Metal laminated sheet and printed circuit board comprising same

Abstract

The present invention relates to a metal laminate sheet and a printed circuit board, the metal laminate sheet comprising: a resin layer formed from a resin composition comprising: (a) a perfluoroalkoxyalkane (PFA); (b) one or more elastomers selected from the group consisting of styrene-based elastomers and fluorine-based elastomers; and (c) two or more types of inorganic fillers, and each of the two or more types of inorganic fillers satisfies specific relational expression 1 and relational expression 2.

Description

Technical Field

[0001] This invention relates to a metal laminate and a printed circuit board containing the same. Background Technology

[0002] In recent years, with the advent of the era of hyper-connected intelligence, including artificial intelligence, big data, and autonomous vehicles, the development and popularization of various electronic devices such as smartphones have accelerated. This has led to the comprehensive development of next-generation 5G communication, capable of transmitting large amounts of data wirelessly at high speeds, replacing existing 4G LTE communication. In particular, for the widespread adoption of autonomous vehicles, smart cities, and smart factories, next-generation 5G communication technology, capable of connecting and processing large amounts of data in real time without latency, has become essential. 5G operates at high frequencies (above 26 GHz), specifically millimeter-wave (mmWave) 5G, enabling the transmission of large amounts of data at once and ensuring high-precision images with high resolution. However, the higher the frequency band used by communication / electronic devices, the greater the transmission loss of electrical signals, which may lead to problems such as overheating, signal attenuation, and latency.

[0003] Therefore, low-roughness copper foil has been used in the past to minimize transmission losses in communication / electronic equipment in the high-frequency to ultra-high-frequency domains. However, when using low-roughness copper foil, the adhesion between the copper foil and the resin layer is too low. Therefore, inorganic fillers with larger average particle size have been used in the past to improve the adhesion between the copper foil and the resin layer. However, if the particle size of the inorganic filler is large, during the lamination process with the copper foil, the filler in the resin layer will increase the roughness of the copper foil surface due to heat and pressure, causing uneven or increased signal transmission losses, and the advantages of low-roughness copper foil will no longer exist. In addition, inorganic fillers with larger average particle size will increase the roughness of the inner wall during the hole formation process when processing into printed circuit boards, resulting in uneven plating and thus causing a decrease in reliability. Summary of the Invention

[0004] Technical issues

[0005] The present invention aims to provide a metal laminate with low signal transmission loss while maintaining low dielectric constant and low dielectric loss.

[0006] Furthermore, the present invention aims to provide a printed circuit board comprising the aforementioned metal laminate.

[0007] Methods for solving problems

[0008] To achieve the above objectives, the present invention provides a metal laminate comprising: a resin layer formed of a resin composition, and a metal foil disposed on at least one side of the resin layer, wherein the resin composition comprises: (a) a perfluoroalkoxyalkane (PFA); (b) one or more elastomers selected from the group consisting of styrene-based elastomers and fluoroelastomers; and (c) two or more inorganic fillers, wherein each of the two or more inorganic fillers satisfies the following relations 1 and relations 2:

[0009] [Relation 1]

[0010]

[0011] [Relationship 2]

[0012]

[0013] (In equations 1 and 2 above,

[0014] D1 is the average particle size of each inorganic filler.

[0015] T1 is the thickness of the resin layer.

[0016] D 90 (This refers to the cumulative 90% particle size of each inorganic filler in the volume-based particle size distribution measured by laser diffraction particle size distribution determination method).

[0017] Furthermore, according to one embodiment of the invention, the passive intermodulation distortion (PIMD) of the metal laminate can be below -150 dBc.

[0018] Furthermore, according to another embodiment of the present invention, after the through-hole is machined and metal is plated, the roughness (Rz) of the inner wall surface of the through-hole can be less than 20 μm.

[0019] Furthermore, according to another embodiment of the present invention, the rate of change (ΔRz / Rz1) of the surface roughness of the metal foil before and after hot pressing can be in the range of 0 to 0.5 (where ΔRz = Rz1 - Rz2, Rz1 is the surface roughness of the metal foil before hot pressing, and Rz2 is the surface roughness of the metal foil after hot pressing).

[0020] Furthermore, according to another embodiment of the present invention, the perfluoroalkoxyalkane comprises a tetrafluoroethylene repeating unit and a perfluoroether repeating unit, wherein the molar ratio of the tetrafluoroethylene repeating unit to the perfluoroether repeating unit can be in the range of 1:10 to 1:10000.

[0021] Furthermore, according to another embodiment of the present invention, the thickness of the resin layer can be in the range of 25 μm to 760 μm.

[0022] Furthermore, according to another embodiment of the present invention, the average particle size of each of the two or more inorganic fillers can be in the range of 0.1 to 5 μm.

[0023] Furthermore, according to one embodiment of the present invention, the two or more inorganic fillers may include: (c1) a first inorganic filler with an average particle size of 0.1 μm or more and less than 3 μm; and (c2) a second inorganic filler with an average particle size of 3 to 5 μm.

[0024] Furthermore, according to another embodiment of the present invention, the weight ratio of the first inorganic filler to the second inorganic filler may be from 99:1 to 50:50.

[0025] Furthermore, according to another embodiment of the present invention, based on 100% by weight of the composition, the resin composition may contain: 29 to 70% by weight of perfluoroalkoxyalkane, 1 to 10% by weight of elastomer, and 29 to 70% by weight of inorganic filler.

[0026] Furthermore, according to another embodiment of the invention, the roughness Rz of the matte side of the metal foil can be in the range of 0.1 to 7 μm.

[0027] Furthermore, the present invention provides a printed circuit board comprising the aforementioned metal laminate.

