Composite substrate and method for manufacturing the same

Abstract

The present disclosure provides a composite substrate and a manufacturing method thereof. The composite substrate includes a first fluoropolymer layer, a liquid crystal polymer layer, and a second fluoropolymer layer. The liquid crystal polymer layer is fused to an upper surface of the first fluoropolymer layer. The second fluoropolymer layer is fused to an upper surface of the liquid crystal polymer layer. The first fluoropolymer layer and the second fluoropolymer layer independently include 30 to 50 parts by weight of a fluoropolymer, 1 to 5 parts by weight of a dispersant, 1 to 10 parts by weight of a plurality of inorganic particles, and 1 to 5 parts by weight of a polymer resin, wherein the polymer resin is different from the fluoropolymer. The surfaces of the fluoropolymer layer and the liquid crystal polymer layer can be fused to each other by a heating process without surface treatment and / or without adhesive layer coating to have good adhesive strength.

Description

Technical Field

[0001] This disclosure relates to a composite substrate and its manufacturing method. Background Technology

[0002] With the development of communication technology, various types of printed circuit boards (PCBs) have been developed to improve signal transmission speed and reduce production costs. PCBs are indispensable components in electronic products, and the demand for PCBs is increasing daily with the growing demand for consumer electronics. For example, flexible PCBs, due to their flexibility, are widely used in communication products and consumer electronics. However, to further meet the requirements of communication technology regarding the dielectric constant, loss coefficient, and other parameters of PCBs, a new substrate and its manufacturing method are needed. Summary of the Invention

[0003] This disclosure provides a composite substrate comprising: a first fluoropolymer layer, a liquid crystal polymer layer, and a second fluoropolymer layer. The liquid crystal polymer layer is fused to the upper surface of the first fluoropolymer layer. The second fluoropolymer layer is fused to the upper surface of the liquid crystal polymer layer. The first and second fluoropolymer layers independently comprise: 30 to 50 parts by weight of a fluoropolymer, 1 to 5 parts by weight of a dispersant, 1 to 10 parts by weight of a plurality of inorganic particles, and 1 to 5 parts by weight of a polymeric resin, wherein the polymeric resin is different from the fluoropolymer.

[0004] In some embodiments, the fluoropolymer includes polytetrafluoroethylene (PTFE), ethylene-tetrafluoroethylene copolymer (ETFEcopolymer), tetrafluoroethene-hexafluoropropene copolymer, tetrafluoroethylene-perfluoroalkylvinyl ether copolymer, polychlorotrifluoroethylene (PCTFE), ethylene-trifluorochloroethylene copolymer (ECTFE copolymer), trifluorochloroethylene-tetrafluoroethene copolymer, polyvinylidene difluoride (PVDF), tetrafluoroethene-hexafluoropropene-difluoroethylene copolymer, tetrafluoroethene-perfluoroalkoxyvinyl ether copolymer, or combinations thereof.

[0005] In some embodiments, the inorganic particles include titanium dioxide, silicon dioxide, aluminum oxide, zirconium dioxide, magnesium oxide, calcium oxide, talc, aluminum hydroxide, magnesium hydroxide, barium sulfate, calcium carbonate, potassium titanate, clay, or combinations thereof.

[0006] In some embodiments, the dispersant includes ethyl acetate, butyl acetate, ethylene glycol ethyl ether acetate, phthalate, propylene glycol methyl ether acetate, urethane, tripropylene glycol diacrylate, 1,6-ethylene glycol diacrylate, propylene glycol monomethyl ether ester, ethylene glycol methyl ether acetate, methoxyethyl acetate, ethyl acrylate, fatty acid polyethylene glycol ester, vinyl formate, methacrylate, or combinations thereof.

[0007] In some embodiments, the polymeric resin includes poly(acrylic acid), PAA, polyimide, liquid crystal polymer, cyclic olefin polymer, cyclic olefin copolymer, styrene-butadiene copolymer, styrene-ethylene copolymer, styrene-propylene copolymer, styrene-butene copolymer, polyester, polyolefin, polyphenylene ether, polyphenylene sulfide, styrene, polycarbonate, polyarylate, maleic anhydride resin, polysulfone, polyarylsulfone, polyaryl ether ketone, epoxy resin, polyvinyl acetate, polyolefin, polyarylamide, polyetheretherketone (PEEK), poly(ether sulfone), PES, polyphenylene oxide (PPO), polyacetal, polyetherimide, polysiloxane, or combinations thereof.

[0008] This disclosure provides a method for manufacturing a composite substrate, comprising the following operations: A first fluoropolymer layer, a liquid crystal polymer layer, and a second fluoropolymer layer are sequentially stacked from bottom to top. The first and second fluoropolymer layers independently comprise: 30 to 50 parts by weight of a fluoropolymer, 1 to 5 parts by weight of a dispersant, 1 to 10 parts by weight of a plurality of inorganic particles, and 1 to 5 parts by weight of a polymeric resin, wherein the polymeric resin is different from the fluoropolymer. A heating process is performed to fuse the first fluoropolymer layer, the liquid crystal polymer layer, and the second fluoropolymer layer, wherein the heating process temperature is 200°C to 400°C or the glass transition temperature of the fluoropolymer to the melting point of the fluoropolymer + 40°C.

[0009] In some embodiments, the first fluoropolymer layer and the second fluoropolymer layer further include 30 to 60 parts by weight of solvent and are respectively dispersion liquid layers, and the liquid crystal polymer layer is a solid film or adhesive layer.

[0010] In some embodiments, the solvent includes N-methyl-2-pyrrolidone (NMP), methyl ethyl ketone (MEK), N,N-dimethylacetamide (DMAC), or combinations thereof.

[0011] In some embodiments, the first fluoropolymer layer, the second fluoropolymer layer, and the liquid crystal polymer layer are all solid thin films.

[0012] In some embodiments, the method further includes placing the first fluoropolymer layer, the liquid crystal polymer layer, and the second fluoropolymer layer in a nitrogen oven or an infrared oven during the heating process.

[0013] In some embodiments, the method further includes: performing a pressurization process while performing the heating process, wherein the pressure of the pressurization process is 1 kg / cm². 2 Up to 100kg / cm 2 .

[0014] In some implementations, the heating time of the heating process is from 1 minute to 300 minutes.

[0015] In some embodiments, the method further includes: hot-pressing a composite substrate and a metal substrate.

[0016] In some embodiments, the method further includes: sequentially stacking a first fluoropolymer layer, a liquid crystal polymer layer, and a second fluoropolymer layer on a metal substrate from bottom to top, and performing a heating process to fuse the first fluoropolymer layer and the metal substrate.

[0017] In some embodiments, the method further includes the following steps: Before sequentially stacking the first fluoropolymer layer, the liquid crystal polymer layer, and the second fluoropolymer layer from bottom to top, a first liquid crystal polymer adhesive layer is applied to cover the upper surface of the first fluoropolymer layer. A second liquid crystal polymer adhesive layer is applied to cover the lower surface of the second fluoropolymer layer. The first and second liquid crystal polymer adhesive layers are cured to form a first portion and a second portion of the liquid crystal polymer layer, respectively.

