Composite material and copper-clad laminate made therefrom

Abstract

To provide a composite material and a copper-clad laminate produced therefrom.SOLUTION: Disclosed is a composite material comprising a copper foil having at least one smooth surface and an adhesive layer having low Gk and Df properties. Also disclosed is a copper-clad laminate prepared by laminating the composite material with a flexible or rigid substrate, which exhibits heat resistance and good to excellent bond strength. The PCBs manufactured therefrom exhibit low insertion loss and may be assembled with other components to form a variety of electrical devices that utilize at least 1Gps high speed or at least 1GHz high frequency signals.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to composite materials for producing copper clad laminates that exhibit reduced conductor loss, dielectric loss and high peel strength. [Background technology]

[0002] Nowadays, to increase the information processing speed of electronics and handle high-frequency wireless communication, high-speed transmission of electrical signals is required for electronic components. The application of high-frequency matching substrates is also advancing. Therefore, low insertion loss has become one of the crucial properties of copper clad laminates (CCL) that are made into printed circuit boards for high-speed and / or high-frequency applications.

[0003] Reducing total insertion loss, which is the sum of conductor loss and dielectric loss, can be achieved by reducing conductor loss and / or dielectric loss. Reducing dielectric loss can be achieved by carefully selecting dielectric materials with low Dk (dielectric constant, also known as relative permittivity) and Df (dissipation factor, also known as loss tangent, tan δ), including the substrate, prepreg, and adhesives, if present at the interface between the copper foil and the substrate. Under high-speed / high-frequency conditions, signal transmission current is primarily conducted across the surface of the copper foil, a well-known phenomenon known as the skin effect. The skin effect is a phenomenon in which a larger amount of current is concentrated at the surface of the conductor due to higher frequencies. The current density decreases with increasing depth from the surface. The depth providing 1 / e (e is the natural logarithm) of the current density value on the surface is called the skin depth and serves as an indicator of the depth to which current flows. Skin depth is frequency-dependent and decreases as the frequency increases.

[0004] Typically, the surface of copper foil used for copper clad laminates that is laminated to a substrate is processed to form a roughened surface with protrusions (or nodules). This roughened surface is created to provide an adhesive effect to the substrate. The adhesive strength between the substrate and the copper foil can therefore be increased to ensure the reliability of the printed circuit board manufactured therefrom. Reducing surface roughness is one of the most effective ways to reduce conductor loss, but the tradeoff is a weakening of adhesive strength, as measured by the peel strength between the copper foil and the substrate. As a result, the final product (printed circuit board) may have poor reliability and performance in the high-frequency range (i.e., above 1 GHz). One approach to maintaining peel strength with lower surface roughness is to modify the morphology of the nodules, such as their shape, density, size, etc., during the Cu roughening process. For example, S.-Q. Lin et al. have disclosed in (Non-Patent Document 1) and (Non-Patent Document 2).

[0005] Another approach is to pretreat the unroughened side of the copper foil with an adhesion promoter or coupling agent. For example, T. Sato et al. (Patent Document 1) disclose that a silane coupling agent layer is formed on the unroughened side of the copper foil, and then a primer resin layer is formed thereon. An obvious drawback is that the excess adhesion promoter applied on the primer resin usually increases the dielectric loss due to its high Dk / Df characteristics, resulting in a higher overall insertion loss of the copper clad or PCB device, even though the conductor loss of the copper foil is reduced.

[0006] T. Matsunaga et al. also disclosed in Non-Patent Document 3 that the peel strength, rust prevention ability, heat resistance, or chemical resistance of copper foil can be increased by using a number of non-copper elements such as nickel or silane. However, these non-copper elements have higher magnetic permeability or higher electrical resistivity, which significantly increases the insertion loss of copper clad or PCB. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] U.S. Patent No. 8,815,387 [Patent Document 2] U.S. Patent No. 5,861,076 [Patent Document 3] U.S. Patent No. 4,521,558 [Patent Document 4] U.S. Patent No. 9,688,704 [Patent Document 5] European Patent Application Publication No. A-0251490 [Patent Document 6] U.S. Patent No. 10,385,076 [Patent Document 7] US Patent Application Publication No. 2016 / 0137889A1 [Non-patent literature]

[0008] [Non-Patent Document 1] TW M543248 [Non-patent document 2] TW M543249 [Non-patent document 3] TW I339222 Summary of the Invention [Problem to be solved by the invention]

[0009] There is a continuing need for composite materials with low conductor loss, low dielectric loss, and sufficiently high peel strength to prepare copper clad laminates and printed circuit boards suitable for use in high speed and / or high frequency applications. [Means for solving the problem]

[0010] The present invention provides a composite material for producing a copper clad laminate, comprising a copper foil and an adhesive layer, Copper foil: 0.170gΩ / m 2 and at least one smooth surface, the smooth surface having a surface roughness (Rz) of 2.0 μm or less, 1 particle / μm2 The total content of non-copper metallic elements on the smooth surface is less than 350 μg / dm 2 The following is true: The adhesive layer is derived from a mixture including a resin matrix containing about 5 to 25 parts by weight of a reactive resin, about 0.1 to 3 parts by weight of a curing agent, and about 72 to 94.9 parts by weight of a styrene-based rubber; and about 0 to 100 parts by weight of an additive, based on 100 parts by weight of the resin matrix; The adhesive layer is in contact with the smooth surface of the copper foil; the cured adhesive layer has a Dk value of 3.0 or less and a Df value of 0.006 or less at 10 GHz; provided that the smooth side of the copper foil is not pre-treated with an adhesion promoter to provide a composite material.

