TWI664086B - Double-sided copper foil substrate with fluorine polymer and high frequency and high transmission characteristics and the preparation method thereof and composite - Google Patents

Abstract

Double-sided copper foil substrate with fluorine-based polymer and high-frequency and high-transmission characteristics and preparation method, the double-sided copper foil substrate includes a first copper foil layer, a first insulating polymer layer, and a first extremely low dielectric An adhesive layer, a core layer, a second very low dielectric adhesive layer, a second insulating polymer layer, and a second copper foil layer, wherein the first and second insulating polymer layers are all fluorine-based polymer layers; the first and The dielectric constant value of the second extremely low dielectric adhesive layer is 2.0 to 3.50, and the dielectric loss value is 0.002 to 0.010. The surface roughness values of the first and second copper foil layers are 0.1 to 1.6 microns.

Description

Double-sided copper foil substrate with fluorine-based polymer and high frequency and high transmission characteristics, preparation method and composite material

The invention relates to a double-sided copper foil substrate for a flexible printed circuit board (FPC) and a preparation method thereof, and more particularly, to a double-sided copper foil substrate having a fluorine-based polymer and high frequency and high transmission characteristics and a preparation method thereof. And composite materials.

With the rapid development of information technology, in order to meet the high-frequency and high-speed signal transmission, rapid heat dissipation and heat dissipation, and minimization of production costs, the design and application of various forms of mixed-pressure multi-layer boards are in the ascendant. Printed circuit boards are an indispensable material in electronic products, and as the demand for consumer electronics products grows, the demand for printed circuit boards is also increasing. Because flexible printed circuit boards (FPC, Flexible Printed Circuit) have characteristics such as flexibility and three-dimensional space wiring, under the development trend of technology-oriented electronic products that emphasize lightness, shortness, flexibility, and high frequency, they are currently widely used. Application computer and its peripheral equipment, communication products and consumer electronics products, etc.

In the high-frequency field, wireless infrastructure needs to provide a sufficiently low insertion loss to effectively improve energy efficiency. With the advent of 5G communications, millimeter-wave, and aerospace military industries accelerating high-frequency and high-speed FPC / PCB (printed circuit board) demand, the emergence of emerging industries such as big data, the Internet of Things, and the popularity of mobile interconnect terminals, fast processing, Transmission of information has become the focus of the communications industry. In the field of communications, 5G networks will have higher speed bandwidth and denser micro base station construction than 4G in the future, and the network speed will be faster. The Internet of Things and cloud computing, as well as the needs of broadband communications in the new generation, the development of high-speed servers and mobile phones with higher transmission rates has become a market trend. Generally speaking, FPC / PCB is the main bottleneck in the entire transmission process. If it lacks good design and related electrical materials, it will seriously delay the transmission rate or cause signal loss. This places high demands on circuit board materials. In addition, the current high-frequency boards used in the industry are mainly LCP (liquid crystal polymer) boards and PTFE (polytetrafluoroethylene) fiber boards. However, they are also limited by process technology. They require high manufacturing equipment and require higher temperature environments. (Above 280 ℃), it can be operated at the same time, which also causes the uneven thickness of the film. The uneven thickness will cause the resistance of the circuit board to be difficult to control, and the high temperature pressing process will cause the LCP or PTFE extrusion to affect the plating. The continuity of copper forms a disconnection, which results in poor reliability and decreased reliability; in addition, it is difficult to use fast press equipment, which causes processing difficulties; in addition, in SMT (surface mount) high temperature processes or other FPC processes, such as In the process of bending, strong acid and alkali medicine solution, the strength is insufficient, resulting in a decrease in yield. While other resin film layers do not have the above problems, they also face problems such as poor electrical properties or poor mechanical strength.

Therefore, the industry still needs to develop a novel double-sided copper foil substrate to solve the problem. Many of the above issues.

The signal integrity is very important at high frequency and high speed transmission. The main factors affecting the copper foil layer and the insulating polymer layer base material. The double-sided copper foil substrate as the raw material of the FPC / PCB board is mainly composed of multiple insulating polymer layers and copper foil.层 结构。 Layer composition. The performance of the double-sided copper foil substrate depends to a large extent on the choice of the lower dielectric constant / dielectric loss resin layer and the choice of copper foil surface roughness and lattice arrangement.

In order to solve the above technical problems, the present invention provides a double-sided copper foil substrate having a fluorine-based polymer and high frequency and high transmission characteristics. The double-sided copper foil substrate of the present invention not only has good electrical properties but also has low-roughness copper. Foil layer, simple structure composition, cost advantage, short process steps, low thermal expansion coefficient, stable dielectric constant / dielectric loss performance under high temperature and humidity environment, ultra-low water absorption, good UV laser drilling ability, Low rebound force is suitable for high-density assembly and excellent mechanical properties.

