Multilayer printed circuit board and method for manufacturing same

Abstract

The present invention relates to a multilayer printed circuit board and a method for manufacturing same. The multilayer printed circuit board comprises: a first circuit board including a first thermoplastic resin layer and a first circuit pattern disposed on at least one surface of the first thermoplastic resin layer; and a second circuit board including a second thermoplastic resin layer disposed on at least one surface of the first circuit board and a second circuit pattern disposed on one surface of the second thermoplastic resin layer. The melt flow rate (MFR) of the second thermoplastic resin layer is larger than the MFR of the first thermoplastic resin layer.

Description

Multilayer printed circuit board and manufacturing method thereof

[0001] The present invention relates to a multilayer printed circuit board and a method for manufacturing the same, and more particularly, to a multilayer printed circuit board that does not include a bonding sheet and a method for manufacturing the same.

[0002] The recent advancement in electronic devices' performance is remarkable, and in particular, communication devices and computers are required to respond to higher frequencies as well as increased operating speeds. In addition, further reduction in weight, thickness, and miniaturization is also required for increased multifunctionality and portability.

[0003] For this reason, printed circuit boards used in electronic devices are increasingly required to have high-speed, low-loss signal transmission, high-density wiring, thinner structures, and lighter weight. In response to these demands, substrate materials are also becoming increasingly thinner and lighter, with lower dielectric constants and dielectric constants. To achieve this, multilayer printed circuit boards using the build-up method have been utilized.

[0004] As a material for the main insulating layer of the multilayer printed circuit board, a thermosetting resin with a high melting point, such as epoxy resin or polyimide resin, is widely used. The insulating layer made of the thermosetting resin can provide good heat resistance and insulation properties to the high-density multilayer printed circuit board. However, in order to stack each circuit board made of the thermosetting resin into multiple layers, a bonding sheet with a lower melting point or curing point than the main insulating layer is required, and additional cutting, welding, and curing processes are required for each bonding sheet. As such, since the manufacturing process and materials increase, the manufacturing cost also increases. In addition, since the thickness of the entire multilayer printed circuit board increases by the thickness of the bonding sheet used in the lamination process, the circuit may be damaged during folding processing, or the spring back characteristic is prominent due to the elasticity of the bonding sheet layer.

[0005] The present invention aims to provide a multilayer printed circuit board and a method for manufacturing the same, which not only has excellent interlayer adhesion but also has low-loss characteristics and excellent processability in a high-frequency range, even without including a bonding sheet.

[0006] In order to solve the above-mentioned problem, the present invention provides a multilayer printed circuit board including a first circuit board including a first thermoplastic resin layer and a first circuit pattern disposed on at least one surface of the first thermoplastic resin layer; and a second circuit board including a second thermoplastic resin layer disposed on at least one surface of the first circuit board and a second circuit pattern disposed on one surface of the second thermoplastic resin layer, wherein a melt flow rate (MFR) of the second thermoplastic resin layer is greater than an MFR of the first thermoplastic resin layer.

[0007] In one example, the MFR of the second thermoplastic resin layer may be 10 to 100 times greater than the MFR of the first thermoplastic resin layer.

[0008] According to another example, the MFR of the first thermoplastic resin layer may be in the range of 0.01 to 1 g / 10 min at a temperature of 372° C. and a load of 5 kg.

[0009] According to another example, the MFR of the second thermoplastic resin layer may be greater than 1 g / 10 min and less than or equal to 5 g / 10 min at a temperature of 372° C. and a load of 5 kg.

[0010] According to another example, the first thermoplastic resin layer is formed of a first thermoplastic resin composition including a first fluororesin filler, a first inorganic filler, and a first binder resin, and the second thermoplastic resin layer is formed of a second thermoplastic resin composition including a second fluororesin filler, a second inorganic filler, and a second binder resin, and the MFR of the second fluororesin filler may be greater than the MFR of the first fluororesin filler.

[0011] According to another example, the MFR of the second fluororesin filler may be in the range of 2 to 20 times that of the first fluororesin filler.

[0012] According to another example, the content of the second inorganic filler in the second thermoplastic resin composition may be less than the content of the first inorganic filler in the first thermoplastic resin composition.

[0013] In another example, the second thermoplastic resin layer is directly attached to the first circuit board.

[0014] According to another example, a fiber-containing substrate may be embedded within the first thermoplastic resin layer.

[0015] According to another example, the invention further includes third to n-th circuit boards sequentially arranged on the second circuit board, the third circuit board including a third thermoplastic resin layer arranged on the second circuit board, and a third circuit pattern arranged on one surface of the third thermoplastic resin layer, the n-th circuit board including an n-th thermoplastic resin layer arranged on the n-1-th circuit board, and an n-th circuit pattern arranged on one surface of the n-th thermoplastic resin layer, and the MFR of each thermoplastic resin layer may gradually increase from the second thermoplastic resin layer to the n-th thermoplastic resin layer, and n may be 3 or more.

[0016] According to another example, as one moves from the second thermoplastic resin layer toward the nth thermoplastic resin layer, the MFR of each thermoplastic resin layer may gradually increase by 2 to 10 times.

[0017] According to another example, as one moves from the first thermoplastic resin layer toward the nth thermoplastic resin layer, the melting point (Tm) of each thermoplastic resin layer may gradually decrease.

[0018] In addition, the present invention provides a method for manufacturing a multilayer printed circuit board, comprising: preparing a first circuit board including a first thermoplastic resin layer and a first circuit pattern disposed on at least one surface of the first thermoplastic resin layer; preparing a metal laminate including a metal foil and a dry film of a thermoplastic resin composition disposed on one surface of the metal foil; laminating the metal laminate on at least one surface of the first circuit board to form a multilayer laminate; hot pressing the multilayer laminate; and forming a second circuit pattern on the metal foil of the hot-pressed multilayer laminate; wherein the MFR of the dry film is adjusted to be greater than the MFR of the first thermoplastic resin layer.

[0019] According to an example, the hot press step includes a step of compression molding the multilayer laminate; and a step of sintering the compression molded multilayer laminate, wherein the sintering step can be performed under a lower pressure than the compression molding step.

[0020] According to another example, the compression molding step may be performed under a pressure in the range of 3 to 5 MPa.

[0021] According to another example, the firing step may include a step of heat-treating the compression-molded multilayer laminate at a temperature higher than the melting point (Tm) of the dry film and a pressure lower than the pressure during the compression molding; a step of stabilizing the heat-treated multilayer laminate while applying pressure up to the pressure during the compression molding at a temperature lower than the melting point (Tm) of the dry film; and a step of cooling the stabilized multilayer laminate.

[0022] According to another example, before forming the second circuit pattern, the method may further include a step of forming a plurality of holes in the hot-pressed multilayer laminate; and a step of plating the plurality of holes.

[0023] According to another example, after the hole plating step, the method further includes a step of preparing an nth metal laminate including an nth metal foil and an nth dry film of a thermoplastic resin composition disposed on one surface of the nth metal foil; and the multilayer laminate forming step or the hole plating step is repeatedly performed once or a plurality of times, but the multilayer laminate is formed using the nth metal laminate instead of the metal laminate, and the MFR of each dry film can be controlled to gradually increase from the n-2th dry film to the nth dry film (wherein, n is an integer of 3 or more).

[0024] A multilayer printed circuit board according to the present invention has an MFR of a thermoplastic resin layer in an inner circuit board that is smaller than an MFR of a thermoplastic resin layer in an outer circuit board, so that interlayer adhesion between circuit boards is excellent even without including a bonding sheet.

[0025] Furthermore, the multilayer printed circuit board according to the present invention is built up by directly bonding the circuit boards using a single material without the use of a bonding sheet. Therefore, the multilayer printed circuit board according to the present invention can achieve environmental reliability and low dielectric loss in the high-frequency range. Furthermore, the multilayer printed circuit board according to the present invention can realize 3D-shaped circuits through bending and folding by slimming the product, thereby improving processability.

[0026] In addition, the multilayer printed circuit board according to the present invention has excellent low-loss characteristics in a high-frequency range because each thermoplastic resin layer contains a fluorine-based component.

[0027] In addition, since the present invention does not perform a process of cutting and bonding a bonding sheet when manufacturing a multilayer printed circuit board, unlike in the prior art, the manufacturing process can be simplified, and can also be applied to a roll-to-roll process using a belt press to manufacture a roll-shaped multilayer printed circuit board.

[0028] FIG. 1 is a cross-sectional view schematically showing a multilayer printed circuit board according to a first embodiment of the present invention.

[0029] Figure 2 is an enlarged cross-sectional view of part A of Figure 1.

[0030] Figure 3 is a cross-sectional view schematically showing a multilayer printed circuit board according to a second embodiment of the present invention.

[0031] Figures 4a to 4f are cross-sectional views schematically showing a manufacturing process of a multilayer printed circuit board according to a third embodiment of the present invention.

[0032] <Explanation of symbols>

[0033] 100A, 100B: Multilayer printed circuit board,

[0034] 110: first circuit board, 111: first thermoplastic resin layer,

[0035] 112: First circuit pattern, 113: Fiber-containing substrate,

[0036] 120: Second circuit board, 121: Second thermoplastic resin layer,

[0037] 122: Second circuit pattern, Via: via,

[0038] 130: Third circuit board, 131: Third thermoplastic resin layer,

[0039] 132: Third circuit pattern, 120a: Metal laminate,

[0040] 121a: First drying film, 122a: Metal foil,

[0041] 10: carrier film, 20: protective metal foil,

[0042] H: Hall, Via: Via

[0043] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. These embodiments of the present invention are provided to more fully explain the present invention to those skilled in the art. The following embodiments may be modified in various ways, and the scope of the present invention is not limited to the following embodiments. Throughout this specification, the same reference numerals denote the same structures.

[0044] Unless otherwise defined, all terms (including technical and scientific terms) used herein may be used in their common sense to those of ordinary skill in the art to which the present invention pertains. Furthermore, terms defined in commonly used dictionaries are not to be interpreted ideally or excessively unless explicitly and specifically defined otherwise.

[0045] Furthermore, the sizes and thicknesses of each component shown in the drawings are arbitrarily indicated for convenience of explanation, and thus the present invention is not necessarily limited to the illustrated components. In the drawings, the thicknesses are enlarged to clearly represent various layers and regions. Furthermore, in the drawings, the thicknesses of some layers and regions are exaggerated for convenience of explanation.

[0046] Additionally, throughout the specification, whenever a part is said to "include" a component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise specifically stated.

[0047] Additionally, throughout the specification, “above” or “on” means not only when located above or below the target part, but also when there is another part in between, and does not necessarily mean located above with respect to the direction of gravity.

[0048] In addition, the terms “first”, “second”, etc. in this specification are not used to indicate any order or importance, but are used to distinguish between components.

[0049]

[0050] Multilayer printed circuit board

[0051] FIG. 1 is a cross-sectional view schematically showing a multilayer printed circuit board according to a first embodiment of the present invention, FIG. 2 is an enlarged cross-sectional view of part A of FIG. 1, and FIG. 3 is a cross-sectional view schematically showing a multilayer printed circuit board according to a second embodiment of the present invention.

