Design of flow mode of plating solution for large-area chemical plating uniform nickel-phosphorus alloy resistive film

Abstract

The invention provides a plating solution flow mode design for a large-area chemical plating uniform nickel-phosphorus alloy resistive film, which comprises a chemical plating solution additive formula, a plating bath design and plating solution flow process parameters, and aims to improve the stability of the plating solution and reduce the surface tension of the plating solution, thereby improving the resistance uniformity of the nickel-phosphorus alloy resistive film. The method is suitable for aerospace, electronic circuit and other industries.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of printed circuit board, in particular to a large-area chemical plating uniform nickel-phosphorus alloy resistance film plating solution flow mode design, which is suitable for the printed board electronic circuit industry. BACKGROUND

[0002] In the development process of human society in the 21st century, the electronic industry has become the core pillar industry of the information age, and its related technologies continue to occupy the forefront of technological development. Current and future major product innovations are deeply dependent on electronic technology breakthroughs, which has made the electronic manufacturing industry and technology a leader in the modern industrial system. As a basic carrier in this field, printed circuit boards (PCB) or printed wiring boards (PWB) are composite materials formed through electronic printing technology processes, and their main function is to provide a reliable mounting substrate and electrical interconnection platform for electronic components or functional modules. Embedded resistance technology effectively saves surface space and improves the density of electronic packaging by integrating resistance directly into the PCB substrate.

[0003] Nickel-phosphorus alloy, with its excellent resistance stability, chemical inertness, and mechanical flexibility, has become a key material for applications in multiple fields and can be prepared by chemical plating, magnetron sputtering, and evaporation. However, the resistance value error of nickel-phosphorus alloy resistance films prepared by sputtering method often exceeds 15%, which cannot meet the production standards of high-precision resistors. Overall, the current process for manufacturing nickel-phosphorus alloy resistance films still faces significant challenges in cost control, equipment complexity, and resistance uniformity. Compared to magnetron sputtering technology, chemical plating exhibits unique advantages: it does not require an external power source and relies on a self-catalytic reaction. This method effectively reduces production costs, improves processing efficiency, and better controls the precision and consistency of resistance values, thereby meeting market requirements for electronic devices. However, the chemical plating process itself is not perfect. If the solution composition in the plating tank is not evenly distributed (local concentration difference) or the key process parameters are not set reasonably, it may lead to fluctuations in the thickness and composition of the final formed nickel-phosphorus alloy film, directly affecting the uniformity of the plating layer and thus damaging the uniformity of resistance performance. SUMMARY

[0004] The present application provides a large-area chemical plating uniform nickel-phosphorus alloy resistance film plating solution flow mode design, which includes chemical plating solution additive formulation, plating tank design, and plating solution flow process parameters, aiming to improve the stability of the plating solution and reduce the surface tension of the plating solution, thereby improving the performance of the nickel-phosphorus alloy plating layer and enhancing uniformity.

[0005] (1) Chemical plating solution additive formulation: aminoacetic acid, potassium perfluorohexane-1-sulfonate, and polyvinylpyrrolidone (PVP-30);

[0006] (2) After dissolving the chemical plating additives, add the nickel source, reducing agent, and stabilizer, adjust the pH value and temperature of the plating solution, and suspend the copper-clad glass plate in the plating solution.

[0007] (3) The outlet is located at the bottom of the plating tank. The plating solution enters the heating tank through the outlet and is then pumped back into the plating tank by a pump. The plating tank is designed with a symmetrical double-layer inlet, with each layer containing 21 small holes.

[0008] Preferably, in step 1, the concentration of glycine is 5 g / L-15 g / L, the concentration of potassium perfluorohexane-1-sulfonate is 0.01 g / L-0.05 g / L, and the concentration of polyvinylpyrrolidone is 0.01 g / L-0.05 g / L.

[0009] Preferably, in step 2, the nickel source is provided by nickel sulfate, hypophosphite is used as a reducing agent and serves as both a phosphorus and nickel source, lead acetate is used as a stabilizer, the electroless plating temperature is 85 ℃, the electroless plating time is 50 s, and ammonia water is used to adjust the pH to 4.0. The copper-clad glass plate is 15 cm from the bottom, the glass substrate area is 68 cm × 80 cm, the copper foil area is 64 cm × 76 cm, the electroplating adhesive band is 5 cm wide, and the electroless plating area is 58 cm × 70 cm.

