Large-scale preparation method of ultrathin foamy copper

Abstract

The invention belongs to the technical field of foam metal preparation, and particularly relates to a large-scale preparation method of ultrathin foam copper. According to the preparation method, polyurethane foam serves as a base material, and the ultrathin foamy copper finished product is obtained through the following steps of oil removal, coarsening, palladium activation, reduction, chemical copper plating, copper electroplating and heat treatment. The palladium activation adopts an alkaline ion palladium activation solution for treatment, and the alkaline ion palladium activation solution comprises the following components: palladium chloride, ammonium chloride, organic amine and water; the pH value of the alkaline ion palladium activation solution is 9-11, and the pH value is adjusted by sodium hydroxide. According to the method, the ultrathin polyurethane foam is adopted as a matrix, an innovative alkaline ion palladium activation process is adopted in the chemical plating process, sensitization and dispergation steps are not needed, the obtained ultrathin foam copper finished product is uniform in pore and plating layer, the technological process is simple, the cost is low, and the method is suitable for large-scale production of the ultrathin foam copper.

Description

Technical Field

[0001] The invention belongs to the technical field of foam metal preparation, and in particular relates to a large-scale preparation method of ultra-thin foam copper. Background Art

[0002] Metal foams, with their unique porous structure, offer significant advantages such as light weight, high strength, large surface area, and excellent sound absorption and thermal insulation properties. They have shown broad application potential in a variety of fields, including aerospace, automotive, construction, and energy storage. Currently, metal foam preparation methods primarily include casting, foaming, electrodeposition, vapor deposition, and powder sintering. Future development directions for metal foams focus on reducing manufacturing costs, increasing foam porosity, and reducing pore size.

[0003] Copper foam, one of the most important metal foams, boasts excellent electrical and thermal conductivity and is primarily used as anode carriers for batteries, catalyst supports, and as thermal and energy storage materials. Currently, the primary method for preparing commercial copper foam is electrodeposition using a foam plastic substrate. However, this method still presents challenges such as a thick copper foam substrate, complex preparation processes, and high costs, hindering its effective application as an electrode material. Conventional plastic electroplating typically utilizes colloidal palladium activation, a process that presents drawbacks such as complex steps and poor stability. Ionic palladium activation, on the other hand, has simpler steps, a longer lifespan, and is more suitable for large-scale production.

[0004] Chinese patent CN104087975A discloses a preparation method of a copper foam, which is subjected to chemical copper plating and electroplating thickening after treatments such as twice roughening, sensitization, activation and degumming, and finally obtains copper foam by thermal treatment. Its disadvantage is that the surface treatment process before the chemical copper plating is complicated, and multiple roughenings easily cause thinner polyurethane substrates to break, and it is impossible to obtain thinner copper foam by this treatment process. Chinese patent CN108193234A discloses a preparation method of a durable copper foam, which is subjected to chemical copper plating after sensitization, degumming and activation by the polyurethane foam after roughening, and finally obtains copper foam by thermal treatment. The disadvantage of this process is that the surface treatment steps are more, and the conditions are complex, and the reaction time is long, which is not suitable for requiring low-cost, high-efficiency large-scale production. Therefore, it is necessary to develop a copper foam process with a simple technical process and bright and uniform coating to achieve the large-scale industrial production of ultra-thin, high-porosity copper foam with this. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A large-scale preparation method for ultra-thin copper foam comprises the following steps: using polyurethane foam as a substrate to obtain an ultra-thin copper foam product through the following steps: degreasing, roughening, palladium activation, reduction, chemical copper plating, electroplating copper, and heat treatment; the palladium activation is performed using an alkaline ion palladium activation solution, and the components of the alkaline ion palladium activation solution include palladium chloride, ammonium chloride, organic amine, and water.

[0007] Furthermore, the large-scale preparation method of the ultra-thin copper foam specifically comprises the following steps:

[0008] S1, degreasing: immersing the polyurethane foam in a degreasing liquid for degreasing and cleaning to obtain a degreasing polyurethane foam;

[0009] S2, roughening: immersing the degreased polyurethane foam in an alkaline roughening solution for roughening and washing to obtain a roughened polyurethane foam;

[0010] S3, palladium activation: immersing the roughened polyurethane foam in the alkaline ion palladium activation solution for palladium activation, and washing to obtain an activated polyurethane foam;

[0011] S4, reduction: immersing the activated polyurethane foam in a reducing solution for reduction, and washing to obtain a reduced polyurethane foam;

[0012] S5, chemical copper plating: immersing the reduced polyurethane foam in a chemical copper plating solution for chemical copper plating, and washing to obtain a chemically plated polyurethane foam;

[0013] S6, electroplating copper: immersing the chemically plated polyurethane foam in an electroplating solution to electroplate copper, and drying to obtain an electroplated copper polyurethane foam;

[0014] S7, heat treatment: placing the electroplated copper polyurethane foam into a heat treatment device, introducing a protective gas for thermal decomposition and reduction, and cooling to obtain the finished ultra-thin copper foam product.

[0015] Furthermore, in step S3, the alkaline ion palladium activation solution includes the following components: palladium chloride with a concentration of 0.01 to 0.2 g / L, ammonium chloride with a concentration of 0.1 to 0.5 g / L, an organic amine with a concentration of 0.05 to 0.3 g / L, and the remainder water; the organic amine includes one or more of ethylenediamine, ethylene glycolamine, hydroxyethylethylenediamine, and phenylethylamine;

[0016] In step S3, the pH value of the alkaline ion palladium activation solution is 9 to 11, and the pH value is adjusted with sodium hydroxide;

[0017] In step S3, the palladium activation temperature is 40 to 60° C., and the palladium activation time is 40 to 60 seconds.

