Manufacturing method of flexible copper-clad laminate with PTFE substrate

Abstract

The present invention relates to a method for manufacturing a flexible copper-clad laminate of a PTFE substrate. More specifically, the present invention relates to a method for manufacturing a flexible copper-clad laminate (FCCL) by uniformly depositing a metal thin film on a PTFE substrate to improve the electrical performance of the flexible copper-clad laminate and prevent deterioration of the physical properties of the PTFE substrate.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a flexible copper-clad laminate on a PTFE substrate. More specifically, the present invention relates to a method for manufacturing a flexible copper-clad laminate (FCCL) by uniformly depositing a metal thin film on a PTFE substrate, which can improve the electrical performance of the flexible copper-clad laminate and prevent the deterioration of the physical properties of the PTFE substrate.

Background Art

[0002] A flexible copper-clad laminate (FCCL) is a core material of a flexible printed circuit board (FPCB) mainly used in smartphones, PCs, semiconductors, automotive electrics, displays, mobility, secondary batteries, etc. Generally, a flexible copper-clad laminate (FCCL) is a product in which a metal thin film is laminated on both sides or one side of a polymer substrate.

[0003] As the substrate constituting the flexible copper-clad laminate (FCCL), various insulating materials such as polyimide (PI) resin, thermoplastic resin, glass, epoxy resin, and liquid crystal polymer (LCP) can be applied. Preferably, a polytetrafluoroethylene (PTFE) material having excellent mechanical and electrical properties can be applied.

[0004] Polytetrafluoroethylene (hereinafter referred to as "PTFE") materials are excellent in mechanical properties such as chemical resistance, heat resistance, and dimensional safety, and have a low dielectric constant and dielectric loss compared to other insulating materials. Therefore, when applied to printed circuit boards (PCBs), there is an advantage that the signal and data transmission speed is faster in the same antenna circuit. On the other hand, since PTFE has a poor metal bonding force compared to other insulating materials, a method for compensating the bonding force between the PTFE substrate and the metal is required.

[0005] FIG. 1 shows various manufacturing methods of a conventional flexible copper-clad laminate (FCCL).

[0006] In the manufacture of a flexible copper-clad laminate (FCCL), among various manufacturing process methods for bonding a substrate and a copper thin film, the laminating process shown in FIG. 1(a) is a method of applying an adhesive 30 to one or both sides of a PTFE substrate 10 and bonding a copper thin film 20. The casting process shown in FIG. 1(b) is a method of casting an insulating resin 40 solution in which polyimide (PI) and PTFE are mixed on the copper thin film 20 and bonding a substrate made of the insulating resin 40 to the copper thin film 20. The coating process shown in FIG. 1(c) is a method of impregnating a PTFE substrate 10 with polyimide (PI) and then plating or coating a copper melt 50 on the impregnated PTFE substrate 10 to bond a copper thin film 20.

[0007] As shown in FIG. 1, since the manufacturing method of the conventional flexible copper-clad laminate (FCCL) uses an adhesive or polyimide (PI), there is a problem that the dielectric constant of the flexible copper-clad laminate (FCCL) increases and the signal and data transmission speed becomes slow compared to the case where the PTFE substrate 10 is used alone.

[0008] Therefore, there has been a proposal of a sputtering process that can prevent problems such as a decrease in the transmission speed of a flexible copper-clad laminate (FCCL) due to the use of an adhesive or PI as in the conventional case by directly depositing a copper thin film on the PTFE substrate 10.

[0009] The sputtering process is a type of physical vapor deposition method mainly used in the production of integrated circuits. In this process, ionized gas at a relatively low vacuum level is accelerated and collided with a target, causing atoms to eject and form a thin film on a substrate. Such a sputtering process is important to control so that metal particles forming the thin film are uniformly deposited on the substrate in order to remove electrical noise and physical vibrations.

[0010] Among related prior arts, Korean Patent Publication No. 10-2022-0049366 discloses a sputtering apparatus for uniformly growing a metal thin film on a substrate by controlling particles emitted from a target in atomic layer units.

[0011] On the other hand, as a result of forming a metal thin film on substrates to which various materials are applied using the sputtering apparatus according to the prior art, the metal thin film was uniformly formed on substrates having a crystalline structure such as sapphire (aluminum oxide). However, on substrates made of PTFE material, it was not easy to control the atomic layer, and the metal thin film could not be uniformly formed. There was also a problem that the physical properties of the PTFE substrate were damaged or deformed during the deposition process, resulting in a decrease in the quality of the flexible copper-clad laminate (FCCL).

[0012] Recently, despite the rapid increase in the demand for flexible copper-clad laminates (FCCLs) with the development of advanced industries such as communication, display, semiconductors, and secondary batteries, the fact is that there is almost no technology capable of uniformly depositing a metal thin film on a PTFE substrate widely applied as a substrate material for FCCLs.

