Patterned ultrathin copper foil with carrier and preparation method thereof

Abstract

The invention provides a patterned ultrathin copper foil with a carrier and a preparation method thereof, and the preparation method comprises the following steps: pretreating a carrier copper foil, immersing the pretreated carrier copper foil in an electro-deposition liquid, and carrying out electro-deposition treatment to obtain a carrier copper foil containing a conductive layer; the electrodeposition liquid is a solution containing a conductive polymer prepolymer or a phosphoric acid solution dissolved with pyrrole; pasting a PI film on the surface of the conductive layer, and completing the patterning treatment of the insulating layer through ultraviolet laser direct writing or completing the patterning treatment of the insulating layer through mask exposure and alkaline development; electroplating copper in the exposed area of the conductive layer by using electrolyte; and carrying out surface treatment on the conductive layer subjected to copper electroplating to obtain the patterned ultrathin copper foil with the carrier. According to the invention, the patterned ultrathin copper layer can be directly formed on the surface of the stripping layer. The procedures of film pasting, exposure, development and etching of patterning of the ultrathin copper layer can be omitted, and the process is shortened by more than 50%; lateral erosion caused by multiple times of etching is reduced, and generation of copper-containing wastewater is reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of copper foil preparation, and particularly relates to a patterned ultra-thin copper foil with a carrier and a preparation method thereof. BACKGROUND

[0002] In modern electronic devices, the development of printed circuit board (PCB) and integrated circuit packaging technology puts forward higher requirements for materials and processes. As a core material, the carrier ultra-thin copper foil has excellent electrical conductivity and processing flexibility, and is widely recognized in high-end application scenarios. The structure of the carrier ultra-thin copper foil is composed of a carrier layer, a stripping layer and an ultra-thin copper layer. The carrier layer usually adopts an electrolytic copper foil or an aluminum foil with a thickness of 9-35 μm to provide necessary mechanical support. The stripping layer is responsible for realizing the controllable separation between the carrier and the ultra-thin copper layer. Commonly used materials include metal alloys (such as chromium, nickel and cobalt) or organic polymers (such as polyaniline). The thickness of the ultra-thin copper layer is generally between 1-5 μm, which is mainly used to form the pattern of the electronic circuit.

[0003] In the prior art, with the introduction of the modified semi-additive process (mSAP), after the carrier layer is stripped off after the hot pressing of the carrier ultra-thin copper foil and the substrate, the subsequent processes including film pasting, exposure, development, pattern plating, film stripping and flash etching are carried out, so as to realize the patterning of the ultra-thin copper layer. However, there are many problems in this series of procedures, which seriously affect the production efficiency and product quality.

[0004] Firstly, the existing ultra-thin copper layer patterning process usually needs multiple photoetching or etching treatments, which leads to complicated procedures and long process flow. This not only increases the production cycle, but also reduces the yield to a certain extent, resulting in the generation of a large number of defective products. Secondly, the patterned method through multiple etching is easy to cause the loss of the ultra-thin copper layer, thereby affecting the final material utilization rate. In addition, since the line width of the ultra-thin copper layer is easy to distort, the performance of the final product may not meet the design requirements. Finally, the treatment of wastewater containing copper etching solution is not only complex, but also the treatment cost accounts for more than 30% of the production cost, further increasing the operating burden of enterprises. SUMMARY

[0005] In view of the defects of the prior art, the application provides a patterned ultra-thin copper foil with a carrier and a preparation method thereof. By optimizing the structural design of the stripping layer, the direct patterning of the ultra-thin copper layer is realized, and the complex procedures in the traditional patterning process are significantly simplified.

[0006] In the first aspect, the application provides a patterned ultra-thin copper foil with a carrier and a preparation method thereof, which comprises: Step 1: pretreatment of the carrier copper foil, wherein the carrier copper foil adopts an electrolytic copper foil with a thickness of 9-35 μm; Step 2: Immerse the pretreated carrier copper foil in the electrodeposition solution and perform electrodeposition to obtain a carrier copper foil containing a conductive layer; the electrodeposition solution is a solution containing a conductive polymer prepolymer or a phosphoric acid solution containing pyrrole. Step 3: Apply a PI film to the surface of the conductive layer, and complete the patterning of the insulating layer by direct writing with ultraviolet laser or by exposure through a mask and alkaline development. Step 4: Electroplating copper in the exposed areas of the conductive layer using an electrolyte solution; Step 5: Perform surface treatment on the conductive layer after copper electroplating to obtain patterned ultrathin copper foil with carrier.

[0007] This invention achieves patterned ultrathin copper layers directly on the surface of the release layer through patterned design. By combining the patterning of the conductive and insulating layers, the cumbersome photolithography and etching steps in the traditional patterning process are reduced. After reducing multiple etching processes, the patterning process of the ultrathin copper layer significantly reduces material loss and distortion risks, thereby significantly improving product yield and reducing the probability of defective products.

[0008] Preferably, step 1 includes: The carrier copper foil is placed in an acid pickling solution to remove the oxide layer; The pickling solution used is a sulfuric acid aqueous solution with a concentration of 140-150 g / L; the pickling temperature is 34-40℃; and the pickling time is 10-20 s.

[0009] Preferably, step 2 includes: The concentration of pyrrole in the phosphoric acid solution is 0.2-0.5 mol / L; the concentration of phosphoric acid is 0.4-1.0 mol / L.

[0010] The current density for electrodeposition is 0.03-0.09 mA / cm²; the electrodeposition time is 0.5 min-12 min.

[0011] Preferably, step 3 includes: Ultraviolet laser direct writing uses a laser with a wavelength of 355nm and an accuracy of ±2μm; The dimensions of the pattern features formed after the insulating layer patterning process are line width / line spacing = 5μm / 5μm.

[0012] Preferably, step 4 includes: The electrolyte contains 70-80 g / L copper ions, 90-110 g / L sulfuric acid, 10.0-20.0 mg / L sodium didithiopropane sulfonate, 5.0-10.0 mg / L hydroxyethyl cellulose, 15.0-30.0 mg / L polyethylene glycol, and 10.0-20.0 mg / L hydrolyzed collagen. The electrolysis conditions are: current density 54-64 A / m2, electrolyte flow rate 30-35 m3 / h, and electrolyte temperature 40-42℃.

