WO2005037538A1

WO2005037538A1 - Copper-clad laminate

Info

Publication number: WO2005037538A1
Application number: PCT/JP2004/015135
Authority: WO
Inventors: Kazunori Ueda; Katsumi Takata; Katsufumi Hiraishi; Isamu Takarabe
Original assignee: Nippon Steel Chemical Co., Ltd.
Priority date: 2003-10-15
Filing date: 2004-10-14
Publication date: 2005-04-28
Also published as: JP4545688B2; JPWO2005037538A1

Abstract

A copper-clad laminate having sufficient adhesion between a copper foil and a liquid crystal polymer film is disclosed which is suitably used for high-frequency circuit boards or high-density wiring boards. In a copper-clad laminate wherein a copper foil is formed on one side or both sides of an insulating layer composed of a liquid crystal polymer, a copper foil surface which is in contact with the insulating layer has a surface roughness (Rz) of 0.2-3.0 μm, the 180˚ peel strength between the copper foil and the insulating layer at room temperature is not less than 0.5 kN/m, and the insulating layer has a thickness of 10-300 μm. This copper-clad laminate can be obtained by continuously superposing a copper foil on one side or both sides of a liquid crystal polymer using pressure rolls.

Description

Technical field

The present invention relates to a copper-clad laminate having a liquid crystal polymer used for an electronic circuit board as an insulating layer.

Background art

[0002] Liquid crystal polymer films are excellent in high heat resistance, moisture absorption dimensional stability, high-frequency electrical characteristics, etc.

It is known as a material. Focusing on these characteristics of liquid crystal polymer films,

It has been studied for use as an insulating material for electronic circuit boards. When used for an electronic circuit board, a laminate of a liquid crystal polymer film and a metal foil represented by a copper foil is suitable as a laminate for a wiring board.

[0003] Conventionally, when manufacturing a copper-clad laminate used for a printed wiring board or the like using a liquid crystal polymer film, it is extremely difficult to laminate the liquid crystal polymer film and the copper foil and sufficiently obtain the adhesion strength. Met. Therefore, in order to increase the adhesion strength between the liquid crystal polymer film and the copper foil, various studies have been made on a method for producing the laminate (JP-A-4-53739, JP-A-5-42603, JP-A-8-42603). -58024). The following documents are related documents related to the present invention.

Patent Document 1: JP-A-5-345387

[0004] As a method of improving the high adhesion between the copper and the insulating layer, that is, the method of improving the delamination strength of the copper-clad laminate composed of the copper foil and the insulating layer, the use of the copper foil having a large roughness provides an anchor effect. It is known that this is effective in improving the delamination strength. For example, in Patent Document 1, for a laminate having a liquid crystal polymer film and a metal foil layer, a surface in contact with the liquid crystal polymer film has primary irregularities of 6 m or more and primary irregularities. The surface roughness along the surface is 0.4-1.4 / zm. The use of a metal foil with irregularities that also has a secondary uneven force makes it difficult for peeling to occur not only under normal peel strength but also under bending conditions. It is described that a laminate can be obtained.

[0005] Under recent demands for lightness, small size, high speed transmission, and the like of electronic devices, the roughness shown in Patent Document 1 Even if a copper foil with a large surface roughness is used, there are problems such as the inability to process the conductor layer at a fine pitch and poor signal transmission characteristics in the high frequency range. Thus, a laminate having good delamination strength with a liquid crystal polymer film is required. However, there is a problem that it is extremely difficult to obtain the adhesion strength by the anchor effect with the copper foil having a small roughness, and there is a problem that the roughness is small with the liquid crystal polymer film by the conventional technology. Disclosure of the Invention There was a problem that a sufficient adhesion strength could not be obtained even as a laminate.

Problems to be solved by the invention

An object of the present invention is to provide a copper-clad laminate having a sufficient adhesive strength between a copper foil and a liquid crystal polymer film. Another object of the present invention is to provide a copper-clad laminate used suitably for a high-frequency circuit board or a high-density wiring board.