The invention provides a double-sided copper foil substrate with a fluorine polymer and high frequency and high transmission characteristics. The copper foil substrate includes a core layer having a thickness of 5 to 50 micrometers and containing polyimide. A second surface; a first extremely low dielectric adhesive layer having a thickness of 2 to 50 microns, a first insulating polymer layer having a thickness of 5 to 100 microns, and a thickness of A first copper foil layer of 1 to 35 micrometers; and a second very low dielectric adhesive layer having a thickness of 2 to 50 micrometers and a second layer of 5 to 100 micrometers sequentially formed on the second surface of the core layer An insulating polymer layer and a second copper foil layer having a thickness of 1 to 35 microns; The total thickness of the double-sided copper foil substrate is 21 to 420 microns; the dielectric constants (Dk values) of the first extremely low dielectric adhesive layer and the second extremely low dielectric adhesive layer are 2.0 to 3.50, The electrical loss (Df value) is 0.002 to 0.010; the first insulating polymer layer and the second insulating polymer layer include a fluorine-based polymer, and their dielectric constants (Dk values) are 2.0 to 3.50, and the dielectric loss (Df value) are 0.0002 to 0.001; and the surface roughness of the first copper foil layer and the second copper foil layer in contact with the first insulating polymer layer and the second insulating polymer layer are 0.1 respectively. Up to 1.6 microns.

Preferably, the thickness of the first copper foil layer and the second copper foil layer are both 1 to 35 microns; the thickness of the first insulating polymer layer and the second insulating polymer layer are both 5 to 100 microns; The thickness of the first extremely low dielectric glue layer and the second extremely low dielectric glue layer are both 2 to 50 microns; the thickness of the core layer is 5 to 50 microns.

In a specific embodiment, the fluorine-based polymer is selected from the group consisting of polytetrafluoroethylene, polyvinylidene fluoride, copolymers of vinyl fluoride and vinyl ether, copolymers of tetrafluoroethylene and ethylene, polytrifluorochloroethylene and Ethylene copolymer, hexafluoropropylene and vinylidene fluoride copolymer, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, polytrifluorochloroethylene, polyvinyl chloride, tetrafluoroethylene-hexafluoropropylene copolymer, ethylene -At least one of the group consisting of a fluoroethylene copolymer and a tetrafluoroethylene-hexafluoropropylene-trifluoroethylene copolymer.

In a specific embodiment, the water absorption rate of the entire double-sided copper foil substrate is 0.01 to 0.10%.

In a specific embodiment, the first copper foil layer, the first insulating polymer layer, the first extremely low dielectric adhesive layer, the core layer, and the second extremely low dielectric adhesive. The bonding strength between the layer, the second insulating polymer layer, and the second copper foil layer were all greater than 0.8 kgf / cm.

In a specific embodiment, the resin materials of the first extremely low-dielectric adhesive layer and the second extremely low-dielectric adhesive layer are independently selected from the group consisting of fluorine-based resin, epoxy resin, acrylic resin, and urethane. At least one of the group consisting of an ester-based resin, a silicone rubber-based resin, a parylene resin, a bismaleimide-based resin, and a polyimide-based resin.

In a specific embodiment, the first extremely low-dielectric adhesive layer and the second extremely low-dielectric adhesive layer are a thermosetting polyimide layer comprising polyimide.

In a specific embodiment, the polyimide content in the first extremely low dielectric adhesive layer is 40 to 95% by weight of the total solid content of the first extremely low dielectric adhesive layer, and the second extremely low The polyimide content in the dielectric adhesive layer is 40 to 95% by weight of the total solids content of the second extremely low dielectric adhesive layer.

In a specific embodiment, when the fluorine-based polymer in the first insulating polymer layer accounts for 60% to less than 80% of its total solid content, its water absorption is 0.5 to 0.6%, and the dielectric constant is 3.5. The dielectric loss is 0.009; and when the fluorine-based polymer in the second insulating polymer layer accounts for 60% to less than 80% of its total solid content, the water absorption is 0.5 to 0.6%, and the dielectric constant is 3.5. The dielectric loss is 0.009.

In a specific embodiment, when the fluorine-based polymer in the first insulating polymer layer accounts for 80% to less than 90% of its total solid content, the water absorption rate is 0.1 to 0.2%, and the dielectric constant is 3.2. When the dielectric loss is 0.005, and the fluorine-based polymer in the second insulating polymer layer accounts for 80% to 90% of its total solid content, the water absorption is 0.1 to 0.2%, and the dielectric constant is 3.2, The dielectric loss is 0.005.

In a specific embodiment, when the fluorine-based polymer in the first insulating polymer layer accounts for 90% to less than 100% of its total solid content, its water absorption is 0.01 to 0.02%, and the dielectric constant is 3.0. When the dielectric loss is 0.003, and the fluorine-based polymer in the second insulating polymer layer accounts for 90% to less than 100% of its total solid content, the water absorption is 0.01 to 0.02%, and the dielectric constant is 3.0. The dielectric loss is 0.003.

The present invention further provides a composite material for a flexible printed circuit board (FPC), comprising: the double-sided copper foil substrate of the present invention; and a backed flexible copper foil substrate (FRCC). The backed flexible copper foil substrate includes a first Three copper foil layers, a polyimide layer and a third extremely low-dielectric adhesive layer sequentially formed on the surface of the third copper foil layer, and the adhesive-backed flexible copper foil substrate uses the third extremely low-dielectric substrate. The electro-adhesive is laminated on the first copper foil layer of the double-sided copper foil substrate.

In one embodiment of the composite material, a surface roughness (Rz value) of a surface of the third copper foil layer in contact with the polyimide layer is 0.1 to 1.0 μm.