[0013] Preferably, step 5 includes: Step 5.1: Pickling; wherein the pickling solution contains a sulfuric acid aqueous solution with a concentration of 140-150 g / L, and the pickling temperature is 34-40℃; Step 5.2: Roughening; The concentration of copper ions in the roughening solution is 12-14 g / L, the concentration of sulfuric acid is 120-130 g / L, the concentration of sodium tungstate is 60-80 mg / L, and the temperature of the roughening solution is 30-35℃; Step 5.3: Curing; The copper concentration in the curing tank is 50-56 g / L, the sulfuric acid concentration is 90-120 g / L, and the temperature is 40-46℃; Step 5.4: One water wash; use ultrapure water, temperature 25-35℃, pH 6.8-7.2; Step 5.5: Anti-oxidation treatment; The concentration of nickel ions in the anti-oxidation treatment tank is 1.5-2.5 g / L, the concentration of zinc ions is 3.5-4.5 g / L, the concentration of K4P2O7 is 70-100 g / L, the pH value is 10-11, and the temperature is 25-35℃. Step 5.6: Secondary water wash; use ultrapure water, temperature 25-35℃, pH 6.8-7.2; Step 5.7: Silanization; Spraying an organosilane coupling agent; The concentration of the organosilane coupling agent is 1.0-1.5 g / L, the pH is 9-12, and the temperature is 25-35℃; Step 5.8: Drying; the drying temperature is 130-140℃, and the time is 5-10 seconds; Step 5.9: Rewinding; After rewinding, a patterned ultrathin copper foil with a carrier is obtained.

[0014] In a second aspect, the present invention also provides a patterned ultrathin copper foil with a carrier. Preferably, the ultrathin copper foil is prepared by the patterned ultrathin copper foil with a carrier as described in the first aspect. The ultrathin copper foil includes: a carrier layer, a release layer and an ultrathin copper layer. The carrier copper foil is an electrolytic copper foil with a thickness of 9-35 μm; the surface roughness Rz of the carrier layer is ≤1.5 μm; The release layer consists of a conductive layer and an insulating layer from bottom to top; The conductive layer is made of polyaniline and / or polypyrrole conductive polymer, with a thickness of 0.01-1 μm; the insulating layer and the ultrathin copper layer are both 1-5 μm thick.

[0015] Preferably, the insulating layer is prepared from polyimide (PI) by mechanical or laser processing, or from a photosensitive polybenzoxazole (PBO) thin film photomask. The pattern of the insulating layer is the opposite of the desired copper circuit pattern.

[0016] Preferably, the surface roughness Rz of the ultrathin copper laminate is ≤1.5μm.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention proposes a patterned ultrathin copper foil with a carrier and its preparation method. By patterning the release layer, which consists of a conductive layer and an insulating layer, the ultrathin copper layer is directly patterned on the surface of the release layer. This eliminates the need for multiple independent photolithography and etching processes, significantly shortening the production chain and reducing the difficulty and complexity of the process. By integrating the preparation of the conductive layer, the patterning of the insulating layer (UV laser direct writing or mask exposure + alkaline development), and the selective electroplating of the ultrathin copper layer (electroplation of the exposed areas of the conductive layer), the transfer and connection costs between processes are reduced, improving production efficiency.

[0018] The solution described in this invention avoids multiple chemical etching processes, fundamentally eliminating the risks of side etching, over-etching, copper loss, and pattern distortion caused by the etching process. The ultra-thin copper foil product with a carrier obtained through this solution, after being laminated with a substrate, only requires peeling off the carrier and release layer to directly obtain a board with patterned circuitry, providing great convenience for downstream PCB manufacturers. Attached Figure Description

[0019] Fig. 1 This is a schematic diagram illustrating the principle of patterned ultrathin copper foil with a carrier and its preparation method in an embodiment of the present invention.

[0020] Fig. 2 This is a flowchart illustrating the patterned ultrathin copper foil with a carrier and its preparation method according to an embodiment of the present invention.

[0021] Fig. 3 This is a diagram illustrating the patterning process of ultra-thin copper foil according to an embodiment of the present invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0023] Example 1: As Figs. 1-3As shown, this invention proposes a patterned ultrathin copper foil with a carrier and its preparation method, comprising: Step 1: Pre-treat the carrier copper foil, wherein the carrier copper foil is an electrolytic copper foil with a thickness of 9-35μm; place the carrier copper foil in an acid pickling solution to remove the oxide layer; wherein the acid pickling solution is a sulfuric acid aqueous solution with a concentration of 140-150g / L; the acid pickling temperature is 34-40℃; and the acid pickling time is 10-20s.

[0024] In this embodiment, an electrolytic copper foil with a thickness of 9 μm can be selected as the carrier copper foil, and the following pretreatment is performed: Preparation of pickling solution: Prepare a sulfuric acid aqueous solution with a concentration of 140 g / L and stir until homogeneous; Control the pickling environment: Adjust the temperature of the pickling solution to 34℃; Pickling treatment: Immerse the carrier copper foil completely in the above pickling solution and keep it for 10 seconds; Post-processing: Remove the copper foil, rinse the surface with deionized water to remove residual acid, and then dry it to complete the pre-treatment of the carrier copper foil.

[0025] In this embodiment, an electrolytic copper foil with a thickness of 35 μm can also be selected as the carrier copper foil, and the following pretreatment is performed: Preparation of pickling solution: Prepare a sulfuric acid aqueous solution with a concentration of 150 g / L and stir until homogeneous; Control the pickling environment: Adjust the temperature of the pickling solution to 40℃; Pickling treatment: Immerse the carrier copper foil completely in the above pickling solution and keep it for 20 seconds; Post-processing: Remove the copper foil, rinse the surface with deionized water to remove residual acid, and then dry it to complete the pre-treatment of the carrier copper foil.

[0026] In this embodiment, an electrolytic copper foil with a thickness of 20 μm can also be selected as the carrier copper foil, and the following pretreatment is performed: Preparation of pickling solution: Prepare a sulfuric acid aqueous solution with a concentration of 145 g / L and stir until homogeneous; Control the pickling environment: Adjust the temperature of the pickling solution to 37℃; Pickling treatment: Immerse the carrier copper foil completely in the above pickling solution and keep it for 15 seconds; Post-processing: Remove the copper foil, rinse the surface with deionized water to remove residual acid, and then dry it to complete the pre-treatment of the carrier copper foil.

