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 to related applications This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0106433 filed on August 24, 2022, and Korean Patent Application No. 10-2023-0103406 filed on August 8, 2023, and all the contents disclosed in the documents of the Korean patent applications are incorporated herein by reference.

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

Background Art

[0003] 5G, which refers to the 5th Generation mobile communication, is a core infrastructure of the Fourth Industrial Revolution that transmits huge amounts of data at ultra-high speeds and connects (hyper-connects) everything in real time (ultra-low latency), compared to the existing 4th Generation mobile communication, LTE (Long-Term Evolution). The biggest challenge of such 5G mobile communication technology is to reduce transmission loss. 5G uses a high-frequency band (short-wavelength band) with high directivity, but in this case, the ratio of radio waves absorbed by substances during movement (transmission loss ratio) is high. Therefore, components such as semiconductors and PCBs (Printed Circuit Boards) for 5G mobile communication require a low dielectric constant characteristic that can reduce transmission loss. To ensure the low dielectric constant characteristic, insulators using liquid crystal polymer resins have been mainly studied.

[0004] On the other hand, in addition to the low dielectric characteristics mentioned above, although liquid crystal polymer films have various strengths such as high strength, high heat resistance, and low water absorption rate, there is a problem that the commercialization of the film is not easy. This is due to the characteristics of the liquid crystal polymer resin. Specifically, since the liquid crystal polymer resin forms a liquid crystal structure in a molten state and has high orientation characteristics in the flow direction, when manufacturing the film, the film breaks in the discharge direction from the die, and it is difficult to ensure film formability such as poor dimensional stability (dimensional non-uniformity).

[0005] In order to improve the disadvantages of the above-mentioned liquid crystal polymer film, in Japanese Registered Patent No. 4091209, an attempt was made to apply polyarylate, which is an amorphous (or non-crystalline) polymer, to improve the heat insulation strength of the film and the left-right vibration (film-forming property) of bubbles. Also, in Japanese Registered Patent No. 3896324, attempts have been made to apply thermoplastic resins (PEI, PES, PPS, and polyarylate) to improve dimensional stability. Thus, the conventional attempts as described in the above patent documents focus on improving the film-forming property of the liquid crystal polymer film.

[0006] However, when applying the amorphous polymers or thermoplastic resins mentioned in the above patent documents, such as resins containing polyarylate, the adhesive strength decreases due to an increase in the melt viscosity, so adhesion failure may occur 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 required.

Summary of the Invention

Problems to be Solved by the Invention

[0007] One object of the present application is to solve the problems of the above-mentioned prior art.

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

[0009] The above objects and other objects of the present application can all be solved by the invention of the present application described in detail below.

Means for Solving the Problems

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

[0011] [Relational Expression] Ratio of surface roughness (%) = (S r2 / S r1 ) × 100 (In the above relational expression, S r1 is the arithmetic mean roughness of any one surface of the metal layer that forms the FCCL together with the insulating film, and is in the range of 0.1 to 0.6 μm, S r2 is the arithmetic mean roughness of any one surface of the insulating film, and is measured after immersing and washing the insulating film or the FCCL in an iron(III) chloride (FeCl3·6H2O, Iron(III) Chloride anhydrous) solution within 1 hour, The arithmetic mean roughness is measured with a cut-off criterion of 800 μm.)

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

[0013] Hereinafter, the insulating film and the laminate including the same according to an embodiment of the invention will be described in more detail.

[0014] Unless otherwise explicitly mentioned in this specification, the technical terms are only for referring to specific embodiments and are not intended to limit the present invention.

[0015] As used in this specification, the singular forms also include the plural forms unless the context clearly indicates the contrary meaning.

[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 said idea and technical scope are included.