[0052] Referring to FIGS. 1 to 3, a multilayer printed circuit board (100A, 100B) according to the present invention does not include a bonding sheet, and includes a first circuit board (110) including a first thermoplastic resin layer (111) and a first circuit pattern (112) disposed on at least one surface 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 surface of the first circuit board (110) and a second circuit pattern (122) disposed on one surface of the second thermoplastic resin layer (121), wherein a melt flow rate (MFR) of the second thermoplastic resin layer (111) is greater than an MFR of the first thermoplastic resin layer (121). Optionally, the multilayer printed circuit board (100B) according to the present invention further includes a third circuit board (130) to an n-th circuit board (not shown) sequentially arranged on the second circuit board (120) (wherein, n is 3 or more), the third circuit board (130) includes a third thermoplastic resin layer (131) arranged on the second circuit board (120), and a third circuit pattern (132) arranged on one surface of the third thermoplastic resin layer (131), and the n-th circuit board includes an n-th thermoplastic resin layer arranged on the n-1-th circuit board, and an n-th circuit pattern arranged on one surface of the n-th thermoplastic resin layer, and the MFR of each thermoplastic resin layer gradually decreases as it goes from the second thermoplastic resin layer (121) to the n-th thermoplastic resin layer (not shown). It can grow.

[0053] Specifically, the multilayer printed circuit board (100A, 100B) of the present invention is formed by integrating a first circuit board (110); a second circuit board (120) laminated on one or both sides of the first circuit board (110); and optionally, a third circuit board (130) to an n-th circuit board (not shown) sequentially laminated on the second circuit board (120) (wherein n is 3 or more, specifically 3 to 10). At this time, the thermoplastic resin layers (111, 121, 131) of each circuit board (110, 120, 130) are directly bonded to each other without a bonding sheet. For example, as illustrated in FIG. 1, a second thermoplastic resin layer (121) of a second circuit board (120) is directly attached to both sides of a first thermoplastic resin layer (111) in a first circuit board (110). In the multilayer printed circuit board (100A, 100B) of the present invention, since both the first thermoplastic resin layer (111) and the second thermoplastic resin layer (121) contain thermoplastic components, they have the property of melting when heat is applied. Therefore, since the first thermoplastic resin layer (111) and the second thermoplastic resin layer (121) of the present invention melt during hot press processing, they can be bonded to each other without a heterogeneous interface even without a bonding sheet. Accordingly, the first thermoplastic resin layer (111) and the second thermoplastic resin layer (121) can be integrated with each other as a single material. However, the first circuit board (110) includes a circuit pattern, which is an inner circuit, and the dimensional stability of the circuit pattern may be reduced due to an increase in fluidity of the resin layer and a decrease in dimensional stability caused by the temperature and pressure applied during hot press processing, which may increase the defect rate.

[0054] Accordingly, in the present invention, the MFR of the second thermoplastic resin layer (121) is adjusted to be greater than the MFR of the first thermoplastic resin layer (111). As a result, the dimensional stability and flow stability of the first thermoplastic resin layer (111) of the present invention are higher than those of the second thermoplastic resin layer (121) at the same temperature. Therefore, in the present invention, the first circuit board (110) and the second circuit board (120) can be built up by directly attaching the first thermoplastic resin layer (111) and the second thermoplastic resin layer (121) to each other without deteriorating the dimensional stability of the first circuit pattern (112) in the first circuit board (110). At this time, unlike conventional multilayer printed circuit boards including thermosetting resin layers (e.g., epoxy resin layers), the multilayer printed circuit board (100A, 100B) according to the present invention does not need to include a bonding sheet because the thermoplastic resin layers can be directly bonded and integrated with excellent interlayer adhesive strength.

[0055] In this way, the multilayer printed circuit board (100A, 100B) according to the present invention is built up by bonding single materials without a heterogeneous interface. Therefore, the multilayer printed circuit board (100A, 100B) according to the present invention can implement environmental reliability and low dielectric loss in a high-frequency range. In addition, since the multilayer printed circuit board (100A, 100B) according to the present invention does not include a bonding sheet, it is possible to implement a 3D-shaped circuit through bending and folding by reducing the thickness, and thus, processability can be improved. In addition, when each thermoplastic resin layer of the multilayer printed circuit board (100A, 100B) according to the present invention includes a fluorine-based component, the low-loss characteristic in a high-frequency range can be improved. In addition, since the present invention does not perform cutting and welding processes of bonding sheets, unlike in the prior art, when manufacturing a multilayer printed circuit board, the manufacturing process can be simplified, and can also be applied to a roll-to-roll process using a belt press to manufacture a roll-shaped multilayer printed circuit board.

[0056] Hereinafter, a first embodiment of the present invention will be described with reference to FIG. 1.

[0057] FIG. 1 is a cross-sectional view schematically showing a multilayer printed circuit board according to a first embodiment of the present invention.

[0058] The multilayer printed circuit board (100A) of the present invention, as illustrated in FIG. 1, includes a first circuit board (110); and second circuit boards (120) arranged on both sides of the first circuit board (110). In this case, the second circuit board (120) arranged on one side of the first circuit board (110) may be omitted. In addition, the multilayer printed circuit board (100A) of the present invention may further include vias that are formed by penetrating at least one of the first thermoplastic resin layer (111) and the second thermoplastic resin layer (121), and electrically connecting between the first circuit patterns (112) and / or between the first circuit pattern (112) and the second circuit pattern (122).

[0059] (1) First circuit board

[0060] In the multilayer printed circuit board (100A) of the present invention, the first circuit board (110) includes a first thermoplastic resin layer (111) and a first circuit pattern (112) arranged on at least one surface of the first thermoplastic resin layer (111), and may be, for example, a double-sided circuit board, specifically, a double-sided flexible circuit board.

[0061] According to an example, the first circuit board (110) includes a first thermoplastic resin layer (111) and a first circuit pattern (112) respectively disposed on both sides of the first thermoplastic resin layer (111), as illustrated in FIG. 1. Optionally, the first circuit board (110) may additionally include a fiber-containing substrate (113) embedded in the first thermoplastic resin layer (111).

[0062] Below, each component of the first circuit board (110) is described.

[0063] (a) first thermoplastic resin layer

[0064] The above first thermoplastic resin layer (111) is an insulating layer, and can be directly bonded to the second thermoplastic resin layer (121) to build up circuit boards while protecting the first circuit pattern (112). It is preferable that the first thermoplastic resin layer (111) be a fully solidified insulating layer to ensure dimensional stability of the first circuit pattern (112) when laminating the second circuit board (120) on the first circuit board (110).

[0065] The melt flow rate (MFR) of the first thermoplastic resin layer (111) is smaller than the MFR of the second thermoplastic resin layer (121), as described above. In one example, the MFR of the second thermoplastic resin layer (111) may be 10 to 100 times larger than the MFR of the first thermoplastic resin layer (121). The MFR of the first thermoplastic resin layer (111) may be in the range of about 0 to 1 g / 10 min, specifically about 0.01 to 1 g / 10 min, at a temperature of 372° C. and a load of 5 kg, and the MFR of the second thermoplastic resin layer (121) may be more than 1.5 g / 10 min and less than or equal to 5 g / 10 min, at a temperature of 372° C. and a load of 5 kg. Here, the MFR (Melt Flow Rate) of each resin layer is the total amount of extruded resin measured for 10 min under the conditions of 372 ℃ and 5 kg according to the ISO 12086-2 test method.

[0066] The dielectric constant (Dk) of the first thermoplastic resin layer (111) may be about 2 to 7 at 25°C and 10 GHz, and the dielectric loss tangent (Df) may be 0.0001 to 0.002.

[0067] The first thermoplastic resin layer (111) may include a thermoplastic component commonly known in the art. For example, the first thermoplastic resin layer (111) may be formed of a first thermoplastic resin composition (C1) including a first fluororesin filler, a first inorganic filler, and a first binder resin. Optionally, the first thermoplastic resin composition (C1) may additionally include a first organic solvent.

[0068] Hereinafter, the composition of the first thermoplastic resin composition (C1) will be described.

[0069] 1) First fluorine resin filler

[0070] In the first thermoplastic resin composition (C1) according to the present invention, the first fluororesin filler is a fluororesin particle containing fluorine (F), and is a particle-shaped organic filler such as a powder in a solid state at room temperature (about 20±5°C). The first fluororesin filler maintains the particle shape when the first thermoplastic resin composition (C1) is dried, and is bound together with the first inorganic filler by the first binder resin, and is subsequently melted by high-temperature pressing and included in the first thermoplastic resin layer (111) as a polymer matrix component together with the first binder resin. Therefore, the first fluororesin filler not only implements low dielectric constant and low dielectric loss characteristics of the first thermoplastic resin layer, but also can improve heat resistance and improve adhesion between a fiber-containing substrate or a metal foil.

[0071] The first fluororesin filler usable in the present invention is not particularly limited as long as it is a particle formed of a fluorine-containing resin in the art. Non-limiting examples of the first fluororesin filler include polytetrafluoroethylene (PTFE), perfluoroalkoxy alkane (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), polychlorotrifluoroethylene (PCTFE), ethylene-tetrafluoroethylene copolymer (ETFE), tetrafluoroethylene-chlorotrifluoroethylene copolymer (TFE / CTFE), ethylene-chlorotrifluoroethylene copolymer (ECTFE), polychlorotrifluoroethylene (PCTFE), etc., and these may be used alone or in a mixture of two or more. For example, the first fluororesin filler may include two or more selected from the group consisting of PFA, PTFE, and FEP.

[0072] The melt flow rate (MFR) of the first fluororesin filler may 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 may be 0 to 0.1 g / 10 min (specifically, about 0.01 to 1 g / 10 min), the MFR of PFA may be about 0.1 to 20 g / 10 min, and the MFR of FEP may be about 1 to 40 g / min. As such, the MFR of the first fluororesin filler may 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. At this time, the MFR of the first fluororesin filler is preferably smaller than the MFR of the second fluororesin filler of the second thermoplastic resin composition. Accordingly, the first thermoplastic resin layer (111) has superior dimensional stability and flow stability compared to the second thermoplastic resin layer (121) at the same temperature, thereby improving the dimensional stability of the first circuit pattern (112). Here, the MFR (Melt Flow Rate) of the first fluororesin is measured by measuring the total amount of extruded resin for 10 minutes under the conditions of 372°C and 5 kg according to the ISO 12086-2 test method. If the first fluororesin is a mixture of two or more types, the MFR of the mixture is measured.

[0073] In the present invention, the first fluororesin filler includes two or more types of fluororesin fillers having different MFRs, and by controlling the mixing ratio thereof, the MFR of the first thermoplastic resin layer (111) can be controlled within a range of about 0 to 0.1 g / 10 min, specifically, about 0.01 to 1 g / 10 min. For example, the first fluororesin filler may include a 1A fluororesin filler having an MFR of about 0.01 to 10 g / 10 min at a temperature of 372° C. and a load of 5 kg; and a 1B fluororesin filler having an MFR of about 0.1 to 40 g / 10 min. At this time, the content of the 1A fluororesin filler may be greater than the content of the 1B fluororesin filler.

[0074] For example, the first fluororesin filler includes at least one selected from the group consisting of (a) PTFE and (b) PFA and FEP, wherein the content of the PTFE may be greater than the content of the PFA and / or FEP. The usage ratio of the PTFE and the PFA and / or FEP (PTFE: PFA and / or FEP) may be a weight ratio of 2:1 to 10:1. In addition, when PTFE is used together with PFA and FEP as the first fluororesin filler, the content of the PFA may be adjusted to be greater than the content of the FEP so that the MFR of the first thermoplastic resin layer (111) becomes smaller 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.