[0027] After this pretreatment, the surface of the carrier copper foil is clean and activated, the original oxide layer is completely removed, and a fresh copper surface is exposed. The roughness Rz of the contact surface with the electrolyte is controlled below 1.5μm, which lays a good foundation for the subsequent electrodeposition to prepare a uniform conductive layer.

[0028] Step 2: Immerse the pretreated carrier copper foil in the electrodeposition solution and perform electrodeposition to obtain a carrier copper foil containing a conductive layer; the electrodeposition solution is a solution containing a conductive polymer prepolymer or a phosphoric acid solution containing pyrrole. Preferably, the concentration of pyrrole in the phosphoric acid solution is 0.2-0.5 mol / L; and the concentration of phosphoric acid is 0.4-1.0 mol / L.

[0029] The current density for electrodeposition is 0.03-0.09 mA / cm²; the electrodeposition time is 0.5 min-12 min.

[0030] In this embodiment, the preferred application case 1, which uses a conductive layer electrodeposition treatment with a phosphoric acid solution containing dissolved pyrrole, follows these steps: Electrodeposition solution preparation: Prepare a pyrrole-containing phosphoric acid solution with a pyrrole concentration of 0.2 mol / L and a phosphoric acid concentration of 0.4 mol / L, and stir until completely dissolved; Pretreated carrier copper foil: 9μm electrolytic copper foil pretreated in step 1 was used; Electrodeposition parameters: current density 0.03 mA / cm², electrodeposition time 12 min; Electrodeposition operation: The pretreated carrier copper foil is completely immersed in the above electrodeposition solution, and electrodeposition is performed under the set parameters; Post-processing: Remove the copper foil, rinse the surface with deionized water to remove residual electrolyte, and dry to obtain a carrier copper foil with a conductive layer (polypyrrole layer) formed on the surface.

[0031] In this embodiment, the preferred application case 2, which uses a conductive layer electrodeposition treatment with a phosphoric acid solution containing dissolved pyrrole, follows these steps: Electrodeposition solution preparation: Prepare a pyrrole-containing phosphoric acid solution with a pyrrole concentration of 0.35 mol / L and a phosphoric acid concentration of 0.7 mol / L, and stir until completely dissolved; Pretreated carrier copper foil: 20μm electrolytic copper foil pretreated in step 1 was used; Electrodeposition parameter settings: current density is 0.06 mA / cm², electrodeposition time is 6 min; Electrodeposition operation: The pretreated carrier copper foil is completely immersed in the above electrodeposition solution, and electrodeposition is performed under the set parameters; Post-processing: Remove the copper foil, rinse the surface with deionized water to remove residual electrolyte, and dry to obtain a carrier copper foil with a conductive layer (polypyrrole layer) formed on the surface.

[0032] In this embodiment, the preferred application case 3 of conductive layer electrodeposition treatment using a solution containing a conductive polymer prepolymer is as follows: Electrodeposition solution preparation: Polyaniline prepolymer solution (10% solid content) was selected as the electrodeposition solution; Pretreated carrier copper foil: 15μm electrolytic copper foil pretreated in step 1 was used; Electrodeposition parameter settings: current density is 0.05 mA / cm², electrodeposition time is 8 min; Electrodeposition operation: The pretreated carrier copper foil is completely immersed in the above electrodeposition solution, and electrodeposition is performed under the set parameters; Post-processing: Remove the copper foil, rinse the surface with deionized water to remove residual electrolyte, and dry at 80°C to obtain a carrier copper foil with a polyaniline conductive layer formed on the surface.

[0033] The conductive layer prepared using the above parameters is bluish-black in color, with a uniform and defect-free surface. This conductive layer has a thickness of approximately tens to hundreds of nanometers, low sheet resistance, and excellent conductivity and adhesion, providing an excellent substrate for subsequent lamination and patterning processes.

[0034] Step 3: Apply a PI film to the surface of the conductive layer, and complete the patterning of the insulating layer by direct writing with ultraviolet laser or by exposure through a mask and alkaline development. Ultraviolet laser direct writing uses a laser with a wavelength of 355nm and an accuracy of ±2μm; The dimensions of the pattern features formed after the insulating layer patterning process are line width / line spacing = 5μm / 5μm.

[0035] In a specific embodiment, an ultraviolet laser direct writing process is employed, which specifically includes: Applying PI film: On the surface of the conductive layer carrier copper foil after step 2, apply a 3μm thick polyimide (PI) film smoothly, ensuring no bubbles or wrinkles. Laser direct writing parameter settings: Use a 355nm wavelength ultraviolet laser device, set the pattern accuracy control to ±2μm, and preset the pattern feature size to line width 5μm / line spacing 5μm; Patterning process: The copper foil carrier on which the PI film is applied is fixed on the laser processing platform, and ultraviolet laser direct writing is performed according to the preset circuit pattern. The PI film in the area where the conductive layer needs to be exposed is removed by laser ablation. Post-processing: Remove the residue generated by laser processing, blow the surface with compressed air to obtain a carrier copper foil with a patterned insulating layer (PI film), wherein the area where the insulating layer is retained is opposite to the desired copper circuit pattern, and the exposed conductive layer area has a line width / spacing of 5μm / 5μm.

[0036] In a specific embodiment, a mask exposure + alkaline development process is used, specifically including: Photosensitive PI film application: A photosensitive polyimide film (3μm thick) is applied flatly to the surface of a carrier copper foil containing a conductive layer, and vacuum pressing is used to ensure a tight bond. Mask alignment: The mask with the preset pattern (the pattern features a line width of 5μm / line spacing of 5μm, which is the opposite of the desired copper circuit pattern) is precisely covered on the surface of the photosensitive PI film, and the alignment accuracy is controlled within ±1μm; Exposure process: The area covered by the mask was exposed using an ultraviolet exposure machine (wavelength 365nm), and the exposure energy was controlled at 200mJ / cm². Alkaline development: Immerse the exposed carrier copper foil in a 2% sodium carbonate aqueous solution (developer) and develop at 30°C for 60 seconds to remove the unexposed photosensitive PI film area and expose the underlying conductive layer. Curing process: After development, the carrier copper foil is placed in a 150℃ oven and baked for 30 minutes to completely cure the residual PI film, finally obtaining an insulating layer with a line width of 5μm and a line spacing of 5μm, wherein the exposed conductive layer area is consistent with the desired copper circuit pattern.

