Method for manufacturing a multilayer printed circuit board

Abstract

This invention relates to a method for manufacturing a multilayer printed circuit board, comprising: a step of preparing a first circuit board; a step of preparing a metal laminate; a step of stacking the first circuit board on both sides of a carrier film to form a first multilayer laminate; a step of stacking the metal laminate on both sides of the first multilayer laminate to form a second multilayer laminate; a step of hot-pressing the second multilayer laminate; a step of forming a second circuit pattern on the metal foil of the hot-pressed second multilayer laminate to form a third multilayer laminate; and a step of separating the carrier film and the first circuit board from the third multilayer laminate to obtain two multilayer printed circuit boards having the first circuit board and the second circuit board stacked on them, respectively, and adjusting the MFR of the dried film to be greater than the MFR of the first thermoplastic resin layer.

Description

Technical Field

[0001] This invention relates to a method for manufacturing a multilayer printed circuit board, and more specifically to a method for manufacturing a multilayer printed circuit board without a bonding sheet. Background Technology

[0002] Recently, with the increasing performance of electronic devices, there is a demand for extremely high operating speeds and high-frequency communication speeds. Furthermore, in order to improve multifunctionality and portability, there is a need for further development in terms of lightness, thinness, shortness, and miniaturization.

[0003] Therefore, printed circuit boards used in electronic devices require high-speed, low-loss signal transmission, high-density wiring, thinning, and lightweighting. Consequently, substrate materials also require low dielectric constants, low dielectric loss tangents, and thinning and lightweighting. For this reason, multilayer printed circuit boards using a build-up method have been utilized.

[0004] High-melting-point thermosetting resins, such as epoxy resin or polyimide resin, are widely used as the main insulating layer material for the aforementioned multilayer printed circuit boards. Insulating layers made from these thermosetting resins can impart good heat resistance and insulation properties to high-density multilayer printed circuit boards. However, in order to stack the circuit boards made of these thermosetting resins into multiple layers, adhesive sheets with lower melting or curing points than the main insulating layer are required, and further processes such as cutting, temporary bonding, and curing of each adhesive sheet are also necessary. Thus, the manufacturing cost increases due to the increased number of manufacturing steps and materials. Furthermore, since the overall thickness of the multilayer printed circuit board increases by a considerable amount compared to the thickness of the adhesive sheets used in the lamination process, the circuitry may be damaged during folding, or the elasticity of the adhesive sheet layers may cause springback characteristics to become prominent. Summary of the Invention

[0005] Technical issues

[0006] The present invention aims to provide a method for manufacturing a multilayer printed circuit board that exhibits excellent interlayer adhesion even without adhesive sheets, as well as low loss characteristics and excellent processability in the high-frequency region.

[0007] Technical solution

[0008] To address the aforementioned issues, the present invention provides a method for manufacturing a multilayer printed circuit board.

[0009] According to one example, a method for manufacturing a multilayer printed circuit board includes: preparing a first circuit board comprising a first thermoplastic resin layer and a first circuit pattern disposed on at least one side of the first thermoplastic resin layer; preparing a metal laminate comprising a metal foil and a dried film of a thermoplastic resin composition disposed on one side of the metal foil; stacking the first circuit board on both sides of a carrier film to form a first multilayer laminate; stacking the metal laminate on both sides of the first multilayer laminate to form a second multilayer laminate; hot-pressing the second multilayer laminate; forming a second circuit pattern on the metal foil of the hot-pressed second multilayer laminate to form a third multilayer laminate; and separating the carrier film and the first circuit board from the third multilayer laminate to obtain two multilayer printed circuit boards having the first circuit board and the second circuit board stacked on them, respectively, and adjusting the MFR of the dried film to be greater than the MFR of the first thermoplastic resin layer.

[0010] According to another example, before or after forming the second circuit pattern, the process may further include: processing a plurality of holes on the second multilayer laminate; and plating the plurality of holes to form through holes.

[0011] According to another example, it may further include: the step of preparing an nth metal laminate comprising an nth metal foil and an nth dry film of a thermoplastic resin composition disposed on one side of the nth metal foil; after the separation step of the multilayer printed circuit board, repeating the step of forming the first multilayer laminate to the separation step of the multilayer printed circuit board one or more times; and using the separated multilayer printed circuit board instead of the first circuit board to form the first multilayer laminate; using the nth metal laminate instead of the metal laminate to form the second multilayer laminate; and it may be adjusted such that as the flow rate (MFR) of each dry film gradually increases (n is an integer greater than or equal to 3) from the first thermoplastic resin layer toward the nth dry film.

[0012] The effects of the invention

[0013] Unlike conventional methods, the manufacturing method of the multilayer printed circuit board of the present invention does not involve cutting or temporarily bonding adhesive sheets, thus simplifying the manufacturing process. It can also be applied to roll-to-roll processes using a belt press to manufacture roll-shaped multilayer printed circuit boards. In this method, the manufactured multilayer printed circuit board is built up by directly bonding the circuit board with a single material without adhesive sheets, thereby achieving environmental reliability and low dielectric loss in high-frequency regions.

[0014] Furthermore, the multilayer printed circuit board manufactured by this invention, through the thinning of the product, enables the realization of 3D-shaped circuits formed by bending and folding, thereby improving processability.

[0015] Meanwhile, the multilayer printed circuit board manufactured by this invention has excellent low-loss characteristics in the high-frequency region because each thermoplastic resin layer contains fluorine components. Attached Figure Description

[0016] Figure 1 This is a schematic cross-sectional view illustrating an example of the process of manufacturing a multilayer printed circuit board according to the present invention.

[0017] Figure 2 This is a schematic cross-sectional view of a multilayer printed circuit board manufactured according to an example of the present invention.

[0018] Figure 3 It is Figure 2 An enlarged sectional view of part A.

[0019] Figure 4 This is a schematic cross-sectional view of a multilayer printed circuit board manufactured according to another example of the present invention.

[0020] <Figure Labels>

[0021] 110: First circuit board; 111: First thermoplastic resin layer; 112: First circuit pattern; 113: Fiber-containing substrate; 120a: Metal laminate; 121a: First dry film; 122a: Metal foil; 10: Carrier film; 20: Protective metal foil; H: Hole; Via: Through hole; 100A, 100B: Multilayer printed circuit board; 120: Second circuit board; 121: Second thermoplastic resin layer; 122: Second circuit pattern; Via: Through hole; 130: Third circuit board; 131: Third thermoplastic resin layer; 132: Third circuit pattern. Detailed Implementation

[0022] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. These embodiments are provided to illustrate the invention more completely to those skilled in the art. The following embodiments can be modified in many different ways, and the scope of the invention is not limited to the following embodiments. Throughout this specification, the same reference numerals refer to the same structures.

[0023] Unless otherwise defined, all terms used in this specification (including technical and scientific terms) may be used in the sense that would be commonly understood by one of ordinary skill in the art. Furthermore, unless explicitly defined, terms as defined in commonly used dictionaries should not be interpreted ideally or excessively.

[0024] Furthermore, the sizes and thicknesses of the components shown in the figures are arbitrary for ease of explanation, and the present invention is not necessarily limited to the illustrations. To clearly represent multiple layers and regions in the figures, the thicknesses are shown enlarged. Additionally, for ease of explanation, the thicknesses of some layers and regions are exaggerated in the figures.

[0025] Furthermore, throughout the specification, when a part is referred to as "containing" a certain constituent element, unless otherwise stated to the contrary, it means that other constituent elements are not excluded, but may be included.

[0026] Furthermore, throughout the instruction manual, "above" or "above" includes not only the case of being above or below the object part, but also the case of having other parts in between, and does not necessarily mean being above with respect to the direction of gravity.

[0027] In addition, in the application description, terms such as "first" and "second" do not indicate any arbitrary order or importance, but are used to distinguish the constituent elements from each other.

[0028] The manufacturing method of the multilayer printed circuit board of the present invention manufactures the multilayer printed circuit board without using a bonding sheet, unlike conventional methods which involve cutting and processing the bonding sheet. Furthermore, the present invention can simultaneously manufacture two multilayer printed circuit boards using a carrier film. Therefore, the present invention simplifies the manufacturing process, thereby reducing manufacturing costs and shortening process time to increase productivity. In addition, the present invention can easily manufacture roll-to-roll multilayer printed circuit boards using roll-to-roll processes, particularly using a belt press.

[0029] Figure 1 This is a schematic cross-sectional view illustrating an example of the process of manufacturing a multilayer printed circuit board according to the present invention.

[0030] According to one example, such as Figure 1As shown, a method for manufacturing a multilayer printed circuit board according to an example of the present invention includes: (S100) preparing a first circuit board 110 comprising a first thermoplastic resin layer 111 and a first circuit pattern 112 disposed on at least one side of the first thermoplastic resin layer 111; (S200) preparing a metal laminate 120a comprising a metal foil 122a and a dried film 121a of a thermoplastic resin composition disposed on one side of the metal foil 122a; (S300) stacking the first circuit board 110 on both sides of a carrier film 10 to form a first multilayer laminate; (S400) stacking the metal laminate 120a on both sides of the first multilayer laminate to form a second multilayer laminate; (S500) hot-pressing the second multilayer laminate. The steps include: (S600) forming a second circuit pattern on the metal foil 122a of the second multilayer laminate after hot pressing to form a third multilayer laminate; and (S700) separating the carrier film 10 and the first circuit board 110 from the third multilayer laminate to obtain two multilayer printed circuit boards 100A with the first circuit board 110 and the second circuit board 120 stacked on it, and adjusting the MFR of the dried film 121a to be greater than the MFR of the first thermoplastic resin layer 111.

[0031] Optionally, the method for manufacturing a multilayer printed circuit board according to an example of the present invention may further include, before or after forming the second circuit pattern, the step of (S800) processing a plurality of holes on the second multilayer laminate; and (S900) plating the plurality of holes to form through holes.

[0032] Furthermore, a method for manufacturing a multilayer printed circuit board according to an example of the present invention may further include: preparing an nth metal laminate comprising an nth metal foil and an nth dry film of an nth thermoplastic resin composition disposed on one side of the nth metal foil; after the separation step of the multilayer printed circuit board, repeating the steps from forming the first multilayer laminate [“step S300”] to the separation step of the multilayer printed circuit board [“step S700”] once or more; using the separated multilayer printed circuit board 100A to replace the first circuit board 110 to form a first multilayer laminate; using the (n-1)th metal laminate (not shown) to replace the metal laminate 120a to form a second multilayer laminate; and adjusting such that the MFR of each dry film gradually increases as it moves from the first thermoplastic resin layer toward the nth dry film, wherein n can be an integer greater than or equal to 3.

[0033] However, the manufacturing process is not limited to the steps described above, nor is it necessary to perform each step sequentially. Instead, the steps of each process can be modified or selectively combined according to the design specifications. In particular, there is no temporal order between steps S100 and S200.

