Roughening liquid for electrolytic copper foil composite coarsening layer and preparation and use method of coarsening liquid

Abstract

The invention discloses a coarsening solution for an electrolytic copper foil composite coarsening layer and a preparation and use method thereof, and belongs to the technical field of electrolytic copper foil surface treatment. The preparation method comprises the following steps: adding high-conductivity / heat-conductivity nano solid powder (such as carbon powder, graphene and the like with the concentration of 10-1000mg / L) subjected to strong acid activation and surfactant functionalization treatment into a copper sulfate-sulfuric acid base solution, and embedding the powder into a coarsening layer by utilizing a co-deposition electroplating process. According to the method, a composite structure with uniform morphology can be formed without an additive, the functional limitation of a traditional pure copper coarsening layer is broken through, the electrical conductivity and the thermal conductivity are remarkably improved while the low roughness of the copper foil is maintained, and the bottleneck problems of high-frequency signal integrity attenuation and heat dissipation in the field of 5G communication equipment and servers are effectively solved.

Description

Technical Field

[0001] This invention belongs to the field of electrolytic copper foil surface treatment technology, specifically relating to a roughening liquid for an electrolytic copper foil composite roughening layer and its preparation and application method. Background Technology

[0002] With the rapid development of 5G communication, high-speed servers, and artificial intelligence hardware, higher requirements are being placed on the signal transmission integrity of printed circuit boards (PCBs). As a core conductive material, the surface roughness (Rz) of electrolytic copper foil has become a key factor affecting the skin effect loss of high-frequency signals. Traditional DC electroplating roughening processes enhance the adhesion to the resin substrate by depositing micron-sized copper nodules (size 1~2.5μm, Rz>2.5μm) on the copper foil surface, but this leads to a significant increase in transmission loss for high-frequency signals (>10GHz). To reduce losses, the industry has developed low profile (LP) and ultra-low profile (HVLP) copper foils, which effectively improve signal integrity by reducing the copper nodule size (Rz<1.5μm). However, the reduction in roughness inevitably reduces the physical anchoring contact area between the copper nodule and the resin, resulting in a significant decrease in interfacial peel strength (especially under high-temperature conditions), making it difficult to meet the reliability requirements of multilayer board lamination (180~200℃) and lead-free reflow soldering (peak 260℃). While existing additives (such as natural polysaccharides and rare earth salts) or graded electroplating processes can refine grains to a certain extent, they face bottlenecks in improving high-temperature adhesion while maintaining ultra-low roughness.

[0003] In high-frequency, high-speed circuit applications, the signal transmission path primarily resides within the roughening layer. Traditional roughening layers, formed by DC electroplating to create pure copper nodule-like protrusions (Cu purity > 99.9%), while improving mechanical bonding with resin, suffer from inherent electrical performance defects. Firstly, the pure copper roughening layer forms a polycrystalline structure during deposition, with a grain boundary density significantly higher than the substrate copper foil. When high-frequency current (> 10 GHz) flows through it, the resistivity increases by 30%–50% due to grain boundary scattering and surface oxide impedance compared to dense copper foil. Experimental measurements show that conductor loss in the traditional roughening layer accounts for over 65% of total signal loss in the 28 GHz band, severely limiting transmission efficiency. Furthermore, the micro-voids between the copper nodules obstruct heat conduction paths, reducing the thermal conductivity of the roughening layer. Under high current density operating environments (such as AI servers), this leads to localized temperature rise, accelerating interface aging and inducing signal distortion.

[0004] Given the shortcomings of existing copper foil roughening technology, we consider embedding highly conductive nanopowder materials such as graphene and carbon powder into the roughening layer to form a composite roughening layer. By utilizing the high electrical and thermal conductivity of graphene and carbon powder, we can enhance the conductivity and heat dissipation of the roughening layer. Summary of the Invention

[0005] The present application aims to solve the problem that the conventional roughening layer is difficult to meet the low loss and high heat dissipation of 5G signal transmission, and provides a roughening solution for an electrolytic copper foil composite roughening layer and a preparation and use method thereof.

[0006] To achieve the above-mentioned purpose, the technical solutions adopted by the present application are as follows:

[0007] A roughening solution for an electrolytic copper foil composite roughening layer, the roughening solution comprising 50-80 g / L copper sulfate, 100-150 g / L sulfuric acid, 10-1000 mg / L nano solid powder and deionized water as a solvent.

[0008] Further, the nano solid powder is one or more of carbon powder, graphene, graphene oxide, activated carbon, carbon black, acetylene black or carbon nanotubes.