[0013] Therefore, in order to manufacture a flexible copper clad laminate (FCCL), while omitting the use of adhesives or resins such as polyimide (PI) as in the prior art, by uniformly depositing a metal thin film on a PTFE substrate, it is urgently required to develop a method for manufacturing a flexible copper clad laminate of a PTFE substrate that can improve the electrical performance of the flexible copper clad laminate (FCCL) and prevent deterioration of the physical properties of the PTFE substrate.

Summary of the Invention

Problems to be Solved by the Invention

[0014] An object of the present invention is to provide a method for manufacturing a flexible copper clad laminate of a PTFE substrate that can improve the electrical performance of the flexible copper clad laminate (FCCL) and prevent deterioration of the physical properties of the PTFE substrate by uniformly depositing a metal thin film on the PTFE substrate in order to manufacture the flexible copper clad laminate (FCCL).

Means for Solving the Problems

[0015] To solve the above problems, the present invention provides a method for manufacturing a flexible copper clad laminate of a PTFE substrate, comprising: a PTFE substrate preparation step of preparing a substrate made of a PTFE (Polytetrafluoroethylene) material in a chamber space of a vacuum chamber; a reaction gas injection step of evacuating the chamber space of the vacuum chamber and then injecting a reaction gas for a sputtering process; a high-frequency power application step of applying high-frequency power to a target made of single-crystalline metal particles mounted on the upper inner part of the vacuum chamber; and a metal thin film deposition step of depositing metal particles separated from the target by the applied high-frequency power on the PTFE substrate to form a metal thin film.

[0016] Also, the temperature of the chamber space of the vacuum chamber for preparing the PTFE substrate in the PTFE substrate preparation stage can be formed in the range of 140 degrees (°C) to 200 degrees (°C).

[0017] And, the gas injected into the chamber space of the vacuum chamber in the reaction gas injection stage can contain argon (Ar).

[0018] In this case, in the high-frequency power application stage, the high-frequency power can be transmitted to the target mounted on the inner upper end of the vacuum chamber via a power supply line made of single-crystal copper wire.

[0019] In this case, in the metal thin film lamination stage, the metal thin film can be deposited on the PTFE substrate by an atomic sputtering epitaxy (ASE) process of laminating metal particles of atomic units on the PTFE.

[0020] Also, in the metal thin film lamination stage, the metal thin film can be laminated on the PTFE substrate in the range of 100 to 300 nm in thickness.

[0021] And, in the metal thin film lamination stage, the metal particles can contain copper (Cu).

[0022] Here, vibrations transmitted to the vacuum chamber can be absorbed or blocked while metal particles separated from the target are deposited on the PTFE substrate in the metal thin film lamination stage.

[0023] Also, a metal thin film pattern formation stage of forming a pattern having a specific shape on the surface of the metal thin film laminated on the PTFE substrate can be further executed.

[0024] And, the pattern formed in the metal thin film pattern formation stage can have a hexagonal honeycomb shape with a line width of 5 μm to 14 μm.

Advantages of the Invention

[0025] According to the manufacturing method of the flexible copper-clad laminate of the PTFE substrate according to the present invention, by using an Atomic Sputtering epitaxy (ASE) process to improve the bonding strength between the PTFE substrate and the metal thin film, and depositing the metal thin film uniformly on the PTFE substrate, the electrical performance of the flexible copper-clad laminate can be improved, and it has excellent heat resistance and mechanical properties, and can be applied as a cutting-edge material used in various industrial fields such as communication, semiconductor, display, and secondary battery.

Brief Description of Drawings

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DETAILED DESCRIPTION OF THE INVENTION

[0027] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described herein and can be embodied in other forms. Rather, the embodiments introduced here are provided so that the disclosure is thorough and complete, and to fully convey the idea of the present invention to those skilled in the art. The same reference numerals denote the same components throughout the specification.

[0028] According to the method for manufacturing a flexible copper-clad laminate of a PTFE substrate according to the present invention, the bonding strength between the PTFE substrate and the metal thin film is improved using an Atomic Sputtering epitaxy (ASE) process, and the metal thin film is uniformly deposited on the PTFE substrate. With reference to FIG. 2, the Atomic Sputtering epitaxy (ASE) process used in the present invention will be described.

[0029] Figure 2 shows the initial growth mechanism of the metal thin film 20 deposited on the sapphire (Al2O3) substrate 10s by the Atomic Sputtering epitaxy (ASE) process.

[0030] As shown in Figure 2, the initial growth mechanism of the metal thin film 20 generally consists of three stages: (I) to (III). Specifically, stage (I) is the stage where the ejected metal particles 21 grow into the shape of nano-droplets, stage (II) is the stage where the metal particles 21 in the shape of nano-droplets integrate with each other, and stage (III) is the stage where the metal particles 21 grow into multiple layers.

