Brown-treatment-free embedded resistor-buried copper foil and printed circuit board

Abstract

The invention belongs to the technical field of electronic circuit materials, and particularly relates to a browning-free embedded resistor-buried copper foil and a printed circuit board. Compared with the prior art, the method has the advantages that the bonding force between the original smooth surface and the prepreg is improved by roughening the original smooth surface, and the browning process of the downstream PCB before lamination of the prepreg is replaced. And the damage of browning liquid medicine to the exposed resistance material is avoided, so that the problem that the resistance value consistency of the buried resistance copper foil is seriously drifted after the downstream PCB is processed is reduced. And a browning process before lamination of the prepreg is canceled, so that the processing cost of the PCB is reduced, the scrap rate is reduced, and the yield is improved.

Description

Technical Field

[0001] This invention belongs to the field of electronic circuit materials technology, and particularly relates to an embedded buried copper foil and printed circuit board that are free from browning treatment. Background Technology

[0002] With the application of 5G communication technology and the surge in high-speed, high-performance electronic products, the development of printed circuit boards (PCBs) is trending towards miniaturization, easy packaging, and high-frequency, high-speed characteristics. Traditional passive component mounting increases the number of pads on the PCB surface, reduces the usable surface area, and increases parasitic effects between pad components, leading to instability in high-frequency signal transmission. Employing embedded technology to integrate passive components such as resistors into a single unit, replacing conventional surface-mount resistors, has become an important means of solving this problem.

[0003] Embedded copper foil is an ideal product for making embedded resistor PCBs, playing an important role in resistor power amplification, voltage conversion, signal input / output, temperature compensation, and power supply filtering.

[0004] However, during the downstream PCB manufacturing process, the resistance consistency of buried copper foil typically increases by more than 10%. These variations are mainly due to the PCB manufacturing process, especially the browning process before laminating the prepreg. Browning aims to improve the adhesion between the copper foil and the prepreg, but the browning chemicals can damage the exposed resistive material, leading to significant resistance drift. Combined with the inherent tolerance fluctuations of the buried copper foil material itself, the overall product consistency can spike to over 15%, severely impacting the reliability of subsequent applications. Summary of the Invention

[0005] In view of this, the technical problem to be solved by the present invention is to provide an embedded copper foil and a printed circuit board that do not require browning treatment.

[0006] This invention provides an embedded copper foil without browning treatment, comprising:

[0007] Raw foil; the raw foil includes two surfaces, namely surface A and surface B opposite to surface A;

[0008] The A-side is sequentially provided with a first roughening layer, a resistive material layer, a first anti-oxidation layer, and a silane layer;

[0009] The B-side is sequentially provided with a second roughening layer and a second anti-oxidation layer;

[0010] The surface roughness Rz of the first roughening layer and the second roughening layer is 1~15 micrometers.

[0011] Preferably, the first roughening layer and the second roughening layer are each formed independently by electroplating copper nodules or reverse etching on the surface of the green foil.

[0012] Preferably, the first roughening layer is formed by electroplating copper nodules on the A side of the green foil, and the surface roughness Rz of the A side of the green foil is 0.2~10 micrometers;

[0013] And / or, the second roughening layer is formed by electroplating copper nodules onto the B side of the green foil, wherein the surface roughness Rz of the B side of the green foil is 0.2 to 2 micrometers.

[0014] Preferably, the electroplated copper nodule includes a roughening treatment and a curing treatment; the electroplating solution for the roughening treatment includes: 10~30 g / L copper ions, 100~150 g / L sulfuric acid and 5~25 mg / L tungsten ions;

[0015] The electroplating solution used for the curing process contains 30-60 g / L copper ions and 80-120 g / L sulfuric acid.

[0016] Preferably, the temperature of the roughening treatment is 20℃~40℃; the current density of the roughening treatment is 10~30 A / dm. 2 ;

[0017] The roughening process takes 5-30 seconds.

[0018] The curing temperature is 40℃~60℃;

[0019] The current density of the curing process is 10~30 A / dm. 2 ;

[0020] The curing process takes 5 to 30 seconds.

[0021] Preferably, the etching solution for reverse etching is a dilute sulfuric acid solution of 20~100 g / L.

[0022] The temperature for the reverse etching is 30℃~60℃;

[0023] The reverse etching time is 5~15s.

[0024] Preferably, the sheet resistance of the resistive material layer is 10~200Ω / □.

[0025] Preferably, the first anti-oxidation layer and the second anti-oxidation layer each independently comprise one or more of nickel, cobalt, zinc, molybdenum, indium, and chromium; the content of one or more of nickel, cobalt, zinc, molybdenum, indium, and chromium in the first and second anti-oxidation layers is independently 1~500 mg / m³. 2 .

[0026] Preferably, the thickness of the silane layer is 0.1~80 nm.

[0027] Preferably, the silane layer comprises one or more of epoxy silanes, amino silanes, mercapto silanes, vinyl silanes, ureosilanes, acrylic silanes, and fluorinated silanes.

[0028] Compared to existing technologies, this invention improves the adhesion between the prepreg and the prepreg by roughening the originally smooth surface, replacing the browning process before prepreg lamination in downstream PCB manufacturing. This avoids damage to the exposed resistive material caused by the browning solution, thereby reducing the problem of severe resistance inconsistency drift in buried copper foil after downstream PCB processing. Eliminating the browning process before prepreg lamination reduces PCB processing costs, decreases scrap, and improves yield.