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

[0019] In connection with this, the inventors of the present application have confirmed that a liquid crystal polymer film manufactured by applying a polyarylate resin is effective to a certain extent in improving the film-forming property of the liquid crystal polymer film, but the adhesion between the liquid crystal polymer film and the copper foil is low. Specifically, the inventors of the present application have found that the conventional method for manufacturing 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 causing insufficient adhesion between the copper foil and the insulating film, and thus have completed the invention of the present application to solve such problems.

[0020] Therefore, according to one embodiment of the invention, there is provided an insulating film for forming a Flexible Copper Clad Laminate (FCCL) by being laminated together with a metal layer containing copper, and 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 is the arithmetic mean roughness of either one surface of the metal layer that forms the FCCL together with the insulating film, and is in the range of 0.1 to 0.6 μm, S r2 is the arithmetic mean roughness of either one surface of the insulating film, and is measured after immersing and washing the insulating film or the FCCL in an iron(III) chloride (FeCl3·6H2O, Iron(III) Chloride anhydrous) solution within 1 hour, The arithmetic mean roughness is measured with a cut-off criterion of 800 μm.)

[0022] In a specific example according to the present application, the present application relates to an insulating film.

[0023] The present application uses a resin composition containing a polyarylate resin and at least two kinds of liquid crystal polyesters, and by adjusting the mixing ratio thereof, it is possible to suppress an increase in the viscosity of the resin composition and improve the adhesive force with a copper foil. In one embodiment, the two or more kinds of liquid crystal polyesters can include low melting point and high melting point liquid crystal polyester resins having different melting points from each other. Therefore, the present application can provide an insulating film for forming an FCCL (Flexible Copper Clad Laminate) excellent in the ratio of surface roughness and a laminate including the same.

[0024] That is, the insulating film can be used for applications for forming an FCCL (Flexible Copper Clad Laminate) by being laminated together with a metal layer containing copper, and can have characteristics suitable for such applications (for example, characteristics capable of solving the problems of the above-described prior art). Specifically, the insulating film can satisfy the surface roughness described below and is formed from the components described below.

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

[0026] [Relational Expression] Surface roughness ratio (%) = (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 the FCCL, the surface of the metal layer that faces or contacts the insulating film. When manufacturing the 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 the FCCL, the 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 (i.e., the weight percentage of iron(III) chloride excluding the solvent in 100% by weight of the solution) can be 90% or more, 95% or more, and 100% or less.

[0029] In a specific example of the present application, such arithmetic mean roughness may be measured with a cut-off criterion of 800 μm. And, without particular limitation, such arithmetic mean roughness can be measured using a known device such as an optical surface roughness meter (3D Profiler).

[0030] Related to the problems of the prior art described above, for example, the decrease in adhesive force due to the increase in the melt viscosity of the insulating film, the inventor of the present application experimentally confirmed that when the surface roughness of the insulating film is designed to be similar to the surface roughness of the metal layer (e.g., copper foil), the decrease in adhesive force can be prevented. Specifically, as confirmed from the following experiment, when the adhesive force between the metal layer (e.g., copper foil) forming the FCCL 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 (after etching or after etching) can follow the surface roughness of the copper foil before etching to a certain extent or more. Such a design includes, for example, controlling the viscosity (melt viscosity) of the insulating film to 1,000 poise or less as described below.

[0031] In one example, the lower limit of the ratio of the surface roughness calculated by the relational expression 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. And 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 can have a film viscosity of 1,000 poise or less. In another example, the insulating film can have a film viscosity of 300 to 1,000 poise or less (wherein the film viscosity is measured at 320 °C and a shear rate of 500 / sec). Such a viscosity satisfies the ratio of surface roughness calculated by the above relational expression and can prevent a decrease in the adhesive force of the insulating film to the copper foil. Further, such a viscosity enables an adhesive force higher than the adhesive force level expected when polyarylate is used as one component of the insulating film in the prior art to be obtained.

[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. And its 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 can be formed or manufactured so as to satisfy at least the above-described ratio of surface roughness and / or film viscosity.