Means for solving the problem

That is, the present invention relates to a copper-clad laminate in which a copper foil is provided on one or both sides of an insulating layer made of a liquid crystal polymer, the surface roughness (Rz) of the surface of the copper foil in contact with the insulating layer is 0.2 A copper-clad laminate having a 180 ° delamination strength of at least 0.5 kN / m between the copper foil and the insulating layer at room temperature. In addition, the present invention superimposes a copper foil having a surface roughness (Rz) force of 3.0 μm on a surface in contact with the insulating layer of the copper foil on one or both sides of the insulating layer which also has a liquid crystal polymer force, This is a method for producing the copper-clad laminate, which is continuously bonded and laminated by a pressure roll heated to a temperature lower than the melting point of the polymer film in the range of 5 to 100 ° C.

[0008] The laminate of the present invention has at least one layer in which an insulating layer having liquid crystal polymer strength and a copper foil layer having a surface roughness of 0.2 to 3.0 m are bonded, and the 180 ° delamination strength of the bonded portion is provided. Is more than 0.5 kN / m.

[0009] The liquid crystal polymer used in the present invention is any liquid crystal polymer capable of forming an optically anisotropic molten phase, and is also called a thermopick liquid crystal polymer. A polymer capable of forming an optically anisotropic molten phase is well known to those skilled in the art, and is obtained by observing a sample in a molten state under a polarizing microscope equipped with a heating device. Transmission of polarized light High quality polymer.

[0010] The liquid crystal polymer is not particularly limited, but for example, aromatic hydroxycarboxylic acid, aromatic dicarboxylic acid, aromatic diol, aromatic hydroxyamine, aromatic diamine, aromatic aminocarboxylic acid, and the like. Selected monomers, particularly aromatic dicarboxylic acids, aromatic diols, and aromatic hydroxycarboxylic acids. Examples include liquid crystalline polyester resins or polyesteramides that form an anisotropic molten phase having structural units derived from the selected monomers. Can be

[0011] Specific examples of the aromatic hydroxycarboxylic acid include, for example, 4-hydroxybenzoic acid, 3-hydroxybenzoic acid, 2-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, and 3-hydroxy-2-naphthoic acid. Acid, 4'-hydroxyphenyl-4-benzoic acid, 3'-hydroxyphenyl-4-benzoic acid, 4-hydroxyphenyl-3-benzoic acid and alkyl, alkoxy or halogen-substituted products thereof. In addition, these ester-forming derivatives may be mentioned. Of these, 4-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid are preferred because they can easily adjust the properties and melting point of the polymer obtained.

Specific examples of aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 1,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, and 4,4′-dicarboxylic acid Carboxybiphenyl, bis (4-carboxyphenyl) ether, bis (4-carboxyphenyl) butane, bis (4-carboxyphenyl) ethane, bis (3-carboxyphenyl) ether And aromatic dicarboxylic acids such as bis (3-carboxyphenyl) ethane and the like, alkyl, alkoxy and halogen-substituted derivatives thereof, and ester-forming derivatives thereof.

[0013] Specific examples of the aromatic diol include 4,4'-dihydroxybiphenyl, 3,3'-dihydroxybiphenyl, 3,4'-dihydroxybiphenyl, and 4,4'-dihydroxydiphenylethanol. , Bis (4-hydroxyphenyl) ethane, hydroquinone, resorcinol, 2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, 1,6-dihydroxynaphthalene and other aromatic diols and their alkyl, alkoxy or halogen substitution In addition to the body, these ester-forming derivatives can be mentioned.

Note that an ester-forming derivative is a compound having the ability to react to form an ester. O

[0014] Specific examples of aromatic hydroxyamine, aromatic diamine, and aromatic aminocarboxylic acid include the following compounds.

For example, aromatic hydroxyamines include 4-aminophenol, N-methyl-4-aminophenol, 3-aminophenol, 3-methyl-4-aminophenol, 4-amino-1-naphthol, 4 -Amino-4'-hydroxybiphenyl, 4-amino-4'-hydroxydiphenyl ether, 4-amino-4'-hydroxydiphenylmethane, 4-amino-4'-hydroxybiphenyl sulfide And aromatic hydroxyamines.