[0031] In a general sputtering process, a polycrystalline metal thin film 20 is deposited on the sapphire substrate 10s so that grain boundaries are formed in the polycrystalline metal thin film 20. A grain boundary is a thin transition layer that forms the boundary between crystals. In the crystal growth process, this vicinity finally solidifies and contains impurities or oxygen atoms bond to form copper oxide. Therefore, the general sputtering process has a problem that the copper thin film 20 cannot grow epitaxially on the sapphire substrate 10s.

[0032] Therefore, by performing the Atomic Sputtering epitaxy (ASE) process to realize an ultra-flat copper thin film 20 of about a single atomic layer on the sapphire substrate 10s, copper oxidation can be prevented.

[0033] On the other hand, in a general sputtering process, metal particles 21 are ejected in a solid state from the target material and deposited on the deposition surface, while the Atomic Sputtering epitaxy (ASE) process is a thin film growth method in which atoms are stacked one by one on the deposition surface like building bricks. Hereinafter, the Atomic Sputtering epitaxy (ASE) process will be described in more detail.

[0034] Generally, copper (Cu) is the most widely used conductor in the electrical civilization. However, since the fatal weakness of oxidation limits the use of copper, gold, a precious metal that is much more expensive despite having worse electrical conductivity than copper, has been used in ultra-precise materials or circuits that require high reliability. Although various studies on copper oxidation have been conducted, only the description of the phenomenological state or theoretical predictions have been reported. As the material becomes smaller and more highly integrated, ensuring sufficient usage time and miniaturizing the power supply unit become important, so a material with high conductivity is required. Against this background, the problem of copper oxidation on the sapphire substrate 10s can be solved by performing the Atomic Sputtering epitaxy (ASE) process.

[0035] Since it is empirically known that oxidation progresses from the rough parts of copper, it is most important to make a thin film with the best possible surface condition. Therefore, using the Atomic Sputtering epitaxy (ASE) process method, a thin film with an ultra-flat surface of about one atomic layer can be grown on the sapphire substrate 10s.

[0036] The metal thin film 20 manufactured on the sapphire substrate 10s forms an ultra-flat surface with an RMS roughness of 0.2 nm or less while being in a single crystal state and does not oxidize even when exposed to air for a long time. According to the observation by a high-resolution transmission electron microscope, if the surface is maintained at a roughness of less than one atomic layer, the phase transition due to oxidation does not occur. As a result of calculating the oxygen penetration energy according to the surface state by first-principles calculation, when the surface is maintained at a roughness of less than one atomic layer, energy must be supplied from the outside for oxygen to penetrate into the metal thin film 20, so oxidation does not easily occur. Also, when the oxygen occupancy of the physically adsorbed surface without chemical bonding exceeds 50%, there is a self-regulating function that generates a repulsive force and suppresses oxidation by itself.

[0037] Thus, by performing the Atomic Sputtering Epitaxy (ASE) process, the impact of copper oxidation on the materials industry is very significant and can be applied to many areas where existing gold (Au) is to be replaced with copper. In particular, with the development of nanoscience, as the circuit linewidth decreases and the integration density increases, the oxidation of thin conductive lines becomes a more serious problem. On the other hand, ultra-flat single-crystal thin films do not have to worry about the oxidation problem, so the scope of application is very wide. Economically, it can provide an opportunity for copper thin films to completely replace the gold used in nano-circuits and the like. The electrical conductivity of copper is about 40% better than that of gold, and furthermore, when it becomes a single-crystal copper thin film with an ultra-flat surface, it can be increased by more than 15% compared to the conductivity of general copper. Therefore, its economic added value is very high in terms of reducing power consumption and energy, extending the usage time, and miniaturizing equipment.

[0038] On the other hand, although there has been an introduction of a technique for depositing a metal thin film 20 such as a copper thin film on a sapphire (aluminum oxide, Al2O3) substrate 10s by performing such an Atomic Sputtering Epitaxy (ASE) process, there has been no introduction of a technique for uniformly depositing a copper thin film on a PTFE substrate 10 by applying such an Atomic Sputtering Epitaxy (ASE) process.

[0039] Polytetrafluoroethylene (PTFE) has sufficient mechanical properties and excellent low dielectric characteristics. In particular, when the PTFE material is applied to the substrate of a Flexible copper clad laminate (FCCL), it can reduce data loss and improve the transmission speed. Therefore, it is one of the recently spotlighted materials.

[0040] However, when performing an Atomic Sputtering epitaxy (ASE) process to deposit a copper thin film on the PTFE substrate 10, unlike a crystalline substrate made of aluminum oxide (Al2O3) or the like, the PTFE material is a polymer material that is relatively weak against environmental variables such as temperature and pressure. Therefore, there are process difficulties such as the physical properties being easily changed during the deposition process and the quality of the FCCL being degraded.

[0041] Also, when performing an Atomic Sputtering epitaxy (ASE) process to deposit a copper thin film on the PTFE substrate 10, unlike a crystalline substrate such as the sapphire substrate 10s, there is a problem that the adsorption energy is insufficient between the PTFE substrate 10 and the copper thin film, and the copper thin film easily desorbs from the PTFE substrate 10, resulting in a decrease in electrical conductivity.