[0037] Step 3 yielded a patterned insulating layer. This layer, composed of 3 μm thick polyimide (PI), was patterned inversely to the design, creating a clear structure with a linewidth / spacing of 5 μm. The areas where PI was removed precisely exposed the underlying conductive layer; these exposed areas serve as "seed layers" and growth areas for subsequent copper plating. The areas covered by PI, on the other hand, provided excellent insulation. This process eliminates the need for photolithography masks, resulting in a streamlined workflow ideal for high-precision, fast-response prototyping and small-batch production.

[0038] Step 4: Electroplating copper in the exposed areas of the conductive layer using an electrolyte solution; Preferably, step 4 includes: The electrolyte contains 70-80 g / L copper ions, 90-110 g / L sulfuric acid, 10.0-20.0 mg / L sodium didithiopropane sulfonate, 5.0-10.0 mg / L hydroxyethyl cellulose, 15.0-30.0 mg / L polyethylene glycol, and 10.0-20.0 mg / L hydrolyzed collagen. The electrolysis conditions are: current density 54-64 A / m2, electrolyte flow rate 30-35 m3 / h, and electrolyte temperature 40-42℃.

[0039] In a specific embodiment, the following are examples of copper plating options for the exposed areas of the conductive layer: Prioritize electrolyte preparation: Prepare a copper plating electrolyte with the following component concentrations: Copper ions: 70 g / L (added in the form of copper sulfate) Sulfuric acid: 90g / L Sodium polydisulfide dipropane sulfonate: 10.0 mg / L Hydroxyethyl cellulose: 5.0 mg / L Polyethylene glycol: 15.0 mg / L Hydrolyzed collagen: 10.0 mg / L Stir until all components are completely dissolved, and adjust the pH of the solution to 1.0-1.5.

[0040] Electroplating parameter settings: Current density: 54A / m² Electrolyte flow rate: 30 m³ / h Electrolyte temperature: 40℃ Electroplating operation: The copper foil with patterned insulating layer treated in step 3 is used as the cathode and the pure copper plate is used as the anode. The copper foil is placed in the electrolyte and electroplated under the set parameters until the thickness of the ultrathin copper layer reaches 1μm.

[0041] Post-processing: Remove the copper foil, rinse the surface with deionized water to remove residual electrolyte, and dry to obtain a carrier copper foil with an ultrathin copper layer formed in the exposed area of ​​the conductive layer. Preferably, the electrolyte configuration can also be other options, for example, the concentrations of each component are as follows: Copper ions: 75 g / L (added in the form of copper sulfate) Sulfuric acid: 100g / L Sodium polydisulfide dipropane sulfonate: 15.0 mg / L Hydroxyethyl cellulose: 7.5 mg / L Polyethylene glycol: 22.5 mg / L Hydrolyzed collagen: 15.0 mg / L Stir until all components are completely dissolved, and adjust the pH of the solution to 1.0-1.5.

[0042] Electroplating parameter settings: Current density: 59A / m² Electrolyte flow rate: 32.5 m³ / h Electrolyte temperature: 41℃ The above embodiments, by precisely controlling the electrolyte composition and electroplating process parameters, can form an ultra-thin copper layer with uniform thickness (1-5μm) and high density in the exposed area of ​​the conductive layer. The copper layer is firmly bonded to the conductive layer, and the surface roughness Rz of the lamination surface is ≤1.5μm, which meets the surface quality requirements of the subsequent lamination process.

[0043] Step 5: Perform surface treatment on the conductive layer after copper electroplating to obtain patterned ultrathin copper foil with carrier.

[0044] Preferably, step 5 includes: Step 5.1: Pickling; wherein the pickling solution contains a sulfuric acid aqueous solution with a concentration of 140-150 g / L, and the pickling temperature is 34-40℃; pickling removes the slight oxide layer and contaminants on the surface of the electroplated copper layer, exposing a fresh and activated copper surface, ensuring the adhesion of subsequent treatment layers.

[0045] Step 5.2: Roughening; The concentration of copper ions in the roughening solution is 12-14 g / L, the concentration of sulfuric acid is 120-130 g / L, the concentration of sodium tungstate is 60-80 mg / L, and the temperature of the roughening solution is 30-35℃; After roughening, a tiny uneven structure is formed on the surface of the copper layer, which significantly increases the specific surface area, thereby enhancing the mechanical interlocking and bonding force with subsequent layers (such as anti-oxidation layer, resin).

[0046] Step 5.3: Curing; The copper concentration in the curing tank is 50-56 g / L, the sulfuric acid concentration is 90-120 g / L, and the temperature is 40-46℃; Curing densifies and smooths the roughened, loose, and sharp copper crystal structure, improves the physical strength and heat resistance of the copper layer, and prevents copper powder from falling off.

[0047] Step 5.4: First water wash; use ultrapure water, temperature 25-35℃, pH 6.8-7.2; thoroughly wash away the residual acidic electrolyte on the substrate surface to prevent contamination of subsequent bath solutions.

[0048] Step 5.5: Anti-oxidation treatment; The concentration of nickel ions in the anti-oxidation treatment tank is 1.5-2.5 g / L, the concentration of zinc ions is 3.5-4.5 g / L, the concentration of K4P2O7 is 70-100 g / L, the pH value is 10-11, and the temperature is 25-35℃; A dense zinc-nickel alloy layer is formed on the surface of the copper layer. This layer can effectively prevent the copper surface from being oxidized and discolored during storage and transportation, and at the same time provide good heat resistance in the subsequent pressing process.

[0049] Step 5.6: Second water wash; use ultrapure water, temperature 25-35℃, pH 6.8-7.2; wash away the residual alkaline anti-oxidation solution on the surface, providing a clean surface for subsequent silanization treatment.

