TWI696024B - Flexible resin coated copper foil substrate and methods thereof - Google Patents

Abstract

The present invention provides a flexible resin coated copper foil substrate and methods thereof. The flexible resin coated copper foil substrate comprises an upper dielectric layer, a lower dielectric layer, a core layer which is formed between the upper dielectric layer and a lower dielectric layer and comprises liquid crystal polymer and filled powder dispersed in the liquid crystal polymer, and a copper foil layer formed on the upper dielectric layer. The upper dielectric layer being disposed between the core layer and the copper foil substrate. The present invention provides a flexible resin coated copper foil substrate possessing the advantage of low water-absorbent, low coefficient of thermal expansion, high adhesive strength, low dielectric loss etc., and is suitable for high-frequency and high-speed flexible substrate.

Description

Flexible glue-coated copper foil substrate and manufacturing method thereof

The invention relates to a flexible printed circuit (FPC) using a flexible resin coated copper (FRCC) substrate and a manufacturing technology field thereof, in particular to a flexible adhesive coated copper foil substrate.

With the increase in demand for high-frequency high-speed transmission and the advent of the 5G era, the demand for high-performance engineering plastics has increased significantly. In the past, flexible copper foil substrates were made of copper foil and polyimide (PI) resin and other raw materials, but polyimide The amine film has a high dielectric constant, is easy to absorb moisture, and is likely to cause signal loss under high-frequency and high-speed transmission. Liquid crystal polymer (LCP) materials have the characteristics of low moisture absorption, high chemical resistance, high dimensional stability, low dielectric constant and low dielectric loss factor (Dk/Df). The low water absorption in microwave and high-frequency millimeter waves has obvious advantages over traditional polyimide films, and it has gradually become a new application material, which can be applied to antennas, base stations, millimeter wave radars, etc.

At present, the liquid crystal polymer substrate products manufactured by the coating method on the market have high water absorption rate and thermal expansion coefficient. High water absorption rate (0.5 to 0.6%) may occur in the downstream application stage of downstream manufacturers, and the liquid crystal polymer layer may The high expansion coefficient (30 to 35 ppm/°C) and copper foil (17 to 18 ppm/°C) do not match, and curling may occur. In addition, compared with polyimide, the liquid crystal has a high score The bonding force between the sub and the copper foil is poor, so the liquid crystal polymer substrate usually uses a copper foil with a rougher surface and a higher Rz value to improve the bonding strength. However, in the skin effect of high-frequency and high-speed transmission, the electron transmission tends to proceed on the surface of the copper foil. If the surface of the copper foil is rough, a large signal loss will be formed, so how to reduce the water absorption of the liquid crystal polymer The rate and thermal expansion coefficient and how to improve the bonding strength of the liquid crystal polymer layer and the copper foil layer, so that the copper foil with a lower Rz value can be used when manufacturing the substrate is an important issue in the development of liquid crystal polymer substrates.

In order to meet the market demand for high-frequency and high-speed flexible sheets, the present invention provides a flexible rubber-coated copper foil substrate, which has low water absorption rate, low thermal expansion coefficient, high adhesion strength, low dielectric constant, low dielectric loss, High-speed transmission and good mechanical properties are especially suitable for 5G smart phones, smart watches, wristbands and other wearable devices.

In order to solve the above technical problems, the present invention provides a flexible rubber-coated copper foil substrate, which includes: a core layer having opposing first and second surfaces, which includes a liquid crystal polymer and a filler powder dispersed in the liquid crystal polymer A body; a dielectric adhesive layer and a lower dielectric adhesive layer respectively formed on the first surface and the second surface of the core layer; and a copper foil layer formed on the upper dielectric adhesive layer to make the upper intermediary The glue layer is located between the core layer and the copper foil layer.

In an embodiment, the surface roughness Rz of the copper foil layer in contact with the upper dielectric adhesive layer is 0 to 1.2 μm, the surface roughness Ra is 0 to 0.04 μm, and the copper foil layer is rolled copper Foil layer or electrolytic copper foil layer.