[0042] Therefore, the present invention applies the conventionally introduced Atomic Sputtering epitaxy (ASE) process and improves the deposition conditions according to the substrate material, so that even on the PTFE substrate 10, it is easy to deposit a uniform metal thin film 20, which is excellent in the electrical performance of the flexible copper-clad laminate (FCCL), and the adsorptivity can be improved at the interface between the PTFE substrate 10 and the metal thin film 20.

[0043] FIG. 3 is a flowchart showing the steps of a method for manufacturing a flexible copper-clad laminate of a PTFE substrate according to the present invention.

[0044] As shown in Fig. 3, the method for manufacturing a flexible copper-clad laminate of a PTFE substrate according to the present invention can include a PTFE substrate preparation step (S100) of preparing a substrate made of a PTFE (Polytetrafluoroethylene) material in the chamber space of a vacuum chamber, a reaction gas injection step (S200) of injecting a reaction gas after forming the chamber space of the vacuum chamber into a vacuum for a sputtering process, a high-frequency power application step (S300) of applying high-frequency power to a target made of single-crystalline metal particles mounted on the inner upper end of the vacuum chamber, and a metal thin film deposition step (S400) of depositing metal particles separated from the target onto the PTFE substrate 10 by the applied high-frequency power to laminate a metal thin film 20.

[0045] In the manufacture of a flexible copper-clad laminate (FCCL), the present invention provides a method for manufacturing a flexible copper-clad laminate of a PTFE substrate capable of controlling a high-quality metal thin film 20 by applying an atomic sputtering epitaxy (ASE) process to control the crystal structure of the metal thin film 20 in atomic layer units on the PTFE substrate 10 constituting the flexible copper-clad laminate (FCCL).

[0046] The sputtering apparatus used in the method for manufacturing a flexible copper-clad laminate of a PTFE substrate according to the present invention shown in Fig. 3 is an apparatus that removes noise of a target substance, electrical noise, and mechanical noise in a general sputtering apparatus and can execute the above-described atomic sputtering epitaxy (ASE) process.

[0047] The method for manufacturing a flexible copper-clad laminate of a PTFE substrate according to the present invention can be executed by a sputtering apparatus including a vacuum chamber, an RF generation unit, a vacuum pump unit, a gas supply unit, and a vibration isolation unit.

[0048] First, a PTFE substrate preparation step (S100) of preparing a substrate made of a PTFE (Polytetrafluoroethylene) material in the chamber space of a vacuum chamber can be executed.

[0049] Here, the vacuum chamber is a space where a sputtering process of depositing a metal thin film 20 on the PTFE substrate 10 is executed. The vacuum chamber includes a PTFE substrate, a target, and a chamber space. The PTFE substrate 10 is the anode part in the sputtering process and can be made of a polytetrafluoroethylene (PTFE) material. A target is located at the cathode part facing the PTFE substrate 10, and the target is formed of the metal substance of the thin film to be deposited on the PTFE substrate 10. Such a PTFE substrate 10 and target are located inside the chamber space, and the metal thin film 20 is manufactured by the particles separated from the target being deposited on the PTFE substrate 10 by the subsequent sputtering process.

[0050] In the PTFE substrate preparation step (S100), the chamber space temperature of the vacuum chamber where the PTFE substrate 10 is provided can be formed and maintained in the range of 140 degrees (°C) to 200 degrees (°C), preferably in the range of 150 degrees to 170 degrees (°C). When the internal temperature of the chamber space is less than 140 degrees (°C), the metal thin film 20 deposited on the PTFE substrate 10 cannot be formed uniformly, while when it exceeds 200 degrees (°C), there is a problem that the physical properties of the PTFE substrate 10 change.

[0051] Also, in the manufacturing method of the flexible copper-clad laminate of the PTFE substrate according to the present invention, the pressure condition or vacuum condition inside the chamber space can be optimized by repeated experiments so that the crystals of the metal thin film 20 can grow uniformly on the PTFE substrate 10. Further, by pre-treating the PTFE substrate 10, the metal thin film 20 can grow with high adsorptivity at the interface of the PTFE substrate 10.

[0052] Next, the reaction gas injection step (S200) and the high-frequency power application step (S300) of the present invention can be sequentially executed.

[0053] The reaction gas injection step (S200) is a step of injecting a reaction gas after forming a vacuum in the chamber space of the vacuum chamber for the sputtering process. The high-frequency power application step (S300) is a step of applying high-frequency power to a target made of single-crystalline metal particles, which is mounted on the upper inner part of the vacuum chamber.

[0054] The reaction gas injection step (S200) and the high-frequency power application step (S300) can be executed by a gas supply unit and an RF generation unit that constitute a sputtering apparatus, respectively.