[0034] The following is for reference. Figure 1 The steps of a method for manufacturing a multilayer printed circuit board using a roll-to-roll apparatus according to an example of the present invention will be described.

[0035] Step S100: Preparation steps for the first circuit board

[0036] A first circuit board 110 is prepared, comprising a first thermoplastic resin layer 111 and a first circuit pattern 112 disposed on at least one side of the first thermoplastic resin layer 111.

[0037] The first circuit board 110 used in this invention can be panel-type or roll-type. As an example, the first circuit board 110 is roll-type, specifically a roll-type double-sided circuit board, and more specifically a roll-type double-sided flexible circuit board.

[0038] According to one example, such as Figure 1 As shown, the first circuit board 110 includes a first thermoplastic resin layer 111 and first circuit patterns 112 respectively disposed on both sides of the first thermoplastic resin layer 111. Optionally, the first circuit board 110 may further include a fiber-containing substrate 113 embedded in the first thermoplastic resin layer 111.

[0039] The following describes the various configurations of the first circuit board 110.

[0040] (1) First thermoplastic resin layer

[0041] The first thermoplastic resin layer 111 is an insulating layer that directly bonds to the dry film 121a to add layers to the circuit board while protecting the first circuit pattern 112. To ensure the dimensional stability of the first circuit pattern 112 when the second circuit board 120 is laminated onto the first circuit board 110, it is preferable that the first thermoplastic resin layer 111 is a fully cured insulating layer.

[0042] As previously stated, the melt flow rate (MFR) of the first thermoplastic resin layer 111 is less than the MFR of the second thermoplastic resin layer 121. According to one example, the MFR of the dried film 121a can be 10 to 100 times greater than the MFR of the first thermoplastic resin layer 121. The MFR of the first thermoplastic resin layer 111 at a temperature of 372°C and a load of 5 kg can be approximately 0 to 1 g / 10 min, specifically in the range of approximately 0.01 to 1 g / 10 min. The MFR of the dried film 121a at a temperature of 372°C and a load of 5 kg can be greater than 1.5 g / 10 min and less than 5 g / 10 min. Here, the MFR (Melt Flow Rate) of the resin layers and the dried film is the total amount of resin extruded within 10 minutes, measured according to ISO 12086-2 test method at 372°C and 5 kg.

[0043] The relative permittivity (Dk) of the first thermoplastic resin layer 111 can be about 2 to 7 at 25°C and 10 GHz, and the dielectric loss tangent (Df) can be 0.0001 to 0.002.

[0044] The first thermoplastic resin layer 111 may contain thermoplastic components known in the art. As an example, the first thermoplastic resin layer 111 may be formed from a first thermoplastic resin composition (C1) comprising a first fluororesin filler, a first inorganic filler, and a first adhesive resin. Optionally, the first thermoplastic resin composition (C1) may further contain a first organic solvent.

[0045] The composition of the first thermoplastic resin composition (C1) will be described below.

[0046] 1) First fluororesin filler

[0047] In the first thermoplastic resin composition (C1) of the present invention, the first fluororesin filler is a fluorine-containing (F) fluorine-based resin particle, which is a particulate organic filler such as powder that is solid at room temperature (about 20±5°C). When the first thermoplastic resin composition (C1) is dried, this first fluororesin filler, while maintaining its particle morphology, is bonded together with the first inorganic filler using a first adhesive resin. Subsequently, it is melted under high temperature and pressure and, together with the first adhesive resin, is included as a polymer matrix component in the first thermoplastic resin layer 111. Therefore, the first fluororesin filler not only achieves low dielectric constant and low dielectric loss characteristics in the first thermoplastic resin layer, but also improves heat resistance and adhesion to fiber-containing substrates or metal foils.

[0048] As the first fluororesin filler that can be used in this invention, there is no particular limitation as long as it is formed from particles of a fluorine-containing resin in the art. Non-limiting examples of the first fluororesin filler include polytetrafluoroethylene (PTFE), perfluoroalkoxyalkane (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), polychlorotrifluoroethylene (PCTFE), ethylene-tetrafluoroethylene copolymer (ETFE), tetrafluoroethylene-chlorotrifluoroethylene copolymer (TFE / CTFE), ethylene-chlorotrifluoroethylene copolymer (ECTFE), and polychlorotrifluoroethylene (PCTFE), which can be used alone or in combination. As an example, the first fluororesin filler may contain two or more selected from the group consisting of PFA, PTFE, and FEP.

[0049] The melt flow rate (MFR) of such a first fluoropolymer filler can vary depending on the type or molecular weight of the filler, or the mixing ratio of two or more fillers. For example, the MFR of PTFE is 0~0.1 g / 10 min (specifically about 0.01~1 g / 10 min), the MFR of PFA is about 0.1~20 g / 10 min, and the MFR of FEP can be about 1~40 g / min. Thus, the MFR of the first fluoropolymer filler can be in the range of about 0.01 to 40 g / 10 min at a temperature of 372°C and a load of 5 kg. In this case, the MFR of the first fluoropolymer filler is preferably less than the MFR of the second fluoropolymer filler in the second thermoplastic resin composition. As a result, the dimensional stability and flow stability of the first thermoplastic resin layer 111 at the same temperature are superior to those of the dry film 121a, thereby improving the dimensional stability of the first circuit pattern 112. Here, the MFR (Melt Flow Rate) of the first fluoropolymer is the total amount of resin extruded within 10 minutes, measured according to ISO 12086-2 at 372°C and 5 kg. When the first fluoropolymer is a mixture of two or more, the MFR of the mixture is determined.

[0050] In this invention, the first fluororesin filler comprises two or more fluororesin fillers with different MFRs. By adjusting their mixing ratio, the MFR of the first thermoplastic resin layer 111 can be adjusted to approximately 0-0.1 g / 10 min, specifically within the range of approximately 0.01-1 g / 10 min. For example, the first fluororesin filler may include: a first A fluororesin filler having an MFR of approximately 0.01 to 10 g / 10 min at a temperature of 372°C and a load of 5 kg; and a first B fluororesin filler having an MFR of approximately 0.1 to 40 g / 10 min. In this case, the content of the first A fluororesin filler can be greater than the content of the first B fluororesin filler.

[0051] As an example, the first fluoropolymer filler may include: (a) PTFE; and (b) one or more selected from the group consisting of PFA and FEP, wherein the content of PTFE may be greater than the content of PFA and / or FEP. The ratio of PTFE to PFA and / or FEP (PTFE:PFA and / or FEP) may be a weight ratio of 2:1 to 10:1. Furthermore, when PTFE is used together with PFA and FEP as the first fluoropolymer filler, the content of PFA may be adjusted to be greater than the content of FEP so that the MFR of the first thermoplastic resin layer 111 is less than the MFR of the second thermoplastic resin layer 121. Here, PFA and / or FEP means PFA, or FEP, or a mixture of PFA and FEP.

[0052] As another example, the first fluoropolymer filler may comprise: (a) PTFE; and (b) PFA, wherein the content of PTFE may be greater than the content of PFA. The ratio of PTFE to PFA used (PTFE:PFA) may be a weight ratio of 2:1 to 10:1.

[0053] As another example, the first fluororesin filler may contain fluororesin fillers with a smaller MFR, such as PTFE. In this case, the second fluororesin may contain fluororesin fillers with an MFR greater than PTFE, such as PFA, PTFE, or both. Furthermore, the second fluororesin may further contain PTFE, in which case the PTFE content in the second fluororesin is less than the PTFE content in the first fluororesin filler.

[0054] In addition, the average particle size D of the first fluororesin filler 50 The particle size can be in the range of approximately 5 to 30 μm. When the first fluororesin filler has the aforementioned average particle size, the first fluororesin filler is not only uniformly dispersed in the first thermoplastic resin composition (C1) without agglomeration, but the processability of the first thermoplastic resin composition (C1) after coating can also be improved. In this invention, as the first fluororesin filler, a single fluororesin filler with the same average particle size can be used, or two or more fluororesin fillers with different average particle sizes can be mixed and used. Here, the average particle size D of the first fluororesin filler... 50 It can be determined according to the ASTM D4464-10 test method.

[0055] According to one example, the first fluoropolymer filler may include: an average particle size D 50 The first type of fluororesin filler is 20 to 30 μm; and the average particle size D 50 The 1B fluoropolymer is 5 to 10 μm thick.

[0056] Furthermore, the first fluoropolymer filler can exhibit a relative permittivity (Dk) of approximately 2.0 to 2.1 and a dielectric loss tangent (Df) of 0.0001 to 0.002 at 25°C and 10 GHz. Thus, due to the low dielectric properties of the first fluoropolymer filler, low dielectric constant and low dielectric loss characteristics of the first thermoplastic resin layer 111 can be achieved. Here, the relative permittivity (Dk) and dielectric loss tangent (Df) of the first fluoropolymer filler were measured at 25°C and 10 GHz using the split postdielectric resonator (SPDR) method (IEC 61189-2-721 test method).

[0057] Furthermore, the shape of the first fluororesin filler is not particularly limited; for example, it can be spherical, flake-like, dendrite-like, conical, pyramidal, or amorphous. These can be used alone or in combination. According to one example, the first fluororesin filler can be spherical. In this case, the surface area of ​​the first fluororesin filler is minimized, thus improving the processing characteristics of the first thermoplastic resin composition and imparting isotropic properties to the first thermoplastic resin layer.

[0058] In the first thermoplastic resin composition (C1) of the present invention, the content of the first fluororesin filler can be in the range of about 50 to 80% by weight, based on the total amount of the resin composition. By adjusting the content of the first fluororesin filler within the aforementioned range, the resin composition can form a resin layer with a low dielectric constant.

[0059] As an example, when the first fluororesin filler contains PTFE and PFA in a weight ratio of 10:1, and the content of the first fluororesin filler is adjusted to about 50% by weight, the content of the first inorganic filler is adjusted to about 45% by weight, and the content of the first adhesive resin is adjusted to about 5% by weight, the MFR of the first thermoplastic resin layer can be 0 g / 10 min.

[0060] As another example, when the first fluoropolymer filler contains PTFE and PFA in a weight ratio of 2:1, and the content of the first fluoropolymer filler is adjusted to about 80% by weight, the content of the first inorganic filler is adjusted to about 17% by weight, and the content of the first adhesive resin is adjusted to about 3% by weight, the MFR of the first thermoplastic resin layer can be about 1 g / 10 min.