[0011] The present invention also provides copper clad laminates, copper clad circuits and devices comprising the composite materials of the present invention. [Brief explanation of the drawings]

[0012] [Figure 1] An enlarged side view of one embodiment of the composite laminate 100 is shown, having a layer structure of copper foil 1 and adhesive layer 2, with first surface 11 and second surface 12, where second surface 12, which is a smooth surface, is in contact with adhesive layer 2. [Figure 2] 1 shows an enlarged side view of one embodiment of the present copper clad laminate 200, which is a single-sided CCL having a layer configuration in the following order: the present composite material 100, which is composed of copper foil 1 and adhesive layer 2; and substrate 3, which is in contact with adhesive layer 2. [Figure 3] 1 shows an enlarged side view of one embodiment of the present copper clad laminate 300, which is a double-sided CCL having a layer structure in the following order: the present composite material 100, which is composed of copper foil 1 and adhesive layer 2; substrate 3; optional adhesive layer 4 and second copper foil 5, where second copper foil 5 and copper foil 1 can be the same or different; if adhesive layer 4 is present, adhesive layer 4 and second copper foil 5 can also be the same or different from composite material 100 in this embodiment of the present composite material 110. [Figure 4]A visual comparison of micrographs of the smooth side of Copper Foil 4A (having a surface roughness (Rz) of 0.62 μm) versus the rough side of Copper Foil 4B (having a surface roughness of 3.57 μm and a nodule density of 1.5 nodules / μm, purchased from Fukuda) is shown. DETAILED DESCRIPTION OF THE INVENTION

[0013] All publications, patent applications, patents, and other references mentioned herein are expressly incorporated by reference in their entirety for all purposes as if fully set forth, unless otherwise stated.

[0014] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In case of conflict, the present specification, including definitions, will control.

[0015] Unless otherwise specified, all percentages, parts, ratios, etc. are by weight.

[0016] As used herein, the term "produced from" is synonymous with "comprising." As used herein, the terms "comprise," "including," "include," "including," "have," "having," "contain," or "containing," or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or device that includes a list of elements is not necessarily limited to only those elements and may include other elements not expressly listed or inherent in such composition, process, method, article, or device.

[0017] The transitional phrase "consisting of" excludes any element, step, or ingredient not specified. When in a claim, such a phrase excludes from the claim the inclusion of materials other than those recited, except for impurities ordinarily associated therewith. When the phrase "consisting of" appears in a clause in the body of a claim rather than immediately following a preamble, it limits only the elements recited in that clause; other elements are not excluded from the claim as a whole.

[0018] The transitional phrase "consisting essentially of" is used to define a composition, method, or apparatus that includes materials, steps, features, components, or elements in addition to those literally contemplated, provided that these additional materials, steps, features, components, or elements do not materially affect the basic and novel characteristics of the claimed invention. The term "consisting essentially of" occupies a middle ground between "comprising" and "consisting of."

[0019] The term "comprising" is intended to include embodiments encompassed by the terms "consisting essentially of" and "consisting of." Similarly, the term "consisting essentially of" is intended to include embodiments encompassed by the term "consisting of."

[0020] When an amount, concentration, or other value or parameter is given as either a range, a preferred range, or a list of upper and lower preferred values, this should be understood to specifically disclose all ranges formed from any pairing of any upper range limit or preferred value with any lower range limit or preferred value, whether or not the ranges are individually disclosed. For example, if a range of "1 to 5" is recited, the recited range should be interpreted to include the ranges "1 to 4," "1 to 3," "1 to 2," "1 to 2 and 4 to 5," "1 to 3 and 5," etc. When a range of numerical values ​​is recited herein, unless otherwise specified, the range is intended to include its endpoints, and all integers and fractions within the range.

[0021] When the term "about" is used to describe a value or an endpoint of a range, the disclosure should be understood to include the specific value or endpoint referred to.

[0022] Furthermore, unless expressly stated to the contrary, "or" means an inclusive "or" and not an exclusive "or." For example, a condition A "or" B is satisfied by any one of the following: A is true (or exists) and B is false (or does not exist), A is false (or does not exist) and B is true (or exists), and A and B are both true (or exist).

[0023] "Mol%" or "mole %" means mole percent.

[0024] The embodiments of the present invention as described in the Summary of the Invention can be combined in any manner, including any other embodiment described herein, and the descriptions of variables in the embodiments relate not only to the composite laminate of the present invention but also to articles made therefrom.

[0025] The present invention is described in detail herein below.

[0026] copper foil Copper foils include rolled annealed (RA) copper foils and electrodeposited (ED) copper foils. Generally, ED copper foils have a matte side (deposit surface) and a shiny, glossy side (drum surface), while RA copper foils have both sides that are smooth. Because the composite is intended to be incorporated into CCLs and PCBs for high frequency and / or high speed applications, a suitable copper foil has a resistivity of 0.170 gΩ / m 2 The copper foil has a high purity with an electrical resistivity of 1. The copper foil has at least one smooth side characterized by a surface roughness (Rz) of 2.0 μm or less, as measured by the method described in the Examples section below. Furthermore, the smooth side has a surface roughness of 1.0 μm or less. 2 , or 0.5 pieces / μm 2 , or 0.3 pieces / μm 2 , or 0.1 pieces / μm 2For roughened copper foil surfaces, the nodule density is generally less than 3 / μm. 2 It is expected to have a nodule density of >.