[0055] The RF generation unit for executing the high-frequency power application step (S300) is configured to apply RF power, which is high-frequency power, to the target of the vacuum chamber for the sputtering process, and is connected to the target by a connecting wire.

[0056] On the other hand, for the sputtering process, the chamber space must be in a vacuum state. The vacuum pump unit that constitutes the sputtering apparatus is configured to suck the fluid inside the chamber space so as to form a vacuum inside the chamber space of the vacuum chamber, and can be a generally used rotary pump.

[0057] For this purpose, a gas supply unit that supplies a reaction gas for the sputtering process is connected to the chamber space of the vacuum chamber inside the vacuum chamber space. The reaction gas supplied by the gas supply unit is argon (Ar) gas. The higher the purity of the argon gas, the more uniformly the deposition particles are separated from the target on the entire surface of the target, and the metal thin film deposition step (S400) can be executed.

[0058] The metal thin film deposition step (S400) has the configuration of the sputtering apparatus described above. When RF power is applied to the target in the chamber space where the reaction gas is supplied in a vacuum state by the RF generator, the reaction gas is ionized by glow discharge, and plasma discharge occurs between the PTFE substrate 10 and the target. The cations present in the discharge region strike the surface of the target by the electrical power, and the vapor deposition particles separated from the surface of the target are deposited on the facing PTFE substrate 10, thereby manufacturing the metal thin film 20.

[0059] On the other hand, in the execution of the high-frequency power application step (S300) of the present invention, the power cable for supplying power to the RF generator is formed of a single crystal copper wire. As a result, the signal transmitted to the power cable is not mixed with noise and signal distortion, the safety of the RF power applied to the target is increased, and the deposition particles are uniformly separated from the entire surface of the target, so that the quality of the metal thin film 20 deposited on the PTFE substrate 10 can be improved.

[0060] And the homogeneity of the deposition particles separated from the target is related to the crystallinity of the target in terms of the deposition particles being separated from the target. Therefore, the target contained in the vacuum chamber can be formed of single crystal metal. Thus, when the target is formed of single crystal metal, metal particles are uniformly formed on the entire surface of the target with a certain directionality, so that the deposition particles separated therefrom are also homogeneous and the metal thin film 20 to be deposited can be manufactured with high quality. The type of single crystal metal forming the target is determined by the type of the metal thin film 20 to be deposited on the PTFE substrate 10, and can be copper, silver, or a single-element metal.

[0061] Also, when executing the high-frequency power application stage (S300), the connecting wire for transmitting the RF power of the RF generation unit to the target in the vacuum chamber can also be formed of single-crystal copper wire. Therefore, electrical noise can be removed from the RF power applied to the target, enhancing the safety of the power, thereby enhancing the homogeneity of the plasma discharge formed between the PTFE substrate 10 and the target, and enabling the deposition particles to be uniformly desorbed from the entire surface of the target.

[0062] The outdoor grounding part formed for grounding the RF generation unit can be formed of single-crystal copper bulk. The single-crystal copper constituting the outdoor grounding part can be manufactured together with the target when the metal type of the target is copper. Thus, when the outdoor grounding part is formed of single-crystal copper bulk, the safety of the RF power can be enhanced, so that the deposition particles can be uniformly separated.

[0063] In addition, the present invention can grow the metal thin film 20 to have high adsorptivity at the interface with the PTFE thin film by preventing mechanical noise, such as vibration, from being applied during the process in which the deposition particles separated from the target are deposited on the PTFE substrate 10 in the metal thin film lamination stage (S400).

[0064] For this purpose, the vacuum chamber can be supported at each corner of the bottom surface by a vibration isolation part so that vibration from the bottom is not transmitted. The vibration isolation part has a mechanical irreversible structure in which vibration from the bottom is not transmitted to the vacuum chamber, and conversely, vibration generated in the vacuum chamber is discharged to the outside (bottom) and offset.

[0065] Specifically, in the metal thin film lamination step (S400), the vibration blocking portion for blocking vibrations transmitted to the vacuum chamber includes spikes and a damping mat. The spikes are configured to adhere to the bottom surface of the vacuum chamber to support the vacuum chamber and have a conical shape that becomes sharper towards the bottom. The damping mat is seated on the bottom and is configured to accommodate the spikes on its upper surface. Insertion grooves for accommodating the tips of the spikes are formed on the upper surface of the damping mat, and by accommodating the spikes in the insertion grooves of the damping mat, the planar position of the spikes is fixed.

[0066] With such a vibration blocking portion including spikes and a damping mat, vibrations generated from the bottom only vibrate the damping mat and cannot apply force to the spikes, so they are not transmitted to the vacuum chamber supported by the spikes. As a result, the vacuum chamber is not affected by the vibrations of the bottom, and no physical external force is transmitted during the process in which the vapor deposition particles separated from the target are vapor deposited on the PTFE substrate 10. Therefore, the metal thin film 20 can be vapor deposited uniformly on the PTFE substrate 10 to improve the quality of the metal thin film 20. On the other hand, since it is sufficient for the spikes to be conical, they can have various shapes such as a circular cone shape, a triangular pyramid shape, a square pyramid shape, etc.