[0029] Experimental results show that the embedded copper foil without browning treatment provided by the present invention can reduce the problem of severe resistance value drift after downstream PCB processing, so that the finished product tolerance can be controlled within 7%, and preferably within 4%. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the structure of an embedded copper foil that is exempt from browning treatment, provided by the present invention.

[0031] Figure 2 This is a schematic diagram of the structure of an embedded copper foil that is exempt from browning treatment, provided by the present invention.

[0032] Figure 3 This is a schematic diagram of the structure of an embedded copper foil that is exempt from browning treatment, provided by the present invention.

[0033] Figure 4 This is a schematic diagram of an embedded copper foil that is exempt from browning treatment, provided by the present invention. Detailed Implementation

[0034] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0035] This invention provides an embedded copper foil without browning treatment, comprising: a raw foil; the raw foil includes two surfaces, namely surface A and surface B opposite to surface A; surface A is sequentially provided with a first roughening layer, a resistive material layer, a first anti-oxidation layer and a silane layer; surface B is sequentially provided with a second roughening layer and a second anti-oxidation layer; the surface roughness Rz of the first roughening layer and the second roughening layer is 1~15 micrometers.

[0036] The embedded copper foil provided by this invention includes a first roughening layer and a second roughening layer, which can ensure that the copper foil and the prepreg have a high bonding force without browning in the downstream PCB. Furthermore, eliminating the browning process can avoid the corrosion of the exposed resistive layer material by chemicals, thereby reducing the problem of resistance consistency drift in the downstream processing of the embedded copper foil.

[0037] In one specific embodiment of the present invention, the green foil can be obtained by electrolysis or by rolling, without any particular limitation; the thickness of the green foil is preferably 9~35 μm; optionally, the thickness of the green foil is 9 μm, 12 μm, 15 μm, 18 μm, 21 μm, 24 μm, 27 μm, 30 μm, 32 μm, 35 μm or any two of the above values.

[0038] In this invention, the green foil includes two surfaces, namely surface A and surface B opposite to surface A; surface A is sequentially provided with a first roughening layer, a resistive material layer, a first anti-oxidation layer and a silane layer.

[0039] In one specific embodiment of the present invention, the surface roughness Rz of the first roughening layer is 1 to 15 micrometers; optionally, the surface roughness Rz of the first roughening layer is 1 micrometer, 2 micrometers, 3 micrometers, 4 micrometers, 5 micrometers, 6 micrometers, 7 micrometers, 8 micrometers, 9 micrometers, 10 micrometers, 11 micrometers, 12 micrometers, 13 micrometers, 14 micrometers, 15 micrometers or any two of the above values.

[0040] In one specific embodiment of the present invention, the first roughening layer is formed by electroplating copper nodules or reverse etching on the surface of the green foil.

[0041] In a specific embodiment of the present invention, the first roughening layer is formed by electroplating copper nodules on the A side of the green foil, wherein the surface roughness Rz of the A side of the green foil is preferably 0.2 to 10 micrometers; optionally, the surface roughness Rz of the A side of the green foil is 0.2 micrometers, 0.5 micrometers, 1 micrometer, 2 micrometers, 3 micrometers, 4 micrometers, 5 micrometers, 6 micrometers, 7 micrometers, 8 micrometers, 9 micrometers, 10 micrometers or any two of the above values.

[0042] In one specific embodiment of the present invention, the electroplated copper nodule includes roughening treatment and curing treatment.

[0043] In a specific embodiment of the present invention, the roughening electroplating solution preferably comprises: 10-30 g / L copper ions, 100-150 g / L sulfuric acid, and 5-25 mg / L tungsten ions; optionally, the concentration of copper ions in the roughening electroplating solution is 10 g / L, 15 g / L, 20 g / L, 25 g / L, 30 g / L, or any two of the above values; the copper ions are preferably provided by copper sulfate; optionally, the concentration of sulfuric acid in the roughening electroplating solution is 100 g / L, 110 g / L, 120 g / L, 130 g / L, 140 g / L, 150 g / L, or any two of the above values; optionally, the concentration of tungsten ions in the roughening electroplating solution is 5 mg / L, 8 mg / L, 10 mg / L, 12 mg / L, 15 mg / L, 18 mg / L, 20 mg / L, 22 mg / L, 25 mg / L, or 25 mg / L. mg / L or a range between any two of the above values; the tungsten ions are preferably provided by tungsten sulfate.

[0044] In a specific embodiment of the present invention, the electroplating solution for roughening treatment preferably includes: 15-20 g / L of copper ions, 120-140 g / L of sulfuric acid and 15-20 mg / L of tungsten ions.

[0045] In one specific embodiment of the present invention, the temperature of the roughening treatment is preferably 20°C to 40°C; optionally, the temperature of the roughening treatment is 20°C, 25°C, 30°C, 35°C, 40°C, or any two of the above values; the current density of the roughening treatment is preferably 10 to 30 A / dm³. 2 Optionally, the current density of the roughening treatment is 10 A / dm. 2 15 A / dm 2 20 A / dm 2 25 A / dm 2 30 A / dm 2 Or the range between any two of the above values; the preferred time for the coarsening process is 5 to 30 seconds; optionally, the time for the coarsening process is 5 seconds, 10 seconds, 15 seconds, 20 seconds, 25 seconds, 30 seconds or the range between any two of the above values.

[0046] In a specific embodiment of the present invention, the temperature of the roughening treatment is preferably 22°C to 28°C; the current density of the roughening treatment is preferably 20 to 30 A / dm³. 2The roughening process is preferably performed for 20 to 30 seconds.