[0018] In some embodiments, the method further includes the following steps: Before sequentially stacking the first fluoropolymer layer, the liquid crystal polymer layer, and the second fluoropolymer layer from bottom to top, a liquid crystal polymer adhesive layer is applied to cover the lower surface of the second fluoropolymer layer. The liquid crystal polymer adhesive layer is then cured to form the liquid crystal polymer layer. Attached Figure Description

[0019] This disclosure can be more fully understood by reading the following detailed description of the embodiments and referring to the accompanying drawings.

[0020] Figure 1 This is a schematic cross-sectional view of a composite substrate according to various embodiments of the present disclosure;

[0021] Figure 2 This is a flowchart of a method for manufacturing a composite substrate according to various embodiments of the present disclosure;

[0022] Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 , Figure 8 , Figure 9 , Figure 10 , Figure 11 and Figure 12These are cross-sectional schematic diagrams of intermediate stages in the manufacture of composite substrates according to various embodiments of this disclosure.

[0023] Figure 13 This is a schematic diagram of the composite substrate used in Experimental Example 1;

[0024] Figure 14 This is a schematic cross-sectional view of the composite substrate in Experiment Example 2.

[0025] [Symbol Explanation]

[0026] 100, 700, 800, 900, 920, 1000, 1020, 1100, 1130, 1200, 1210, 1300, 1400, 1410: Composite substrate

[0027] 110, 310, 410, 510, 610, 710, 810, 922, 1022, 1022', 1132, 1214, 1310, 1310', 1414: First fluoropolymer layer

[0028] 120, 320, 420, 520, 620, 720, 820, 924, 1024, 1024', 1134, 1216, 1320, 1320', 1416: Liquid crystal polymer layer

[0029] 130, 330, 430, 530, 630, 730, 830, 926, 1026, 1026', 1136, 1218, 1330, 1330', 1418: Second fluoropolymer layer

[0030] 200: Method

[0031] 210, 220: Operation

[0032] 910, 1010: Metal substrate

[0033] 1110, 1220: First metal substrate

[0034] 1120, 1212: Second metal substrate

[0035] 1420, 1412: Copper foil substrate

[0036] LP1: First liquid crystal polymer adhesive layer

[0037] LP2: Second liquid crystal polymer adhesive layer

[0038] LP3: Liquid crystal polymer adhesive layer

[0039] P1: Part 1

[0040] P2: Part Two

[0041] S1, S2, S3: Upper surface

[0042] S4, S5: Lower surface Detailed Implementation

[0043] The following embodiments are described and disclosed in detail with reference to the accompanying drawings. For clarity, many practical details will be set forth in the following description. However, it should be understood that these practical details are not intended to limit the scope of this disclosure. That is, these practical details are not essential in some embodiments of this disclosure. Furthermore, for the sake of simplicity, some known structures and elements will be illustrated schematically in the drawings.

[0044] This disclosure provides a composite substrate and its manufacturing method. The composite substrate includes two fluoropolymer layers and a liquid crystal polymer layer, wherein the liquid crystal polymer layer is sandwiched between the fluoropolymer layers. The surfaces of the fluoropolymer layers and the liquid crystal polymer layer can be fused together by a heating process without surface treatment and / or without adhesive layer coating, and the peel strength between the interfaces can be, for example, greater than or equal to 1 kgf / cm. This composite substrate can be used as a high-frequency high-speed substrate, a substrate for flexible circuit boards, an interposer for tape-ball grid arrays (TBGAs), an interposer for chip-scale packages (CSPs), or a carrier film / adhesive film for tape-and-reel bonding technology. The composite substrate of this disclosure can have a low dielectric constant, a low loss coefficient, a low coefficient of thermal expansion, a low water absorption rate, and good adhesion strength.

[0045] This disclosure provides a composite substrate 100. Figure 1 This is a schematic cross-sectional view of a composite substrate 100 according to various embodiments of the present disclosure. The composite substrate 100 includes a first fluoropolymer layer 110, a liquid crystal polymer layer 120, and a second fluoropolymer layer 130. The liquid crystal polymer layer 120 is fused to the upper surface S1 of the first fluoropolymer layer 110. The second fluoropolymer layer 130 is fused to the upper surface S2 of the liquid crystal polymer layer 120. In some embodiments, the thicknesses of the first fluoropolymer layer 110, the liquid crystal polymer layer 120, and the second fluoropolymer layer 130 are independently from 1 μm to 150 μm, for example, 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, or 150 μm.

[0046] In some embodiments, the surfaces of the first fluoropolymer layer 110, the liquid crystal polymer layer 120, and the second fluoropolymer layer 130 do not require surface treatment before welding. In some embodiments, no adhesive layer (e.g., low-dielectric adhesive) needs to be provided between the first fluoropolymer layer 110, the liquid crystal polymer layer 120, and the second fluoropolymer layer 130. Therefore, the fluoropolymer at least provides the advantage of being able to directly heat-fuse with the liquid crystal polymer layer 120. Furthermore, when at least one metal substrate (e.g., copper foil, aluminum foil, gold foil, or a combination thereof) is further disposed on the lower surface of the first fluoropolymer layer 110 and / or the upper surface of the second fluoropolymer layer 130, the surfaces of the first fluoropolymer layer 110 and the second fluoropolymer layer 130 do not require surface treatment, nor is it necessary to provide any adhesive layer (e.g., low-dielectric adhesive) between the metal substrate and the fluoropolymer layer. A heating process can be used to achieve good adhesion strength at the interface between the metal substrate and the fluoropolymer layer, with a peel strength, for example, greater than or equal to 1 kgf / cm. Since no additional adhesive layer or surface treatment is required during the formation of the composite substrate 100, it is advantageous to thin the composite substrate 100 and simplify the process. Because no adhesive layer is required, the problem of adhesive hardening during secondary coating is avoided. Based on the above, the manufacturing method disclosed herein can produce the composite substrate 100 through a simple process, which helps to reduce manufacturing costs.

[0047] In some embodiments, the first fluoropolymer layer 110 and the second fluoropolymer layer 130 are solid films and independently comprise: 30 to 50 parts by weight of a fluoropolymer, 1 to 5 parts by weight of a dispersant, 1 to 10 parts by weight of a plurality of inorganic particles, and 1 to 5 parts by weight of a polymeric resin. The above materials are mixed together. The polymeric resin is different from the fluoropolymer. More specifically, the polymeric resin and the fluoropolymer are different materials with different monomer unit structures. For example, the polymeric resin is fluorine-free. The content of the fluoropolymer, dispersant, inorganic particles, and polymeric resin can be any positive integer within the above numerical range. For example, the fluoropolymer is 30, 35, 40, 45, or 50 parts by weight, the dispersant is 1, 2, 3, 4, or 5 parts by weight, the inorganic particles are 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 parts by weight, and the polymeric resin is 1, 2, 3, 4, or 5 parts by weight. When the contents of the fluoropolymer, dispersant, inorganic particles, and polymer resin fall within the aforementioned numerical range, the first fluoropolymer layer 110, the liquid crystal polymer layer 120, and the second fluoropolymer layer 130 can have good adhesion strength, and the composite substrate 100 can have a low dielectric constant, a low loss coefficient, and a low coefficient of thermal expansion (CTE). In some embodiments, the dielectric constant (Dk) of the composite substrate 100 at 10 GHz is 2.0 to 3.0, for example, 2.0, 2.4, 2.6, 2.8, or 3.0. In some embodiments, the loss coefficient (Df) of the composite substrate 100 at 10 GHz is 0.0004 to 0.02, for example, 0.0004, 0.0006, 0.0008, 0.001, 0.005, 0.01, 0.015, or 0.02. In some embodiments, the CTE of the composite substrate 100 is from 5 ppm / °C to 40 ppm / °C, for example, 5, 10, 15, 20, 25, 30, 35, or 40 ppm / °C. Because the CTE of the composite substrate 100 is similar to that of metals, the composite substrate 100 is less prone to warping when a metal substrate is attached to its surface. In some embodiments, the water absorption rate of the composite substrate 100 is less than or equal to 0.04%. Because the composite substrate 100 can have a low water absorption rate, it exhibits excellent stability and is suitable for use in high-frequency circuit boards or high-speed transmission line circuits.