[0067] And, in order to more effectively block physical vibrations to the vacuum chamber, the sputtering apparatus used for the method of manufacturing the flexible copper-clad laminate of the PTFE substrate of the present invention can physically separate the vacuum chamber and the vacuum pump section.

[0068] A rotary pump, which is an example of the vacuum pump section, generates a lot of vibrations due to the operation of the pump during the process of sucking fluid so as to evacuate the chamber space of the vacuum chamber. When the vacuum chamber and the vacuum pump section are physically configured together, the vibrations generated during the operation of the vacuum pump section are directly transmitted to the vacuum chamber, so that the vapor deposition particles deposited on the PTFE substrate 10 are not formed uniformly.

[0069] Therefore, in order to physically separate the vacuum pump section from the vacuum chamber, connect it to the chamber with a pump line made of rubber material, and also block the transmission of the vibration of the pump line to the vacuum chamber, the pump line can fix its center to the wall surface connected to the bottom.

[0070] On the other hand, when the vacuum pump section is physically separated from the vacuum chamber, since it is also necessary to block such a vacuum pump section itself from vibration, similar to the vacuum chamber, each corner of the bottom surface can be supported by a vibration isolation section so that vibration from the bottom is not transmitted.

[0071] Figure 4(a) is an image obtained by observing a pure PTFE substrate without copper lamination with a scanning electron microscope (SEM), and Figure 4(b) is an image obtained by observing a PTFE substrate with copper lamination with an SEM.

[0072] On the other hand, as shown in Figure 4(a), it is not easy to observe the PTFE surface with a scanning electron microscope (SEM) due to electron charging. However, when observed at magnifications of 500 times and 5000 times, it was confirmed that the surface was rough and uneven. As shown in Figure 4(b), if a copper thin film with a thickness of 200 nm is deposited on the PTFE substrate 10 by an atomic sputtering epitaxy (ASE) process using the above-described sputtering apparatus, it can be seen that the deposition is very uniform while maintaining the original shape of the PTFE.

[0073] Figure 5 is an image obtained by observing the copper surface deposited on PTFE with electron backscatter diffraction (EBSD).

[0074] As shown in Fig. 5, when observing a map of the copper surface vapor-deposited to a thickness of 200 nm on PTFE using electron beam scatter diffraction (EBSD), it can be seen that all the copper crystal grains are arranged in different directions respectively.

[0075] Figs. 5(b) and 5(c) show the inverse pole figure (IPF) and pole figure (PF) of the particle surface points measured in the directions of different crystal axes respectively, and it can be seen that the directions of the crystals are very diverse.

[0076] Fig. 5(d) shows the IQ image of the misorientation map indicating the boundary lines between crystal grains, and it appears entirely in blue such that no misorientation lines can be seen. Here, the red line is exactly the line that satisfies the conditions of the twin boundary, and the blue line indicates the grain boundary in an arbitrary direction that does not satisfy specific conditions. The fact that there are almost no red lines and only blue lines means that the particles are oriented in very diverse directions.

[0077] If the image shown in Fig. 5(d) is enlarged, as shown in Fig. 5(e), particles (scale bar: 100 nm) can be seen, and it can be observed that their sizes are overall very uniform and closely arranged, and the maximum size of the particles corresponds to about 10 nm. Such a small particle size minimizes the atomic spacing at the grain boundary and the gaps, thereby reducing the space for oxygen and external impurities to enter and minimizing the progress of oxidation despite being polycrystalline, resulting in the effect of preventing the formation of copper oxide.

[0078] The method for manufacturing a flexible copper-clad laminate of a PTFE substrate according to the present invention can further execute a metal thin film pattern forming step (S500) of forming a pattern p having a specific shape on the surface of the metal thin film 20 laminated on the PTFE substrate 10.

[0079] Figure 6 is a photograph of a mesh and a circuit image obtained by patterning a copper thin film deposited on a PTFE substrate in the method for manufacturing a flexible copper-clad laminate of a PTFE substrate according to the present invention.

[0080] Figures 6(b) and 6(c) show an enlarged hexagonal honeycomb mesh image obtained by patterning a copper thin film deposited on a PTFE substrate 10 in the method for manufacturing a flexible copper-clad laminate of a PTFE substrate according to the present invention by a photolithography process. The images shown in Figures 6(b) and 6(c) were respectively taken at magnifications of 40 and 250 using a transmission polarizing microscope.

[0081] Figure 6(d) shows a circuit image obtained by patterning a copper thin film deposited on a PTFE substrate 10 in the method for manufacturing a flexible copper-clad laminate of a PTFE substrate according to the present invention by a photolithography process.