[0047] In a specific embodiment of the present invention, the electroplating solution for the curing treatment preferably comprises 30-60 g / L of copper ions and 80-120 g / L of sulfuric acid; optionally, the concentration of copper ions in the electroplating solution for the curing treatment is 30 g / L, 35 g / L, 40 g / L, 45 g / L, 50 g / L, 55 g / L, 60 g / L or any two of the above values; optionally, the concentration of sulfuric acid in the electroplating solution for the curing treatment is 80 g / L, 85 g / L, 90 g / L, 95 g / L, 100 g / L, 105 g / L, 110 g / L, 115 g / L, 120 g / L or any two of the above values.

[0048] In one specific embodiment of the present invention, the electroplating solution for the curing treatment preferably includes 40-50 g / L of copper ions and 90-100 g / L of sulfuric acid.

[0049] In one specific embodiment of the present invention, the curing temperature is preferably 40℃~60℃; optionally, the curing temperature is 40℃, 45℃, 50℃, 55℃, 60℃ or any two of the above values; the current density of the curing process is preferably 10~30 A / dm³. 2 Optionally, the current density of the roughening treatment is 10 A / dm. 2 15 A / dm 2 20 A / dm 2 25 A / dm 2 30 A / dm 2 Or the range between any two of the above values; the curing time is preferably 5 to 30 s; optionally, the curing time is 5 s, 10 s, 15 s, 20 s, 25 s, 30 s or the range between any two of the above values.

[0050] In a specific embodiment of the present invention, the curing temperature is preferably 45℃~55℃; the curing current density is preferably 20~30 A / dm³. 2 The curing time is preferably 20-30 seconds.

[0051] In another specific embodiment of the present invention, the first roughening layer is formed by reverse etching of the surface of the green foil; in this case, the first roughening layer is not a single layer, but also the A-side of the green foil after etching; the etching solution for reverse etching is preferably a dilute sulfuric acid solution of 20~100 g / L; optionally, the concentration of the dilute sulfuric acid is 20 g / L, 30 g / L, 40 g / L, 50 g / L, 60 g / L, 70 g / L, 80 g / L, 90 g / L, 100 g / L or any two of the above values; the temperature of reverse etching is preferably 30℃~60℃; optionally, the temperature of reverse etching is 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, 60℃ or any two of the above values; the time of reverse etching is preferably 5~15 s; optionally, the time of reverse etching is 5 s, 8 s, 10 s, 12 s, 15 s. s or the range between any two of the above values.

[0052] In another specific embodiment of the present invention, the first roughening layer is formed by reverse etching of the surface of the green foil; the etching solution for reverse etching is preferably a dilute sulfuric acid solution of 60~100 g / L; the temperature for reverse etching is preferably 30℃~50℃; and the time for reverse etching is preferably 10~15 s.

[0053] A resistive material layer is disposed on the surface of the first roughening layer; the sheet resistance of the resistive material layer is preferably 10~200Ω / □; optionally, the sheet resistance of the resistive material layer is 10Ω / □, 15Ω / □, 20Ω / □, 25Ω / □, 30Ω / □, 35Ω / □, 40Ω / □, 45Ω / □, 50Ω / □, 55Ω / □, 60Ω / □, 65Ω / □, 70Ω / □, 75Ω / □, 80Ω / □, 85Ω / □, 90Ω / □, 95Ω / □, 100Ω / □, 110Ω / □, 120Ω / □, 130Ω / □, 140Ω / □, 150Ω / □, 160Ω / □, 170Ω / □, 180Ω / □, 190Ω / □, 200Ω / □, or any two of the above values.

[0054] In one specific embodiment of the present invention, the sheet resistance of the resistive material layer is preferably 25~200Ω / □.

[0055] In one specific embodiment of the present invention, the resistive material layer is preferably made of one or more of CrSiO, NiP, and NiCr.

[0056] In this invention, the resistive material layer can be prepared according to methods well known to those skilled in the art, without any special limitations. Specifically, it can be prepared by methods such as chemical plating, electroplating, physical vapor deposition, and chemical vapor deposition.

[0057] A first anti-oxidation layer is disposed on the surface of the resistive material layer away from the green foil; in a specific embodiment of the present invention, the first anti-oxidation layer preferably includes one or more of nickel, cobalt, zinc, molybdenum, indium, and chromium; the content of one or more of nickel, cobalt, zinc, molybdenum, indium, and chromium in the first anti-oxidation layer is preferably 1~500 mg / m 2 Optionally, the content of one or more of nickel, cobalt, zinc, molybdenum, indium, and chromium in the first anti-oxidation layer is 1 mg / m³. 2 5 mg / m 2 10 mg / m 2 20 mg / m 2 30 mg / m 2 40 mg / m 2 50 mg / m 2 60 mg / m 2 70 mg / m 2 80 mg / m 2 90 mg / m 2 100mg / m 2 110 mg / m 2 120 mg / m 2 130 mg / m 2 140 mg / m 2 150 mg / m 2 160 mg / m 2 170 mg / m 2 180mg / m 2 190 mg / m 2 200 mg / m 2 210 mg / m 2 220 mg / m 2 230 mg / m 2 240 mg / m 2 250 mg / m 2 260mg / m 2 270 mg / m 2 280 mg / m 2 290 mg / m 2 300 mg / m 2 310 mg / m 2 320 mg / m 2330 mg / m 2 340mg / m 2 350 mg / m 2 360 mg / m 2 370 mg / m 2 380 mg / m 2 390 mg / m 2 400 mg / m 2 410 mg / m 2 420mg / m 2 430 mg / m 2 440 mg / m 2 450 mg / m 2 460 mg / m 2 470 mg / m 2 480 mg / m 2 490 mg / m 2 500mg / m 2 Or the range between any two of the above values.