[0048] The first fluoropolymer layer 110 and the second fluoropolymer layer 130 can be formed by curing a fluoropolymer dispersion or by cutting a fluoropolymer solid film. In some embodiments, the fluoropolymer dispersion used to form the first fluoropolymer layer 110 and the second fluoropolymer layer 130 independently comprises: 30 to 50 parts by weight of a fluoropolymer, 1 to 5 parts by weight of a dispersant, 1 to 10 parts by weight of a plurality of inorganic particles, 1 to 5 parts by weight of a polymeric resin, and 30 to 60 parts by weight of a solvent. The weight parts of the fluoropolymer, dispersant, inorganic particles, polymeric resin, and solvent can be any positive integer within the above-mentioned numerical range. For example, the solvent is 30, 35, 40, 45, 50, 55, or 60 parts by weight. In some embodiments, the solvent includes N-methylpyrrolidone (NMP), methyl ethyl ketone (MEK), N,N-dimethylacetamide (DMAC), or combinations thereof. The above solvent can uniformly mix the fluoropolymer, dispersant, inorganic particles, and polymeric resin.

[0049] In some embodiments, the fluoropolymer includes polytetrafluoroethylene (PTFE), ethylene-tetrafluoroethylene copolymer (ETFE copolymer), tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, polychlorotrifluoroethylene (PCTFE), ethylene-chlorotrifluoroethylene copolymer (ECTFE copolymer), chlorotrifluoroethylene-tetrafluoroethylene copolymer, polyvinylidene fluoride (PVDF), tetrafluoroethylene-hexafluoropropylene-difluoroethylene copolymer, tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer, or combinations thereof. Tetrafluoroethylene-perfluoroalkyl vinyl ether copolymers include, for example, tetrafluoroethylene-perfluoroethyl vinyl ether copolymers, tetrafluoroethylene-perfluoron-propyl vinyl ether copolymers, or combinations thereof. In some embodiments, in the tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, the alkyl group of the perfluoroalkyl vinyl ether is linear or branched, and is, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, dibutyl, tributyl, or pentyl. In some embodiments, the tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer is polymerized from a single perfluoroalkyl vinyl ether and tetrafluoroethylene, wherein the perfluoroalkyl vinyl ether can be from 1 wt% to 15 wt%, for example 1, 2, 4, 6, 8, 10, 12, 14, or 15 wt%. In some embodiments, the tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer is polymerized from a variety of different perfluoroalkyl vinyl ethers and tetrafluoroethylene, such as perfluoromethyl vinyl ether and perfluoropropyl vinyl ether. In the reactants used to synthesize the copolymer, the perfluoromethyl vinyl ether can be from 0.5 wt% to 13 wt%, and the perfluoropropyl vinyl ether can be from 0.5 wt% to 3 wt%. The above-mentioned fluoropolymers at least have the effect of being able to bond tightly to the liquid crystal polymer layer and / or metal substrate at high temperatures. Furthermore, when the composite substrate 100 is used as a circuit board, it may be necessary to form multiple holes in the composite substrate 100 by ultraviolet laser drilling and fill the holes with conductive material. Compared to fluorine-free polymers, fluoropolymers absorb ultraviolet light more easily, thus making it easier to form conductive elements in the composite substrate 100 through ultraviolet laser drilling.

[0050] In some embodiments, the inorganic particles include titanium dioxide, silicon dioxide, aluminum oxide, zirconium dioxide, magnesium oxide, calcium oxide, talc, aluminum hydroxide, magnesium hydroxide, barium sulfate, calcium carbonate, potassium titanate, clay, or combinations thereof. In some embodiments, the average particle size of the inorganic particles is from 0.1 μm to 20 μm, for example, 0.1, 0.5, 1, 2, 4, 6, 8, 10, 12, 14, 16, 18, or 20 μm. The inorganic particles can reduce the coefficient of thermal expansion (CTE) of the first fluoropolymer layer 110 and the second fluoropolymer layer 130, thereby preventing warping of the composite substrate 100. In some embodiments, the CTE of the first fluoropolymer layer 110 and the second fluoropolymer layer 130 is from 5 ppm / °C to 40 ppm / °C, for example, 5, 10, 15, 20, 25, 30, 35, or 40 ppm / °C.

[0051] In some embodiments, the dispersant includes ethyl acetate, butyl acetate, ethylene glycol ethyl ether acetate, phthalate, propylene glycol methyl ether acetate, urethane, tripropylene glycol diacrylate, 1,6-ethylene glycol diacrylate, propylene glycol monomethyl ether ester, ethylene glycol methyl ether acetate, methoxyethyl acetate, ethyl acrylate, fatty acid polyethylene glycol ester, vinyl formate, methacrylate, or combinations thereof. The methacrylate may be methyl methacrylate. The above dispersants can improve the dispersibility of inorganic particles, thereby uniformly dispersing the inorganic particles in the first fluoropolymer layer 110 and / or the second fluoropolymer layer 130, to uniformly reduce the CTE of the first fluoropolymer layer 110 and the second fluoropolymer layer 130.

[0052] In some embodiments, the polymeric resin includes polyacrylic acid, polyimide, liquid crystal polymer, cyclic olefin polymer, cyclic olefin copolymer, styrene-butadiene copolymer, styrene-ethylene copolymer, styrene-propylene copolymer, styrene-butene copolymer, polyester, polyolefin, polyphenylene ether, polyphenylene sulfide, styrene, polycarbonate, polyarylate, maleic anhydride resin, polysulfone, polyarylsulfone, polyaryletherketone, epoxy resin, polyvinyl acetate, polyolefin, polyarylamide, polyetheretherketone, polyethersulfone, polyoxyxylene, polyacetal, polyetherimide, polysiloxane, or combinations thereof. In some embodiments, the weight-average molecular weight of the polymeric resin is between 10,000 and 500,000, for example, 10,000, 20,000, 40,000, 60,000, 80,000, 100,000, 200,000, 300,000, 400,000, or 500,000. When the first fluoropolymer layer 110 and / or the second fluoropolymer layer 130 contain PAA and / or polyimide, when the composite substrate 100 is used as a circuit board, the PAA and / or polyimide easily absorb UV lasers, thereby making it easy to form drill holes in the composite substrate 100 by laser drilling, so as to facilitate the formation of conductive lines in the composite substrate 100.