The invention further provides a method for preparing a double-sided copper foil substrate having a fluorine-based polymer and having high frequency and high transmission characteristics. The method includes: coating a surface of the first copper foil layer with a fluorine-based polymer, and The solvent in the fluorine-based polymer is removed at 100 ° C to form a first insulating polymer layer; the surface of the second copper foil layer is coated with a fluorine-based polymer, and the fluorine-based polymer is removed at 60 to 100 ° C. Solvent to form a second insulating polymer layer; coating an extremely low dielectric adhesive on two opposite surfaces of the polyimide layer, and drying the extremely low dielectric adhesive at 60 to 100 ° C to form a first Very low dielectric glue layer and second very low dielectric glue Layer; the first insulating polymer is laminated on the surface of the first ultra-low dielectric adhesive layer under the conditions of a pressing pressure of 1 to 5 kgf / cm² and a pressing temperature of 100 to 160 ° C. , Laminating the second insulating polymer on the surface of the second extremely low-dielectric adhesive layer; and reacting for 0.5 to 1.5 hours at a temperature of 190 to 210 ° C., winding and heating to form a composite type Fluoropolymer high frequency high transmission double-sided copper foil substrate.

The invention further provides a method for preparing a double-sided copper foil substrate having a fluorine-based polymer and having high-frequency and high-transmission characteristics. The method includes: applying a double-layer coating technique to a fluorine-based polymer on a surface of a first copper foil layer. And extremely low dielectric adhesive are applied on the first copper foil layer at the same time, and the solvent is removed at 60 to 100 ° C. to sequentially form a first insulating polymer layer and a first extremely low dielectric on the first copper foil layer. Electro-adhesive layer; coating the second copper foil layer with a fluoropolymer and an extremely low dielectric adhesive on the surface of the second copper foil layer by a double-layer coating technique, and removing the solvent at 60 to 100 ° C, A second insulating polymer layer and a second extremely low dielectric adhesive layer are sequentially formed on the second copper foil layer; the lamination pressure is 1 to 5 kgf / cm², and the lamination temperature is 100 to 160 ° C. Under the conditions, the first extremely low dielectric adhesive layer and the second extremely low dielectric adhesive layer are laminated on the opposite two surfaces of the polyimide layer; and the reaction is performed at a temperature of 190 to 210 ° C for 0.5 to After 1.5 hours, it was rolled up and heated to form a composite fluorine polymer high frequency and high transmission double-sided copper foil substrate.

According to the present invention, the double-sided copper foil substrate system has at least the following advantages:

1. The insulating polymer layer of the double-sided copper foil substrate of the present invention is a fluorine-based polymer layer. The fluorine-based polymer in the fluorine-based polymer layer has ultra-low hygroscopicity, so that the fluorine-containing polymer layer Double-sided copper foil substrate also has ultra-low water absorption Rate, as low as 0.01 to 0.10%, stable performance after absorbing water, and better electrical performance, which can greatly reduce the risk of bursting of multi-layer boards and flexible and rigid boards, and reduce signal transmission insertion loss; The dielectric constant and dielectric loss are relatively low, and its dielectric loss is as low as 0.0002 to 0.001, which makes the double-sided copper foil substrate of the present invention not only have excellent heat resistance, peel strength and flame retardancy, but also exhibits its dielectric properties. The constant is lower than the dielectric constant of the flexible copper-clad board in the prior art, and is suitable for manufacturing flexible printed circuit boards in high-frequency and high-speed application fields.

2. The double-sided copper foil substrate of the present invention has a reasonable structure, can reduce the manufacturing process of FPC factory, has good electrical properties, and has a low-roughness copper foil, a low thermal expansion coefficient, and a stable dielectric constant under high temperature and humidity environments. Dielectric loss performance, ultra-low water absorption, and excellent mechanical properties, good flexibility, high solder resistance, good bonding strength, good operability, and can be laminated at low temperatures, fast pressing equipment, and pressure After the combination, the FPC has excellent flatness, so it is suitable for UV laser processing of small apertures smaller than 100 microns, uniform film thickness and good impedance control during lamination. It is suitable for wearable devices such as 5G smartphones and Apple watches. .

3. The composite material for a flexible printed circuit board (FPC) of the present invention includes first, second, and third copper foil layers, that is, has three copper foil layers, and is pressed by FRCC and a double-sided copper foil substrate. The third copper foil layer and the second copper foil layer are copper foil layers on the outside, which require high temperature (about 260 ° C) soldering and mounting of components, so the peeling strength requirements are higher (greater than 0.7 kgf). / Cm2), and the first copper foil layer is an inner copper foil layer located in the middle, also known as a signal line copper foil layer, which is mainly used for conducting lines and does not need to go through SMT Or other high-temperature process-mounted components, the peel strength requirement only needs to be greater than 0.5 kgf / cm².

The traditional idea is that the bonding strength between the copper foil layer and other layers in FPC is better within a certain range (at least greater than 0.7 kgf / cm), and the more difficult it is to peel off, however, the greater the bonding strength, the more generally The surface roughness (Rz) value of the copper foil layer is relatively large. Relatively speaking, the signal transmission process of the copper foil layer has a skin effect. In order to achieve high frequency and high transmission, the surface roughness (Rz) of the copper foil layer is required. The smaller the value is, the better. To sum up, there is a contradiction between the larger bonding strength and high frequency and high transmission.

In contrast, the first copper foil layer of the composite material for a flexible printed circuit board (FPC) of the present invention does not need to be equipped with components through SMT or other high-temperature processes, making it extremely low for the first copper foil layer and the second copper foil layer. The dielectric adhesive layer has a lower peel strength requirement, and only needs to be greater than 0.5 kgf / cm2, so the first copper foil layer can choose a lower surface roughness (Rz) value, better electrical properties, and more insertion loss. Low copper foil without affecting the high frequency and high transmission of FPC.