[0061] 2) First inorganic packing

[0062] In the first thermoplastic resin composition (C1) of the present invention, the first inorganic filler reduces the difference in coefficient of thermal expansion (CTE) between the first thermoplastic resin layer 111 and other layers [e.g., the first circuit pattern 112, the fiber-containing substrate 113], thereby improving the warpage characteristics, low expansion, mechanical strength (toughness), and low stress of the first circuit board 110. Furthermore, the dielectric properties of the first thermoplastic resin layer 111 can be adjusted according to the composition and / or content of the first inorganic filler.

[0063] Non-limiting examples of first inorganic fillers that can be used in this invention include: silica such as natural silica, fused silica, amorphous silica, crystalline silica, etc.; boehmite, alumina, magnesium silicate monohydrate (Talc), glass (e.g., spherical glass), calcium carbonate, magnesium carbonate, magnesium oxide, clay, calcium silicate, titanium dioxide, antimony oxide, glass fiber, aluminum borate, barium titanate, strontium titanate, calcium titanate, magnesium titanate, bismuth titanate, titanium dioxide (e.g., TiO2), barium zirconate, calcium zirconate, boron nitride, silicon nitride, talc, mica, etc. Such first inorganic fillers can be used alone or in combination of two or more. Silica, alumina, and titanium dioxide have low dielectric constants, thus reducing the difference in thermal expansion coefficients between the resin layer and the metal foil, while simultaneously reducing the dielectric constant and dielectric loss tangent of the resin layer.

[0064] According to one example, the first inorganic filler may comprise one or more selected from the group consisting of silica (e.g., SiO2), alumina (e.g., Al2O3), and titanium dioxide (e.g., TiO2). According to another example, the first inorganic filler may be: titanium dioxide (e.g., TiO2); and silica (e.g., SiO2). In this case, the content of titanium dioxide may be greater than that of silica. For example, based on the total amount of the resin composition, the content of titanium dioxide may be about 20-30% by weight.

[0065] The size (e.g., average particle size, maximum particle size), shape, and content of such first inorganic fillers are important parameters affecting the properties of the first thermoplastic resin layer.

[0066] Specifically, the average particle size D of the first inorganic filler 50 The particle size can be in the range of approximately 0.1 to 30 μm. This is advantageous in terms of the dispersibility of the first inorganic filler. In this case, the first inorganic filler can contain two or more inorganic fillers with different maximum particle sizes.

[0067] According to one example, the first inorganic filler may include: an average particle size D 50 The first type of inorganic filler is approximately 0.1 to 10 μm in size; and the average particle size D is... 50 The first inorganic filler is larger than approximately 10 μm and smaller than 30 μm. In this case, the first inorganic filler may contain two or more inorganic fillers with different compositions, and the first inorganic filler may also contain two or more inorganic fillers with different compositions. For example, the first inorganic filler may include: an average particle size D... 50 The first type of inorganic filler is 0.1 to 10 μm; and the average particle size D 50 The first inorganic filler, denoted as 1B, has a particle size greater than approximately 10 μm and less than 30 μm. The first inorganic filler may contain silica and titanium dioxide. Here, the average particle size D of the first inorganic filler is... 50 It can be determined according to ASTM D4464-10.

[0068] Furthermore, the shape of the first inorganic filler is not particularly limited, and it can be spherical, plate-like, dendrite-like, conical, pyramidal, amorphous, etc.

[0069] Furthermore, the first inorganic filler may be surface-treated with a surface treatment agent. There are no particular limitations on the surface treatment agent, as long as it is commonly known in the art, such as a silane coupling agent. In this case, based on 100 parts by weight of the first inorganic filler, the content of the silane coupling agent may be approximately 0.1 to 20 parts by weight, specifically approximately 0.1 to 10 parts by weight.

[0070] The silane coupling agents that can be used in this invention are not particularly limited as long as they are commonly known in the art, such as vinyl-based, epoxy-based, methacryloxy-based, amino-based, mercapto / sulfide-based, and urea-based silane coupling agents. They can be used alone or in combination of two or more. Such silane coupling agents can improve the adhesion between the first inorganic filler and other components when the resin composition is cured.

[0071] The aforementioned silane coupling agent not only performs surface treatment on the first inorganic filler, but can also be further added as a component of the first thermoplastic resin composition (C1). In this case, the dispersibility of the first inorganic filler is improved by the silane coupling agent, thereby enhancing the low dielectric properties of the first thermoplastic resin layer.

[0072] Based on the total amount of the resin composition, the content of such silane coupling agent can be from about 0.0001 to 10% by weight, specifically from about 0.01 to 5% by weight, and more specifically from about 0.1 to 3% by weight.

[0073] In the resin composition of the present invention, the content of the first inorganic filler can be in the range of about 20% to 50% by weight, specifically about 30% to 45% by weight, based on the total amount of the resin composition. When the content of the first inorganic filler is less than about 20% by weight, the mechanical strength improvement effect may not be significant and it may be difficult to apply it to the process; while when the content of the first inorganic filler is greater than about 50% by weight, the moldability of the resin composition may decrease.

[0074] 3) First adhesive resin

[0075] In the first thermoplastic resin composition (C1) of the present invention, the first adhesive resin is an adhesive resin with excellent high-temperature heat resistance, which can bond the first fluororesin filler and the first inorganic filler during the formation of the first thermoplastic resin layer. Furthermore, the first adhesive resin has excellent adhesion (bonding strength) to the metal foil, thereby improving the bonding characteristics between the dried product of the first thermoplastic resin composition (C1) and the metal foil.

[0076] The thermal decomposition temperature (Td) of such a first adhesive resin can be above approximately 400°C, specifically in the range of approximately 400 to 450°C.

[0077] Furthermore, the dielectric loss tangent (Df) of the first adhesive resin at 10 GHz can be in the range of approximately 0.0001 to 0.002, and the dielectric constant (Dk) at 10 Hz can be in the range of approximately 2.0 to 3.0. In this case, the low dielectric properties of the first thermoplastic resin layer 111 can be improved. Here, the relative dielectric constant (Dk) and dielectric loss tangent (Df) of the first adhesive resin are measured at 25°C and 10 GHz according to the split post dielectric resonator (SPDR) method (IEC 61189-2-721 test method).

[0078] Furthermore, the viscosity (at approximately 25°C) of the solution in which 5 wt% of the first adhesive resin is dissolved in an organic solvent (e.g., toluene) can be approximately 50 to 100 cPs. In this case, the viscosity of the first thermoplastic resin composition (C1) of the present invention is adjusted to a range of approximately 150 to 500 cPs, thereby improving processability when manufacturing a rolled first circuit board. Here, the viscosities of the first adhesive resin and the resin composition are measured using viscometry methods known in the art, such as the Blook field method (rotation speed: approximately 20 rpm).

[0079] According to one example, the first adhesive resin may be a fluoroelastomer.

[0080] The fluorinated elastomer is a thermoplastic elastomer containing more than one fluorine (F) element in at least one repeating unit, unlike the first fluorinated resin filler, and is soluble in organic solvents. Such fluorinated elastomers have thermal decomposition temperatures (Td) exceeding 400°C, and low dielectric loss tangent (Df) and relative permittivity (Dk).

[0081] The fluoroelastomers that can be used in this invention are fluororubbers (FKM), specifically copolymers containing two or more of vinylidene fluoride (VDF), hexafluoropropylene (HFP), and tetrafluoroethylene (TFE). Depending on the number of monomers, they can be binary or ternary copolymers, such as VDF-HFP copolymers, VDF-HFP-TFE copolymers, etc., but are not limited to these. They can be used alone or in combination of two or more.

[0082] The fluorine (F) content in such fluorinated elastomers is not particularly limited. When the content of the fluorinated elastomer per molecule is in the range of about 65 to 80% by weight, it can impart excellent low dielectric properties and low dielectric loss properties to the first thermoplastic resin layer 111.

[0083] In the first thermoplastic resin composition (C1), based on the total amount (100% by weight) of the first thermoplastic resin composition (excluding organic solvents and additives), the content of the first adhesive resin may be in the range of about 1 to 10% by weight, specifically in the range of about 1 to 7% by weight, and more specifically in the range of about 1 to 5% by weight. When the content of the first adhesive resin is less than about 1% by weight, the effect of the adhesive filler may decrease; and when the content of the first adhesive resin is greater than 10% by weight, the adhesion to the fiber-containing substrate 113 and the adhesion to the metal foil (e.g., copper foil) decreases, and the metal foil (circuit pattern) may peel off when manufacturing and using the rolled first circuit board.

[0084] 4) First organic solvent

[0085] The first thermoplastic resin composition (C1) of the present invention may further comprise a first organic solvent.

[0086] The first organic solvent that can be used in this invention is not particularly limited as long as it can dissolve the first adhesive resin. Examples of such first organic solvents include: aromatic compounds such as toluene, xylene, and ethylbenzene; alcohol compounds such as methanol, ethanol, butanol, and isobutanol; ketone compounds such as acetone, methyl isobutyl ketone, methyl pentyl ketone, cyclohexanone, isophorone, and N-methylpyrrolidone; and ester compounds such as ethyl acetate, butyl acetate, and methyl cellosolve acetate, but are not limited thereto. They can be used alone or in combination.

[0087] The content of the first organic solvent can be used in accordance with the content known in the art, and can be adjusted to make the total amount of the first thermoplastic resin composition (C1) 100% by weight. As an example, based on 100 parts by weight of the first thermoplastic resin composition (C1) (wherein excluding the first organic solvent and the first additive), it can be in the range of about 40 to 70 parts by weight, specifically in the range of about 45 to 65 parts by weight.

[0088] 5) First additive

[0089] On the other hand, the first thermoplastic resin composition (C1) of the present invention may further include, as needed, first additives known in the art, such as flame retardants, other thermosetting or thermoplastic resins, ultraviolet absorbers, antioxidants, polymerization initiators, dyes, pigments, dispersants, thickeners, leveling agents, colorants, etc., without impairing the physical properties of the composition.

[0090] The content of the first additive can be used in accordance with the content known in the art, for example, based on the total amount of the first thermoplastic resin composition (C1), it can be about 0.0001 to 10 by weight.

[0091] The viscosity of the first thermoplastic resin composition (C1) of the present invention can be adjusted according to the type or content of the first fluororesin filler, the first inorganic filler, the first adhesive resin, and the first organic solvent in the composition, for example, it can be about 200 to 1000 cPs. According to one example, when the first thermoplastic resin composition (C1) has the aforementioned viscosity, the first thermoplastic resin layer 111 can be directly formed on the metal foil by directly coating the first thermoplastic resin composition (C1) onto the metal foil using a roll-to-roll coating method and then drying it.

[0092] (b) First circuit diagram

[0093] In the first circuit board 110 of the present invention, a first circuit pattern 112 is disposed on both sides of the aforementioned first thermoplastic resin layer 111 and is patterned into a predetermined shape having a predetermined width and thickness. Such a first circuit pattern 112 can perform various functions depending on the design of the corresponding layer, such as a power supply line, a grounding line, or a grounding electrode. Thus, the first circuit patterns 112 disposed on both sides of the first thermoplastic resin layer 111 can be partially electrically connected to each other, or electrically connected to circuit patterns in other substrates [e.g., a second circuit pattern 122, etc.] through vias.

