insulating film and laminate containing the same

Abstract

This application relates to an insulating film and a laminate including the same. The insulating film not only has excellent adhesion to a metal layer laminated therewith, but also has excellent heat resistance and film-forming properties. Such an insulating film can be used in the manufacture of a laminate such as an FCCL together with a metal layer containing copper, and can be suitably used for components for fifth-generation mobile communications.

Description

[Technical Field]

[0001] Cross-reference of related applications This application claims priority rights under Korean Patent Application No. 10-2022-0106433 dated August 24, 2022, and Korean Patent Application No. 10-2023-0103406 dated August 8, 2023, and all content disclosed in the documents of said Korean Patent Applications is incorporated herein by reference.

[0002] This application relates to an insulating film and a laminate containing the same. [Background technology]

[0003] 5G, referring to the fifth generation of mobile communication, is a core infrastructure of the Fourth Industrial Revolution that transmits vast amounts of data at ultra-high speeds and connects everything in real time (ultra-low latency) compared to the existing fourth-generation mobile communication, LTE (Long-Term Evolution). The biggest challenge in such 5G mobile communication technology is reducing transmission loss. 5G uses a high-frequency range (short-wavelength range) with high directivity, but in this case, the proportion of radio waves absorbed by materials during their movement (transmission loss ratio) is high. Therefore, semiconductors and PCBs (Printed Circuit Boards) for 5G mobile communication require low dielectric constant characteristics that can reduce transmission loss, and insulators using liquid crystal polymer resins are mainly being considered to ensure low dielectric constant characteristics.

[0004] On the other hand, despite possessing various strengths such as high strength, high heat resistance, and low water absorption, in addition to the low dielectric properties mentioned above, liquid crystal polymer films face challenges in commercializing them. This stems from the properties of liquid crystal polymer resins. Specifically, because liquid crystal polymer resins form a liquid crystal structure in a molten state, they have high orientation characteristics in the flow direction. As a result, during film manufacturing, the film tears in the direction of discharge from the die, and dimensional stability is poor (dimensionally non-uniform), making it difficult to ensure film formation.

[0005] To improve the shortcomings of the liquid crystal polymer films described above, Japanese Patent No. 4091209 attempts to improve the thermal insulation strength and lateral vibration of bubbles (film-forming properties) of the film by applying polyarylate, an amorphous polymer. Furthermore, Japanese Patent No. 3896324 attempts to improve dimensional stability by applying thermoplastic resins (PEI, PES, PPS, and polyarylate). Thus, conventional attempts such as those described in the aforementioned patent documents focus on improving the film-forming properties of liquid crystal polymer films.

[0006] However, when using amorphous polymers or thermoplastic resins, such as those containing polyarylates, as mentioned in the aforementioned patent documents, the adhesive strength decreases due to an increase in melt viscosity, which can lead to poor adhesion between the LCP (Liquid Crystal Polymer) film and the copper foil during the manufacturing process of FCCL (Flexible Copper Clad Laminate). Therefore, further improvement is needed. [Overview of the project] [Problems that the invention aims to solve]

[0007] One of the objectives of this application is to resolve the problems of the prior art described above.

[0008] Another object of this application is to provide a liquid crystal polymer film with improved adhesion to copper foil.

[0009] The above-mentioned and other objectives of this application can all be resolved by the invention described in detail below. [Means for solving the problem]

[0010] According to one embodiment of the present invention, an insulating film for forming an FCCL (Flexible Copper Clad Laminate) by being laminated with a copper-containing metal layer, An insulating film is provided that satisfies a surface roughness ratio of 78% or more, calculated by the following relational formula:

[0011] [Relationship] Surface roughness ratio (%) = (S r2 / S r1 ) × 100 (In the above relational expression, S r1 This is the arithmetic mean roughness of any one surface of the metal layer that forms FCCL together with the insulating film, and is in the range of 0.1 to 0.6 μm. S r2 This is the arithmetic mean roughness of any one surface of the insulating film, measured after immersing the insulating film or the FCCL in an iron(III) chloride anhydrous (FeCl3·6H2O) solution and washing it for 1 hour. The aforementioned arithmetic mean roughness was measured using a cutoff of 800 μm.

[0012] According to another embodiment of the present invention, there is a laminate comprising (A) a metal layer containing copper; and (B) an insulating film located on at least one surface of the metal layer, wherein the insulating film satisfies a surface roughness ratio of 78% or more calculated by the relational formula.

[0013] The following describes in more detail an insulating film and a laminate containing the same according to one embodiment of the invention.

[0014] Unless otherwise expressly stated herein, technical terms are used solely to refer to specific embodiments and are not intended to limit the invention.

[0015] As used herein, the singular form includes the plural form unless the wording explicitly indicates the opposite.

[0016] As used herein, the meaning of "comprising" embodies specific characteristics, regions, integers, steps, operations, elements and / or components, and does not exclude the presence or addition of other specific characteristics, regions, integers, steps, operations, elements, components and / or groups.

[0017] Although the present invention can be subject to various modifications and can have various forms, specific embodiments will be illustrated and described in detail below. However, this is not intended to limit the present invention to specific disclosed forms, and it should be understood that all modifications, equivalents or alternatives included within the above-mentioned idea and technical scope are encompassed.

[0018] According to specific examples of the present application, an insulating film (or liquid crystal film) that solves the above-mentioned problems of the prior art and has improved adhesive force to a copper foil, and a laminate including the same are provided.

