CN114457325B - Nickel layer thickness control method for nickel-plated high polymer microspheres - Google Patents

Abstract

The invention discloses a nickel layer thickness control method of nickel plating polymer microspheres, which comprises the following steps: coarsening the polymer microsphere, treating the surface of the roughened polymer microsphere, plating nickel on the surface of the activated polymer microsphere by a batch plating method, and plating nickel on the surface of the batch nickel-plated microsphere by a continuous plating method. The technical means of the invention is embodied in the chemical nickel plating stage, the chemical nickel plating layer with controllable thickness, uniformity, compactness and strong binding force is obtained by controlling the supplementing times and the separating and continuing times of the nickel plating solution by adopting a method of batch plating and continuing plating, and the chemical nickel plating method has simple process, safety and environmental protection, and the obtained nickel layer has high reliability and wide application prospect.

Description

Nickel layer thickness control method for nickel-plated high polymer microspheres

Technical Field

The invention relates to the technical field of high polymer materials, in particular to a nickel layer thickness control method of nickel-plated high polymer microspheres.

Background

With the advancement of electronic packaging technology, electronic components are continuously moving toward smaller, lighter, high input/output numbers and more environmentally friendly, however, conventional tin-lead soldering has not been able to meet the requirements, and thus new interconnect materials are increasingly urgently needed. Anisotropic Conductive Film (ACF) spontaneous lighting has been developed to date as a connection material for tin-lead solder substitutes. Compared with tin-lead solder, the ACF has the advantages of environmental protection, narrower connectable interval, low working temperature and the like. ACF is composed mainly of a resin binder and conductive particles, wherein the resin binder provides mechanical connection to ACF, and the conductive properties of ACF depend on the conductive particles therein. The current common conductive particles are generally polymer/metal composite microspheres, namely, the polymer microspheres are used as cores, and a metal layer is plated on the surfaces of the polymer microspheres by adopting an electroplating or chemical plating process. Wherein, the macromolecule core layer is usually selected from monodisperse polystyrene microsphere, monodisperse polymethyl methacrylate microsphere, etc., and the shell layer is usually selected from gold, silver, nickel, etc.

Nickel-plated polymer microspheres are favored in ACF applications because of the advantages of good conductivity, high stability, low price, and the like. ACF is often prepared as a conductive filler for connection of electronic calculators, liquid crystals, plasmas, and display panels of various semiconductors to flexible circuit boards. In the nickel plating process, the thickness of the nickel layer and the uniformity thereof are one of important indexes for measuring the quality of the nickel layer. The thickness of the nickel layer directly influences the performances such as corrosion resistance, wear resistance, porosity, conductivity and the like, so that the reliability and the service performance of the product are greatly influenced.

Chinese patent CN 102965702A discloses a method for improving uniformity of thickness of electroplated nickel layer, which solves the problems of thin middle and thick edge of electroplated nickel layer caused by edge effect of electroplating in the process of electroplating nickel. The sand blasting procedure is added before the nickel electroplating, the micron-sized pits with different directions are uniformly distributed on the surface of the alloy matrix, and the nickel electroplating layer can uniformly grow on the surface of the alloy matrix, so that the edge effect of the nickel electroplating is improved. However, the plating requires an external current and an anode, and the thickness is not uniform due to the uneven current distribution, and the binding force of the plating layer is inferior to that of the electroless plating.

Chinese patent CN 103276376A discloses a method for electroless nickel plating on the surface of polymeric microspheres. The polymer microsphere containing functional groups is used as a mother sphere, and the composite redox nickel plating solution is adopted to carry out chemical plating under the combined action of mechanical stirring and ultrasonic waves to obtain the monodisperse conductive microsphere with uniform and firm plating layer and thickness of 1-100 nm. However, the nickel layer of the nickel-plated polymer microsphere with lower thickness is easy to break to cause surface defects, which affect performances such as corrosion resistance, conductivity and the like, and is unfavorable for subsequent application.

The nickel plating layer on the surface of the polymer microsphere is similar to the patent CN 102176337 A,CN 101415863 A,CN 1936078A, but the defects of weak bonding force, poor uniformity, uncontrollable thickness and the like of the plating layer exist. Therefore, it is highly desirable to find an effective preparation method capable of controlling the thickness and uniformity of the nickel layer.