[0050] Step 5.7: Silanization; Spraying organosilicon coupling agent; The concentration of the organosilicon coupling agent is 1.0-1.5 g / L, the pH is 9-12, and the temperature is 25-35℃; The silane coupling agent forms an extremely thin molecular film on the surface of the copper layer, with one end of its functional group bonded to the metal surface, and the other end of its organic functional group forming chemical bonds with the resin material in the PCB substrate, greatly improving the bonding strength between the copper foil and the prepreg (PP).

[0051] Step 5.8: Drying; the drying temperature is 130-140℃, and the time is 5-10 seconds; to thoroughly remove surface moisture and promote the condensation reaction of the silane coupling agent, forming a stable chemical film layer on the copper surface. Step 5.9: Rewinding; After rewinding, a patterned ultrathin copper foil with a carrier is obtained.

[0052] The patterned ultrathin copper foil prepared in this embodiment has a surface roughness Ra ≤ 0.5 μm, no oxidation discoloration after oxidation resistance test (155℃, 2h), and a peel strength ≥ 1.0 N / mm to FR-4 substrate. All properties meet the manufacturing requirements of high-end fine circuit PCBs.

[0053] Specifically, surface treatment of the conductive layer includes, for example: 1. Prepare an aqueous solution of sulfuric acid with a concentration of 140 g / L as the pickling solution, and control the temperature at 34℃; immerse the copper foil carrier that has been electroplated into the pickling solution, and remove it after 15 seconds.

[0054] 2. Preparation of roughening solution: 12 g / L copper ions (added in the form of copper sulfate), 120 g / L sulfuric acid, and 60 mg / L sodium tungstate are stirred evenly and the temperature is adjusted to 30℃. The pickled copper foil is immersed in the roughening solution for 30 seconds to form a micro-rough surface.

[0055] 3. Prepare the curing solution: copper concentration 50g / L, sulfuric acid 90g / L, temperature controlled at 40℃; immerse the roughened copper foil in the curing solution for 20s to enhance the adhesion of the copper layer.

[0056] 4. Rinse the copper foil surface with ultrapure water (temperature 25℃, pH 6.8) to remove residual chemicals. Rinse for 10 seconds.

[0057] 5. Preparation of anti-oxidation treatment solution: nickel ions 1.5g / L, zinc ions 3.5g / L, K4P2O7 70g / L, adjust pH to 10, and control temperature at 25℃; immerse copper foil in the treatment solution for 3s to form an anti-oxidation protective film.

[0058] 6. Rinse the copper foil surface again with ultrapure water (temperature 25℃, pH 6.8) for 10 seconds to ensure that any residual chemicals are removed.

[0059] 7. Prepare an organosilane coupling agent solution (concentration 1.0 g / L), adjust the pH to 9, and control the temperature at 25℃; uniformly cover the copper foil surface by spraying for 5 seconds to enhance the subsequent adhesion to the substrate.

[0060] 8. Place the silanized copper foil in a 130℃ oven and dry for 5 seconds to remove surface moisture.

[0061] 9. After the above processing, the copper foil is wound up at a speed of 50 m / min to obtain a patterned ultrathin copper foil product with a carrier.

[0062] Optionally, surface treatment of the conductive layer may include, for example: 1. Prepare an aqueous solution of sulfuric acid with a concentration of 150 g / L as the pickling solution, and control the temperature at 40℃; immerse the copper foil carrier that has been electroplated into the pickling solution, and remove it after 15 seconds.

[0063] 2. Preparation of roughening solution: 14 g / L copper ions, 130 g / L sulfuric acid, 80 mg / L sodium tungstate, and temperature adjusted to 35℃; immerse the acid-washed copper foil in the roughening solution for 30 seconds.

[0064] 3. Prepare the curing solution: copper concentration 56g / L, sulfuric acid 120g / L, temperature controlled at 46℃; immerse the roughened copper foil in the curing solution for 20s.

[0065] 4. Rinse the copper foil surface with ultrapure water (temperature 35℃, pH 7.2) for 10 seconds.

[0066] 5. Prepare the anti-oxidation treatment solution: nickel ions 2.5g / L, zinc ions 4.5g / L, K4P2O7 100g / L, adjust the pH to 11, and control the temperature at 35℃; immerse the copper foil in the treatment solution for 3s.

[0067] 6. Rinse the copper foil surface again with ultrapure water (temperature 35℃, pH 7.2) for 10 seconds.

[0068] 7. Prepare an organosilane coupling agent solution (concentration 1.5g / L), adjust the pH to 12, and control the temperature at 35℃; treat the copper foil surface by spraying for 5 seconds.

[0069] 8. Place the copper foil in a 140℃ oven and dry for 10 seconds.

[0070] 9. Rewind at a speed of 50 m / min to obtain a patterned ultrathin copper foil product with a carrier.

[0071] The above embodiments, through multi-step surface treatment, can effectively remove impurities on the surface of the ultrathin copper layer, enhance the density of the copper layer, form an anti-oxidation protective film, and improve the bonding performance with the substrate. The resulting carrier-patterned ultrathin copper foil meets the requirements for the preparation of high-precision circuit boards. Its ultrathin copper layer has uniform thickness (1-5μm), surface roughness Rz≤1.5μm, and excellent anti-oxidation performance.

[0072] In summary, this invention achieves patterned ultrathin copper layers directly on the surface of the release layer through patterned design. By combining the patterning of the conductive and insulating layers, the cumbersome photolithography and etching steps in traditional patterning processes are reduced. By eliminating multiple etching processes, the patterning process of the ultrathin copper layer significantly reduces material loss and distortion risks, thereby significantly improving product yield and reducing the probability of defective products.

[0073] In a second aspect, the present invention also provides a patterned ultrathin copper foil with a carrier. Preferably, the ultrathin copper foil is prepared by the patterned ultrathin copper foil with a carrier as described in the first aspect. The ultrathin copper foil includes: a carrier layer, a release layer and an ultrathin copper layer. The carrier copper foil is an electrolytic copper foil with a thickness of 9-35 μm; the surface roughness Rz of the carrier layer is ≤1.5 μm; The release layer consists of a conductive layer and an insulating layer from bottom to top; The conductive layer is made of polyaniline and / or polypyrrole conductive polymer, with a thickness of 0.01-1 μm; the insulating layer and the ultrathin copper layer are both 1-5 μm thick.