[0094] The material used to form the first circuit pattern 112 is not particularly limited as long as it is a conductive material commonly used in the art, specifically a conductive metal. Non-limiting examples of the aforementioned conductive materials include chromium (Cr), nickel (Ni), zinc (Zn), molybdenum (Mo), tungsten (W), cobalt (Co), lead (Pb), silver (Ag), tantalum (Ta), copper (Cu), aluminum (Al), manganese (Mn), iron (Fe), titanium (Ti), tin (Sn), steel, zinc (Zn), vanadium (V), palladium (Pd), etc., which can be used alone, or in combination of two or more, or in alloy form. According to one example, the material of the first circuit pattern 112 may be copper (Cu).

[0095] (c) Fiber-containing substrate

[0096] The first circuit board 110 of the present invention may further include a fiber-containing substrate 113.

[0097] As an example, such as Figure 3 As shown, it may further include a fiber-containing substrate 113 embedded in the first thermoplastic resin layer 111.

[0098] As another example, although not illustrated, it may further include a fiber-containing substrate 113 between the first thermoplastic resin layer 111.

[0099] The fiber-containing substrate 113 is the portion that supports the first circuit board 110. Because it contains fibers, the low dielectric constant and low loss characteristics of the first circuit board 110 can be improved. In addition, the fiber-containing substrate 113 is closely bonded to the dried product of the first thermoplastic resin sinter during the manufacture of the first circuit board, thereby exhibiting excellent flexibility, heat resistance and adhesion.

[0100] As an example, the fiber-containing substrate 113 can be a fiber aggregate.

[0101] As another example, the fiber-containing substrate 113 may be a prepreg comprising a fiber assembly and a semi-cured resin impregnated in the fiber assembly with a thermal decomposition temperature of 450°C or higher. Here, the semi-cured resin is a resin in a semi-cured B-stage state obtained by impregnating a high heat-resistant resin composition with a thermal decomposition temperature of 450°C or higher in the fiber assembly and then heating it.

[0102] The fiber assembly can be multiple fibers, or a fiber-containing substrate composed of fibers, such as yarn, woven fabric, non-woven fabric, knitting, braid, etc.

[0103] Non-limiting examples of the aforementioned fibers include: plant fibers such as cotton and linen; animal fibers such as wool and silk; regenerated fibers such as rayon; synthetic fibers such as polyester, acrylic, nylon, and polyurethane; inorganic fibers such as glass fiber and carbon fiber; and metal fibers, which can be used alone or in combination of two or more. In the case of inorganic fibers such as glass fiber and carbon fiber, due to their low moisture content, no pores are formed in the fiber-containing substrate 113 during subsequent hot pressing, and their thermal stability is also excellent.

[0104] Examples of the aforementioned fiber assemblies include various glass fibers (e.g., E-glass, D-glass, S-glass, NE-glass, T-glass, and Q-glass), cellophane, glass roving, glass yarn, woven fabric, glass chopped strands mat, glass roving cloth, and glass surfacing mat. However, these are not the only examples.

[0105] The semi-cured resin that can be used in this invention is a cured product of a high heat-resistant resin composition with a thermal decomposition temperature of 400°C or higher (stage B). The high heat-resistant resin composition that can be used in this invention is not particularly limited as long as it is commonly used in the art for prepregs and has a thermal decomposition temperature of 400°C or higher.

[0106] According to one example, the high heat-resistant resin composition may comprise one or more high heat-resistant resins selected from the group consisting of epoxy resins and fluororesins, and optionally may also include a curing agent.

[0107] In the above-mentioned high heat-resistant resin composition, epoxy resin is a thermosetting resin. After curing, it forms a three-dimensional network structure, which can improve the adhesion between the prepreg 113 and the first thermoplastic resin layer 111. Furthermore, it exhibits excellent heat resistance, water resistance, and moisture resistance, thereby improving the heat resistance reliability of the first circuit board. In addition, epoxy resin not only possesses excellent mechanical strength, electrical insulation, chemical resistance, dimensional stability, and moldability, but also exhibits excellent compatibility with other resins.

[0108] The epoxy resin used in this invention is a polymer containing at least one epoxy group within its molecule, and is preferably an epoxy resin that does not contain halogen atoms such as bromine within its molecule. Furthermore, the epoxy resin molecule may contain not only organosilicon, urethane, polyimide, polyamide, etc., but also phosphorus atoms, sulfur atoms, nitrogen atoms, etc.

[0109] As non-limiting examples of such epoxy resins, there are glycidyl ether epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, or their hydrides; glycidyl ether epoxy resins such as phenolic varnish type epoxy resin and cresolic varnish type epoxy resin; glycidyl ester epoxy resins such as glycidyl hexahydrophthalic acid and glycidyl dimer acid; glycidyl amine epoxy resins such as triglycidyl isocyanurate and tetraglycidyl diaminodiphenylmethane; and linear aliphatic epoxy resins such as epoxidized polybutadiene and epoxidized soybean oil. These can be used alone or in combination of two or more.

[0110] In the above-mentioned high heat-resistant resin composition, the fluoropolymer is a thermoplastic resin with excellent chemical stability and high-temperature thermal stability. It is a heat-resistant resin with a melting point (Tm) of about 260°C or higher, and is preferably in a liquid state. Examples of such fluoropolymers include polytetrafluoroethylene (PTFE), perfluoroalkoxyalkane (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), polychlorotrifluoroethylene (PCTFE), ethylene-tetrafluoroethylene copolymer (ETFE), ethylene-chlorotrifluoroethylene copolymer (ECTFE), tetrafluoroethylene-chlorotrifluoroethylene copolymer (TFE / CTFE), polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), and tetrafluoroethylene-perfluoroalkyl vinyl ether-hexafluoropropylene copolymer, but are not limited to these.

[0111] In the above-mentioned high heat-resistant resin composition, the curing agent, as the component that cures the epoxy resin, is not particularly limited as long as it is a substance commonly used in the art to cure epoxy resin, such as anhydride-based curing agents, amine-based curing agents, phenol-based curing agents, etc.

[0112] Specifically, examples of curing agents include: tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, hexahydrophthalic anhydride, trialkyltetrahydrophthalic anhydride, methylcyclohexene dicarboxylic anhydride, phthalic anhydride, maleic anhydride, pyromellitic anhydride, and other anhydride-based curing agents; m-phenylenediamine, diaminodiphenylmethane, diaminodiphenyl sulfone, and other aromatic amine-based curing agents; diethylenetriamine, triethylenetetramine, and other aliphatic amine-based curing agents; and phenolic aromatics. Phenolic curing agents include, but are not limited to, basic phenolic resins, phenolic varnish-type phenolic resins, phenol-aryl (Xylok) type phenolic resins, cresol phenolic varnish-type phenolic resins, naphthol type phenolic resins, terpene type phenolic resins, multifunctional phenolic resins, dicyclopentadiene-based phenolic resins, naphthol type phenolic resins, and phenolic varnish-type phenolic resins synthesized from bisphenol A and methyl phenolic resins; latent curing agents such as dicyandiamide; and others. These can be used alone or in combination of two or more.

[0113] There is no particular limitation on the content of such curing agent. For example, based on 100 parts by weight of high heat-resistant resin (e.g., epoxy resin), it can be about 1 to 10 parts by weight, specifically about 1 to 6 parts by weight.

[0114] The thickness of the aforementioned fiber-containing substrate 113 is not particularly limited, for example, it can be about 10 to 200 μm. However, when the thickness of the fiber-containing substrate 113 is in the range of about 30% to 70% based on the thickness of the flexible metal laminate, the thermal and mechanical properties of the first circuit board can be further improved.

[0115] The aforementioned first circuit board 110 can be manufactured by a variety of methods known in the art.

[0116] For example, a circuit can be manufactured by continuously feeding a roll of metal laminate using a roll-to-roll device, creating holes in the metal laminate for through-hole plating, and then etching the coated metal foil (e.g., copper foil) to form a circuit.

[0117] The metal laminate (hereinafter referred to as the "first metal laminate") includes a first thermoplastic resin layer and metal foils respectively disposed on both sides of the first thermoplastic resin layer, and may be in roll form.

[0118] Such a rolled first metal laminate can be manufactured by a variety of methods known in the art.

[0119] As an example, the manufacture of a roll of first metal laminate may include: coating one side of a continuously supplied first metal foil with a first A thermoplastic resin composition and drying it to continuously form a roll of first unit component comprising the first A metal foil and the first A thermoplastic resin composition (hereinafter referred to as "first A dry film"); coating one side of a continuously supplied first B metal foil with a first B thermoplastic resin composition and drying it to continuously form a roll of second unit component comprising the first B metal foil and the first B thermoplastic resin composition (hereinafter referred to as "first B dry film"); and stacking the second unit component on the first unit component in such a way that the dry films of each unit component are in contact with each other, followed by heating and pressurizing. Optionally, a fiber-containing substrate may be disposed between the aforementioned dry films.

[0120] Each of the aforementioned first and second unit components is a roll-shaped component formed on one side of each metal foil after the resin composition has been directly coated (applied) onto one side and then dried, resulting in a dried film formed from the solvent removed from the coated resin composition. Such first and second unit components can be manufactured by directly coating each resin composition onto each metal foil and then drying it without a film-forming process or a high-temperature sintering process. In this case, due to the excellent adhesion between the dried film and the metal foil, the durability of the metal laminate can be improved.

[0121] The aforementioned thermoplastic resin composition 1A comprises fluoropolymer filler 1A, inorganic filler 1A, and adhesive resin 1A, and may optionally comprise organic solvent 1A.

[0122] The above-mentioned thermoplastic resin composition 1B may be the same as or different from the above-mentioned thermoplastic resin composition 1A, comprising fluoropolymer filler 1B, inorganic filler 1B and adhesive resin 1B, and optionally may comprise organic solvent 1B.

[0123] The description of each component of such thermoplastic resin compositions 1A and 1B is the same as that described in the first thermoplastic resin composition (C1) above, and therefore is omitted.

[0124] The aforementioned metal foils 1A and 1B can be used without particular restriction, as long as they are common metal compositions used in metal laminates or printed circuit boards in the art. For example, each metal foil can be a metal film or an alloy film of two or more metals selected from the group consisting of copper (Cu), iron (Fe), nickel (Ni), titanium (Ti), aluminum (Al), silver (Ag), and gold (Au). Preferably, the first metal foil 13A can be a copper foil with excellent conductivity and low cost. In this case, there can be no limitation on the use of common copper foils known in the art, and all copper foils manufactured by rolling and electrolysis can be used.