[0027] As used herein, the smooth side of the copper foil is also referred to as the "lamination side" because it is the side that faces the substrate when the composite is used to make a CCL. The opposite side of the copper foil is referred to as the "resist side" (or wiring side).

[0028] In some cases, one or more passivation layers can be applied to one or both surfaces of the copper foil to provide additional desired properties such as rust prevention, heat resistance, and chemical resistance. Suitable materials for forming the passivation layer include non-copper metallic elements such as zinc, nickel, chromium, cobalt, molybdenum, tungsten, and combinations thereof. 2 Maintaining a total content of non-copper metallic elements on the smooth side of the copper foil of less than or equal to 100% allows for the retention of desired properties without compromising low conductor loss characteristics.

[0029] It should be noted that the surface characteristics of the resist side are subjected to many subsequent printed circuit manufacturing processes such as microetch, acid rinse, brown oxide, black oxide, pre-solder mask treatments, etc. It is understood that there are no requirements on the surface roughness and total content of deposited non-copper metallic elements.

[0030] Despite the presence of any passivation layer, the smooth surface of the copper foil is not treated with any adhesion promoter for use in improving adhesion between the copper foil and the substrate. Known adhesion promoters (also called coupling agents) for treating copper surfaces include silanes and silylamines disclosed in U.S. Patent No. 5,629,499 to Adlam et al. and U.S. Patent No. 5,629,499 to Sato et al.; allyl phosphite esters and allyl phosphate esters disclosed in U.S. Patent No. 5,629,499 to Mowdood; azole silanes disclosed in U.S. Patent No. 5,629,499 to Miura et al.; unsaturated amide-substituted heterocyclic compounds disclosed in U.S. Patent No. 5,629,499 to Mori et al.; and aminotriazine-based compounds disclosed in U.S. Patent No. 5,629,499 to Mori et al., and the numerous references cited therein.

[0031] The copper foil of the present composite material has a thickness ranging from about 6 μm to about 400 μm, or from about 12 μm to about 70 μm, or from about 18 μm to about 35 μm.

[0032] Copper foil suitable for use in the present composite material is commercially available from, for example, Chang Chun Petrochemical Co.; Nan Ya Plastics Co.; Mitsui Mining & Smelting Co.; Furukawa Electric Co.; or Fukuda Metal Foil & Powder Co.

[0033] adhesive layer The adhesive layer of the composite is in contact with the smooth side of the copper foil and is expected to provide good adhesion to the substrate to produce a copper clad laminate with a dielectric loss equal to or less than that of the substrate itself.

[0034] The adhesive layer is derived from a mixture containing a resin matrix containing about 5 to 25 parts by weight of a reactive resin, about 0.1 to 3 parts by weight of a curing agent, and about 72 to 94.9 parts by weight of a styrene-based rubber, and about 0 to 100 parts by weight of an additive, based on 100 parts by weight of the resin matrix.

[0035] Examples of reactive resins include epoxy resins, acrylic resins, phenolic resins, imide resins, or combinations thereof; preferably, epoxy resins.

[0036] Various epoxy resins can be used, such as bisphenol A type epoxy, bisphenol F type epoxy, phenol-novolac type epoxy, cresol-novolac type epoxy, glycidyl ether type epoxy, naphthalene type epoxy, etc. However, to properly control the reaction, it is preferable to use an epoxy resin containing at least two epoxy groups in each molecule. The above-mentioned epoxy resins can be used alone or in combination of two or more.

[0037] Depending on the type of epoxy resin used, those skilled in the art can easily select a suitable curing agent and then determine the appropriate amount according to the molar equivalent of the reactive resin. For example, the curing agent may include amines such as dicyanodiamide, imidazole, and aromatic amines; phenols such as bisphenol A and brominated bisphenol A; novolacs such as phenol novolac resins and cresol novolac resins; and acid anhydrides such as phthalic anhydride.

[0038] Examples of styrenic rubbers include polystyrene and block copolymers such as styrene-isoprene-styrene (SIS), styrene-butadiene-styrene (SBS), styrene-ethylene-butadiene-styrene (SEBS), styrene-ethylene-propylene-styrene (SEPS), or mixtures thereof.

[0039] Styrenic rubber can be grafted or copolymerized with unsaturated carboxylic acids and / or their anhydrides to obtain acid-modified rubber. Examples of unsaturated carboxylic acids or their anhydrides suitable for use as acid modifiers include maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, and itaconic anhydride. Maleic anhydride is particularly preferred. The use of acid-modified rubber can further improve adhesive reliability without increasing Dk and / or Df values.

[0040] The graft ratio of the acid-modified product is, for example, about 0.05% by weight to 10.0% by weight, preferably about 0.1% by weight to 5.0% by weight, based on the grafted styrene-based rubber. If the graft ratio is below the above range, the adhesive strength may be insufficient. On the other hand, if the graft ratio is above the above range, the styrene-based rubber may aggregate, and the compatibility and dispersibility may decrease, which tends to result in a decrease in production efficiency.

[0041] In the present invention, various additives can be added to the mixture forming the adhesive layer to provide beneficial functionality. For example, suitable additives include, but are not limited to, adhesion promoters, antioxidants, antistatic agents, colorants, fillers, flame retardants, impact modifiers, lubricants, processing aids, heat stabilizers, UV absorbers, etc. The additives can be added to the resin mixture as long as they do not impair the effects of the present invention.