[0075] As another example, the first fluororesin filler includes (a) PTFE; and (b) PFA, wherein the content of PTFE may be greater than the content of PFA. The usage ratio of PTFE and PFA (PTFE:PFA) may be 2:1 to 10:1 by weight.

[0076] As another example, the first fluororesin filler may include a fluororesin filler with a low MFR, such as PTFE. In this case, the second fluororesin may include a fluororesin filler with a higher MFR than PTFE, such as PFA, PTFE, or both. Furthermore, the second fluororesin may additionally include PTFE, in which case the content of PTFE in the second fluororesin is lower than the content of PTFE in the first fluororesin filler.

[0077] Also, the average particle diameter (D) of the first fluorine resin filler 50 ) may be in the range of about 5 to 30 ㎛. If the first fluororesin filler has the above-mentioned average particle diameter, the first fluororesin filler can be uniformly dispersed without agglomeration in the first thermoplastic resin composition (C1), and the handling property of the first thermoplastic resin composition (C1) after coating can be improved. At this time, in the present invention, one type of fluororesin filler having the same average particle diameter can be used alone as the first fluororesin filler, or two or more types of fluororesin fillers having different average particle diameters can be mixed and used. Here, the average particle diameter (D) of the first fluororesin filler 50 ) can be measured according to the ASTM D4464-10 test method.

[0078] According to an example, the first fluorine resin filler has an average particle diameter (D) of 20 to 30 μm 50 ) having a first A fluorine resin filler; and an average particle diameter (D) of 5 to 10 μm 50 ) may include a 1B fluorine resin.

[0079] In addition, the first fluororesin filler can have a relative permittivity (Dk) of about 2.0 to 2.1 and a dielectric loss tangent (Df) of 0.0001 to 0.002 at 25°C and 10 GHz. In this way, since the first fluororesin filler has low dielectric properties, the low permittivity and low dielectric loss properties of the first thermoplastic resin layer (111) can be implemented. Here, the relative permittivity (Dk) and the dielectric loss tangent (Df) of the first fluororesin filler are measured under the conditions of 25°C and 10 GHz according to the split post dielectric resonator (SPDR) method (IEC 61189-2-721 test method).

[0080] In addition, the shape of the first fluororesin filler is not particularly limited, and includes, for example, spherical, flake, dendrite, conical, pyramidal, and amorphous shapes, and these may be used alone or in combination of two or more. In one example, the shape of the first fluororesin filler may be spherical. In this case, since the surface area of ​​the first fluororesin filler is minimized, the processing characteristics of the first thermoplastic resin composition can be improved, and isotropic characteristics can be imparted to the first thermoplastic resin layer.

[0081] In the first thermoplastic resin composition (C1) of the present invention, the content of the first fluororesin filler may be in the range of about 50 to 80 wt% based on the total weight of the resin composition. By adjusting the content of the first fluororesin filler within the above-described range, the resin composition can form a resin layer having a low dielectric constant.

[0082] For example, when the first fluororesin filler includes PTFE and PFA in a weight ratio of 10:1, and the content of the first fluororesin filler is adjusted to about 50 wt%, the content of the first inorganic filler is adjusted to about 45 wt%, and the content of the first binder resin is adjusted to about 5 wt%, the MFR of the first thermoplastic resin layer may be 0 g / 10 min.

[0083] As another example, when the first fluororesin filler includes PTFE and PFA in a weight ratio of 2:1, and the content of the first fluororesin filler is adjusted to about 80 wt%, the content of the first inorganic filler is adjusted to about 17 wt%, and the content of the first binder resin is adjusted to about 3 wt%, the MFR of the first thermoplastic resin layer may be about 1 g / 10 min.

[0084] 2) 1st weapon filler

[0085] In the first thermoplastic resin composition (C1) according to the present invention, the first inorganic filler can reduce 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 bending characteristics, low expansion, mechanical strength (toughness), and low stress of the first circuit board (110). In addition, the dielectric characteristics of the first thermoplastic resin layer (111) can be controlled depending on the components and / or content of the first inorganic filler.

[0086] Non-limiting examples of the first inorganic filler usable in the present invention include silica such as natural silica, fused silica, amorphous silica, crystalline silica, etc.; boehmite, alumina, talc, glass (e.g., spherical glass), calcium carbonate, magnesium carbonate, magnesia, clay, calcium silicate, titanium oxide, antimony oxide, glass fiber, aluminum borate, barium titanate, strontium titanate, calcium titanate, magnesium titanate, bismuth titanate, titania (e.g., TiO2), barium zirconate, calcium zirconate, boron nitride, silicon nitride, talc, mica, etc. These first inorganic fillers may be used alone or in combination of two or more. Among these, since silica, alumina, and titania have low dielectric constants, they can lower the permittivity and dielectric loss tangent of the resin layer while reducing the difference in thermal expansion coefficient between the resin layer and the metal foil.

[0087] In one example, the first inorganic filler may include at least one selected from the group consisting of silica (e.g., SiO2), alumina (e.g., Al2O3), and titania (e.g., TiO2). In another example, the first inorganic filler may be titania (e.g., TiO2); and silica (e.g., SiO2). In this case, titania may be included in a larger amount than silica. For example, the content of titania may be about 20 to 30 wt% based on the total amount of the resin composition.

[0088] The size (e.g., average particle diameter, maximum particle diameter), shape and content of these first inorganic fillers are important parameters that affect the properties of the first thermoplastic resin layer.

[0089] Specifically, the average particle diameter (D) of the first weapon filler 50) may be in the range of about 0.1 to 30 μm. This is advantageous in the dispersibility of the first inorganic filler. At this time, the first inorganic filler may include two or more types of inorganic fillers having different maximum particle sizes.

[0090] According to an example, the first inorganic filler has an average particle diameter (D) of about 0.1 to 10 μm. 50 ) having a first A inorganic filler; and an average particle diameter (D) of more than about 10 μm and less than or equal to 30 μm 50 ) may include a first B inorganic filler. At this time, the first A inorganic filler may include two or more types of inorganic fillers having different components, and the first B inorganic filler may also include two or more types of inorganic fillers having different components. For example, the first inorganic filler may have an average particle diameter (D) of 0.1 to 10 ㎛. 50 ) having a first A inorganic filler; and an average particle diameter (D) of greater than about 10 μm to 30 μm 50 ) may include a first B inorganic filler, wherein the first A inorganic filler may include silica and titania, and the first B inorganic filler may include silica and titania. Here, the average particle diameter (D) of the first inorganic filler 50 ) can be measured according to ASTM D4464-10.

[0091] In addition, the shape of the first weapon filler is not particularly limited, and includes, for example, a sphere, a flake, a dendrite, a cone, a pyramid, an amorphous shape, etc.

[0092] Additionally, the first inorganic filler may be surface-treated with a surface treatment agent. The surface treatment agent is not particularly limited as long as it is generally known in the art, and examples thereof include a silane coupling agent. In this case, the content of the silane coupling agent may be about 0.1 to 20 parts by weight, specifically about 0.1 to 10 parts by weight, based on 100 parts by weight of the first inorganic filler.

[0093] The silane coupling agent usable in the present invention is not particularly limited as long as it is one commonly known in the art, and examples thereof include vinyl-based, epoxy-based, methacryloxy-based, amino-based, mercapto-sulfide-based, and ureide-based silane coupling agents, and may 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 during solidification of the resin composition.

[0094] The aforementioned silane coupling agent not only serves to surface-treat the first inorganic filler, but may also be additionally 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 improving the low-dielectric properties of the first thermoplastic resin layer.

[0095] The content of such silane coupling agent may be about 0.0001 to 10 wt%, specifically about 0.01 to 5 wt%, and more specifically about 0.1 to 3 wt%, based on the total amount of the resin composition.

[0096] In the resin composition of the present invention, the content of the first inorganic filler may be in the range of about 20 to 50 wt%, specifically about 30 to 45 wt%, based on the total weight of the resin composition. If the content of the first inorganic filler is less than about 20 wt%, the mechanical strength increasing effect may be insufficient, making process application difficult. On the other hand, if the content of the first inorganic filler exceeds about 50 wt%, the moldability of the resin composition may deteriorate.

[0097] 3) First binder resin

[0098] In the first thermoplastic resin composition (C1) of the present invention, the first binder resin is a binder resin having excellent high-temperature heat resistance, and can bind the first fluororesin filler and the first inorganic filler when forming the first thermoplastic resin layer. In addition, the first binder resin has excellent adhesion (adhesion) to a metal foil, and thus can improve the adhesive properties between the dried product of the first thermoplastic resin composition (C1) and the metal foil.

[0099] Such first binder resin may have a thermal decomposition temperature (Td) of about 400°C or higher, specifically in the range of about 400 to 450°C.

[0100] In addition, the first binder resin may have a dielectric constant (Df) of about 0.0001 to 0.002 at 10 GHz and a dielectric constant (Dk) of about 2.0 to 3.0 at 10 Hz. In this case, the low-k dielectric properties of the first thermoplastic resin layer (111) can be improved. Here, the dielectric constant (Dk) and dielectric constant (Df) of the first binder resin are measured under conditions of 25°C and 10 GHz according to the split post dielectric resonator (SPDR) method (IEC 61189-2-721 test method).

[0101] In addition, the viscosity (at about 25°C) of a solution in which 5 wt% of the first binder resin is dissolved in an organic solvent (e.g., toluene) may be about 50 to 100 cPs. In this case, the viscosity of the first thermoplastic resin composition (C1) of the present invention may be adjusted to be within a range of about 150 to 500 cPs, so that processability may be improved when manufacturing a roll-type first circuit board. Here, the viscosity of the first binder resin and the resin composition are each measured using a viscosity measurement method known in the art, such as the Blook field method (rotation speed: about 20 rpm).

[0102] In one example, the first binder resin may be a fluorinated elastomer.

[0103] The above fluorine-based elastomer is a thermoplastic elastomer containing at least one fluorine (F) atom in at least one repeating unit, and unlike the first fluorine resin filler, is soluble in an organic solvent. This fluorine-based elastomer has a high thermal decomposition temperature (Td) of 400°C or higher, and a low dielectric constant (Df) and dielectric constant (Dk).

[0104] Fluorine-based elastomers usable in the present invention include fluoroelastomers (FKM), specifically copolymers containing two or more of vinylidene fluoride (VDF), hexafluoropropylene (HFP), and tetrafluoroethylene (TFE). Depending on the number of monomers, they may be binary or ternary copolymers, and examples thereof include, but are not limited to, VDF-HFP copolymers and VDF-HFP-TFE copolymers. These may be used alone, or two or more may be mixed and used.

[0105] The content of fluorine (F) in the fluorine-based elastomer is not particularly limited, but when it is within the range of about 65 to 80 wt% per molecule of the fluorine-based elastomer, excellent low-dielectric properties and low-dielectric loss properties can be imparted to the first thermoplastic resin layer (111).

