Automatic analysis and control method for electroplating nickel-phosphorus alloy

Abstract

The invention discloses an automatic analysis and control method for electroplating nickel-phosphorus alloy, which relates to the field of electroplating technology, and includes step S10: an automatic analysis system calculates the sodium citrate concentration of a nickel-phosphorus alloy solution, uses a sampling metering pump to sample the nickel-phosphorus alloy solution, uses an ultrapure water metering pump to dilute the nickel-phosphorus alloy solution, uses a sulfuric acid metering pump to extract dilute sulfuric acid to provide an acidic environment, uses a cerium sulfate metering pump to add excess cerium sulfate to react with sodium citrate, uses an ammonium ferrous sulfate metering pump to back-titrate the remaining cerium sulfate, calculates the sodium citrate concentration according to the consumption of ammonium ferrous sulfate, and uses a pH meter to measure the pH value of the nickel-phosphorus alloy solution; step S20: the difference between the sodium citrate concentration calculated by the automatic replenishment system and the control lower limit is used to calculate the automatic replenishment amount, automatically replenishes sodium citrate, replenishes sulfuric acid according to the pH value of the nickel-phosphorus alloy solution, and replenishes the phosphorus content additive according to the ampere-hour. The present invention can automatically replenish the components in the nickel-phosphorus alloy solution.

Description

Technical Field

[0001] The invention relates to the technical field of electroplating, in particular to an automatic analysis and control method for electroplating nickel-phosphorus alloy. Background Art

[0002] Electroplating is a common surface treatment method, and the maintenance of the plating solution is particularly important. Nickel-phosphorus alloy solution is one of the plating solutions with excellent performance. The composition of the plating solution is uniform, the fluctuation is small, and the pH is stable.

[0003] The nickel-phosphorus alloy solution contains nickel salt, sodium citrate and phosphorus content additives. During electroplating, the nickel rod acts as an anode and dissolves into nickel ions into the plating solution. Therefore, the concentration of nickel salt in the plating solution will not decrease, but only the sodium citrate and phosphorus content additives will decrease. Currently, the manufacturers of nickel-phosphorus alloy solutions often use manual weekly sampling and analysis or daily sampling and analysis, and then centrally add sodium citrate and phosphorus content additives. This analysis and addition method has disadvantages. The composition of the plating solution just added is quite different from that before the next sampling and testing, which will lead to poor uniformity of the plated products, making it difficult to guarantee the quality of the products produced. Summary of the invention

[0004] The purpose of the present invention is to provide an automatic analysis and control method for electroplating nickel-phosphorus alloy, which can automatically replenish the components in the nickel-phosphorus alloy solution and eliminate the difference in the components of the nickel-phosphorus alloy solution just replenished and before the next sampling and testing.

[0005] To achieve the above object, the solution of the present invention is:

[0006] An automatic analysis and control method for electroplating nickel-phosphorus alloy, involving an automatic analysis system and an automatic replenishment system, comprises the following steps:

[0007] Step S10: the automatic analysis system calculates the concentration of sodium citrate in the nickel-phosphorus alloy solution, samples the nickel-phosphorus alloy solution using a sampling metering pump, dilutes the nickel-phosphorus alloy solution with ultrapure water using an ultrapure water metering pump, extracts dilute sulfuric acid using a sulfuric acid metering pump and adds it to the diluted nickel-phosphorus alloy solution to provide an acidic environment for the cerium sulfate reaction, adds excess cerium sulfate to react with sodium citrate using a cerium sulfate metering pump, back-titrates the remaining cerium sulfate using an ammonium ferrous sulfate metering pump, and uses a potentiometric titrator to detect potential changes to determine the titration endpoint, calculates the sodium citrate concentration based on the ammonium ferrous sulfate consumption, and measures the pH value of the nickel-phosphorus alloy solution using a pH meter;

[0008] Step S20: The automatic replenishment system calculates the automatic replenishment amount according to the difference between the calculated sodium citrate concentration and the control lower limit, and then automatically replenishes sodium citrate, and also automatically adds 10% sulfuric acid according to the pH value of the nickel-phosphorus alloy solution, and also replenishes the phosphorus content additive according to the ampere-hour, so as to control the sodium citrate concentration, pH value and phosphorus content within the control lower limit.

[0009] Furthermore, in step S10, the automatic analysis system also draws nickel-phosphorus alloy solution through a sampling pump and inputs it into the nickel ion sensor. The nickel ion sensor analyzes the concentration of nickel ions, and calculates the concentration of nickel salt based on the concentration of nickel ions. The nickel salt is used to monitor the stability of the nickel-phosphorus alloy solution in the electroplating equipment, and when the nickel salt concentration in the nickel-phosphorus alloy solution is lower than the set threshold, the electroplating equipment will issue an early warning.