[0125] The surface roughness of the metal foils 1A and 1B mentioned above is not particularly limited; for example, each can be about 0.5 to 3 μm.

[0126] Furthermore, the thickness of the metal foils 1A and 1B mentioned above is not particularly limited. Considering the thickness and mechanical properties of the metal laminate, it can be in the range of about 1 to 50 μm, specifically in the range of about 1 to 30 μm.

[0127] The above-mentioned direct coating (coating) methods are not particularly limited. For example, there are roll-to-roll coating methods, specifically comma coating, slot die coating, curtain coating, and spraying.

[0128] In the drying process of the above-mentioned resin compositions 1A and 1B, the thermoplastic resin compositions 1A and 1B are dried, especially to remove organic solvents from the compositions. This drying process can be carried out at a temperature of about 100 to 180°C for about 3 to 30 minutes. As a result, a dried film of the resin composition can be formed on each metal foil. Thus, the present invention dries each resin composition only before the heating and pressurizing processes of the first and second unit components, without performing a high-temperature sintering process above 350°C.

[0129] The first and second unit components obtained as described above are stacked separately and then heated and pressurized. However, they are stacked in such a way that the dried films of each unit component are in contact with each other. Alternatively, a fibrous substrate may be disposed between the dried films.

[0130] For example, after the first and second unit components are stacked on both sides of a fiber-containing substrate continuously supplied from a fiber-containing substrate supply roller, they can be hot-pressed at 300~340°C. At this time, the unit components are continuously supplied in such a way that the dried film of each unit component is in contact with the fiber-containing substrate while being stacked and hot-pressed.

[0131] The description of the fiber-containing substrate is the same as that described in the first embodiment section, and therefore is omitted.

[0132] During the aforementioned hot pressing process, a hot pressing device, a pair of pressure heating rollers, or a belt press can be used. In this case, a pressure of approximately 10-50 kgf / cm² can be achieved per unit length of 1 meter. 3 The film is heated / pressurized at a temperature of approximately 250-400°C for about 1-2 hours under pressure (e.g., linear pressure). Through this hot-pressing process, each dried film is (completely) cured, thereby obtaining a first metal laminate comprising a first A metal foil, a first thermoplastic resin layer, and a first B metal foil, and optionally further comprising a fiber-containing substrate disposed within the first thermoplastic resin layer. At this time, the first thermoplastic resin layer is a cured film with minimized internal pores and is an insulating layer in a stabilized state.

[0133] The first metal laminate in roll form, as described above, can then be manufactured into a first circuit board 110 through hole processing steps, hole plating steps, circuit pattern forming steps, etc., which are commonly known in the art. For example, after a plurality of holes are continuously formed on the first metal laminate continuously supplied by a roll-to-roll device, each hole is plated, and a photoresist film is laminated on a metal foil (e.g., copper foil) containing the plating film, followed by exposure, development, and then etching to form a first circuit pattern 112. Thus, a first circuit board 110 comprising a first thermoplastic resin layer 111 and first circuit patterns 112 respectively disposed on both sides of the first thermoplastic resin layer 111 can be obtained.

[0134] There are no particular limitations on the equipment used for hole processing, as long as it can create holes in the metal laminate. Examples include metal stamping, rotary stamping, and laser devices.

[0135] Alkaline developing solutions that can be used in the above-mentioned developing process include: aqueous solutions of quaternary ammonium hydroxides such as tetramethylammonium hydroxide and tetraethylammonium hydroxide; aqueous solutions of amines such as ammonia, ethylamine, diethylamine, and triethylamine, but are not limited to these.

[0136] There are no particular limitations on the etching solutions that can be used in the above etching process, as long as they are commonly used in the art. For example, the following etching solutions can be used alone or in appropriate combinations: hydrogen peroxide / hydrochloric acid (H2O2 / HCl) etching solution, copper chloride (CuCl2), ferric chloride (FeCl3) and other copper etching solutions; or CNNBSA (3-nitrobenzenesulfonic acid) / PEI (polyethylenimine) etc.

[0137] Step S200: Preparation steps for metal laminates

[0138] A metal laminate 120a is prepared, comprising a metal foil 122a and a dried film 121a of a thermoplastic resin composition (C2) disposed on one side of the metal foil 122a. This step S200 is not sequential with step S100 described above.

[0139] The metal laminate (hereinafter referred to as "second metal laminate") 120a obtained in step S200 above is in roll form and includes: metal foil 122a; and a dried film (hereinafter referred to as "second dried film") 121a of a second thermoplastic resin composition (C2) disposed on one side of the metal foil 122a.

[0140] Such a second metal laminate 120a can be manufactured by a variety of methods known in the art.

[0141] For example, by directly coating one side of the second thermoplastic resin composition (C2) onto one side of the second metal foil 122a and drying it, a second metal laminate 120a comprising the second metal foil 122a and the second dried film 121a can be obtained. In this case, when using a roll-to-roll apparatus, the aforementioned second dried film 121a can be continuously formed on the second metal foil 122a continuously supplied from the metal foil supply roller, thereby obtaining a roll-shaped second metal laminate 120a.

[0142] The second metal foil 122a described above may be different from or the same as the first metal foils 1A and 1B described above. The description of such a second metal foil 122a is the same as that described in the section on the first metal foils 1A and 1B described above, and is therefore omitted.

[0143] The aforementioned dry film 121a is obtained by drying the second thermoplastic resin composition, and subsequently becomes the second thermoplastic resin layer 121 through a hot pressing process.

[0144] The second thermoplastic resin composition (C2) may comprise a second fluororesin filler, a second inorganic filler, and a second adhesive resin. Optionally, the second thermoplastic resin composition (C2) may further comprise a second organic solvent.

[0145] Similar to the first fluororesin filler, the second fluororesin filler is a particulate organic filler, such as powder, that is solid at room temperature (approximately 20±5°C). During the drying of the second thermoplastic resin composition (C2), this second fluororesin filler, while maintaining its particle morphology, is bonded together with the second inorganic filler using a second adhesive resin. Subsequently, it is melted under high temperature and pressure and incorporated into the second thermoplastic resin layer 121 as a polymer matrix component. Therefore, the second fluororesin filler not only achieves low dielectric constant and low dielectric loss characteristics in the second thermoplastic resin layer but also improves heat resistance.

[0146] Examples of second fluororesin fillers that can be used in this invention are the same as those described in the section on first fluororesin fillers, and are therefore omitted.

[0147] The composition of the second fluororesin filler may be the same as or different from that of the first fluororesin filler. However, in order to directly attach the first circuit board 110 to the second metal laminate 120a without using an adhesive sheet, and to make the MFR of the second dry film 121a greater than the MFR of the first thermoplastic resin layer 111, it is preferable that the MFR of the second fluororesin filler is greater than the MFR of the first fluororesin filler.

[0148] As an example, the MFR of the second fluoropolymer filler can be in the range of 2 to 20 times that of the MFR of the first fluoropolymer filler.

[0149] As another example, the MFR of the aforementioned second fluororesin filler is in the range of 0.01 to 40 g / 10 min at a temperature of 372°C and a load of 5 kg, and is greater than the MFR of the first fluororesin filler. Here, the MFR (Melt Flow Rate) of the second fluororesin is the total amount of resin extruded within 10 minutes, measured according to ISO 12086-2 at 372°C and 5 kg. When the second fluororesin is a mixture of two or more types, the MFR of the mixture is measured.

[0150] The aforementioned second fluororesin filler may comprise two or more fluororesin fillers with different MFRs. As an example, the second fluororesin filler may comprise: a second A fluororesin (e.g., PTFE) having an MFR of approximately 0.01 to 1 g / 10 min at a temperature of 372°C and a load of 5 kg; and a second B fluororesin having an MFR of approximately 1 to 5 g / 10 min. In this case, the content of the second A fluororesin filler may be equal to or less than twice the content of the second B fluororesin filler.

[0151] As an example, the second fluoropolymer filler may contain PFA and PTFE. In this case, the ratio of PFA to PTFE (PFA:PTFE) may be 20:80 to 80:20 by weight, but is not limited to this.

[0152] As another example, the second fluoropolymer filler may contain: (a) PTFE; (b) one or more selected from the group consisting of PFA and FEP. In this case, the ratio of PTFE to PFA and / or FEP (PTFE:PFA and / or FEP) can be a weight ratio of 1:1 to less than 2:1. Furthermore, when PTFE is used together with PFA and FEP as the second fluoropolymer filler, the content of PFA can be adjusted to be equal to or less than the content of FEP, so that the MFR of the second thermoplastic resin layer 121 is greater than the MFR of the first thermoplastic resin layer. Here, PFA and / or FEP means PFA, or FEP, or a mixture of PFA and FEP.

[0153] As another example, the first fluoropolymer filler may comprise: (a) PTFE; and (b) PFA, wherein the content of PTFE may be greater than the content of PFA. The ratio of PTFE to PFA used (PTFE:PFA) may be a weight ratio of 1:1 to less than 2:1.

[0154] In addition, the average particle size D of the second fluororesin filler 50 The particle size can be in the range of approximately 5 to 30 μm. When the second fluororesin filler has the aforementioned average particle size, the second fluororesin filler is not only uniformly dispersed in the second thermoplastic resin composition (C2) without agglomeration, but the processability of the second thermoplastic resin composition (C2) after coating can also be improved. In this invention, as the second fluororesin filler, a single fluororesin filler with the same average particle size can be used, or two or more fluororesin fillers with different average particle sizes can be mixed. Here, the average particle size D of the second fluororesin filler... 50 It can be determined according to the ASTM D4464-10 test method.

[0155] According to one example, the second fluororesin filler may include: an average particle size D 50 The second type of fluororesin filler has a particle size of 20 to 30 μm; and the average particle size D 50 The second-generation fluoropolymer is 5 to 10 μm thick.

[0156] Furthermore, the second fluoropolymer filler can exhibit a relative permittivity (Dk) of approximately 2.0 to 2.1 and a dielectric loss tangent (Df) of 0.0001 to 0.002 at 25°C and 10 GHz. Thus, due to the low dielectric properties of the second fluoropolymer filler, low dielectric constant and low dielectric loss characteristics of the second thermoplastic resin layer 121 can be achieved. Here, the relative permittivity (Dk) and dielectric loss tangent (Df) of the second fluoropolymer filler were measured at 25°C and 10 GHz using the split postdielectric resonator (SPDR) method (IEC 61189-2-721 test method).

[0157] Furthermore, the shape of the second fluoropolymer filler is not particularly limited; for example, it can be spherical, flake-like, dendrite-like, conical, pyramidal, or amorphous. These can be used alone or in combination. According to one example, the second fluoropolymer filler can be spherical. In this case, the surface area of ​​the second fluoropolymer filler is minimized, thus improving the processing characteristics of the second thermoplastic resin composition and imparting isotropic properties to the second thermoplastic resin layer.