In an embodiment, the thickness of the core layer is 12 to 75 μm; the thickness of the upper dielectric layer is 1 to 10 μm; the thickness of the lower dielectric layer is 15 to 50 μm; and the copper The thickness of the foil layer is 1 to 35 μm.

In an embodiment, the core layer has two core layers or three core layers.

In an embodiment, the upper dielectric layer and the lower dielectric layer have a Dk value of 2.0 to 4.0 and a Df value of 0.001 to 0.010.

In a specific embodiment, the upper dielectric layer and the lower dielectric layer independently include at least one of component A and component B, and the component A is selected from ceramic powder, sintered dioxide At least one of the group consisting of silicon, Teflon, fluorine resins other than Teflon, polyetheretherketone and flame retardants, the component B is selected from epoxy resins, acrylic resins, amine groups At least one of the group consisting of formate resin, silicone rubber resin, parylene resin, bismaleimide resin and polyimide resin.

In a specific embodiment, the component A accounts for more than 0 to 50% by weight of the total solid content of any of the upper and lower dielectric adhesive layers, and the component B accounts for the The total solid content of any one of the upper dielectric adhesive layer and the lower dielectric adhesive layer is 5 to 80% by weight.

In an embodiment, the Dk value of the core layer is 2.5 to 4.0, and the Df value is 0.001 to 0.010.

In a specific embodiment, the filled powder system includes at least one of a group consisting of a first filled powder, a second filled powder, and a third filled powder. The first filled powder system is selected from silicon dioxide, At least one of the group consisting of quartz, titanium dioxide, aluminum oxide, zinc oxide, zirconium oxide, magnesium oxide, and aluminum hydroxide; the second filler powder system is selected from calcium carbonate, aluminum carbonate, Magnesium carbonate, calcium silicate, magnesium silicate, aluminum silicate, calcium aluminum silicate, calcium magnesium silicate, barium sulfate, talc, clay, kaolin, mica, calcite, wollastonite and dolomite powder At least one; the third filling powder system is at least one selected from the group consisting of silicon carbide, boron carbide, boron nitride, polyetheretherketone, and Teflon.

In a specific embodiment, the first filled powder system accounts for 20 to 70% by weight of the total solid content of the core layer, and the second filled powder system accounts for 10 to 30% by weight of the total solid content of the core layer. The third filled powder system accounts for 0 to 30% by weight of the total solid content of the core layer.

In another embodiment of the present invention, the flexible glued copper foil substrate further includes a release layer formed on the lower dielectric adhesive layer so that the lower dielectric adhesive layer is located on the core layer and the release Between layers.

The invention further provides a method for preparing a flexible glue-coated copper foil substrate, which includes the following steps: forming the upper dielectric glue layer on the copper foil layer; forming the core layer on the upper dielectric glue layer to form flexibility Semi-finished products of glued copper foil substrates; tempering the semi-finished products of flexible glued copper foil substrates; and forming a lower dielectric adhesive layer on the core layer of the semi-finished products of flexible glued copper foil substrates tempered so that the core layer is located Between the upper dielectric adhesive layer and the lower dielectric adhesive layer.

In another embodiment of the present invention, in the step of forming the upper dielectric paste layer, the solvent in the upper dielectric paste layer is removed at 60 to 180°C.

In another embodiment of the present invention, in the step of forming the core layer, the solvent in the core layer is removed at 60 to 180°C.

In another embodiment of the present invention, in the step of forming the lower dielectric adhesive layer, the solvent in the lower dielectric adhesive layer is removed at 60 to 180°C.

In another embodiment of the present invention, the compound includes a release layer pressed on the surface of the lower dielectric adhesive layer.

The flexible glued copper foil substrate of the present invention has high adhesive strength, so a copper foil layer with a lower Rz value can be selected, and has a skin effect during signal transmission. Due to the low surface roughness of the low-profile copper foil, the crystal is delicate and the surface The flatness is better, so the signal can realize high-speed transmission, and the upper and lower dielectric adhesive layers have low and stable Dk/Df performance, which can reduce the loss during signal transmission, further improve the signal transmission quality, and do not affect the flexibility The high frequency and high transmission of the circuit board (FPC) can meet the needs of rapid heat dissipation and heat conduction and the development of the lowest production cost.