[0042] Examples of useful fillers and flame retardants for the present mixture include, but are not limited to, aluminum oxide, organic phosphates, silica, calcium carbonate, magnesium carbonate, magnesium calcium carbonate, calcium oxide, magnesium oxide, talc, magnesium silicate, aluminum silicate, magnesium aluminum silicate, calcium silicate, clay, mica, barium sulfate, boron nitride, aluminum nitride, barium titanate, strontium titanate, aluminum trihydrate, and calcium sulfate.

[0043] The mixture that forms the adhesive layer is preferably mixed with a solvent that is capable of dissolving or dispersing the reactive resin, styrenic rubber, optional additives, and curing agent.

[0044] Suitable solvents include, for example, methyl ethyl ketone, toluene, methylcyclohexane, tetrahydrofuran, chlorobenzene, trichloroethylene, and methylene chloride, as long as the solvent does not adversely affect the adhesive properties of the resin mixture. These solvents can be optionally mixed depending on the composition of the resin mixture. For example, a mixture of methyl ethyl ketone and toluene at a ratio of 1:1 to 100 can be used.

[0045] The solids content of the mixture that forms the adhesive layer is about 10% by weight to about 60% by weight, or about 15% by weight to about 45% by weight, based on the total weight of the mixture.

[0046] In addition to having good adhesive strength, suitable resin mixtures preferably have low Df and Dk values ​​after curing. Evaluation can be performed by applying the resin mixture to a peelable substrate to form a 25 μm thick adhesive layer. After stacking, drying, and fully curing, Df and Dk were measured according to the method described in the Examples section below.

[0047] The inventors have discovered that the cured adhesive layer preferably has a Dk at 10 GHz of 3.0 or less, or 2.5 or less, and a Df at 10 GHz of 0.0060 or less, or 0.0040 or less, or 0.0020 or less.

[0048] Suitable resin mixtures can be prepared according to the adhesive compositions disclosed in U.S. Patent No. 5,629,999, or can be purchased from commercial sources such as Pyralux® GPL or Pyralux® GFL manufactured by DuPont.

[0049] Composite material of the present invention The composite material 100 of the present invention comprises a copper foil 1 and an adhesive layer 2, where the copper foil has a first surface 11 and a second (i.e., smooth) surface 12. The mixture forming the adhesive layer was applied to the smooth surface 12 of the copper foil as shown in FIG.

[0050] The mixture forming the adhesive layer 2 can be applied by various coating methods well known in the art, such as spray coating, curtain coating, knife-over-roll coating, air knife coating, slot die coating, casting, direct gravure, reverse gravure, offset gravure, roll coating, dip coating, or immersion coating. It should be noted that when dip coating or immersion coating is used, the resist side of the copper foil can be covered with a peelable protective layer. In some embodiments, slot die coating can be used.

[0051] Any suitable application method may be utilized to apply the resin mixture, as would be readily determined by one skilled in the art. As used herein, the term "coating" is not intended to limit the method by which it is applied onto the smooth side of the copper foil.

[0052] After coating, the solvent or solvent mixture can be removed by heating in an oven at temperatures ranging from 60 to 160°C to ensure the mixture is partially cured in the B-stage. The temperature and length of time in the oven will depend on the solvent used and the thickness of the coating layer. Alternatively, the composite material of the present invention can be produced by first coating a layer of the mixture onto a release liner or carrier film, and then transferring the coated layer to the smooth side of the copper foil by lamination.

[0053] The thickness of the adhesive layer of the composite material varies depending on the end use of the composite material. The adhesive layer of the composite material prior to lamination with a substrate has a thickness ranging from about 0.1 μm to about 200 μm, or from about 0.5 μm to about 100 μm, or from about 1 μm to about 50 μm, or from about 3 μm to about 20 μm. While such thicknesses are preferred, it should be understood that other thicknesses can be produced to meet specific needs and still fall within the scope of the present invention.

[0054] The composite generally has a total thickness of about 6.1 μm to about 600 μm, or about 10 μm to about 150 μm, or about 15 μm to about 100 μm, which can be adjusted according to the substrate type by varying the thickness of the adhesive layer, the thickness of the copper foil, or both.

[0055] Copper-clad laminate The composite material can be incorporated into a copper clad laminate (CCL) by laminating it onto a substrate. Suitable substrates for forming the CCL can be rigid or flexible.

[0056] Flexible substrates include, but are not limited to, polyimide (PI) films, polyamide-imide (PAI) films, liquid crystal polymer films, or fluorine-based polymer films. Commercially available polyimide films include Kapton® manufactured by DuPont and APICAL® manufactured by Kaneka. TM and UPILEX® manufactured by Ube; and polyamide-imide films such as Torlon® manufactured by Solvay.

[0057] Rigid substrates are typically derived from prepregs formed by impregnating fibrous reinforcing members with polymeric materials, examples of which include woven glass cloth such as E-glass (aluminosilicate glass) cloth, non-woven glass cloth, and non-woven aramid cloth.

[0058] Suitable polymeric materials for impregnation include, but are not limited to, epoxy resins, polyphenylene ethers (PPE), polyphenylene oxides (PPO), liquid crystal polymers (LCP), polyimides (PI), polyamideimides (PAI), polyetherimides (PEI), polyesters, polyolefins, poly(meth)acrylates, polyphenylene sulfides (PPS), polyoxymethylene (POM), polyaryletherketones (PAEK), polyetheretherketones (PEEK), polysulfones (PSU), polyethersulfones (PES), cyanate esters, polyethers or fluoropolymers.