[0028] Invention Effects

[0029] The metal laminate of the present invention maintains low dielectric constant and low dielectric loss characteristics while exhibiting excellent adhesion to metal foil and low signal transmission loss. Therefore, it can be advantageously used in printed circuit boards for mobile communication devices or their base station devices, network-related electronic devices such as servers and routers, automotive radar devices, large computers, and various electrical / electronic / communication devices that process high-frequency to ultra-high-frequency signals. Attached Figure Description

[0030] Figure 1 This is a schematic cross-sectional view of a metal laminate, illustrating an example of the present invention.

[0031] Explanation of reference numerals in the attached figures

[0032] 10: Resin matrix, 20: Inorganic filler, 100: Metal laminate, 110: Resin layer, 121: Metal foil, first metal foil, 122: second metal foil. Detailed Implementation

[0033] The present invention will now be described.

[0034] Unless otherwise defined, all terms used in this specification (including technical and scientific terms) are to be used in the sense that would be commonly understood by one of ordinary skill in the art to which this invention pertains. Furthermore, unless explicitly defined otherwise, terms as defined in commonly used dictionaries are not to be interpreted ideally or excessively.

[0035] Furthermore, throughout the specification, when it is stated that a certain part "contains" a certain component, unless there is a specific statement to the contrary, it should be understood as an open-ended term that covers other components rather than excluding them.

[0036] Furthermore, throughout the instruction manual, the terms "above" or "on ~ above" refer not only to the case where the object is located directly above or below it, but also to the case where there are other parts in between, and do not necessarily mean that it is located on the upper side based on the direction of gravity.

[0037] In addition, the terms "first" and "second" used in this specification do not indicate any arbitrary order or importance, but are used to distinguish the constituent elements from each other.

[0038] The metal laminate of the present invention can be applied to printed circuit boards, especially to printed circuit boards that can be used in the high frequency to ultra-high frequency band, comprising a resin layer and a metal foil disposed on at least one side of the resin layer.

[0039] According to one example, such as Figure 1 As shown, the metal laminate 100 includes a resin layer 110 and a first metal foil 121 and a second metal foil 122 respectively disposed on both sides of the resin layer 110.

[0040] It should be noted that the present invention aims to maintain the low dielectric constant and low dielectric loss characteristics of the resin layer 110 while ensuring the stability of signal transmission loss. To this end, the resin layer 110 is formed as a resin composition comprising: (a) a perfluoroalkoxyalkane (PFA), (b) one or more elastomers selected from the group consisting of styrene-based elastomers and fluorine-based elastomers, and (c) two or more inorganic fillers with different average particle sizes. Furthermore, the ratio of the resin layer thickness to the average particle size of each inorganic filler is adjusted to be very small, while the D0 of each inorganic filler is... 90 The values ​​are also adjusted to be very small. Therefore, the metal laminate 100 of the present invention not only has a low dielectric constant and low dielectric loss tangent in the frequency band of approximately 1 to 100 GHz, but also low signal transmission loss. Therefore, the metal laminate of the present invention can minimize the transmission loss of printed circuit boards used in high-frequency to ultra-high-frequency applications.

[0041] (1) Resin layer

[0042] In the metal laminate of the present invention, the resin layer 110 is an insulating support member formed by curing the resin composition, comprising: a resin matrix component 10 containing perfluoroalkoxyalkane and an elastomer; and two or more inorganic fillers 20. In this case, the ratio of the thickness of the resin layer of each inorganic filler in the two or more inorganic fillers 20 to the average particle size of the inorganic filler is very small, and D 90 It is also very small.

[0043] The components of the resin composition of the present invention will be described below.

[0044] (a) Perfluoroalkoxyalkanes

[0045] In the resin composition of the present invention, perfluoroalkoxyalkane, as a type of fluorine-containing (F) fluorine resin, enables the resin layer to achieve low dielectric constant and low dielectric loss characteristics. Such perfluoroalkoxyalkane is a solid particulate filler at room temperature, which is bonded to the resin layer by an elastomer during the drying of the resin composition, and melted in a hot pressing process at approximately 310°C or higher to form the matrix component of the resin layer together with the elastomer. Furthermore, unlike fluororesin dispersions, perfluoroalkoxyalkane does not contain a dispersant, thus improving the heat resistance and adhesion of the metal laminate.

[0046] According to one example, the perfluoroalkoxyalkane comprises a repeating tetrafluoroethylene (C2F4) unit and a perfluoroether (C2F3OR) unit. 1 , where R 1 C1~C12 (perfluoroalkyl) repeating unit.

[0047] At this point, the ratio of the tetrafluoroethylene repeating unit to the perfluoroether repeating unit is not particularly limited; for example, the molar ratio can be 1:10 to 1:10000. However, when the ratio of the tetrafluoroethylene repeating unit to the perfluoroether repeating unit is within the aforementioned range, the perfluoroalkoxyalkane can have a dielectric constant (Dk) of less than 2.2 and a dielectric loss tangent (Df) of less than 0.0003.

[0048] According to ISO 1133-1 test method, the melt flow rate (MFR) of the perfluoroalkoxyalkane at about 372 °C and about 2 kg can be about 1 to 30 g / 10 min.

[0049] The more uniformly such perfluoroalkoxyalkanes are dispersed in the resin composition, the better the dielectric properties of the resin composition are improved, and the more suitable it is for manufacturing metal laminates through a simple coating process without the need for high-temperature extrusion molding and high-temperature firing. Therefore, in this invention, it is preferable to adjust the shape, size (average particle size), and content of the perfluoroalkoxyalkanes within specific ranges.

[0050] Specifically, perfluoroalkoxyalkanes can be spherical, plate-like, dendritic, conical, pyramidal, or amorphous. Among these, spherical perfluoroalkoxyalkanes have the smallest surface area, which improves the processing characteristics of the resin composition and imparts isotropic properties to the resin layer.