Disclosure of Invention

The invention aims to solve the defects in the prior art, and provides a nickel layer thickness control method of a nickel-plated high polymer microsphere. The preparation method can overcome the defects of poor conductivity, uneven thickness of the electroplated nickel layer, weak binding force and the like caused by uncontrollable thin chemical nickel plating layer in the past, and lays a foundation for preparing ACF with excellent performance.

In order to achieve the above purpose, the present invention adopts the following technical scheme:

the control method of the nickel layer thickness of the nickel plating polymer microsphere comprises the following steps:

step one, coarsening the polymer microspheres:

pouring a coarsening agent into a flask, adding polymer microsphere powder while stirring, after the polymer microsphere is completely soaked in the coarsening agent, stirring for a period of time, performing centrifugal separation on the suspension, washing with water and ethanol in sequence, and drying for later use;

step two, surface treatment of the macromolecule microsphere after coarsening:

dispersing the coarsened polymer microspheres in ultrapure water, adding a pH regulator and an activator, stirring, centrifuging, washing, adding a reducing agent, continuously stirring for a period of time, centrifuging, and washing to obtain activated polymer microspheres;

thirdly, plating nickel on the surface of the activated polymer microsphere by a batch plating method:

dispersing activated polymer microspheres in a buffer solution, heating to a certain temperature, adding nickel plating solution into the activated microsphere dispersion solution in batches under the action of mechanical stirring, adding a certain amount of nickel plating solution in the first batch, adding a certain amount of nickel plating solution after the reaction is completed, repeatedly adding for several times, adjusting the pH value by using a pH regulator during the period, and centrifugally separating to obtain batch nickel plating microspheres;

step four, plating nickel on the surface of the batch nickel plating microsphere by a continuous plating method:

dispersing batch nickel plating microsphere in buffer solution, heating to the same temperature as the step three, adding a certain amount of nickel plating solution into batch nickel plating microsphere dispersion solution for several times, adding each time according to batch plating step, regulating pH value with pH regulator in the whole process, separating, washing, and drying to obtain continuous nickel plating microsphere.

Preferably, in the first step, the coarsening agent is a strong oxidation substance, and the dosage is 10-50mL; the polymer microsphere is one or two of polystyrene and polymethyl methacrylate, and the dosage is 1-20g; the continuous stirring time is 60-150min; the rotational speed of the centrifugal machine is 1000-8000r/min, and the time is 3min.

Preferably, the strong oxidizing substance is one or a mixture of two of concentrated sulfuric acid and potassium dichromate.

Preferably, the dosage of the macromolecule microsphere after coarsening in the second step is 0.1-0.6g; the dosage of the ultrapure water is 10-50mL; the pH regulator is one or more of hydrochloric acid, sodium hydroxide solution, potassium hydroxide solution and ammonia water, and the dosage is 1-10mL; the activator is palladium salt, tin salt or a mixed salt thereof, and the dosage is 0.01-0.1g; the reducing agent is one or more of dimethylamine borate, hydrazine, sodium borohydride, sodium hypophosphite and sodium citrate, and the dosage is 10-100mL; stirring for 10-60min; the rotational speed of the centrifugal machine for separation and purification is 1000-8000r/min, and the time is 3min.

Preferably, the buffer solution with the pH value of 7-10 in the third step comprises one or more of phosphate buffer solution, ethylenediamine tetraacetic acid buffer solution, alkaline phosphatase buffer solution and tris-hydrochloric acid buffer solution, and the dosage is 1-50mL; the heating temperature is 30-70 ℃; the total dosage of the nickel plating solution is 20-100mL, and 10-50mL is added in the first batch; the additional amount is 5-25mL, and the repetition times are 1-3 times; the pH regulator is one or more of hydrochloric acid, sodium hydroxide solution, potassium hydroxide solution and ammonia water, and the pH value is regulated to 6-12; the rotational speed of the centrifugal machine is 1000-8000r/min, and the time is 3min.

Preferably, the buffer solution with the pH value of 7-10 in the fourth step comprises one or more of phosphate buffer solution, ethylenediamine tetraacetic acid buffer solution, alkaline phosphatase buffer solution and tris-hydrochloric acid buffer solution, and the dosage is 1-50mL; the pH regulator is one or more of hydrochloric acid, sodium hydroxide solution, potassium hydroxide solution and ammonia water, and the pH value is regulated to 6-12; the dosage of the nickel plating solution is 60-300mL; the times of adding the nickel plating solution is 1-3 times.