[0059] Examples of epoxy resins include, but are not limited to, di- or multi-functional bisphenol A or bisphenol F resins, epoxy-novolac resins, or brominated epoxy resins.

[0060] Examples of polyesters include, but are not limited to, polybutylene terephthalate (PBT), polyethylene terephthalate (PET) or polyethylene naphthalate (PEN).

[0061] Examples of polyolefins include, but are not limited to, polypropylene (PP) or polyethylene (PE).

[0062] Examples of fluorine-based polymers include, but are not limited to, tetrafluoroethylene polymer (PTFE), tetrafluoroethylene hexafluoropropylene copolymer, tetrafluoroethylene perfluoro(alkyl vinyl ether) copolymer (PFA), tetrafluoroethylene ethylene copolymer, polychlorotrifluoroethylene, ethylene chlorotrifluoroethylene copolymer, polyvinylidene fluoride, vinyl fluoride hexafluoropropylene copolymer, or polyvinyl fluoride.

[0063] Examples of commercially available prepregs include 2929 bondply material (PTFE-based, Dk=2.9 and Df=0.3 at 10 GHz) and RO4450 available from Rogers Corp. TM Examples include prepreg (Dk = 3.30-3.54 at 10 GHz, depending on thickness); R-5670 prepreg material available from Panasonic Corp. (based on PPE, Dk = 3.35, Df = 0.004 at 12 GHz); and MCL-HS100 prepreg material available from Hitachi Chemical Co., Ltd. (based on epoxy resin, Dk = 3.4-4.1, Df = 0.0025-0.0055 at 10 GHz).

[0064] The composite material can be bonded onto one or both sides of a substrate depending on the application to form a single-sided CCL as shown in FIG. 2 or a double-sided CCL as shown in FIG.

[0065] As shown in FIG. 2, the composite material 100 of the present invention is placed on a substrate 3 with the adhesive layer 2 in contact with the substrate 3, and then laminated by methods such as hot pressing, continuous rolling, continuous belt pressing, etc. to provide a single-sided CCL, i.e., an embodiment of the present invention.

[0066] 3, a double-sided CCL 300 of the present invention may be fabricated by combining, in order, the present composite material 100, a substrate 3, an optional adhesive layer 4, and a second copper foil 5; and then laminating them together by the methods previously described, where the substrate 3 is in contact with the adhesive layer 2. Note that the second copper foil 5 and the copper foil 1 may be the same or different.

[0067] In some embodiments, when the adhesive layer 4 is absent, the second copper foil 5 of the double-sided CCL 300 of the present invention preferably has its roughened surface (i.e., also referred to herein as the lamination surface) in contact with the substrate 3 to ensure adequate bonding, and said roughened surface may be pre-treated with an adhesion promoter.

[0068] In some embodiments, adhesive layer 4 is present to enhance adhesion between second copper foil 5 and substrate 3, whether second copper foil 5 and copper foil 1 are the same or different.

[0069] In another embodiment, the adhesive layer 4 and the second copper foil 5 are derived from the composite material 110 of the present invention, where the composite material 110 and the composite material 100 can be the same or different.

[0070] The process parameters, such as temperature, pressure, and time, for preparing the present copper clad laminate generally depend on the material properties of the substrate and the preparation method, and those skilled in the art can determine suitable process parameters depending on the circumstances.

[0071] In some embodiments, the copper clad laminate is prepared by hot pressing.

[0072] In some embodiments, the hot pressing is carried out at a temperature ranging from about 80°C to about 250°C or from about 135°C to about 225°C; at a pressure ranging from about 0.2 MPa to about 17.4 MPa or from about 0.5 MPa to about 5 MPa; and for a duration of about 30 minutes to about 300 minutes or from about 60 minutes to about 240 minutes.

[0073] The copper clad laminates generally have a total thickness of about 30 μm to about 2000 μm, or about 50 μm to about 1500 μm, or about 90 μm to about 1000 μm, which can be easily adjusted by using composites and substrates of various thicknesses.

[0074] The present invention utilizes a composite material comprising a copper foil having at least one smooth surface, without roughening or pre-treatment with an adhesion promoter, and an adhesive layer composed of a low Dk and Df resin material to produce a copper clad laminate with good to excellent peel strength. The peel strength of this CCL can be, for example, 0.4 kN / m or more, or 0.6 kN / m or more, or 0.8 kN / m or more. It should be noted that peel strength data will vary due to possible variations in substrate. In this specification, peel strength is measured according to the method described in the Examples section below.

[0075] In addition, the copper clad laminate also has excellent heat resistance and is expected to withstand the soldering and reflow steps during the PCB manufacturing process. For example, the CCL can withstand heat treatment at 260°C, 288°C, or even 320°C or higher for at least 30 seconds without blistering or delamination of the specimen. In this specification, heat resistance to soldering temperatures is a value measured by the method described in the Examples section below.

[0076] Printed Circuit Board (PCB) The copper clad laminate of the present invention can be subjected to known patterning methods, such as subtractive (photolithography) or additive (electroplating) methods, to form a predetermined conductor pattern (i.e., circuitry) on the resist side of the copper foil to produce a printed circuit board (PCB or printed wiring board). Because PCB manufacturing methods are well known to those skilled in the art, disclosure thereof is omitted herein for the sake of brevity.

[0077] Printed circuit boards made from the composites and CCL can then be assembled with other components such as leads and air holes to form a variety of electrical articles utilizing high speed signals of at least 1 Gbps data rates and / or high frequency signals of at least 1 GHz.