Furthermore, the Dk value of the dielectric adhesive layer used in the flexible glued copper foil substrate of the present invention is 2.0 to 4.0 (10 GHz), which makes the present invention suitable for rapid lamination at low temperature (below 180°C), strong processability, and Low requirements for production equipment, thereby reducing production costs, its equipment operability and processability are superior to existing liquid crystal polymer substrates and polyimide substrates. In addition, the manufacturing method of the flexible glued copper foil substrate of the present invention is suitable for low temperature lamination, which greatly reduces the risk of line oxidation in the FPC process.

In addition, the material of the core layer of the flexible glued copper foil substrate of the present invention is a liquid crystal polymer containing powder, and the upper and lower dielectric glue layers are mainly composed of polyimide resin. Since the polyimide resin has The low water absorption rate and the filling powder can also effectively reduce the water absorption rate, so the overall water absorption rate of the present invention is 0.19 to 0.4%. Due to its low water absorption rate, the performance after the water absorption is stable and has better electrical performance.

The flexible glue-coated copper foil substrate of the present invention can be added with liquid crystal polymer to fill the powder, which can reduce the thermal expansion coefficient of the liquid crystal polymer core layer and reduce the thermal expansion coefficient of the liquid crystal polymer core layer to 18 to 26 ppm/°C with copper foil The coefficient of thermal expansion (17 to 18ppm/℃) is matched, which further improves the problem of product curling.

In addition to the beneficial effects of good thermal expansion and the like, the invention also has a low rebound force, is suitable for downstream high-density assembly processes, and has the advantages of excellent mechanical properties, good adaptability of laser drilling technology, and the like, and a dielectric adhesive The adhesion strength of the layer is good (greater than 1.01kgf/cm), so this The invented flexible glued copper foil substrate is particularly suitable for use in 5G smart phones, smart watches, bracelets and other wearable devices.

On the other hand, the conventional technology uses a thermoplastic polyimide (Thermoplastic polyimide, TPI) substrate to prepare a thickness of 38 microns or more, the process production efficiency is low, but using the method of the present invention can not only produce a suitable thickness of liquid crystal polymer The substrate and the double-sided copper foil substrate can be easily manufactured with a thickness of 100 microns.

10‧‧‧Core

20, 30‧‧‧ First core layer

20’, 30’‧‧‧second core layer

30”‧‧‧third core layer

10a, 20a, 30a ‧‧‧ first surface

10b, 20b, 30b ‧‧‧ second surface

11, 21, 31 ‧‧‧ copper foil layer

12, 22, 32 ‧‧‧ Upper dielectric adhesive layer

13, 23, 33‧‧‧‧Lower dielectric adhesive layer

101, 201, 201’, 301, 301’, 301”‧‧‧‧filled powder

100, 200, 200’, 300, 300’, 300”‧‧‧‧ liquid crystal polymer

14, 24, 34 ‧‧‧ release layer

The embodiment of the present invention will be described by way of exemplary reference to the drawings: FIG. 1 is a schematic view of the structure of the flexible glued copper foil substrate of the present invention.

FIG. 2 is another schematic structural view of the flexible glued copper foil substrate of the present invention.

FIG. 3 is another schematic structural view of the flexible glued copper foil substrate of the present invention.

The following describes the implementation of the present invention by specific specific examples. Those skilled in the art can easily understand the advantages and effects of the present invention from the contents disclosed in this specification.

It should be noted that the structure, ratio, size, etc. shown in the drawings of this specification are only used to match the content disclosed in the specification, for those who are familiar with this skill to understand and read, not to limit the implementation of the present invention The limited conditions do not have technical significance. Any modification of structure, change of proportional relationship or adjustment of size should still fall within the scope of the invention without affecting the efficacy and the purpose of the invention. The technical content disclosed by the invention can be covered. At the same time, references such as "one", "down" and "upper" in this manual are only It is convenient for description and not intended to limit the scope of the present invention. Changes or adjustments in the relative relationship are regarded as the scope of the present invention without substantial changes in the technical content. In addition, all ranges and values herein are inclusive and combinable. Any value or point that falls within the range described herein, for example, any integer can be used as the minimum or maximum value to derive the lower range.