[0106] In the first thermoplastic resin composition (C1), the content of the first binder resin may be in a range of about 1 to 10 wt%, specifically about 1 to 7 wt%, and more specifically about 1 to 5 wt%, based on the total amount (100 wt%) of the first thermoplastic resin composition (excluding the organic solvent and additives). If the content of the first binder resin is less than about 1 wt%, the effect of binding the fillers may be reduced, and on the other hand, if the content of the first binder resin exceeds 10 wt%, not only the adhesion with the fiber-containing substrate (113) but also the adhesion with a metal foil (e.g., copper foil) may be reduced, and thus the metal foil (circuit pattern) may be peeled off when manufacturing and using a roll-type first circuit board.

[0107] 4) First organic solvent

[0108] The first thermoplastic resin composition (C1) of the present invention may additionally include a first organic solvent.

[0109] The first organic solvent usable in the present invention is not particularly limited as long as it can dissolve the first binder resin. Examples of such first organic solvents include, but are not limited to, 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 amyl ketone, cyclohexanone, isophorone, and N-methylpyrrolidone; and ester compounds such as ethyl acetate, butyl acetate, and methyl cellosolve acetate. These may be used alone, or two or more may be mixed and used.

[0110] The content of the first organic solvent may be used as a content known in the art, and may be a residual amount adjusted so that the total amount of the first thermoplastic resin composition (C1) becomes 100 wt%. For example, it may be in the range of about 40 to 70 parts by weight, specifically in the range of about 45 to 65 parts by weight, based on 100 parts by weight of the first thermoplastic resin composition (C1) (excluding the first organic solvent and the first additive).

[0111] 5) First additive

[0112] Meanwhile, the first thermoplastic resin composition (C1) of the present invention may further include, in addition to the first fluororesin filler, the first inorganic filler, the first binder resin, and the first organic solvent described above, a first additive such as a flame retardant, another thermosetting resin or thermoplastic resin, an ultraviolet absorber, an antioxidant, a polymerization initiator, a dye, a pigment, a dispersant, a thickener, a leveling agent, a colorant, etc. known in the art, as needed, within a range that does not impair the physical properties of the composition.

[0113] The content of the first additive can be used as known in the art, and may be, for example, about 0.0001 to 10 wt% based on the total amount of the first thermoplastic resin composition (C1).

[0114] The viscosity of the first thermoplastic resin composition (C1) according to the present invention can be adjusted depending on the types and contents of the first fluororesin filler, the first inorganic filler, the first binder resin, and the first organic solvent in the composition, and can be, for example, about 200 to 1000 cPs. In one example, when the first thermoplastic resin composition (C1) has the viscosity described above, the first thermoplastic resin layer (111) can be directly formed on the metal foil by directly applying the first thermoplastic resin composition (C1) on the metal foil using a roll-to-roll coating method and drying the result.

[0115] (b) First circuit pattern

[0116] In the first circuit board (110) according to the present invention, the first circuit pattern (112) is arranged on both sides of the first thermoplastic resin layer (111) described above, and is patterned in a predetermined shape with a predetermined width and thickness. This first circuit pattern (112) can perform various functions depending on the design of the corresponding layer, and can be, for example, a power supply line, a ground line, a ground electrode, etc. In this way, some of the first circuit patterns (112) arranged on each side of the first thermoplastic resin layer (111) can be electrically connected to each other, or can be electrically connected to a circuit pattern in another board [e.g., a second circuit pattern (122), etc.] through a via.

[0117] The material forming 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 conductive material 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., and these may be used alone or in the form of a mixture or alloy of two or more. In one example, the material of the first circuit pattern (112) may be copper (Cu).

[0118] (c) fiber-containing substrate

[0119] The first circuit board (110) according to the present invention may additionally include a fiber-containing substrate (113).

[0120] For example, as illustrated in FIG. 2, a fiber-containing substrate (113) embedded in the first thermoplastic resin layer (111) may be additionally included.

[0121] As another example, although not shown, a fiber-containing substrate (113) may additionally be included between the first thermoplastic resin layers (111).

[0122] The fiber-containing substrate (113) is a portion that supports the first circuit board (110), and since it contains fibers, it can improve the low dielectric constant and low loss characteristics of the first circuit board (110). In addition, the fiber-containing substrate (113) can be in close contact with the dried product of the first thermoplastic resin during the manufacture of the first circuit board, thereby exhibiting excellent flexibility, heat resistance, and adhesiveness.

[0123] For example, the fiber-containing substrate (113) may be a fiber aggregate.

[0124] As another example, the fiber-containing substrate (113) may be a prepreg comprising a fiber assembly; and a semi-cured resin impregnated into the fiber assembly and having a thermal decomposition temperature of 450°C or higher. Here, the semi-cured resin is a resin in a B-stage state that is semi-cured by impregnating a high heat-resistant resin composition having a thermal decomposition temperature of 450°C or higher into the fiber assembly and then heating it.

[0125] The above fiber aggregate may be a plurality of fibers, or a fiber-containing substrate made of fibers such as yarn, woven fabric, non-woven fabric, knitting, braid, etc.

[0126] Non-limiting examples of the above fibers include vegetable fibers such as cotton and hemp; animal fibers such as wool and silk; regenerated fibers such as rayon; synthetic fibers such as polyester, acrylic, nylon, polyurethane, etc.; inorganic fibers such as glass fiber and carbon fiber; and metal fibers, which may be used alone or in combination of two or more. Among these, inorganic fibers such as glass fiber and carbon fiber have low moisture content, so pores are not formed in the fiber-containing substrate (113) during hot pressing later, and they also have excellent thermal stability.

[0127] Examples of the above fiber assembly include, but are not limited to, a plurality of glass fibers (e.g., E-glass, D-glass, S-glass, NE-glass, T-glass, and Q-glass, etc.), glass paper, glass roving, glass yarn, glass woven fabric, glass chopped strands, glass chopped strands mat, glass roving cloth, glass surfacing mat, etc.

[0128] The semi-cured resin usable in the present invention is a cured product obtained by semi-curing (B-stage) a high heat-resistant resin composition having a thermal decomposition temperature of 400°C or higher. The high heat-resistant resin composition usable in the present invention is not particularly limited as long as it is one commonly used in prepregs in the art and has a thermal decomposition temperature of 400°C or higher.

[0129] According to an example, the high heat resistance resin composition may include at least one high heat resistance resin selected from the group consisting of epoxy resins and fluororesins, and may optionally further include a curing agent.

[0130] In the above-described high heat-resistant resin composition, the epoxy resin is a thermosetting resin, and by forming a three-dimensional network structure after curing, it can improve the adhesive strength between the prepreg (113) and the first thermoplastic resin layer (111), and also has excellent heat resistance, water resistance, and moisture resistance, thereby improving the heat-resistant reliability of the first circuit board. In addition, the epoxy resin not only has excellent mechanical strength, electrical insulation, chemical resistance, dimensional stability, and moldability, but also has excellent compatibility with other resins.

[0131] The epoxy resin usable in the present invention is a polymer containing at least one epoxide group in the molecule, and is preferably an epoxy resin that does not contain a halogen atom such as bromine in the molecule. In addition, the epoxy resin may contain silicone, urethane, polyimide, polyamide, etc. in the molecule, and may also contain phosphorus atoms, sulfur atoms, nitrogen atoms, etc. in the molecule.

[0132] Non-limiting examples of such epoxy resins include bisphenol A type epoxy resin, bisphenol F type epoxy resin, or hydrogenated versions thereof, glycidyl ether epoxy resins such as phenol novolac type epoxy resin, cresol novolac type epoxy resin, glycidyl ester epoxy resins such as hexahydrophthalic acid glycidyl ester, dimer acid glycidyl ester, glycidylamine epoxy resins such as triglycidyl isocyanurate, tetraglycidyldiamino diphenylmethane, linear aliphatic epoxy resins such as epoxidized polybutadiene, and epoxidized soybean oil, etc. These may be used alone or in combination of two or more.

[0133] In the above-described high heat-resistant resin composition, the fluoropolymer is a thermoplastic resin with excellent chemical stability and high-temperature heat stability, and is a type of heat-resistant resin with a high melting point (Tm) of about 260 ℃ or higher, and is preferably in a liquid state. Examples of such fluoropolymers include, but are not limited to, polytetrafluoroethylene resin (PTFE), perfluoroalkoxy alkane (PFA), tetrafluoroethylene-hexafluoropropylene copolymer resin (FEP), polychlorotrifluoroethylene resin (PCTFE), ethylene-tetrafluoroethylene copolymer resin (ETFE), ethylene-chlorotrifluoroethylene copolymer resin (ECTFE), tetrafluoroethylene-chlorotrifluoroethylene copolymer (TFE / CTFE), polyvinylidene fluoride resin (PVDF), polyvinyl fluoride resin (PVF), tetrafluoroethylene-perfluoroalkyl vinyl ether-hexafluoropropylene copolymer resin, and the like.

[0134] In the above high heat-resistant resin composition, the curing agent is a component that cures the epoxy resin, and is not particularly limited as long as it is known in the art to cure the epoxy resin, and examples thereof include an acid anhydride-based curing agent, an amine-based curing agent, a phenol-based curing agent, and the like.

[0135] Specifically, examples of the curing agent include acid anhydride curing agents such as tetrahydrophthalic anhydride, methyl tetrahydrophthalic anhydride, methyl hexahydrophthalic anhydride, hexahydrophthalic anhydride, trialkyl tetrahydrophthalic anhydride, methyl cyclohexenedicarboxylic anhydride, phthalic anhydride, maleic anhydride, and pyromellitic anhydride; aromatic amine curing agents such as metaphenylenediamine, diaminodiphenylmethane, and diaminodiphenylsulfone; aliphatic amine curing agents such as diethylenetriamine and triethylenetetramine; Phenolic curing agents such as phenol aralkyl type phenol resin, phenol novolac type phenol resin, xyloc type phenol resin, cresol novolac type phenol resin, naphthol type phenol resin, terpene type phenol resin, multifunctional type phenol resin, dicyclopentadiene type phenol resin, naphthalene type phenol resin, novolac type phenol resin synthesized from bisphenol A and resol; latent curing agents such as dicyandiamide, etc., are not limited thereto. These may be used alone or in a mixture of two or more.

[0136] The content of such a hardener is not particularly limited, and may be, for example, about 1 to 10 parts by weight, specifically about 1 to 6 parts by weight, based on 100 parts by weight of a high heat-resistant resin (e.g., epoxy resin).

[0137] The thickness of the aforementioned fiber-containing substrate (113) is not particularly limited and may be, for example, about 10 to 200 μm. However, when the thickness of the fiber-containing substrate (113) is in the range of about 30 to 70% of the thickness of the flexible metal laminate, the thermal and mechanical properties of the first circuit board can be further improved.

[0138] (2) Second circuit board

[0139] In the multilayer printed circuit board (100A) of the present invention, the second circuit board (120) is arranged on at least one surface of the first circuit board (110) described above, and is directly attached to the first thermoplastic resin layer (111) of the first circuit board (111).

[0140] According to an example, the second circuit board (120) can be placed on each of the two sides of the first circuit board (110), as shown in FIG. 1.

[0141] This second circuit board (120) includes a second thermoplastic resin layer (121) and a second circuit pattern (122) arranged on one surface of the second thermoplastic resin layer (121).

[0142] Below, each component of the second circuit board (120) is described.

