the film 0.5 kg / cm or more. Without preventing peeling between the fine layers as in the above method, when heat bonding between heating rolls, the adhesive strength of the laminated body after bonding becomes extremely low, but when performing thermal bonding after performing peeling prevention Thus, the adhesive strength of the laminate becomes sufficient. Further, without preventing peeling between the fine layers, the laminate thermally bonded between the heating rolls, due to the difference in the coefficient of thermal expansion with the copper foil, warpage may occur, but if peeling prevention measures are taken Such a problem does not occur.

The material of the metal sheet for circuit used in the present invention is selected from metals and the like used for electrical connection, and examples thereof include gold, silver, copper, nickel and aluminum. Of these, copper is particularly preferred. As the copper, any copper produced by a rolling method or an electrolytic method can be used, but copper having a large surface roughness produced by an electrolytic method is preferable. The metal sheet for a circuit may be subjected to a chemical surface treatment such as acid cleaning usually applied to a copper foil as long as the effects of the present invention are not impaired. The thickness of the metal sheet for a circuit is preferably in the range of 7 to 100 μm.
More preferably, it is within the range of 75 μm.

The bonding between the thermoplastic liquid crystal polymer film and the metal sheet for circuit is performed by applying pressure between a pair of heating rolls. The surface temperature of the heating roll is from 50 ° C. lower than the melting point of the thermoplastic liquid crystal polymer film to 10 ° C. lower than the melting point.
Preferably, it is in the range up to high temperatures. As the material of the heating roll, for example, a metal roll of a dielectric heating type or a heating medium oil circulation type is preferable from the viewpoint of surface temperature uniformity,
A coating layer may be provided on the roll surface. An elastic material such as rubber or a releasable resin material such as polyimide or Teflon is preferably used as the surface coating layer. The diameter of the heating roll is preferably in the range of 35 to 45 cm, and more preferably, the diameter of the pair of heating rolls is almost the same.

In the above method, the pressure applied to the thermoplastic liquid crystal polymer film and the metal sheet for circuit between the heating rolls is 20 kg in terms of surface pressure when using a roll that substantially deforms at the pressurized portion. / Cm
It is preferably at least ² . When using a roll that does not substantially deform at the pressurized part, 5K in linear pressure conversion
g / cm or more is preferable in order to express sufficient adhesive strength between the film and the metal sheet. By doing so, it is possible to suppress the occurrence of spots and to express a sufficient adhesive force.
The upper limit of the pressure is not particularly limited, but in a state where the thermoplastic liquid crystal polymer film does not protrude from the flow or the metal sheet for circuit at the time of pressurization, to sufficiently develop the adhesive force of the laminate, It is desirable that the linear pressure does not exceed 400 kg / cm ² or the surface pressure does not exceed 200 kg / cm ² . When the surface temperature of the heating roll is in a low temperature range, it goes without saying that the flow of the thermoplastic liquid crystal polymer film and the protrusion of the metal sheet disappear even when the pressure is exceeded.

Here, the linear pressure of the heating roll is a value obtained by dividing the force (pressure load) applied to the heating roll by the effective width of the heating roll. In addition, the surface pressure of the heating roll is a value obtained by dividing a pressing load by an area of a pressing surface formed by deformation of the heating roll at the time of pressing.

According to the present invention, in order to obtain a metal-clad laminate having a good appearance and excellent interlayer adhesion and dimensional stability, a thermoplastic liquid crystal polymer film and a metal sheet for a circuit are required to have a melting point of 50% or less. When passing between a pair of heating rolls and press-bonding at a temperature within a range from a temperature lower by 10 ° C. to a temperature higher by 10 ° C. than the melting point, the rotation speed of the heating roll is converted into a linear velocity of 30 m / Minutes or less. In particular, in order to facilitate heat transfer to the circuit metal sheet, it is more preferable to set the speed to 20 m / min or less. The lower limit of the rotation speed of the heating roll is not particularly limited, but if the rotation speed is too low, the production efficiency is reduced. Therefore, it is industrially desirable that the rotation speed is not lower than 0.1 m / min.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the manufacturing method according to the present invention will be described below with reference to the drawings. FIG. 1 shows a method for manufacturing a double-sided metal-clad laminate according to the first embodiment of the present invention. The metal sheets 4 and 4 are wound around the two metal sheet feeding rolls 1 and 1, respectively, and the metal sheets 4 and 4 are supplied from the rolls 1 and 1, respectively.
A thermoplastic liquid crystal polymer film 5 is wound around the film delivery roll 2. The thermoplastic liquid crystal polymer film 5 is formed by a method for preventing separation between fine layers existing in the thickness direction of the above-described thermoplastic liquid crystal polymer film 1) to
According to any of 3), the adhesive force of the fine layer tube existing in the thickness direction of the film is already 0.5 kg / cm or more.