As shown in FIG. 1, it shows one embodiment of the flexible glued copper foil substrate of the present invention, which includes: a core layer 10 having a first surface 10a and a second surface 10b opposite to each other, and the core layer 10 includes a liquid crystal polymer 100 and a filled powder 101 dispersed in the liquid crystal polymer; an upper dielectric adhesive layer 12 and a lower dielectric adhesive layer 13 are formed on the first surface 10a of the core layer and the second On the surface 10b; the copper foil layer 11 is formed on the upper dielectric adhesive layer 12 so that the upper dielectric adhesive layer 12 is located between the core layer 10 and the copper foil layer 11; and the release layer 14 is formed On the lower dielectric adhesive layer 13, the lower dielectric adhesive layer 13 is located between the core layer 10 and the release layer 14.

In this embodiment, the surface roughness Rz of the copper foil layer in contact with the upper dielectric adhesive layer is 0 to 1.2 μm, and the surface roughness Ra is 0 to 0.4 μm, and the copper foil layer is rolled copper Foil layer or electrolytic copper foil layer.

In an embodiment, the thickness of the core layer is 12 to 75 μm; the thickness of the upper dielectric layer is 1 to 10 μm; the thickness of the lower dielectric layer is 15 to 50 μm; and the copper The thickness of the foil layer is 1 to 35 μm.

In one embodiment, the flexible glued copper foil substrate has two layers of the core layer; in another embodiment, the flexible glued copper foil substrate has three layers of the core layer.

In an embodiment, the upper dielectric layer and the lower dielectric layer have a Dk value of 2.0 to 4.0, and a Df value of 0.001 to 0.010.

In a specific embodiment, the dielectric adhesive layer independently includes at least one of component A and component B and the component A is selected from the group consisting of ceramic powder, sintered silica, Teflon, and The same as Teflon's fluorine-based resin, polyether ether ketone and flame retardant at least one of the group consisting of this component B is selected from epoxy resin, acrylic resin, urethane resin, Silicone rubber-based resin; at least one of the group consisting of parylene-based resin, bismaleimide-based resin and polyimide-based resin.

In a specific embodiment, the component A accounts for 0 to 50% by weight of the total solid content of any one of the upper dielectric adhesive layer and the lower dielectric adhesive layer, and the component B accounts for the upper The total solid content of any one of the dielectric adhesive layer and the lower dielectric adhesive layer is 5 to 80% by weight.

Preferably, the ceramic powder system accounts for 0 to 45% by weight of the total solid content of any of the upper dielectric adhesive layer and the lower dielectric adhesive layer, and the sintered silica system accounts for the upper dielectric adhesive layer and 0 to 45% by weight of the total solid content of any one of the lower dielectric adhesive layers, and the Teflon system accounts for 0 to 45 of the total solid content of any of the upper and lower dielectric adhesive layers % By weight, the fluorine-based resin different from Teflon accounts for 0 to 45% by weight of the total solid content of any of the upper dielectric adhesive layer and the lower dielectric adhesive layer, and the polyetheretherketone accounts for the 0 to 45% by weight of the total solid content of any one of the upper dielectric adhesive layer and the lower dielectric adhesive layer, the flame retardant accounts for the total of any of the upper dielectric adhesive layer and the lower dielectric adhesive layer 0 to 45% by weight of solids.

In a specific embodiment, the ceramic powder system is selected from barium titanate (BaTiO ₃ ), strontium titanate (SrTiO ₃ ), barium strontium titanate (Ba(Sr)TiO ₃ ), and lead titanate (PbTiO ₃ ) , Calcium titanate (CaTiO ₃ ) and magnesium titanate (Mg ₂ TiO ₄ ) at least one group; the fluorine-based resin different from Teflon is selected from polyvinylidene fluoride, vinyl fluoride-vinyl ether Copolymer, tetrafluoroethylene-ethylene copolymer, polychlorotrifluoroethylene-ethylene copolymer, tetrafluoroethylene, hexafluoropropylene-vinylidene fluoride copolymer, tetrafluoroethylene-perfluoroalkyl ethylene copolymer, polytrifluoroethylene At least one of the group consisting of vinyl chloride, polyvinyl chloride, tetrafluoroethylene-hexafluoropropylene copolymer, ethylene-fluoroethylene copolymer, and tetrafluoroethylene-hexafluoropropylene-trifluoroethylene copolymer.