[0053] The liquid crystal polymer layer 120 can be formed by curing a liquid crystal polymer adhesive layer, or by forming a thin film from the liquid crystal polymer through injection molding or extrusion molding. In some embodiments, the liquid crystal polymer adhesive layer includes a soluble liquid crystal polymer, an aromatic polymer, and a solvent. The solvent in the liquid crystal polymer adhesive layer can be substantially removed after curing. The liquid crystal polymer adhesive layer can be coated at temperatures ranging from 40°C to 160°C, for example, 40, 60, 80, 100, 120, 140, or 160°C. Compared to thin films formed from insoluble liquid crystal polymers, the liquid crystal polymer layer 120 formed from a liquid crystal polymer adhesive layer reduces processing time and equipment costs, and this liquid crystal polymer layer 120 is less prone to peeling or cracking due to external stress. Furthermore, the liquid crystal polymer adhesive layer has high plasticity, so a flat surface can be easily formed during the manufacturing process of the liquid crystal polymer layer 120, thereby reducing the possibility of subsequent circuit formation being damaged by adhesion, compression, or other issues due to uneven surfaces. In some embodiments, the soluble liquid crystal polymer comprises a plurality of monomer units, wherein the monomer units have a structure as shown in formula (1):

[0054]

[0055] Ar is 1,4-phenylene, 1,3-phenylene, 2,6-naphthalene, or 4,4′-biphenylene; Y is O or NH; Z is C=O; X is NH, amide, imino, amido, aminocarbonylamino, aminothiocarbonyl, aminocarbonyloxy, aminosulfonyl, aminosulfonyloxy, aminosulfonylamino, carboxyl ester, (carboxyl ester)amino, (alkoxycarbonyl)oxy, alkoxycarbonyl, hydroxyamino, alkoxyamino, cyanato, isocyanato, or a combination thereof. In some embodiments, the aromatic polymer includes aromatic polyesters, aromatic polyamides, poly(p-phenylene terephthalamide), poly(p-phenylenebenzodioxazole), copolymers of p-hydroxybenzoic acid and 6-hydroxy-2-naphthyl acid, or combinations thereof. In some embodiments, the solvent includes N-methyl-2-pyrrolidone, N,N-dimethylacetamide, γ-butyrolactone, dimethylformamide, 2-butoxyethanol, 2-ethoxyethanol, or combinations thereof.

[0056] In some embodiments, the liquid crystal polymer adhesive layer comprises liquid crystal polymer powder and a solvent. In some embodiments, the liquid crystal polymer powder comprises a thermotropic liquid crystal polymer resin. In some embodiments, the curing temperature of the liquid crystal polymer adhesive layer is at least higher than the liquid crystal transition temperature of the thermotropic liquid crystal polymer resin. The thermotropic liquid crystal polymer resin may be a high-heat-resistant liquid crystal polymer resin with a liquid crystal transition temperature greater than 330°C, a medium-heat-resistant liquid crystal polymer resin with a liquid crystal transition temperature of 280°C to 320°C, or a low-heat-resistant liquid crystal polymer resin with a liquid crystal transition temperature less than 240°C. For example, the high-heat-resistant liquid crystal polymer resin may be polymerized from p-hydroxybenzoic acid, terephthalic acid, and 4,4'-dioxybiphenol. For example, the medium-heat-resistant liquid crystal polymer resin may be polymerized from p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid. For example, the low-heat-resistant liquid crystal polymer resin may be polymerized from polyterephthalic acid and p-hydroxybenzoic acid. In some embodiments, the average particle size of the liquid crystal polymer powder is from 1 nm to 1000 μm, for example, 1 nm, 5 nm, 10 nm, 15 nm, 20 nm, 30 nm, 50 nm, 70 nm, 90 nm, 100 nm, 1 μm, 5 μm, 10 μm, 15 μm, 20 μm, 50 μm, 100 μm, 200 μm, 300 μm, 400 μm, 500 μm, 600 μm, 700 μm, 800 μm, 900 μm, or 1000 μm. Liquid crystal polymer powders having the above-mentioned average particle size can exhibit good dispersibility in solvents. In some embodiments, the solvent includes amides, acids, alcohols, ketones, aromatic solvents, water, or combinations thereof. In some embodiments, the amide comprises N,N-dimethylacetamide, hexamethylphosphoric triamine, N-methylpyrrolidone, N,N,N',N'-tetramethylurea, methylcaprolactam, N-acetylpyrrolidone, N,N-dimethylpropionamide, N-methylpiperidinone, 1,3-dimethyl-2-imidazolinone, N,N,N',N'-tetramethylmalonamide, dimethylformamide, or combinations thereof. In some embodiments, the acid comprises sulfuric acid, hydrofluoric acid, trifluoromethanesulfonic acid, trifluoroacetic acid, a mixed solution of trifluoroacetic acid / dichloromethane, a mixed solution of trifluoroacetic acid / dichloromethane / tetrachloroethylene, chlorosulfonic acid, or combinations thereof. In some embodiments, the alcohol comprises hexafluoroisopropanol. In some embodiments, the aromatic solvent includes toluene, xylene, p-chlorophenol, a mixture of p-chlorophenol and tetrachloroethane, a mixture of o-dichlorobenzene and p-chlorophenol, a mixture of phenol, tetrachloroethane, and p-chlorophenol, a mixture of phenol and tetrachloroethane, a mixture of phenol and chloroform, cresol, o-chlorophenol, pentafluorophenol, p-fluorophenol, or combinations thereof.In some embodiments, the weight ratio of liquid crystal polymer powder to solvent (liquid crystal polymer powder / solvent) is from 1:100 to 90:100, for example, 1:100, 10:100, 20:100, 30:100, 40:100, 50:100, 60:100, 70:100, 80:100, and 90:100. When the weight ratio falls within the above range, the liquid crystal polymer powder can be uniformly dispersed in the solvent.

[0057] In some embodiments, the liquid crystal polymer layer 120 is formed by injection molding or extrusion molding to produce a thin film from the liquid crystal polymer. In some embodiments, the liquid crystal polymer is polymerized from a reactant composition. The reactant composition includes a plurality of first monomers, a plurality of second monomers, a plurality of third monomers, a plurality of fourth monomers, or combinations thereof. The first monomer is an aromatic dicarboxylic acid, an aliphatic dicarboxylic acid, or a combination thereof; the second monomer is an aromatic hydroxycarboxylic acid; the third monomer is an aromatic diol, an aliphatic diol, or a combination thereof; and the fourth monomer is an aromatic diamine, an aromatic hydroxyamine, an aromatic aminocarboxylic acid, or a combination thereof. For example, the first monomer includes... HOOC(CH2) n COOH (n is an integer from 2 to 12) or combinations thereof, but not limited to these. A1 is a halogen group or an alkyl group, such as a fluoro group, chloro group, bromo group, or iodo group, and such as a methyl group, ethyl group, n-propyl group, or isopropyl group. For example, the second monomer includes Or combinations thereof, but not limited to. A2 is a halogen group or an alkyl group, such as a fluorinated, chloro, bromine, or iodo group, and such as a methyl, ethyl, n-propyl, or isopropyl group. For example, the third monomer includes HO(CH2) n OH (n is an integer from 2 to 12) or combinations thereof, but not limited to these. A3 and A4 are independently halogenated or alkyl groups, and A5 is H, a halogenated or alkyl group. Halogenated groups are, for example, fluoro, chloro, bromo, or iodo groups, and alkyl groups are, for example, methyl, ethyl, n-propyl, or isopropyl. For example, the fourth monomer includes... Or combinations thereof, but not limited thereto. In some embodiments, the liquid crystal polymer comprises the following monomer units: In some embodiments, the liquid crystal polymer includes the following monomer units:

[0058] In some embodiments, the liquid crystal polymer includes the following monomer units: In some embodiments, the liquid crystal polymer includes the following monomer units: In some embodiments, the liquid crystal polymer includes the following monomer units:

[0059] In some embodiments, the liquid crystal polymer includes the following monomer units: And *-OCH2CH2O-*.