Preferably, the formula of the nickel plating solution in the third and fourth steps is as follows: a main salt, a reducing agent, and a pH adjuster;

the main salt is one or more of nickel acetate tetrahydrate, nickel benzenesulfonate hexahydrate, nickel chloride hexahydrate, nickel hypophosphite hexahydrate and nickel sulfate hexahydrate;

the reducing agent is one or more of dimethylamine borate, hydrazine, sodium borohydride, sodium hypophosphite and sodium citrate;

the pH regulator is one or more of hydrochloric acid, sodium hydroxide solution, potassium hydroxide solution and ammonia water.

Compared with the prior art, the invention has the beneficial effects that:

the invention adopts batch plating and continuous plating methods, and the chemical nickel plating layer with controllable thickness, uniformity, compactness and strong binding force is obtained by controlling the additional times of the nickel plating solution and the separation continuous plating times; the technical means is embodied in the chemical nickel plating stage, and mainly comprises the following two points: firstly, in the chemical nickel plating process, after a first nickel layer is formed, other conditions are kept unchanged, and a proper amount of nickel plating solution is fed in batches. Secondly, after the batch replenishing, separating the nickel plating waste liquid from the microspheres, repeating the first step according to the same conditions, and continuing to plate nickel on the surfaces of the microspheres, thereby further increasing the thickness of the nickel layer. In the technical means, the purpose of controlling the thickness of the nickel layer can be achieved by controlling the supplementing times and the separating and continuing times of the nickel plating solution, and the chemical nickel plating method has the advantages of simple process, safety and environmental protection, and the obtained nickel layer has high reliability and wide application prospect.

Drawings

In order to more particularly and intuitively illustrate an embodiment of the present invention or a technical solution in the prior art, a brief description of the drawings is provided below, which are required to be used in the description of the embodiment or the prior art.

FIG. 1 is a batch nickel-plated microsphere Scanning Electron Microscope (SEM) image;

FIG. 2 is a Scanning Electron Microscope (SEM) image of a further nickel-plated microsphere.

Description of the embodiments

The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments.

Examples

Referring to fig. 1-2, a method for controlling the thickness of a nickel layer of a nickel-plated polymer microsphere, the method comprising the steps of:

step one, coarsening the polymer microspheres:

pouring a coarsening agent into a flask, wherein the coarsening agent increases the microscopic roughness and contact area of the surface to ensure good adhesion of a coating, adding polymer microsphere powder while stirring, after the polymer microsphere is completely soaked in the coarsening agent, stirring for a period of time, centrifugally separating suspension, washing with water and ethanol in sequence, and drying for later use, wherein the coarsening agent is a strong oxidation substance, and the dosage is 10mL; the polymer microsphere is one or two of polystyrene and polymethyl methacrylate, and the dosage is 1g; the continuous stirring time is 60min; the rotating speed of the centrifugal machine is 1000r/min, and the time is 3min;

the strong oxidizing substance is one or two of concentrated sulfuric acid and potassium dichromate.

Step two, surface treatment of the macromolecule microsphere after coarsening:

dispersing the macromolecule microspheres in ultrapure water after coarsening, adding a pH regulator and an activator, adsorbing active particles by the activator to form active sites, enabling the reaction to be more complete, stirring, centrifuging and washing, adding a reducing agent, continuously stirring for a period of time, centrifuging and washing to obtain activated macromolecule microspheres, wherein the dosage of the macromolecule microspheres for coarsening is 0.1g; the dosage of the ultrapure water is 10mL; the pH regulator is one or more of hydrochloric acid, sodium hydroxide solution, potassium hydroxide solution and ammonia water, and the dosage is 1mL; the activator is palladium salt, tin salt or a mixed salt thereof, and the dosage is 0.01g; the reducing agent is one or more of dimethylamine borate, hydrazine, sodium borohydride, sodium hypophosphite and sodium citrate, and the dosage is 10mL; stirring for 10min; the rotational speed of the centrifugal machine for separation and purification is 1000r/min, and the time is 3min