On the upper and lower surfaces of the thermoplastic liquid crystal polymer film 5 delivered from the film delivery roll 2, the metal sheets 4, 4 delivered from the metal sheet delivery rolls 1, 1 are superimposed. , 7 and crimped. The heating rolls 7, 7 are metal rolls of the dielectric heating type. Thus, the metal sheets 4 and 4 are thermally bonded to both surfaces of the thermoplastic liquid crystal polymer film 5 to form the metal-clad laminate 9 and the laminate winding roll 1
Wound to zero. In this way, the thermal bonding between the thermoplastic liquid crystal polymer film 5 and the metal sheets 4 and 4 is continuously performed.

FIG. 2 shows a method for manufacturing a single-sided metal-clad laminate according to a second embodiment of the present invention. This embodiment is different from the first embodiment in that only one metal sheet feeding roll 1 is provided. Therefore, the metal sheet 4 fed from the metal sheet feeding roll 1 is thermally bonded to only one surface of the thermoplastic liquid crystal polymer film 5 to form the single-sided metal-clad laminate 9. In this embodiment, the heating roll 8 on the side of the thermoplastic liquid crystal polymer film 5 has a 1 cm rubber layer as an elastic coating layer on the surface of a dielectric heating type metal roll.

[0030]

EXAMPLES The present invention will be described below in more detail with reference to examples and the like, but the present invention is not limited thereto. In the following Examples and Comparative Examples, the melting point of the thermoplastic liquid crystal polymer film, the adhesive strength of the metal-clad laminate, and the appearance were evaluated as follows.

(1) Melting point The melting point was obtained by observing the thermal behavior of the film using a differential scanning calorimeter. That is, after the temperature of the test film is raised at a rate of 20 ° C./min to completely melt it, the melt is rapidly cooled to 50 ° C. at a rate of 50 ° C./min, and the temperature is raised again at a rate of 20 ° C./min. The position of the endothermic peak that appeared when the recording was performed was recorded as the melting point of the film.

(2) Adhesive strength A peel test specimen having a width of 1.0 cm was prepared from the metal-clad laminate.
The film layer is fixed to a flat plate with double-sided adhesive tape, and JI
The strength when the metal sheet was peeled off at a speed of 50 mm / min was measured by the 180 ° method according to SC 5016.

(3) Appearance The metal-clad laminate is visually observed. If the length of the metal-clad laminate is 200 m or more, air entrapment (the appearance of the metal-clad laminate can be observed as blisters) is good. Those with less than one piece of air entrapment were evaluated as acceptable, and those with one or more pieces of air entrapment per 1 m length and those with unattached portions were observed as poor.

Reference Example 1 p-Hydroxybenzoic acid and 6
-Hydroxy-2-naphthoic acid copolymer having a melting point of 2
A thermoplastic liquid crystal polymer at 80 ° C. was discharged at a discharge rate of 20 kg /
In some cases, melt extrusion was performed, and inflation film formation was performed under the conditions of a transverse stretching ratio of 4.77 times and a longitudinal stretching ratio of 2.09 times. A thermoplastic liquid crystal polymer film having an average thickness of 50 μm and a small thickness distribution of ± 7% was obtained. Prevention of peeling between the fine layers in the thickness direction of the obtained film is performed by sandwiching the film from above and below with a pair of metal rolls heated at 280 ° C.
The heat treatment was performed by continuously heat-treating the Teflon sheet impregnated with the glass woven fabric from the film after continuously performing heat treatment at a linear velocity of 2 m / min. The adhesive strength between the fine layers in the thickness direction of the obtained film was 0.8 kg / cm.

REFERENCE EXAMPLE 2 The film obtained in Reference Example 1 was used as it was without taking measures to prevent separation between fine layers in the thickness direction. The adhesive strength between the fine layers in the thickness direction of the obtained film was 0.2 kg / cm.