[0143] (a) Second thermoplastic resin layer

[0144] The second thermoplastic resin layer (121) is an insulating layer, and is directly bonded to the first thermoplastic resin layer (111) to build up the second circuit board (120) on the first circuit board (110) while protecting the first circuit pattern (112). The second thermoplastic resin layer (121) may be solidified, but when the second circuit board (120) is laminated on the first circuit board (110), it may be in a non-solidified state, and the resin composition forming the second thermoplastic resin layer (121) may be in a dried state. At this time, the dried product of the resin composition may be a layer having a sponge structure with numerous pores present therein.

[0145] However, in the present invention, as described above, in order to directly attach the second thermoplastic resin layer (121) to the first thermoplastic resin layer (111) without a bonding sheet, the MFR of the first thermoplastic resin layer (111) is smaller than the MFR of the second thermoplastic resin layer (121).

[0146] The second thermoplastic resin layer (121) may include a thermoplastic component commonly known in the art. For example, the second thermoplastic resin layer (121) may be formed of a second thermoplastic resin composition (C2) including a second fluororesin filler, a second inorganic filler, and a second binder resin. Optionally, the second thermoplastic resin composition (C2) may additionally include a second organic solvent.

[0147] The above second fluororesin filler, like the first fluororesin filler, is a particle-type organic filler such as powder in a solid state at room temperature (about 20±5°C). This second fluororesin filler maintains its particle form when the second thermoplastic resin composition (C2) is dried, and is bound together with the second inorganic filler by the second binder resin, and is subsequently melted by high-temperature pressing and included in the second thermoplastic resin layer (121) as a polymer matrix component together with the second binder resin. Therefore, the second fluororesin filler can not only implement low dielectric constant and low dielectric loss characteristics of the second thermoplastic resin layer, but also improve heat resistance.

[0148] Examples of the second fluorine resin filler usable in the present invention are omitted because they are the same as those described in the first fluorine resin filler section.

[0149] The second fluororesin filler may have the same or different components as the first fluororesin filler. However, in the present invention, in order to directly attach the first circuit board (110) and the second circuit board (120) without a bonding sheet, it is preferable that the MFR of the second fluororesin filler is greater than the MFR of the first fluororesin filler.

[0150] For example, the MFR of the second fluororesin filler may be in the range of 2 to 20 times that of the first fluororesin filler.

[0151] As another example, the MFR of the second fluororesin filler is in the range of 0.01 to 40 g / 10 min under a temperature of 372°C and a load of 5 kg, but is greater than the MFR of the first fluororesin filler. Here, the MFR (Melt Flow Rate) of the second fluororesin is measured as the total amount of extruded resin for 10 min under the conditions of 372°C and 5 kg according to the ISO 12086-2 test method. If the second fluororesin is a mixture of two or more types, the MFR of the mixture is measured.

[0152] The second fluororesin filler may include two or more types of fluororesin fillers having different MFRs. For example, the second fluororesin filler may include a second A fluororesin (e.g., PTFE, etc.) having an MFR of about 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 about 1 to 5 g / 10 min. In this case, the content of the second A fluororesin filler may be the same as the content of the second B fluororesin filler or less than twice the content of the second B fluororesin filler.

[0153] For example, the second fluororesin filler may include PFA and PTFE. In this case, the weight ratio of PFA and PTFE (PFA:PTFE) may be 20:80 to 80:20, but is not limited thereto.

[0154] As another example, the second fluororesin filler may include at least one selected from the group consisting of (a) PTFE and; (b) PFA and FEP. At this time, the usage ratio of PTFE and PFA and / or FEP (PTFE: PFA and / or FEP) may be 1:1 to less than 2:1 by weight. In addition, when PTFE is used together with PFA and FEP as the second fluororesin filler, the content of PFA may 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.

[0155] As another example, the first fluororesin filler comprises (a) PTFE; and (b) PFA, wherein the PTFE content may be greater than the PFA content. The PTFE:PFA usage ratio may be 1:1 to less than 2:1 by weight.

[0156] Also, the average particle diameter (D) of the second fluorine resin filler 50 ) may be in the range of about 5 to 30 ㎛. If the second fluororesin filler has the above-mentioned average particle diameter, the second fluororesin filler can be uniformly dispersed without agglomeration in the second thermoplastic resin composition (C2), and the handling property of the second thermoplastic resin composition (C2) after coating can be improved. At this time, in the present invention, one type of fluororesin filler having the same average particle diameter can be used alone as the second fluororesin filler, or two or more types of fluororesin fillers having different average particle diameters can be used in combination. Here, the average particle diameter (D) of the second fluororesin filler 50 ) can be measured according to the ASTM D4464-10 test method.

[0157] According to an example, the second fluororesin filler has an average particle diameter (D) of 20 to 30 μm.50 ) having a second A fluorine resin filler; and an average particle diameter (D) of 5 to 10 μm 50 ) may include a second-B fluorine resin.

[0158] In addition, the second fluororesin filler can have a dielectric constant (Dk) of about 2.0 to 2.1 and a dielectric loss tangent (Df) of 0.0001 to 0.002 at 25°C and 10 GHz. In this way, since the second fluororesin filler has low dielectric properties, the low dielectric constant and low dielectric loss properties of the second thermoplastic resin layer (111) can be implemented. Here, the dielectric constant (Dk) and the dielectric loss tangent (Df) of the second fluororesin filler are measured under the conditions of 25°C and 10 GHz according to the split post dielectric resonator (SPDR) method (IEC 61189-2-721 test method).

[0159] In addition, the shape of the second fluororesin filler is not particularly limited, and includes, for example, spherical, flake, dendrite, conical, pyramidal, and amorphous shapes, and these may be used alone or in combination of two or more. In one example, the shape of the second fluororesin filler may be spherical. In this case, since the surface area of ​​the second fluororesin filler is minimized, the processing characteristics of the second thermoplastic resin composition can be improved, and isotropic characteristics can be imparted to the second thermoplastic resin layer.

[0160] In the second thermoplastic resin composition (C2) of the present invention, the content of the second fluororesin filler may be in the range of about 50 to 80 wt% based on the total weight of the resin composition. By adjusting the content of the second fluororesin filler within the above-described range, the resin composition can form a resin layer having a low dielectric constant.

[0161] For example, when the second fluororesin filler includes PTFE and PFA in a weight ratio of 2:1, and the content of the second fluororesin filler is adjusted to about 50 wt%, the content of the second inorganic filler is adjusted to about 45 wt%, and the content of the second binder resin is adjusted to about 5 wt%, the MFR of the second thermoplastic resin layer may be 5 g / 10 min.

[0162] As another example, when the second fluororesin filler includes PTFE and PFA in a weight ratio of 1:1, and the content of the second fluororesin filler is adjusted to about 80 wt%, the content of the second inorganic filler is adjusted to about 17 wt%, and the content of the second binder resin is adjusted to about 3 wt%, the MFR of the second thermoplastic resin layer may be less than about 1 g / 10 min.

[0163] In the second thermoplastic resin composition (C2) according to the present invention, the second inorganic filler can reduce the difference in coefficient of thermal expansion (CTE) between the second thermoplastic resin layer (121) and another layer [e.g., the second circuit pattern (122)], thereby improving the bending characteristics, low expansion, mechanical strength (toughness), and low stress of the second circuit board (120).

[0164] The above second inorganic filler may be identical to or different from the first inorganic filler in at least one of the components, size (e.g., maximum particle diameter, average particle diameter), and shape. The description of this second inorganic filler is omitted as it is the same as that described in the first inorganic filler section.

[0165] In the second thermoplastic resin composition (C2) of the present invention, the content of the second inorganic filler may be in the range of about 20 to 50 wt%, specifically about 30 to 45 wt%, based on the total amount of the resin composition. If the content of the second inorganic filler is less than about 20 wt%, the effect of reducing the dielectric constant may be insignificant, and on the other hand, if the content of the second inorganic filler exceeds about 50 wt%, the moldability of the resin composition may deteriorate.

[0166] According to an example, when the first fluororesin filler of the first thermoplastic resin composition and the second fluororesin filler of the second thermoplastic resin composition have the same components and contents, 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 thermoplastic resin layer (121) can be adjusted to be greater than the MFR of the first thermoplastic resin layer (111). Therefore, the present invention can directly attach the first circuit board (110) and the second circuit board (120) without a bonding sheet.

[0167] (b) Second circuit pattern

[0168] In the second circuit board (120) according to the present invention, the second circuit pattern (122) is arranged on one surface of the second thermoplastic resin layer (121) described above, and is patterned in a predetermined shape with a predetermined width and thickness. This second circuit pattern (122) can perform various functions depending on the design of the corresponding layer, and can be, for example, a power supply line, a ground line, a ground electrode, etc. In this way, some of the second circuit patterns (122) arranged on one surface of the second thermoplastic resin layer (121) can be electrically connected to each other, or can be electrically connected to a circuit pattern in another substrate [e.g., the first circuit pattern (112)] through a via.

[0169] A description of the material forming the second circuit pattern (122) is omitted because it is the same as that described in the first circuit pattern (112). According to an example, the material of the second circuit pattern (122) may be copper (Cu).

[0170] Hereinafter, with reference to FIG. 3, a multilayer printed circuit board (100B) according to a second embodiment of the present invention will be described.

[0171] A multilayer printed circuit board (100B) according to a second embodiment of the present invention includes a first circuit board (110); second circuit boards (120) arranged on both sides of the first circuit board (110); and third to n-th circuit boards arranged sequentially on the second circuit board (120) (wherein n is an integer greater than or equal to 3, and specifically an integer from 3 to 10).

[0172] For example, as illustrated in FIG. 3, a multilayer printed circuit board (100B) according to a second embodiment of the present invention may include a first circuit board (110); a second circuit board (120) disposed on each of both sides of the first circuit board (110); and a third circuit board disposed on the second circuit board (120).

[0173] 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 surface of the third thermoplastic resin layer, and the n-th circuit board includes an n-th thermoplastic resin layer disposed on the n-1-th circuit board, and an n-th circuit pattern disposed on one surface of the n-th thermoplastic resin layer, and the MFR of each thermoplastic resin layer gradually increases as it goes from the second thermoplastic resin layer to the n-th thermoplastic resin layer. However, the second circuit board (120), the third circuit board (130) to the n-th circuit board sequentially disposed on one surface of both surfaces of the first circuit board (110) may be omitted.

[0174] In addition, the multilayer printed circuit board (100B) of the present invention may further include a via that is formed by penetrating at least one of the first thermoplastic resin layer (111), the second thermoplastic resin layer (121), the third thermoplastic resin layer, …, the n-th thermoplastic resin layer, and electrically connects between the first circuit patterns (112), between at least one of the first circuit pattern (112), the second circuit pattern (122), the third circuit pattern (132), …, the n-th circuit pattern (here, n is an integer of 3 or more, specifically, an integer of 3 to 10).

[0175] Hereinafter, each configuration of a multilayer printed circuit board (100B) according to a second embodiment of the present invention will be described. However, since the description of the first circuit board (110) and the second circuit board (120) is the same as that described in the first embodiment, a detailed description thereof will be omitted.

[0176] The third circuit board (130) to the n-th circuit board are sequentially arranged on the second circuit board (120) and are directly attached to the n-1 thermoplastic resin layer of the n-1-th circuit board (wherein n is an integer greater than or equal to 3, specifically an integer from 3 to 10). As illustrated in Fig. 3, the third circuit board (130) is arranged on the second circuit board (120) and is directly attached to the second thermoplastic resin layer (121).