[0051] Furthermore, the average particle size of the perfluoroalkoxyalkane can be in the range of about 0.1 to 100 μm, specifically in the range of 1 to 70 μm, and more specifically in the range of 5 to 50 μm. If the perfluoroalkoxyalkane has the aforementioned average particle size, the perfluoroalkoxyalkane is uniformly dispersed in the resin composition without agglomeration, thus making it suitable for fabricating resin layers for printed circuit boards.

[0052] In the resin composition of the present invention, the content of perfluoroalkoxyalkane is not particularly limited. However, if the content of perfluoroalkoxyalkane is too low, the adhesion between the resin layer and the metal foil (e.g., copper foil) in the metal laminate will decrease, potentially leading to foil peeling; while if the content of perfluoroalkoxyalkane is too high, the content of inorganic filler will be relatively low, which may result in an increase in the coefficient of thermal expansion (CTE) of the resin layer. Therefore, it is suitable to adjust the content of perfluoroalkoxyalkane to a range of about 29 to 70% by weight, based on the total amount (100% by weight) of the resin composition. In this case, the resin composition of the present invention can form a resin layer with excellent heat resistance and adhesion, and low dielectric constant and dielectric loss.

[0053] (b) Elastomers

[0054] In the resin composition of the present invention, the elastomer is an adhesive capable of bonding both inorganic fillers and perfluoroalkoxyalkanes. For example, the resin composition may contain a thermoplastic elastomer. In this case, the thermoplastic elastomer melts under high temperature and pressure, thereby readily forming a resin layer.

[0055] The elastomer of the present invention comprises one or more selected from the group consisting of fluorinated elastomers and styrene elastomers. These fluorinated and styrene elastomers not only readily bond inorganic fillers and perfluoroalkoxyalkanes, but also exhibit low dielectric properties. Specifically, the elastomer of the present invention has a dielectric loss tangent (Df) of 0.0005 to 0.0020 at 10 GHz. Furthermore, the elastomer of the present invention has a dielectric constant (Dk) of 2.0 to 3.0 at 10 GHz.

[0056] When the elastomer of the present invention, which has a low dielectric loss tangent and a low dielectric constant, is used as an adhesive, a resin layer with low dielectric loss can be easily formed by directly coating the resin composition onto a metal foil and drying it, without the need for a high-temperature extrusion molding process and a high-temperature firing process.

[0057] The fluorinated elastomer of the present invention, as a type of thermoplastic elastomer, is an elastomer containing one or more fluorine (F) atoms in at least one repeating unit. Such a fluorinated elastomer not only has a dielectric loss tangent (Df) of 0.0005 to 0.0020 and a dielectric constant of 2.0 to 3.0 at 10 GHz, but also has a low modulus.

[0058] Examples of fluorinated elastomers that can be used in this invention include: copolymers comprising two or more copolymers selected from the group consisting of vinylidene fluoride (VDF), hexafluoropropylene (HFP), and tetrafluoroethylene (TFE); tetrafluoroethylene-propylene copolymers; vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene copolymers; tetrafluoroethylene-perfluoroalkyl vinyl ether copolymers, etc., but are not limited thereto. They can be used alone or in combination of two or more copolymers.

[0059] According to one example, the fluoroelastomer can be one or more selected from the group consisting of FKM (fluorocarbon-based fluoroelastomer) and FFKM (perfluoroelastomer), specifically one or more selected from the group consisting of copolymers of: hexafluoropropylene (HFP) and vinylidene fluoride (VDF); a copolymer of tetrafluoroethylene (TFE), hexafluoropropylene (HFP) and vinylidene fluoride (VDF); a copolymer of tetrafluoroethylene (TFE), fluorinated vinyl ether and vinylidene fluoride (VDF); a copolymer of tetrafluoroethylene (TFE), propylene and vinylidene fluoride (VDF); or tetrafluoroethylene (TFE), hexafluoropropylene (HFP), ethylene, fluorinated vinyl ether. copolymers of vinylidene fluoride (VDF) and fluorinated vinyl ethers (e.g., perfluoromethylvinyl ether (PMVE)).

[0060] The fluorine (F) content in the fluorinated elastomer of the present invention is not particularly limited, but when the fluorine content per molecule of the fluorinated elastomer is in the range of about 60 to 80% by weight, the dielectric loss tangent of the fluorinated elastomer at 10 GHz can be in the range of about 0.0005 to 0.0020.

[0061] The styrene-based elastomer of the present invention, as a type of thermoplastic elastomer, is an elastomer containing one or more styrene groups within at least one repeating unit. Such a styrene-based elastomer can have a dielectric loss tangent Df of 0.0005 to 0.0020 and a dielectric constant of 2.0 to 3.0 at 10 GHz.

[0062] The styrene-based elastomers that can be used in this invention can be styrene mixed with C2~C364. 10These are copolymer elastomers of aliphatic unsaturated hydrocarbons. Specifically, examples of styrene-based elastomers include, but are not limited to, styrene-butadiene-styrene binary copolymers (SBS), styrene-ethylene-butene-styrene terpolymers (SEBS), styrene-ethylene-ethylene-propylene-styrene terpolymers (SEEPS), styrene-isoprene-styrene binary copolymers, and styrene-ethylene-propylene-styrene terpolymers. They can be used alone or in combination of two or more.

[0063] The styrene content in the styrene-based elastomer of the present invention is not particularly limited, but when the styrene content per molecule of the styrene-based elastomer is in the range of about 10 to 40% by weight, the dielectric loss tangent of the styrene-based elastomer at 10 GHz can be in the range of about 0.0005 to 0.0020.

[0064] According to ISO 1133-1 test method, the melt flow rate (MFR) of the elastomer of the present invention at 230 °C and 2 kg is about 0.1 g / 10 min or less. Furthermore, the viscosity of a solution in which 5 wt% of the elastomer of the present invention is dissolved in toluene is about 50 to 100 cps. Therefore, by adjusting the viscosity of the resin composition of the present invention to the range of about 150 to 500 cps, processability during the manufacture of metal laminates can be improved.