[0015] Examples of aromatic diamines include 1,4-phenylenediamine, N-methyl-1,4-phenylenediamine, Ν, Ν'-dimethyl-1,4-phenylenediamine, and 4,4'-diaminodiphene. -Rusulfide (also known as thiodiarin), 2,5-diaminotoluene, 4,4'-ethylenedianiline, 4,4'-diaminodiphenoxetane, 4,4'-diaminodiphenylmethane (also known as methylenediarin) , 4,4'-diaminodiphenyl ether (alias: oxidiarin) and the like.

[0016] Examples of the aromatic aminocarboxylic acid include 4-aminobenzoic acid, 2-amino-6-naphthoic acid, 2-amino-7-naphthoic acid, and the like.

The aromatic hydroxyamine, aromatic diamine and aromatic aminocarboxylic acid described above include their ester-forming derivatives or imide-forming derivatives.

The raw material monomers for the liquid crystal polymer used in the present invention include, in addition to the monomers exemplified above, alicyclic dicarboxylic acids, aliphatic diols, alicyclic diols, aromatic mercaptocarboxylic acids, aromatic dithiols, aromatic dithiols, and aromatic dithiols. It is natural that group mercaptophenol and the like can be used in a range that does not hinder the formation of the liquid crystal polymer.

[0018] Specific examples of the alicyclic dicarboxylic acid, the aliphatic diol and the alicyclic diol include hexahydroterephthalic acid, trans-1,4-cyclohexanediol, and cis-1,4-cyclohexanediene. All, trans-1,4-cyclohexanedimethanol, cis-1,4-cyclohexanedimethanol, trans-1,3-cyclohexanediol, cis-1,2-cyclohexanediol, trans-1 Linear or branched aliphatic diols such as 1,3-cyclohexanedimethanol, ethylene glycol, 1,3-propanediol, 1,4-butanediol, and neopentyldaricol, and their ester formation Sex derivatives. [0019] Specific examples of aromatic mercaptocarboxylic acid, aromatic dithiol, and aromatic mercaptophenol include 4-mercaptobenzoic acid, 2-mercapto-6-naphthoic acid, 2-mercapto-7-naphthoic acid, benzene- 1,4-dithiol, benzene-1,3-dithiol, 2,6-naphthalenedithiol, 2,7-naphthalene-dithiol, 4-mercaptophenol, 3-mercaptophenol, 6-mercaptophenol, etc. Ester (including thioester) forming derivatives thereof may be mentioned.

[0020] In order to obtain a polymer capable of forming an optically anisotropic molten phase, it is needless to say that there is an appropriate range for each combination of raw material compounds.

[0021] Specific examples of the liquid crystal polymer obtained from these starting compound (monomer) powers include polymers having the following structural units.

4-hydroxybenzoic acid Z6-hydroxy-2-naphthoic acid copolymer,

4-hydroxybenzoic acid Z terephthalic acid Ζ4,4'-dihydroxybiphenyl copolymer, 4-hydroxybenzoic acid Ζterephthalic acid Ζisophthalic acid Ζ4,4'-dihydroxybiphenyl copolymer,

4-hydroxybenzoic acid Ζ6-hydroxy-2-naphthoic acid Ζterephthalic acid Ζhydroquinone copolymer,

4-hydroxybenzoic acid Ζ6-hydroxy-2-naphthoic acid Ζ2,6-naphthalenedicarboxylic acid ハイドロ hydroquinone copolymer,

4-hydroxybenzoic acid terephthalic acid 4-aminophenol copolymer,

4-hydroxybenzoic acid Ζ6-hydroxy-2-naphthoic acid Ζterephthalic acid Ζ4-aminophenol copolymer,

4-hydroxybenzoic acid Ζterephthalic acid Ζ4,4'-dihydroxybiphenyl Ζ4-aminophenol copolymer,

4-hydroxybenzoic acid 酸 terephthalic acid Ζethylene glycol copolymer.

The liquid crystal polymer used in the present invention has a transition temperature to an optically anisotropic molten phase within the range of 200 to 400 ° C., particularly 250 to 350 ° C. in terms of heat resistance and processability. It is preferred to have one. In addition, lubricants, antioxidants, fillers, etc. should be added as long as the properties of the film are not impaired. May be combined.

The liquid crystal polymer used in the present invention is advantageously adhered to a copper foil in the form of a film or a force film that can be used by applying a solution.