[0177] The third circuit board (130) includes a third thermoplastic resin layer (131) disposed on the second circuit board (120); and a third circuit pattern (132) disposed on one surface of the third thermoplastic resin layer (131), and the n-th circuit board includes an n-th thermoplastic resin layer disposed on the n-1-th circuit board; and an n-th circuit pattern disposed on one surface of the n-th thermoplastic resin layer (wherein, n is an integer of 3 or more, specifically, an integer of 3 to 10).

[0178] The third thermoplastic resin layer (131) to the n-th thermoplastic resin layer are each thermoplastic resin layers, and are directly bonded to the n-1-th thermoplastic resin layer to build up the n-th circuit board on the n-1-th circuit board while protecting the n-1-th circuit pattern. For example, as the third thermoplastic resin layer (131) is directly bonded to the second thermoplastic resin layer (121), the third circuit board (130) is built up on the second circuit board (120), and the third thermoplastic resin layer (131) can protect the second circuit pattern (122).

[0179] The third thermoplastic resin layer (131) to the n-th thermoplastic resin layer are in a solidified state, similar to the second thermoplastic resin layer (121), but when the n-th circuit board is laminated on the n-1-th circuit board, the resin composition forming the n-th thermoplastic resin layer may be in a dried state.

[0180] However, in the present invention, in order to directly attach the n-th thermoplastic resin layer to the n-1-th thermoplastic resin layer without a bonding sheet, the MFR of each thermoplastic resin layer gradually increases from the second thermoplastic resin layer toward the n-th thermoplastic resin layer (wherein, n is an integer greater than or equal to 3, 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 thermoplastic resin layer (131) is greater than the MFR of the second thermoplastic resin layer (121).

[0181] According to an example, as one moves from the second thermoplastic resin layer (121) toward the nth thermoplastic resin layer, the MFR of each thermoplastic resin layer may increase by 2 to 10 times. For example, as one moves from the first thermoplastic resin layer (111) toward the third thermoplastic resin layer, the MFR of the second thermoplastic resin layer (121) may increase by 2 to 10 times the MFR of the first thermoplastic resin layer (111), and the MFR of the third thermoplastic resin layer (131) may increase by 2 to 10 times the MFR of the second thermoplastic resin layer (121).

[0182] For example, the MFR of the first thermoplastic resin layer (111) may 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) may be in the range of more 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 thermoplastic resin layer (131) may be in the range of 5 to 50 g / 10 min, specifically 20 to 30 g / 10 min, at a temperature of 372° C. and a load of 5 kg.

[0183] According to another example, the melting point (Tm) of each thermoplastic resin layer may gradually decrease as it moves from the first thermoplastic resin layer (110) toward the n-th thermoplastic resin layer. At this time, the content of the fluororesin filler having a low melting point (Tm) in the resin composition forming each thermoplastic resin layer may be adjusted to gradually increase as it moves from the first thermoplastic resin layer (110) toward the n-th thermoplastic resin layer.

[0184] For example, the first thermoplastic resin composition forming the first thermoplastic resin layer (111) may mainly include PTFE (Tm: about 317 to 337 °C) as the first inert resin filler, the second thermoplastic resin composition forming the second thermoplastic resin layer (121) may mainly include PFA (Tm: about 302 to 310 °C) as the second inert resin filler, and the third thermoplastic resin composition forming the third thermoplastic resin layer (131) may mainly include FEP (Tm: 260 to 282 °C) as the third fluororesin filler. That is, the content ratio in each resin layer may be adjusted to increase in the order of PTFE -> PFA -> FEP from the first thermoplastic resin layer (111) to the third thermoplastic resin layer (131).

[0185] For another example, the first thermoplastic resin composition forming the first thermoplastic resin layer (111) includes PTFE (Tm: about 317 to 337° C.) and PFA (Tm: about 302 to 310° C.) as first inert resin fillers, and at this time, PTFE is included in a larger amount than PFA (e.g., PTFE: PFA = 2:1 to 10:1 weight ratio), the second thermoplastic resin composition forming the second thermoplastic resin layer (121) includes PFA (Tm: about 302 to 310° C.) and PTFE (Tm: about 317 to 337° C.) as second inert resin fillers in a weight ratio of less than 1:1 to 1:2, and the third thermoplastic resin composition forming the third thermoplastic resin layer (131) includes FEP (Tm: 260 to 282° C.) as third fluororesin fillers. ℃) and PFA (Tm: about 302 to 310 ℃), and at this time, FEP may be included in a larger amount than PFA (e.g., FEP: PFA = 1:1 to 10:1 weight ratio).

[0186] According to another example, when the components and contents of the fluororesin filler in the first thermoplastic resin layer to the n-th thermoplastic resin layer are the same, the content of the inorganic filler in each thermoplastic resin layer can be adjusted to gradually decrease as it goes from the first thermoplastic resin layer (110) to the n-th thermoplastic resin layer.

[0187] The third circuit pattern (132) to the nth circuit pattern are respectively arranged on one surface of the third thermoplastic resin layer (131) to the nth thermoplastic resin layer, and are patterned in a predetermined shape having a predetermined width and thickness (here, n is an integer greater than or equal to 3, specifically an integer from 3 to 10). The third circuit pattern (132) to the nth circuit pattern can each perform various functions according to the design of the corresponding layer, and can be, for example, a power supply line, a ground line, a ground electrode, etc. In this way, the third circuit pattern (132) to the nth circuit pattern can each be electrically connected to a circuit pattern in another substrate [e.g., a first circuit pattern (112), a second circuit pattern (122), etc.] through a via.

[0188] Descriptions of the materials forming each of the third circuit pattern (132) to the n-th circuit pattern are omitted because they are the same as those described in the first circuit pattern (112). According to an example, the materials of each of the third circuit pattern (132) to the n-th circuit pattern may be copper (Cu).

[0189] As described above, the multilayer printed circuit board (100A, 100B) of the present invention is built up with circuit boards (110, 120, 130) through adhesion between single materials without a heterogeneous interface. The multilayer printed circuit board (100A, 100B) according to the present invention can not only realize environmental reliability and low dielectric loss in the high-frequency range, but also improve processability. In addition, the multilayer printed circuit board (100A, 100B) according to the present invention can improve high heat resistance and low dielectric properties. Therefore, the multilayer printed circuit board of the present invention can be usefully applied to various electric, electronic, and communication devices such as mobile communication devices or base station devices thereof, servers, routers, and other network-related electronic devices that handle high-frequency or ultra-high-frequency signals, large computers, and automotive radar devices.

[0190] The multilayer printed circuit board according to the present invention can be manufactured by various methods. However, unlike the conventional method, the present invention does not perform the cutting and welding processes of the bonding sheet in manufacturing the multilayer printed circuit board, thereby simplifying the manufacturing process, thereby reducing the manufacturing cost and shortening the process time, thereby improving productivity. In addition, the present invention can easily manufacture a roll-type multilayer printed circuit board by applying a roll-to-roll process, particularly a roll-to-roll process using a belt press.

[0191] FIGS. 4A to 4F are cross-sectional views schematically showing a process for manufacturing a multilayer printed circuit board according to a third embodiment of the present invention.

[0192] According to an example, a method for manufacturing a multilayer printed circuit board according to a third embodiment of the present invention includes, as illustrated in FIGS. 4a to 4f, (S10) a step of preparing a first circuit board (110) including a first thermoplastic resin layer (111) and a first circuit pattern (112) disposed on at least one surface of the first thermoplastic resin layer (111); (S20) a step of preparing a metal laminate (120a) including a metal foil (122a) and a dry film (121a) of a thermoplastic resin composition disposed on one surface of the metal foil (122a); (S30) a step of laminating the metal laminate (120a) on at least one surface of the first circuit board (110) to form a multilayer laminate; (S40) a step of hot pressing the multilayer laminate; And (S50) a step of forming a second circuit pattern (122) on a metal foil (122a) of the multilayer laminate to form a second circuit board (120); and the MFR of the dry film (121a) is adjusted to be greater than the MFR of the first thermoplastic resin layer (111). Optionally, the method for manufacturing a multilayer printed circuit board according to the third embodiment of the present invention may additionally include, before or after forming the second circuit pattern (122), (S60) a step of forming a plurality of holes (H) in the multilayer laminate; and (S70) a step of forming a via by plating the plurality of holes.In addition, the method for manufacturing a multilayer printed circuit board according to the third embodiment of the present invention additionally includes, after the hole plating step ('(S70) step'), the step of preparing an nth metal laminate including an nth metal foil and an nth dry film of an nth thermoplastic resin composition disposed on one surface of the nth metal foil (S80); and the step of forming the multilayer laminate ('(S30) step') to the hole plating step ('(S70) step') are repeatedly performed once or a plurality of times, but the nth metal laminate is used instead of the metal laminate to form the multilayer laminate, and the MFR of each dry film can be controlled to gradually increase from the n-2th dry film to the nth dry film, and n can be an integer of 3 or more, specifically, an integer of 3 to 10. However, the present invention is not limited thereto, and the following steps do not have to be performed sequentially to manufacture the multilayer laminate, but the steps of each process can be modified or selectively mixed and performed according to the design specifications. In particular, there is no temporal precedence between steps (S10) and (S20).

[0193] Hereinafter, with reference to FIGS. 4a to 4f, each step of a method for manufacturing a multilayer printed circuit board according to the third embodiment of the present invention will be described.

[0194] (a) Preparation stage of the first circuit board

[0195] As shown in Fig. 4a, a first circuit board (110) including a first thermoplastic resin layer (111) and a first circuit pattern (112) arranged on at least one surface of the first thermoplastic resin layer (111) is prepared (hereinafter, '(S10) step').

[0196] The first circuit board (110) used in the present invention may be of panel type or roll type. For example, the first circuit board (110) may be a roll-type double-sided circuit board, specifically, a roll-type double-sided flexible circuit board.

[0197] Descriptions of the first thermoplastic resin layer (111) and the first circuit pattern (112) of the first circuit board (110) are omitted because they are the same as those described in the first embodiment section.

[0198] This first circuit board (110) can be manufactured through various methods known in the art.

[0199] For example, it can be manufactured by continuously supplying a roll-type metal laminate using a roll-to-roll device, opening a hole in the metal laminate to perform through-hole plating, and then etching a metal foil (e.g., copper foil) including a plating film to form a circuit.

[0200] The above metal laminate (hereinafter, “first metal laminate”) includes a first thermoplastic resin layer; and metal foils disposed on each of both sides thereof, and may be of roll type.

[0201] These roll type first metal laminates can be manufactured by various methods known in the art.

[0202] For example, a roll-type first metal laminate may include a step of continuously forming a roll-type first unit member including a dry film (hereinafter, "1A dry film") of the 1A metal foil and the 1A thermoplastic resin composition by applying a 1A thermoplastic resin composition on one surface of a continuously supplied 1A metal foil and drying it; a step of continuously forming a roll-type second unit member including a 1B metal foil and a dry film (hereinafter, "1B dry film") of the 1B thermoplastic resin composition by applying a 1B thermoplastic resin composition on one surface of a continuously supplied 1B metal foil and drying it; and a step of stacking a second unit member on the first unit member such that the dry films of the respective unit members are in contact with each other, and then heating and pressurizing. Optionally, a fiber-containing substrate may be disposed between the dry films.