[0065] The elastomer of the present invention has a thermal decomposition temperature (Td) of up to about 350 °C. Therefore, the resin composition of the present invention can form a resin layer with excellent thermal stability at high temperatures.

[0066] In the resin composition of the present invention, the content of the elastomer is not particularly limited, and may range from about 1% to 10% by weight, based on the total amount of the resin composition. When the content of the elastomer is less than about 1% by weight, the effect of bonding the inorganic filler and the perfluoroalkoxyalkane may be reduced; while when the content of the elastomer exceeds about 10% by weight, the adhesion between the resin layer and the metal foil (e.g., copper foil) may be reduced, thereby causing the metal foil to peel off during the manufacture and use of the metal laminate.

[0067] (c) Inorganic packing

[0068] The resin composition of the present invention comprises an inorganic filler. The inorganic filler can reduce the difference in coefficient of thermal expansion (CTE) between the resin layer formed by the resin composition and other layers (e.g., metal foil), thereby effectively improving the warpage characteristics, low expansion, mechanical strength (toughness), and low stress of the final product.

[0069] It should be noted that, in this invention, in order to minimize the generation of parasitic frequency and burr on the inner wall of the through hole, and to minimize the change in surface roughness of the metal foil before and after the hot pressing process during the manufacturing of the metal laminate, two or more inorganic fillers with different average particle sizes are included, and each of the two or more inorganic fillers satisfies the following relation 1 and relation 2.

[0070] [Relation 1]

[0071]

[0072] [Relationship 2]

[0073]

[0074] (In equations 1 and 2 above,

[0075] D1 is the average particle size of each inorganic filler.

[0076] T1 is the thickness of the resin layer.

[0077] D 90 (This refers to the cumulative 90% particle size of each inorganic filler in the volume-based particle size distribution measured by laser diffraction particle size distribution determination method).

[0078] The passive intermodulation distortion (PIMD) of the metal laminate containing two or more inorganic fillers is below -150 dBc, minimizing the generation of parasitic frequencies. Furthermore, during through-hole processing and metal plating, the metal laminate of the present invention achieves a uniformly thick plating layer due to the low roughness (Rz) of the inner wall surface of the through-hole being below 20 μm. Moreover, the rate of change of the surface roughness of the metal foil before and after hot pressing (ΔRz / Rz1) of the metal laminate of the present invention is as low as 0 to 0.5, thus preventing unevenness or increase in signal transmission loss. Here, ΔRz = Rz1 - Rz2, where Rz1 is the surface roughness of the metal foil before hot pressing, and Rz2 is the surface roughness of the metal foil after hot pressing.

[0079] Specifically, the thickness (T1) of the resin layer is not particularly limited, and can be, for example, in the range of about 25 to 760 μm, more specifically, in the range of about 40 to 300 μm, and more specifically, in the range of about 50 to 200 μm. Considering the thickness of the cured product of such a resin composition, the average particle size of the two or more inorganic fillers can be in the range of about 0.1 to 5 μm.

[0080] The two or more inorganic fillers may include inorganic fillers having different average particle sizes and / or compositions from each other.

[0081] According to one example, the two or more inorganic packing materials may include: (a) a first inorganic packing material with an average particle size of 0.1 μm or more and less than 3 μm; and (b) a second inorganic packing material with an average particle size of 3 to 5 μm. In this case, the composition of the first inorganic packing material and the second inorganic packing material may be the same or different.

[0082] The mixing ratio of the first inorganic filler and the second inorganic filler is not particularly limited. As an example, the first inorganic filler and the second inorganic filler can be included in a weight ratio of 99:1 to 50:50, specifically 95:5 to 65:35. In this case, a resin layer with excellent electrical properties and excellent low dielectric loss characteristics at high frequencies in the millimeter-wave (mmWave) region can be formed.

[0083] The first inorganic packing may comprise one or more of the following groups: (a1) an inorganic packing of type 1A with an average particle size of 0.1 to 1 μm, and (a2) an inorganic packing of type 1B with an average particle size greater than 1 μm and less than 5 μm. In this case, the compositions of the inorganic packing of type 1A and the inorganic packing of type 1B may be the same or different.

[0084] When the first inorganic filler comprises both the first A inorganic filler and the first B inorganic filler, the mixing ratio of the first A inorganic filler and the first B inorganic filler is not particularly limited. For example, the first A inorganic filler and the first B inorganic filler can be included in a weight ratio of 99:1 to 50:50, specifically in a weight ratio of 70:30 to 50:50. In this case, the adhesion of the resin composition of the present invention to metal foils (e.g., copper foil) can be further improved.

[0085] Non-limiting examples of inorganic fillers that may be used in this invention include: silica such as natural silica, fused silica, amorphous silica, crystalline silica, etc.; boehmite, alumina, talc, glass (e.g., spherical glass), calcium carbonate, magnesium carbonate, magnesium oxide, clay, calcium silicate, titanium dioxide, antimony oxide, glass fiber, aluminum borate, barium titanate, strontium titanate, calcium titanate, magnesium titanate, bismuth titanate, titanium dioxide (e.g., TiO2), barium zirconate, calcium zirconate, boron nitride, silicon nitride, talc, mica, etc.

[0086] According to one example, the first inorganic filler may contain a silicon-based filler. Specifically, the first inorganic filler may be silica (e.g., SiO2), such as natural silica, fused silica, amorphous silica, crystalline silica, or silicon nitride (Si3N4). In this case, the second inorganic filler may be a second silicon-based filler that differs from the first inorganic filler in composition and / or average particle size. For example, the second inorganic filler may contain one or more selected from the group consisting of a second silicon-based filler different from the silicon-based filler and non-silicon-based fillers.

[0087] Specifically, the two or more inorganic fillers may include: (a) silica with an average particle size of 0.1 μm or more and less than 3 μm; and (b) alumina or titanium dioxide with an average particle size of 3 to 5 μm.