[0010] Furthermore, in step S10, when the nickel-phosphorus alloy solution is diluted with ultrapure water, the mass ratio of the nickel-phosphorus alloy solution to the ultrapure water is 1:2.

[0011] Further, the reaction principle in step S10 is:

[0012] (1) The tetravalent cerium ion first reacts with the citrate ion to generate carbon dioxide which consumes the sampled citric acid. The reaction time is greater than or equal to 40 minutes. The ion reaction equation is:

[0013] 5H2O+18Ce 4+ +(C6H507) 3- →18Ce 3+ +6CO2↑+15H + ;

[0014] (2) Use ammonium ferrous sulfate to back titrate and determine the remaining tetravalent cerium ions. The ion reaction equation involved is:

[0015] Fe 2+ +Ce 4+ →Ce 3+ +Fe 3+ .

[0016] Furthermore, in step S10, when cerium sulfate reacts with sodium citrate and when ammonium ferrous sulfate reacts with cerium sulfate, the periphery of the reaction kettle is wrapped with a micro electric blanket.

[0017] Furthermore, after step S10, a cleaning step is provided, in which pure water is added into the reactor using a pure water pump, and stirred using a magnetic stirrer under the reactor. After cleaning, waste water is discharged using a waste pump, and cleaning is performed 2-3 times before waiting for the next sampling and analysis.

[0018] Further, in step S20, 1 ml of phosphorus content additive is supplemented at 1 ampere-hour, and the phosphorus content additive is supplemented once at 1000 ampere-hours.

[0019] Furthermore, in step S20, the automatic replenishing system also automatically replenishes brightener, and the brightener and sodium citrate are replenished together, and the mass ratio of sodium citrate to brightener is 1:0.75.

[0020] Furthermore, the phosphorus content additive is a solution containing orthophosphate ions and sodium hypophosphite.

[0021] After adopting the above scheme, the beneficial effects of the present invention are:

[0022] The invention calculates the concentration and pH value of sodium citrate in the nickel-phosphorus alloy solution through an automatic analysis system, and the automatic supplement system automatically supplements sodium citrate and 10% sulfuric acid according to the sodium citrate concentration and pH value determined by the automatic analysis system, and is also used to supplement the phosphorus content additive according to the ampere-hour, so as to control the sodium citrate, the pH value and the phosphorus content within the control lower limit, eliminate the difference in the components of the nickel-phosphorus alloy solution just supplemented and before the next sampling and testing, and enable the invention to comprehensively monitor the nickel-phosphorus alloy solution without manual sampling and analysis, with a higher analysis frequency, and to supplement components in small amounts and multiple times, so that the nickel-phosphorus alloy solution in each time period maintains good consistency, so that the electroplated product has good uniformity. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a flow chart of the present invention. DETAILED DESCRIPTION

[0024] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0025] like Figure 1 As shown, this embodiment provides an automatic analysis control method for electroplating nickel-phosphorus alloy, involving an automatic analysis system and an automatic replenishment system, including the following steps:

[0026] Step S10: the automatic analysis system calculates the concentration of sodium citrate in the nickel-phosphorus alloy solution, samples the nickel-phosphorus alloy solution using a sampling metering pump, dilutes the nickel-phosphorus alloy solution with ultrapure water using an ultrapure water metering pump, extracts dilute sulfuric acid using a sulfuric acid metering pump and adds it to the diluted nickel-phosphorus alloy solution to provide an acidic environment for the cerium sulfate reaction, adds excess cerium sulfate to react with sodium citrate using a cerium sulfate metering pump, titrates the remaining cerium sulfate using an ammonium ferrous sulfate metering pump, and uses a potentiometric titrator to detect potential changes to determine the titration end point, calculates the sodium citrate concentration based on the ammonium ferrous sulfate consumption, and measures the pH value of the nickel-phosphorus alloy solution using a pH meter;

[0027] Step S20: the automatic replenishment system calculates the automatic replenishment amount according to the difference between the calculated sodium citrate concentration and the control lower limit, and then automatically replenishes sodium citrate, and also automatically replenishes 10% sulfuric acid according to the pH value of the nickel-phosphorus alloy solution, and also replenishes the phosphorus content additive according to the ampere-hour, so as to control the sodium citrate concentration, pH value and phosphorus content within the control lower limit;