[0009] Further, the nano solid powder is activated by a strong acid and treated by a surfactant.

[0010] Further, the strong acid is sulfuric acid and / or nitric acid.

[0011] Further, the surfactant is one or more of sodium dodecyl benzene sulfonate (SDBS), sodium dodecyl sulfate (SDS), cetyltrimethylammonium bromide, polyoxypropylene polyoxyethylene copolymer and polyacrylic acid.

[0012] A preparation method of the above-mentioned roughening solution for an electrolytic copper foil composite roughening layer, the method comprising the following steps:

[0013] (1) Nano solid powder activation: put the nano solid powder into a strong acid, stir at 50-70 DEG C for 0.5-5 h, and then wash the excess acid with deionized water;

[0014] (2) Nano solid powder surface functionalization: add the nano solid powder obtained in step (1) to a 10-100 g / L surfactant aqueous solution, stir at 60-80 DEG C for 2-24 h, and then perform solid-liquid separation by using a centrifuge;

[0015] (3) Mix the nano solid powder obtained in step (2) with other components in deionized water to obtain the roughening solution.

[0016] A use method of the above-mentioned roughening solution for an electrolytic copper foil composite roughening layer, the method being:

[0017] (1) Copper foil oil removal: immerse the copper foil to be roughened in the oil removal solution for oil removal;

[0018] (2) Copper foil pickling: immerse the cleaned copper foil in step (1) in the pickling solution for pickling;

[0019] (3) Copper foil roughening; the roughening liquid is heated to 25-40°C, an iridium titanium mesh is used as an anode, and the copper foil washed in step (2) is used as a cathode to perform electroplating, the current density is 15-25 A / dm 2 , the power-on time is 6-15 s;

[0020] (4) Copper foil solidification: the electrolytic copper foil in step (3) is placed in a solidification liquid to perform electroplating, the solidification liquid temperature is 30-40°C, the current density is 20-30 A / dm 2 , the power-on time is 10-20 s;

[0021] (5) Copper foil oxidation resistance: the copper foil obtained in step (4) is placed in an oxidation resistance liquid for 20-120 s;

[0022] (6) Copper foil drying: the copper foil washed in step (5) is dried at 50-150°C.

[0023] Further, in step (1), the oil removal liquid is prepared from oil removal powder, the oil removal powder concentration is 30-50 g / L; the oil removal temperature is 40-60°C, and the time is 30-180 s.

[0024] Further, in step (2), the composition of the pickling liquid includes 40-60 g / L copper sulfate, 150-200 g / L sulfuric acid, and a proper amount of deionized water; the pickling temperature is 20-35°C, and the time is 5-60 s.

[0025] Further, in step (4), the composition of the solidification liquid includes 120-240 g / L copper sulfate, 110-150 g / L sulfuric acid, and a proper amount of deionized water; in step (5), the composition of the oxidation resistance liquid includes 0.5-5 g / L benzotriazole and a proper amount of deionized water.

[0026] The beneficial effects of the present application relative to the prior art are: the present application can successfully prepare a roughening layer particle with uniform morphology under the condition of no additive. This technology can reduce the surface roughness of the copper foil while ensuring that the peeling strength maintains a high level. Unlike the existing roughening layer of pure copper structure, the present application embeds solid powder particles in the roughening layer through co-deposition, thereby significantly improving the electrical conductivity and thermal conductivity. In addition, thanks to the diversity of the types of solid powder, the prepared composite roughening layer can be further expanded to other functional roughening layers. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 SEM image of 5k times of the copper foil after roughening treatment in Example 1;

[0028] Figure 2 SEM and EDS images of 10k times of the copper foil after roughening treatment in Example 1;

[0029] Figure 3 SEM image of Example 2 copper foil after roughening treatment at 5k times;

[0030] Figure 4 SEM and EDS images of Example 2 copper foil after roughening treatment at 10k times;

[0031] Figure 5 SEM image of Comparative Example 1 copper foil after roughening treatment at 5k times;

[0032] Figure 6 SEM image of Comparative Example 2 copper foil after roughening treatment at 5k times. DETAILED DESCRIPTION

[0033] For the purpose of illustrating the present application, the technical solutions and advantages thereof, reference will be made to the following embodiments. It is to be noted that the following examples are intended to be illustrative only and not limiting to the scope of the present application. Any modification or equivalent arrangement within the spirit of the present application shall be encompassed within the scope of the present application.