4. The surface roughness (Rz) values of the third copper foil layer, the first copper foil layer and the second copper foil layer used in the composite material for flexible printed circuit board (FPC) of the present invention are relatively low, and the signal transmission It has a skin effect during the process, and because of the low surface roughness of the copper foil, it makes the crystals fine and the surface flatness is better, so the signal can achieve high-speed transmission. At the same time, the extremely low dielectric adhesive layer has a low and stable The dielectric constant / dielectric loss performance can reduce the loss in the signal transmission process, and further improve the signal transmission quality. It is fully capable of high-frequency high-speed FPC, fast heat dissipation and heat dissipation, and minimum production cost.

5. The first and second extremely low-dielectric adhesive layers in the present invention are adhesive layers having a dielectric constant value of 2.0 to 3.5 and a dielectric loss value of 0.002 to 0.010. The stable dielectric constant / dielectric loss value makes the FRCC and the double-sided copper foil substrate suitable for rapid lamination at low temperature (less than 180 ° C) to obtain the FPC of the present invention. The FPC process of the present invention has strong processability, and The requirements for production equipment are low, which further reduces the production cost. Its equipment operability and processability are better than existing LCP substrates and PTFE fiberboards. Better, because it is suitable for low temperature lamination, it can greatly reduce the line oxidation during the preparation of FPC. risks of.

6. The first and second extremely low-dielectric adhesive layers of the present invention may be polyimide-containing thermosetting polyimide layers, and the content of polyimide is the weight of the total solid content of the extremely low-dielectric adhesive layer. 40 to 95%, using a structure of a thermosetting polyimide layer and an insulating polymer layer. Compared with traditional epoxy resin products, the double-sided copper foil substrate of the present invention has a small aperture (less than 100 micron) UV laser processing, which is not easy to cause PTH (Plating Through Hole) or hole shrinkage, uniform film thickness and good impedance control during lamination, not only suitable for mechanical drilling with larger apertures, Strong process adaptability.

7. Compared with the ordinary LCP board, the double-sided copper foil substrate in the present invention has a lower rebound force, which is only about half of the rebound force of the LCP board, which is suitable for high density downstream. Assembly process.

8. The double-sided copper foil substrate of the present invention has the advantages of good thermal expansion, good flexibility, high solder resistance, and excellent mechanical properties, and the bonding strength of the extremely low dielectric adhesive layer is good, and the bonding strength is greater than 0.8 kgf / cm.

Nine. When the current Bond Ply products are used in downstream industries, it is necessary to peel off the release layer and press the copper foil layer. However, the double-sided copper foil substrate with this structure has a simple structure and can save downstream Processing procedures, the cost is relatively low.

100‧‧‧ double-sided copper foil substrate

101‧‧‧The first copper foil layer

102‧‧‧First insulating polymer layer

103‧‧‧The first extremely low dielectric adhesive layer

104‧‧‧ core layer

105‧‧‧Second Very Low Dielectric Adhesive Layer

106‧‧‧ second insulating polymer layer

107‧‧‧Second copper foil layer

200‧‧‧ Adhesive flexible copper foil substrate

201‧‧‧The third copper foil layer

202‧‧‧Third Very Low Dielectric Adhesive Layer

203‧‧‧Polyimide layer

The embodiments of the present invention will be described by way of example with reference to the accompanying drawings: FIG. 1 is a schematic structural diagram of a double-sided copper foil substrate having a fluorine polymer and high frequency and high transmission characteristics according to the present invention; and FIG. 2 is a schematic view of the present invention. Schematic diagram of a method for manufacturing a double-sided copper foil substrate pressure-bonded flexible copper foil substrate (FRCC); FIG. 3 is a schematic diagram of a method for preparing a double-sided copper foil substrate of the present invention; and FIG. 4 is a double-sided copper foil substrate of the present invention Schematic of another preparation method.

The following is a description of specific embodiments of the present invention. Those skilled in the art can easily understand the advantages and effects of the present invention from the content disclosed in this specification.

It should be noted that the structures, proportions, sizes, etc. shown in the drawings in this specification are only used to match the content disclosed in the specification for the understanding and reading of those skilled in the art, and are not intended to limit the implementation of the present invention. The limited conditions are not technically significant. Any modification of the structure, change of the proportional relationship, or adjustment of the size should still fall within the scope of this invention without affecting the effects and goals that can be achieved by the present invention. Disclosed Technology The content must be within the scope. At the same time, the references such as “一”, “下” and “上” in this specification are for clarity only, and are not intended to limit the scope of the present invention. Substantially changing the technical content should also be regarded as the scope in which the present invention can be implemented. 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, etc.