[0028] The invention calculates the concentration and pH value of sodium citrate in the nickel-phosphorus alloy solution through an automatic analysis system, and the automatic supplement system automatically supplements sodium citrate and 10% sulfuric acid according to the sodium citrate concentration and pH value determined by the automatic analysis system, and is also used to supplement the phosphorus content additive according to the ampere-hour, so as to control the sodium citrate, pH value and phosphorus content within the control lower limit, eliminate the difference in the components of the nickel-phosphorus alloy solution just supplemented and before the next sampling and testing, and the invention can also comprehensively monitor the nickel-phosphorus alloy solution without manual sampling and analysis, the analysis frequency is higher, and the supplemented components can be added in small amounts and multiple times, so that the nickel-phosphorus alloy solution in each time period maintains good consistency, so that the electroplated product has good uniformity.

[0029] Specifically, a sampling metering pump, an ultrapure water metering pump, a sulfuric acid metering pump, a cerium sulfate metering pump, and an ammonium ferrous sulfate metering pump are used to ensure that the added amount is accurate.

[0030] Specifically, in step S10, the automatic analysis system also extracts the nickel-phosphorus alloy solution through a sampling pump and inputs it into the nickel ion sensor. The nickel ion sensor analyzes the concentration of nickel ions, and calculates the concentration of nickel salt based on the concentration of nickel ions. The nickel salt is used to monitor the stability of the nickel-phosphorus alloy solution in the electroplating equipment, and when the concentration of nickel salt in the nickel-phosphorus alloy solution is lower than the set threshold, the electroplating equipment will issue an early warning. Specifically, the nickel salt in this embodiment is nickel sulfate, and the concentration of nickel sulfate is calculated based on the concentration of nickel ions. It can be understood that the method of calculating nickel sulfate based on the concentration of nickel ions is a prior art and will not be elaborated here.

[0031] Preferably, in step S10, when the nickel-phosphorus alloy solution is diluted with ultrapure water, the mass ratio of the nickel-phosphorus alloy solution to the ultrapure water is 1:2.

[0032] Specifically, the reaction principle in step S10 is:

[0033] (1) The tetravalent cerium ion first reacts with the citrate ion to generate carbon dioxide which consumes the sampled citric acid. The reaction time is greater than or equal to 40 minutes. The ion reaction equation is:

[0034] 5H2O+18Ce 4+ +(C6H507) 3- →18Ce 3+ +6CO2↑+15H + ;

[0035] (2) Use ammonium ferrous sulfate to back titrate and determine the remaining tetravalent cerium ions. The ion reaction equation involved is:

[0036] Fe 2+ +Ce 4+ →Ce 3+ +Fe 3+ ;

[0037] Among them, the divalent ferrous ion is reducing, cerium is a rare earth element, and is at the highest valence: +4, which is oxidizing. The other valence state of cerium is +3. Therefore, in this reaction, Fe2+ is oxidized and Ce4+ is reduced, and a redox reaction occurs.

[0038] In step S10, when cerium sulfate reacts with sodium citrate and when ammonium ferrous sulfate reacts with cerium sulfate, the periphery of the reaction kettle is wrapped with a micro electric heating blanket to maintain the same temperature as the nickel-phosphorus alloy solution to achieve analysis accuracy.

[0039] After step S10, a cleaning step is also provided, in which pure water is added into the reactor using a pure water pump, and stirred using a magnetic stirrer under the reactor to make the cleaning more thorough. After the cleaning is completed, the waste water is discharged using a waste pump, and the cleaning is repeated 2-3 times, waiting for the next sampling and analysis.

[0040] Further, in step S20, 1 ml of phosphorus content additive is supplemented at 1 ampere-hour, and the phosphorus content additive is supplemented once at 1000 ampere-hours.

[0041] In step S20, the automatic replenishing system also automatically replenishes brightener, and the brightener and sodium citrate are replenished together, and the mass ratio of sodium citrate to brightener is 1:0.75.

[0042] Specifically, the phosphorus content additive is a solution containing orthophosphate ions and sodium hypophosphite.

[0043]

[0044] Table 1: Data of nickel-phosphorus alloy solution under the control of automatic analysis system and automatic addition system

[0045]

[0046] Table 2: Data of nickel-phosphorus alloy solution under manual analysis control

[0047] By comparing Table 1 and Table 2, the standard deviation of the nickel-phosphorus alloy solution under the control of the automatic analysis system and the automatic replenishment system is significantly lower than the standard deviation of the nickel-phosphorus alloy solution under the control of manual analysis.