[0034] Example 1:

[0035] A method for preparing a roughening solution for a composite roughening layer of an electrolytic copper foil, comprising the following steps:

[0036] (1) Activate the nano-carbon powder by adding it to excess sulfuric acid, stirring at 50°C for 2h, and then washing the excess acid with deionized water.

[0037] (2) Add the activated nano-carbon powder to a 50g / L aqueous solution of sodium dodecyl sulfate, stir at 60°C for 2h, and then dry after solid-liquid separation using a centrifuge.

[0038] (3) Add the dried nano-carbon powder to a base solution containing 60g / L copper sulfate and 100g / L sulfuric acid, with a nano-carbon powder concentration of 50mg / L, to obtain a roughening solution for preparing a composite roughening layer.

[0039] A process for preparing a composite roughening layer of a copper foil, using the above-mentioned roughening solution, comprising the following steps:

[0040] (1) Place the copper foil to be roughened in a 40g / L oil removal solution and soak at 40°C for 30s.

[0041] (2) Immerse the oil-removed copper foil in an acid pickling solution containing 40g / L copper sulfate and 150g / L sulfuric acid for 10s, with the acid pickling solution temperature being 25°C.

[0042] (3) Heat the roughening solution prepared above to 30°C, and perform electroplating with an iridium-titanium mesh as the anode and the acid-pickled copper foil as the cathode, with a current density of 15A / dm 2 , and a power-on time of 8s.

[0043] (4) The roughened copper foil is placed in a solidification solution containing 130 g / L copper sulfate and 120 g / L sulfuric acid for electroplating, the temperature of the solidification solution is 30°C, the current density is 20 A / dm 2 , and the power-on time is 10 s.

[0044] (5) The cleaned copper foil in step (4) is placed in a solution of 1 g / L benzotriazole for 30 s.

[0045] (6) The copper foil is dried at 60°C.

[0046] The SEM image of the composite roughening layer obtained in this example is shown in Figure 1 , the surface of the prepared composite roughening layer is uniform and dense, and the roughness is only 1.05 µm, which is mainly due to the fact that the carbon powder provides a large number of active sites for copper ion nucleation. The composition of the composite roughening layer is shown in Figure 2 , and the presence of carbon in the composite roughening layer is obviously observed.

[0047] Example 2

[0048] A method for preparing a roughening solution for a composite roughening layer of an electrolytic copper foil, comprising the following steps:

[0049] (1) Nano-carbon powder is added to an excess of nitric acid for activation, stirred at 70°C for 1 h, and then washed with deionized water to remove excess acid.

[0050] (2) The activated nano-carbon powder is added to a solution of 50 g / L sodium dodecyl benzene sulfonate, stirred at 50°C for 3 h, and then dried after solid-liquid separation by a centrifuge.

[0051] (3) The dried nano-carbon powder is added to a base solution containing 70 g / L copper sulfate and 120 g / L sulfuric acid, and the concentration of the nano-carbon powder is 100 mg / L, to obtain a roughening solution for preparing a composite roughening layer.

[0052] A process for preparing a composite roughening layer of a copper foil, using the above-mentioned roughening solution, comprising the following steps:

[0053] (1) The copper foil to be roughened is placed in a 45 g / L oil removal solution and soaked at 50°C for 1 min.

[0054] (2) The copper foil after oil removal is immersed in an acid pickling solution containing 50 g / L copper sulfate and 150 g / L sulfuric acid for 10 s, and the temperature of the acid pickling solution is 30°C.

[0055] (3) The roughening solution prepared above is heated to 30°C, and the copper foil after acid pickling is used as the cathode for electroplating with an iridium-titanium mesh as the anode, the current density is 20 A / dm 2 , and the power-on time is 8 s.

[0056] (4) The roughened copper foil is placed in a curing solution containing 140 g / L copper sulfate and 120 g / L sulfuric acid for electroplating. The curing solution temperature is 35℃ and the current density is 25 A / dm³. 2 Power-on time is 15 seconds.

[0057] (5) Place the cleaned copper foil from step (4) into a 1.5 g / L benzotriazole solution for 1 min.

[0058] (6) Dry the copper foil at 100°C.

[0059] The SEM image of the composite coarsening layer obtained in this embodiment is as follows: Figure 3 As shown, the composite roughening layer has dense, irregularly sized particles with a roughness of 1.42 µm. The large current and long deposition time caused some grains to overgrow, forming larger particles and increasing the roughness. Figure 4 EDS analysis confirmed the presence of carbon powder in the composite roughening layer.