[0019] In relation to this, the inventors of the present application have confirmed that a liquid crystal polymer film manufactured by applying a polyarylate resin has a certain effect on improving the film-forming property of the liquid crystal polymer film, but the adhesive force between the liquid crystal polymer film and the copper foil becomes low. Specifically, the inventors of the present application have found that the conventional manufacturing method of a liquid crystal polymer film increases the viscosity of the resin composition by applying a polyarylate resin, thereby reducing the wetting ability during the adhesion process with the copper foil and resulting in insufficient adhesion between the copper foil and the insulating film, and thus determined that such problems occur, and completed the invention of the present application to solve this problem.

[0020] Therefore, according to one embodiment of the invention, an insulating film for forming an FCCL (Flexible Copper Clad Laminate) by being laminated with a metal layer containing copper, an insulating film can be provided that satisfies a surface roughness ratio calculated by the following relational expression of 78% or more:

[0021] [Relational Expression] Surface roughness ratio (%) = (S r2 / S r1 ) × 100 (In the above relational expression, S r1 This is the arithmetic mean roughness of any one surface of the metal layer that forms FCCL together with the insulating film, and is in the range of 0.1 to 0.6 μm. S r2 This is the arithmetic mean roughness of any one surface of the insulating film, measured after immersing the insulating film or the FCCL in an iron(III) chloride anhydrous (FeCl3·6H2O) solution and washing it for 1 hour. The aforementioned arithmetic mean roughness was measured using a cutoff of 800 μm.

[0022] In a specific example relating to this application, this application relates to an insulating film.

[0023] This application describes how to suppress the viscosity increase of a resin composition and improve adhesion to copper foil by using a resin composition containing a polyarylate resin and at least two types of liquid crystal polyesters, and by adjusting the mixing ratio thereof. In one embodiment, the two or more types of liquid crystal polyesters may include low-melting-point and high-melting-point liquid crystal polyester resins with different melting points. Therefore, this application can provide an insulating film for forming FCCL (Flexible Copper Clad Laminate) with an excellent surface roughness ratio and a laminate containing the same.

[0024] In other words, the insulating film can be used for applications in which it is laminated with a copper-containing metal layer to form FCCL (Flexible Copper Clad Laminate), and can have properties suitable for such applications (e.g., properties that can solve the problems of the conventional technology described above). Specifically, the insulating film can satisfy the surface roughness described later and is formed from the components described later.

[0025] In a specific example of the present application, the insulating film satisfies that the ratio of the surface roughness calculated by the following relational expression is 78% or more.

[0026] [Relational Expression] Ratio of surface roughness (%) = (S r2 / S r1 ) × 100

[0027] In the above relational expression, S r1 can mean the arithmetic mean roughness of any one surface of the metal layer that forms the FCCL together with the insulating film. At this time, any one surface of the metal layer where the S r1 is measured can mean, for example, when manufacturing FCCL, one surface of the metal layer that faces or contacts the insulating film. When manufacturing FCCL, any one surface of the metal layer (copper foil) laminated together with the insulating film generally has an arithmetic mean roughness (S r1 ) of 0.1 μm or more, 0.2 μm or more, 0.3 μm or more, 0.4 μm or more, or 0.5 μm or more, and 0.6 μm or less, 0.5 μm or less, 0.4 μm or less, 0.3 μm or less, or 0.2 μm or less.

[0028] In the above relational expression, S r2 can mean the arithmetic mean roughness of any one surface of the insulating film. At this time, any one surface of the insulating film where the S r2 is measured can mean, for example, when manufacturing FCCL, one surface of the insulating film that faces or contacts the metal layer (e.g., copper foil). According to a specific example of the present application, the S r2 can be measured after immersing and washing the insulating film or the FCCL (formed by laminating the insulating film and the metal layer) in an iron(III) chloride (FeCl3·6H2O, Iron(III) Chloride anhydrous) solution within 1 hour. Although not particularly limited, the concentration of the iron(III) chloride solution (that is, the weight percentage of iron(III) chloride excluding the solvent in 100% by weight of the solution) can be 90% or more or 95% or more, and 100% or less.

[0029] In the specific example of this application, such arithmetic mean roughness may be measured using a cutoff of 800 μm. And, without being particularly limited, such arithmetic mean roughness can be measured using known devices such as an optical surface roughness meter (3D Profiler).

[0030] In relation to the problems of the conventional technology described above, such as the decrease in adhesive strength due to the increase in the melt viscosity of the insulating film, the inventors of this application have experimentally confirmed that the decrease in adhesive strength can be prevented if the surface roughness of the insulating film is designed to be similar to the surface roughness of the metal layer (e.g., copper foil). Specifically, as can be seen from the experiment below, if the adhesive strength between the metal layer (e.g., copper foil) on which FCCL is formed and the insulating film is insufficient, there is a large difference between the surface roughness of the insulating film and the surface roughness of the copper foil before etching. Therefore, it is necessary to design the insulating film so that the surface roughness of the insulating film (during or after etching) follows the surface roughness of the copper foil before etching to a certain extent or more. As an example of such a design, control the viscosity (melt viscosity) of the insulating film to 1,000 poise or less, as described later.

[0031] In one example, the lower limit of the surface roughness ratio calculated by the above relational formula may be 79% or more, 80% or more, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, 87% or more, 88% or more, 89% or more, 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, 98% or more, or 99% or more. The upper limit may be, for example, 100% or less, specifically 99% or less, 98% or less, 97% or less, 96% or less, or 95% or less.

[0032] In one example, the insulating film may have a film viscosity of 1,000 poise or less. In another example, the insulating film may have a film viscosity of 300 to 1,000 poise or less (provided that the film viscosity is measured at 320°C and a shear rate of 500 / sec). Such viscosity satisfies the surface roughness ratio calculated by the above relation and prevents a decrease in the adhesion strength of the insulating film to the copper foil. Furthermore, such viscosity allows for a higher adhesion strength than that expected when using polyarylate as a component of the insulating film in the prior art.