[0035] In connection with this, according to a specific example of the present application, the insulating film can include polyarylate and liquid crystal polymer resin. More specifically, the insulating film can be produced from a composition containing polyarylate and liquid crystal polymer resin. Even more specifically, the insulating film can be produced from a composition containing polyarylate and two or more kinds of liquid crystal polymer resins (more preferably, two or more kinds of liquid crystal polyester resins having different melting points from each other).

[0036] For example, the insulating film can be formed by melt-molding a composition containing an insulating film-forming component. Specifically, a composition containing polyarylate and liquid crystal polymer resin is melt-kneaded with an extruder, and through the process of discharging the molten resin through the slit of a die, the insulating film can be obtained. A T-die or a circular die may be used in such a process.

[0037] In some cases, stretching of the extruded insulating film may be performed. As stretching methods, known techniques such as uniaxial stretching or biaxial stretching, inflation or laminate lamination stretching can be considered.

[0038] According to still another example, an insulating film laminate may be formed by joining a different thermoplastic polymer film at the same time as forming the insulating film with a die slit. At this time, as the different thermoplastic polymers that can be used, polyolefins such as polyethylene, polypropylene, and ethylene-α-olefin copolymer; or polyesters such as polystyrene, polycarbonate, polyethylene terephthalate, and polybutylene terephthalate can be used. In addition, polyacetal, polyamide, polyphenylene ether, polyethersulfone, ethylene-vinyl acetate copolymer, polyvinyl chloride, polyvinylidene chloride, polyphenylene sulfide, fluororesin, etc. can also be used.

[0039] The polyarylate used for forming the insulating film is an aromatic polyester produced by polycondensing an aromatic dicarboxylic acid and an aromatic diol. As long as there is no problem in satisfying the film viscosity, elastic modulus and / or relational expression described above, the specific structure is not particularly limited. The polyarylate functions advantageously to improve the moldability or film-forming property of the insulating film.

[0040] <U+ On the other hand, as described above, in order to improve the film-forming property of the insulating film, a polyarylate component which is an amorphous polymer can be used. However, a polyarylate having a high level of viscosity shows poor fluidity in the process of adhering the insulating film and the metal layer (e.g., copper foil) by thermal adhesion, whereby the resin cannot sufficiently penetrate the surface of the copper foil, which may result in a decrease in the adhesive force between the insulating film and the metal layer. Therefore, it is preferable to select a liquid crystal polymer resin so as to prevent a decrease in the adhesive force generated by using the polyarylate resin.

[0041] The liquid crystal resin or liquid crystal polymer used for forming the insulating film means a polymer which maintains a crystalline state in a molten state and has liquid crystallinity. As long as there is no problem in satisfying the surface viscosity ratio and / or film viscosity of the relational expression described above, the chemical composition and structure of the liquid crystal polymer are not particularly limited.

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

[0043] Alternatively, the liquid crystal polymer can contain one or more polymers in which an isocyanate-derived bond such as an imide bond, a carbonate bond, a carbodiimide bond or an isocyanurate bond is additionally introduced into an aromatic polyester or an aromatic polyester amide.

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

[0045] The aromatic hydroxycarboxylic acid monomer is not limited thereto, and for example, it may be 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, etc.

[0046] The aromatic dihydroxy monomer is not limited thereto, and for example, it may be 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, etc.

[0047] The aromatic dicarboxylic acid monomer is not limited thereto, and for example, it may be terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, biphenyl-4,4'-dicarboxylic acid or 4,4'-dicarboxydiphenyl ether, etc.

[0048] The monomer of the aromatic diamine monomer is not limited thereto, and for example, it may be 1,4-diaminobenzene, 1,3-diaminobenzene, 1,5-diaminonaphthalene or 1,8-diaminonaphthalene, etc.

[0049] The aromatic hydroxyamine monomer is not limited thereto, and for example, it may be 4-aminophenol, 3-aminophenol, 4-amino-1-naphthol, 5-amino-1-naphthol, 6-amino-2-naphthol, 4-amino-4'-hydroxybiphenyl, or the like.