As shown in FIG. 1, it shows a specific embodiment of the double-sided copper foil substrate 100 having a fluorine-based polymer and high frequency and high transmission characteristics according to the present invention, and includes a core layer having a thickness of 5 to 50 μm. The core layer 104 has a first surface and a second surface opposite to each other; the first extremely low-dielectric adhesive layer 103 having a thickness of 2 to 50 microns is sequentially formed on the first surface of the core layer 104 and the thickness is 5 A first insulating polymer layer 102 to 100 micrometers, and a first copper foil layer 101 having a thickness of 1 to 35 micrometers; and a second layer having a thickness of 2 to 50 micrometers sequentially formed on the second surface of the core layer 104 Very low dielectric adhesive layer 105, second insulating polymer layer 106 having a thickness of 5 to 100 micrometers, and second copper foil layer 107 having a thickness of 1 to 35 micrometers; wherein the total thickness of the double-sided copper foil substrate 100 It is 21 to 420 microns; the core layer 104 includes polyimide; and the dielectric constants (Dk values) of the first extremely low-dielectric adhesive layer 103 and the second extremely low-dielectric adhesive layer 105 are 2.0 to 3.50, Dielectric loss (Df value) is 0.002 to 0.010; the first insulating polymer layer 102 and the second insulating polymer layer 106 include a fluorine-based polymer, and their dielectric constants ( Dk value) are all 2.0 to 3.50, dielectric loss (Df value) are all 0.0002 to 0.001; and the first and second insulating polymer layers 102 and 106 are in contact with the first insulating polymer layer 106 respectively. The surface roughness of the surfaces of the copper foil layer 101 and the second copper foil layer 107 is 0.1 to 1.6 μm.

In this embodiment, preferably, the first copper foil layer 101 and the second copper foil layer 107 are both a rolled copper foil layer (RA / HA / HAV2) or an electrolytic copper foil layer (ED).

The fluorine-based polymer is selected from polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), a copolymer of vinyl fluoride and vinyl ether (FEVE), a copolymer of tetrafluoroethylene and ethylene (ETFE), and polytrifluoroethylene. Fluorochloroethylene and ethylene copolymer (ECTFE), hexafluoropropylene and vinylidene fluoride copolymer (THV), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), polytrifluorochloroethylene (PCTFF), Polyvinyl chloride (PVF), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), ethylene-fluoroethylene copolymer (ETF), and tetrafluoroethylene-hexafluoropropylene-trifluoroethylene copolymer (TFB) At least one of a group.

The first copper foil layer 101, the second copper foil layer 107, the first insulating polymer layer 102, the two insulating polymer layers 106, the first extremely low dielectric adhesive layer 103, and the second extremely low dielectric The water absorption of the double-sided copper foil substrate 100 composed of the electro-adhesive layer 105 and the core layer 104 is 0.01 to 0.10%.

The first copper foil layer 101, the first insulating polymer layer 102, the first extremely low dielectric adhesive layer 103, the core layer 104, the second extremely low dielectric adhesive layer 105, and the second insulating polymer The bonding strength between the layer 106 and the second copper foil layer 107 is more than 0.8 kgf / cm.

The resin materials of the first extremely low-dielectric adhesive layer 103 and the second extremely low-dielectric adhesive layer 105 are independently selected from fluorine-based resins, epoxy resins, acrylic resins, urethane resins, and silicone rubbers. Resin, parylene resin, At least one of the group consisting of bismaleimide resin and polyimide resin.

In a specific embodiment, the first extremely low-dielectric adhesive layer 103 and the second extremely low-dielectric adhesive layer 105 are thermosetting polyimide layers including polyimide. The polyimide content in the first extremely low-dielectric adhesive layer 103 is 40 to 95% by weight of the total solid content of the first extremely low-dielectric adhesive layer 103. The polyimide content is 40 to 95% by weight of the total solid content of the second very low dielectric adhesive layer 105.

In a specific embodiment, when the fluorine-based polymer in the first insulating polymer layer 102 accounts for 60% to less than 80% of its total solid content, the water absorption rate is 0.5 to 0.6%, and the dielectric constant is When the fluorinated polymer in the second insulating polymer layer 106 accounts for 60% to less than 80% by weight of the total solid content, the water absorption is 0.5 to 0.6%, the dielectric The constant is 3.5 and the dielectric loss is 0.009. In a specific embodiment, when the fluorine-based polymer in the first insulating polymer layer 102 accounts for 80% to less than 90% of its total solid content by weight, it absorbs water. When the rate is 0.1 to 0.2%, the dielectric constant is 3.2, and the dielectric loss is 0.005, and the fluorine-based polymer in the second insulating polymer layer 106 accounts for 80% to less than 90% of the total solid content by weight, The water absorption rate is 0.1 to 0.2%, the dielectric constant is 3.2, and the dielectric loss is 0.005. In a specific embodiment, the fluorine-based polymer in the first insulating polymer layer 102 accounts for 90% of its total solid content by weight. % To less than 100%, the water absorption rate is 0.01 to 0.02%, the dielectric constant is 3.0, the dielectric loss is 0.003, and the fluorine-based polymerization in the second insulating polymer layer 106 is polymerized. Of its total solid content When the weight is 90% to less than 100%, the water absorption is 0.01 to 0.02%, the dielectric constant is 3.0, and the dielectric loss is 0.003.

As shown in FIG. 2, it is a schematic diagram showing a method for manufacturing a double-sided copper foil substrate press-bonded flexible copper foil substrate (FRCC) according to the present invention. In order to obtain a composite material for a flexible printed circuit board (FPC), a third extremely low dielectric adhesive layer 202 of a backed flexible copper foil substrate (FRCC) 200 is laminated to the double-sided copper foil substrate 100 of the present invention. In this embodiment, the preparation method is pre-pressing, pressing, and curing the adhesive-backed flexible copper foil substrate (FRCC) 200 and the double-sided copper foil substrate 100, wherein the pre-pressing time is 10 to 30 seconds and the molding time is 120 to 180 seconds, forming pressure is 90 to 110 kgf / cm², pressing temperature is 175 to 195 ° C, aging temperature is 165 to 175 ° C, and aging time is 50 to 60 minutes.