[0060] This disclosure provides a method for manufacturing a composite substrate. Figure 2 This is a flowchart of a method 200 for manufacturing a composite substrate according to various embodiments of the present disclosure. The method includes operations 210 and 220. Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 , Figure 8 , Figure 9 , Figure 10 , Figure 11 and Figure 12 These are cross-sectional schematic diagrams illustrating intermediate stages in the fabrication of composite substrates according to various embodiments of this disclosure. Although the methods disclosed herein are described below using a series of operations or steps, the order in which these operations or steps are shown should not be construed as a limitation of this disclosure. For example, some operations or steps may be performed in a different order and / or simultaneously with other steps. Furthermore, not all illustrated operations, steps, and / or features are required to achieve the embodiments of this disclosure. Additionally, each operation or step described herein may comprise several sub-steps or actions.

[0061] Please refer to the following at the same time Figure 2 and Figure 3In operation 210, a first fluoropolymer layer 310, a liquid crystal polymer layer 320, and a second fluoropolymer layer 330 are stacked sequentially from bottom to top. The first fluoropolymer layer 310 and the second fluoropolymer layer 330 are dispersion layers, and the liquid crystal polymer layer 320 is an adhesive layer. More specifically, the first fluoropolymer dispersion, the liquid crystal polymer adhesive, and the second fluoropolymer dispersion can be simultaneously extruded by an extruder with three openings to simultaneously coat and form the first fluoropolymer layer 310, the liquid crystal polymer layer 320, and the second fluoropolymer layer 330. The first fluoropolymer layer 310 and the second fluoropolymer layer 330 independently comprise: 30 to 50 parts by weight of fluoropolymer, 1 to 5 parts by weight of dispersant, 1 to 10 parts by weight of a plurality of inorganic particles, 1 to 5 parts by weight of polymer resin, and 30 to 60 parts by weight of solvent. In some embodiments, the solvent includes N-methylpyrrolidone (NMP), methyl ethyl ketone (MEK), N,N-dimethylacetamide (DMAC), or combinations thereof. The materials and properties of the fluoropolymers, dispersants, inorganic particles, and polymer resins in the first fluoropolymer layer 310 and the second fluoropolymer layer 330 are the same as those in the first fluoropolymer layer 110 and the second fluoropolymer layer 130, and therefore will not be repeated. In some embodiments, the liquid crystal polymer layer 320 includes a soluble liquid crystal polymer, an aromatic polymer, and a solvent. In other embodiments, the liquid crystal polymer layer 320 includes liquid crystal polymer powder and a solvent. In operation 220, a heating process is performed to fuse the first fluoropolymer layer 310, the liquid crystal polymer layer 320, and the second fluoropolymer layer 330, thereby forming... Figure 1 The composite substrate 100 is shown. In some embodiments, the heating process temperature is from 200°C to 400°C, for example, 200, 220, 240, 260, 280, 300, 320, 340, 360, 380, or 400°C. In some embodiments, the heating process temperature is the glass transition temperature (Tg) of the fluoropolymer. g ) to the melting point (T) of fluoropolymers m +40℃, for example, T m T m +10, T m +20, T m +30 or T m +40℃. In some embodiments, the heating time of the heating process is from 1 minute to 300 minutes, for example, 1, 5, 10, 20, 30, 40, 50, 100, 150, 200, 250, or 300 minutes. Within the above temperature range and heating time range, the first fluoropolymer layer 310, the liquid crystal polymer layer 320, and the second fluoropolymer layer 330 can have good adhesion strength, and the peel strength of these films can be, for example, greater than or equal to 1 kgf / cm. Therefore, through... Figure 3 The composite substrate 100 prepared according to the illustrated embodiment can serve as a high-frequency, high-speed substrate. More specifically, after performing the heating process, the solvent within the first fluoropolymer layer 310, the liquid crystal polymer layer 320, and the second fluoropolymer layer 330 can be substantially removed, allowing these layers to dry and form a composite substrate. Figure 1 The solid film shown.

[0062] Please refer to the following at the same time Figure 2 and Figure 4 In operation 210, a first fluoropolymer layer 410, a liquid crystal polymer layer 420, and a second fluoropolymer layer 430 are stacked sequentially from bottom to top. The first fluoropolymer layer 410 and the second fluoropolymer layer 430 are dispersion liquid layers, and the liquid crystal polymer layer 420 is a solid film. More specifically, the first fluoropolymer dispersion and the second fluoropolymer dispersion can be applied to the upper and lower surfaces of the liquid crystal polymer layer 420, respectively, to form the first fluoropolymer layer 410 and the second fluoropolymer layer 430. The formation method, materials, thickness, and function of the liquid crystal polymer layer 420 are related to... Figure 1 The liquid crystal polymer layer 120 is formed in the same way, with the same materials, thickness, and function. The first fluoropolymer layer 410 and the second fluoropolymer layer 430 are formed in the same way, with the same materials, and function. Figure 3 The formation methods, materials, and functions of the first fluoropolymer layer 310 and the second fluoropolymer layer 330 are the same, and therefore will not be described again. In operation 220, a heating process is performed to fuse the first fluoropolymer layer 410, the liquid crystal polymer layer 420, and the second fluoropolymer layer 430, thereby forming as shown in the figure. Figure 1 The composite substrate 100 is shown. The temperature, time, and effectiveness of this heating process are related to... Figure 3 The heating process of the implementation method is the same in terms of temperature, time and effect, so it will not be described again.

[0063] Please refer to the following at the same time Figure 2 and Figure 5 In operation 210, a first fluoropolymer layer 510, a liquid crystal polymer layer 520, and a second fluoropolymer layer 530 are stacked sequentially from bottom to top. The liquid crystal polymer layer 520, the first fluoropolymer layer 510, and the second fluoropolymer layer 530 are all solid films, and therefore substantially solvent-free. The formation method, materials, thickness, and functions of the liquid crystal polymer layer 520, the first fluoropolymer layer 510, and the second fluoropolymer layer 530 are... Figure 1 The liquid crystal polymer layer 120, the first fluoropolymer layer 110, and the second fluoropolymer layer 130 are formed using the same methods, materials, thicknesses, and functions, and therefore will not be described again. In operation 220, a heating process is performed to fuse the first fluoropolymer layer 510, the liquid crystal polymer layer 520, and the second fluoropolymer layer 530, thereby forming the liquid crystal polymer layer 510, the liquid crystal polymer layer 520, and the second fluoropolymer layer 530. Figure 1The composite substrate 100 is shown. The temperature, time, and effectiveness of this heating process are related to... Figure 3 The heating process in the implementation method has the same temperature, time, and effect, so it will not be described again. Furthermore, in Figure 5 In the embodiment shown, during the heating process, a pressurization process is performed to hot-press the first fluoropolymer layer 510, the liquid crystal polymer layer 520, and the second fluoropolymer layer 530, wherein the pressure of the pressurization process is 1 kg / cm². 2 Up to 100kg / cm 2 For example, 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90 or 100 kg / cm² 2 When the pressure falls within the aforementioned range, the first fluoropolymer layer 510, the liquid crystal polymer layer 520, and the second fluoropolymer layer 530 can exhibit good adhesion strength, for example, a peel strength greater than or equal to 1 kgf / cm. When both heating and pressurizing processes are performed simultaneously, the temperature required for welding can be reduced.