In a specific embodiment, the component A is barium titanate, sintered silica, Teflon and flame retardant, and the component B is polyimide resin.

In another specific embodiment, the component A is barium titanate, strontium titanate, sintered silica, Teflon, and flame retardant, and the component B is polyimide resin.

In an embodiment, the Dk value of the core layer is 2.5 to 4.0, and the Df value is 0.001 to 0.010.

In a specific embodiment, the filled powder system includes at least one of a group consisting of a first filled powder, a second filled powder, and a third filled powder. The first filled powder system is selected from silicon dioxide, At least one of the group consisting of quartz, titanium dioxide, aluminum oxide, zinc oxide, zirconium oxide, magnesium oxide, and aluminum hydroxide; the second filler powder system is selected from calcium carbonate, aluminum carbonate, magnesium carbonate, calcium silicate, silicic acid At least one of the group consisting of magnesium, aluminum silicate, calcium aluminum silicate, calcium magnesium silicate, barium sulfate, talc, clay, kaolin, mica, calcite, wollastonite and dolomite powder; the third filling powder system At least one selected from the group consisting of silicon carbide, boron carbide, boron nitride, polyetheretherketone, and Teflon.

In a specific embodiment, the first filled powder system is silicon dioxide, the second filled powder system is talc powder, and the third filled powder system is boron nitride.

In a specific embodiment, the first filled powder system accounts for 20 to 70% by weight of the total solid content of the core layer, and the second filled powder system accounts for 10 to 30% by weight of the total solid content of the core layer. The three-filled powder system accounts for 0 to 30% by weight of the total solid content of the core layer.

In another embodiment of the present invention, the flexible glued copper foil substrate further includes a release layer 14 formed on the lower dielectric adhesive layer 13 so that the lower dielectric adhesive layer 13 is located on the core layer 10 and the release layer 14, and preferably, the release layer is at least one selected from the group consisting of polypropylene, biaxially oriented polypropylene, and polyethylene terephthalate.

As shown in FIG. 2, it shows another embodiment of the flexible glued copper foil substrate of the present invention, which includes: a first core layer 20 and a second core layer 20 ′. The two sides have opposing first surface 20a and second surface 20b, and the first core layer 20 and the second core layer 20' respectively include liquid crystal polymers 200, 200' and dispersed in the liquid crystal polymers 200, 200' Filled powder 201, 201'; upper dielectric adhesive layer 22 and lower dielectric adhesive layer 23 are formed on the first surface 20a and the second surface 20b respectively; copper foil layer 21 is formed on the On the upper dielectric adhesive layer 22, the upper dielectric adhesive layer 22 is located between the first core layer 20 and the copper foil layer 21; and the release layer 24 is formed on the lower dielectric adhesive layer 23, so that The lower dielectric adhesive layer 23 is located between the second core layer 20 ′ and the release layer 24.

As shown in FIG. 3, it shows another embodiment of the flexible glued copper foil substrate of the present invention, which includes: a first core layer 30, a second core layer 30' and a third core layer 30". The opposite sides of the whole three-layer core layer have opposing first surface 30a and second surface 30b, and the first core layer 30, the second core layer 30' and the third core layer 30" respectively include a liquid crystal polymer 300 , 300', 300" and the filled powder 301, 301', 301" dispersed in the liquid crystal polymer 300, 300', 300"; the upper dielectric adhesive layer 32 and the lower dielectric adhesive layer 33 are formed separately On the first surface 30a and the second surface 30b; the copper foil layer 31 is formed on the upper dielectric adhesive layer 32 so that the upper dielectric adhesive layer 32 is located on the first core layer 30 and the copper foil layer 31; and the release layer 34 is formed on the lower dielectric adhesive layer 33, so that the lower dielectric adhesive layer 33 is located between the third core layer 30" and the release layer 34.