[0023] The liquid crystal polymer film used in the present invention is obtained by a known method such as extrusion molding.

In the case of extrusion molding, any extrusion molding method can be applied, but the well-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, the stress is applied only in the machine axis direction (hereinafter, MD direction) of the film and in the direction perpendicular to this direction (hereinafter, TD direction). The resulting film has a good balance of mechanical properties.

[0024] A preferred thickness range of the liquid crystal polymer film is 500 µm or less, more preferably 5 to 400 µm, and particularly preferably 10 to 300 µm. If the film thickness is less than 10 μm, the film will tear easily and handling will be difficult. If it exceeds 500 m, the film will become rigid and difficult to roll into a roll, making handling difficult.

[0025] As the copper foil used in the present invention, any one produced by a rolling method or an electrolysis method can be used. For the purpose of securing the adhesive strength between the copper foil and the liquid crystal polymer film, a physical surface treatment such as a roughening treatment or a chemical surface treatment such as an acid cleaning is performed within a range where the effect of the present invention is not impaired. You can give it!

[0026] The preferred thickness range of the copper foil is 5 to 150 µm, more preferably 10 to 70 µm, and particularly preferably 10 to 35 µm. Reducing the thickness of the copper foil is preferable from the viewpoint that a fine pattern can be formed.However, if the thickness is too small, the copper foil may be wrinkled in the manufacturing process, and a circuit may be formed as a wiring board. In this case, the wiring may be broken or the reliability of the circuit board may be reduced. On the other hand, when the thickness of the copper foil is increased, when etching the copper foil, the side surface of the circuit is tapered, which is not preferable in forming a fine pattern.

[0027] In the present invention, the surface roughness of the copper foil and the elemental components on the roughened surface are important. The surface roughness is such that Rz measured according to JIS B 0601 is in the range of 0.2 to 3.0 μm, preferably 0.5 to 2.5 μm. When Rz is greater than 3.0 m, the adhesion strength between copper insulating layers is easily obtained, but the following problems occur. Fine pitching of conductive layer by etching However, problems such as increased taper on the side of the circuit, making it impossible to ensure a uniform width between the conductor and the gap, and an increase in the residual copper component, resulting in poor insulation between the conductors, etc.

. In the case of signal transmission in the high frequency range where the frequency is in the GHz band, current flows only on the surface of the conductor pattern called the skin effect. A problem occurs in signal propagation.

Further, when Rz is lower than 0.2 / zm, it is extremely difficult to obtain high adhesion strength even by the method of the present invention, and when a conductor is processed, circuit peeling or soldering may occur. Problems such as swelling and peeling occur during heat treatment.

[0028] Further, in that high adhesion strength is obtained by using a copper foil having an Rz in the range of 0.2 to 3.0 m, the surface of the copper foil in contact with the insulating layer is made of nickel, cobalt, chromium, in addition to copper. It is preferable to use a copper foil containing at least one element selected from sulfur and sulfur, since high adhesion strength is maintained, and peeling or swelling hardly occurs even in a subsequent circuit processing or soldering step.

More preferably, the surface of the copper foil in contact with the insulating layer is formed of copper nickel cobalt, copper nickel-cobalt chromium, copper-nickel cobalt sulfur, copper nickel cobalt-chromium-sulfur, copper cobalt chromium, or copper-cobalt chromium sulfur. It is preferable to be constituted by a combination of the above elements for the same reason as described above.

The measurement of the material constituent elements on the surface of the copper foil in contact with the insulating layer is measured by an energy dispersive X-ray analyzer (EDX), and more specifically, according to the method described in Examples.

[0029] In the method for producing a laminate of the present invention, a liquid crystal polymer film and a copper foil are overlaid, bonded by thermocompression bonding, and laminated. The thermocompression bonding is performed between pressurizing rolls from the viewpoint of uniformity of the bonding state, and it is usually preferable to use a pair of metal pressurizing rolls or a rubber pressurized metal pressurizing roll. If the laminate of the present invention is thermocompression-bonded using a batch-type vacuum press device having a flat metal heat plate at the top and bottom, the resulting laminate has low adhesion strength and uniform bonding. The problem of having no state may occur.