[0050] The aromatic aminocarboxylic acid monomer is not limited thereto, and for example, it may be 4-aminobenzoic acid, 3-aminobenzoic acid, 6-amino-2-naphthoic acid, or the like.

[0051] In another example, alkyl, alkoxy, or halogen substituents of the aromatic hydroxycarboxylic acid, aromatic dihydroxy, aromatic dicarboxylic acid, aromatic diamine, aromatic hydroxyamine, aromatic and / or aminocarboxylic acid compounds, and ester-forming derivatives such as acylation thereof can also be used as the liquid crystal polymer.

[0052] In another example, a liquid crystal polymer obtained by copolymerizing an aliphatic dihydroxy and / or aliphatic dicarboxylic acid compound with the aromatic hydroxycarboxylic acid, aromatic dihydroxy, aromatic dicarboxylic acid, aromatic diamine, aromatic hydroxyamine, and / or aromatic aminocarboxylic acid compound may be used as long as it does not inhibit the liquid crystallinity in the resin molten state.

[0053] In a non-limiting 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, currently commercially available products may also be included in the liquid crystal polymer. For type I, Sumitomo Chemical's Sumika Super, Solvay's Xydar can be used; for type II, Celanese's Vectra can be used; for type III, Unitika's Rodrun or Mitsubishi Engineering Plastics' Novaculite can be used.

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

[0055] Although not particularly limited, the melting point temperature for distinguishing the presence or absence of a low melting point or a high melting point of the liquid crystal polymer resin 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 non-limiting specific examples, the liquid crystal polymer resin can include a low melting point liquid crystal polymer resin having a melting point of 300°C or lower and a high melting point liquid crystal polymer resin having a melting point exceeding 300°C. In other non-limiting examples, the liquid crystal polymer resin can include a low melting point liquid crystal polymer resin having a melting point of 310°C or lower and a high melting point liquid crystal polymer resin having a melting point exceeding 310°C. In still other non-limiting examples, the liquid crystal polymer resin can include a low melting point liquid crystal polymer resin having a melting point of 320°C or lower and a high melting point liquid crystal polymer resin having a melting point exceeding 320°C.

[0057] In still 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 can have a difference of at least 5°C or more, 10°C or more, 15°C or more, 20°C or more, 25°C or more, 30°C or more, 35°C or more, 40°C or more, 45°C or more, 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 can include a low-melting-point resin with a melting point of 290°C or lower and a high-melting-point resin with a melting point of 310°C or higher (the difference in melting point is 20°C). Alternatively, the liquid crystal polymer resin can 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 (the difference in melting point is 40°C).

[0058] In the case of the low-melting-point liquid crystal polymer resin, the viscosity is low, which is advantageous for ensuring moldability or film-forming properties, but it is not sufficient for ensuring the heat resistance of the film. And in the case of the high-melting-point liquid crystal polymer resin, it is not sufficient for ensuring moldability or film-forming properties, but it is advantageous for ensuring the heat resistance of the film. In order to ensure all of the film-forming properties and heat resistance, it is preferable that the high-melting-point liquid crystal polymer resin and the low-melting-point liquid crystal polymer resin are mixed.

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

[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% by weight or more, 3% by weight or more, 4% by weight or more, 5% by weight or more, 6% by weight or more, 7% by weight or more, 8% by weight or more, 9% by weight or more, or 10% by weight or more of polyarylate. And the upper limit of the content of the polyarylate resin in the insulating film may be, for example, 14% by weight or less, 13% by weight or less, 12% by weight or less, 11% by weight or less, 10% by weight or less, 9% by weight or less, 8% by weight or less, 7% by weight or less, 6% by weight or less, 5% by weight or less, 4% by weight or less, 3% by weight or less, or 2% by weight or less. At this time, the % by weight 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% by weight or more, 25% by weight or more, 30% by weight or more, 35% by weight or more, 40% by weight or more, 45% by weight or more, 50% by weight or more, or 55% by weight or more of the low melting point liquid crystal polymer resin. And the upper limit of the content of the low melting point liquid crystal polymer resin may be 55% by weight or less, 50% by weight or less, 45% by weight or less, 40% by weight or less, 35% by weight or less, 30% by weight or less, 25% by weight or less, or 20% by weight or less. At this time, the % by weight is the content based on 100% by weight of the total content of the resin components forming the insulating film.