[0018] Furthermore, when the pH value is adjusted as needed, the components of the alkaline ion palladium activation solution also include sodium hydroxide, and the pH value of the alkaline ion palladium activation solution is adjusted by controlling the amount of sodium hydroxide added.

[0019] Further, in step S5, the chemical copper plating solution includes the following components in concentrations: 10-15 g / L copper sulfate, 10-30 g / L potassium sodium tartrate, 5 g / L disodium EDTA, 16-24 ml / L formaldehyde, 8-12 g / L sodium hydroxide, and the balance water;

[0020] In step S5, the temperature of the chemical copper plating is 35-40°C, and the time of the chemical copper plating is 5-10 minutes. In step S5, air stirring is performed during the chemical copper plating process.

[0021] Furthermore, in step S6, the electroplating solution includes the following components in concentrations: 80 g / L copper pyrophosphate, 300-350 g / L potassium pyrophosphate, 10-20 g / L HEDP, 2-5 ppm ammonia water, 2-4 ppm 2-mercaptobenzimidazole, and the balance water;

[0022] In step S6, the temperature of the copper electroplating is 50-60°C; in step S6, the copper electroplating includes the following steps: pre-plating and electrodeposition.

[0023] Furthermore, step S6 specifically includes the following steps:

[0024] S6-A, completely immersing the chemically plated polyurethane foam in the electroplating solution for pre-plating to obtain an electroplated copper intermediate product a; the apparent current density of the pre-plating is 0.5 to 1 A / dm 2 ; The pre-plating time includes 2 to 5 minutes;

[0025] S6-B, further subjecting the electroplated copper intermediate product a to the electroplating to obtain the electroplated copper intermediate product b; wherein the apparent current density of the electroplating is 1 to 5 A / dm 2 ; The electrodeposition time includes 10 to 60 minutes;

[0026] S6-C, drying the electroplated copper intermediate product b to obtain the electroplated copper polyurethane foam;

[0027] The processes of step S6-A and step S6-B implement air stirring.

[0028] Furthermore, in step S1, the degreasing liquid includes the following components: a degreasing agent with a concentration of 10 to 100 ml / L, concentrated sulfuric acid with a concentration of 30 to 400 ml / L, and the balance water; the degreasing agent includes the following ingredients: a complexing agent, an emulsifier, a penetrant, an adsorbent, an oil-in-water surfactant, and water; in step S1, the degreasing temperature includes 40 to 70° C., and the degreasing time includes 30 seconds to 5 minutes;

[0029] In step S2, the roughening liquid includes the following components: a roughening agent with a concentration of 300 to 600 g / L and the balance water; the roughening agent includes the following ingredients in weight percentage: 50% to 80% of an alkaline compound, 1% to 15% of an oxidizing compound, 1% to 10% of a fluoride, 1% to 15% of a complexing agent, and 0.1% to 10% of a surfactant; in step S2, the roughening temperature includes 50 to 80° C., and the roughening time includes 2 to 10 minutes.

[0030] Furthermore, in the roughening agent, the alkaline compound includes one or more of sodium hydroxide, potassium hydroxide and lithium hydroxide;

[0031] In the roughening agent, the oxidizing compound includes one or more of sodium persulfate, potassium persulfate, sodium perborate, potassium perborate, sodium hypochlorite and potassium hypochlorite;

[0032] In the roughening agent, the fluoride includes one or more of sodium fluoride, potassium fluoride, sodium bifluoride, potassium bifluoride, ammonium bifluoride, fluoroborate and ammonium fluoride;

[0033] In the roughening agent, the complexing agent includes one or more of EDTA, citrate, polyethylene polyamines and organic phosphonates;

[0034] In the roughening agent, the surfactant includes one or more of dodecylbenzene sulfonate, dodecyl sulfonate, dodecyl sulfate, dodecylbenzene sulfate, alkyl polyoxyethylene ether, naphthalenesulfonic acid formaldehyde polymer, polyethylene glycol, fatty acid glyceride, fatty acid sorbitan ester and polysorbate.

[0035] Furthermore, before step S7, the copper electroplated polyurethane foam is exposed to air, thereby forming copper oxide on the surface of the copper electroplated polyurethane foam.

[0036] Furthermore, in step S7, the thermal decomposition and reduction include decomposing the base material of the electroplated copper polyurethane foam and reducing copper oxide on the surface of the electroplated copper polyurethane foam.

[0037] Furthermore, in step S4, the reducing solution includes one or more of a sodium hypophosphite aqueous solution or a hydrazine hydrate solution; in step S4, the reducing temperature includes 25 to 35° C., and the reducing time includes 40 to 60 seconds;

[0038] In step S7, the thermal decomposition and reduction specifically include the following steps: heating the electroplated copper polyurethane foam to 500-700° C. and maintaining the temperature for 30-90 minutes, and naturally cooling the foam to room temperature to obtain the ultra-thin copper foam product;

[0039] In step S7, the protective gas includes a mixture of H2 and N2, and the volume fraction of H2 in the protective gas includes 10%; in step S7, the heat treatment equipment includes a roller kiln;

[0040] The cleaning method described in step S1 includes cleaning with deionized water; the cleaning method described in step S2 includes cleaning with deionized water; the cleaning method described in step S3 includes cleaning with deionized water; the cleaning method described in step S4 includes cleaning with deionized water; the cleaning method described in step S5 includes cleaning with deionized water.

[0041] As a preferred solution of the large-scale preparation method of the ultra-thin copper foam of the present invention, the thickness of the polyurethane foam is 0.1 to 10 mm; the porosity of the polyurethane foam is ≥90%; and the pore size of the polyurethane foam is 20 to 500 μm.