[0158] In the second thermoplastic resin composition (C2) of the present invention, the content of the second fluororesin filler can be in the range of about 50 to 80% by weight, based on the total amount of the resin composition. By adjusting the content of the second fluororesin filler within the aforementioned range, the resin composition can form a resin layer with a low dielectric constant.

[0159] As an example, when the second fluororesin filler contains PTFE and PFA in a weight ratio of 2:1, and the content of the second fluororesin filler is adjusted to about 50% by weight, the content of the second inorganic filler is adjusted to about 45% by weight, and the content of the second adhesive resin is adjusted to about 5% by weight, the MFR of the second thermoplastic resin layer can be 5 g / 10 min.

[0160] As another example, when the second fluororesin filler contains PTFE and PFA in a 1:1 weight ratio, and the content of the second fluororesin filler is adjusted to about 80% by weight, the content of the second inorganic filler is adjusted to about 17% by weight, and the content of the second adhesive resin is adjusted to about 3% by weight, the MFR of the second thermoplastic resin layer can be less than about 1 g / 10 min.

[0161] In the second thermoplastic resin composition (C2) of the present invention, the second inorganic filler reduces the difference in coefficient of thermal expansion (CTE) between the second thermoplastic resin layer 121 and other layers [e.g., the second circuit pattern 122], thereby improving the warpage characteristics, low expansion, mechanical strength (toughness), and low stress of the second circuit substrate 120.

[0162] The second inorganic packing may be the same as or different from the first inorganic packing in at least one of its composition, size (e.g., maximum particle size, average particle size), and shape. The description of such a second inorganic packing is the same as that described in the section on the first inorganic packing, and is therefore omitted.

[0163] In the second thermoplastic resin composition (C2) of the present invention, the content of the second inorganic filler can be in the range of about 20% to 50% by weight, specifically about 30% to 45% by weight, based on the total amount of the resin composition. When the content of the second inorganic filler is less than about 20% by weight, the effect of reducing the dielectric constant may not be significant; while when the content of the second inorganic filler is greater than about 50% by weight, the moldability of the resin composition may decrease.

[0164] According to one example, when the first fluororesin filler in the first thermoplastic resin composition and the second fluororesin filler in the second thermoplastic resin composition are identical in composition and content, the content of the second inorganic filler in the second thermoplastic resin composition is adjusted to be less than the content of the first inorganic filler in the first thermoplastic resin composition (C1). In this case, the MFR of the second dry film 121a can be adjusted to be greater than the MFR of the first thermoplastic resin layer 111. Therefore, the present invention enables the first circuit board 110 and the second circuit board 120 to be directly attached without an adhesive sheet.

[0165] There is no particular limitation on the method of coating (applying) the above-mentioned second thermoplastic resin composition. For example, there is roll-to-roll coating, specifically comma coating, slit coating, curtain coating, and spraying.

[0166] In the above-described drying process, the second thermoplastic resin composition is dried, particularly to remove the organic solvent from the composition. This drying process can be carried out at a temperature below approximately 100°C, specifically at approximately 30 to 80°C, for approximately 1 to 5 minutes. As a result, a second metal laminate 120a is obtained on the second metal foil 122a having a second dried film 121a formed on it after the second thermoplastic resin composition (C2) has been dried. Thus, the present invention only dries the second thermoplastic resin composition without performing a high-temperature sintering process above 300°C. Therefore, the second dried film 121a obtained through the above-described drying process can be a sponge-like insulating layer with numerous internal pores.

[0167] However, in this invention, the MFR of the second dry film 121a is adjusted to be greater than the MFR of the first thermoplastic resin layer 111 of the first circuit board 110. Therefore, in this invention, the second metal laminate 120a can be bonded to the first circuit board 110 obtained in step S10 without an adhesive sheet in step S40, thus preventing a decrease in the dimensional stability of the first circuit board 110.

[0168] Step S300: Formation of the first multilayer laminate

[0169] The first circuit board 110 obtained in step S100 is stacked on both sides of the carrier film 10 to form a first multilayer laminate. The first multilayer laminate formed in this step may have a structure in which the first circuit board 110 / carrier film 10 / first circuit board 110 are stacked in that order.

[0170] like Figure 1 As shown in Part I, when using a roll-to-roll device, the carrier film 10 is continuously supplied from the carrier film supply roller, and the first circuit board 110 is continuously supplied from the first circuit board supply roller, so the first multilayer laminate can also be continuously formed.

[0171] The above-mentioned lamination process can be carried out using a pair of laminating rollers.

[0172] The carrier film 10 is a release film for interlayer separation (peeling), which enables the first circuit board 110 to adhere stably on the one hand, and allows the first circuit board to be easily desorbed (separated) by a predetermined external force on the other hand.

[0173] The carrier membrane 10 used in this invention can be a polyimide (PI) membrane, but is not limited thereto.

[0174] A release layer may be disposed on the surface of such a carrier film 10. The release layer enables the first circuit pattern 111 or the first thermoplastic resin layer 112 of the first circuit board 110 to be easily separated from the carrier film 10 while maintaining its shape and without damage.

[0175] The release agent for the aforementioned release layer is not particularly limited; examples include epoxy-based release agents, release agents composed of fluororesins, silicone-based release agents, alkyd resin-based release agents, and water-soluble polymers. Furthermore, powdered fillers, such as silicone and silica, can be included as components of the release layer as needed. In this case, two types of particulate powder fillers can be mixed, and their average particle size can be appropriately selected considering the resulting surface roughness.

[0176] The thickness of such a release layer can be appropriately adjusted within the range known in the art.

[0177] In this invention, the thickness of the carrier membrane 10 is not particularly limited and can be adjusted within the range known in the art, for example, it can be about 25 to 100 μm.

[0178] The release force of such a carrier film 10 is not particularly limited, for example, it can be about 1 to 10 gf / inch.

[0179] There are no particular limitations on the method for forming the release layer; known methods such as hot pressing, hot roller lamination, extrusion lamination, coating with coating liquid, and drying can be used.

[0180] Step S400: Formation of the second multilayer laminate

[0181] The second metal laminate 120a obtained in step S200 is stacked on both sides of the first multilayer laminate obtained in step S300 to form a second multilayer laminate. At this time, the second dry film 121a of the second metal laminate 120a is in contact with the first circuit board 110.

[0182] like Figure 1 As shown in Part II, when using a roll-to-roll device, a second metal laminate 120a continuously supplied from a metal laminate supply roller can be stacked on both sides of the first multilayer laminate continuously supplied in step S300 to continuously form a second multilayer laminate.

[0183] The above-mentioned lamination process can be carried out using a pair of laminating rollers.

[0184] The second B multilayer laminate obtained in step S400 above may include: a first B multilayer laminate, which includes a carrier film 10 and a first circuit board 110 respectively disposed on both sides of the carrier film 10; and a second metal laminate 120a respectively disposed on both sides of the first B multilayer laminate. Specifically, the second B multilayer laminate may have a structure in which the layers are stacked in the following order: second metal foil 122a / second dry film 121a / first circuit pattern 112 / first thermoplastic resin layer 111 / first circuit pattern 112 / carrier film 10 / first circuit pattern 112 / first thermoplastic resin layer 111 / first circuit pattern 112 / second dry film 121a / second metal foil 122a. In this case, the second dry film 121a can contact not only the first circuit pattern 112, but also the first thermoplastic resin layer 111.

[0185] Optionally, protective metal foil 20 can be laminated on both sides of the second multilayer laminate obtained in step S400 above.

[0186] like Figure 1 As shown in Part III, when using a roll-to-roll device, protective metal foil 20 continuously supplied from the protective metal foil supply roller can be stacked on both sides of the second multilayer laminate obtained in step S400 above to continuously form the second B multilayer laminate.

[0187] The protective metal foil 20 used in this invention is not particularly limited, and may be a metal film or an alloy film of two or more metals selected from the group consisting of copper (Cu), iron (Fe), nickel (Ni), titanium (Ti), aluminum (Al), silver (Ag), and gold (Au). As an example, the protective metal foil 20 may be a copper foil. In this case, the copper foil may be any conventional copper foil known in the art, and all copper foils manufactured by rolling and electrolysis methods may be used without limitation.

[0188] The aforementioned lamination process of the protective metal foil can be carried out using a pair of laminating rollers.

[0189] Step S500: Hot pressing step of the second B multilayer laminate

[0190] The second multilayer laminate obtained in step S400 above is hot-pressed. At this time, the second multilayer laminate can also be used instead of the second multilayer laminate.

[0191] Since both the second dry film 121a and the first thermoplastic resin layer 111 within the second multilayer laminate contain thermoplastic components, they can undergo plastic deformation under heat. Therefore, when the second multilayer laminate is hot-pressed, the second dry film 121a melts upon heating, becomes fluid, and diffuses. At this time, the first thermoplastic resin layer 111 may or may not melt. If the first thermoplastic resin layer 111 also melts upon heating, since the MFR of the first thermoplastic resin layer 111 is smaller than that of the second dry film 121a, unlike the second dry film 121a, only the resin layer at the interface with the second dry film 121a becomes fluid and diffuses. The components of the diffused second dry film 121a mix with the components of the first thermoplastic resin layer 111 at the interface, thereby filling the spaces between the first circuit patterns 112 without air bubbles. Subsequently, when the second multilayer laminate is cooled, the molten second dry film 121a solidifies into a second thermoplastic resin layer 121, and the molten first thermoplastic resin layer 111 also solidifies again. At this time, the second thermoplastic resin layer 121 and the first thermoplastic resin layer 111 are adhered and integrated like a single film without any dissimilar interface. Therefore, the printed circuit board of the present invention may include a first circuit board 110 and a second circuit board 120 that are directly attached to each other without an adhesive sheet.

[0192] like Figure 1 As shown in section IV, this step S500 can be performed using a roll-to-roll device. In this case, the second multilayer laminate supplied continuously in step S400 above can be continuously heat-pressed.

[0193] The hot pressing process described above can be performed using a pair of heating rollers or a belt press consisting of multiple pairs of heating rollers. In particular, when using a belt press, since the pressure and temperature of each heating roller can be adjusted separately, the temperature and pressure of the compression molding step and the sintering step can be adjusted differently.

[0194] The above step S500 may include: (S510) compressing the second B multilayer laminate obtained in step S400; and (S520) sintering the compressed multilayer laminate.

[0195] The compression molding step described above (hereinafter referred to as "step S510") is a low-temperature and high-pressure compression molding process. In step S510, when pressure is applied to the second drying film 122a, the second fluororesin filler in the second drying film 122a is compressed due to the high pressure, thereby removing air bubbles between the fillers.