[0088] Such inorganic fillers can be used alone or in combination of two or more. Among them, since silica, alumina and titanium dioxide have low dielectric loss coefficients, they can reduce the difference in thermal expansion coefficients between the resin layer and the metal foil, while also reducing the dielectric constant and dielectric loss tangent of the resin layer.

[0089] Furthermore, the shape of inorganic fillers is not particularly limited; for example, they can be spherical, plate-like, dendrite-like, conical, pyramidal, or amorphous.

[0090] In the resin composition of the present invention, the content of inorganic filler is not particularly limited and can be appropriately adjusted according to the aforementioned warpage characteristics, mechanical properties, etc. However, if the content of inorganic filler is too high, it will be detrimental to moldability and may reduce the adhesion of the resin layer. For example, based on the total amount of the resin composition, the content of inorganic filler can be about 29 to 70% by weight.

[0091] On the other hand, in addition to the aforementioned elastomers, perfluoroalkoxyalkanes, and inorganic fillers, the resin composition of the present invention may further contain, as needed and without impairing its physical properties, additives such as flame retardants, other thermosetting or thermoplastic resins, ultraviolet absorbers, antioxidants, polymerization initiators, dyes, pigments, dispersants, thickeners, leveling agents, and colorants known in the art. The content of the additives can be used within the range known in the art; for example, based on the total amount of the resin composition, the content of the additives can be from about 0.0001 to 10% by weight.

[0092] The viscosity of the resin composition of the present invention can be adjusted according to the type or content of elastomers, perfluoroalkoxyalkanes, and inorganic fillers in the composition, for example, it can be about 150 to 500 cps. According to one example, when the resin composition has the aforementioned viscosity, the resin layer can be directly formed on the metal foil by roll-to-roll coating.

[0093] As described above, the resin composition of the present invention allows for the easy formation of metal laminates by directly coating and drying a resin layer containing a resin layer with low dielectric constant, low dielectric loss, and excellent stability in signal transmission loss, without the need for film-forming processes (paste extrusion, through-hole processing) and high-temperature firing processes. Furthermore, the resin composition of the present invention can be applied to substrates of various materials, such as polyimide (PI) substrates, to manufacture flexible metal laminates.

[0094] The dielectric constant (Dk) of the resin layer 110 of the present invention at 10 GHz can be from about 1.0 to 10.0, and the dielectric loss tangent (Df) can be from about 0.0001 to 0.0100.

[0095] Furthermore, the adhesion between the resin layer 110 and the first metal foil 121 and the second metal foil 122 is approximately 0.4 to 1.0 kgf / cm, which is higher than the standard required in the art (0.35 kgf / cm). Therefore, even if the surface roughness of the metal foil in contact with the resin layer is low, the present invention can reduce peeling between the resin layer and the metal foil.

[0096] Furthermore, the resin layer 110 may have a coefficient of thermal expansion (CTE) of approximately 15 to 50 ppm / °C. Therefore, the metal laminate of the present invention can effectively improve the warpage characteristics, reduce expansion, increase mechanical strength (toughness), and reduce stress of the printed circuit board.

[0097] Furthermore, the thickness of the resin layer 110 is not particularly limited; for example, it can be approximately 25 to 760 μm, specifically in the range of approximately 40 to 300 μm, and more specifically in the range of approximately 50 to 200 μm. In this case, it is advisable to adjust the thickness of the resin layer taking into account the thickness of the metal foil and the metal laminate.

[0098] (2) First and second metal foils

[0099] In the metal laminate of the present invention, the first metal foil 121 may be disposed on one side of the resin layer 110, and the second metal foil 122 may be selectively disposed on the other side of the resin layer 110. In this case, the first metal foil 121 and the second metal foil 122 may be the same as or different from each other.

[0100] In this invention, the first metal foil 121 and the second metal foil 122 can be used without particular restriction, as long as they are conventional metal compositions in the art that can be applied to metal laminates or printed circuit boards. For example, each metal foil can be a metal film selected from the group consisting of copper (Cu), iron (Fe), nickel (Ni), titanium (Ti), aluminum (Al), silver (Ag), and gold (Au), or an alloy film of two or more metals. For example, the first metal foil 121 and the second metal foil 122 can be copper foil, which has excellent conductivity and is inexpensive. In this case, conventional copper foils known in the art can be used without restriction, and all copper foils manufactured by rolling and electrolysis methods can be used.

[0101] Furthermore, the matte sides of the first and second metal foils are in contact with the resin layer, and the roughness (Rz) of the matte sides can be about 0.1 to 7 μm, specifically about 0.3 to 5 μm, and more specifically about 0.3 to 3 μm. In this case, the present invention exhibits excellent transmission characteristics in the high-frequency to ultra-high-frequency domain.

[0102] The thickness of the metal foil is not particularly limited; considering the thickness and mechanical properties of the final metal laminate, the thickness can be in the range of approximately 9 to 70 μm.

[0103] The passive intermodulation distortion (PIMD) of the aforementioned metal laminate of the present invention can be below -150 dBc, specifically in the range of -170 dBc to -150 dBc. Here, the passive intermodulation distortion was measured according to Experimental Example 1 below. Therefore, the printed circuit board using the metal laminate of the present invention can minimize signal transmission loss.

[0104] Furthermore, the metal laminate of the present invention produces fewer burrs on the inner wall of the through-hole during through-hole processing. For example, the roughness (Rz) of the inner wall surface of the through-hole can be about 20 μm or less, specifically 3 to 20 μm. Here, the roughness of the inner wall surface of the through-hole was measured according to Experimental Example 5 below. Therefore, when the metal laminate of the present invention is metal plated after through-hole processing, a coating of uniform thickness can be formed. In addition, the present invention eliminates the need for an additional deburring process to remove burrs.