[0033] For example, the lower limit of the film viscosity of the insulating film may be 300 poise or more, 350 poise or more, 400 poise or more, 450 poise or more, 500 poise or more, 550 poise or more, 600 poise or more, 650 poise or more, 700 poise or more, 750 poise or more, 800 poise or more, 850 poise or more, 900 poise or more, or 950 poise or more. The upper limit may be, for example, 950 poise or less, 900 poise or less, 850 poise or less, 800 poise or less, 750 poise or less, 700 poise or less, 650 poise or less, 600 poise or less, 550 poise or less, 500 poise or less, 450 poise or less, 400 poise or less, or 350 poise or less.

[0034] The insulating film may be formed or manufactured to satisfy at least the above-mentioned surface roughness ratio and / or film viscosity.

[0035] In this regard, according to a specific example of the present application, the insulating film may include a polyarylate and a liquid crystal polymer resin. More specifically, the insulating film may be manufactured from a composition comprising a polyarylate and a liquid crystal polymer resin. Even more specifically, the insulating film may be manufactured from a composition comprising a polyarylate and two or more liquid crystal polymer resins (more preferably two or more liquid crystal polyester resins having different melting points).

[0036] For example, the insulating film can be formed by melt-molding a composition containing insulating film-forming components. Specifically, the insulating film can be obtained by melt-kneading a composition containing polyarylate and liquid crystal polymer resin in an extruder and extruding the molten resin through the slits of a die. A T-type die or a circular die may be used in this process.

[0037] In some cases, the extruded insulating film may be stretched. Possible stretching methods include known techniques such as uniaxial stretching, biaxial stretching, inflation stretching, or laminate stretching.

[0038] In another example, an insulating film laminate may be formed by simultaneously forming an insulating film with a die slit and joining dissimilar thermoplastic polymer films. In this case, usable dissimilar thermoplastic polymers include polyolefins such as polyethylene, polypropylene, and ethylene-α-olefin copolymers; or polyesters such as polystyrene, polycarbonate, polyethylene terephthalate, and polybutylene terephthalate. Other usable materials include polyacetal, polyamide, polyphenylene ether, polyethersulfone, ethylene-vinyl acetate copolymer, polyvinyl chloride, polyvinylidene chloride, polyphenylene sulfide, and fluororesins.

[0039] The polyarylate used in forming the insulating film is an aromatic polyester produced by condensation polymerization of an aromatic dicarboxylic acid and an aromatic diol, and its specific structure is not particularly limited as long as it does not interfere with satisfying the above-mentioned film viscosity, elastic modulus, and / or relational formulas. The polyarylate functions advantageously in improving the moldability or film-forming properties of the insulating film.

[0040] On the other hand, as mentioned above, while an amorphous polymer, such as polyallylate, can be used to improve the film-forming properties of insulating films, polyallylate with high viscosity exhibits poor flowability during the bonding process between the insulating film and the metal layer (e.g., copper foil) by heat bonding. This can prevent the resin from sufficiently penetrating the surface of the copper foil, leading to a decrease in adhesive strength between the insulating film and the metal layer. Therefore, it is preferable to select a liquid crystal polymer resin to prevent the decrease in adhesive strength that occurs when using polyallylate resin.

[0041] The liquid crystal resin or liquid crystal polymer used in forming insulating films refers to a polymer that maintains a crystalline state in the molten state and exhibits liquid crystalline properties. The chemical composition and structure of the liquid crystalline polymer are not particularly limited, as long as they do not interfere with satisfying the surface viscosity ratio and / or film viscosity of the above-described relation.

[0042] For example, the liquid crystal polymer may contain one or more liquid crystal polymers such as thermoplastic liquid crystal polyester or thermoplastic liquid crystal polyesteramide in which an amide bond is introduced thereto.

[0043] Alternatively, the liquid crystal polymer may include one or more polymers in which an imide bond, a carbonate bond, a carbodiimide bond, or an isocyanate-derived bond such as an isocyanurate bond has been additionally introduced to an aromatic polyester or aromatic polyesteramide.

[0044] In one example, the thermoplastic liquid crystal polyester can be produced from aromatic hydroxycarboxylic acids, aromatic dihydroxys, aromatic dicarboxylic acids, aromatic diamines, aromatic hydroxyamines, and / or aromatic aminocarboxylic acid monomers.

[0045] The aforementioned aromatic hydroxycarboxylic acid monomers are not limited to these, but may include, for example, 2-hydroxybenzoic acid, 3-hydroxybenzoic acid, 4-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, 5-hydroxy-2-naphthoic acid, 3-hydroxy-2-naphthoic acid, 4-(4-hydroxyphenyl)benzoic acid, or 4-(3-hydroxyphenyl)benzoic acid.

[0046] The aforementioned aromatic dihydroxy monomers are not limited to these, but may include, for example, 1,4-dihydroxybenzene, 1,3-dihydroxybenzene, 2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,6-naphthalenedicarboxylic acid, 1,6-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-dihydroxybiphenyl, or 4,4'-dihydroxybiphenyl ether.

[0047] The aforementioned aromatic dicarboxylic acid monomer is not limited to this, but may include, for example, terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, biphenyl-4,4'-dicarboxylic acid, or 4,4'-dicarboxydiphenyl ether.

[0048] The monomer of the aromatic diamine monomer is not limited to this, but may be, for example, 1,4-diaminobenzene, 1,3-diaminobenzene, 1,5-diaminonaphthalene, or 1,8-diaminonaphthalene.