Thirdly, plating nickel on the surface of the activated polymer microsphere by a batch plating method:

dispersing activated polymer microspheres in a buffer solution, heating to a certain temperature, adding nickel plating solution into the activated microsphere dispersion solution in batches under the action of mechanical stirring, adding a certain amount of nickel plating solution in the first batch, adding a certain amount of nickel plating solution after the reaction is completed, repeatedly adding for several times, adjusting the pH value by using a pH regulator during the period, and centrifugally separating to obtain batch nickel plating microspheres;

buffer solution with pH of 7, wherein the buffer solution keeps the pH of the system stable, and comprises one or more of phosphate buffer solution, ethylenediamine tetraacetic acid buffer solution, alkaline phosphatase buffer solution and tris-hydrochloric acid buffer solution, and the dosage is 1mL; the heating temperature is 30 ℃; the total dosage of the nickel plating solution is 20mL, and 10mL is added in the first batch; the addition amount is 5mL, and the repetition times are 1 time; the pH regulator is one or more of hydrochloric acid, sodium hydroxide solution, potassium hydroxide solution and ammonia water, and the pH value is regulated to 6; the rotational speed of the centrifugal machine is 1000-8000r/min, and the time is 3min.

Step four, plating nickel on the surface of the batch nickel plating microsphere by a continuous plating method:

dispersing batch nickel plating microspheres in buffer solution, heating to the same temperature as the three phases of the step, adding a certain amount of nickel plating solution into the batch nickel plating microsphere dispersion solution for several times, adding each time according to the batch plating step, adjusting the pH value by adopting a pH regulator in the whole process, and separating, washing and drying to obtain continuous nickel plating microspheres;

buffer solution with pH of 7, including one or more of phosphate buffer solution, ethylenediamine tetraacetic acid buffer solution, alkaline phosphatase buffer solution, and tris-hydrochloric acid buffer solution, with dosage of 1mL; the pH regulator is one or more of hydrochloric acid, sodium hydroxide solution, potassium hydroxide solution and ammonia water, and the pH value is regulated to 6; the dosage of the nickel plating solution is 60mL; the number of times of adding the nickel plating solution is 1.

Examples

Referring to fig. 1-2, a method for controlling the thickness of a nickel layer of a nickel-plated polymer microsphere, the method comprising the steps of:

step one, coarsening the polymer microspheres:

pouring a coarsening agent into a flask, wherein the coarsening agent increases the microscopic roughness and contact area of the surface to ensure good adhesion of a coating, adding polymer microsphere powder while stirring, after the polymer microsphere is completely soaked in the coarsening agent, stirring for a period of time, centrifugally separating suspension, washing with water and ethanol in sequence, and drying for later use, wherein the coarsening agent is a strong oxidation substance, and the dosage is 30mL; the polymer microsphere is one or two of polystyrene and polymethyl methacrylate, and the dosage is 10.5g; the continuous stirring time is 105min; the rotation speed of the centrifugal machine is 4500r/min, and the time is 3min;

the strong oxidizing substance is one or two of concentrated sulfuric acid and potassium dichromate.

Step two, surface treatment of the macromolecule microsphere after coarsening:

dispersing the macromolecule microspheres in ultrapure water after coarsening, adding a pH regulator and an activator, adsorbing active particles by the activator to form active sites, enabling the reaction to be more complete, stirring, centrifuging and washing, adding a reducing agent, continuously stirring for a period of time, centrifuging and washing to obtain activated macromolecule microspheres, wherein the dosage of the macromolecule microspheres for coarsening is 0.35g; the dosage of the ultrapure water is 30mL; the pH regulator is one or more of hydrochloric acid, sodium hydroxide solution, potassium hydroxide solution and ammonia water, and the dosage is 5.5mL; the activator is palladium salt, tin salt or a mixed salt thereof, and the dosage is 0.525g; the reducing agent is one or more of dimethylamine borate, hydrazine, sodium borohydride, sodium hypophosphite and sodium citrate, and the dosage is 55mL; stirring for 35min; the rotation speed of the centrifugal machine for separation and purification is 4500r/min, and the time is 3min