[0058] In this invention, the first anti-oxidation layer can be prepared according to methods well known to those skilled in the art, specifically by methods such as chemical plating, electroplating, physical vapor deposition, and chemical vapor deposition.

[0059] A silane layer is disposed on the surface of the first anti-oxidation layer away from the raw foil; the thickness of the silane layer is preferably 0.1~80 nm; optionally, the thickness of the silane layer is 0.1 nm, 1 nm, 5 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm or any two of the above values.

[0060] In one specific embodiment of the present invention, the silane layer preferably includes one or more of epoxy silanes, amino silanes, mercapto silanes, vinyl silanes, ureo silanes, acrylic silanes, and fluorinated silanes.

[0061] In one specific embodiment of the present invention, the silane layer comprises one or more of 3-(2,3-epoxypropoxy)propyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, and 3-methacryloyloxypropyltrimethoxysilane.

[0062] The B-side of the raw foil is sequentially provided with a second roughening layer and a second anti-oxidation layer.

[0063] In one specific embodiment of the present invention, the surface roughness Rz of the second roughening layer is 1 to 15 micrometers; optionally, the surface roughness Rz of the second roughening layer is 1 micrometer, 2 micrometers, 3 micrometers, 4 micrometers, 5 micrometers, 6 micrometers, 7 micrometers, 8 micrometers, 9 micrometers, 10 micrometers, 11 micrometers, 12 micrometers, 13 micrometers, 14 micrometers, 15 micrometers or any two of the above values.

[0064] In one specific embodiment of the present invention, the second roughening layer is formed by electroplating copper nodules or reverse etching on the surface of the green foil.

[0065] In one specific embodiment of the present invention, the second roughening layer is formed by electroplating copper nodules on the B side of the green foil, wherein the surface roughness Rz of the B side of the green foil is preferably 0.2 to 10 micrometers; optionally, the surface roughness Rz of the B side of the green foil is 0.2 micrometers, 0.5 micrometers, 1 micrometer, 2 micrometers, 3 micrometers, 4 micrometers, 5 micrometers, 6 micrometers, 7 micrometers, 8 micrometers, 9 micrometers, 10 micrometers or any two of the above values.

[0066] In one specific embodiment of the present invention, the electroplated copper nodule includes roughening treatment and curing treatment.

[0067] In a specific embodiment of the present invention, the roughening electroplating solution preferably comprises: 10-30 g / L copper ions, 100-150 g / L sulfuric acid, and 5-25 mg / L tungsten ions; optionally, the concentration of copper ions in the roughening electroplating solution is 10 g / L, 15 g / L, 20 g / L, 25 g / L, 30 g / L, or any two of the above values; the copper ions are preferably provided by copper sulfate; optionally, the concentration of sulfuric acid in the roughening electroplating solution is 100 g / L, 110 g / L, 120 g / L, 130 g / L, 140 g / L, 150 g / L, or any two of the above values; optionally, the concentration of tungsten ions in the roughening electroplating solution is 5 mg / L, 8 mg / L, 10 mg / L, 12 mg / L, 15 mg / L, 18 mg / L, 20 mg / L, 22 mg / L, 25 mg / L, or 25 mg / L. mg / L or a range between any two of the above values; the tungsten ions are preferably provided by tungsten sulfate.

[0068] In a specific embodiment of the present invention, the electroplating solution for roughening treatment preferably includes: 15-20 g / L of copper ions, 120-140 g / L of sulfuric acid and 15-20 mg / L of tungsten ions.

[0069] In one specific embodiment of the present invention, the temperature of the roughening treatment is preferably 20°C to 40°C; optionally, the temperature of the roughening treatment is 20°C, 25°C, 30°C, 35°C, 40°C, or any two of the above values; the current density of the roughening treatment is preferably 10 to 30 A / dm³. 2 Optionally, the current density of the roughening treatment is 10 A / dm. 2 15 A / dm 2 20 A / dm 2 25 A / dm 2 30 A / dm 2 Or the range between any two of the above values; the preferred time for the coarsening process is 5 to 30 seconds; optionally, the time for the coarsening process is 5 seconds, 10 seconds, 15 seconds, 20 seconds, 25 seconds, 30 seconds or the range between any two of the above values.

[0070] In a specific embodiment of the present invention, the temperature of the roughening treatment is preferably 22°C to 28°C; the current density of the roughening treatment is preferably 20 to 30 A / dm³. 2 The roughening process is preferably performed for 20 to 30 seconds.

[0071] In a specific embodiment of the present invention, the electroplating solution for the curing treatment preferably comprises 30-60 g / L of copper ions and 80-120 g / L of sulfuric acid; optionally, the concentration of copper ions in the electroplating solution for the curing treatment is 30 g / L, 35 g / L, 40 g / L, 45 g / L, 50 g / L, 55 g / L, 60 g / L or any two of the above values; optionally, the concentration of sulfuric acid in the electroplating solution for the curing treatment is 80 g / L, 85 g / L, 90 g / L, 95 g / L, 100 g / L, 105 g / L, 110 g / L, 115 g / L, 120 g / L or any two of the above values.