[0048] The above description is only a preferred embodiment of the present invention and is not a limitation on the design of this case. Any equivalent changes made based on the design key of this case shall fall within the protection scope of this case.

Claims

1. An automatic analysis and control method for electroplating nickel-phosphorus alloy, involving an automatic analysis system and an automatic replenishment system, characterized in that: The following steps are involved: step S10: The automatic analysis system calculates the concentration of sodium citrate in the nickel-phosphorus alloy solution, samples the nickel-phosphorus alloy solution using a sampling metering pump, dilutes the nickel-phosphorus alloy solution with ultrapure water using an ultrapure water metering pump, extracts dilute sulfuric acid using a sulfuric acid metering pump and adds it to the diluted nickel-phosphorus alloy solution to provide an acidic environment for the cerium sulfate reaction, adds excess cerium sulfate to react with sodium citrate using a cerium sulfate metering pump, back-titrates the remaining cerium sulfate using an ammonium ferrous sulfate metering pump, and uses a potentiometric titrator to detect the potential change to determine the titration end point, calculates the sodium citrate concentration based on the ammonium ferrous sulfate consumption, and measures the pH value of the nickel-phosphorus alloy solution using a pH meter; Step S20: the automatic replenishment system calculates the automatic replenishment amount according to the difference between the calculated sodium citrate concentration and the control lower limit, and then automatically replenishes sodium citrate, and also automatically replenishes 10% sulfuric acid according to the pH value of the nickel-phosphorus alloy solution, and also replenishes the phosphorus content additive according to the ampere-hour, so as to control the sodium citrate concentration, pH value and phosphorus content within the control lower limit; The reaction principle in step S10 is: (1) The tetravalent cerium ion first reacts with the citrate ion to generate carbon dioxide which consumes the sampled citric acid. The reaction time is greater than or equal to 40 minutes. The ion reaction equation is: 5H2O+18Ce 4+ +(C6H507) 3- →18Ce 3+ +6CO2↑+15H + ; (2) Use ammonium ferrous sulfate to back titrate and determine the remaining tetravalent cerium ions. The ion reaction equation involved is: Fe 2+ +What 4+ →What 3+ +Fe 3+ 。 2. The automatic analysis and control method for electroplating nickel-phosphorus alloy according to claim 1, characterized in that: In step S10, the automatic analysis system also draws the nickel-phosphorus alloy solution through a sampling pump and inputs it into the nickel ion sensor. The nickel ion sensor analyzes the concentration of nickel ions and calculates the concentration of nickel salt based on the concentration of nickel ions. The nickel salt is used to monitor the stability of the nickel-phosphorus alloy solution in the electroplating equipment. When the nickel salt concentration in the nickel-phosphorus alloy solution is lower than the set threshold, the electroplating equipment will issue an early warning.

3. The automatic analysis and control method for electroplating nickel-phosphorus alloy according to claim 1, characterized in that: In step S10, when the nickel-phosphorus alloy solution is diluted with ultrapure water, the mass ratio of the nickel-phosphorus alloy solution to the ultrapure water is 1:

2.

4. The automatic analysis and control method for electroplating nickel-phosphorus alloy according to claim 1, characterized in that: In step S10, when cerium sulfate reacts with sodium citrate and when ammonium ferrous sulfate reacts with cerium sulfate, the periphery of the reaction kettle is wrapped with a micro electric heating blanket.

5. The automatic analysis and control method for electroplating nickel-phosphorus alloy according to claim 1, characterized in that: After step S10, a cleaning step is also provided, in which pure water is added into the reactor using a pure water pump, and stirred using a magnetic stirrer under the reactor. After cleaning, waste water is discharged using a waste pump, and cleaning is performed 2-3 times before waiting for the next sampling analysis.

6. The automatic analysis and control method for electroplating nickel-phosphorus alloy according to claim 1, characterized in that: In step S20, 1 ml of phosphorus content additive is added at 1 ampere-hour, and the phosphorus content additive is added once at 1000 ampere-hours.

7. The automatic analysis and control method for electroplating nickel-phosphorus alloy according to claim 1, characterized in that: In step S20, the automatic replenishing system also automatically replenishes brightener, and the brightener and sodium citrate are replenished together, and the mass ratio of sodium citrate to brightener is 1:0.

75.

8. The automatic analysis and control method for electroplating nickel-phosphorus alloy according to claim 1, characterized in that: Phosphorus content additives are solutions containing orthophosphate ions and sodium hypophosphite solutions.

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