Thirdly, plating nickel on the surface of the activated polymer microsphere by a batch plating method:

dispersing activated polymer microspheres in a buffer solution, heating to a certain temperature, adding nickel plating solution into the activated microsphere dispersion solution in batches under the action of mechanical stirring, adding a certain amount of nickel plating solution in the first batch, adding a certain amount of nickel plating solution after the reaction is completed, repeatedly adding for several times, adjusting the pH value by using a pH regulator during the period, and centrifugally separating to obtain batch nickel plating microspheres;

buffer solution with pH of 8.5, wherein the buffer solution keeps the pH of the system stable, and comprises one or more of phosphate buffer solution, ethylenediamine tetraacetic acid buffer solution, alkaline phosphatase buffer solution and tris-hydrochloric acid buffer solution, and the dosage is 25.5mL; the heating temperature is 50 ℃; the total dosage of the nickel plating solution is 60mL, and 30mL is added in the first batch; the addition amount is 15mL, and the repetition times are 2 times; the pH regulator is one or more of hydrochloric acid, sodium hydroxide solution, potassium hydroxide solution and ammonia water, and the pH value is regulated to 9; the rotational speed of the centrifuge is 4500r/min, and the time is 3min.

Step four, plating nickel on the surface of the batch nickel plating microsphere by a continuous plating method:

dispersing batch nickel plating microspheres in buffer solution, heating to the same temperature as the three phases of the step, adding a certain amount of nickel plating solution into the batch nickel plating microsphere dispersion solution for several times, adding each time according to the batch plating step, adjusting the pH value by adopting a pH regulator in the whole process, and separating, washing and drying to obtain continuous nickel plating microspheres;

buffer solution with pH of 8.5, including one or more of phosphate buffer solution, ethylenediamine tetraacetic acid buffer solution, alkaline phosphatase buffer solution, and tris-hydrochloric acid buffer solution, with dosage of 25.5mL; the pH regulator is one or more of hydrochloric acid, sodium hydroxide solution, potassium hydroxide solution and ammonia water, and the pH value is regulated to 9; the dosage of the nickel plating solution is 180mL; the number of times of adding the nickel plating solution is 2.

Examples

Referring to fig. 1-2, a method for controlling the thickness of a nickel layer of a nickel-plated polymer microsphere, the method comprising the steps of:

step one, coarsening the polymer microspheres:

pouring a coarsening agent into a flask, wherein the coarsening agent increases the microscopic roughness and contact area of the surface to ensure good adhesion of a coating, adding polymer microsphere powder while stirring, after the polymer microsphere is completely soaked in the coarsening agent, stirring for a period of time, centrifugally separating suspension, washing with water and ethanol in sequence, and drying for later use, wherein the coarsening agent is a strong oxidation substance, and the dosage is 50mL; the polymer microsphere is one or two of polystyrene and polymethyl methacrylate, and the dosage is 20g; the continuous stirring time is 150min; the rotating speed of the centrifugal machine is 8000r/min, and the time is 3min;

the strong oxidizing substance is one or two of concentrated sulfuric acid and potassium dichromate.

Step two, surface treatment of the macromolecule microsphere after coarsening:

dispersing the macromolecule microspheres in ultrapure water after coarsening, adding a pH regulator and an activator, adsorbing active particles by the activator to form active sites, enabling the reaction to be more complete, stirring, centrifuging and washing, adding a reducing agent, continuously stirring for a period of time, centrifuging and washing to obtain activated macromolecule microspheres, wherein the dosage of the macromolecule microspheres for coarsening is 0.6g; the dosage of the ultrapure water is 50mL; the pH regulator is one or more of hydrochloric acid, sodium hydroxide solution, potassium hydroxide solution and ammonia water, and the dosage is 10mL; the activator is palladium salt, tin salt or a mixed salt thereof, and the dosage is 0.1g; the reducing agent is one or more of dimethylamine borate, hydrazine, sodium borohydride, sodium hypophosphite and sodium citrate, and the dosage is 100mL; stirring for 60min; the rotational speed of the centrifugal machine for separation and purification is 8000r/min, and the time is 3min