Preferably, the forming pressure is 100 kgf / cm 2, the aging temperature is 170 ° C., and the aging time is 60 minutes.

The obtained composite material for a flexible printed circuit board (FPC) includes: the double-sided copper foil substrate 100 and the adhesive-backed flexible copper foil substrate (FRCC) 200 of the present invention, which includes a third copper foil layer 201, in order, A polyimide layer 203 and a third ultra-low-dielectric-adhesive layer 202 formed on the surface of the third copper foil layer 201, and the adhesive-backed flexible copper foil substrate 200 is based on the third ultra-low-dielectric-adhesive layer. 202 is laminated on the first copper foil layer 101 of the double-sided copper foil substrate 100.

In this aspect, the surface roughness (Rz value) of the surface of the third copper foil layer 201 that is in contact with the polyimide layer 203 is 0.1 to 1.0 micrometer.

As shown in FIG. 3, the present invention further provides a fluorine-containing polymer and A method for preparing a double-sided copper foil substrate with high frequency and high transmission characteristics includes: coating a surface of a fluorine-based polymer on the surface of the first copper foil layer 101, and removing the fluorine-based polymer from 60 to 100 ° C. A solvent to form a first insulating polymer layer 102; a fluorine-based polymer is coated on the surface of the second copper foil layer 107; and the solvent in the fluorine-based polymer is removed at 60 to 100 ° C to form a second insulation Polymer layer 106; coating an extremely low dielectric adhesive on two opposite surfaces of the polyimide layer (ie, the core layer 104), and drying the extremely low dielectric adhesive at 60 to 100 ° C to form a first electrode The low-dielectric adhesive layer 103 and the second extremely low-dielectric adhesive layer 105; the first insulating polymer is under the conditions of a pressing pressure of 1 to 5 kgf / cm² and a pressing temperature of 100 to 160 ° C. The layer 102 is laminated on the surface of the first extremely low dielectric adhesive layer 103, the second insulating polymer layer 106 is laminated on the surface of the second extremely low dielectric adhesive layer 105; and the temperature is 190 to 210 The reaction is performed at a temperature of 0.5 ° C. for 1.5 to 1.5 hours, and the coil is heated by heating to form a composite fluorine polymer double-sided copper foil substrate with high frequency and high transmission.

As shown in FIG. 4, the present invention further provides another method for preparing a double-sided copper foil substrate having a fluorine-based polymer and high-frequency and high-transmission characteristics. The method includes: The layer coating head technology simultaneously coats the first copper foil layer 101 with a fluoropolymer and an extremely low dielectric adhesive, and removes the solvent at 60 to 100 ° C. to sequentially form a first layer on the first copper foil layer 101. An insulating polymer layer 102 and a first ultra-low-dielectric-adhesive layer 103; and a second-layer coating technique is applied on the surface of the second copper foil layer 107 to coat the second fluoropolymer and the ultra-low-dielectric-adhesive simultaneously. On the copper foil layer, the solvent is removed at 60 to 100 ° C, so that a second insulating polymer layer 106 and a second extremely low dielectric adhesive layer 105 are sequentially formed on the second copper foil layer 107; 1 to 5 kgf / cm2, The first extremely low-dielectric adhesive layer 103 and the second extremely low-dielectric adhesive layer are laminated on two opposite surfaces of the polyimide layer (that is, the core layer 104) under a compression temperature of 100 to 160 ° C. 105; and react at a temperature of 190 to 210 ° C. for 0.5 to 1.5 hours, and rewind and heat to form a composite fluorine polymer high-frequency high-transmission double-sided copper foil substrate.

Examples

The thickness, composition and source of each layer in Examples 1 to 6 are shown in Tables 1-1 to 1-4.

The source of each component is shown in Table 1-4 below.

Tables 2 and 3 show the specific stacking structure and basic properties of the double-sided copper foil substrates of Examples 1 to 6 and Comparative Examples 1 and 2. Each property in the table is based on the "Testing Criteria for Assembly of Flexible Boards TPCA-F" -002》 as the test conditions, the results are as follows.

In Table 2, the components of the first insulating polymer layer, the second insulating layer, the first extremely low-dielectric adhesive layer, and the second extremely low-dielectric adhesive layer of each embodiment are as shown in Table 1-1 to Table 1. -3; the LCP substrate (50um) of Comparative Example 1 is an R-F705T 23RX-M substrate purchased from Panasonic; and the LCP substrate (100um) of Comparative Example 2 is an R-F705T purchased from Panasonic. 43RX-M substrate.

The basic performance comparison between the specific embodiment of the present invention and the prior art LCP board is shown in Table 3 below.

As can be seen from Table 3, the double-sided copper foil substrate of the present invention has excellent performance, so the composite fluoropolymer high-frequency and high-frequency double-sided copper foil substrate has excellent high-speed transmission properties, low thermal expansion coefficient, and high temperature. Stable dielectric constant / dielectric loss performance under humidity environment, ultra-low water absorption, good UV laser drilling ability, low rebound force suitable for high-density assembly, and excellent mechanical properties.

The invention is superior to the LCP film and the ordinary PI-type bond sheet, and is suitable for wearable devices such as 5G smart phones, Apple watches and the like.