[0072] In one specific embodiment of the present invention, the electroplating solution for the curing treatment preferably includes 40-50 g / L of copper ions and 90-100 g / L of sulfuric acid.

[0073] In one specific embodiment of the present invention, the curing temperature is preferably 40℃~60℃; optionally, the curing temperature is 40℃, 45℃, 50℃, 55℃, 60℃ or any two of the above values; the current density of the curing process is preferably 10~30 A / dm³. 2 Optionally, the current density of the roughening treatment is 10 A / dm. 215 A / dm 2 20 A / dm 2 25 A / dm 2 30 A / dm 2 Or the range between any two of the above values; the curing time is preferably 5 to 30 s; optionally, the curing time is 5 s, 10 s, 15 s, 20 s, 25 s, 30 s or the range between any two of the above values.

[0074] In a specific embodiment of the present invention, the curing temperature is preferably 45℃~55℃; the curing current density is preferably 20~30 A / dm³. 2 The curing time is preferably 20-30 seconds.

[0075] In another specific embodiment of the present invention, the second roughening layer is formed by reverse etching of the surface of the green foil; in this case, the second roughening layer is not a single layer, but also the B-side of the green foil after etching; the etching solution for reverse etching is preferably a dilute sulfuric acid solution of 20~100 g / L; optionally, the concentration of the dilute sulfuric acid is 20 g / L, 30 g / L, 40 g / L, 50 g / L, 60 g / L, 70 g / L, 80 g / L, 90 g / L, 100 g / L or any two of the above values; the temperature of reverse etching is preferably 30℃~60℃; optionally, the temperature of reverse etching is 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, 60℃ or any two of the above values; the time of reverse etching is preferably 5~15 s; optionally, the time of reverse etching is 5 s, 8 s, 10 s, 12 s, 15 s. s or the range between any two of the above values.

[0076] In this invention, the methods for forming the first roughening layer and the second roughening layer can be the same or different, and depending on the methods for forming the first roughening layer and the second roughening layer, the embedded copper foil can have four different structures, see [link to relevant documentation]. Figures 1-4 , Figures 1-4 This is a schematic diagram of an embedded copper foil, where 1 is the raw foil, 2 is the roughening layer, 3 is the resistive material layer, 4 is the anti-oxidation layer, and 5 is the silane layer; Figure 1 Both the first roughening layer and the second roughening layer are formed by electroplating copper nodules onto the surface of the green foil; Figure 2 The first roughening layer is formed by electroplating copper nodules on the surface of the green foil, and the second roughening layer is formed by reverse etching on the surface of the green foil. Figure 3 Both the first roughening layer and the second roughening layer are formed by reverse etching of the surface of the green foil; Figure 4 The first roughening layer is formed by reverse etching of the surface of the green foil, and the second roughening layer is formed by electroplating copper nodules on the surface of the green foil.

[0077] In another specific embodiment of the present invention, the second roughening layer is formed by reverse etching of the surface of the green foil; the etching solution for reverse etching is preferably a dilute sulfuric acid solution of 60~100 g / L; the temperature for reverse etching is preferably 30℃~50℃; and the time for reverse etching is preferably 10~15 s.

[0078] The surface of the second roughening layer is provided with a second anti-oxidation layer; in a specific embodiment of the present invention, the second anti-oxidation layer preferably includes one or more of nickel, cobalt, zinc, molybdenum, indium, and chromium; the content of one or more of nickel, cobalt, zinc, molybdenum, indium, and chromium in the second anti-oxidation layer is preferably 1~500 mg / m³. 2 Optionally, the content of one or more of nickel, cobalt, zinc, molybdenum, indium, and chromium in the second anti-oxidation layer is 1 mg / m³. 2 5 mg / m 2 10 mg / m 2 20mg / m 2 30 mg / m 2 40 mg / m 2 50 mg / m 2 60 mg / m 2 70 mg / m 2 80 mg / m 2 90 mg / m 2 100 mg / m 2 110 mg / m 2 120 mg / m 2 130 mg / m 2 140 mg / m 2 150 mg / m 2 160 mg / m 2 170 mg / m 2 180 mg / m 2 190 mg / m 2 200 mg / m 2 210 mg / m 2 220 mg / m 2 230 mg / m 2 240 mg / m 2 250 mg / m 2 260 mg / m 2 270 mg / m2 280 mg / m 2 290 mg / m 2 300 mg / m 2 310 mg / m 2 320 mg / m 2 330 mg / m 2 340 mg / m 2 350 mg / m 2 360 mg / m 2 370 mg / m 2 380 mg / m 2 390 mg / m 2 400 mg / m 2 410 mg / m 2 420 mg / m 2 430 mg / m 2 440 mg / m 2 450 mg / m 2 460 mg / m 2 470 mg / m 2 480 mg / m 2 490 mg / m 2 500 mg / m 2 Or the range between any two of the above values.

[0079] In this invention, the second anti-oxidation layer can be prepared according to methods well known to those skilled in the art, specifically by methods such as chemical plating, electroplating, physical vapor deposition, and chemical vapor deposition.

[0080] This invention improves the adhesion between the prepreg and the copper foil by roughening the originally smooth surface, replacing the browning process before prepreg lamination in downstream PCB manufacturing. This avoids damage to the exposed resistive material caused by the browning solution, thus reducing the problem of severe resistance inconsistency drift in buried copper foil after downstream PCB processing. Eliminating the browning process before prepreg lamination reduces PCB processing costs, decreases scrap, and improves yield.