[0074] Preferably, the insulating layer is prepared from polyimide (PI) by mechanical or laser processing, or from a photosensitive polybenzoxazole (PBO) thin film photomask. The pattern of the insulating layer is the opposite of the desired copper circuit pattern.

[0075] Preferably, the surface roughness Rz of the ultrathin copper laminate is ≤1.5μm.

[0076] In a preferred embodiment: polypyrrole is used as the conductive layer + ultraviolet laser direct writing of the PI insulating layer; The structure of the patterned ultrathin copper foil product with carrier is as follows: Carrier layer: 9μm thick electrolytic copper foil is selected. After pretreatment, the surface roughness Rz=1.2μm, with no oxide layer and no impurities, providing a flat substrate for subsequent layer structures. Release layer: includes a conductive layer and an insulating layer; Conductive layer: Made of polypyrrole conductive polymer, formed by electrodeposition process, with a thickness of 0.05μm, uniformly covered by carrier layer on the surface, and stable conductivity (sheet resistance ≤50Ω / □). Insulating layer: A polyimide (PI) film with a thickness of 3μm is selected and patterned by ultraviolet laser direct writing process with a laser wavelength of 355nm and a pattern accuracy of ±2μm. The resulting insulating layer pattern has a line width / line spacing of 5μm / 5μm and is the opposite of the desired copper circuit pattern (i.e., the area of ​​the insulating layer is the non-circuit area, and the area of ​​the exposed conductive layer is the circuit area). Ultra-thin copper layer: prepared by selective electroplating in the exposed area of ​​the conductive layer, with a thickness of 3μm, a surface roughness Rz=1.3μm, high copper layer density (relative density ≥98%), no pinholes or cracks, and the circuit pattern is perfectly matched with the exposed area of ​​the insulating layer, with line width / line spacing = 5μm / 5μm.

[0077] The corresponding preparation process is as follows: Follow step 1 to perform acid pickling pretreatment on 9μm electrolytic copper foil (sulfuric acid concentration 140g / L, temperature 34℃, time 10s), remove the surface oxide layer and then dry. Prepare a pyrrole-containing phosphoric acid solution (pyrrole concentration 0.2 mol / L, phosphoric acid concentration 0.4 mol / L) according to step 2, and electrodeposit at a current density of 0.03 mA / cm² for 12 min to form a polypyrrole conductive layer on the surface of the carrier layer. Following step 3, a 3μm PI film is deposited on the surface of the conductive layer. A pattern with a line width and spacing of 5μm / 5μm is etched by direct writing with a 355nm ultraviolet laser (accuracy ±2μm). After removing the PI film in the exposed area, the residue is cleaned up. Prepare the copper plating electrolyte (70g / L copper ions, 90g / L sulfuric acid, and 10.0mg / L sodium dithiosulfate sulfonate and other additives) according to step 4, and perform electroplating at a current density of 54A / m² and an electrolyte temperature of 40℃ until the ultrathin copper layer reaches a thickness of 3μm. Perform surface treatment as per step 5 (pickling → roughening → curing → water washing → anti-oxidation → silanization → drying), and finally rewind to obtain patterned ultrathin copper foil with carrier.

[0078] Based on the above preparation process, a patterned ultrathin copper foil product with a carrier is obtained. The layers are firmly bonded, and after a 180° bending test (bending radius 1mm, 10 cycles), there is no delamination or circuit breakage. Furthermore, the surface roughness Rz of the laminate is ≤1.5μm, and after lamination with FR-4 substrate (lamination temperature 180℃, pressure 3MPa), the peel strength is ≥1.5N / mm, meeting the requirements for the preparation of fine-line PCB boards.

[0079] In another preferred embodiment: polyaniline is used as the conductive layer + a mask is used to expose the PBO insulating layer; The product structure and parameters are as follows: Carrier layer: 20μm thick electrolytic copper foil is selected. After pretreatment, the surface roughness Rz=1.4μm. The copper foil has excellent mechanical properties (tensile strength ≥300MPa, elongation ≥8%) and can withstand the tension in subsequent processing. Peel-off layer: Conductive layer: Made of polyaniline conductive polymer, electrodeposited thickness 0.5μm, good surface smoothness (roughness Rz=0.8μm), excellent conductivity (sheet resistance ≤30Ω / □), and bonding force with carrier layer and insulating layer ≥0.8N / mm. Insulating layer: A photosensitive polybenzoxazole (PBO) film with a thickness of 5μm is selected. It is patterned by mask exposure + alkaline development process. The exposure wavelength is 365nm and the developer is a 2% sodium carbonate aqueous solution (30℃, 60s). The resulting insulating layer pattern has a line width / line spacing of 5μm / 5μm and a pattern edge neatness of ≤1μm, which is the opposite of the desired copper circuit pattern. Ultra-thin copper layer: electroplating thickness 5μm, bonding surface roughness Rz=1.4μm, high line accuracy (line width deviation ≤±0.5μm), copper layer purity ≥99.9%, meeting the requirements of high frequency signal transmission (high frequency loss ≤0.1dB / cm, at 1GHz frequency).

[0080] The process for preparing a product with polyaniline as the conductive layer and PBO insulating layer exposed by a mask based on the method described in Example 1 is as follows: Step 1: Pickle the 20μm electrolytic copper foil (sulfuric acid concentration 145g / L, temperature 37℃, time 15s) to remove the oxide layer, then wash and dry. Step 2: Select polyaniline prepolymer solution (10% solid content) as electrodeposition solution, electrodeposit at a current density of 0.05 mA / cm² for 8 min, and dry at 80℃ to form a 0.5 μm thick polyaniline conductive layer. Step 3: Apply a 5μm photosensitive PBO film, cover it with a mask with a preset 5μm / 5μm pattern (alignment accuracy ±1μm), expose to ultraviolet light (energy 200mJ / cm²), then develop with alkaline solution and cure (150℃, 30min) to form a patterned insulating layer. Step 4: Prepare the electroplating solution (75g / L copper ions, 100g / L sulfuric acid, and additives added in proportion), and electroplat at a current density of 59A / m² and an electrolyte flow rate of 32.5m³ / h to control the thickness of the ultrathin copper layer to 5μm. Step 5: Perform pickling (sulfuric acid 145g / L, 37℃), roughening (copper ions 13g / L, sulfuric acid 125g / L), anti-oxidation (nickel ions 2.0g / L), silanization (concentration 1.25g / L), and drying (135℃, 8s) in sequence, and then rewind to obtain the finished product.