[0049] The aforementioned aromatic hydroxyamine monomers are not limited to these, but may include, for example, 4-aminophenol, 3-aminophenol, 4-amino-1-naphthol, 5-amino-1-naphthol, 6-amino-2-naphthol, or 4-amino-4'-hydroxybiphenyl.

[0050] The aforementioned aromatic aminocarboxylic acid monomer is not limited to this, but may include, for example, 4-aminobenzoic acid, 3-aminobenzoic acid, or 6-amino-2-naphthoic acid.

[0051] In another example, the alkyl, alkoxy, or halogen-substituted aromatic hydroxycarboxylic acids, aromatic dihydroxys, aromatic dicarboxylic acids, aromatic diamines, aromatic hydroxyamines, aromatic and / or aminocarboxylic acid compounds, and ester-forming derivatives thereof such as acylation, can also be used as liquid crystal polymers.

[0052] In another example, a liquid crystal polymer may be used in which an aliphatic dihydroxy and / or aliphatic dicarboxylic acid compound is copolymerized with the aromatic hydroxycarboxylic acid, aromatic dihydroxy, aromatic dicarboxylic acid, aromatic diamine, aromatic hydroxyamine and / or aromatic aminocarboxylic acid compound, to the extent that it does not impede liquid crystallinity in the molten state of the resin.

[0053] In an unrestricted example, the thermoplastic liquid crystal polyester may be, for example, type I, composed of 4-hydroxybenzoic acid, terephthalic acid, and 4,4'-dihydroxybiphenyl; type II, composed of 4-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid; or type III, composed of 4-hydroxybenzoic acid, terephthalic acid, and ethylene glycol. Specifically, commercially available products currently on the market may also be included in the liquid crystal polymer, but as type I, products such as Sumitomo Chemical's Sumika Super and Solvay's Zyder can be used; as type II, Celanes' Vectra can be used; and as type III, products such as Unitika's Rodran or Mitsubishi Engineering Plastics' Novaculate can be used.

[0054] In one example, the insulating film may include at least two types of liquid crystal polymer resins. In this case, the liquid crystal polymer resins may include two types of liquid crystal polymer resins with different melting points. Specifically, the insulating film may include a high-melting-point liquid crystal polymer resin and a low-melting-point liquid crystal polymer resin.

[0055] While not particularly limited, the melting point temperature used to distinguish whether a liquid crystal polymer resin has a low or high melting point may be 270°C, 275°C, 280°C, 285°C, 290°C, 295°C, 300°C, 305°C, 310°C, 315°C, 320°C, 325°C, 330°C, 335°C, 340°C, 345°C, or 350°C.

[0056] In an unrestrictive example, the liquid crystal polymer resin may include a low-melting-point liquid crystal polymer resin with a melting point of 300°C or less, and a high-melting-point liquid crystal polymer resin with a melting point exceeding 300°C. In another unrestrictive example, the liquid crystal polymer resin may include a low-melting-point liquid crystal polymer resin with a melting point of 310°C or less, and a high-melting-point liquid crystal polymer resin with a melting point exceeding 310°C. In yet another unrestrictive example, the liquid crystal polymer resin may include a low-melting-point liquid crystal polymer resin with a melting point of 320°C or less, and a high-melting-point liquid crystal polymer resin with a melting point exceeding 320°C.

[0057] In other non-limiting examples, the melting points of the high-melting-point liquid crystal polymer resin and the low-melting-point liquid crystal polymer resin contained in the liquid crystal polymer resin may have a difference of at least 5°C, 10°C, 15°C, 20°C, 25°C, 300°C, 305°C, 310°C, 315°C, 320°C, 325°C, 330°C, 335°C, 340°C, 345°C, or 50°C or more (based on any one of 270°C, 275°C, 280°C, 285°C, 290°C, 295°C, 300°C, 305°C, 310°C, 315°C, 320°C, 325°C, 330°C, 335°C, 340°C, 345°C, and 350°C). For example, the liquid crystal polymer resin may include a low-melting-point resin with a melting point of 290°C or less and a high-melting-point resin with a melting point of 310°C or higher (a difference of 20°C in melting points). Alternatively, the liquid crystal polymer resin may include, for example, a low-melting-point resin with a melting point of 280°C or lower and a high-melting-point resin with a melting point of 320°C or higher (with a melting point difference of 40°C).

[0058] Low-melting-point liquid crystal polymer resins have low viscosity, which is advantageous for ensuring moldability and film-forming properties, but they are not sufficient for ensuring the heat resistance of the film. High-melting-point liquid crystal polymer resins, on the other hand, are not sufficient for ensuring moldability or film-forming properties, but they are advantageous for ensuring the heat resistance of the film. To ensure both film-forming properties and heat resistance, it is preferable to mix high-melting-point and low-melting-point liquid crystal polymer resins.

[0059] While not particularly limited, when the insulating film contains high-melting-point and low-melting-point liquid crystal polymer resins with different melting points as described above, exemplary high-melting-point liquid crystal polymer resins that can be used include Vectra C950 (Celanese) or LF-31 (ENEOS), and exemplary low-melting-point liquid crystal polymer resins that can be used include Vectra A950 (Celanese) or CX-2199 (ENEOS).

[0060] In one example, the insulating film may contain 1 to 15% by weight of polyarylate and 85 to 99% by weight of liquid crystal polymer resin. The liquid crystal polymer film may contain low-melting-point and high-melting-point liquid crystal polyester resins. Specifically, the insulating film may contain, for example, 2% or more by weight, 3% or more by weight, 4% or more by weight, 5% or more by weight, 6% or more by weight, 7% or more by weight, 8% or more by weight, 9% or more by weight, or 10% or more by weight of polyarylate. The upper limit of the polyarylate resin content in the insulating film may be, for example, 14% or less by weight, 13% or less by weight, 12% or less by weight, 11% or less by weight, 10% or less by weight, 9% or less by weight, 8% or less by weight, 7% or less by weight, 6% or less by weight, 5% or less by weight, 4% or less by weight, 3% or less by weight, or 2% or less by weight. In this case, the weight percentage is the content based on 100% by weight of the total content of the resin components forming the insulating film.