[0082] As shown in Figure 6(a), a hexagonal honeycomb mesh pattern p can be formed on a copper thin film deposited on an e-PTFE substrate. The mesh pattern p can achieve electrical connection using the copper thin film in products such as electronic devices and solar cells, and can strengthen the surface of the copper thin film to enhance durability. The mesh pattern p can be formed by opening holes at regular intervals on the surface of the copper thin film and connecting copper wires inside.

[0083] The line width of the mesh pattern p formed in the metal thin film pattern formation step (S500) is determined by the interval between the holes formed in the copper thin film, and the electrical resistance decreases as the line width decreases. The open area of the mesh pattern means the ratio of the area occupied by the holes in the mesh pattern, and the larger the open area, the easier the current flows and the more effectively electrical connection can be achieved.

[0084] The line width and open area of such a mesh pattern p can be appropriately selected according to the electrical performance and manufacturing cost required for a flexible copper-clad laminate (FCCL) or the like. In the embodiment shown in FIG. 6(a), it was confirmed that the mesh pattern p of the copper thin film deposited on the e-PTFE substrate has a line width of about 10 μm and an open area of about 50 μm.

[0085] The mesh pattern of the copper thin film is a type of printed circuit board (PCB) used in electronic circuits, and a desired circuit pattern can be formed as shown in FIG. 6(b) using a PTFE substrate 10 on which a copper thin film is deposited for electrical connection.

[0086] Thus, in the method for manufacturing a flexible copper-clad laminate of a PTFE substrate according to the present invention, during the sputtering process, process variables such as environmental variables, for example, the temperature, pressure, and degree of vacuum inside the chamber space, are adjusted, the deposition conditions optimized for the PTFE substrate 10 are specified, and the pretreatment process of the PTFE substrate 10 is performed, so that even on a PTFE substrate 10 that is not an existing crystalline substrate, an atomic sputtering epitaxy (ASE) process can be performed to uniformly deposit a metal thin film 20.

[0087] Specifically, as a result of performing an atomic sputtering epitaxy (ASE) process in the method for manufacturing a flexible copper-clad laminate of a PTFE substrate according to the present invention, the crystal growth rate of the copper thin film is about 10 nm / min or more, the particle size is very uniform at about 10 to 15 nm, voids and stacking defects due to grain boundaries are minimized, and the surface roughness is about 0.5 nm.

[0088] FIG. 7 shows an image of the X-ray diffraction experiment results of a Cu / e-PTFE thin film on which 300 nm of Cu is deposited by the method for manufacturing a flexible copper-clad laminate of a PTFE substrate according to the present invention.

[0089] As shown in Fig. 7, there are a plurality of e-PTFE diffraction peaks ▽ and copper diffraction peaks on the X-ray diffraction experiment result image of the Cu / e-PTFE thin film. Also, it can be seen that there are diffraction peaks in multiple directions on the said image, and it can be understood that both substances (e-PTFE, Cu) exist in a polycrystalline state. On the other hand, although there are also particles (grains) corresponding to the (100) and (110) orientations, it was confirmed that the orientation in the Cu(111) direction is mainly the most developed.

[0090] Fig. 8 shows the AFM surface image of the Cu / e-PTFE thin film manufactured using the manufacturing method of the flexible copper-clad laminate of the PTFE substrate according to the present invention. From the AFM surface image of the Cu / e-PTFE thin film shown in Fig. 8, it was confirmed that the RMS roughness is about 90.4 nm.

[0091] Fig. 9 shows another example of the AFM surface image of the Cu / e-PTFE thin film manufactured by the manufacturing method of the flexible copper-clad laminate of the PTFE substrate according to the present invention.

[0092] Specifically, the AFM surface image of the Cu / e-PTFE thin film shown in Fig. 9 is the result of measurement with the measurement range reduced to 10 μm 2 (10 μm × 10 μm) in Fig. 8. From the AFM surface image of the Cu / e-PTFE thin film shown in Fig. 9, it was confirmed that the RMS roughness decreases to about 29.2 nm as a result of measurement excluding the defective parts of e-PTFE.

[0093] Fig. 10 shows yet another example of the AFM surface image of the Cu / e-PTFE thin film manufactured by the manufacturing method of the flexible copper-clad laminate of the PTFE substrate according to the present invention.

[0094] Specifically, the AFM surface image of the Cu / e-PTFE thin film shown in Fig. 10 is the result of measurement with the measurement range reduced to 1 μm 2This is the result of measurement after reducing it to (1 μm × 1 μm). From the AFM surface image of the Cu / e-PTFE thin film shown in Fig. 10, it was confirmed that most of the defective parts of e-PTFE were removed and the RMS roughness decreased to about 5 nm. Also, it was confirmed that copper (Cu) particles exist in a fine particle state in the copper thin film deposited on the e-PTFE substrate.