[0081] To further illustrate the present invention, the following describes in detail, with reference to embodiments, an embedded buried copper foil and printed circuit board without browning treatment provided by the present invention.

[0082] All reagents used in the following examples are commercially available.

[0083] Example 1

[0084] Roughening treatment was performed on a 9 μm thick green foil with a surface roughness Rz of 0.2 μm and a smooth surface roughness Rz of 0.2 μm. Reverse etching was used to achieve a post-etching surface roughness Rz of 1.0 μm for both the surface and the smooth surface. The reverse etching conditions were: 60 g / L dilute sulfuric acid solution, 50℃, and 15 s etching time. CrSiO resistive material was then chemically vapor-deposited on the rough surface to achieve a sheet resistance of 200 Ω / □ and a resistance uniformity of 4.8%. Anti-oxidation layers with a cobalt content of 200 mg / m² were then prepared on both the smooth and rough surfaces using chemical vapor deposition. 2 The indium content is 5 mg / m 2 Finally, a 0.1 nm thick layer of 3-(2,3-epoxypropoxy)propyltrimethoxysilane is coated onto the rough surface.

[0085] Example 2

[0086] Roughening treatment was performed on a 12 μm thick green foil with a surface roughness Rz of 2.0 μm and a smooth surface roughness Rz of 0.9 μm. Reverse etching was used to achieve a post-etching surface roughness Rz of 4.0 μm for the rough surface and 1.8 μm for the smooth surface. The reverse etching conditions were: 100 g / L dilute sulfuric acid solution, 30℃, and 10 s etching time. NiP resistive material was then electrolessly plated onto the rough surface to achieve a sheet resistance of 25 Ω / □ and a resistance uniformity of 2.1%. Anti-oxidation layers with a zinc content of 80 mg / m³ were then prepared on both the smooth and rough surfaces using electroless plating. 2 Finally, a 20 nm thick layer of 3-mercaptopropyltrimethoxysilane is coated onto the textured surface.

[0087] Example 3

[0088] A roughening treatment was performed on a green foil with a thickness of 18 μm, a surface roughness Rz of 4.0 μm, and a surface roughness Rz of 1.2 μm. Copper nodule electroplating was then used to achieve a surface roughness Rz of 6.0 μm for the rough surface and 3.0 μm for the surface smooth surface after electroplating. The copper nodule electroplating process included sequential roughening and curing treatments. The roughening treatment electroplating solution included Cu... 2+ The concentrations of H₂SO₄ and tungsten ions were 20 g / L, 140 g / L, and 20 mg / L, respectively. The roughening treatment temperature was 28℃, and the roughening treatment current density was 30 A / dm³. 2 The roughening treatment electroplating time is 20 s; the curing treatment electroplating solution includes Cu 2+ The concentrations were 50 g / L and H2SO4 concentration was 100 g / L, the curing temperature was 55℃, and the curing current density was 30 A / dm³. 2The electroplating time for curing was 20 seconds. NiP resistive material was electroplated onto the rough surface to achieve a sheet resistance of 50 Ω / □ and a resistance uniformity of 2.5%. Anti-oxidation layers were then prepared on both the smooth and rough surfaces using electroplating, with a nickel content of 20 mg / m². 2 The zinc content is 30 mg / m³. 2 The chromium content is 5 mg / m³. 2 Finally, a 1 nm thick layer of 3-aminopropyltriethoxysilane is coated onto the textured surface.

[0089] Example 4

[0090] A roughening treatment was performed on a green foil with a thickness of 35 μm, a surface roughness Rz of 10.0 μm, and a surface roughness Rz of 2.0 μm. Copper nodule electroplating was then used to achieve a surface roughness Rz of 15.0 μm for both the surface and the surface after electroplating. The copper nodule electroplating process included sequential roughening and curing treatments. The roughening treatment electroplating solution included Cu... 2+ The concentrations of H₂SO₄, tungsten ions, and H₂SO₄ were 15 g / L and 120 g / L respectively. The roughening treatment temperature was 22℃ and the roughening treatment current density was 20 A / dm². 2 The roughening treatment electroplating time is 30 s; the curing treatment electroplating solution includes Cu 2+ The concentrations of H2SO4 and H2SO4 were 40 g / L and 90 g / L, respectively. The curing temperature was 45℃ and the curing current density was 20 A / dm³. 2 The electroplating time for curing was 30 s. NiCr resistive material was then deposited using physical vapor deposition on the rough surface, achieving a sheet resistance of 10 Ω / □ and a resistance uniformity of 3.1%. Anti-oxidation layers, with a molybdenum content of 100 mg / m³, were then prepared on both the smooth and rough surfaces using physical vapor deposition. 2 The chromium content is 10 mg / m³. 2 Finally, a 50 nm thick layer of 3-methacryloyloxypropyltrimethoxysilane is coated onto the textured surface.

[0091] Comparative Example 1

[0092] A roughening treatment was performed on the rough surface of a 9 μm thick raw foil with a surface roughness Rz of 0.2 μm and a smooth surface roughness Rz of 0.2 μm. Reverse etching was used to reduce the rough surface roughness Rz to 1.0 μm after etching. The reverse etching conditions were: 60 g / L dilute sulfuric acid solution, 50℃, and 15 s etching time. Chemical vapor deposition of CrSiO resistive material was then performed on the rough surface to achieve a sheet resistance of 200 Ω / □ and a resistance uniformity of 4.7%. Anti-oxidation layers with a cobalt content of 200 mg / m² were then prepared on both the smooth and rough surfaces using chemical vapor deposition. 2 The indium content is 5 mg / m 2 Finally, a 0.1 nm thick layer of 3-(2,3-epoxypropoxy)propyltrimethoxysilane is coated onto the rough surface.