The invention further provides a method for preparing a flexible glue-coated copper foil substrate, which includes the following steps: forming the upper dielectric glue layer on the copper foil layer; forming the core layer on the upper dielectric glue layer to form flexibility Semi-finished products of glued copper foil substrates; tempering the semi-finished products of flexible glued copper foil substrates; and forming a lower dielectric adhesive layer on the core layer of the semi-finished products of flexible glued copper foil substrates tempered so that the core layer is located Between the upper dielectric adhesive layer and the lower dielectric adhesive layer.

In an embodiment, in the step of forming the upper dielectric adhesive layer, the colloidal solution is coated on the copper foil layer by a coating method. Since the colloidal solution contains a solvent, this step is included in The solvent in the upper dielectric adhesive layer is removed at 60 to 180°C.

In another embodiment, in the step of forming the core layer, a polymer solution containing liquid crystal polymer and filled powder is coated on the upper dielectric adhesive layer by a coating method, because the polymer solution It contains solvent, so this step includes removing the solvent in the core layer at 60 to 180℃.

In another embodiment, in the step of forming the lower dielectric adhesive layer, the colloidal solution is coated on the core layer by a coating method. Since the colloidal solution contains a solvent, this step is included in The solvent in the lower dielectric adhesive layer is removed at 60 to 180°C.

In a specific embodiment, the preparation method further includes pressing a release layer on the lower surface of the lower dielectric adhesive layer.

In a specific embodiment, the release layer is at least one selected from the group consisting of polypropylene, biaxially oriented polypropylene, and polyethylene terephthalate.

Examples

Example 1 Preparation of the flexible glued copper foil substrate of the present invention

Mix the components A and B of the upper dielectric adhesive layer according to the weight (g) shown in Table 1, and mix the components A and B of the lower dielectric adhesive layer according to the weight (g) shown in Table 2, And use methyl ethyl ketone as a solvent to form a dielectric adhesive layer. The liquid crystal polymer was mixed with the first filled powder, the second filled powder, and the third filled powder according to the weight (gram) shown in Table 3, and N-methylpyrrolidone (NMP) was used as a solvent to form the core layer.

Forming the upper dielectric adhesive layer on the copper foil layer, and removing the solvent in the upper dielectric adhesive layer at 130°C; forming the core layer on the upper dielectric adhesive layer, and removing the core layer at 160°C Solvent to form a semi-finished product of flexible coated copper foil substrate; placed at 250℃ for 10 hours for tempering treatment The semi-finished flexible glued copper foil substrate forms a lower dielectric glue layer on the core layer of the semi-finished flexible glued copper foil substrate after tempering, and removes the solvent in the lower dielectric glue layer at 130°C, so that The core layer is located between the upper dielectric adhesive layer and the lower dielectric adhesive layer.

Next, the properties of the finished flexible rubber-coated copper foil substrate were tested and recorded in Table 4 below.

Example 2 Preparation of the flexible glued copper foil substrate of the present invention

The flexible glued copper foil substrate of Example 2 is manufactured according to the preparation method of Example 1. The difference is that the ratio is adjusted only according to Tables 1 to 3 to prepare the dielectric adhesive layer and the core layer.

Example 3 Preparation of the flexible glued copper foil substrate of the present invention

The flexible glued copper foil substrate of Example 3 is manufactured according to the preparation method of Example 1. The difference is that the ratio is adjusted according to Tables 1 to 3 only to prepare the dielectric adhesive layer and the core layer.

Example 4 Preparation of the flexible glued copper foil substrate of the present invention

The flexible glued copper foil substrate of Example 4 is manufactured according to the preparation method of Example 1. The difference is that the ratio is adjusted only according to Tables 1 to 3 to prepare the dielectric adhesive layer, the first core layer, and the second core layer.

Example 5 Preparation of the flexible glued copper foil substrate of the present invention

The flexible adhesive-coated copper foil substrate of Example 5 is manufactured according to the preparation method of Example 1. The difference is that the ratio is adjusted according to Tables 1 to 3 only to prepare the dielectric adhesive layer, the first core layer, and the second core layer.