[0042] Furthermore, the coating thickness of the ultra-thin copper foam of the present invention is much smaller than the thickness of the polyurethane foam, and thus the thickness of the ultra-thin copper foam is comparable to that of the polyurethane foam.

[0043] Furthermore, in step S1, the deoiling agent includes SF-LCP deoiling agent purchased from Guangzhou Sanfu New Materials Technology Co., Ltd.

[0044] Furthermore, the cleaning method in step S1 includes cleaning with deionized water 2 to 3 times;

[0045] Furthermore, the cleaning method in step S2 includes cleaning with deionized water 2 to 3 times;

[0046] Furthermore, the cleaning method in step S3 includes cleaning with deionized water 2 to 3 times;

[0047] Furthermore, the cleaning method in step S4 includes cleaning with deionized water 1 to 2 times;

[0048] Furthermore, the cleaning method in step S5 includes cleaning with deionized water 1 to 2 times.

[0049] Furthermore, in step S6-C, the drying includes complete drying.

[0050] The principle of ionic palladium activation is as follows: the ionic palladium activation solution is essentially an aqueous solution of a palladium complex. This method usually uses Pd(II) salt as a catalyst. During the reaction, after the palladium complex ions are adsorbed on the substrate surface and reach equilibrium, they are reduced to particles with metal catalytic activity and further undergo addition, oxidation, cross-coupling and other reactions. The ionic palladium activation solution of the present invention can be used for a long time without sedimentation and separation, has a long service life and good stability, and overcomes the problem of a layer of Sn adsorbed on the substrate surface during the colloidal palladium activation process. 2+ This will affect the uniformity and adhesion of the subsequent chemical plating.

[0051] Ionic palladium activation is a catalyst-based reaction. In the present invention, the electrostatic interaction between the H (hydrogen atoms) on the -NH2, -OH and other groups in the complexing agent organic amine and the carbonyl oxygen on the substrate polyurethane is mainly achieved to coordinate palladium to form a catalyst, replacing one or more hydrogen atoms with Pd (II) ions, thereby stimulating the reactivity of other functional groups in the organic molecule.

[0052] Furthermore, the present invention's palladium ion activation is performed under alkaline conditions. The palladium complex in the alkaline palladium ion system is more stable than that in the acidic palladium ion system, which can increase the amount of palladium adsorbed on the polyurethane surface and enhance its bonding with the chemically plated coating. At low pH, the organic amine complex exists as a salt with poor complexing ability. However, as the pH increases, its complexing ability significantly increases, which helps improve activation performance.

[0053] Advantages of the alkaline ion palladium activation solution of the present invention:

[0054] 1. It can activate the reactive properties of functional groups in specific substrates (polyurethane), thereby achieving efficient catalysis;

[0055] 2. It can achieve selective catalysis, that is, only hydrogen atoms at specific positions are replaced and reacted;

[0056] 3. The reaction can be carried out using low palladium amounts and mild conditions, thereby reducing environmental and economic costs;

[0057] 4. A variety of different types of organic substrates can be used for the reaction, including polyurethane (PU) used in the present invention, polyimide (PI) and the like, so it has a wide range of applicability.

[0058] Compared with the prior art, the present invention has the following beneficial effects:

[0059] 1. The present invention uses ultra-thin polyurethane (PU) foam as a matrix and adopts an innovative ion palladium activation process in the chemical plating process. No sensitization and debonding steps are required. The obtained ultra-thin foam copper product has uniform pores and plating layers, a simple process flow, and low cost, and is suitable for large-scale production of ultra-thin foam copper.

[0060] 2. The preparation method of the present invention uses an alkaline ion palladium activation solution. Compared with the acidic ion palladium system, the alkaline ion palladium system of the present invention has a more stable complexing ability with palladium; when the pH is within a certain range, the bonding force between the palladium system of the present invention and the chemical plating layer is stronger, and the final foam copper product obtained has a better coating condition;

[0061] 3. The preparation method of the present invention not only uses an alkaline ion palladium activation solution, but also uses the degreasing solution and alkaline roughening solution of the present invention for pre-plating treatment, and is combined with the electroplating solution and chemical copper plating solution of the present invention for copper plating. The foam copper product finally obtained has a better coating condition.

[0062] 4. The present invention also fills the technical gap in the field of preparation of ultra-thin foam copper (thickness as low as 0.1 mm). BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1 The ultra-thin copper foam product of Example 1;

[0064] Figure 2 This is an SEM image of the finished ultrathin copper foam product of Example 1;

[0065] Figure 3 The ultra-thin foam copper product of Comparative Example 1;

[0066] Figure 4 The ultra-thin foam copper product of Comparative Example 3;

[0067] Figure 5 This is the finished product of ultra-thin copper foam of Comparative Example 9. DETAILED DESCRIPTION

[0068] To make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings. The components and contents of the relevant materials in the following examples are shown in Table 1.

[0069] Table 1

[0070]

[0071]

[0072] Example 1

[0073] The 0.1mm thick polyurethane foam (porosity ≥ 90%, pore size 20-500μm) was placed in a 65℃ degreasing solution for 30s, washed with deionized water three times, and then placed in a 75℃ alkaline roughening solution for 3min. After washing with deionized water three times, it was placed in a 50℃ alkaline ion palladium activation solution for 50s and washed with deionized water twice. Then, it was placed in a 30℃ reducing solution for 45s and washed with deionized water twice, and then placed in a 40℃ chemical copper plating solution for chemical plating for 5min. The foam after deionized water washing was completely immersed in a 55℃ electroplating solution and electroplated at an apparent current density of 0.5A / dm 2 Pre-plating for 2 minutes under the condition of apparent current density of 1A / dm 2 The electroplated copper foam was completely dried to obtain electroplated copper polyurethane foam. Air stirring was implemented during the chemical plating, pre-plating and deposition processes.