[0203] The first and second unit members are roll-type members in which each resin composition is directly applied (coated) onto one surface of a metal foil, and then dried, so that a dry film in which the solvent is removed from the applied resin composition is formed on one surface of each metal foil. These first and second unit members can be manufactured by directly coating and drying each resin composition onto each metal foil, without a film forming process and a high-temperature firing process. At this time, since the dry films have excellent adhesion to the metal foil, the durability of the metal laminate can be improved.

[0204] The above 1A thermoplastic resin composition comprises a 1A fluororesin filler, a 1A inorganic filler, and a 1A binder resin, and may optionally comprise a 1A organic solvent.

[0205] The above 1B thermoplastic resin composition is the same as or different from the 1A thermoplastic resin composition, and includes a 1B fluorine resin filler, a 1B inorganic filler, and a 1B binder resin, and may optionally include a 1B organic solvent.

[0206] Descriptions of the respective components of the first A and first B thermoplastic resin compositions are omitted because they are the same as those described in the first thermoplastic resin composition.

[0207] The above-mentioned metal foils 1A and 1B can be used without any particular limitation as long as they are conventional metal components applied to metal laminates or printed circuit boards in the relevant field. For example, each metal foil can be a metal thin film selected from the group consisting of copper (Cu), iron (Fe), nickel (Ni), titanium (Ti), aluminum (Al), silver (Ag), and gold (Au), or an alloy thin film of two or more types. Preferably, the first metal foil (13A) can be a copper foil having excellent electrical conductivity and low price. In this case, the copper foil can be any conventional copper foil known in the relevant field without limitation, and any copper foil manufactured by a rolling method or an electrolytic method can be used.

[0208] The surface roughness of the above 1A and 1B metal foils is not particularly limited, and may be, for example, about 0.5 to 3 ㎛ each.

[0209] In addition, the thickness of the first A and first B metal foils is not particularly limited, and may be in the range of about 1 to 50 μm, specifically, in the range of about 1 to 30 μm, taking into account the thickness and mechanical properties of the metal laminate.

[0210] The above direct application (coating) method is not particularly limited, and includes, for example, roll-to-roll coating, and specifically, comma coating, slot die coating, curtain coating, and spray coating.

[0211] The drying process of the above-mentioned 1A and 1B resin compositions is to dry the 1A and 1B thermoplastic resin compositions, and particularly to remove the organic solvent within the compositions. This drying process can be performed at a temperature of about 100 to 180°C for about 3 to 30 minutes. As a result, a dry film of the resin composition can be formed on each metal foil. In this way, the present invention only dries each resin composition prior to the heating and pressurizing process of the first and second unit members, and does not perform a high-temperature firing process of 350°C or higher.

[0212] The first and second unit members obtained as described above are laminated, and then heated and pressed. However, the laminate is performed so that the dry films of each unit member are in contact with each other. Optionally, a fiber-containing substrate may be placed between the dry films.

[0213] For example, the first and second unit members can be laminated on both sides of a fiber-containing substrate continuously supplied from a fiber-containing substrate supply roller, and then these can be thermally bonded at 300 to 340°C. At this time, the unit members are continuously supplied and laminated and thermally bonded so that the dry film of each unit member is in contact with the fiber-containing substrate.

[0214] The description of the above fiber-containing substrate is omitted because it is the same as that described in the first embodiment section.

[0215] In the above thermocompression bonding, a hot press device, a pair of pressurized heating rollers, or a belt press can be used. At this time, each unit member can be heated and pressed at a pressure (e.g., linear pressure) of about 10 to 50 kgf / ㎤ per 1 m and a temperature of about 250 to 400 ℃ for about 1 to 2 hours. Through this thermocompression bonding process, each dry film is (completely) solidified, thereby obtaining a first metal laminate including a first A metal foil / first thermoplastic resin layer / first B metal foil, and optionally further including 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.

[0216] The first metal laminate of the roll type manufactured as described above can be manufactured into a first circuit board (110) through a hole processing process, a hole plating process, a circuit pattern forming process, etc., which are commonly known in the art. For example, a plurality of holes are continuously formed in a first metal laminate continuously supplied by a roll-to-roll device, and then each hole formed is plated, and a photoresist film or the like is laminated on a metal foil (e.g., copper foil) including a plating film, and then exposed, developed, and etched to form a first circuit pattern (112). As a result, a first circuit board (110) including a first thermoplastic resin layer (111) and first circuit patterns (112) respectively disposed on both surfaces thereof can be obtained.

[0217] The device used in the above hole processing is not particularly limited as long as it is a device capable of opening a hole in a metal laminate, and includes, for example, a punching machine such as a metal punching machine or a rotary punching machine, a laser device, etc.

[0218] Alkaline developers that can be used in the above development process include, but are not limited to, aqueous solutions of quaternary ammonium hydroxides such as tetramethylammonium hydroxide and tetraethylammonium hydroxide; aqueous solutions of amines such as ammonia, ethylamine, diethylamine, and triethylamine.

[0219] The etchant that can be used in the above etching treatment process is not particularly limited as long as it is a generally used etchant in the art, and for example, an etchant such as hydrogen peroxide / hydrochloric acid (H2O2 / HCl); a copper etchant such as cupric chloride (CuCl2) or ferric chloride (FeCl3); or an etchant such as CNNBSA (3-nitrobenzene sulfonic acid) / PEI (polyethylenimine) can be used alone or in an appropriate mixture.

[0220] (b) Preparation stage of metal laminate

[0221] As illustrated in Fig. 4b, a metal laminate (120a) is prepared (hereinafter, 'step (S20)'). This step (S20) has no temporal precedence with the step (S10).

[0222] The metal laminate (hereinafter, “second metal laminate”) (120a) obtained in the above step (S20) is of panel type or roll type, and includes a metal foil (hereinafter, “second metal foil”) (122a); and a dry film (hereinafter, “second dry film”) (121a) of a second thermoplastic resin composition disposed on one surface of the metal foil (122a).

[0223] This second metal laminate can be manufactured through various methods known in the art. For example, a second thermoplastic resin composition (C2) can be directly applied onto one surface of a second metal foil (122a) and dried to obtain a second metal laminate (120a) including a second metal foil (122a) and a second dry film (121a). In this case, when a roll-to-roll device is used, the second dry film (121a) can be continuously formed on the second metal foil (122a) continuously supplied from a metal foil supply roller to obtain a roll-type second metal laminate (120a).

[0224] The above second metal foil (122a) may be different from or identical to the first A and first B metal foils. Since the description of the second metal foil (122a) is the same as that described in the first A and first B metal foil sections, it is omitted.

[0225] Since the description of the second thermoplastic resin composition (C2) is the same as that described in the first embodiment section, it is omitted.

[0226] The above coating method is not particularly limited, and includes, for example, roll-to-roll coating, and specifically, comma coating, slot die coating, curtain coating, and spray coating.

[0227] The above drying process is to dry the second thermoplastic resin composition, and in particular, to remove the organic solvent within the composition. This drying process can be performed at a temperature of about 100°C or lower, specifically about 30 to 80°C, for about 1 to 5 minutes. As a result, a second metal laminate (120a) can be obtained in which a second dried film (121a) in which the second thermoplastic resin composition (C2) is dried is formed on a second metal foil (122a). In this way, the present invention only dries the second thermoplastic resin composition and does not perform a high-temperature firing process of 300°C or higher. Therefore, the second dried film (121a) obtained through the above drying process can be a sponge-shaped insulating layer having numerous pores therein.

[0228] However, in the present invention, the MFR of the second drying film (121a) is adjusted to be greater than the MFR of the first thermoplastic resin layer (111) of the first circuit board (110) described above. Accordingly, in the present invention, the second metal laminate (120a) can be laminated with the first circuit board (110) obtained in the above step (S10) without a bonding sheet in the following step (S40), and at this time, the dimensional stability of the first circuit board (110) can be prevented from being deteriorated.

[0229] (c) Formation stage of multilayer laminate

[0230] As illustrated in Fig. 4c, the second metal laminate (120a) obtained in step (S20) is laminated on at least one surface of the first circuit board (110) obtained in step (S10) to form a multilayer laminate (hereinafter, 'step (S30)'). At this time, the second dry film (121a) of the second metal laminate (120a) comes into contact with the first circuit board (110).

[0231] The multilayer laminate (hereinafter, “1A multilayer laminate”) obtained in the above step (S30) may include a first circuit board (110); and a second metal laminate (120a) disposed on each of both sides of the first circuit board (110). Specifically, the 1A multilayer laminate may have a structure in which the second metal foil (122a) / second dry film (121a) / first circuit pattern (112) / first thermoplastic resin layer (111) / first circuit pattern (112) / second dry film (121a) / second metal foil (122a) are laminated in this order. At this time, the second dry film (121a) may be in contact with not only the first circuit pattern (112) but also the first thermoplastic resin layer (111).

[0232] (d) Hot press step of multilayer laminate

[0233] As shown in Fig. 4d, the first A multilayer laminate obtained in step (S30) is hot pressed (hereinafter, 'step (S40)').

[0234] Since both the second dry film (121a) and the first thermoplastic resin layer (111) in the above 1A multilayer laminate contain thermoplastic components, they can be plastically deformed by heat. Therefore, when the 1A multilayer laminate is hot-pressed, the second dry film (121a) is melted by heat, has fluidity, and spreads. At this time, the first thermoplastic resin layer (111) can be melted or non-melted. If the first thermoplastic resin layer (111) is also melted by heat, since the MFR of the first thermoplastic resin layer (111) is smaller than the MFR 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) has fluidity and spreads. The components of the second dry film (121a) that are spread and the components of the first thermoplastic resin layer (111) can be mixed with each other at the interface to fill the space between the first circuit patterns (112) without air bubbles. Thereafter, when the 1A multilayer laminate is cooled, the molten second dry film (121a) solidifies into the 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 attached and integrated as one film without a different interface. Therefore, the printed circuit board of the present invention can include a first circuit board (110) and a second circuit board (120) that are directly attached to each other without a bonding sheet.

[0235] The step (S40) above may include a step (S41) of compression-molding the multilayer laminate obtained in the step (S30); and a step (S42) of sintering the compression-molded multilayer laminate.

[0236] The above compression molding step (hereinafter, '(S41) step') is a low-temperature, high-pressure compression molding process. In the (S41) step, when pressure is applied to the second dry film (122a), the second fluororesin fillers in the second dry film (122a) are compressed by the high pressure, thereby removing air bubbles between the fillers. The (S41) step may be performed for about 30 to 90 minutes under a pressure in the range of about 3 to 5 MPa. During the compression molding, the multilayer laminate may be preheated. The preheating temperature is not particularly limited, but is preferably lower than the melting point (Tm) of the second dry film, specifically lower than the melting point (Tm) of the second fluororesin filler. For example, the preheating temperature may be lower than 300°C, specifically about 200 to 280°C. In this case, this is based on the actual temperature applied to an actual product, and actual press conditions may be different.

[0237] The above-mentioned firing step (hereinafter, '(S42) step') is preferably performed under a lower pressure than the above-mentioned compression molding step. Thus, the fluidity of the first thermoplastic resin layer (111) during firing can be minimized, thereby ensuring dimensional stability. In one example, the above-mentioned (S42) step can be performed under a pressure of less than 2 MPa, specifically, about 0.5 to 1 MPa.