[0030] The forms of the liquid crystal polymer film and the copper foil used here can be any from the viewpoint of productivity. Is also preferably in the form of a roll. These are continuously conveyed by a roll 'edge' roll, and are pressure-bonded in the process, thereby achieving a process with good productivity.

[0031] The surface of the metal pressure roll needs to be heated by some means. Although there is no particular limitation on the method, heating by a dielectric heating method ゃ heating medium circulation method can be exemplified. In the present invention using a metal roll, it is convenient to provide a heating mechanism inside the metal roll, thereby heating the roll surface. The surface temperature of the roll is preferably 5-100 ° C lower than the melting point of the liquid crystal polymer film, more preferably 20-80 ° C lower than the melting point! If the surface temperature of the heating roll is lower than the melting point of the film by more than 80 ° C, the film and the copper foil may not be sufficiently bonded. On the other hand, if the surface temperature of the heating roll exceeds 5 ° C. lower than the melting point of the film, the flow of the film at the time of press bonding becomes remarkable, resulting in a laminate having poor appearance.

[0032] The melting point of the liquid crystal polymer film is a melting peak temperature in differential scanning calorimetry (DSC) when the film to be subjected to thermocompression bonding is heated at a heating rate of 10 ° CZ. .

The pressure at the time of press bonding is not particularly limited as long as it can be uniformly pressed in the width direction, but is preferably 5 to 200 kN / m, more preferably 70 to 120 kN / m.

[0033] In the laminate of the present invention, at least one bonding surface is a bonding surface between the liquid crystal polymer and the copper foil, and the 180 ° delamination strength of the bonding surface between the copper foil and the insulating layer at room temperature is normal. A force that needs to be at least 0.5 kN / m should be in the range of 0.5—10 kN / m. Preferably, it is 0.5 to 5 kN / m, more preferably 0.5 to 2.5 kN / m, and still more preferably 0.7 to 2.0 kN / m.

[0034] The laminate of the present invention is not limited to a two-layer structure of a liquid crystal polymer film and a copper foil. That is, it is sufficient that the laminate contains at least one layer of a liquid crystal polymer film and at least one layer of copper foil.For example, a three-layer structure shown in I) -III) below, a four-layer structure of IV), The five-layer structure of V) can be exemplified. In the following I) -1 V), in the case of a laminate having two or more films, at least one film in contact with the copper foil is a liquid crystal polymer film. Advantageously, it is good that all the bonding surfaces of the copper foil and the film satisfy the above Rz and delamination strength.

[0035] I) Copper foil Z film Z copper foil in) Film Z Copper foil Z film

iv) Copper foil Z film Z film Z copper foil

v) Copper foil Z film Z copper foil Z film Z copper foil

According to the present invention, it is possible to simultaneously bond a film and a copper foil on two or more surfaces. For example, one copper foil is laminated on both surfaces of one film. By performing pressure bonding in the bent state, it is possible to manufacture a laminate having a three-layer structure of copper foil Z film Z copper foil.

The copper-clad laminate of the present invention uses a low-roughness copper foil having a small surface roughness and has a sufficient adhesive strength to a liquid crystal polymer film, so that fine pitch processability and signal in a high frequency region can be achieved. It has features such as low transmission loss and has reliability as a circuit board material. The copper-clad laminate of the present invention is particularly useful as a material suitable for use in high-frequency circuit boards and high-density wiring boards.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described in detail with reference to examples. The present invention is not limited to these examples. The evaluation of the copper-clad laminates in Examples and Comparative Examples was performed by the following method.

[0038] 1) Copper foil surface roughness (Rz): According to JIS B 0601, using a stylus type surface roughness measuring device (TENCOR P-10 manufactured by TENCOR) under the condition of a measuring width of 200 m Was measured.

2) Elemental analysis of copper foil surface: energy dispersive X-ray analyzer (Horiba, Ltd.)

The measurement was performed under the conditions of an acceleration voltage of 15 kV and a magnification of 1000 times using EMAX400). At this time, the composition ratio was calculated from the detected intensity ratio so that the total composition ratio of the elements detected other than copper was 100, and those having a composition ratio of the elements other than copper of 0.1% or more were defined as the element-containing components.