[0061] In one example, the insulating film may contain 15 to 60% by weight of a low-melting-point liquid crystal polymer resin (low-melting-point liquid crystal polyester resin). Specifically, the insulating film may contain 20% or more by weight, 25% or more by weight, 30% or more by weight, 35% or more by weight, 40% or more by weight, 45% or more by weight, 50% or more by weight, or 55% or more by weight of the low-melting-point liquid crystal polymer resin. The upper limit of the content of the low-melting-point liquid crystal polymer resin may be 55% or less by weight, 50% or less by weight, 45% or less by weight, 40% or less by weight, 35% or less by weight, 30% or less by weight, 25% or less by weight, or 20% or less by weight. In this case, the weight percentage is based on the total content of the resin components forming the insulating film, which is 100% by weight.

[0062] In one example, the insulating film may contain 15 to 80% by weight of a high-melting-point liquid crystal polymer resin (high-melting-point polyester resin). Specifically, the insulating film may contain 20% or more by weight, 25% or more by weight, 30% or more by weight, 35% or more by weight, 40% or more by weight, 45% or more by weight, 50% or more by weight, 55% or more by weight, 60% or more by weight, 65% or more by weight, 70% or more by weight, or 75% or more by weight of the high-melting-point liquid crystal polymer resin. The upper limit of the content of the high-melting-point liquid crystal polymer resin may be 75% or less by weight, 70% or less by weight, 65% or less by weight, 60% or less by weight, 55% or less by weight, 50% or less by weight, 45% or less by weight, 40% or less by weight, 35% or less by weight, 30% or less by weight, 25% or less by weight, or 20% or less by weight. In this case, the weight percentage is based on the total content of the resin components forming the insulating film, which is 100% by weight.

[0063] When this content range is satisfied, the surface hardness ratio and film viscosity according to the above relational formula are satisfied, thereby ensuring excellent film-forming properties, heat resistance, and adhesion.

[0064] An insulating film with such a configuration can have excellent heat resistance. For example, the insulating film can satisfy an elastic modulus of 150 MPa or more at 280°C. In this case, the elastic modulus refers to the elastic modulus at 280°C that is observed when the temperature is increased at a rate of 5°C / min under conditions of static strain of 0.15%, dynamic strain of 0.10%, and frequency of 1.0 Hz.

[0065] In one example of the invention, the insulating film can satisfy an elastic modulus of 150-600 MPa at 280°C, as confirmed when the temperature is increased at a rate of 5°C / min under conditions of static strain of 0.15%, dynamic strain of 0.10%, and frequency of 1.0 Hz.

[0066] Specifically, such elastic moduli are related to heat resistance. Due to the nature of the applications in which insulating films are used, they may be exposed to high temperatures or heat, and therefore must satisfy a specified elastic modulus.

[0067] For example, the lower limit of the elastic modulus may be 200 MPa or more, 250 MPa or more, 300 MPa or more, 350 MPa or more, 400 MPa or more, 450 MPa or more, 500 MPa or more, or 550 MPa or more. The upper limit may be, for example, 600 MPa or less, 550 MPa or less, 500 MPa or less, 450 MPa or less, 400 MPa or less, 350 MPa or less, 300 MPa or less, 250 MPa or less, or 200 MPa or less. In the specific example of this application, the insulating film can satisfy all of the surface roughness ratio, the film viscosity, and the elastic modulus according to the relational formula.

[0068] In one example, the insulating film can satisfy a dielectric constant (Dk) of less than 3.4. For example, the insulating film can satisfy a dielectric constant of 3.3 or less, 3.2 or less, 3.1 or less, or 3.0 or less. Satisfying this range is advantageous for reducing transmission loss. The dielectric constant can be measured using the apparatus described in the experiment described later.

[0069] In one example, the insulating film can satisfy a dielectric loss tangent (Df) of less than 0.005. For example, the insulating film can satisfy a dielectric loss tangent of 0.004 or less, 0.003 or less, 0.002 or less, or 0.001 or less. Satisfying this range is advantageous for reducing transmission loss. The dielectric loss tangent can be measured using the apparatus described in the experiment described later.

[0070] In one example, the insulating film can satisfy a peel force (or adhesive force) of 0.5 kN / m or more, measured while peeling off the copper foil from a test specimen in which a metal layer (e.g., copper foil), the insulating film, and the metal layer (e.g., copper foil) are sequentially laminated. Specifically, the peel force of the insulating film measured using such a test specimen may be 0.6 kN / m or more, 0.7 kN / m or more, 0.8 kN / m or more, or 0.9 kN / m or more. Such peel force or adhesive force measurements may be performed using a peel force evaluation tester (Chem Instrument, AR-1000), as described later.

[0071] The insulating film of this application can be used to manufacture FCCL (Flexible Copper Clad Laminate). For example, FCCL can be manufactured by laminating it together with a copper-containing metal layer. Specifically, FCCL can be manufactured by laminating a metal layer onto the insulating film and forming a circuit pattern, although etching (or etching) may be performed during the circuit pattern formation process.

[0072] In the manufacturing of FCCL, when laminating a metal layer onto an insulating film, a hot lamination process, which applies heat and pressure, can be used. The heat applied in this process melts the surface of the insulating film, and the molten resin moves in a flowable manner. At this time, the lower the viscosity of the insulating film and the more fluid it is, the more similar its shape to the surface of the metal layer becomes, and the contact area between the metal layer and the insulating film can be increased. The degree of this can be confirmed by the ratio of surface roughness in the relational formula described above. The improved adhesion between the metal layer and the insulating film, whose surface shapes are similar, can be confirmed through the experimental results described later.