[0105] Furthermore, the rate of change (ΔRz / Rz1) of the roughness of the metal foil before and after hot pressing of the metal laminate of the present invention can be in the range of 0 to 0.5 (where ΔRz = Rz1 - Rz2, Rz1 is the surface roughness of the metal foil before hot pressing, and Rz2 is the surface roughness of the metal foil after hot pressing). Here, the surface roughness of the metal foil before hot pressing is the roughness of the surface of the metal foil used as raw material; for the surface roughness of the metal foil after hot pressing, the roughness of the surface of the metal foil is measured by performing micro-sectioning on the metal laminate itself and observing the cross-section with an optical microscope, and the difference in roughness after hot pressing relative to the roughness before hot pressing is calculated.

[0106] On the other hand, the aforementioned metal laminate of the present invention can be manufactured by a variety of methods known in the art.

[0107] For example, a metal laminate (e.g., a copper foil laminate) can be manufactured by a method including the following steps: directly coating one side of a metal substrate (e.g., a copper film) with the aforementioned resin composition and drying it, thereby producing two resin-coated metal foils having a resin layer formed on one side of the metal substrate; and laminating the two resin-coated metal foils in such a way that the resin layers are in contact with each other and then hot-pressing them. However, the manufacturing method is not limited to the above; the steps of each process can be modified or selectively combined as needed.

[0108] The coating method for the resin composition is not particularly limited. For example, there is roll-to-roll coating, specifically comma coating, slit coating, curtain coating, etc.

[0109] The drying process of the resin composition can be carried out at a temperature of about 50 to 200°C for about 2 to 20 minutes, thereby forming a resin layer on the metal substrate. Thus, the present invention dries the resin composition only before the pressing process, without performing a high-temperature firing process above 350°C.

[0110] The two resin-coated metal foils may be identical or different from each other, each comprising a metal substrate and a resin layer disposed on one side of the metal substrate. In this case, the metal substrate and / or resin layer of each resin-coated metal foil may be identical or different from each other.

[0111] The lamination and hot-pressing process between the resin-coated metal foils can be performed for approximately 3 to 60 minutes at a temperature of approximately 280 to 370°C and a pressure of approximately 10 to 50 kgf / cm². For example, by using a hot-pressing device with a heating plate equipped with the aforementioned temperature conditions, the laminated resin-coated metal foils are hot-pressed under the aforementioned conditions to obtain a metal laminate with a resin layer. In particular, during lamination and pressing at a temperature of approximately 280 to 370°C, the interlayer adhesion between the resin layers is further increased because the perfluoroalkoxyalkanes in the resin layers of each resin-coated metal foil melt, allowing the resin layers to be integrated.

[0112] Before and after such a hot-pressing process, the surface roughness of the metal foil changes little. For example, the rate of change of the surface roughness of the metal foil (ΔRz / Rz1) before and after hot pressing can be in the range of 0 to 0.5 (where ΔRz = Rz1 - Rz2, Rz1 is the surface roughness of the metal foil before hot pressing, and Rz2 is the surface roughness of the metal foil after hot pressing). Thus, in the resin composition of the present invention, the ratio of the thickness of the resin layer to the average particle size of the inorganic filler is very small. Therefore, the metal foil is not locally pressed by the inorganic filler, and the roughness of the metal foil hardly changes. Therefore, the metal foil in the metal laminate of the present invention can maintain a low roughness before and after hot pressing, thus avoiding unevenness or increase in transmission loss.

[0113] Printed Circuit Boards

[0114] On the other hand, the present invention provides a printed circuit board comprising the aforementioned metal laminate.

[0115] For example, a printed circuit board includes the metal laminate, on which circuit patterns can be formed of metal foils (a first metal foil and / or a second metal foil). In this case, the resin layer included in the metal laminate functions as an insulating support member.

[0116] For example, a printed circuit board includes the aforementioned metal laminate and one or more unit laminates disposed on the metal laminate, wherein the unit laminate includes a second resin layer and a third metal foil disposed on the second resin layer. In this case, the second resin layer, as an interlayer resin layer, may be a resin layer formed from the aforementioned resin composition, or a resin known in the art, such as a resin layer formed from polyimide.

[0117] The printed circuit board of the present invention can be manufactured using conventional methods known in the art. For example, the printed circuit board of the present invention can be manufactured by forming a circuit by creating holes in the aforementioned metal laminate, performing through-hole plating, and then etching the metal foil containing the plating film.

[0118] Because the printed circuit board of the present invention comprises metal laminates with low dielectric constant and dielectric loss tangent in the frequency band of approximately 1 GHz to 100 GHz, the dielectric loss in the approximately 1 GHz to 100 GHz frequency band is low, resulting in low transmission loss. Therefore, the printed circuit board of the present invention can be effectively applied to various electrical, electronic, and communication devices such as mobile communication devices or their base station devices that process high-frequency to extremely high-frequency signals, network-related electronic devices such as servers and routers, mainframe computers, and automotive radar equipment.

[0119] The present invention will be specifically described below through embodiments, but the following embodiments and experimental examples are merely illustrative of one aspect of the present invention, and the scope of the present invention is not limited to the following embodiments and experimental examples.

[0120] <Example 1> - Manufacturing of Copper Foil Laminates

[0121] The resin composition of Example 1, having the components listed in Table 1 below, was coated to a thickness of 75 μm onto one side of a copper foil [roughness (Rz): 6 μm] and dried at 140°C for 10 minutes to obtain resin-coated copper (RCC). Two resin-coated copper foils were then stacked in such a manner that the resin layers were in contact with each other, and hot-pressed (hot plate temperature: 340°C, pressure: 30 kgf / cm²) for 30 minutes to produce a copper foil laminate. In Tables 1 and 2 below, the content of each component is expressed in wt%, based on the total amount of the resin composition (100 wt%). Furthermore, in Tables 1 and 2 below, D1 / T1 refers to the ratio of the thickness (T1) of the resin layer to the average particle size (D1) of each inorganic filler. In addition, the average particle size of the inorganic filler was determined according to the ASTM D4464 test standard, and the roughness of the copper foil surface was determined according to the IPC-TM-650 2.2.17 test standard.