[0238] This (S42) step may include a step of heat-treating the compression-molded multilayer laminate at a temperature higher than the melting point (Tm) of the second dry film and a pressure lower than the pressure during the compression molding; a step of stabilizing the heat-treated multilayer laminate while applying pressure up to the pressure during the compression molding at a temperature lower than the melting point (Tm) of the second dry film; and a step of cooling the stabilized multilayer laminate.

[0239] Examples of the heat treatment temperature include about 305°C or higher, specifically about 330 to 380°C, and more specifically about 330 to 350°C. In one embodiment, the heat treatment step may be performed at a temperature of about 305°C or higher, at a pressure lower than the pressure during compression molding, for example, at a pressure of about 0.5 to 2 MPa, for about 30 to 90 minutes. In this case, the fluidity of the second fluororesin filler within the second drying film (121a) may be further improved, thereby further enhancing the diffusion effect.

[0240] The stabilization step may be performed, for example, at a temperature below about 300°C, specifically about 200 to 280°C, and more specifically about 250 to 280°C. In one example, the stabilization step stabilizes the heat-treated multilayer laminate while applying pressure at a temperature below 300°C, for example, up to a pressure of about 3 to 5 MPa during compression molding. This ensures thickness stability of each resin layer.

[0241] The above cooling step can be performed under the same pressure as the above stabilization step while cooling the stabilized multilayer laminate.

[0242] (e) Second circuit pattern formation step

[0243] As illustrated in FIG. 4e, the second metal foil (122a) of the hot-pressed multilayer laminate in step (S40) is processed into a second circuit pattern (122) (hereinafter, 'step (S50)'). Thus, the present invention can manufacture a multilayer printed circuit board having a structure of second circuit board (120) / first circuit board (110) / second circuit board (120) without including a bonding sheet (see FIG. 1).

[0244] In the above step (S50), a photoresist film or the like is laminated on the second metal foil (122a), then exposed, developed, and then etched to form a second circuit pattern (122).

[0245] The above exposure process forms a cured area and a non-cured area by exposure, and depending on whether the photoresist film is positive or negative, the non-exposed area or the exposed area is later removed by a developer.

[0246] This exposure process can be performed using an excimer laser, ultraviolet rays, ultraviolet rays, visible light, electron rays, X-rays, or g-rays (wavelength about 436 nm), i-rays (wavelength about 365 nm), h-rays (wavelength about 405 nm), or a mixture of these rays.

[0247] The above development process removes uncured areas by developing a partially exposed photoresist film with an alkaline developer. Examples of the alkaline developer include, but are not limited to, aqueous solutions of quaternary ammonium hydroxides such as tetramethyl ammonium hydroxide and tetraethyl ammonium hydroxide; aqueous solutions of amines such as ammonia, ethylamine, diethylamine, and triethylamine.

[0248] The above etching treatment process forms a second circuit pattern (122) by etching a portion of a second metal foil from which a certain area of ​​a photoresist film has been removed using an etchant. Non-limiting examples of the etchant include a hydrogen peroxide / hydrochloric acid (H2O2 / HCl) etchant; a copper etchant such as cupric chloride (CuCl2) or ferric chloride (FeCl3); or CNNBSA (3-nitrobenzene sulfonic acid) / PEI (polyethylenimine), and these may be used alone or in an appropriate combination of two or more.

[0249] Optionally, in the present invention, before or after forming the second circuit pattern, a plurality of holes may be formed in the hot-pressed multilayer laminate, and then the plurality of holes may be plated to form vias (see FIGS. 4e and 4f).

[0250] The device used in the above hole processing is not particularly limited as long as it is a device capable of opening a hole in a metal laminate, and includes, for example, a punching machine such as a metal punching machine or a rotary punching machine, a laser device, etc.

[0251] The method for forming the above plating film is not particularly limited and can be performed according to a conventional method known in the art.

[0252] (f) Repeated performance of the formation step or hole plating step of a multilayer laminated plate

[0253] Optionally, the present invention further includes a 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 surface of the nth metal foil after the hole plating step; and the step of forming the multilayer laminate or the hole plating step may be repeated once or a plurality of times (wherein, n is an integer of 3 or more). In this case, a multilayer laminate (hereinafter, “2A multilayer laminate”) may be formed using the nth metal laminate instead of the metal laminate. However, in the present invention, in order to manufacture a multilayer printed circuit board to which individual circuit boards are attached without a bonding sheet, the MFR of each dry film is gradually adjusted to increase from the n-2th dry film to the nth dry film.

[0254] For example, the present invention can prepare a third metal laminate including a third metal foil and a third dry film of a third thermoplastic resin composition disposed on one surface of the third metal foil after the hole plating step. At this time, the MFR of the third dry film is adjusted to be greater than the MFR of the second dry film. Thereafter, the prepared third metal laminate is laminated on each of the second circuit boards (120) of the multilayer printed circuit board obtained in the step (S50) to form a secondA multilayer laminate, and then, after hot pressing the secondA multilayer laminate, the third metal foil is processed into a third circuit pattern, and after hole processing, hole plating is performed, thereby obtaining a multilayer printed circuit board having a structure of third circuit board (130) / second circuit board (120) / first circuit board (110) / second circuit board (120) / third circuit board (130) (see FIG. 2).

[0255] Next, by repeatedly performing the steps of preparing an n-th metal laminate, forming a multilayer laminate, hot pressing, forming a circuit pattern, processing a hole, and plating a hole, a multilayer printed circuit board having a structure of an n-th circuit board / … / third circuit board (130) / second circuit board (120) / first circuit board (110) / second circuit board (120) / third circuit board (130) / … / n-th circuit board can be manufactured, wherein n is an integer of 3 or more, for example, an integer of 3 to 10. The n-th metal laminate includes an n-th metal foil and an n-th dry film of a thermoplastic resin composition disposed on one surface of the n-th metal foil. At this time, the MFR of each dry film is controlled to gradually increase from the n-2-th dry film to the n-th dry film.

[0256] When performing the above multiple hot press steps, the initial firing maximum temperature can be applied up to about 380°C, and the outermost layer's firing maximum temperature can be about 330°C, but is not limited thereto.

Claims

1. A first circuit board including a first thermoplastic resin layer and a first circuit pattern arranged on at least one surface of the first thermoplastic resin layer; and A second circuit board comprising a second thermoplastic resin layer disposed on at least one surface of the first circuit board, and a second circuit pattern disposed on one surface of the second thermoplastic resin layer Including, A multilayer printed circuit board, wherein the MFR (melt flow rate) of the second thermoplastic resin layer is greater than the MFR of the first thermoplastic resin layer.

2. In paragraph 1, A multilayer printed circuit board, wherein the MFR of the second thermoplastic resin layer is 10 to 100 times higher than the MFR of the first thermoplastic resin layer.

3. In paragraph 1, A multilayer printed circuit board, 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. In paragraph 1, A multilayer printed circuit board, wherein the MFR of the second thermoplastic resin layer is more than 1 g / 10 min and less than or equal to 5 g / 10 min at a temperature of 372° C. and a load of 5 kg.

5. In paragraph 1, The first thermoplastic resin layer is formed of a first thermoplastic resin composition including a first fluorine resin filler, a first inorganic filler, and a first binder resin, The second thermoplastic resin layer is formed of a second thermoplastic resin composition including a second fluorine resin filler, a second inorganic filler, and a second binder resin. A multilayer printed circuit board, wherein the MFR of the second fluorine resin filler is greater than the MFR of the first fluorine resin filler.

6. In paragraph 5, A multilayer printed circuit board, wherein the MFR of the second fluorine resin filler is 2 to 20 times greater than the MFR of the first fluorine resin filler.

7. In paragraph 5, A multilayer printed circuit board, 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. In paragraph 1, A multilayer printed circuit board, wherein the second thermoplastic resin layer is directly attached to the first circuit board.

9. In paragraph 1, A multilayer printed circuit board having a fiber-containing substrate embedded within the first thermoplastic resin layer.

10. In paragraph 1, In addition, a third circuit board to an nth circuit board are sequentially arranged on the second circuit board, The third circuit board includes a third thermoplastic resin layer arranged on the second circuit board, and a third circuit pattern arranged on one surface of the third thermoplastic resin layer. The above nth circuit board includes an nth thermoplastic resin layer arranged on the n-1th circuit board, and an nth circuit pattern arranged on one surface of the nth thermoplastic resin layer. As the second thermoplastic resin layer moves toward the nth thermoplastic resin layer, the MFR of each thermoplastic resin layer gradually increases. A multilayer printed circuit board, wherein n is 3 or more.

11. In paragraph 10, A multilayer printed circuit board, wherein, as one moves from the second thermoplastic resin layer to the nth thermoplastic resin layer, the MFR of each thermoplastic resin layer gradually increases by 2 to 10 times.

12. In paragraph 11, A multilayer printed circuit board, wherein the melting point (Tm) of each thermoplastic resin layer gradually decreases as it moves from the first thermoplastic resin layer to the nth thermoplastic resin layer.

13. A step of preparing a first circuit board including a first thermoplastic resin layer and a first circuit pattern arranged on at least one surface of the first thermoplastic resin layer; A step of preparing a metal laminate comprising a metal foil and a dry film of a thermoplastic resin composition disposed on one surface of the metal foil; A step of forming a multilayer laminate by laminating the metal laminate on at least one surface of the first circuit board; A step of hot pressing the above multilayer laminate; and A step of forming a second circuit pattern on a metal foil of the above hot-pressed multilayer laminate; Including, A method for manufacturing a multilayer printed circuit board, wherein the MFR of the above-mentioned drying film is adjusted to be greater than the MFR of the above-mentioned first thermoplastic resin layer.

14. In paragraph 13, The above hot press step A step of compression molding the multilayer laminated plate; and A step of sintering the above compression-molded multilayer laminated plate. Including, A method for manufacturing a multilayer printed circuit board, wherein the above-mentioned firing step is performed under a lower pressure than the above-mentioned compression molding step.

15. In paragraph 14, A method for manufacturing a multilayer printed circuit board, wherein the compression molding step is performed under a pressure in the range of 3 to 5 MPa.

16. In paragraph 14, The above firing step A step of heat-treating the compression-molded multilayer laminate at a temperature higher than the melting point (Tm) of the dry film and a pressure lower than the pressure at the time of compression molding; A step of stabilizing the heat-treated multilayer laminate while applying pressure to the compression molding pressure at a temperature lower than the melting point (Tm) of the dry film; and A step of cooling the above stabilized multilayer laminate. A method for manufacturing a multilayer printed circuit board, comprising:

17. In paragraph 13, Before the formation of the second circuit pattern, A step of forming a plurality of holes in the hot-pressed multilayer laminate; and Step of plating the above plurality of holes A method for manufacturing a multilayer printed circuit board, the method further comprising:

18. In paragraph 17, After the above hole plating step, A 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 surface of the nth metal foil; further comprising; The above multilayer laminate forming step or hole plating step is performed once or multiple times repeatedly. A multilayer laminate is formed by using the nth metal laminate instead of the above metal laminate, In the above n-2 drying film, the MFR of each drying film is gradually increased as it goes to the n-th drying film. A method for manufacturing a multilayer printed circuit board, wherein n is an integer greater than or equal to 3.

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