Example 6 Preparation of the flexible glued copper foil substrate of the present invention

The flexible glued copper foil substrate of Example 6 is manufactured according to the preparation method of Example 1, the difference is that the ratio is adjusted according to Tables 1 to 3 only to prepare the dielectric adhesive layer, the first core layer, the second core layer and the first Three core layer.

Example 7 Preparation of the flexible glued copper foil substrate of the present invention

The flexible glued copper foil substrate of Example 7 is manufactured according to the preparation method of Example 1. The difference is that the ratio is adjusted only according to Tables 1 to 3 to prepare the dielectric adhesive layer, the first core layer, the second core layer and the first Three core layer.

Comparative example

Comparative examples 1, 2

The flexible glued copper foil substrates of Comparative Examples 1 and 2 are manufactured according to the preparation method of Example 1. The difference is that the structures of Comparative Examples 1 and 2 do not have an upper dielectric adhesive layer, and the core layer does not contain filler powder.

Comparative Example 3

The flexible glued copper foil substrate of Comparative Example 3 is manufactured according to the preparation method of Example 1, except that the core layer of Comparative Example 3 does not contain filler powder.

Comparative Example 4

The flexible glued copper foil substrate of Comparative Example 4 is manufactured according to the preparation method of Example 1, the difference is that the core layer of Comparative Example 4 uses polyimide instead of liquid crystal polymer, and the core layer does not contain filler powder.

The components, the thickness of each layer, the test method and the performance indexes of Examples 1 to 7 and Comparative Examples 1 to 4 are shown in Table 1 to Table 5.

In Table 5, the Rz value and Ra value of the copper foil layer are the Rz value and Ra value of the adhesion surface of the copper foil layer and the upper dielectric adhesive layer, and the dielectric constant Dk and dielectric loss Df are the dielectric constant Dk and dielectric of the whole substrate Electricity loss Df.

It can be seen from Table 5 that the flexible glued copper foil substrate of the present invention has the advantages of high adhesion strength, better electrical performance, etc., which is beneficial to high-frequency and high-speed transmission, and has low water absorption rate and low thermal expansion coefficient, which is superior to the general Liquid crystal polymer substrates and polyimide substrates are particularly suitable for use in 5G smart phones, smart watches, bracelets and other wearable devices.

The above-mentioned embodiments are only illustrative and not intended to limit the present invention. Anyone who is familiar with this skill can modify and change the above embodiments without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the rights of the present invention is defined by the scope of the patent application attached to the present invention, as long as it does not affect the effects and implementation purposes of the present invention, it should be covered in the disclosed technical content.

10‧‧‧Core

10a‧‧‧First surface

10b‧‧‧Second surface

100‧‧‧Liquid crystal polymer

101‧‧‧filled powder

11‧‧‧Copper foil layer

12‧‧‧Upper dielectric adhesive layer

13‧‧‧Lower dielectric adhesive layer

14‧‧‧ Release layer

Claims (15)