[0122] <Examples 2-3>

[0123] The resin compositions of Examples 2-3, having the compositions shown in Table 1 below, were used instead of the resin composition used in Example 1. Otherwise, the same method as in Example 1 was performed to manufacture the copper foil laminate.

[0124] <Example 4>

[0125] The resin composition of Example 4, having the composition shown in Table 2 below, was used instead of the resin composition used in Example 1, and the copper foil [roughness (Rz) of the rough surface: 1.7 μm] shown in Table 2 below was used instead of the copper foil [roughness (Rz) of the rough surface: 6 μm] used in Example 1. Otherwise, the copper foil laminate was manufactured by the same method as in Example 1.

[0126] <Examples 5-6>

[0127] The resin compositions of Examples 5-6, having the compositions shown in Table 2 below, were used instead of the resin compositions used in Example 1, and the copper foil [roughness (Rz) of the rough surface: 1.7 μm] shown in Table 2 below was used instead of the copper foil [roughness (Rz) of the rough surface: 6 μm] used in Example 1. Otherwise, the copper foil laminates were manufactured using the same method as in Example 1.

[0128] <Comparative Examples 1-5>

[0129] The resin compositions of Comparative Examples 1 to 5, having the compositions shown in Table 1 below, were used instead of the resin compositions used in Example 1. Otherwise, the same method as in Example 1 was performed to manufacture the copper foil laminate.

[0130] <Comparative Examples 6-10>

[0131] The resin compositions of Comparative Examples 6 to 10, having the compositions shown in Table 2 below, were used instead of the resin compositions used in Example 1, and the copper foil [roughness (Rz) of the rough surface: 1.7 μm] shown in Table 2 below was used instead of the copper foil [roughness (Rz) of the rough surface: 6 μm] used in Example 1. Otherwise, the copper foil laminates were manufactured by the same method as in Example 1.

[0132] [Table 1]

[0133]

[0134] [Table 2]

[0135]

[0136] <Experimental Example 1> - Passive Intermodulation Distortion (PIMD)

[0137] The passive intermodulation distortion of printed circuit boards containing copper foil laminates of Examples 1-6 and Comparative Examples 1-10 was measured as follows, and the results are shown in Tables 3 and 4, respectively.

[0138] A Cu circuit layer (impedance: 50 Ω) is formed on a copper foil laminate, thereby forming a printed circuit board. After inputting frequencies of 3630 MHz and 3660 MHz to the printed circuit board, the intensity of the reflected signal at 43 dBm is measured.

[0139] [Table 3]

[0140]

[0141] [Table 4]

[0142]

[0143] As shown in Tables 3 and 4, the PIMd of the printed circuit board containing the copper foil laminates of Examples 1-6 is -150 dBc or less, while the PIMd of the printed circuit board containing the copper foil laminates of Comparative Examples 1-10 is -145 dBc or more. Thus, it is confirmed that when the resin composition of the present invention is applied as a resin layer to the copper foil laminate and the printed circuit board, the generation of parasitic frequencies is low, thereby preventing a decline in transmission and reception quality.

[0144] <Experimental Example 2> - Peel Strength (P / S)

[0145] The peel strength between the resin layer and the copper foil in the copper foil laminates of Examples 1-6 and Comparative Examples 1-10 was measured according to the test standard of IPC TM-650.2.4.8. The test results are shown in Tables 5 and 6 below.

[0146] [Table 5]

[0147]

[0148] [Table 6]

[0149]

[0150] As shown in Tables 5 and 6, the peel strength between the resin layer and the copper foil in Examples 1 to 6 is lower than that in Comparative Examples 1 to 10. However, they still meet the standards required in the art.

[0151] <Experimental Example 3> - Dielectric constant and dielectric loss tangent

[0152] The dielectric constant (Dk) and dielectric loss tangent (Df) of the resin layer in the copper foil laminates of Examples 1-3 and Comparative Examples 1-5 were measured according to the test standard of IEC 61189-2-721:2015, and the results are shown in Table 7.

[0153] At this point, after removing the copper foil by immersing the copper foil laminate in an etching solution (hydrochloric acid: hydrogen peroxide = 1:2 volume ratio), the dielectric constant (Dk) and dielectric loss tangent (Df) of the resin layer at a frequency of 10 GHz are measured using a dielectric constant measuring device (RF Impedance / Material Analyzer; Agilent).

[0154] [Table 7]

[0155]

[0156] As shown in Table 7, the dielectric constant and dielectric loss tangent of the resin layer in the copper foil laminates of Examples 1-3 are the same as or similar to those of the resin layer in the copper foil laminates of Comparative Examples 1-5. Thus, it can be confirmed that even if the resin composition of the present invention contains two or more inorganic fillers with small average particle size, the low dielectric loss characteristics are still excellent.

[0157] <Experiment Example 4> - Signal Loss

[0158] Circuit layers (impedance: 50Ω) were formed on each copper foil laminate manufactured in Examples 1-6 and Comparative Examples 1-10. Then, for the copper foil laminates with the circuit layers formed, the transmission loss at a frequency of 77GHz was measured using a dielectric constant measuring device (Vector Network Analyzer, Keysight Technologies N5225B) according to the IPC TM 2.5.5.14 test standard. The dB (logarithmic amplitude) values ​​are shown in Tables 8 and 9 using the S-parameter values ​​of S21 and S12.