[0093] Comparative Example 2

[0094] A roughening treatment was performed on the rough surface of a 12 μm thick raw foil with a surface roughness Rz of 2.0 μm and a smooth surface roughness Rz of 0.9 μm. Reverse etching was then used to reduce the rough surface roughness Rz to 4.0 μm. The reverse etching conditions were: 100 g / L dilute sulfuric acid solution, 30℃, and 10 s etching time. NiP resistive material was then electrolessly plated onto the rough surface to achieve a sheet resistance of 25 Ω / □ and a resistance uniformity of 2.2%. An anti-oxidation layer with a zinc content of 80 mg / m³ was then prepared on both the smooth and rough surfaces using electroless plating. 2 Finally, a 20 nm thick layer of 3-mercaptopropyltrimethoxysilane is coated onto the textured surface.

[0095] Comparative Example 3

[0096] A roughening treatment was performed on the rough surface of a raw foil with a thickness of 18 μm, a surface roughness Rz of 4.0 μm, and a smooth surface roughness Rz of 1.2 μm. Copper nodule electroplating was then used to reduce the surface roughness Rz to 6.0 μm after electroplating. The copper nodule electroplating process included sequential roughening and curing treatments. The roughening treatment electroplating solution included Cu... 2+ The concentrations of H₂SO₄ and tungsten ions were 20 g / L, 140 g / L, and 20 mg / L, respectively. The roughening treatment temperature was 28℃, and the roughening treatment current density was 30 A / dm³. 2 The roughening treatment electroplating time is 20 s; the curing treatment electroplating solution includes Cu 2+ The concentrations were 50 g / L and H2SO4 concentration was 100 g / L, the curing temperature was 55℃, and the curing current density was 30 A / dm³. 2The electroplating time for curing was 20 seconds. NiP resistive material was electroplated onto the rough surface to achieve a sheet resistance of 50 Ω / □ and a resistance uniformity of 2.5%. Anti-oxidation layers were then prepared on both the smooth and rough surfaces using electroplating, with a nickel content of 20 mg / m². 2 The zinc content is 30 mg / m³. 2 The chromium content is 5 mg / m2. Finally, a 1 nm thick layer of 3-aminopropyltriethoxysilane is coated onto the rough surface.

[0097] Comparative Example 4

[0098] A roughening treatment was performed on the rough surface of a raw foil with a thickness of 35 μm, a surface roughness Rz of 10.0 μm, and a smooth surface roughness Rz of 2.0 μm. The surface roughness Rz was then reduced to 15.0 μm by electroplating copper nodules. The copper nodule electroplating process included sequential roughening and curing treatments. The roughening treatment electroplating solution contained Cu... 2+ The concentrations of H₂SO₄, tungsten ions, and H₂SO₄ were 15 g / L and 120 g / L respectively. The roughening treatment temperature was 22℃ and the roughening treatment current density was 20 A / dm². 2 The roughening treatment electroplating time is 30 s; the curing treatment electroplating solution includes Cu 2+ The concentrations of H2SO4 and H2SO4 were 40 g / L and 90 g / L, respectively. The curing temperature was 45℃ and the curing current density was 20 A / dm³. 2 The electroplating time for curing was 30 s. NiCr resistive material was then deposited using physical vapor deposition on the rough surface, achieving a sheet resistance of 10 Ω / □ and a resistance uniformity of 3.2%. Anti-oxidation layers, with a molybdenum content of 100 mg / m³, were then prepared on both the smooth and rough surfaces using physical vapor deposition. 2 The chromium content is 10 mg / m³. 2 Finally, a 50 nm thick layer of 3-methacryloyloxypropyltrimethoxysilane is coated onto the textured surface.

[0099] All samples were processed and tested. Before laminating the prepreg, two options were selected: browning treatment and no browning treatment. The presence of detachment and bubbling between the copper foil and the prepreg was observed, and the resistance consistency of the final product was tested. Detailed test results are shown in Table 1.

[0100] Among them, the prepreg model is: Shengyi S1000-2M;

[0101] Lamination conditions: pressure 350 PSI, temperature 185℃, time 90 min;

[0102] Bonding strength test standard: IPC-TM-650 2.4.8.

[0103] The resistance consistency test is conducted by taking 5 points on the finished circuit board after processing. These points include the top left, bottom left, top right, bottom right, and center. The resistance consistency is calculated as (maximum measured value - theoretical value) / theoretical value or (theoretical value - minimum measured value) / theoretical value, and the maximum value is taken.

[0104] The specific steps of browning treatment:

[0105] 1. Pretreatment: Remove impurities from the copper foil surface and activate the copper surface.

[0106] The purpose is to remove contaminants such as oil, oxide layer, and fingerprints from the surface of copper foil, and at the same time, to form a micro-rough surface through micro-etching, so as to provide a uniform reaction substrate for the subsequent browning reaction.

[0107] Degreasing: Function: Removes grease, flux residue, and other organic contaminants from the surface of copper foil. Chemicals: Typically, alkaline degreasing agents (such as sodium hydroxide and sodium carbonate combined with surfactants) are used. Conditions: Temperature 50℃, time 1.5 minutes, spray method (spraying provides a more uniform effect).

[0108] Water washing: The purpose is to rinse away any residual degreasing agent to prevent it from being carried into the next process. Conditions: Rinse with room temperature tap water for 35 seconds to ensure no agent residue remains.