[0078] A printed circuit board comprising the composite material of the present invention and a CCL has an insertion loss of 2.5 dB / 10 cm or less, or 2.0 dB / 10 cm or less, or 1.5 dB / 10 cm or less at a frequency of 10 GHz; and an insertion loss of 8.0 dB / 10 cm or less, or 7.0 dB / 10 cm or less, or 6.0 dB / 10 cm or less at a frequency of 39 GHz. As used herein, insertion loss is a value measured by the method described in the Examples section below.

[0079] Products that utilize high performance PCBs include servers, routers, storage area networks, power amplifiers, transceiver modules and high speed data channels.

[0080] In addition, consumer devices that require higher data transfer rates and computing power include portable electronic devices such as laptop computers, tablet computers, e-readers, portable gaming devices, portable media players, digital cameras, mobile phones or wearable devices; smart home devices; manned and unmanned vehicles; flying devices such as drones, airplanes and space equipment; and the like.

[0081] Without further elaboration, it is believed that one skilled in the art using the preceding description can utilize the present invention to its fullest extent. The following examples are, therefore, to be construed as merely illustrative and not limiting of the disclosure in any way whatsoever. [Example]

[0082] The abbreviation "E" stands for "Example" and "CE" stands for "Comparative Example" followed by a number indicating that a copper clad laminate was prepared in that example. The Examples and Comparative Examples were all prepared and tested in a similar manner.

[0083] raw materials CF1: Copper foil with a thickness of 12 μm; the smooth side of the foil has a surface roughness (Rz) of 0.62 μm and a surface roughness of 100 μg / dm 2Copper foil with the same grade as CF1 except for a thickness of 35 μm was tested and found to have a resistance of 0.170 gΩ / m 2 It was found to have the following electrical resistance: CF2: ED copper foil with a thickness of 35 μm; the smooth side of the foil has a surface roughness (Rz) of 1.06 μm and a surface roughness of 100 μg / dm 2 A piece of CF2 copper foil was tested and found to have a resistance of 0.170 gΩ / m 2 It was found to have the following electrical resistance: CF3: ED copper foil with a thickness of 12 μm, product number HVLP2; the laminate surface of the foil has a surface roughness (Rz) of 3.21 μm and a surface roughness of 300-350 μg / dm 2 Copper foil with the same grade as CF3 except for a thickness of 35 μm was tested and found to have a resistance of 0.170 gΩ / m 2 It was found to have the following electrical resistance: CF4: ED copper foil with a thickness of 12 μm, product number HVLP1; the laminate surface of the foil has a surface roughness (Rz) of 4.22 μm and a surface roughness of 350-400 μg / dm 2 Copper foil with the same grade as CF4 except for a thickness of 35 μm was tested and found to have a resistance of 0.170 gΩ / m 2 It was found to have the following electrical resistance: Adh1: Product name: Pyralux® GPL, a bonding sheet available from DuPont. A cured Adh1 sample was tested for Dk and Df according to the procedure described below and found to have a Dk of 2.8 and a Df of 0.0035. Adh2: A bonding sheet available from DuPont under the product name: Pyralux® GFL. A cured Adh2 sample was tested for Dk and Df according to the procedures described below and found to have a Dk of 2.4 and a Df of 0.0017. S1: An approximately 130 μm thick ultra-low loss planar prepreg constructed from woven glass fiber cloth and impregnated with a modified epoxy resin, with Dk=3.62 and Df=0.005 at 10 GHz (measured in accordance with the conditions specified by IPC-TM-650 No. 2.5.5.13). S2: A low-loss planar prepreg approximately 130 μm thick constructed from woven glass fiber cloth impregnated with modified epoxy resin, with Dk=3.9-4.0 and Df=0.005-0.006 at 1 GHz (tested in accordance with the conditions specified by IPC-TM-650 No. 2.5.5.9).

[0084] Preparation of Composites A and B Adh1 was transferred from a carrier film (132 μm release paper) to the smooth side of a piece of copper foil (CF1, 29 cm × 20 cm) by lamination using a roller laminator at a roller temperature of 120° C., approximately 0.3 MPa, and a line speed of 0.5 m / min to provide a piece of Composite A, i.e., one embodiment of the present invention. The resulting Composite A has a thickness of approximately 16.5 μm with an adhesive layer thickness of 4.5 μm.

[0085] Composite B was obtained following the procedure above, except that Adh2 was used to apply onto the smooth side of a piece of copper foil (CF2) replacing Adh1. The resulting Composite B has a thickness of approximately 39 μm with an adhesive layer thickness of 4 μm.

[0086] Preparation of Copper-Clad Laminates for Examples 1-3 The copper-clad laminates of Examples (E1-E3) had a configuration similar to that of the double-sided copper-clad laminate 300 in FIG. 3, except that optional layer 4 was absent. The CCLs were fabricated using a hot press (manufactured by LCM) as follows: a substrate sheet (S1 or S2) was cut into a 30 cm x 30 cm square sheet, and a composite (composite A or B) obtained by the above procedure was placed on the substrate with the adhesive layer in contact with the substrate. A piece of copper foil (CF3) was applied to the opposite side of the substrate with its lamination surface in direct contact with the substrate.