[0073] In connection with the production of FCCL, known etching solutions, such as ferric chloride (FeCl3·6H2O, Iron(III) Chloride anhydrous), can be used to form circuit patterns on the metal layer. Although not particularly limited, the concentration of the ferric chloride solution used for etching (i.e., the weight percentage of ferric chloride excluding solvent in 100% by weight of the solution) may be 90% or more, 95% or more, and 100% or less.

[0074] In the manufacturing applications of FCCL, the metal layer that can be laminated with the insulating film of this application contains copper. The metal layer is what is commonly called copper foil, and may be, for example, rolled copper foil or electrolytic copper foil. Such a metal layer may contain, for example, 90% or more, 95% or more or 99% or more by weight of copper, and may contain small amounts of additives or impurities.

[0075] In other examples relating to this application, the application relates to a laminate comprising a metal layer and an insulating film. The laminate is, for example, FCCL or can be used to manufacture FCCL.

[0076] The laminate includes (A) a metal layer containing copper; and (B) an insulating film located on at least one surface of the metal layer. The laminate includes an insulating film that satisfies the following properties so that it can have not only excellent film-forming properties but also excellent adhesion between the metal layer and the insulating film.

[0077] In the specific example of this application, the insulating film included in the laminate satisfies a surface roughness ratio of 78% or more, calculated by the following relational formula.

[0078] [Relationship] Surface roughness ratio (%) = (S r2 / S r1 ) × 100 In the above relation, S r1 This can mean the arithmetic mean roughness of any one surface of the metal layer that forms the FCCL together with the insulating film. In this case, S r1 The one surface of the metal layer on which the roughness is measured can mean, for example, one surface of the metal layer that faces or is in contact with the insulating film in a laminate such as FCCL. During the manufacture of FCCL, one surface of the metal layer (e.g., copper foil) laminated with the insulating film generally has an arithmetic mean roughness (S) of 0.1 μm or more, 0.2 μm or more, 0.3 μm or more, 0.4 μm or more, or 0.5 μm or more, and 0.6 μm or less, 0.5 μm or less, 0.4 μm or less, 0.3 μm or less, or 0.2 μm or less. r1 ) can have.

[0079] In the above relation, S r2 This can mean the arithmetic mean roughness of any one surface of the insulating film. In this case, S r2Any one surface of the insulating film on which the measurement is taken can mean, for example, one surface of the insulating film that faces or is in contact with the metal layer (e.g., copper foil) in a laminate such as FCCL. According to a specific example of this application, the S r2 This can be measured after immersing the insulating film or a laminate such as FCCL (formed by laminating an insulating film with a metal layer (copper foil)) in a ferric chloride (FeCl3·6H2O, Iron(III) Chloride anhydrous) solution for up to one hour and washing it. The concentration of the ferric chloride solution (i.e., the weight percentage of ferric chloride excluding the solvent in 100% by weight of the solution) is 90% or more, 95% or more, and may be 100% or less, although it is not particularly limited.

[0080] In one example, such arithmetic mean roughness may be measured using an 800 μm cutoff. Such arithmetic mean roughness can be measured using known instruments, such as an optical surface roughness meter (3D profiler), though this is not particularly limited.

[0081] The technical significance and specific numerical values ​​regarding the surface roughness ratio have been explained above, so they will be omitted here.

[0082] In one example, the insulating film comprises a liquid crystal polymer and a polyarylate, and more preferably, two liquid crystal polymers with different melting points and a polyarylate. Furthermore, an insulating film satisfying these characteristics can have a film viscosity of 1,000 poise or less. Such viscosity satisfies the surface roughness ratio described above and prevents a decrease in the adhesive strength of the insulating film to the copper foil. It also allows for a higher adhesive strength than that expected when using polyarylate as a component of an insulating film in the prior art. The specific viscosity values ​​of the insulating film are as described above.

[0083] In one example, the insulating film satisfies the requirement that its elastic modulus at 280°C be 150 MPa or higher. In this case, the elastic modulus refers to the elastic modulus at 280°C observed when the temperature is increased at a rate of 5°C / min under conditions of static strain 0.15%, dynamic strain 0.10%, and frequency 1.0 Hz. The technical significance and specific numerical values ​​of the elastic modulus have been explained above, so they will be omitted here.

[0084] In one example, the metal layer of the laminate may be a patterned metal layer. Specifically, a metal layer having a predetermined pattern can be formed on a laminate in which a metal layer and an insulating film are laminated, while a portion of the metal layer is removed by an etching process.

[0085] In addition to the above-mentioned details relating to the laminate of this application, the explanation of the components included in the laminate and their manufacturing process is as described above and will therefore be omitted here.

[0086] The applications of such laminates are not particularly limited, but for example, the laminate is suitable for FCCL (Flexible Copper Clad Laminate), a component for fifth-generation mobile communications. [Effects of the Invention]

[0087] According to this application, an insulating film is provided that not only has excellent adhesion to a metal layer laminated together with it, but also has excellent heat resistance and film-forming properties; and a laminate containing the same. [Modes for carrying out the invention]

[0088] The function and effects of the invention will be explained in more detail below through specific embodiments of the invention. However, these are presented as examples of the invention and do not limit the scope of the invention's rights in any way.