[0095] Fig. 11 shows SEM images at various magnifications of a Cu / e-PTFE thin film with 300 nm of Cu deposited by the method for manufacturing a flexible copper-clad laminate of a PTFE substrate according to the present invention.

[0096] In the SEM image of the Cu / e-PTFE thin film at low magnification, the state of the e-PTFE substrate can be confirmed. In the SEM image of the Cu / e-PTFE thin film at high magnification, the shape of the deposited copper can be observed, and it can be confirmed that copper (Cu) particles exist in a particle state as observed in Fig. 10.

[0097] When the method for manufacturing a flexible copper-clad laminate of a PTFE substrate according to the present invention uses a PTFE substrate 10 with a metal thin film 20 deposited by applying an atomic sputtering epitaxy (ASE) process for a semiconductor PCB, excellent high-temperature oxidation resistance characteristics can be realized. Therefore, there is an effect that the problem of circuit performance degradation due to heat generation of servers in ICT in the semiconductor industry can be solved.

[0098] In addition, in the method for manufacturing a flexible copper-clad laminate of a PTFE substrate according to the present invention, the copper oxide layer on the PTFE substrate 10 can be uniformly controlled by applying an Atomic Sputtering epitaxy (ASE) process. In the existing manufacturing method, since the polycrystalline metal thin film 20 is formed on the substrate, oxygen atoms are adsorbed at the grain boundaries inside the metal thin film 20, and the oxidation process becomes irregular. On the other hand, in the method for manufacturing a flexible copper-clad laminate using the PTFE substrate 10 according to the present invention, the metal thin film 20 deposited on the PTFE substrate 10 is a flat and dense thin film, and oxidation can proceed uniformly on the surface. Therefore, a material that can ensure the reliability of 5G communication quality can be realized. In the existing communication industry, there were problems of communication quality degradation and attenuation due to the formation of a copper oxide layer depending on the moisture content in the atmosphere (resonant absorption of rain, oxygen, and water molecules in the air). However, in the method for manufacturing a flexible copper-clad laminate of a PTFE substrate according to the present invention, the copper oxide layer can be controlled by the copper thin film on the PTFE substrate 10, so the reliability of communication quality can be ensured in a high-frequency environment.

[0099] Furthermore, in the method for manufacturing a flexible copper-clad laminate of a PTFE substrate according to the present invention, when a graphene thin film is grown on the copper thin film deposited on the PTFE substrate by an Atomic Sputtering epitaxy (ASE) process, it will have a very high thermal conductivity and can be used as a heat dissipation material for various electronic components such as OLEDs.

[0100] This specification has been described with reference to preferred embodiments of the present invention. However, those skilled in the art can variously modify and implement the present invention without departing from the spirit and scope of the present invention described in the claims set forth below. Therefore, any modification that basically includes the components of the claims of the present invention must be regarded as being included in the technical scope of the present invention.

Claims

1. A PTFE substrate preparation stage in which a substrate made of PTFE (Polytetrafluoroethylene) material is prepared in a chamber space of a vacuum chamber; a reaction gas injection step of evacuating a chamber space of the vacuum chamber for a sputtering process and then injecting a reaction gas therein; applying high frequency power to a target made of single crystal metal particles, the target being mounted on an upper portion of the inside of the vacuum chamber; and a metal thin film laminating step in which metal particles separated from the target are deposited on the PTFE substrate by the applied high frequency power to form a metal thin film.

2. 2. The method for manufacturing a flexible copper-clad laminate of a PTFE substrate according to claim 1, wherein the temperature of the chamber space of the vacuum chamber in which the PTFE substrate is prepared in the PTFE substrate preparation step is set to a range of 140°C to 200°C.

3. 2. The method of claim 1, wherein the gas injected into the chamber space of the vacuum chamber in the step of injecting a reaction gas includes argon (Ar).

4. 2. The method of claim 1, wherein the high frequency power is transmitted to the target mounted at an upper end inside the vacuum chamber through a power supply line made of a single crystal copper wire in the high frequency power application step.

5. 2. The method of claim 1, wherein the metal thin film lamination step comprises depositing the metal thin film on the PTFE substrate by an atomic sputtering epitaxy (ASE) process, which deposits metal particles on the PTFE substrate in atomic units.

6. 2. The method of claim 1, wherein the metal thin film is laminated on the PTFE substrate to a thickness of 100 to 300 nm in the metal thin film lamination step.

7. 2. The method of claim 1, wherein the metal particles in the metal thin film lamination step include copper (Cu).

8. 2. The method of claim 1, wherein the metal thin film lamination step absorbs or blocks vibrations transmitted to the vacuum chamber while metal particles separated from the target are deposited on the PTFE substrate.

9. 2. The method of claim 1, further comprising forming a pattern of a specific shape on the surface of the metal thin film laminated on the PTFE substrate.

10. 10. The method of claim 9, wherein the pattern formed in the forming of the metal thin film pattern has a hexagonal honeycomb shape with a line width of 5 μm to 14 μm.

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