[0074] Then, the copper-plated polyurethane foam rolls were placed in a roller kiln, and a mixture of H2 and N2 with a H2 volume fraction of 10% was introduced. The temperature was raised to 575°C and maintained for 40 minutes for thermal decomposition and reduction. The product was naturally cooled to room temperature to obtain an ultra-thin copper foam product. Its appearance and SEM images are shown in Figure 2. Figure 1 and Figure 2 .

[0075] Example 2

[0076] The 0.1mm thick polyurethane foam (porosity ≥ 90%, pore size 20-500μm) was placed in a 65℃ degreasing solution for 1min, washed with deionized water 3 times, and then placed in a 75℃ alkaline roughening solution for 5min. After washing with deionized water 3 times, it was placed in a 50℃ alkaline ion palladium activation solution for 50s and washed with deionized water twice. Then, it was placed in a 30℃ reducing solution for 45s and washed with deionized water twice, and then placed in a 35℃ chemical copper plating solution for chemical plating for 8min. The foam after deionized water washing was completely immersed in a 55℃ electroplating solution and electroplated at an apparent current density of 0.5A / dm 2 Pre-plating for 2 minutes under the condition of apparent current density of 1A / dm 2 The electroplated copper foam was completely dried to obtain electroplated copper polyurethane foam. Air stirring was implemented during the chemical plating, pre-plating and deposition processes.

[0077] The electroplated copper polyurethane foam rolls are then placed into a roller kiln, and a mixture of H2 and N2 with a H2 volume fraction of 10% is introduced. The temperature is raised to 600°C and maintained for 30 minutes for thermal decomposition and reduction, and then naturally cooled to room temperature to obtain an ultra-thin foam copper product.

[0078] Example 3

[0079] The 0.3 mm thick polyurethane foam (porosity ≥ 90%, pore size 20-500 μm) was placed in a 65 ° C degreasing solution for 1 minute, washed with deionized water 3 times, and then placed in a 75 ° C alkaline roughening solution for 5 minutes, washed with deionized water 3 times, and then placed in a 50 ° C alkaline ion palladium activation solution for 50 seconds, and washed with deionized water twice, and then placed in a 30 ° C reducing solution for 45 seconds and washed with deionized water twice, and then placed in a 35 ° C chemical copper plating solution for chemical plating for 8 minutes, and then the foam after deionized water washing was completely immersed in a 55 ° C electroplating solution, and the surface current density was 1A / dm 2 Pre-plating for 3 minutes under the condition of apparent current density of 2A / dm 2 The copper foam was deposited for 40 minutes under the conditions of , and the electroplated copper foam was completely dried to obtain electroplated copper polyurethane foam. Air stirring was implemented during the chemical plating, pre-plating and deposition processes.

[0080] The electroplated copper polyurethane foam rolls are then placed into a roller kiln, and a mixture of H2 and N2 with a H2 volume fraction of 10% is introduced. The temperature is raised to 600°C and maintained for 30 minutes for thermal decomposition and reduction, and then naturally cooled to room temperature to obtain an ultra-thin foam copper product.

[0081] Example 4

[0082] The 0.3 mm thick polyurethane foam (porosity ≥ 90%, pore size 20-500 μm) was placed in a 65 ° C degreasing solution for 1 minute, washed with deionized water 3 times, and then placed in a 75 ° C alkaline roughening solution for 5 minutes, washed with deionized water 3 times, and then placed in a 50 ° C alkaline ion palladium activation solution for 50 seconds, and washed with deionized water twice, and then placed in a 30 ° C reducing solution for 45 seconds and washed with deionized water twice, and then placed in a 35 ° C chemical copper plating solution for chemical plating for 8 minutes, and then the foam after deionized water washing was completely immersed in a 55 ° C electroplating solution, and the surface current density was 1A / dm 2 Pre-plating for 3 minutes under the condition of apparent current density of 2A / dm 2 The electroplated copper foam was completely dried to obtain electroplated copper polyurethane foam. Air stirring was implemented during the chemical plating, pre-plating and deposition processes.

[0083] The electroplated copper polyurethane foam rolls are then placed into a roller kiln, and a mixture of H2 and N2 with a H2 volume fraction of 10% is introduced. The temperature is raised to 600°C and maintained for 30 minutes for thermal decomposition and reduction, and then naturally cooled to room temperature to obtain an ultra-thin foam copper product.

[0084] Example 5

[0085] The 0.6mm thick polyurethane foam (porosity ≥ 90%, pore size 20-500μm) was rolled into a 65℃ degreasing solution for 1 minute, washed with deionized water 3 times, transferred to a 75℃ alkaline roughening solution for 5 minutes, washed with deionized water 3 times, placed in a 50℃ alkaline ion palladium activation solution for 50s, and washed with deionized water twice, then placed in a 30℃ reducing solution for 45s and washed with deionized water twice. It was placed in a 35℃ chemical copper plating solution for chemical plating for 10 minutes, and then the foam after deionized water washing was completely immersed in a 55℃ electroplating solution at an apparent current density of 1A / dm 2 Pre-plating for 2 minutes under the condition of apparent current density of 5A / dm 2 The electroplated copper foam was completely dried to obtain electroplated copper polyurethane foam. Air stirring was implemented during the chemical plating, pre-plating and deposition processes.

[0086] The electroplated copper polyurethane foam rolls are then placed into a roller kiln, and a H2 and N2 mixture with a H2 volume fraction of 10% is introduced. The temperature is raised to 630°C and maintained for 30 minutes for thermal decomposition and reduction, and then naturally cooled to room temperature to obtain an ultra-thin foam copper product.