[0089] Manufacturing of liquid crystal films (or insulating films) Example 1 A thermoplastic liquid crystal polyester pellet 1 (Vectra C950 from Celanese) was used as a high-melting-point liquid crystal polymer resin, and liquid crystal polyester pellet 2 (Vectra A950 from Unitika) and polyarylate pellet 3 (U-Polymer U-100) were used as low-melting-point liquid crystal polymer resins. After mixing these, a mixed pellet containing the above components was produced using a twin-screw extruder (extruder temperature approximately 320°C).

[0090] The mixed pellets of Example 1 were prepared by mixing each component in predetermined amounts to satisfy the film viscosity and elastic modulus of this application. In the production of the mixed pellets of Example 1, 79 wt% of liquid crystal polyester pellet 1 (Vectra C950), 20 wt% of liquid crystal polyester pellet 2 (Vectra A950), and 1 wt% of polyarylate pellet 3 (U-100) were used (see Table 1 below).

[0091] The mixed pellets manufactured as described above were fed into a single-screw extruder (Labotec, LE30-30 / CV) to produce a 50 μm thick film. At this time, the L / D ratio of the extruder was 30, and the diameter was 30 mm. A T-die was used, with a die slit spacing of 0.5 mm and a slit width of 300 mm. The extruder temperature was set to 380°C, the die temperature to 350°C, and the screw speed inside the extruder was set to 65 rpm.

[0092] Examples 2-12 A 50 μm thick film was prepared using the same thermoplastic liquid crystal polyester pellets and polyarylate pellets as in Example 1, but with only the content (amount added) of each component differing as shown in Tables 1 and 2 below. Similar to Example 1, the mixed pellets were prepared with each component in predetermined amounts to satisfy the film viscosity of this application (see Tables 1-2 below).

[0093] Comparative Example 1 Thermoplastic liquid crystal polyester pellet 1 (Vectra C950 from Celanese) and polyarylate pellet 3 (U-Polymer U-100) were mixed, and then a mixed pellet containing the above components was produced using a twin-screw extruder (extruder temperature approximately 320°C).

[0094] The mixed pellets of Comparative Example 1 were prepared by mixing each component in predetermined amounts at a level that did not satisfy the film viscosity and / or elastic modulus of this application. In the production of the mixed pellets of Comparative Example 1, 99 wt% of liquid crystal polyester pellet 1 (Vectra C950) and 1 wt% of polyarylate pellet 3 (U-100) were used (see Table 3 below).

[0095] The mixed pellets of Comparative Example 1 were fed into a single-screw extruder (Labotec, LE30-30 / CV) to produce a film with a thickness of 50 μm. The film manufacturing conditions were the same as those described in Example 1.

[0096] Comparative Examples 2-5 The thermoplastic liquid crystal polyester pellets and polyarylate pellets were adjusted to the content (amount added) shown in Table 3 below to produce mixed pellets for each comparative example. Similar to Comparative Example 1, the mixed pellets were prepared by mixing each component in predetermined amounts at a level that did not satisfy the film viscosity and / or elastic modulus of this application (see Table 3 below).

[0097] Then, the mixed pellets of each comparative example were fed into a single-screw extruder (Labotec, LE30-30 / CV) to produce a film with a thickness of 50 μm. At this time, the film manufacturing conditions were the same as those described in Example 1.

[0098] Film characterization For the films of the examples and comparative examples, the viscosity of the film, dielectric constant, dielectric loss tangent, adhesive strength, heat resistance, surface roughness of the copper foil before etching, and surface roughness of the film surface after etching were confirmed and recorded in Tables 1 to 3. The evaluation items and methods are as follows.

[0099] * Dielectric constant and dielectric loss tangent (unitless) The dielectric constant and dielectric loss tangent of the films in the examples and comparative examples were measured using a Microwave Molecular Orientation Analyzer (MOA-7015, manufactured by Oji Instruments Co., Ltd.). The frequency applied during measurement was 15 GHz.

[0100] *Film viscosity (poise) The melt viscosity of the films for each example and comparative example was determined at 320°C using a capillary rheometer (capillary viscometer). The capillary rheometer had a nozzle 20 mm long and 1 mm in diameter, with a piston diameter of 12 mm, and the melt viscosity was determined at a shear rate of 500 rpm.

[0101] *Surface roughness before and after etching (μm) 1) Copper foil etching (etching): A copper foil with a thickness of 12 μm (JX Metals Corporation, JXEFL-V2) was prepared, and a copper foil / (each example or comparative example) film / copper foil laminate was manufactured for adhesion strength evaluation. The laminate was then cut into 10 mm x 20 mm sections, immersed in a ferric chloride (FeCl3·6H2O, Iron(III) Chloride anhydrous) solution (approximately 97% concentration) for 30 minutes, and then washed with running water.

[0102] 2) Surface roughness of the copper foil before etching and the surface roughness of the film surface after etching: The arithmetic mean roughness of the surface was measured using a 3D Optical Profiler (NPFLEX, manufactured by Bruker). Specifically, the microscope magnification was set to 50x in Vertical Scanning Interferometry (VSI) mode, and a surface image with a size of 95 μm vertically and 126 μm horizontally was measured. Then, the arithmetic mean roughness of the surface was determined at a cut-off of 800 μm. In other words, surface roughness is measured for irregularities with wavelengths less than or equal to the aforementioned cut-off value. For reference, the surface roughness of the film surface after etching refers to the surface roughness of the film surface where the copper foil was located before etching, but from which the copper has been removed by the etching process.

[0103] *Adhesive force (kN / m) A liquid crystal polymer film was inserted between two copper foils, and a laminate was formed using a hot press. The adhesive strength was then determined by the force generated while peeling off the copper foils.

[0104] After cutting the film to 50mm x 150mm, it was inserted between two 12μm copper foils (JX Metals Corporation, JXEFL-V2) and laminated using a hot press. The press pressure during hot pressing was 20MPa and the hot pressing temperature was 300°C.