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

[0063] When the content range is satisfied, the surface hardness ratio and film viscosity according to the relational expression are satisfied, thereby ensuring excellent film formability, heat resistance, and adhesiveness.

[0064] The insulating film having 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. At this time, the elastic modulus means the elastic modulus at 280°C confirmed when the temperature is increased at a rate of 5°C / min under the conditions of a static strain of 0.15%, a dynamic strain of 0.10%, and a frequency of 1.0 Hz.

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

[0066] Specifically, such an elastic modulus is related to heat resistance. Due to the characteristics of the application where the insulating film is used, it may be exposed to high temperature or heat, so a predetermined elastic modulus must be satisfied.

[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. And 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 a specific example of the present application, the insulating film can satisfy all of the surface roughness ratio according to the relational expression, the film viscosity, and the elastic modulus.

[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. When satisfying this range, it is advantageous for reducing transmission loss. The dielectric constant can be measured using the apparatus described in the experiments described later.

[0069] In one example, the insulating film can satisfy a dielectric tangent (Df) of less than 0.005. For example, the insulating film can satisfy a dielectric tangent of 0.004 or less, 0.003 or less, 0.002 or less, or 0.001 or less. When satisfying this range, it is advantageous for reducing transmission loss. The dielectric tangent can be measured using the apparatus described in the experiments 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 the copper foil from a test piece in which a metal layer (e.g., copper foil), an insulating film, and a metal layer (e.g., copper foil) are sequentially laminated. Specifically, the peel force of the insulating film measured using such a test piece 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. Measurement of such a peel force or adhesive force may be performed using a peel force evaluation tester (Chem Instrument Co., AR-1000) as described later.

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

[0072] When manufacturing FCCL and laminating a metal layer on the insulating film, the hot lamination process with heat and pressure applied is applicable. The heat applied in the process melts the surface of the insulating film, and the molten resin moves with fluidity. At this time, the viscosity of the insulating film may be low enough to flow and be similar to the shape of the surface of the metal layer, and the contact area between the metal layer and the insulating film can be increased. The degree can be confirmed by the ratio of the surface roughness in the above-mentioned relational expression. The improved adhesive force between the metal layer and the insulating film with similar surface shapes can be confirmed through the experimental results described later.

[0073] When manufacturing FCCL and forming a circuit pattern on the metal layer, known etching solutions such as ferric chloride (FeCl3·6H2O, Iron(III) Chloride anhydrous) can be used. Although not particularly limited, the concentration of the ferric chloride solution used for etching (that is, the weight percentage of ferric chloride excluding the solvent in 100% by weight of the solution) can be 90% or more, 95% or more, and may be 100% or less.

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

[0075] In another example according to the present application, the present application relates to a laminate including a metal layer and an insulating film. The laminate can be, for example, an FCCL or can be used in the manufacture of an 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 characteristics so as to have not only excellent film-forming properties but also excellent adhesive strength between the metal layer and the insulating film.

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

[0078] [Relational Expression] Surface roughness ratio (%) = (S r2 / S r1 ) × 100 In the above relational expression, S r1 can mean the arithmetic mean roughness of any one surface of the metal layer that forms an 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, in a laminate such as an FCCL, one surface of the metal layer that faces or contacts the insulating film. During the manufacture of an FCCL, any one surface of the metal layer (e.g., 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.