[0081] Based on the above preparation process, a patterned ultrathin copper foil product with a carrier is obtained. The insulating layer uses PBO material, which has excellent high-temperature resistance (glass transition temperature ≥300℃). After being placed at a welding temperature of 260℃ for 10 seconds, the circuit shows no deformation or failure. After temperature cycling test (-40℃~125℃, 100 cycles), the dimensional change rate of the ultrathin copper layer circuit is ≤0.1%, meeting the dimensional accuracy requirements of precision electronic equipment. The preparation process reduces etching steps, generates no large amount of copper-containing waste liquid, and the product has a recyclability rate of ≥90%, complying with RoHS environmental standards.

[0082] In another preferred embodiment: a polyaniline-polypyrrole composite conductive layer is used, followed by laser etching of the PI insulating layer; The structure and parameters of patterned ultrathin copper foil products with carriers include: Carrier layer: 35μm thick electrolytic copper foil is selected. After pretreatment, the surface roughness Rz=1.5μm. The copper foil has good thickness uniformity (thickness deviation ≤±0.5μm), which is suitable for large-scale continuous production. Peel-off layer: Conductive layer: A polyaniline-polypyrrole composite system is adopted. Polyaniline (thickness 0.3μm) is first electrodeposited, followed by polypyrrole (thickness 0.2μm), with a total thickness of 0.5μm. The composite conductive layer combines the stability of polyaniline with the high conductivity of polypyrrole (sheet resistance ≤25Ω / □), and the bonding force with the carrier layer is ≥1.0N / mm. Insulation layer: Made of polyimide (PI) film with a thickness of 1μm, patterned by ultraviolet laser etching process with laser precision of ±2μm, pattern line width / line spacing = 5μm / 5μm, insulation layer breakdown voltage ≥500V, insulation resistance ≥10¹²Ω, effectively isolating current in non-circuit areas. Ultra-thin copper layer: electroplating thickness 1μm, surface roughness Rz=1.1μm, no burrs on the circuit edge (burr length ≤0.5μm), fine and uniform copper layer crystals, which can adapt to the bending requirements of flexible substrates (bending times ≥1000 times, bending radius 0.5mm).

[0083] The preparation was carried out based on the preparation method described in Example 1, specifically including: Step 1: Pickle the 35μm electrolytic copper foil (sulfuric acid concentration 150g / L, temperature 40℃, time 20s) to remove the oxide layer, then rinse with ultrapure water and dry. Step 2: First, a 0.3 μm polyaniline layer is formed by electrodeposition (current density 0.05 mA / cm², time 5 min) using a polyaniline prepolymer solution (solid content 10%); then, a 0.2 μm polypyrrole layer is formed by electrodeposition at 0.09 mA / cm² for 0.5 min using a pyrrole-phosphoric acid solution (pyrrole 0.5 mol / L, phosphoric acid 1.0 mol / L), thus forming a composite conductive layer. Step 3: Apply a 1μm PI film, etch a 5μm / 5μm pattern using a 355nm ultraviolet laser, clean up any residue, and check the integrity of the insulation layer. Step 4: Prepare the electroplating solution (80g / L copper ions, 110g / L sulfuric acid), and electroplat at a current density of 64A / m² and an electrolyte flow rate of 35m³ / h, controlling the thickness of the ultrathin copper layer to 1μm. Step 5: Process according to the surface treatment process (pickling → roughening → curing → anti-oxidation → silanization → drying at 140℃ for 10s), and after winding, obtain patterned ultrathin copper foil with carrier.

[0084] Based on the above preparation process, a patterned ultrathin copper foil product with a carrier is obtained. The ultrathin copper layer is only 1μm thick, and with a 35μm carrier layer, the product exhibits excellent bending performance. Under flexible bending with a radius of curvature of 0.5mm, the change rate of circuit resistance is ≤5%. The resistance of the composite conductive layer is minimally affected by temperature (resistance change rate ≤10% within the range of -40℃ to 85℃), ensuring uniform current distribution and stable circuit conductivity during the electroplating process of the ultrathin copper layer.

[0085] In another preferred embodiment: a design that matches a high-thickness insulating layer with an ultra-thin copper layer; The structure and parameters of patterned ultrathin copper foil products with carriers include: Carrier layer: 25μm electrolytic copper foil with a surface roughness Rz=1.3μm, which has undergone stress relief treatment to prevent the copper foil from warping during subsequent processing. Peel-off layer: Conductive layer: made of polypyrrole, 1.0 μm thick. Parameters are strictly controlled during electrodeposition to ensure uniform thickness (deviation ≤ ±0.05 μm) and conductivity meets the requirements of high-current electroplating (maximum allowable current density ≥ 0.1 mA / cm²). Insulating layer: photosensitive PI film, 5μm thick, prepared by mask exposure + alkaline development, pattern line width / line spacing = 5μm / 5μm, the bonding force between the insulating layer and the conductive layer is ≥0.9N / mm, and it has excellent chemical corrosion resistance (no dissolution or peeling after immersion in 20% sulfuric acid solution for 24h). Ultra-thin copper layer: 5μm thick, perfectly matching the thickness of the insulation layer, surface roughness Rz=1.4μm, circuit pattern accuracy ±0.3μm, copper layer hardness HV=120, good wear resistance (after 100 friction tests, wear amount ≤0.1μm).

[0086] The patterned ultrathin copper foil product with carrier provided in this embodiment has an insulating layer and an ultrathin copper layer both of 5μm thick, avoiding stress concentration during lamination due to thickness differences. The resulting product exhibits excellent flatness (warpage ≤0.5mm / m). The ultrathin copper layer has high hardness and good wear resistance, minimizing damage to the circuitry during subsequent PCB processing (drilling, cutting), thus improving product yield to over 95%. It can be used for inner layer circuitry fabrication in multilayer PCBs. The insulating layer's temperature resistance (long-term operating temperature ≥200℃) meets the requirements of multilayer board lamination processes, and the signal transmission delay is ≤1ns / m.