[0087] Example 6

[0088] The 0.6mm thick polyurethane foam (porosity ≥ 90%, pore size 20-500μm) was rolled into a 65℃ degreasing solution for 1 minute, washed with deionized water 3 times, transferred to a 75℃ alkaline roughening solution for 5 minutes, washed with deionized water 3 times, placed in a 50℃ alkaline ion palladium activation solution for 50s, and washed with deionized water twice, then placed in a 30℃ reducing solution for 45s and washed with deionized water twice. It was placed in a 35℃ chemical copper plating solution for chemical plating for 10 minutes, and then the foam after deionized water washing was completely immersed in a 55℃ electroplating solution at an apparent current density of 1A / dm 2 Pre-plating for 2 minutes under the condition of apparent current density of 5A / dm 2 The electroplated copper foam was completely dried to obtain electroplated copper polyurethane foam. Air stirring was implemented during the chemical plating, pre-plating and deposition processes.

[0089] The electroplated copper polyurethane foam rolls are then placed into a roller kiln, and a H2 and N2 mixture with a H2 volume fraction of 10% is introduced. The temperature is raised to 630°C and maintained for 30 minutes for thermal decomposition and reduction, and then naturally cooled to room temperature to obtain an ultra-thin foam copper product.

[0090] Example 7

[0091] The 3mm thick polyurethane foam (porosity ≥ 90%, pore size 20-500μm) was rolled into a 65℃ degreasing solution for 1 minute, washed with deionized water 3 times, transferred to a 75℃ alkaline roughening solution for 5 minutes, washed with deionized water 3 times, placed in a 50℃ alkaline ion palladium activation solution for 50s, and washed with deionized water twice, then placed in a 30℃ reducing solution for 45s and washed with deionized water twice. It was placed in a 35℃ chemical copper plating solution for chemical plating for 10 minutes, and then the foam after deionized water washing was completely immersed in a 55℃ electroplating solution at an apparent current density of 1A / dm 2 Pre-plating for 2 minutes under the condition of apparent current density of 5A / dm 2 The electroplated copper foam was completely dried to obtain electroplated copper polyurethane foam. Air stirring was implemented during the chemical plating, pre-plating and deposition processes.

[0092] The electroplated copper polyurethane foam rolls are then placed into a roller kiln, and a H2 and N2 mixture with a H2 volume fraction of 10% is introduced. The temperature is raised to 650°C and maintained for 30 minutes for thermal decomposition and reduction, and then naturally cooled to room temperature to obtain an ultra-thin foam copper product.

[0093] Example 8

[0094] The 3mm thick polyurethane foam (porosity ≥ 90%, pore size 20-500μm) was rolled into a 65℃ degreasing solution for 1 minute, washed with deionized water 3 times, transferred to a 75℃ alkaline roughening solution for 5 minutes, washed with deionized water 3 times, placed in a 50℃ alkaline ion palladium activation solution for 50s, and washed with deionized water twice, then placed in a 30℃ reducing solution for 45s and washed with deionized water twice. It was placed in a 35℃ chemical copper plating solution for chemical plating for 10 minutes, and then the foam after deionized water washing was completely immersed in a 55℃ electroplating solution at an apparent current density of 1A / dm 2 Pre-plating for 2 minutes under the condition of apparent current density of 5A / dm 2 The electroplated copper foam was completely dried to obtain electroplated copper polyurethane foam. Air stirring was implemented during the chemical plating, pre-plating and deposition processes.

[0095] The electroplated copper polyurethane foam rolls are then placed into a roller kiln, and a H2 and N2 mixture with a H2 volume fraction of 10% is introduced. The temperature is raised to 650°C and maintained for 30 minutes for thermal decomposition and reduction, and then naturally cooled to room temperature to obtain an ultra-thin foam copper product.

[0096] Example 9

[0097] The 5.0mm thick polyurethane foam (porosity ≥ 90%, pore size 20-500μm) was rolled into a 65℃ degreasing solution for 1 minute, washed with deionized water 3 times, transferred to a 75℃ alkaline roughening solution for 5 minutes, washed with deionized water 3 times, placed in a 50℃ alkaline ion palladium activation solution for 50s, and washed with deionized water twice, then placed in a 30℃ reducing solution for 45s and washed with deionized water twice. It was placed in a 35℃ chemical copper plating solution for chemical plating for 10 minutes, and then the foam after deionized water washing was completely immersed in a 55℃ electroplating solution at an apparent current density of 1A / dm 2 Pre-plating for 2 minutes under the condition of apparent current density of 5A / dm 2 The electroplated copper foam was completely dried to obtain electroplated copper polyurethane foam. Air stirring was implemented during the chemical plating, pre-plating and deposition processes.

[0098] The electroplated copper polyurethane foam rolls are then placed into a roller kiln, and a H2 and N2 mixture with a H2 volume fraction of 10% is introduced. The temperature is raised to 680°C and maintained for 30 minutes for thermal decomposition and reduction, and then naturally cooled to room temperature to obtain an ultra-thin foam copper product.

[0099] Example 10

[0100] The 5.0mm thick polyurethane foam (porosity ≥ 90%, pore size 20-500μm) was rolled into a 65℃ degreasing solution for 1 minute, washed with deionized water 3 times, transferred to a 75℃ alkaline roughening solution for 5 minutes, washed with deionized water 3 times, placed in a 50℃ alkaline ion palladium activation solution for 50s, and washed with deionized water twice, then placed in a 30℃ reducing solution for 45s and washed with deionized water twice. It was placed in a 35℃ chemical copper plating solution for chemical plating for 10 minutes, and then the foam after deionized water washing was completely immersed in a 55℃ electroplating solution at an apparent current density of 1A / dm 2 Pre-plating for 2 minutes under the condition of apparent current density of 5A / dm 2 The electroplated copper foam was completely dried to obtain electroplated copper polyurethane foam. Air stirring was implemented during the chemical plating, pre-plating and deposition processes.