[0060] Comparative Example 1

[0061] In Comparative Example 1, the steps were exactly the same as in Example 1, except that nano-carbon powder was not added to the roughening solution. Figure 5 It can be seen that the roughened layer has sparse particles and particle agglomeration, with a relatively large roughness of 1.83µm.

[0062] Comparative Example 2

[0063] In Comparative Example 2, the steps were exactly the same as in Example 2, except that nano-carbon powder was not added to the roughening solution. Figure 6 It can be seen that the particle morphology and size of the roughened layer vary greatly, with many particles agglomerating to form larger particles, and the roughness is 2.32µm.

[0064] Furthermore, it should be clarified that although this specification describes different embodiments, each embodiment does not necessarily contain only a single technical solution. The description in this specification is for clarity only, and those skilled in the art should understand the specification as a whole. The technical solutions in each embodiment can also be reasonably combined to form other embodiments that those skilled in the art can foresee.

Claims

1. A roughening solution for roughening a composite roughening layer of an electrolytic copper foil, characterized by: The roughening solution comprises 50-80 g / L copper sulfate, 100-150 g / L sulfuric acid, and 10-1000 mg / L nano-solid powder.

2. The roughing liquid according to claim 1, characterized by: The nano-solid powder is one or more of carbon powder, graphene, graphene oxide, activated carbon, carbon black, acetylene black, or carbon nanotube.

3. The roughing solution according to claim 1 or 2, characterized in that: The nano-solid powder is activated by strong acid and treated by surfactant.

4. The roughing liquid according to claim 3, characterized by: The strong acid is sulfuric acid and / or nitric acid.

5. The roughing solution according to claim 3, characterized in that: The surfactant is one or more of sodium dodecyl benzene sulfonate (SDBS), sodium dodecyl sulfate (SDS), cetyltrimethylammonium bromide, polyoxypropylene polyoxyethylene copolymer, and polyacrylic acid.

6. A method for preparing a roughening solution for the roughening layer of the electrolytic copper foil composite roughening layer according to any one of claims 1 to 5, characterized by: The method comprises the following steps: (1) Nano-solid powder activation: put the nano-solid powder into strong acid, stir at 50-70°C for 0.5-5 h, and then wash the excess acid with deionized water; (2) Nano-solid powder surface functionalization: add the nano-solid powder obtained in step (1) to a 10-100 g / L surfactant aqueous solution, stir at 60-80°C for 2-24 h, and then perform solid-liquid separation using a centrifuge; (3) Mix the nano-solid powder obtained in step (2) with other components in deionized water to obtain a roughening solution.

7. A method of using the roughening solution for the roughened layer of the electrolytic copper foil composite according to any one of claims 1 to 5, characterized by: The method is: (1) Copper foil oil removal: immerse the copper foil to be roughened in an oil removal solution to remove oil; (2) Copper foil pickling: immerse the cleaned copper foil in step (1) in a pickling solution for pickling; (3) roughening of copper foil; the roughening solution is heated to 25-40°C, and the copper foil washed in step (2) is used as the cathode and an iridium-titanium mesh is used as the anode to perform electroplating at a current density of 15-25 A / dm 2 , and the power-on time is 6-15 s; (4) Copper foil solidification: the electrolytic copper foil in step (3) is placed in a solidification liquid for electroplating, the solidification liquid temperature is 30-40°C, the current density is 20-30 A / dm 2 , the power-on time is 10-20 s; (5) Copper foil solidification: the electrolytic copper foil in step (4) is placed in a solidification liquid for electroplating, the solidification liquid temperature is 30-40°C, the current density is 20-30 A / dm 2 , the power-on time is 10-20 (5) Copper foil oxidation resistance: place the copper foil obtained in step (4) in an oxidation resistance solution for 20-120 s; (6) Copper foil drying: dry the cleaned copper foil in step (5) at 50-150°C.

8. The method of claim 7, wherein: In step (1), the oil removal solution is prepared from oil removal powder with a concentration of 30-50 g / L; the oil removal temperature is 40-60°C, and the time is 30-180 s.

9. The method of claim 7, wherein: In step (2), the components of the pickling solution include 40-60 g / L copper sulfate and 150-200 g / L sulfuric acid; the pickling temperature is 20-35°C, and the time is 5-60 s.

10. The method of claim 7, wherein: In step (4), the components of the solidification solution include 120-240 g / L copper sulfate and 110-150 g / L sulfuric acid; in step (5), the components of the oxidation resistance solution include 0.5-5 g / L benzotriazole.

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