[0159] [Table 8]

[0160]

[0161] [Table 9]

[0162]

[0163] As shown in Tables 8 and 9, the copper foil laminates of Examples 1-3 exhibited lower signal loss compared to the copper foil laminates of Comparative Examples 1-5, which used the same copper foil. Furthermore, the copper foil laminates of Examples 4-6 exhibited lower signal loss compared to the copper foil laminates of Comparative Examples 6-10, which used the same copper foil. Moreover, the copper foil laminates of Examples 4-6 exhibited lower signal loss compared to the copper foil laminates of Examples 1-3, which used copper foil with a higher surface roughness.

[0164] Thus, it can be confirmed that when the resin composition of the present invention is applied to copper foil laminates, the stability of signal transmission loss can be ensured.

[0165] <Experimental Example 5> - Hole Wall Roughness

[0166] After laser via hole processing was performed on the copper foil laminates of Examples 4-6 and Comparative Examples 6-10, copper (Cu) plating was applied. The surface roughness (Rz) of the inner wall of the formed hole was then measured as follows, and the results are shown in Table 10.

[0167] Micro-sections were performed on the holes of the plated copper foil laminate, and the surface roughness (Rz) of the inner wall of the holes was numerically calculated using an optical microscope. At this time, the holes were inverted trapezoidal in shape. The degree (height) (μm) of the burr protruding into the hole when the upper and lower starting points of the hole were connected by a straight line was measured, and the surface roughness (Rz) of the inner wall of the hole was obtained from this measurement.

[0168] [Table 10]

[0169]

[0170] As shown in Table 10, the surface roughness of the inner wall of the holes in the copper foil laminates of Examples 4-6 is very low compared to that of the copper foil laminates of Comparative Examples 6-10. Thus, it can be confirmed that when the resin composition of the present invention is applied to the copper foil laminate, a coating of uniform thickness is formed on the inner wall of the hole during hole processing, and no additional deburring process is required.

[0171] <Experiment Example 6> - Does the surface roughness of the metal foil change before and after hot pressing?

[0172] To determine whether the surface roughness of the metal foil in the copper foil laminates of Examples 1-6 and Comparative Examples 1-3 and 6-10 changed before and after hot pressing, the following measurements were taken, and the results are shown in Table 11.

[0173] Micro-sections were performed on the copper foil laminates manufactured in Examples 1-6 and Comparative Examples 1-3 and 6-10, respectively. The surface roughness (Rz) of the copper foil after hot pressing was measured by observing the cross-section with an optical microscope, and the difference (ΔRz) between the surface roughness and the roughness of the copper foil before processing was calculated. The surface roughness (Rz) is the ten-point average roughness.

[0174] [Table 11]

[0175]

Claims

1. A metal laminate comprising: a resin layer formed of a resin composition, and a metal foil disposed on at least one side of the resin layer. The resin composition comprises: (a) Perfluoroalkoxyalkanes (PFA); (b) an elastomer selected from one or more elastomers grouped together with styrene-based elastomers and fluoroelastomers; and (c) Two or more inorganic fillers Among the two or more inorganic packing materials, each inorganic packing material satisfies the following relationships 1 and 2: [Relation 1] [Relation 2] In Equations 1 and 2 above, D1 is the average particle size of each inorganic filler. T1 is the thickness of the resin layer. D 90 The cumulative 90% particle size of each inorganic filler in the volume reference particle size distribution measured by laser diffraction particle size distribution determination method.

2. The metal laminate according to claim 1, wherein the passive intermodulation distortion (PIMD) of the metal laminate is below -150 dBc.

3. The metal laminate according to claim 1, wherein after through-hole processing and metal plating, the roughness Rz of the inner wall of the through-hole is less than 20 μm.

4. The metal laminate according to claim 1, wherein, during the manufacturing of the metal laminate, the rate of change of surface roughness ΔRz / Rz1 of the metal foil before and after hot pressing is in the range of 0 to 0.5, wherein, ΔRz = Rz1 - Rz2, where Rz1 is the surface roughness of the metal foil before hot pressing and Rz2 is the surface roughness of the metal foil after hot pressing.

5. The metal laminate according to claim 1, wherein the perfluoroalkoxyalkane comprises a tetrafluoroethylene repeating unit and a perfluoroether repeating unit. The molar ratio of the included tetrafluoroethylene repeating unit to the perfluoroether repeating unit ranges from 1:10 to 1:10000.

6. The metal laminate according to claim 1, wherein the thickness of the resin layer is in the range of 25 to 760 μm.

7. The metal laminate according to claim 1, wherein the average particle size of each of the two or more inorganic fillers is in the range of 0.1 to 5 μm.

8. The metal laminate according to claim 1, wherein the two or more inorganic fillers comprise: (a) The first inorganic filler with an average particle size of 0.1 μm or more and less than 3 μm; and (b) A second inorganic filler with an average particle size of 3 to 5 μm.

9. The metal laminate according to claim 8, wherein the first inorganic filler comprises: Inorganic filler No. 1A with an average particle size of 0.1 to 1 μm; and Inorganic filler No. 1B has an average particle size greater than 1 μm and less than 3 μm.

10. The metal laminate according to claim 8, wherein the first inorganic filler contains a silicon-based filler.

11. The metal laminate according to claim 8, wherein the second inorganic filler comprises one or more selected from the group consisting of silicon-based fillers and non-silicon-based fillers, which are different from the first inorganic filler.

12. The metal laminate according to claim 8, wherein the weight ratio of the first inorganic filler to the second inorganic filler is 99:1 to 50:

50.

13. The metal laminate according to claim 1, wherein, based on 100% by weight of the composition, the resin composition comprises: 29-70% by weight of perfluoroalkoxyalkanes, 1 to 10% by weight of elastomers, and 29-70% by weight of inorganic fillers.

14. The metal laminate according to claim 1, wherein the roughness Rz of the rough surface of the metal foil is in the range of 0.1 to 7 μm.

15. A printed circuit board comprising a metal laminate according to any one of claims 1 to 14.

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