[0087] The deposition parameters were adjusted according to the recommended deposition parameters of the substrate. The deposition was carried out under reduced pressure of 0.99 atmospheres (751 Torr) with the following temperature and pressure profile: Temperature profile: (1) starting from 80°C, heated to 120°C within 5 minutes, (2) held at 120°C for 3 minutes, heated to 180°C within 5 minutes, (3) held at 180°C for 32 minutes, heated to 210°C within 5 minutes, (4) held at 210°C for 143 minutes, cooled to 160°C within 12 minutes, (5) cooled to 50°C within 1 minute, held at 50°C for 30 minutes. Pressure profile: (1) increased to 0.3 MPa within 1 min, (2) held at 0.3 MPa for 3 min and increased to 1.0 MPa within 1 min, (3) held at 1.0 MPa for 11 min and increased to 3.4 MPa within 1 min, (4) held at 3.4 MPa for 176 min and decreased to 2.7 MPa within 1 min, (5) held at 2.7 MPa for 11 min and decreased to 0.1 MPa within 1 min, (6) held at 0.1 MPa for 30 min.

[0088] Preparation of Copper-Clad Laminates of Comparative Examples 1 to 6 Each copper-clad laminate of Comparative Examples (CE1-6) was prepared by laminating a piece of copper foil (CF1, CF3, or CF4) directly to a substrate (S1 or S2) having a smooth surface, or with the laminating side of the copper foil in contact with the substrate. On the opposite side of the substrate, a piece of copper foil (CF3) was also laminated to the substrate with the laminating side in direct contact with the substrate. Lamination was performed according to the lamination conditions described above for Examples 1-3.

[0089] Preparation of test coupons for Examples 1 and 3 and Comparative Examples 1 to 6 Each copper clad laminate of the Examples and Comparative Examples was further processed to form microstrip structures with a total thickness of about 162 μm, a conductor length of 100 mm, a conductor thickness of 12 μm, and a conductor width of 300 μm for those CCLs using S1 as the substrate and 275 μm for the CCLs using S2 as the substrate, respectively.

[0090] The test results are listed in Tables 1-3.

[0091] Test Method Surface roughness (Rz): Measured at five points using a laser scanning microscope (manufactured by KEYENCE, model: VK-9700), and the data were averaged.

[0092] Layer thickness: The thickness of the adhesive layer of Composite A or B was measured by a contact thickness gauge. Each specimen was measured 6 to 10 times at different spots, and the results were averaged.

[0093] Electrical resistance test: According to IPC-TM-650 2.5.14, copper foil samples with a thickness of 35 μm were used, and the samples were annealed at 200° C. for 2 hours in a N 2 oven.

[0094] Solder Float Test: This test simulates the thermal shock encountered in the solder reflow component assembly process for printed circuit boards. Three specimens (size: 5 cm x 5 cm) per CCL were floated on a bath of molten solder (99.3% tin, 0.7% copper) by placing them CF3 side down at 260°C or 288°C for 3 minutes. The specimens were removed and then cooled to ambient temperature, and the specimens were visually inspected. The top surface of the specimen (i.e., the side opposite the CF3 side) was visually inspected, and a "pass" was indicated if no deterioration such as blistering or delamination was found.

[0095] Chemical Resistance and Aging Performance: Each CCL Example was subjected to a different chemical treatment. For the HCl resistance test, the specimen was immersed in a container with 18% HCl solution for 60 minutes, then removed from the container, rinsed with DI water, and air-dried at room temperature for 24 hours, and the appearance of the specimen was visually inspected. A similar procedure was repeated by exposing each specimen made from the corresponding CCL Example to other chemical treatments, such as 8% NaOH for 30 minutes and 3% H2SO4 at 50°C for 60 minutes. Finally, the specimens were placed in an oven at 180°C for 10 days. The specimens were then sent for peel strength testing to determine whether the chemical treatment or aging test caused any deterioration.

[0096] Peel strength test: CCL specimens, either as prepared or obtained after chemical treatment / aging tests, were cut into rectangular samples measuring 75 mm x 30 mm. The samples were then photolithographically patterned with straight lines at a line / space ratio of 1 mm / 1 mm. The patterned laminate sample was fixed onto a 98 mm (L) x 31 mm (W) FR4 plate (i.e., a fiberglass plate, purchased from HONTEC) with double-sided tape and then mounted on a sliding sample holder. The front part of the patterned laminate sample was then manually peeled off and fixed to the upper clamp. Peel strength was measured using a testing machine (manufactured by Shimadzu Corporation, Model: AG-IS) at a tensile speed of 50.8 mm / min, and the peel strength was measured and recorded in kN / m. The peel strength data for the three test lines were averaged and listed in Tables 1-2.

[0097] Dk / Df measurements: Adhesive samples (adh1 or adh2) were coated onto a peelable PET film at a thickness of approximately 25 μm, and then the adhesive layers were stacked to a thickness of approximately 85-125 μm and fully cured at 200°C for 90 minutes to produce cured adhesive samples. The cured adhesive samples were tested using a split-post dielectric resonator (SPDR) cavity and vector network analyzer (manufacturer: Keysight, model no. E5063A) at 10 GHz. Each sample was tested twice, and the two data sets were averaged to obtain Dk / Df data.

[0098] Insertion loss: The CCL specimens with microstrip structure without coverlay film were measured by a Keysight PNA Network Analyzer, scanning from 10 MHz to 40 GHz with a reference impedance of 50 Ω, a sweep number of 4001 points, calibration by Keysight AFR, and a temperature of 23°C. Among the measurements, the transmission loss (dB / m) corresponding to the frequencies at 10 GHz and 39 GHz was reported in Table 3. The improvement in insertion loss was calculated by dividing the difference between the insertion loss data of the comparative example and the measured insertion loss data of the reference example by the data of the comparative example.