[0105] The prepared copper foil / film / copper foil laminate was cut into 25 mm x 150 mm sections to create evaluation test pieces. The peel force generated while peeling the copper foil was then expressed as adhesive force using a peel force evaluation tester (Chem Instrument, AR-1000).

[0106] * Elastic modulus (heat resistance) (MPa) The elastic modulus (E') at 280°C was evaluated for the films produced in the examples and comparative examples using a dynamic mechanical analyzer (DMA, NETZSCH DMA GABO EPLEXOR 100N). The elastic modulus at 280°C was evaluated while increasing the temperature at a rate of 5°C / min with a static strain of 0.15%, a dynamic strain of 0.10%, and a frequency of 1.0 Hz. If the evaluation sample fractured during the evaluation, making measurement of the elastic modulus difficult, it was noted as "measurement impossible."

[0107] [Table 1]

[0108] [Table 2]

[0109] [Table 3]

[0110] Through the results in Tables 1-3 above, it can be confirmed that even when polyallyrate resin is included, Examples 1-12, which use two or more liquid crystal polymer resins with different melting points together, exhibit an optimal film viscosity that suppresses the increase in viscosity of the resin composition and ensures excellent coating properties compared to Comparative Examples 1-5, and that the adhesion to copper foil is improved.

[0111] Furthermore, Examples 1 to 12 satisfied the range of 150 to 600 MPa for the elastic modulus at 280°C measured under the conditions described above.

[0112] In contrast, Comparative Examples 1 to 5 either used a single low-melting-point or high-melting-point liquid crystal polymer, or even when these were mixed, they could not satisfy the scope of the present application. As a result, the viscosity of the film increased, leading to poor adhesion to the copper foil, or the elastic modulus exceeded 600 MPa, or the elastic modulus could not be measured. Therefore, since the elastic modulus is related to heat resistance, Comparative Examples 1 to 5 may have poor heat resistance.

Claims

1. An insulating film for laminating with a copper-containing metal layer to form FCCL (Flexible Copper Clad Laminate), The surface roughness ratio calculated by the following relational formula satisfies 78% or more. The insulating film is formed from a resin composition containing two or more liquid crystal polymers having different polyarylates and melting points. The two or more liquid crystal polymers described above, based on a total content of 100% by weight of the resin components forming the insulating film, include 15 to 60% by weight of a low-melting-point liquid crystal polymer resin with a melting point of 300°C or less and 15 to 80% by weight of a high-melting-point liquid crystal polymer resin with a melting point exceeding 300°C, in an insulating film: [Relational expression] Surface roughness ratio (%) = (S r2 / S r1 ) × 100 (In the above relational expression, S r1 This is the arithmetic mean roughness of any one surface of the metal layer that forms FCCL together with the insulating film, and is in the range of 0.1 to 0.6 μm. S r2 This is the arithmetic mean roughness of any one surface of the insulating film, wherein the insulating film or the FCCL is ferric chloride (FeCl ３ 6H 2 The measurements were taken after immersion and washing in an Iron(III) Chloride anhydrous solution for one hour. The aforementioned arithmetic mean roughness was measured using 800 μm as the cutoff standard.

2. The insulating film is the insulating film according to claim 1, having a film viscosity of 1,000 poise or less (provided that the film viscosity is measured at 320°C and a shear rate of 500 / sec).

3. An insulating film according to claim 1, having a film viscosity of 300 to 1000 poise or less (provided that the film viscosity is measured at 320°C and a shear rate of 500 / sec).

4. The insulating film according to claim 1, wherein the insulating film satisfies an elastic modulus of 150 to 600 MPa at 280°C, as confirmed when the temperature is increased at a rate of 5°C / min under conditions of static strain of 0.15%, dynamic strain of 0.10%, and frequency of 1.0 Hz.

5. (A) A metal layer containing copper; and (B) A laminate comprising an insulating film located on at least one surface of the metal layer, The insulating film satisfies a surface roughness ratio of 78% or more, calculated by the following relational formula. The insulating film is formed from a resin composition containing two or more liquid crystal polymers having different polyarylates and melting points. The laminate comprises, based on 100% by weight of the total resin components forming the insulating film, 15 to 60% by weight of a low-melting-point liquid crystal polymer resin with a melting point of 300°C or less and 15 to 80% by weight of a high-melting-point liquid crystal polymer resin with a melting point exceeding 300°C: [Relational expression] Surface roughness ratio (%) = (S r2 / S r1 ) × 100 (In the above relational expression, S r1 is the arithmetic mean roughness of one surface of the metal layer facing or contacting the insulating film, and is in the range of 0.1 to 0.6 μm. S r2 This is the arithmetic mean roughness of one surface of the insulating film that faces or is in contact with the metal layer, wherein the laminate is made of ferric chloride (FeCl ３ 6H 2 The measurements were taken after immersion and washing in an Iron(III) Chloride anhydrous solution for one hour. The aforementioned arithmetic mean roughness was measured using 800 μm as the cutoff standard.

6. The insulating film is the laminate according to claim 5, having a film viscosity of 1000 poise or less (provided that the film viscosity is measured at 320°C and a shear rate of 500 / sec).

7. The insulating film has a film viscosity of 300 to 1000 poise or less, as described in claim 6 (wherein the film viscosity is measured at 320°C and a shear rate of 500 / sec).

8. The laminate according to claim 5, wherein the insulating film satisfies an elastic modulus of 150 to 600 MPa at 280°C, as confirmed when the temperature is increased at a rate of 5°C / min under conditions of static strain of 0.15%, dynamic strain of 0.10%, and frequency of 1.0 Hz.

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