[0101] The electroplated copper polyurethane foam rolls are then placed into a roller kiln, and a H2 and N2 mixture with a H2 volume fraction of 10% is introduced. The temperature is raised to 680°C and maintained for 30 minutes for thermal decomposition and reduction, and then naturally cooled to room temperature to obtain an ultra-thin foam copper product.

[0102] Comparative Example 1

[0103] Ultra-thin copper foam was prepared using the method of Example 1, except that the palladium activation step was replaced by the sensitization-colloidal palladium activation process provided by patent CN104868134B. Specifically, the roughened and cleaned polyurethane foam was placed in a room temperature sensitizing solution (25 g / L stannous chloride, 40 ml / L hydrochloric acid) and soaked for 3 minutes. After the polyurethane foam was cleaned with distilled water, it was placed in a room temperature colloidal palladium activation solution (0.5 g / L palladium chloride, 40 ml / L hydrochloric acid) and activated for 4 minutes. The finished ultra-thin copper foam obtained in Comparative Example 1 is shown in FIG. Figure 3 .

[0104] Comparative Example 2

[0105] Ultrathin copper foam was prepared using the method of Example 1, except that the palladium activation step was replaced by an acidic ion palladium activation process, specifically: activation was performed using an acidic ion palladium activation solution for 5 minutes; the acidic ion palladium activation solution had a formula of: 0.3 g / L palladium chloride, 1 ml / L hydrochloric acid, and 20 g / L boric acid.

[0106] Comparative Example 3

[0107] Ultra-thin copper foam was prepared by the method of Example 3, except that the complexing agent in the electroplating solution was replaced by ammonium citrate instead of HEDP. The finished product of ultra-thin copper foam obtained in Comparative Example 3 is shown in FIG. Figure 4 .

[0108] Comparative Example 4

[0109] Ultrathin copper foam was prepared using the method of Example 3, except that the roughening step was changed to the acidic roughening-reduction process used in patent CN105463417A. Specifically, the specific formula of the roughening solution was: 300 g / L chromium oxide, 100 g / L concentrated sulfuric acid; the roughening temperature was 70°C, and the immersion time was 20 minutes; after being removed from the roughening solution, it was washed with tap water, and the washed polyurethane foam was reduced (10% oxalic acid solution) at a reduction temperature of 30°C and an immersion time of 3 minutes.

[0110] Comparative Example 5

[0111] Ultrathin copper foam was prepared by the method of Example 5, except that the addition amount of the complexing agent (potassium sodium tartrate, disodium EDTA) in the chemical copper plating solution was changed, specifically: 5 g / L potassium sodium tartrate and 45 g / L disodium EDTA.

[0112] Comparative Example 6

[0113] Ultrathin copper foam was prepared using the method of Example 5, except that the palladium activation step was replaced by a silver ammonia solution activation-degumming process, specifically: the roughened polyurethane was cleaned with distilled water and then placed in a sensitizing solution (20 g / L stannous chloride, 40 ml / L hydrochloric acid) at 20°C for 10 min, and then washed with distilled water. The polyurethane foam was then placed in an activation solution (3 g / L silver nitrate, 5 ml / L ammonia solution) at 20°C for activation for 10 min, and the activated polyurethane foam was immersed in a degumming solution (14% hydrochloric acid) for 3 min.

[0114] Comparative Example 7

[0115] Ultra-thin copper foam was prepared by the method of Example 7, except that the formula of the alkaline ion palladium activation solution was changed, specifically, no organic amine was added.

[0116] Comparative Example 8

[0117] Ultrathin copper foam was prepared using the method of Example 7, except that the palladium activation step was changed to the hydrochloric acid washing-other alkaline ion palladium activation-degumming process provided by patent CN105463417A, specifically: the roughened polyurethane foam was washed with hydrochloric acid (30% hydrochloric acid) before activation, the solution temperature was 30°C, and the soaking time was 1 minute; an alkaline ion palladium activation solution (0.02 g / L palladium chloride, 0.04 g / L copper chloride, 1 g / L ammonium chloride, 0.04 g / L 1,10-phenanthroline, 0.04 g / L 4-cyanopyridine) was taken for activation, the activation solution temperature was 25°C, and the activation time was 3 min; after activation, the cleaned polyurethane foam was degummed (10% hydrochloric acid), the solution temperature was 45°C, and the soaking time was 3 minutes.

[0118] Comparative Example 9

[0119] Ultra-thin copper foam was prepared by the method of Example 9, except that the pH of the alkaline ion palladium activation solution was 8. The ultra-thin copper foam product prepared in Comparative Example 9 is shown in FIG. Figure 5 .

[0120] Comparative Example 10

[0121] Ultrathin copper foam was prepared by the method of Example 9, except that the process used in the heat treatment step was changed. Specifically, the electroplated polyurethane foam was placed roll-to-roll in a roller kiln, and a mixed gas of hydrogen and nitrogen with a volume ratio of 3:1 was introduced. The temperature was raised to 400°C at a rate of 2°C / min, and the mixture was kept at this temperature for reduction for 2 hours. The temperature was then continued to be raised to 850°C, kept at this temperature for pyrolysis for 3 hours, and naturally cooled to obtain an ultrathin copper foam product.