[0064] Please refer to the following at the same time Figure 2 and Figure 6 In operation 210, a first fluoropolymer layer 610, a liquid crystal polymer layer 620, and a second fluoropolymer layer 630 are stacked sequentially from bottom to top. The liquid crystal polymer layer 620, the first fluoropolymer layer 610, and the second fluoropolymer layer 630 are all solid films, and therefore substantially solvent-free. The formation method, materials, thickness, and functions of the liquid crystal polymer layer 620, the first fluoropolymer layer 610, and the second fluoropolymer layer 630 are... Figure 1 The liquid crystal polymer layer 120, the first fluoropolymer layer 110, and the second fluoropolymer layer 130 are formed using the same methods, materials, thicknesses, and functions, and therefore will not be described again. In operation 220, a heating process is performed to fuse the first fluoropolymer layer 610, the liquid crystal polymer layer 620, and the second fluoropolymer layer 630, thereby forming a liquid crystal polymer layer 610, the liquid crystal polymer layer 620, and the second fluoropolymer layer 630. Figure 1 The composite substrate 100 is shown. The temperature, time, and effectiveness of this heating process are related to... Figure 3 The heating process in the implementation method has the same temperature, time, and effect, so it will not be described again. Figure 6 In the illustrated embodiments, during the heating process, no additional pressure is applied to the first fluoropolymer layer 610, the liquid crystal polymer layer 620, and the second fluoropolymer layer 630. Instead, the first fluoropolymer layer 610, the liquid crystal polymer layer 620, and the second fluoropolymer layer 630 are fused together at high temperature. In some embodiments, the method further includes placing the first fluoropolymer layer 610, the liquid crystal polymer layer 620, and the second fluoropolymer layer 630 in a nitrogen oven or an infrared oven during the heating process, thereby improving the efficiency and yield of the fusion process.

[0065] Please refer to the following at the same time Figure 2 and Figure 7 In operation 210, a first fluoropolymer layer 710, a liquid crystal polymer layer 720, and a second fluoropolymer layer 730 are stacked sequentially from bottom to top. In operation 220, a heating process is performed to fuse the first fluoropolymer layer 710, the liquid crystal polymer layer 720, and the second fluoropolymer layer 730, thereby forming a composite substrate 700. The temperature, time, and effectiveness of this heating process are related to... Figure 3 The heating process in the embodiments described herein has the same temperature, time, and effect, and therefore will not be repeated. In some embodiments, reference may be made to... Figure 5 In this embodiment, a pressure process is performed to heat-press the first fluoropolymer layer 710, the liquid crystal polymer layer 720, and the second fluoropolymer layer 730. Before stacking the first fluoropolymer layer 710, the liquid crystal polymer layer 720, and the second fluoropolymer layer 730 sequentially from bottom to top, a first liquid crystal polymer adhesive layer LP1 is applied to cover the upper surface S3 of the first fluoropolymer layer 710, and a second liquid crystal polymer adhesive layer LP2 is applied to cover the lower surface S4 of the second fluoropolymer layer 730. The first liquid crystal polymer adhesive layer LP1 and the second liquid crystal polymer adhesive layer LP2 are cured to form the first portion P1 and the second portion P2 of the liquid crystal polymer layer 720, respectively. The first portion P1 and the second portion P2 of the liquid crystal polymer layer 720 are brought into contact with each other, and a heating process is performed to fuse the first fluoropolymer layer 710, the liquid crystal polymer layer 720, and the second fluoropolymer layer 730, wherein the first portion P1 and the second portion P2 are fused together. The materials of the first liquid crystal polymer adhesive layer LP1 and the second liquid crystal polymer adhesive layer LP2 are the same as those used in the liquid crystal polymer adhesive layer for manufacturing the liquid crystal polymer layer 120, so they will not be described again.

[0066] Please refer to the following at the same time Figure 2 and Figure 8 In operation 210, a first fluoropolymer layer 810, a liquid crystal polymer layer 820, and a second fluoropolymer layer 830 are stacked sequentially from bottom to top. In operation 220, a heating process is performed to fuse the first fluoropolymer layer 810, the liquid crystal polymer layer 820, and the second fluoropolymer layer 830, thereby forming a composite substrate 800. The temperature, time, and effectiveness of this heating process are related to... Figure 3 The heating process in the embodiments described herein has the same temperature, time, and effect, and therefore will not be repeated. In some embodiments, reference may be made to... Figure 5In this embodiment, a pressure process is performed to heat-press the first fluoropolymer layer 810, the liquid crystal polymer layer 820, and the second fluoropolymer layer 830. Before stacking the first fluoropolymer layer 810, the liquid crystal polymer layer 820, and the second fluoropolymer layer 830 sequentially from bottom to top, a liquid crystal polymer adhesive layer LP3 is applied to cover the lower surface S5 of the second fluoropolymer layer 830. The liquid crystal polymer adhesive layer LP3 is cured to form the liquid crystal polymer layer 820. The liquid crystal polymer layer 820 is brought into contact with the first fluoropolymer layer 810, and a heating process is performed to fuse the first fluoropolymer layer 810, the liquid crystal polymer layer 820, and the second fluoropolymer layer 830. The material of the liquid crystal polymer adhesive layer LP3 is the same as the material of the liquid crystal polymer adhesive layer used to manufacture the liquid crystal polymer layer 120, and therefore will not be described again.

[0067] Please refer to Figure 9 The composite substrate 900 includes a metal substrate 910 and a composite substrate 920 fused together. The composite substrate 920 includes a first fluoropolymer layer 922, a liquid crystal polymer layer 924, and a second fluoropolymer layer 926 stacked sequentially from bottom to top. (Refer to the foregoing.) Figures 3 to 8 The composite substrate 920 is manufactured according to any embodiment. In some embodiments, the method of manufacturing the composite substrate 900 includes performing a heating process to fuse the metal substrate 920 and the composite substrate 920. In some embodiments, the temperature of the heating process is from 200°C to 400°C, for example, 200, 220, 240, 260, 280, 300, 320, 340, 360, 380, or 400°C. In some embodiments, the temperature of the heating process is the glass transition temperature (T0) of the fluoropolymer. g ) to the melting point (T) of fluoropolymers m +40℃, for example, T m T m +10, T m +20, T m +30 or T m +40°C. In some embodiments, the heating time of the heating process is from 1 minute to 300 minutes, for example, 1, 5, 10, 20, 30, 40, 50, 100, 150, 200, 250, or 300 minutes. Within the above temperature range, the composite substrate 920 and the metal substrate 910 can have good adhesion strength, and the peel strength of these films can be, for example, greater than or equal to 1 kgf / cm. In some embodiments, during the heating process, a pressure process is performed to hot-press the metal substrate 910 and the composite substrate 920, wherein the pressure of the pressure process is 1 kg / cm. 2 Up to 100kg / cm 2 For example, 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90 or 100 kg / cm² 2When the pressure falls within the aforementioned range, the metal substrate 910 and the composite substrate 920 can exhibit good adhesion strength, and the peel strength of these films can be, for example, greater than or equal to 1 kgf / cm. In some embodiments, the method of manufacturing the composite substrate 900 includes: sequentially stacking a first fluoropolymer layer 922, a liquid crystal polymer layer 924, and a second fluoropolymer layer 926 from bottom to top on the metal substrate 910, and performing a heating process to fuse the metal substrate 910, the first fluoropolymer layer 922, the liquid crystal polymer layer 924, and the second fluoropolymer layer 926. In some embodiments, the first fluoropolymer layer 922, the liquid crystal polymer layer 924, and the second fluoropolymer layer 926 are all solid thin films. In some embodiments, the thickness of the metal substrate 910 is from 1 μm to 72 μm, for example, 1, 5, 10, 20, 30, 40, 50, 60, 70, or 72 μm. In some embodiments, the metal substrate 910 comprises copper, aluminum, iron, silver, palladium, nickel, chromium, molybdenum, tungsten, zinc, chromium, manganese, cobalt, gold, tin, lead, stainless steel, or alloys of the above metals. In some embodiments, the metal substrate 910 is copper foil, such as electrolytic copper foil or rolled copper foil.