[0109] Micro-etching: Its function is to remove the oxide layer on the surface of copper foil by slight etching and form a micro-uneven structure, which increases the adhesion of the subsequent brown coating film.

[0110] Chemicals: 100g / L sulfuric acid, 10g / L hydrogen peroxide. Conditions: Temperature: room temperature (25℃), avoid high temperature to prevent hydrogen peroxide decomposition; Time: 45 seconds; Micro-etching amount: controlled at 1 μm (excessive amount will result in copper foil that is too thin, insufficient amount will result in excessively low roughness).

[0111] Secondary water rinse: This step removes residual acid and copper ions from the micro-etching process, preventing contamination of the browning solution. Conditions: Rinse with room temperature pure water for 1 minute.

[0112] 2. Browning reaction: Formation of organometallic conversion film.

[0113] Composition of browning solution: oxidant Na2S2O8 100 g / L, organic acid: aminosulfonic acid 2 g / L, inhibitor: benzotriazole 8 g / L.

[0114] Reaction conditions: Temperature: 35℃ (too low a temperature results in a slow reaction and a thinner film; too high a temperature results in a violent reaction and easy film peeling); Time: 1.5 minutes (adjusted according to the required film thickness, which needs to be controlled by online monitoring); Spray pressure: 0.1 MPa (to ensure full contact between the browning solution and the copper foil surface, resulting in a uniform film).

[0115] 3. Post-treatment: Fix the film layer and remove residual chemicals.

[0116] Water washing: The purpose is to rinse away any residual browning solution, terminate the reaction, and prevent the membrane from continuing to grow or dissolve. Conditions: Rinse with room temperature pure water for 2 minutes to ensure no chemical residue remains (this can be tested with pH paper; the solution should be neutral).

[0117] Drying: Purpose: To remove surface moisture and prevent the film from failing after being soaked in water (brown films are easily hydrolyzed when exposed to water). Conditions: Hot air drying, temperature 100℃, time 1 minute (too high a temperature will cause the film to age and become brittle, while too low a temperature will result in incomplete drying).

[0118] Table 1. Test Results of Copper Foil Processing

[0119]

[0120] A comparison of Example 1 with Comparative Example 1, Example 2 with Comparative Example 2, Example 3 with Comparative Example 3, and Example 4 with Comparative Example 4 reveals that roughening the originally smooth surface of the copper foil can replace the browning process before laminating the prepreg in downstream PCB manufacturing. Furthermore, the resistance consistency of the final product can be reduced to below 7%, with optimal results below 4%. This reduces PCB processing costs, improves yield, and decreases scrap.

[0121] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An embedded copper foil without browning treatment, characterized in that, include: raw foil; The green foil includes two surfaces, namely surface A and surface B opposite to surface A; The A-side is sequentially provided with a first roughening layer, a resistive material layer, a first anti-oxidation layer, and a silane layer; The B-side is sequentially provided with a second roughening layer and a second anti-oxidation layer; The surface roughness Rz of the first roughening layer and the second roughening layer is 1~15 micrometers.

2. The embedded copper foil according to claim 1, characterized in that, The first roughening layer and the second roughening layer are each formed independently by electroplating copper nodules or reverse etching on the surface of the green foil.

3. The embedded copper foil according to claim 2, characterized in that, The first roughening layer is formed by electroplating copper nodules on the A side of the green foil, wherein the surface roughness Rz of the A side of the green foil is 0.2~10 micrometers; And / or, the second roughening layer is formed by electroplating copper nodules onto the B side of the green foil, wherein the surface roughness Rz of the B side of the green foil is 0.2 to 2 micrometers.

4. The embedded copper foil according to claim 2, characterized in that, The electroplating copper nodule includes a roughening treatment and a curing treatment; the electroplating solution for the roughening treatment includes: 10~30 g / L copper ions, 100~150 g / L sulfuric acid and 5~25 mg / L tungsten ions; The electroplating solution used for the curing process contains 30-60 g / L copper ions and 80-120 g / L sulfuric acid.

5. The embedded copper foil according to claim 4, characterized in that, The roughening treatment temperature is 20℃~40℃; the roughening treatment current density is 10~30 A / dm. 2 ; The roughening process takes 5-30 seconds. The curing temperature is 40℃~60℃; The current density of the curing process is 10~30 A / dm. 2 ; The curing process takes 5 to 30 seconds.

6. The embedded copper foil according to claim 2, characterized in that, The etching solution for the reverse etching is a dilute sulfuric acid solution of 20~100 g / L; The temperature for the reverse etching is 30℃~60℃; The reverse etching time is 5~15s.

7. The embedded copper foil according to claim 1, characterized in that, The sheet resistance of the resistive material layer is 10~200Ω / □.

8. The embedded copper foil according to claim 1, characterized in that, The first and second anti-oxidation layers each independently comprise one or more of nickel, cobalt, zinc, molybdenum, indium, and chromium; the content of one or more of nickel, cobalt, zinc, molybdenum, indium, and chromium in the first and second anti-oxidation layers each independently ranges from 1 to 500 mg / m³. 2 .

9. The embedded copper foil according to claim 1, characterized in that, The thickness of the silane layer is 0.1~80nm.

10. The embedded copper foil according to claim 1, characterized in that, The silane layer includes one or more of epoxy silanes, amino silanes, mercapto silanes, vinyl silanes, ureosilanes, acrylic silanes, and fluorinated silanes.

Images