[0122] Effect Examples

[0123] The ultra-thin copper foam products of Examples 1-10 and Comparative Examples 1-10 were used as samples to measure their porosity, morphology, and areal density. Porosity was measured using mercury intrusion porosimetry, and areal density was measured using a weighing method. The results are shown in Table 2.

[0124] Table 2

[0125]

[0126] The results in Table 2 are analyzed as follows:

[0127] 1) Examples 1 to 10 adopt the preparation method of the present invention, and the ultra-thin foam copper products obtained have uniform coatings, the porosity of the samples is similar to that of the substrate polyurethane foam (both ≥90%), and the surface density of the foam copper is positively correlated with the deposition time of the copper electroplating step.

[0128] 2) Comparative Examples 1 to 2, Comparative Examples 6 to 9:

[0129] Comparative Example 1 uses a colloidal palladium activation process in the palladium activation step, which requires a sensitization step compared to Example 1, and the coating condition of the ultra-thin foam copper product is poor;

[0130] In the palladium activation step of Comparative Example 2, an acidic ion palladium activation process is used. Compared with Example 2, the coating of the ultra-thin foam copper product is uneven and there are problems such as plating leakage.

[0131] In the palladium activation step of Comparative Example 6, a process of sensitization-silver ammonia solution activation is adopted. Compared with Example 6, sensitization and other steps are required, and the coating of the ultra-thin foam copper product is uneven, and there are problems such as plating leakage.

[0132] Comparative Example 7 changes the formula of the alkaline ion palladium activation solution to not adding organic amine. Compared with Example 7, no plating occurs. The reason for this is that the alkaline ion palladium activation solution lacks a complexing agent, and the palladium ions during palladium activation cannot adhere to the substrate surface at all.

[0133] In the palladium activation step of Comparative Example 8, a process of hydrochloric acid washing-other alkaline ion palladium activation-degumming is adopted. Compared with Example 8, steps such as degumming are required, and the coating of the ultra-thin foam copper product is uneven, and there are problems such as plating leakage.

[0134] In Comparative Example 9, the pH of the alkaline ion palladium activation solution was adjusted to 8. Compared with Example 9, the ultra-thin foam copper product had a small amount of plating leakage.

[0135] In summary, compared with other preparation methods, the preparation method of the present invention, including the alkaline ion palladium activation solution of the present invention and the palladium activation process of the present invention, can significantly improve the quality of the ultra-thin foam copper finished coating, and has fewer steps and a simplified process flow.

[0136] 3) Comparative Examples 3, 4, 5, and 10

[0137] In Comparative Example 3, the complexing agent of the electroplating solution is replaced. Compared with Example 3, the coating of the ultra-thin foam copper product is black, brittle and fragile, and the porosity (92%) is significantly lower than that of Example 3.

[0138] In the roughening step of Comparative Example 4, an acidic roughening-reduction process is adopted. Compared with Example 4, the coating condition of the ultra-thin foam copper product is not good, and there are problems such as plating leakage.

[0139] In Comparative Example 5, the amount of the complexing agent in the chemical copper plating solution was adjusted. Compared with Example 5, a large area of ​​the ultra-thin foam copper product was not plated.

[0140] Comparative Example 10 changes the process used in the heat treatment step. Compared with Example 10, the ultra-thin foam copper product is brittle and fragile.

[0141] In summary, compared with other preparation methods, the quality of the ultra-thin foam copper finished product obtained by the preparation method of the present invention, including the electroplating solution of the present invention, the chemical copper plating solution of the present invention, and the roughening process of the present invention, is significantly improved; the ultra-thin foam copper finished product obtained by the heat treatment process of the present invention can avoid the brittle and fragile texture.

[0142] The above disclosure is merely a preferred embodiment of the present invention and certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. A large-scale preparation method of ultrathin copper foam, characterized in that: The method comprises the following steps of using polyurethane foam as a substrate to obtain an ultra-thin foam copper product: degreasing, roughening, palladium activation, reduction, chemical copper plating, electroplating copper, and heat treatment; the palladium activation adopts alkaline ion palladium activation liquid treatment, and the components of the alkaline ion palladium activation liquid include palladium chloride, ammonium chloride, organic amine, and water.

2. The large-scale preparation method of ultrathin copper foam according to claim 1, characterized in that: The large-scale preparation method of the ultra-thin copper foam specifically comprises the following steps: S1, degreasing: immersing the polyurethane foam in a degreasing liquid to degrease and wash, thereby obtaining a degreasing polyurethane foam; S2, roughening: immersing the degreased polyurethane foam in an alkaline roughening solution for roughening and washing to obtain a roughened polyurethane foam; S3, palladium activation: immersing the roughened polyurethane foam in the alkaline ion palladium activation solution for palladium activation, and washing to obtain an activated polyurethane foam; S4, reduction: immersing the activated polyurethane foam in a reducing solution for reduction, and washing to obtain a reduced polyurethane foam; S5, chemical copper plating: immersing the reduced polyurethane foam in a chemical copper plating solution for chemical copper plating, and washing to obtain chemically plated polyurethane foam; S6, electroplating copper: immersing the chemically plated polyurethane foam in an electroplating solution to electroplate copper, and drying to obtain an electroplated copper polyurethane foam; S7, heat treatment: placing the electroplated copper polyurethane foam into a heat treatment device, introducing a protective gas for thermal decomposition and reduction, and cooling to obtain the ultra-thin foam copper product.