In addition, in the specific embodiment shown in Figure 2, the composite material for a flexible printed circuit board (FPC) includes first, second, and third copper foil layers, the structure is reasonable, and FRCC and double-sided copper The foil substrate is laminated, and the third copper foil layer and the second copper foil layer are the outer copper foil layers, which require high temperature (260 ° (Left and right) Soldering and mounting components, so the peeling strength requirements of the two are higher (greater than 0.7 kgf / cm2), and the first copper foil layer is the inner copper foil layer in the middle, also known as the signal wire copper foil layer It is mainly used for conducting lines, and it does not need to carry components through SMT or other high-temperature processes. Therefore, the peel strength of the first copper foil layer and the second extremely low dielectric adhesive layer is relatively low. It only needs to be greater than 0.5 kgf / cm2. That is, the traditional concept has always believed that the bonding strength of the copper foil layer and other layers in the FPC is greater in a certain range, the better (at least greater than 0.7 kgf / cm), the less it is easy to delaminate, and large bonding strength is generally required The surface roughness of the copper foil layer is relatively large. In addition, the signal transmission process of the copper foil layer has a skin effect. To achieve high frequency and high transmission, the smaller the surface roughness of the copper foil layer, the better. There is a contradiction between the bonding strength of the high-frequency and high-frequency high-transmission, and the composite material used in the flexible printed circuit board (FPC) of the present invention does not need to pass SMT or other high-temperature processes to mount components for the first copper foil layer. Foil layer and second extremely low dielectric The peel strength of the electro-adhesive layer is relatively low. It only needs to be greater than 0.5 kgf / cm². Therefore, the first copper foil layer can select a copper foil layer with a lower surface roughness value, better electrical properties, and lower insertion loss. , And does not affect the high frequency and high transmission of FPC.

The above-mentioned embodiments are merely illustrative and not intended to limit the present invention. Anyone skilled in the art 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 effect and implementation purpose of the present invention, it should be covered in this disclosed technical content.

Claims (14)