[0196] Step S510 described above can be performed at a pressure ranging from approximately 3 to 5 MPa for approximately 30 to 90 minutes. During such compression molding, the multilayer laminate can be preheated. The preheating temperature is not particularly limited, but is preferably lower than the melting point (Tm) of the second dried film, specifically lower than the melting point (Tm) of the second fluoropolymer filler. As an example, the preheating temperature can be lower than 300°C, specifically approximately 200 to 280°C. In this case, the actual temperature standard applied to the actual product and the actual pressing conditions can vary.

[0197] The sintering step described above (hereinafter referred to as "step S520") is preferably performed at a lower pressure than that of the compression molding step described above. This minimizes the flowability of the first thermoplastic resin layer 111 during sintering, thereby ensuring dimensional stability. According to one example, step S42 can be performed at a pressure less than 2 MPa, specifically at a pressure of about 0.5 to 1 MPa.

[0198] Such step S520 may include: (S521) heat-treating the multilayer laminate after compression molding at a temperature above the melting point (Tm) of the second dry film and at a pressure lower than the pressure during compression molding; (S522) stabilizing the multilayer laminate after heat treatment by applying pressure to the pressure during compression molding at a temperature lower than the melting point (Tm) of the second dry film; and (S523) cooling the stabilized multilayer laminate.

[0199] As an example of the aforementioned heat treatment temperature, it can be approximately 305°C or higher, specifically approximately 330~380°C, and more specifically approximately 330~350°C. According to one example, the aforementioned heat treatment step [hereinafter referred to as "step S521"] can be performed at a temperature of approximately 305°C or higher, at a pressure lower than the pressure used during the aforementioned compression molding, for example, at a pressure of approximately 0.5~2 MPa, for approximately 30~90 minutes. In this case, the fluidity of the second fluoropolymer filler in the second dry film 121a is further improved, thereby further enhancing the diffusion effect.

[0200] The aforementioned stabilization step [hereinafter referred to as "step S522"] can be performed at a temperature below approximately 300°C, specifically at approximately 200-280°C, and more specifically at approximately 250-280°C. According to one example, in the stabilization step, pressure is applied at a temperature below 300°C to the pressure used in the compression molding process, for example, to a pressure of approximately 3-5 MPa, to stabilize the heat-treated multilayer laminate. This ensures the thickness stability of each resin layer.

[0201] The cooling step described above [hereinafter referred to as "step S523"] can be performed at the same pressure as the stabilization step while cooling the stabilized multilayer laminate.

[0202] Step S600: Steps for forming the second circuit pattern

[0203] Although not illustrated, the second metal foil 122a of the second multilayer laminate after hot pressing in step S500 is processed into a second circuit pattern 122. Through this step S600, the present invention can obtain a third multilayer laminate having a structure in which the layers are stacked in the order of second circuit substrate 120 / first circuit substrate 110 / carrier film 10 / first circuit substrate 110 / second circuit substrate 120.

[0204] In step S600 above, after a photoresist film or the like is laminated on the second metal foil 122a, exposure and development are performed, followed by etching to form the second circuit pattern 122.

[0205] The descriptions of the above exposure, development, and etching processes are the same as those described in step S50 above, and are therefore omitted.

[0206] In the above exposure process, cured and uncured areas are formed by exposure. Depending on whether the photoresist film is positive or negative, the unexposed or exposed areas are subsequently removed by developing solution.

[0207] Such exposure processes can utilize excimer lasers, far-ultraviolet light, ultraviolet light, visible light, electron beams, X-rays or gamma rays (wavelength approximately 436 nm), i-rays (wavelength approximately 365 nm), h-rays (wavelength approximately 405 nm), or a mixture thereof.

[0208] In the above-mentioned developing process, an alkaline developing solution is used to develop the partially exposed photoresist film to remove uncured areas. Examples of alkaline developing solutions include: aqueous solutions of quaternary ammonium hydroxides such as tetramethylammonium hydroxide and tetraethylammonium hydroxide; aqueous solutions of amines such as ammonia, ethylamine, diethylamine, and triethylamine, etc., but not limited to these.

[0209] In the above etching process, the second metal foil portion after a certain area of ​​the photoresist film has been removed is etched with an etching solution to form the second circuit pattern 122. Non-limiting examples of the etching solution include: hydrogen peroxide / salt (H2O2 / HCl) etching solution; copper etching solutions such as copper chloride (CuCl2) and ferric chloride (FeCl3); or CNNBSA (3-nitrobenzene sulfonic acid) / PEI (polyethylenimine), which can be used alone or in appropriate combinations of two or more.

[0210] Although not illustrated, in this invention, before or after forming the second circuit pattern, a plurality of holes H can be processed on the hot-pressed second B multilayer laminate, and then the plurality of holes are plated to form through holes.

[0211] There are no particular limitations on the equipment used for hole processing, as long as it can create holes in the metal laminate. Examples include metal stamping, rotary stamping, and laser devices.

[0212] There are no particular limitations on the method for forming the above-mentioned coating; it can be carried out in accordance with the usual methods known in the art.

[0213] Step S700: Separation of the multilayer printed circuit board

[0214] Separating the carrier film 10 and the first circuit substrate 110 from the third multilayer laminate obtained in step S600 above, two multilayer printed circuit substrates with the first circuit substrate 110 and the second circuit substrate 120 stacked on them can be obtained simultaneously.

[0215] like Figure 1 As shown in section V, when the first circuit boards 110 on both sides of the third multilayer laminate continuously supplied from step S600 are separated (desorbed) from the carrier film 10, two multilayer printed circuit boards with the first circuit boards 110 and the second circuit board stacked on top of each other can be obtained at one time. The multilayer printed circuit boards can be wound on a take-up roller for storage and movement.

[0216] According to one example, such as Figure 2 As shown, the multilayer printed circuit board 100A manufactured by the present invention does not include a bonding sheet, and comprises: a first circuit board 110 including a first thermoplastic resin layer 111 and a first circuit pattern 112 disposed on at least one side of the first thermoplastic resin layer 111; and a second circuit board 120 including a second thermoplastic resin layer 121 disposed on at least one side of the first circuit board 110 and a second circuit pattern 122 disposed on one side of the second thermoplastic resin layer 121, wherein the melt flow rate (MFR) of the second thermoplastic resin layer 111 is greater than the MFR of the first thermoplastic resin layer 121. Optionally, the first circuit board 110 may further include a fiber-containing substrate 113 (see reference) embedded in the first thermoplastic resin layer 111. Figure 3 ).

[0217] Although not illustrated, the multilayer printed circuit board 100A of the present invention may further include vias formed through at least one of the first thermoplastic resin layer 111 and the second thermoplastic resin layer 121, electrically connecting the first circuit patterns 112 with each other and / or the first circuit pattern 112 with the second circuit pattern 122.

[0218] A protective metal foil 20 may be laminated on the second circuit board 120 of the aforementioned separated multilayer printed circuit board. In this case, the protective metal foil 20 can be further separated from the multilayer printed circuit board. The separated protective metal foil 20 can be rewound on a take-up roller for reuse. However, the protective metal foil 20 can also be separated from the third multilayer laminate before separating the multilayer printed circuit board.

[0219] On the other hand, the carrier film 10, which is separated from the multilayer printed circuit board, can be rewound onto the take-up roller and reused.

[0220] Step S800: Repeating the process from the formation step of the first multilayer laminate to the separation step of the multilayer printed circuit board. OK

[0221] Optionally, after the above-described hole plating step, the present invention may further include: preparing an nth metal laminate comprising an nth metal foil and an nth dry film of a thermoplastic resin composition disposed on one side of the nth metal foil. After the separation step of the multilayer printed circuit board, the steps from forming the first multilayer laminate to the separation step of the multilayer printed circuit board may be repeated once or more (here, n is an integer of 3 or more, specifically an integer from 3 to 10). In this case, the multilayer printed circuit board separated in step S700 can be used to replace the first circuit board 110 to form the first multilayer laminate, and the (n-1)th metal laminate can be used to replace the metal laminate 120a to form the second multilayer laminate. However, in order to manufacture a multilayer printed circuit board in which each circuit board is attached without an adhesive sheet, the present invention is adjusted such that the MFR of each dry film gradually increases as it moves from the first thermoplastic resin layer 111 toward the nth dry film.

[0222] For example, after step S700, the present invention can prepare a third metal laminate comprising a third metal foil and a third dry film of a third thermoplastic resin composition disposed on one side of the third metal foil. At this time, the MFR of the third dry film is adjusted to be greater than that of the second dry film. Then, the multilayer printed circuit board obtained in step S700 is stacked on both sides of the carrier film 10 to form a first multilayer laminate, and then the prepared third metal laminate is stacked on both sides of the first multilayer laminate to form a second multilayer laminate. Next, after hot pressing the second multilayer laminate, the third metal foil is processed into a third circuit pattern, and holes are machined and plated, thereby obtaining a third multilayer laminate having a structure of third circuit board 130 / second circuit board 120 / first circuit board 110 / carrier film 10 / first circuit board 110 / second circuit board 120 / third circuit board 130. Afterwards, by performing the above step S700, two multilayer circuit boards, in which the first circuit board, the second circuit board, and the third circuit board are stacked sequentially, can be obtained simultaneously.

[0223] Alternatively, protective metal foil 20 can be stacked on both sides of the second multilayer laminate, then hot-pressed, and then the third metal foil can be processed into a third circuit pattern, and holes can be processed and plated.

[0224] Alternatively, by repeatedly performing the preparation step of the nth metal laminate, the formation step of the second multilayer laminate, the hot pressing step, the circuit pattern formation step, the hole processing step, and the hole plating step, a third multilayer laminate with a structure having an nth circuit substrate / ... / third circuit substrate 130 / second circuit substrate 120 / first circuit substrate 110 / carrier film 10 / first circuit substrate 110 / second circuit substrate 120 / third circuit substrate 130 / ... / nth circuit substrate can be manufactured, where n is an integer of 3 or more, specifically an integer from 3 to 10. The nth metal laminate includes an nth metal foil and an nth dried film of a thermoplastic resin composition disposed on one side of the nth metal foil. At this time, the adjustment is made such that the MFR of each dried film gradually increases as it moves from the first thermoplastic resin layer to the nth dried film. Afterwards, by performing the above step S700, two multilayer circuit substrates having a first circuit substrate / second circuit substrate / third circuit substrate / ... / nth circuit substrate stacked sequentially can be obtained simultaneously.

[0225] However, in this invention, in order to allow the nth drying film to adhere directly to the (n-1)th thermoplastic resin layer without an adhesive sheet, the adjustment is such that the MFR of each drying film gradually increases as it moves from the first thermoplastic resin layer towards the nth drying film side (where n is an integer of 3 or more, specifically an integer from 3 to 10). For example, the MFR of the second thermoplastic resin layer 121 is greater than the MFR of the first thermoplastic resin layer 111, and the MFR of the third drying film is greater than the MFR of the second thermoplastic resin layer 121.