3. The large-scale preparation method of ultrathin copper foam according to claim 2, characterized in that: In step S3, the alkaline ion palladium activation solution includes the following components: palladium chloride with a concentration of 0.01 to 0.2 g / L, ammonium chloride with a concentration of 0.1 to 0.5 g / L, an organic amine with a concentration of 0.05 to 0.3 g / L, and the balance water; the organic amine includes one or more of ethylenediamine, ethylene glycolamine, hydroxyethylethylenediamine, and phenylethylamine; In step S3, the pH value of the alkaline ion palladium activation solution is 9 to 11, and the pH value is adjusted with sodium hydroxide; In step S3, the palladium activation temperature is 40 to 60° C., and the palladium activation time is 40 to 60 seconds.

4. The large-scale preparation method of ultrathin copper foam according to claim 2, characterized in that: In step S5, the chemical copper plating solution includes the following components in concentrations: 10-15 g / L copper sulfate, 10-30 g / L potassium sodium tartrate, 5 g / L disodium EDTA, 16-24 ml / L formaldehyde, 8-12 g / L sodium hydroxide, and the balance water; In step S5, the temperature of the chemical copper plating is 35-40°C, and the time of the chemical copper plating is 5-10 minutes; in step S5, air stirring is performed during the chemical copper plating process.

5. The large-scale preparation method of ultrathin copper foam according to claim 2, characterized in that: In step S6, the electroplating solution includes the following components in concentrations: 80 g / L copper pyrophosphate, 300-350 g / L potassium pyrophosphate, 10-20 g / L HEDP, 2-5 ppm ammonia water, 2-4 ppm 2-mercaptobenzimidazole, and the balance water; In step S6, the temperature of the copper electroplating is 50-60°C; in step S6, the copper electroplating includes the following steps: pre-plating and electrodeposition.

6. The large-scale preparation method of ultrathin copper foam according to claim 5, characterized in that: Step S6 specifically includes the following steps: S6-A, completely immersing the chemically plated polyurethane foam into the electroplating solution for pre-plating to obtain an electroplated copper intermediate product a; the apparent current density of the pre-plating is 0.5 to 1 A / dm 2 ; The pre-plating time includes 2 to 5 minutes; S6-B, further subjecting the electroplated copper intermediate product a to the electroplating to obtain the electroplated copper intermediate product b; the apparent current density of the electroplating is 1 to 5 A / dm 2 ; The electrodeposition time includes 10 to 60 minutes; S6-C, drying the electroplated copper intermediate product b to obtain the electroplated copper polyurethane foam; The processes of step S6-A and step S6-B implement air stirring.

7. The large-scale preparation method of ultrathin copper foam according to claim 2, characterized in that: In step S1, the degreasing liquid includes the following components: a degreasing agent with a concentration of 10 to 100 ml / L, concentrated sulfuric acid with a concentration of 30 to 400 ml / L, and the balance of water; the degreasing agent includes the following ingredients: a complexing agent, an emulsifier, a penetrant, an adsorbent, an oil-in-water surfactant, and water; in step S1, the degreasing temperature includes 40 to 70° C., and the degreasing time includes 30 seconds to 5 minutes; In step S2, the roughening liquid includes the following components: a roughening agent with a concentration of 300 to 600 g / L and a balance of water; the roughening agent includes the following ingredients in weight percentage: 50% to 80% of alkaline compounds, 1% to 15% of oxidizing compounds, 1% to 10% of fluorides, 1% to 15% of complexing agents and 0.1% to 10% of surfactants; in step S2, the roughening temperature includes 50 to 80° C., and the roughening time includes 2 to 10 minutes.

8. The large-scale preparation method of ultra-thin copper foam according to claim 7, characterized in that: In the roughening agent, the alkaline compound includes one or more of sodium hydroxide, potassium hydroxide and lithium hydroxide; In the roughening agent, the oxidizing compound includes one or more of sodium persulfate, potassium persulfate, sodium perborate, potassium perborate, sodium hypochlorite and potassium hypochlorite; In the roughening agent, the fluoride includes one or more of sodium fluoride, potassium fluoride, sodium bifluoride, potassium bifluoride, ammonium bifluoride, fluoroborate and ammonium fluoride; In the roughening agent, the complexing agent includes one or more of EDTA, citrate, polyethylene polyamines and organic phosphonates; In the roughening agent, the surfactant includes one or more of dodecylbenzene sulfonate, dodecyl sulfonate, dodecyl sulfate, dodecylbenzene sulfate, alkyl polyoxyethylene ether, naphthalenesulfonic acid formaldehyde polymer, polyethylene glycol, fatty acid glyceride, fatty acid sorbitan ester and polysorbate.

9. The large-scale preparation method of ultra-thin copper foam according to claim 2, characterized in that: In step S4, the reducing solution includes one or more of a sodium hypophosphite aqueous solution or a hydrazine hydrate solution; in step S4, the reducing temperature includes 25 to 35° C., and the reducing time includes 40 to 60 seconds; In step S7, the thermal decomposition and reduction specifically include the following steps: heating the electroplated copper polyurethane foam to 500-700° C. and maintaining the temperature for 30-90 minutes, and naturally cooling the foam to room temperature to obtain the ultra-thin copper foam product; In step S7, the protective gas includes a mixture of H2 and N2, and the volume fraction of H2 in the protective gas includes 10%; in step S7, the heat treatment equipment includes a roller kiln; The cleaning method described in step S1 includes cleaning with deionized water; the cleaning method described in step S2 includes cleaning with deionized water; the cleaning method described in step S3 includes cleaning with deionized water; the cleaning method described in step S4 includes cleaning with deionized water; the cleaning method described in step S5 includes cleaning with deionized water.

10. The large-scale preparation method of ultra-thin copper foam according to any one of claims 1 to 9, characterized in that: The thickness of the polyurethane foam is 0.1-10 mm; the porosity of the polyurethane foam is ≥90%; and the pore size of the polyurethane foam is 20-500 μm.

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