[0099] [Table 1]

[0100] The results in Table 1 make the following clear:

[0101] Comparison between the data for E1 and E2 versus the data for CE1 demonstrated that the CCLs in E1 and E2 demonstrated better heat resistance and maintained high peel strength through various acid / base treatments.

[0102] Comparing the data for E1 to those for CE2 and CE3, which have the same substrate (i.e., S1) and copper foil thickness, the laminate for E1 demonstrated similar heat resistance, peel strength, and maintained peel strength through various acid / base treatments. These results indicate that the composites and CCLs of the present invention are suitable for providing PCBs with excellent performance and reliability even after multiple harsh conditions throughout the manufacturing process.

[0103] [Table 2]

[0104] The results in Table 2 make the following clear:

[0105] Comparison of the solder float data of E3 versus that of CE4 unexpectedly demonstrated that the CCL of E3 also performed better in terms of heat resistance and peel strength through various acid / base treatment and aging tests. These results indicate that the composite is compatible with various substrates and that the CCL of the present invention can provide PCBs with superior performance and reliability even at high operating temperatures.

[0106] [Table 3]

[0107] The results in Table 3 make the following clear:

[0108] In a comparison between the insertion loss data of E1 versus that of CE2 and CE3 when they have the same substrate, the CCL of E1 surprisingly provided lower insertion loss values ​​than those of the CCLs of CE2 and CE3.

[0109] A comparison between the insertion loss data of E3 versus that of CE5 and CE6 when they have the same substrate also shows that the CCL of E3 provides a significantly lower insertion loss value than that of the CCLs of CE5 and CE6. The results demonstrate that the present composites and CCLs are suitable for producing low insertion loss printed circuit boards for high frequency or high speed circuit applications.

[0110] While the present invention has been illustrated and described in exemplary embodiments, it is not intended to be limited to the details shown, since various modifications and substitutions are possible without departing from the spirit of the invention. Accordingly, modifications and equivalents of the invention disclosed herein may occur to those skilled in the art using no more than routine experimentation, and all such modifications and equivalents are deemed to be within the spirit and scope of the invention as defined by the following claims.

Claims

1. A copper clad laminate comprising a substrate and a composite, the substrate is a prepreg composed of a fibrous reinforcing member impregnated with a polymer material; the fibrous reinforcing member is a woven glass cloth, a nonwoven glass cloth, or a nonwoven aramid cloth; and the polymer material is an epoxy resin, polyphenylene ether, polyphenylene oxide, a liquid crystal polymer, polyimide, polyamideimide, polyetherimide, polyester, polyolefin, poly(meth)acrylate, polyphenylene sulfide, polyoxymethylene, polyaryletherketone, polyetheretherketone, polysulfone, polyethersulfone, cyanate ester, polyether, or a fluorine-based polymer; the composite includes a copper foil and an adhesive layer; The copper foil has a resistivity of 0.170 gΩ / m 2 Electrical resistance of less than 2.0 μm, surface roughness (Rz) of less than 0.1 particles / μm 2 at least one smooth surface having a nodule density of less than 350 μg / dm 2 and a passivation layer having the following total content of non-copper metallic elements: the adhesive layer is derived from a mixture including a resin matrix containing 5 to 25 parts by weight of a reactive resin, 0.1 to 3 parts by weight of a curing agent, and 72 to 94.9 parts by weight of a styrene-based rubber, the reactive resin being an epoxy resin, and the styrene-based rubber being an acid-modified styrene-based rubber; the adhesive layer is in contact with the smooth surface of the copper foil via the passivation layer; The adhesive layer cured with the curing agent at 200°C for 90 minutes has a Dk of 3.0 or less and a Df of 0.006 or less at 10 GHz according to IPC-TM-650 No. 2.5.5.13; and A copper clad laminate, provided that said smooth surface of said copper foil has not been pretreated with an adhesion promoter.

2. 10. The copper clad laminate of claim 1, wherein the mixture further comprises an additive, the additive being selected from the group consisting of adhesion promoters, antioxidants, antistatic agents, colorants, fillers, flame retardants, impact modifiers, lubricants, processing aids, heat stabilizers, and UV absorbers.

3. The copper clad laminate of claim 2, wherein the amount of the additive is greater than 0 to 100 parts by weight based on 100 parts by weight of the resin matrix.

4. The copper clad laminate of claim 1, wherein the copper foil has a thickness of 6 μm to 400 μm.

5. The copper clad laminate of claim 1, wherein the adhesive layer has a thickness of 0.1 μm to 200 μm.

6. 10. The copper clad laminate of claim 1, wherein the as-prepared copper clad laminate has a peel strength between the substrate and the composite of 0.4 kN / m or greater.

7. 10. The copper clad laminate of claim 1, wherein the as-conditioned copper clad laminate has a heat resistance at 260°C for more than 30 seconds.

8. 10. The copper clad laminate of claim 1, wherein the as-tuned copper clad laminate has an insertion loss of 2.5 dB / 10 cm or less at 10 GHz or 8.0 dB / 10 cm or less at 39 GHz.

9. A printed circuit board manufactured from the copper clad laminate of claim 8.

10. 10. Use of the printed circuit board of claim 9 in high speed applications, high frequency applications, or both, wherein the data rate of the high speed applications is greater than 1 Gbps and the frequency of the high frequency applications is greater than 1 GHz.

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