[0079] In the above relational expression, S r2 can mean the arithmetic mean roughness of any one surface of the insulating film. At this time, the S r2Either side of the insulating film to be measured can, for example, in a laminate such as an FCCL, mean the side 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 a laminate such as an FCCL (formed by laminating an insulating film and a metal layer (copper foil)) 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 (i.e., the weight percentage of iron(III) chloride excluding the solvent in 100% by weight of the solution) may be 90% or more, or 95% or more, and may be 100% or less.

[0080] In one example, such an arithmetic mean roughness can be measured with a cut-off criterion of 800 μm. And although not particularly limited, such an arithmetic mean roughness can be measured using a known device such as an optical surface roughness meter (3D Profiler).

[0081] Since the technical significance and specific numerical values regarding the ratio of surface roughness have been described as above, this description is omitted.

[0082] In one example, the insulating film contains a liquid crystal polymer and a polyarylate, and more preferably, can contain two liquid crystal polymers having different melting points and a polyarylate. Further, an insulating film satisfying such characteristics can have a film viscosity of 1,000 poise or less. Such a viscosity satisfies the above-described ratio of surface roughness and can prevent a decrease in the adhesive force of the insulating film to the copper foil. Also, an adhesive force higher than the adhesive force level expected when using a polyarylate as one component of the insulating film in the prior art can be obtained. The specific viscosity value of the insulating film is as described above.

[0083] In one example, the insulating film satisfies an elastic modulus of 150 MPa or more at 280°C. At this time, the elastic modulus means the elastic modulus at 280°C confirmed when the temperature is raised at a rate of 5°C / min under the conditions of a static strain of 0.15%, a dynamic strain of 0.10%, and a frequency of 1.0 Hz. Since the technical significance and specific numerical values related to the elastic modulus have been described as above, this description is omitted.

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

[0085] In addition to the content described above in relation to the laminate of the present application, the description of the configuration included in the laminate and its manufacturing, etc. is as described above, so this is omitted.

[0086] The use of such a laminate is not particularly limited. For example, the laminate is suitable for an FCCL (Flexible Copper Clad Laminate) which is a component for fifth-generation mobile communication.

Advantages of the Invention

[0087] According to the present application, there are provided an insulating film excellent not only in adhesion to a metal layer to be laminated together but also in heat resistance and film-forming properties; and a laminate including the same.

Embodiments for Carrying Out the Invention

[0088] Hereinafter, the actions and effects of the invention will be described more specifically through specific examples of the invention. However, this is presented as an example of the invention, and the scope of rights of the invention is not limited in any way by this.

[0089] Manufacture of liquid crystal film (or insulating film) Example 1 As the high melting point liquid crystal polymer resin, thermoplastic liquid crystal polyester pellet 1 (Vectra C950 from Celanese), as the low melting point liquid crystal polymer resin, liquid crystal polyester pellet 2 (Vectra A950 from Unitika) and polyarylate pellet 3 (U-Polymer U-100) were mixed, and then using a twin-screw extruder, mixed pellets in which the above components were mixed were produced (the temperature of the extruder was about 320 °C).

[0090] The mixed pellets of Example 1 were those in which each component was mixed at a predetermined content level so as to satisfy the film viscosity and elastic modulus of this application. When producing 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 produced as described above were put into a single-screw extruder (manufactured by Labtech, LE30-30 / CV) to produce a film with a thickness of 50 μm. At this time, the L / D of the extruder was 30 and the diameter was 30 mm. A T-die was applied for the die, the slit interval of the die was 0.5 mm, and the slit width was 300 mm. Also, the temperature of the extruder was set to 380 °C, the die temperature was set to 350 °C, and the screw speed in the extruder was 65 rpm.