[0010] Preferably, in step 3, the bottom outlet diameter is 4 cm, the inlet orifice diameter is 0.5 cm, and the spacing is 4 cm. The double-layer outlets are 22 cm and 28 cm away from the bottom, respectively. The circulation flow rate is 20 L / min-40 L / min, and the plating tank material is stainless steel.

[0011] The beneficial effects of this invention are: by ensuring that the nickel-phosphorus alloy coating is in a high phosphorus state, this invention greatly reduces the surface tension of the industrial-scale electroplating solution, reduces the uniformity reduction caused by hydrogen evolution, and improves the overall quality of the coating.

[0012] The chemical plating high-phosphorus nickel-phosphorus alloy formula disclosed in this invention aims to improve the uniformity of the nickel-phosphorus alloy resistive film in the chemical plating industry, with low cost, and is suitable for industries such as aerospace and electronic circuits. Attached Figure Description

[0013] Figure 1 SEM image of the electroless nickel-phosphorus alloy resistive film;

[0014] Figure 2 3D design of the inlet hole for a large-area electroless nickel-phosphorus alloy plating tank;

[0015] Figure 3 3D diagram of the overall device for electroless plating of large-area nickel-phosphorus alloy;

[0016] Figure 4 This is a process flow diagram for electroless plating of large-area nickel-phosphorus alloy resistive films. Detailed Implementation

[0017] The present invention can also be implemented or applied through various differentiated technical solutions, as illustrated in the following examples and accompanying drawings. The technical details contained in this specification can be modified or adapted to different technical perspectives and application requirements without departing from the technical concept of the present invention.

[0018] Example 1

[0019] Step 1: Preparation of chemical plating solution, including the following concentrations of each component: nickel sulfate 42 g / L, sodium hypophosphite 23 g / L, lead acetate 1 mg / L, glycine 10 g / L, potassium perfluorohexane-1-sulfonate 0.02 g / L, polyvinylpyrrolidone 0.02 g / L, and ammonia water to adjust the pH to 4.0.

[0020] Step 2: Immerse the copper-clad glass substrate in alkaline solution for 15 minutes. After the grease is dissolved, clean it with ultrapure water. Then immerse it in an 8% dilute sulfuric acid solution for 15 minutes. After activation, clean it with ultrapure water.

[0021] Step 3: The electroless plating reaction is initiated by constant current, with the plating solution temperature at 85 ℃ and the circulation flow rate at 25 L / min.

[0022] Step 4: Wash the copper foil with water, rinse with 8% dilute sulfuric acid, and wash with water in sequence. After completion, place it in a vacuum drying oven for 12 hours, and keep the oven temperature at 60 ℃.

[0023] Step 5: Place the copper foil with resistance coating into the laminator. The nickel-phosphorus plating layer is placed directly onto the FR4 prepreg and vacuum high-temperature lamination is performed. During this process, the FR4 melts and is completely cured onto the nickel-phosphorus alloy plating layer.

[0024] Step 6: After lamination, use an alkaline etching solution to remove the copper foil substrate, leaving the nickel-phosphorus alloy plating layer. Then, place it in an oven to dry at 60 ℃ for 6 hours.

[0025] The sheet resistance of the coating was measured and calculated using an RTS-8 four-probe tester. The average sheet resistance of the nickel-phosphorus alloy resistive film was 54.3 Ω / sq, and the non-uniformity was 16%.

[0026] Example 2

[0027] Step 1: Preparation of the chemical plating solution, including the following concentrations of each component: nickel sulfate 42 g / L, sodium hypophosphite 23 g / L, lead acetate 1 mg / L, glycine 5 g / L, potassium perfluorohexane-1-sulfonate 0.01 g / L, polyvinylpyrrolidone 0.03 g / L, and ammonia water to adjust the pH to 4.0.

[0028] Step 2: Immerse the copper-clad glass substrate in alkaline solution for 15 minutes. After the grease is dissolved, clean it with ultrapure water. Then immerse it in an 8% dilute sulfuric acid solution for 15 minutes. After activation, clean it with ultrapure water.

[0029] Step 3: The electroless plating reaction is initiated by constant current, with the plating solution temperature at 85 ℃ and the circulation flow rate at 35 L / min.

[0030] Step 4: Wash the copper foil with water, rinse with 8% dilute sulfuric acid, and wash with water in sequence. After completion, place it in a vacuum drying oven for 12 hours, and keep the oven temperature at 60 ℃.