Example 1 The thermoplastic liquid crystal polymer film obtained in Reference Example 1 and an electrolytic copper foil having a thickness of 18 μm (surface roughness 7 μm) were arranged as shown in FIG. The surface temperature of the heating roll is set to be 280 ° C., and the pressure applied to the thermoplastic liquid crystal polymer film and the copper foil between the heating rolls is 50 kg / cm in linear pressure conversion. It was 5 m / min. The appearance of the obtained double-sided metal-clad laminate was good, and the adhesive strength was 1.0 kg / cm or more, with no unevenness in the width direction, and was sufficient. Table 6 shows other evaluation results.

Example 2 The thermoplastic liquid crystal polymer film obtained in Reference Example 1 and an electrolytic copper foil having a thickness of 18 μm (surface roughness: 7 μm) were arranged as shown in FIG. The heating roll is a dielectric heating type metal roll and a roll provided with a rubber layer of 1 cm as an elastic coating layer on the surface of the metal roll.
The surface temperature of the heating roll was set to 280 ° C. The pressure applied to the thermoplastic liquid crystal polymer film and the copper foil between the heating rolls is 30 kg / cm ^{2 in} terms of surface pressure.
And the linear velocity on the outer periphery of the heating roll was 5 m / min. The appearance of the obtained single-sided metal-clad laminate is good, and the adhesive strength is 1.0 kg / cm or more without unevenness in the width direction,
Was enough. Table 6 shows other evaluation results.

Comparative Example 1 The thermoplastic liquid crystal polymer film obtained in Reference Example 2 and an electrolytic copper foil having a thickness of 18 μm (surface roughness 7 μm) were arranged as shown in FIG. The heating roll is a dielectric heating type metal roll. The surface temperature of the heating roll is set to be 280 ° C., and the pressure applied to the thermoplastic liquid crystal polymer film and the copper foil between the heating rolls is 50 kg / cm in linear pressure conversion. It was 5 m / min. Although the appearance of the obtained double-sided metal-clad laminate was good, the dimensional stability was poor. Table 6 shows other evaluation results.

[0039]

[Table 6]

[0040]

As described above, according to the present invention, separation between fine layers in the thickness direction of the thermoplastic liquid crystal polymer film can be prevented, the appearance is good, and the thermoplastic liquid crystal polymer film and the metal sheet for a circuit can be formed. A metal-clad laminate having sufficient adhesive strength and excellent dimensional stability can be manufactured.

[Brief description of the drawings]

FIG. 1 is a view schematically showing a method for producing a double-sided metal-clad laminate of the present invention.

FIG. 2 is a view schematically showing a method for producing a single-sided metal-clad laminate of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Delivery roll of a metal sheet, 2 ... Delivery roll of a thermoplastic liquid crystal polymer film, 4 ... Metal sheet, 5
... thermoplastic liquid crystal polymer film, 7, 8 ... heating roll, 9 ... metal-clad laminate, 10 ... laminate winding roll.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B29L 9:00 B29L 9:00 31:34 31:34 F term (Reference) 4F100 AB01B AB17 AB33 AK01A AK01C BA02 BA03 BA06 BA10A BA10C BA13 EJ192 EJ422 GB43 JB16A JB16C JK06 JL04 JN30A JN30C 4F211 AA24C AD03 AD05C AD08C AD29 AH36 TA01 TC04 TD11 TH02 TH03 TH06 TH10 TN09 TQ03

Claims (3)

[Claims] 1. A metal-clad laminate formed by thermally bonding a film made of a thermoplastic polymer capable of forming an optically anisotropic molten phase (hereinafter referred to as a thermoplastic liquid crystal polymer film) and a metal sheet for a circuit. In the method for producing a body, 1) heat-treating the thermoplastic liquid crystal polymer film between a pair of heating rolls so that the adhesive force between the fine layers existing in the thickness direction of the thermoplastic liquid crystal polymer film is at least 0.5 kg / cm), 2) A method for producing a metal-clad laminate, comprising: thermally bonding the circuit metal sheet to one or both surfaces of the thermoplastic liquid crystal polymer film. 2. The method for producing a metal-clad laminate according to claim 1, wherein the thermoplastic liquid crystal polymer film and the circuit metal sheet are continuously subjected to thermal bonding. 3. A metal-clad laminate obtained by the production method according to claim 1.