[0087] Although exemplary embodiments have been described herein with reference to the accompanying drawings, it should be understood that the above exemplary embodiments are merely illustrative and are not intended to limit the scope of the invention. Various changes and modifications can be made therein by those skilled in the art without departing from the scope and spirit of the invention. All such changes and modifications are intended to be included within the scope of the invention as claimed in the appended claims.

[0088] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0089] Although the description of the invention has been given in conjunction with the specific embodiments described above, it will be apparent to those skilled in the art that many substitutions, modifications, and variations can be made based on the foregoing. Therefore, all such substitutions, modifications, and variations are included within the spirit and scope of the appended claims.

Claims

1. A method for preparing patterned ultrathin copper foil with a carrier, characterized in that, include: Step 1: Pre-treat the carrier copper foil, wherein the carrier copper foil is an electrolytic copper foil with a thickness of 9-35μm; Step 2: Immerse the pretreated carrier copper foil in the electrodeposition solution and perform electrodeposition to obtain a carrier copper foil containing a conductive layer; the electrodeposition solution is a solution containing a conductive polymer prepolymer or a phosphoric acid solution containing pyrrole. Step 3: Apply a PI film to the surface of the conductive layer, and complete the patterning of the insulating layer by direct writing with ultraviolet laser or by exposure through a mask and alkaline development. Step 4: Electroplating copper in the exposed areas of the conductive layer using an electrolyte solution; Step 5: Perform surface treatment on the conductive layer after copper electroplating to obtain patterned ultrathin copper foil with carrier.

2. The method for preparing patterned ultrathin copper foil with a carrier according to claim 1, characterized in that, Step 1 includes: The carrier copper foil is placed in an acid pickling solution to remove the oxide layer; The pickling solution used is a sulfuric acid aqueous solution with a concentration of 140-150 g / L; the pickling temperature is 34-40℃; and the pickling time is 10-20 s.

3. The method for preparing patterned ultrathin copper foil with a carrier according to claim 2, characterized in that, Step 2 includes: The concentration of pyrrole in the phosphoric acid solution is 0.2-0.5 mol / L; the concentration of phosphoric acid is 0.4-1.0 mol / L.

4. The method for preparing patterned ultrathin copper foil with a carrier according to claim 3, characterized in that, Step 2 includes: The current density for electrodeposition is 0.03-0.09 mA / cm²; the electrodeposition time is 0.5 min-12 min.

5. The method for preparing patterned ultrathin copper foil with a carrier according to claim 4, characterized in that, Step 3 includes: Ultraviolet laser direct writing uses a laser with a wavelength of 355nm and an accuracy of ±2μm; The dimensions of the pattern features formed after the insulating layer patterning process are line width / line spacing = 5μm / 5μm.

6. The method for preparing patterned ultrathin copper foil with a carrier according to claim 5, characterized in that, Step 4 includes: The electrolyte contains 70-80 g / L copper ions, 90-110 g / L sulfuric acid, 10.0-20.0 mg / L sodium didithiopropane sulfonate, 5.0-10.0 mg / L hydroxyethyl cellulose, 15.0-30.0 mg / L polyethylene glycol, and 10.0-20.0 mg / L hydrolyzed collagen. Electrolysis conditions: current density 54-64 A / m 2 The electrolyte flow rate is 30-35m³. 3 / h, the temperature of the electrolyte is 40-42℃.

7. The method for preparing patterned ultrathin copper foil with a carrier according to claim 6, characterized in that, Step 5 includes: Step 5.1: Pickling; wherein the pickling solution contains a sulfuric acid aqueous solution with a concentration of 140-150 g / L, and the pickling temperature is 34-40℃; Step 5.2: Roughening; The concentration of copper ions in the roughening solution is 12-14 g / L, the concentration of sulfuric acid is 120-130 g / L, the concentration of sodium tungstate is 60-80 mg / L, and the temperature of the roughening solution is 30-35℃; Step 5.3: Curing; The copper concentration in the curing tank is 50-56 g / L, the sulfuric acid concentration is 90-120 g / L, and the temperature is 40-46℃; Step 5.4: One water wash; use ultrapure water, temperature 25-35℃, pH 6.8-7.2; Step 5.5: Anti-oxidation treatment; The concentration of nickel ions in the anti-oxidation treatment tank is 1.5-2.5 g / L, the concentration of zinc ions is 3.5-4.5 g / L, the concentration of K4P2O7 is 70-100 g / L, the pH value is 10-11, and the temperature is 25-35℃. Step 5.6: Secondary water wash; use ultrapure water, temperature 25-35℃, pH 6.8-7.2; Step 5.7: Silanization; Spraying an organosilane coupling agent; The concentration of the organosilane coupling agent is 1.0-1.5 g / L, the pH is 9-12, and the temperature is 25-35℃; Step 5.8: Drying; the drying temperature is 130-140℃, and the time is 5-10 seconds; Step 5.9: Rewinding; After rewinding, a patterned ultrathin copper foil with a carrier is obtained.

8. A patterned ultrathin copper foil with a carrier, characterized in that, The ultrathin copper foil is prepared by a patterned ultrathin copper foil preparation method with a carrier as described in any one of claims 1-7, wherein the ultrathin copper foil comprises: a carrier layer, a release layer and an ultrathin copper layer; The carrier copper foil is an electrolytic copper foil with a thickness of 9-35 μm; the surface roughness Rz of the carrier layer is ≤1.5 μm; The release layer consists of a conductive layer and an insulating layer from bottom to top; The conductive layer is made of polyaniline and / or polypyrrole conductive polymer, with a thickness of 0.01-1 μm; the insulating layer and the ultrathin copper layer are both 1-5 μm thick.

9. The patterned ultrathin copper foil with a carrier according to claim 8, characterized in that, The insulating layer is prepared by mechanical or laser processing of polyimide PI, or by photosensitive polybenzoxazole PBO film photomask; The pattern of the insulating layer is the opposite of the desired copper circuit pattern.

10. The patterned ultrathin copper foil with a carrier according to claim 9, characterized in that, The surface roughness Rz of the ultrathin copper laminate is ≤1.5μm.

Images