[0031] Step 5: Place the copper foil with resistance coating into the laminator. The nickel-phosphorus plating layer is placed directly onto the FR4 prepreg and vacuum high-temperature lamination is performed. During this process, the FR4 melts and is completely cured onto the nickel-phosphorus alloy plating layer.

[0032] Step 6: After lamination, use an alkaline etching solution to remove the copper foil substrate, leaving the nickel-phosphorus alloy plating layer. Then, place it in an oven to dry at 60 ℃ for 6 hours.

[0033] The sheet resistance of the coating was measured and calculated using an RTS-8 four-probe tester. The average sheet resistance of the nickel-phosphorus alloy resistive film was 49.6 Ω / sq, and the non-uniformity was 23%.

[0034] Example 3

[0035] Step 1: Preparation of chemical plating solution, including the following concentrations of each component: nickel sulfate 42 g / L, sodium hypophosphite 23 g / L, lead acetate 1 mg / L, glycine 15 g / L, potassium perfluorohexane-1-sulfonate 0.04 g / L, polyvinylpyrrolidone 0.01 g / L, and ammonia water to adjust the pH to 4.0.

[0036] Step 2: Immerse the copper-clad glass substrate in alkaline solution for 15 minutes. After the grease is dissolved, clean it with ultrapure water. Then immerse it in an 8% dilute sulfuric acid solution for 15 minutes. After activation, clean it with ultrapure water.

[0037] Step 3: The electroless plating reaction is initiated by constant current, with the plating solution temperature at 85 ℃ and the circulation flow rate at 30 L / min.

[0038] Step 4: Wash the copper foil with water, rinse with 8% dilute sulfuric acid, and wash with water in sequence. After completion, place it in a vacuum drying oven for 12 hours, and keep the oven temperature at 60 ℃.

[0039] Step 5: Place the copper foil with resistance coating into the laminator. The nickel-phosphorus plating layer is placed directly onto the FR4 prepreg and vacuum high-temperature lamination is performed. During this process, the FR4 melts and is completely cured onto the nickel-phosphorus alloy plating layer.

[0040] Step 6: After lamination, use an alkaline etching solution to remove the copper foil substrate, leaving the nickel-phosphorus alloy plating layer. Then, place it in an oven to dry at 60 ℃ for 6 hours.

[0041] The sheet resistance of the coating was measured and calculated using an RTS-8 four-probe tester. The average sheet resistance of the nickel-phosphorus alloy resistive film was 51.6 Ω / sq, and the non-uniformity was 19%.

Claims

1. A design for the flow pattern of a large-area electroless uniform nickel-phosphorus alloy resistive thin film plating solution, characterized in that, The method includes the following steps: Step 1, Formulation of additives for chemical plating solution: glycine, potassium perfluorohexane-1-sulfonate, polyvinylpyrrolidone (PVP-30). Step 2: After dissolving the chemical plating additives, add the nickel source, reducing agent, and stabilizer, adjust the pH and temperature of the plating solution, and suspend the copper-clad glass plate in the plating solution. Step 3: The outlet is set at the bottom of the plating tank. The plating solution enters the heating tank through the outlet and is then pumped back into the plating tank by a pump. The plating tank has a symmetrical double-layer liquid inlet design, with each layer containing 21 small holes.

2. The formulation of the chemical plating additive as described in claim 1 is characterized by... The concentrations of glycine were 5 g / L to 15 g / L, potassium perfluorohexane-1-sulfonate were 0.01 g / L to 0.05 g / L, and polyvinylpyrrolidone were 0.01 g / L to 0.05 g / L.

3. The nickel source and reducing agent in the electroless plating solution as described in claim 1, characterized in that, It consists of nickel sulfate, which provides the nickel source; hypophosphite, which acts as the phosphorus source and reducing agent; and lead acetate, which acts as the stabilizer. The electroless plating temperature is 85 °C, and the pH value is 4.

0.

4. As described in claim 1, the copper-clad glass plate is 15 cm from the bottom, the glass substrate area is 68 cm × 80 cm, the copper foil area is 64 cm × 76 cm, the electroplating adhesive band is 5 cm wide, and the chemical plating area is 58 cm × 70 cm.

5. The double-layered liquid inlets as described in claim 1 are respectively 22 cm and 28 cm from the bottom.

6. As described in claim 1, each layer is provided with 21 liquid inlet holes, with a hole diameter of 0.5 cm and a spacing of 4 cm.

7. The pump circulation flow rate as described in claim 1 is 20 L / min-40 L / min.

Images