3) Delamination strength: According to JIS C 6471, a copper foil having a width of lmm was peeled at 180 ° with respect to the copper foil removed surface, and the delamination strength at room temperature was measured. The delamination strength was measured on three or more test pieces arbitrarily collected from the copper-clad laminate, and the average value was recorded.

4) Fine pitch workability: Laminate a dry film on a copper-clad laminate and create a circuit pattern by UV exposure using a pattern film with a resist width of 50 m and a circuit width of 50 μm. It was. Next, this was etched using a copper chloride etching solution. The resulting wiring pattern was observed with an optical microscope for peeling of the circuit and for the presence of residual copper between the circuits.

Example 1

18 μm thick electrolytic copper foil (Rz = 2.3) on both sides of a 50 m thick liquid crystal polymer film (made of Kuraray clay, trade name Vexter, melting point 280 ° C, 4-hydroxybenzoic acid Z6-hydroxy-2-naphthoic acid copolymer) μm, elemental components: Ni 75.2%, Co 24.7%), and continuously supplied between a pair of metal press rolls (diameter 250mm) heated to 210 ° C at a surface temperature of lmZ. The pressure was increased to 150 kN / m to produce a copper-clad laminate. The liquid crystal polymer film and the electrolytic copper foil were made from rolls. Table 1 shows the evaluation results of the obtained copper-clad laminate.

Example 2—5

A copper-clad laminate was manufactured and evaluated in the same manner as in Example 1 except that an electrolytic copper foil having a thickness of 18 m and having an roughness Rz and an elemental component shown in Table 1 was used. did.

Comparative Example 1-1 2

[0042] Table 1 shows the roughness Rz, the elemental components and the composition ratios of the copper foils used in the examples and comparative examples. Table 1 summarizes the evaluation results.

[Table 1]

Roughness Constituent element Delamination Fine pi Rz, Zo No.

(m) (N / mm) Example 1 2.3 Ni (75.2), Co (24.7) 1.6 Good Example 2 0.9 Cr (34.0), Co (60.1) , S (5.8) 1.1 Good Example 32.1 Cr (99.9) 1.4 Good Example 42.3 Ni (95.0), Zn (5.0) 1.0 Good Example 5 0.9 Ni (30.4), Co (67.7), Cr (1.9) 0.9 good Comparative Example 1 6.0 Zn (99.9) 1.5 Copper remaining Comparative Example 2 0.1 Sn (100. 0) 0.2 Exfoliation

Industrial applicability

The copper-clad laminate of the present invention and the copper-clad laminate obtained by the production method of the present invention are particularly useful as materials suitable for use in high-frequency circuit boards and high-density wiring boards. Also, it has excellent fine pitch workability.

Claims

The scope of the claims

[1] In a copper-clad laminate in which a copper foil is provided on one or both surfaces of an insulating layer having a liquid crystal polymer, the surface roughness (Rz) of the surface of the copper foil in contact with the insulating layer is 0.2 to 3.0 m. A copper-clad laminate characterized by having a 180 ° delamination strength between the copper foil and the insulating layer at room temperature of 0.5 to 5 kN / m.

[2] The copper-clad laminate according to claim 1, wherein the thickness of the insulating layer is in the range of 10 to 300 m.

[3] When the surface material of the copper foil in contact with the insulating layer is measured by an energy dispersive X-ray analyzer (EDX), at least one or more of nickel, cobalt, chromium, and sulfur are selected in addition to copper. 3. The copper-clad laminate according to claim 1, containing an element.

[4] The copper foil surface material is composed of any combination of the following elements: copper nickel cobalt, copper nickel cobalt chromium, copper-nickel cobalt sulfur, copper nickel cobalt chromium sulfur, copper cobalt chromium, and copper cobalt chromium sulfur. 4. The copper-clad laminate according to claim 3, wherein:

[5] The method for producing a copper-clad laminate according to any one of [14] to [14], wherein one or both surfaces of the liquid crystal polymer insulating layer have a surface roughness (Rz) of a surface in contact with the copper foil insulating layer. Copper foil with a range of 0.2-3.0 m is laminated and continuously bonded and laminated by a pressure roll pre-heated to a low temperature of 5-100 ° C, the melting point of the liquid crystal polymer film. A method for manufacturing a copper-clad laminate.