[0092] Examples 2 to 12 The same thermoplastic liquid crystal polyester pellets and polyarylate pellets as in Example 1 were used to produce a film with a thickness of 50 μm, with only the content (input amount) being different as shown in Tables 1 and 2 below. Similar to Example 1, the mixed pellets were those in which each component was mixed at a predetermined content level so as to satisfy the film viscosity of this application (see Tables 1-2 below).

[0093] Comparative Example 1 After mixing thermoplastic liquid crystal polyester pellets 1 (Vectra C950 from Celanese Corporation) and polyarylate pellets 3 (U-Polymer U-100), mixed pellets in which the above components were mixed were produced using a twin-screw extruder (the temperature of the extruder was approximately 320°C).

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

[0095] The mixed pellets of Comparative Example 1 were put into a single-screw extruder (manufactured by Labotech, LE30-30 / CV) to produce a film with a thickness of 50 μm. At this time, the film production conditions were the same as those described in Example 1.

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

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

[0098] Characteristic evaluation of film For the films of the examples and comparative examples, the viscosity, dielectric constant, dielectric tangent, adhesive strength, heat resistance, surface roughness of the copper foil before etching, and surface roughness of the film surface after etching of the films 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) Using a microwave molecular orientation analyzer (MOA-7015, manufactured by Oji Scientific Instruments Co., Ltd.), the dielectric constant and dielectric loss tangent of the films of the examples and comparative examples were measured. The frequency applied during the measurement was 15 GHz.

[0100] *Film viscosity (poise) Using a capillary rheometer, the melt viscosity of the films of each example and comparative example was determined at 320°C. The capillary rheometer had a die with a length of 20 mm and a diameter of 1 mm, and a piston diameter of 12 mm, and the melt viscosity at a shear rate of 500 / second was determined.

[0101] *Surface roughness before and after etching (μm) 1) Copper foil etching (etching): A copper foil (JX Metals Co., Ltd., JXEFL-V2) with a thickness of 12 μm was prepared. For adhesion evaluation, a copper foil / (each example or comparative example) film / copper foil laminate was produced. Then, after cutting the laminate into a size of 10 mm in width and 20 mm in length, it was immersed in a ferric chloride (FeCl3·6H2O, Iron(III) Chloride anhydrous) solution (with a concentration of about 97%) for 30 minutes and then washed with running water.

[0102] 2) Surface roughness of the copper foil before etching and surface roughness of the film surface after etching: The arithmetic mean surface roughness was measured using a 3D Optical Profiler (NPFLEX manufactured by Bruker). Specifically, in the Vertical Scanning Interferometry (VSI) mode, the magnification of the microscope was set to 50 times, and after measuring the surface image with a size of 95 μm in length and 126 μm in width, the arithmetic mean surface roughness was determined with a Cut-off of 800 μm. That is, the surface roughness is measured for the unevenness having a wavelength below the Cut-off value. For reference, the surface roughness of the film surface after etching means the surface roughness of the film surface where the copper foil was located before etching in the film surface, but from which copper has been removed by the etching process.

[0103] * Adhesion force (kN / m) The liquid crystal polymer film was inserted between two copper foils, and after forming a laminate using hot pressing, the adhesion force was determined by the force generated while peeling the copper foil.

[0104] After cutting the film into a size of 50 mm in width and 150 mm in length, it was inserted between two 12-μm copper foils (JX Metals Co., Ltd., JXEFL-V2) and laminated using hot pressing. The pressing pressure during hot pressing lamination was 20 MPa, and the hot pressing temperature was 300 °C.

[0105] After cutting the fabricated copper foil / film / copper foil laminate into a size of 25 mm in width and 150 mm in length to prepare a test piece for evaluation, the peeling force generated while peeling the copper foil was indicated as the adhesion force using a peeling force evaluation tester (Chem Instrument Co., Ltd., AR-1000).