A flexible rubber-coated copper foil substrate includes a core layer having opposing first and second surfaces, and the core layer includes a liquid crystal polymer and a filler powder dispersed in the liquid crystal polymer to make the The core layer has a thermal expansion coefficient of 18 to 26 ppm/°C; the upper dielectric adhesive layer and the lower dielectric adhesive layer are respectively formed on the first surface and the second surface of the core layer; and the copper foil layer is formed on On the upper dielectric adhesive layer, the upper dielectric adhesive layer is located between the core layer and the copper foil layer; wherein, the overall water absorption rate of the flexible glued copper foil substrate is between 0.19% and 0.4%. The flexible rubber-coated copper foil substrate as described in item 1 of the patent scope, wherein the surface roughness Rz of the copper foil layer in contact with the upper dielectric adhesive layer is 0 to 1.2 μm, and the surface roughness Ra is 0 to 0.4 μm, and the copper foil layer is a rolled copper foil layer or an electrolytic copper foil layer. The flexible glue-coated copper foil substrate as described in item 1 of the patent application range, wherein the thickness of the core layer is 12 to 75 μm, the thickness of the upper dielectric layer is 1 to 10 μm, and the lower dielectric layer The thickness is 15 to 50 μm, and the thickness of the copper foil layer is 1 to 35 μm. The flexible glue-coated copper foil substrate as described in item 1 of the patent application range, wherein the flexible glue-coated copper foil substrate has two layers of the core layer or three layers of the core layer. The flexible rubber-coated copper foil substrate as described in item 1 of the patent application range, wherein the Dk values of the upper dielectric adhesive layer and the lower dielectric adhesive layer are both 2.0 to 4.0, and the Df values are both 0.001 to 0.010. The flexible rubber-coated copper foil substrate as described in item 1 of the patent application range, wherein the upper dielectric adhesive layer and the lower dielectric adhesive layer independently include at least one of component A and component B, and the group Sub-A is at least one selected from the group consisting of ceramic powder, sintered silica, Teflon, fluorine-based resins other than Teflon, polyether ether ketone, and flame retardant, and component B is Selected from the group consisting of epoxy resins, acrylic resins, urethane resins, silicone rubber resins, parylene resins, bismaleimide resins and polyimide resins At least one. The flexible rubber-coated copper foil substrate as described in item 6 of the patent application range, wherein the component A accounts for more than 0 to 50 of the total solid content of any of the upper dielectric adhesive layer and the lower dielectric adhesive layer % By weight, and the component B accounts for 5 to 80% by weight of the total solid content of any of the upper dielectric adhesive layer and the lower dielectric adhesive layer. The flexible rubber-coated copper foil substrate as described in item 1 of the patent application range, wherein the Dk value of the core layer is 2.5 to 4.0, and the Df value is 0.001 to 0.010. The flexible rubber-coated copper foil substrate as described in item 1 of the patent application range, wherein the filled powder system includes at least one of the group consisting of a first filled powder, a second filled powder and a third filled powder, wherein , The first filling powder system is selected from at least one group consisting of silicon dioxide, quartz, titanium dioxide, aluminum oxide, zinc oxide, zirconium oxide, magnesium oxide, and aluminum hydroxide, and the second filling powder system is selected from calcium carbonate , Aluminum carbonate, magnesium carbonate, calcium silicate, magnesium silicate, aluminum silicate, calcium aluminum silicate, calcium magnesium silicate, barium sulfate, talc, clay, kaolin, mica, calcite, wollastonite and dolomite powder At least one of the groups, and the third filling powder system is selected from at least one of the group consisting of silicon carbide, boron carbide, boron nitride, polyetheretherketone, and Teflon. The flexible coated copper foil substrate as described in item 9 of the patent application range, wherein the first filler powder system accounts for 20 to 70% by weight of the total solid content of the core layer, and the second filler powder system accounts for the core layer 10 to 30% by weight of the total solids content, the third filled powder system accounts for 0 to 30% by weight of the total solids content of the core layer. The flexible rubber-coated copper foil substrate as described in item 1 of the patent application scope, including a release layer, is formed on the lower dielectric adhesive layer so that the lower dielectric adhesive layer is located between the core layer and the release layer between. A method for preparing a flexible glue-coated copper foil substrate as described in any one of patent application items 1 to 11 includes the following steps: forming the upper dielectric adhesive layer on the copper foil layer; The core layer is formed on the adhesive layer to form a semi-finished product of flexible coated copper foil substrate; the semi-finished product of flexible coated copper foil substrate is tempered, wherein in the step of forming the core layer, the core layer is removed at 60 to 180°C Solvent; and forming a lower dielectric adhesive layer on the core layer of the semi-finished flexible glued copper foil substrate after tempering so that the core layer is located between the upper dielectric adhesive layer and the lower dielectric adhesive layer. The preparation method as described in Item 12 of the scope of the patent application includes the step of removing the solvent in the upper dielectric adhesive layer at 60 to 180°C in the step of forming the upper dielectric adhesive layer. The preparation method as described in item 12 of the patent application scope further includes removing the solvent in the lower dielectric adhesive layer at a temperature of 60 to 180°C in the step of forming the lower dielectric adhesive layer. According to the preparation method described in item 12 of the patent application scope, the method further includes pressing a release layer on the surface of the lower dielectric adhesive layer.

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