[0226] According to one example, as the flow rate moves from the first thermoplastic resin layer 121 towards the nth dry film side, the MFR of the nth dry film can increase by 2 to 10 times the MFR of the (n-1)th thermoplastic resin layer. For example, as the flow rate moves from the first thermoplastic resin layer 111 towards the third dry film side, the MFR of the second thermoplastic resin layer 121 can increase by 2 to 10 times the MFR of the first thermoplastic resin layer 111, and the MFR of the third dry film 131 can increase by 2 to 10 times the MFR of the second thermoplastic resin layer 121.

[0227] For example, the MFR of the first thermoplastic resin layer 111 can be in the range of 0.01 to 1 g / 10 min at a temperature of 372°C and a load of 5 kg, the MFR of the second thermoplastic resin layer 121 can be in the range of greater than 1 g / 10 min to 5 g / 10 min at a temperature of 372°C and a load of 5 kg, and the MFR of the third dry film can be 5 to 50 g / 10 min at a temperature of 372°C and a load of 5 kg, specifically in the range of 20 to 30 g / 10 min.

[0228] According to another example, as the drying film moves from the first thermoplastic resin layer 110 to the nth drying film side, the melting point (Tm) of each drying film can gradually decrease. In this case, it can be adjusted so that as the drying film moves from the first thermoplastic resin layer 110 to the nth drying film side, the content of fluoropolymer fillers with low melting points (Tm) in the resin composition forming each drying film gradually increases.

[0229] For example, the first thermoplastic resin composition forming the first thermoplastic resin layer 111 may mainly contain PTFE (Tm: about 317~337°C) as the first fluororesin filler, the second thermoplastic resin composition forming the second thermoplastic resin layer 121 may mainly contain PFA (Tm: about 302~310°C) as the second fluororesin filler, and the third thermoplastic resin composition forming the third dry film 131 may mainly contain FEP (Tm: 260~282°C) as the third fluororesin filler. That is, the content ratio in each resin layer is adjusted such that as the resin moves from the first thermoplastic resin layer 111 to the third dry film side, the content ratio increases in the order of PTFE -> PFA -> FEP.

[0230] According to another example, the first thermoplastic resin composition forming the first thermoplastic resin layer 111 contains PTFE (Tm: about 317~337°C) and PFA (Tm: about 302~310°C) as the first fluororesin filler, wherein the content of PTFE can be more than that of PFA (for example, PTFE:PFA = 2:1~10:1 by weight). The second thermoplastic resin composition forming the second thermoplastic resin layer 121 contains PFA (Tm: about 302~310°C) and PTFE (Tm: about 317~337°C) as the second fluororesin filler in a weight ratio of 1:1 to less than 1:2. The third thermoplastic resin composition forming the third dry film contains FEP (Tm: 260~282°C) and PFA (Tm: about 302~310°C) as the third fluororesin filler, wherein the content of FEP can be more than that of PFA (for example, FEP:PFA = 1:1~10:1 by weight).

[0231] According to another example, when the composition and content of fluororesin filler in the first thermoplastic resin composition to the nth thermoplastic resin composition are the same, it can be adjusted so that as the material moves from the first thermoplastic resin layer 110 to the nth drying film side, the content of inorganic filler in each drying film gradually decreases.

[0232] The multilayer printed circuit board 100B obtained by the aforementioned step 800 includes: a first circuit board 110; a second circuit board 120 respectively disposed on both sides of the first circuit board 110; and a third circuit board 130 to an nth circuit board (here, n is an integer greater than or equal to 3, specifically an integer from 3 to 10) disposed sequentially on the second circuit board 120.

[0233] As an example, such as Figure 4 As shown, the multilayer printed circuit board 100B manufactured by the present invention may include: a first circuit board 110; a second circuit board 120 disposed on both sides of the first circuit board 110; and a third circuit board 130 disposed on the second circuit board 120.

[0234] At this time, the third circuit board includes a third thermoplastic resin layer disposed on the second circuit board and a third circuit pattern disposed on one side of the third thermoplastic resin layer. The n circuit board includes an nth thermoplastic resin layer disposed on the (n-1)th circuit board and an nth circuit pattern disposed on one side of the nth thermoplastic resin layer. Furthermore, the MFR of each thermoplastic resin layer gradually increases from the first thermoplastic resin layer towards the nth thermoplastic resin layer. However, the second circuit board 120, the third circuit board 130, and the nth circuit board, which are sequentially disposed on either side of the first circuit board 110, can be omitted.

[0235] Furthermore, the multilayer printed circuit board 100B of the present invention may further include vias formed through at least any one of the first thermoplastic resin layer 111, the second thermoplastic resin layer 121, the third thermoplastic resin layer, ..., the nth thermoplastic resin layer, and electrically connecting the first circuit patterns 112 with each other, and at least any one of the first circuit patterns 112, the second circuit pattern 122, the third circuit pattern 132, ..., the nth circuit pattern with each other (where n is an integer of 3 or more, specifically an integer from 3 to 10).

[0236] As mentioned above, the present invention can not only automatically and continuously manufacture multilayer printed circuit boards without adhesive sheets through roll-to-roll processing throughout the entire process, but also shorten the manufacturing process time, improve mass production and reduce costs.

[0237] The multilayer printed circuit board manufactured in this invention achieves environmental reliability and low dielectric loss in high-frequency regions by directly bonding the circuit board with a single material without adhesive sheets to build up the layers.

[0238] Furthermore, the multilayer printed circuit board manufactured by this invention, through the thinning of the product, enables the realization of 3D-shaped circuits formed by bending and folding, thereby improving processability.

[0239] Meanwhile, the multilayer printed circuit board manufactured by this invention has excellent low-loss characteristics in the high-frequency region because each thermoplastic resin layer contains fluorine components.

Claims

1. A method for manufacturing a multilayer printed circuit board, comprising: The step of preparing a first circuit board including a first thermoplastic resin layer and a first circuit pattern disposed on at least one side of the first thermoplastic resin layer; The step of preparing a metal laminate comprising a metal foil and a dried film of a thermoplastic resin composition disposed on one side of the metal foil; The step of stacking the first circuit board on both sides of the carrier film to form a first multilayer laminate; The step of stacking the metal laminates on both sides of the first multilayer laminate to form a second multilayer laminate; The step of hot pressing the second multilayer laminate; The step of forming a second circuit pattern on the metal foil of the second multilayer laminate after hot pressing to form a third multilayer laminate; as well as The step of separating the carrier film and the first circuit substrate from the third multilayer laminate to obtain two multilayer printed circuit boards with the first circuit substrate and the second circuit substrate stacked on them, and The MFR of the dried film is adjusted to be greater than that of the first thermoplastic resin layer.

2. The method for manufacturing a multilayer printed circuit board according to claim 1, wherein, The MFR of the dried film is in the range of 10 to 100 times that of the MFR of the first thermoplastic resin layer.

3. The method for manufacturing a multilayer printed circuit board according to claim 1, wherein, The MFR of the first thermoplastic resin layer is in the range of 0.01 to 1 g / 10 min at a temperature of 372°C and a load of 5 kg.

4. The method for manufacturing a multilayer printed circuit board according to claim 1, wherein, The MFR of the dried film is greater than 1 g / 10 min and less than 5 g / 10 min at a temperature of 372°C and a load of 5 kg.

5. The method for manufacturing a multilayer printed circuit board according to claim 1, wherein, The first thermoplastic resin layer is formed of a first thermoplastic resin composition comprising a first fluororesin filler, a first inorganic filler, and a first adhesive resin. The thermoplastic resin composition comprises a second fluororesin filler, a second inorganic filler, and a second adhesive resin. The MFR of the second fluororesin filler is greater than that of the first fluororesin filler.

6. The method for manufacturing a multilayer printed circuit board according to claim 5, wherein, The MFR of the second fluororesin filler is in the range of 2 to 20 times that of the MFR of the first fluororesin filler.

7. The method for manufacturing a multilayer printed circuit board according to claim 5, wherein, The content of the second inorganic filler in the second thermoplastic resin composition is less than the content of the first inorganic filler in the first thermoplastic resin composition.

8. The method for manufacturing a multilayer printed circuit board according to claim 1, wherein, The drying film is directly attached to the first circuit board.

9. The method for manufacturing a multilayer printed circuit board according to claim 1, wherein, The first thermoplastic resin layer contains a fiber-containing substrate.

10. The method for manufacturing a multilayer printed circuit board according to claim 1, wherein, The hot pressing step includes: The step of compressing and molding the second multilayer laminate; and The step of sintering the second multilayer laminate after compression molding described above. The sintering step is performed at a lower pressure than the compression molding step.

11. The method for manufacturing a multilayer printed circuit board according to claim 10, wherein, The compression molding step is performed under a pressure ranging from 3 to 6 MPa.

12. The method for manufacturing a multilayer printed circuit board according to claim 10, wherein, The sintering step includes: The step of heat-treating the second multilayer laminate after compression molding at a temperature above the melting point Tm of the dried film and at a pressure lower than that during compression molding; The step of stabilizing the second multilayer laminate after the above heat treatment by applying pressure to the pressure during compression molding at a temperature lower than the melting point Tm of the dried film; and The step of cooling the stabilized second multilayer laminate described above.

13. The method for manufacturing a multilayer printed circuit board according to claim 1, wherein, Before or after forming the second circuit pattern, it further includes: The step of machining multiple holes in the second multilayer laminate; and The step of plating the plurality of holes to form through holes.

14. The method for manufacturing a multilayer printed circuit board according to claim 13, further comprising: The steps of preparing an nth metal laminate comprising an nth metal foil and an nth dry film of a thermoplastic resin composition disposed on one side of the nth metal foil. After the separation step of the multilayer printed circuit board, The step of forming the first multilayer laminate to the separation step of the multilayer printed circuit board is repeated once or multiple times, and The first multilayer laminate is formed by replacing the first circuit board with the separated multilayer printed circuit board. The second multilayer laminate is formed by replacing the metal laminate with the nth metal laminate. Furthermore, the adjustment is made such that as the material flow rate (MFR) of each dried film gradually increases from the first thermoplastic resin layer towards the nth dried film. n is an integer greater than or equal to 3.

15. The method for manufacturing a multilayer printed circuit board according to claim 14, wherein, As the flow moves from the first thermoplastic resin layer toward the nth drying film side, the MFR of each drying film gradually increases by a factor of 2 to 10.

16. The method for manufacturing a multilayer printed circuit board according to claim 14, wherein, As the temperature moves from the first thermoplastic resin layer toward the nth drying film side, the melting point Tm of each drying film gradually decreases.

Images