[0068] Please refer to Figure 10 The composite substrate 1000 includes a metal substrate 1010 and a composite substrate 1020 fused together. The composite substrate 1020 includes a first fluoropolymer layer 1022', a liquid crystal polymer layer 1024', and a second fluoropolymer layer 1026' stacked sequentially from bottom to top. In some embodiments, the material and structure of the metal substrate 1010 are the same as those of the metal substrate 910, and will not be described again. The method for manufacturing the composite substrate 1000 includes: stacking the first fluoropolymer layer 1022, the liquid crystal polymer layer 1024, and the second fluoropolymer layer 1026 sequentially from bottom to top on the metal substrate 1010. The first fluoropolymer layer 1022 and the second fluoropolymer layer 1026 are dispersion liquid layers, and the liquid crystal polymer layer 1024 is an adhesive layer. Next, a heating process is performed to fuse the metal substrate 1010, the first fluoropolymer layer 1022, the liquid crystal polymer layer 1024, and the second fluoropolymer layer 1026 to form the composite substrate 1000. The temperature, time, pressure, and effectiveness of this heating process are related to... Figure 9 The heating process of the implementation method is the same in terms of temperature, time, pressure and effect, so it will not be described again.

[0069] Please refer to Figure 11The composite substrate 1100 includes a first metal substrate 1110, a second metal substrate 1120, and a composite substrate 1130 fused together. The composite substrate 1130 includes a first fluoropolymer layer 1132, a liquid crystal polymer layer 1134, and a second fluoropolymer layer 1136 stacked sequentially from bottom to top. In some embodiments, the materials and structures of the first metal substrate 1110 and the second metal substrate 1120 are the same as those of the metal substrate 910, and will not be described again. Refer to the foregoing... Figures 3 to 8 The composite substrate 1130 is manufactured according to any embodiment. The method for manufacturing the composite substrate 1100 includes: sequentially stacking a first metal substrate 1110, a composite substrate 1130, and a second metal substrate 1120 from bottom to top; performing a heating process to fuse the first metal substrate 1110, the composite substrate 1130, and the second metal substrate 1120 to form the composite substrate 1100. The temperature, time, pressure, and efficiency of this heating process are similar to... Figure 9 The heating process of the implementation method is the same in terms of temperature, time, pressure and effect, so it will not be described again.

[0070] Please refer to Figure 12 The composite substrate 1200 includes a composite substrate 1210 and a first metal substrate 1220 fused together. See the foregoing. Figures 9 to 10 The composite substrate 1210 is manufactured according to any embodiment. The composite substrate 1210 includes a second metal substrate 1212, a first fluoropolymer layer 1214, a liquid crystal polymer layer 1216, and a second fluoropolymer layer 1218 stacked sequentially from bottom to top. In some embodiments, the materials and structures of the first metal substrate 1220 and the second metal substrate 1212 are the same as those of the metal substrate 910, and will not be described again. The method for manufacturing the composite substrate 1100 includes: stacking the composite substrate 1210 and the first metal substrate 1220 sequentially from bottom to top; performing a heating process to fuse the first metal substrate 1220 and the composite substrate 1210. The temperature, time, pressure, and efficiency of this heating process are the same as those of the first metal substrate 1220 and the composite substrate 1210. Figure 9 The heating process of the implementation method is the same in terms of temperature, time, pressure and effect, so it will not be described again.

[0071] The features of this disclosure will be described in more detail below with reference to Experimental Examples 1 and 2. Although the following embodiments are described, the materials used, their quantities and ratios, processing details, and processing procedures may be appropriately changed without departing from the scope of this disclosure. Therefore, this disclosure should not be interpreted restrictively based on the embodiments described below.

[0072] Experimental Example 1: Fabrication of Composite Substrates and Measurement of Their Properties

[0073] Figure 13This is a schematic diagram of the composite substrate 1300 used in Experimental Example 1. A first fluoropolymer layer 1310, a liquid crystal polymer layer 1320, and a second fluoropolymer layer 1330 are stacked sequentially from bottom to top. The first fluoropolymer layer 1310 and the second fluoropolymer layer 1330 are dispersion layers, each comprising: tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, ethyl acetate, silica particles, polyacrylic acid, and N-methylpyrrolidone. The liquid crystal polymer layer 1320 is a solid film with a melting point of 300°C to 350°C and a CTE of 18 ppm / °C to 22 ppm / °C. More specifically, the first fluoropolymer dispersion and the second fluoropolymer dispersion can be applied to the upper and lower surfaces of the liquid crystal polymer layer 1320, respectively, to form the first fluoropolymer layer 1310 and the second fluoropolymer layer 1330. A heating process is performed to fuse the first fluoropolymer layer 1310, the liquid crystal polymer layer 1320, and the second fluoropolymer layer 1330, thereby removing the solvent from the first fluoropolymer layer 1310 and the second fluoropolymer layer 1330, thus forming a composite substrate 1300. The composite substrate 1300 includes a first fluoropolymer layer 1310', a liquid crystal polymer layer 1320', and a second fluoropolymer layer 1330' fused sequentially from bottom to top. The manufacturing conditions and property test results of the composite substrates 1300 of Examples 1 to 8 are shown in Table 1 below. As can be seen from Table 1, the composite substrates 1300 of Examples 1 to 8 can have a peel strength of 1 kgf / cm to 1.3 kgf / cm, a dielectric constant (Dk) of 2.4 to 3.0, and a loss factor (Df) of 0.0026 to 0.0035, and are therefore suitable as high-frequency and high-speed substrates.

[0074] Table 1

[0075]

[0076] Experimental Example 2: Fabrication of Composite Substrates and Measurement of Their Properties

[0077] Figure 14This is a cross-sectional schematic diagram of the composite substrate 1400 in Example 2. The manufacturing method of the composite substrate 1400 includes: sequentially stacking a composite substrate 1410 and a copper foil substrate 1420 from bottom to top; performing a heating process to fuse the composite substrate 1410 and the copper foil substrate 1420. The composite substrate 1410 includes a copper foil substrate 1412, a first fluoropolymer layer 1414, a liquid crystal polymer layer 1416, and a second fluoropolymer layer 1418, sequentially stacked from bottom to top. The thicknesses of the copper foil substrate 1412 and the copper foil substrate 1420 are both 12 μm. The first fluoropolymer layer 1414, the liquid crystal polymer layer 1416, and the second fluoropolymer layer 1418 are solid thin films. The first fluoropolymer layer 1414 and the second fluoropolymer layer 1418 respectively comprise: tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, silica particles, and polyacrylic acid. The liquid crystal polymer layer 1416 is a solid thin film with a melting point of 300°C to 350°C and a CTE of 18 ppm / °C to 22 ppm / °C. The manufacturing conditions and property test results of the composite substrates 1400 in Examples 9 and 10 are shown in Table 2 below. As can be seen from Table 2, the composite substrates 1400 in Examples 9 to 16 have a peel strength of 1.0 kgf / cm to 1.4 kgf / cm, a dielectric constant (Dk) of 2.4 to 3.0, and a loss factor (Df) of 0.0026 to 0.0029, thus making them suitable as high-frequency, high-speed substrates.