A double-sided copper foil substrate with a fluorine-based polymer and high frequency and high transmission characteristics, comprising: a core layer having a thickness of 5 to 50 micrometers and containing polyimide, and having opposite first and second surfaces ; A first extremely low dielectric adhesive layer having a thickness of 2 to 50 microns, a first insulating polymer layer having a thickness of 5 to 100 microns, and a thickness of 1 to 35, which are sequentially formed on the first surface of the core layer; A first copper foil layer of micrometers; and a second extremely low-dielectric adhesive layer having a thickness of 2 to 50 micrometers and a second insulating polymer having a thickness of 5 to 100 micrometers sequentially formed on the second surface of the core layer Layer, and a second copper foil layer having a thickness of 1 to 35 micrometers; wherein the total thickness of the double-sided copper foil substrate is 21 to 420 micrometers; the first extremely low dielectric adhesive layer and the second extremely low dielectric adhesive The dielectric constant (Dk value) of the layer is 2.0 to 3.50, and the dielectric loss (Df value) is 0.002 to 0.010. The first insulating polymer layer and the second insulating polymer layer each contain a fluorine-based polymer. And the dielectric constant (Dk value) thereof is 2.0 to 3.50, and the dielectric loss (Df value) thereof is 0.0002 to 0.001; and the first insulating polymer layer and The surface roughness of the surfaces of the first copper foil layer and the second copper foil layer in contact with the second insulating polymer layer are both 0.1 to 1.6 microns. The double-sided copper foil substrate with a fluorine-based polymer and high-frequency and high-transmission characteristics as described in item 1 of the scope of the patent application, wherein the fluorine-based polymer is selected from polytetrafluoroethylene, polyvinylidene fluoride, and fluorine Copolymer of ethylene and vinyl ether, copolymer of tetrafluoroethylene and ethylene, copolymer of polytrifluorochloroethylene and ethylene, copolymer of hexafluoropropylene and vinylidene fluoride, copolymer of tetrafluoroethylene-perfluoroalkyl vinyl ether , At least one of the group consisting of polytrifluoroethylene, polyvinyl chloride, tetrafluoroethylene-hexafluoropropylene copolymer, ethylene-fluoroethylene copolymer, and tetrafluoroethylene-hexafluoropropylene-trifluoroethylene copolymer . The double-sided copper foil substrate having a fluorine-based polymer and having high frequency and high transmission characteristics as described in item 1 of the scope of the patent application, wherein the water absorption of the double-sided copper foil substrate is 0.01 to 0.10%. The double-sided copper foil substrate having a fluorine-based polymer and high frequency and high transmission characteristics as described in item 1 of the scope of the patent application, wherein the first copper foil layer, the first insulating polymer layer, and the first electrode The adhesion strength between the low-dielectric adhesive layer, the core layer, the second extremely low-dielectric adhesive layer, the second insulating polymer layer, and the second copper foil layer was all greater than 0.8 kgf / cm. The double-sided copper foil substrate with fluorine-based polymer and high-frequency and high-transmission characteristics according to item 1 of the scope of the patent application, wherein the first extremely low-dielectric adhesive layer and the second extremely low-dielectric adhesive layer The resin material is independently selected from fluorine resins, epoxy resins, acrylic resins, urethane resins, silicone rubber resins, parylene resins, bismaleimide resins and polymers. At least one of the group consisting of fluorene imine resin. The double-sided copper foil substrate with fluorine-based polymer and high-frequency and high-transmission characteristics according to item 1 of the scope of the patent application, wherein the first extremely low-dielectric adhesive layer and the second extremely low-dielectric adhesive layer It is a thermosetting polyimide layer containing polyimide. The double-sided copper foil substrate having a fluorine-based polymer and high frequency and high transmission characteristics as described in item 6 of the scope of patent application, wherein the polyimide content in the first extremely low dielectric adhesive layer is the first 40 to 95% by weight of the total solid content of a very low dielectric adhesive layer, and the polyimide content in the second extremely low dielectric adhesive layer is based on the weight of the total solid content of the second extremely low dielectric adhesive layer 40 to 95%. The double-sided copper foil substrate with a fluorine-based polymer and high-frequency and high-transmission characteristics as described in item 1 of the scope of the patent application, wherein the fluorine-based polymer in the first insulating polymer layer accounts for the weight of its total solid content When it is 60% to less than 80%, its water absorption is 0.5 to 0.6%, the dielectric constant is 3.5, and the dielectric loss is 0.009; and the fluorine-based polymer in the second insulating polymer layer accounts for its total solid content. When the weight is 60% to less than 80%, the water absorption is 0.5 to 0.6%, the dielectric constant is 3.5, and the dielectric loss is 0.009. The double-sided copper foil substrate with a fluorine-based polymer and high-frequency and high-transmission characteristics as described in item 1 of the scope of the patent application, wherein the fluorine-based polymer in the first insulating polymer layer accounts for the weight of its total solid content From 80% to less than 90%, the water absorption rate is 0.1 to 0.2%, the dielectric constant is 3.2, and the dielectric loss is 0.005, and the fluorine-based polymer in the second insulating polymer layer accounts for its total solid content. When the weight is 80% to less than 90%, the water absorption is 0.1 to 0.2%, the dielectric constant is 3.2, and the dielectric loss is 0.005. The double-sided copper foil substrate with a fluorine-based polymer and high-frequency and high-transmission characteristics as described in item 1 of the scope of the patent application, wherein the fluorine-based polymer in the first insulating polymer layer accounts for the weight of its total solid content When it is 90% to less than 100%, its water absorption is 0.01 to 0.02%, its dielectric constant is 3.0, and its dielectric loss is 0.003, and the fluorine-based polymer in the second insulating polymer layer accounts for its total solid content. When the weight is 90% to less than 100%, the water absorption is 0.01 to 0.02%, the dielectric constant is 3.0, and the dielectric loss is 0.003. A composite material for a flexible printed circuit board (FPC), comprising: a double-sided copper foil substrate as described in item 1 of the scope of patent application; and an adhesive-backed flexible copper foil substrate (FRCC) including a third copper foil Layer, a polyimide layer and a third ultra-low dielectric adhesive layer sequentially formed on the surface of the third copper foil layer, and the adhesive-backed flexible copper foil substrate is based on the third ultra-low dielectric adhesive layer The first copper foil layer laminated on the double-sided copper foil substrate. The composite material for a flexible printed circuit board (FPC) according to item 11 of the scope of patent application, wherein the surface roughness (Rz value) of the surface of the third copper foil layer in contact with the polyimide layer It is 0.1 to 1.0 micrometer. A method for preparing a double-sided copper foil substrate with a fluorine-based polymer and high frequency and high transmission characteristics, comprising: coating a fluorine-based polymer on a surface of a first copper foil layer, and removing the same at 60 to 100 ° C. Solvent in the fluorine-based polymer to form a first insulating polymer layer; apply a fluorine-based polymer on the surface of the second copper foil layer, and remove the solvent in the fluorine-based polymer at 60 to 100 ° C to Forming a second insulating polymer layer; coating an extremely low dielectric adhesive on two opposite surfaces of the polyimide layer, and drying the extremely low dielectric adhesive at 60 to 100 ° C to form a first extremely low dielectric An adhesive layer and a second extremely low-dielectric adhesive layer; the first insulating polymer is laminated and laminated under the conditions of a pressing pressure of 1 to 5 kgf / cm² and a pressing temperature of 100 to 160 ° C. Laminating the second insulating polymer on the surface of the first extremely low dielectric adhesive layer; and reacting for 0.5 to 1.5 hours at a temperature of 190 to 210 ° C , Rewinding and heating to form a composite fluorine polymer high frequency and high transmission double-sided copper foil substrate. A method for preparing a double-sided copper foil substrate with a fluorine-based polymer and high-frequency and high-transmission characteristics. The method includes: using a double-layer coating technique on the surface of the first copper foil layer to combine the fluorine-based polymer and a very low dielectric An electric adhesive is coated on the first copper foil layer at the same time, and the solvent is removed at 60 to 100 ° C. to sequentially form a first insulating polymer layer and a first extremely low-dielectric adhesive on the first copper foil layer; On the surface of the second copper foil layer, a fluoropolymer and an extremely low dielectric adhesive are simultaneously coated on the second copper foil layer by a double-layer coating technique, and the solvent is removed at 60 to 100 ° C. for the second A second insulating polymer layer and a second extremely low dielectric adhesive layer are sequentially formed on the copper foil layer; under the conditions of a pressing pressure of 1 to 5 kgf / cm² and a pressing temperature of 100 to 160 ° C, The first extremely low-dielectric adhesive layer and the second extremely low-dielectric adhesive layer are laminated on opposite surfaces of the polyimide layer; and the reaction is carried out at a temperature of 190 to 210 ° C for 0.5 to 1.5 hours, and the roll is rolled. Heated to form a composite fluoropolymer high frequency and high transmission double-sided copper foil substrate.