[0106] * Elastic modulus (heat resistance) (MPa) For the films produced in the examples and comparative examples, the elastic modulus (E’) at 280°C was evaluated using a dynamic mechanical analyzer (DMA, DMA GABO EPLEXOR 100N manufactured by NETZSCH). The elastic modulus at 280°C was evaluated while increasing the temperature at a rate of 5°C / min under static strain of 0.15%, dynamic strain of 0.10%, and frequency of 1.0 Hz. When the evaluation sample broke during the evaluation and it was difficult to measure the elastic modulus, it was marked as unmeasurable.

[0107]

Table 1

[0108]

Table 2

[0109]

Table 3

[0110] Through the results in Tables 1 to 3 above, even when polyarylate resin is included, Examples 1 to 12 using two or more kinds of liquid crystal polymer resins with different melting points together show an optimal film viscosity that can suppress the increase in the viscosity of the resin composition and ensure excellent coating properties compared to Comparative Examples 1 to 5, and it can be confirmed that the adhesive force with the copper foil is improved.

[0111] Also, in Examples 1 to 12, the elastic modulus at 280°C measured under the above-mentioned conditions satisfied the range of 150 to 600 MPa.

[0112] On the other hand, in Comparative Examples 1 to 5, since one kind of low melting point or high melting point liquid crystal polymer was used or a mixture thereof could not satisfy the scope of the present application, the adhesive force with the copper foil was poor due to the increase in the viscosity of the film, 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, in the case of Comparative Examples 1 to 5, the heat resistance may become poor.

Claims

1. An insulating film laminated with a metal layer containing copper to form an FCCL (Flexible Copper Clad Laminate), wherein the insulating film satisfies a surface roughness ratio calculated by the following relational expression of 78% or more: [Relational expression] Ratio of surface roughness (%) = (S r2 / S r1 ) × 100 (In the above relational expression, S r1 is the arithmetic mean roughness of either one surface of the metal layer that forms the FCCL together with the insulating film, and is in the range of 0.1 to 0.6 μm, S r2 is the arithmetic mean roughness of either side of the insulating film, and is measured after the insulating film or the FCCL is immersed and washed in a ferric chloride (FeCl 3 ·6H 2 O, Iron(III) Chloride anhydrous) solution within 1 hour. the arithmetic mean roughness is measured with a cut-off criterion of 800 μm.)

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

3. The insulating film according to claim 1, having a film viscosity of 300 to 1,000 poise or less (wherein the film viscosity is measured at a shear rate of 320 °C and 500 / sec).

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

5. The insulating film according to claim 1, comprising a liquid crystal polymer and a polyarylate.

6. (A) A metal layer containing copper; and (B) A laminate including an insulating film located on at least one surface of the metal layer, wherein the insulating film satisfies a surface roughness ratio calculated by the following relational expression of 78% or more: [Relational expression] Ratio of surface roughness (%) = (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 in contact with the insulating film, and is in the range of 0.1 to 0.6 µm, S r2 is the arithmetic mean roughness of one surface of the insulating film facing or in contact with the metal layer, and is measured after the laminate is immersed and washed in a ferric chloride (FeCl 3 ·6H 2 O, Iron(III) Chloride anhydrous) solution within 1 hour, the arithmetic mean roughness is measured with a cut-off criterion of 800 μm.)

7. The laminate according to claim 6, wherein the insulating film has a film viscosity of 1,000 poise or less (wherein the film viscosity is measured at a shear rate of 320 °C and 500 / sec).

8. The laminate according to claim 7, wherein the insulating film has a film viscosity of 300 to 1,000 poise or less (wherein the film viscosity is measured at a shear rate of 320 °C and 500 / sec).

9. The laminate according to claim 6, wherein the insulating film satisfies an elastic modulus of 150 to 600 MPa at 280°C, which is confirmed when the temperature is increased at a rate of 5°C / min under the conditions of a static strain of 0.15%, a dynamic strain of 0.10%, and a frequency of 1.0 Hz.

10. The laminate according to claim 6, wherein the insulating film contains a liquid crystal polymer and a polyarylate.

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