[0078] Table 2

[0079]

[0080] In summary, this disclosure provides a composite substrate and a method for manufacturing the same. The composite substrate of this disclosure can possess low dielectric constant, low loss coefficient, low coefficient of thermal expansion, low water absorption, and good adhesion strength. The manufacturing method of this disclosure allows for the fabrication of the composite substrate through a simple process, which helps to reduce manufacturing costs.

[0081] Although this disclosure has been described in considerable detail with reference to certain embodiments, other embodiments may also be possible. Therefore, the spirit and scope of the appended claims should not be limited to the description of the embodiments contained herein.

[0082] It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of this disclosure without departing from its scope or spirit. In view of the foregoing, this disclosure is intended to cover any modifications and variations falling within the scope of the appended claims.

Claims

1. A composite substrate, characterized in that, include: A first fluoropolymer layer; A liquid crystal polymer layer is fused to an upper surface of the first fluoropolymer layer; and A second fluoropolymer layer is fused to an upper surface of the liquid crystal polymer layer, wherein the first fluoropolymer layer and the second fluoropolymer layer independently comprise: 30 to 50 parts by weight of a monofluoropolymer; 1 to 5 parts by weight of a dispersant; Multiple inorganic particles, ranging from 1 part by weight to 10 parts by weight; as well as One to five parts by weight of a polymeric resin, wherein the polymeric resin is different from the fluoropolymer.

2. The composite substrate as described in claim 1, characterized in that, The fluoropolymer includes polytetrafluoroethylene, ethylene-tetrafluoroethylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, polychlorotrifluoroethylene, ethylene-trifluorochloroethylene copolymer, trifluorochloroethylene-tetrafluoroethylene copolymer, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene-difluoroethylene copolymer, tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer, or combinations thereof.

3. The composite substrate as described in claim 1, characterized in that, These inorganic particles include titanium dioxide, silicon dioxide, aluminum oxide, zirconium dioxide, magnesium oxide, calcium oxide, talc, aluminum hydroxide, magnesium hydroxide, barium sulfate, calcium carbonate, potassium titanate, clay, or combinations thereof.

4. The composite substrate as described in claim 1, characterized in that, The dispersant includes ethyl acetate, butyl acetate, ethylene glycol ethyl ether acetate, phthalate, propylene glycol methyl ether acetate, acrylate, tripropylene glycol diacrylate, 1,6-ethylene glycol diacrylate, propylene glycol monomethyl ether ester, ethylene glycol methyl ether acetate, methoxyethyl acetate, ethyl acrylate, fatty acid polyethylene glycol ester, vinyl formate, methacrylate, or combinations thereof.

5. The composite substrate as described in claim 1, characterized in that, The polymer resin includes polyacrylic acid, polyimide, liquid crystal polymer, cyclic olefin polymer, cyclic olefin copolymer, styrene-butadiene copolymer, styrene-ethylene copolymer, styrene-propylene copolymer, styrene-butene copolymer, polyester, polyolefin, polyphenylene ether, polyphenylene sulfide, styrene, polycarbonate, polyarylate, maleic anhydride resin, polysulfone, polyarylsulfone, polyaryl ether ketone, epoxy resin, polyvinyl acetate, polyolefin, polyarylamide, polyether ether ketone, polyethersulfone, polyoxymethylene, polyacetal, polyetherimide, polysiloxane, or combinations thereof.

6. A method for manufacturing a composite substrate, characterized in that, include: A first fluoropolymer layer, a liquid crystal polymer layer, and a second fluoropolymer layer are stacked sequentially from bottom to top, wherein the first fluoropolymer layer and the second fluoropolymer layer independently comprise: 30 to 50 parts by weight of a monofluoropolymer; 1 to 5 parts by weight of a dispersant; Multiple inorganic particles, ranging from 1 part by weight to 10 parts by weight; as well as One to five parts by weight of a polymeric resin, wherein the polymeric resin is different from the fluoropolymer; and A heating process is performed to fuse the first fluoropolymer layer, the liquid crystal polymer layer, and the second fluoropolymer layer, wherein a temperature of the heating process is 200°C to 400°C or the glass transition temperature of the fluoropolymer to the melting point of the fluoropolymer + 40°C.

7. The method as described in claim 6, characterized in that, The first fluoropolymer layer and the second fluoropolymer layer further include 30 to 60 parts by weight of a solvent, which are each a dispersion layer, and the liquid crystal polymer layer is a solid film or an adhesive layer.

8. The method as described in claim 7, characterized in that, The solvent includes N-methylpyrrolidone, methyl ethyl ketone, N,N-dimethylacetamide, or combinations thereof.

9. The method as described in claim 6, characterized in that, The first fluoropolymer layer, the second fluoropolymer layer, and the liquid crystal polymer layer are each a solid thin film.

10. The method as described in claim 9, characterized in that, Also includes: During the heating process, the first fluoropolymer layer, the liquid crystal polymer layer, and the second fluoropolymer layer are placed in a nitrogen oven or an infrared oven.

11. The method as described in claim 9, characterized in that, Also includes: During the heating process, a pressurization process is performed, wherein the pressure of the pressurization process is 1 kg / cm². 2 Up to 100kg / cm 2 .

12. The method as described in claim 6, characterized in that, The heating time for this heating process ranges from 1 minute to 300 minutes.

13. The method as described in claim 6, characterized in that, Also includes: The composite substrate and a metal substrate are hot-pressed together.

14. The method as described in claim 6, characterized in that, Also includes: The first fluoropolymer layer, the liquid crystal polymer layer, and the second fluoropolymer layer are stacked sequentially from bottom to top on a metal substrate; The heating process is performed to fuse the first fluoropolymer layer and the metal substrate.

15. The method as described in claim 6, characterized in that, Also includes: Before stacking the first fluoropolymer layer, the liquid crystal polymer layer, and the second fluoropolymer layer sequentially from bottom to top. A first liquid crystal polymer adhesive layer is applied to cover an upper surface of the first fluoropolymer layer; A second liquid crystal polymer adhesive layer is applied to cover a lower surface of the second fluoropolymer layer; and The first liquid crystal polymer adhesive layer and the second liquid crystal polymer adhesive layer are cured to form a first portion and a second portion of the liquid crystal polymer layer, respectively.

16. The method as described in claim 6, characterized in that, Also includes: Before stacking the first fluoropolymer layer, the liquid crystal polymer layer, and the second fluoropolymer layer sequentially from bottom to top. A liquid crystal polymer adhesive layer is applied to cover a lower surface of the second fluoropolymer layer; and The liquid crystal polymer adhesive layer is cured to form the liquid crystal polymer layer.

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