Thirdly, plating nickel on the surface of the activated polymer microsphere by a batch plating method:

dispersing activated polymer microspheres in a buffer solution, heating to a certain temperature, adding nickel plating solution into the activated microsphere dispersion solution in batches under the action of mechanical stirring, adding a certain amount of nickel plating solution in the first batch, adding a certain amount of nickel plating solution after the reaction is completed, repeatedly adding for several times, adjusting the pH value by using a pH regulator during the period, and centrifugally separating to obtain batch nickel plating microspheres;

buffer solution with pH of 10, wherein the buffer solution keeps the pH of the system stable, and comprises one or more of phosphate buffer solution, ethylenediamine tetraacetic acid buffer solution, alkaline phosphatase buffer solution and tris-hydrochloric acid buffer solution, and the dosage is 50mL; the heating temperature is 70 ℃; the total dosage of the nickel plating solution is 100mL, and 50mL is added in the first batch; the additional amount is 25mL, and the repetition times are 3 times; the pH regulator is one or more of hydrochloric acid, sodium hydroxide solution, potassium hydroxide solution and ammonia water, and the pH value is regulated to 12; the rotational speed of the centrifugal machine is 8000r/min, and the time is 3min.

Step four, plating nickel on the surface of the batch nickel plating microsphere by a continuous plating method:

dispersing batch nickel plating microspheres in buffer solution, heating to the same temperature as the three phases of the step, adding a certain amount of nickel plating solution into the batch nickel plating microsphere dispersion solution for several times, adding each time according to the batch plating step, adjusting the pH value by adopting a pH regulator in the whole process, and separating, washing and drying to obtain continuous nickel plating microspheres;

buffer solution with pH of 10, including one or more of phosphate buffer solution, ethylenediamine tetraacetic acid buffer solution, alkaline phosphatase buffer solution, and tris-hydrochloric acid buffer solution, with dosage of 50mL; the pH regulator is one or more of hydrochloric acid, sodium hydroxide solution, potassium hydroxide solution and ammonia water, and the pH value is regulated to 12; the dosage of the nickel plating solution is 300mL; the number of times of adding the nickel plating solution is 3.

In this embodiment, the formula of the nickel plating solution in the third and fourth steps is as follows: a main salt, a reducing agent, and a pH adjuster; the main salt is one or more of nickel acetate tetrahydrate, nickel benzenesulfonate hexahydrate, nickel chloride hexahydrate, nickel hypophosphite hexahydrate and nickel sulfate hexahydrate; the reducing agent is one or more of dimethylamine borate, hydrazine, sodium borohydride, sodium hypophosphite and sodium citrate; the pH regulator is one or more of hydrochloric acid, sodium hydroxide solution, potassium hydroxide solution and ammonia water.

In the chemical nickel plating process, the thickness of the nickel layer is controlled by controlling the times of batch plating and continuous plating, so that a metal nickel layer with the thickness of tens to hundreds of nanometers and uniform and compact distribution is obtained.

The technical means is embodied in the chemical nickel plating stage, and mainly comprises the following two points: firstly, in the chemical nickel plating process, after a first nickel layer is formed, other conditions are kept unchanged, and a proper amount of nickel plating solution is fed in batches. Secondly, after the nickel plating waste liquid is supplemented in batches, the nickel plating waste liquid and the microspheres are separated, the first step is repeated according to the same condition, and the nickel plating is continuously carried out on the surfaces of the microspheres, so that the thickness of the nickel layer is further increased.

The foregoing is only a preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art, who is within the scope of the present invention, should make equivalent substitutions or modifications according to the technical scheme of the present invention and the inventive concept thereof, and should be covered by the scope of the present invention.

Claims (7)

1. The method for controlling the thickness of the nickel layer of the nickel-plated high polymer microsphere is characterized by comprising the following steps:

step one, coarsening the polymer microspheres:

pouring a coarsening agent into a flask, adding polymer microsphere powder while stirring, after the polymer microsphere is completely soaked in the coarsening agent, stirring for a period of time, performing centrifugal separation on the suspension, washing with water and ethanol in sequence, and drying for later use;

step two, surface treatment of the macromolecule microsphere after coarsening:

dispersing the coarsened polymer microspheres in ultrapure water, adding a pH regulator and an activator, stirring, centrifuging, washing, adding a reducing agent, continuously stirring for a period of time, centrifuging, and washing to obtain activated polymer microspheres;

thirdly, plating nickel on the surface of the activated polymer microsphere by a batch plating method:

dispersing activated polymer microspheres in a buffer solution, heating to a certain temperature, adding nickel plating solution into the activated microsphere dispersion solution in batches under the action of mechanical stirring, adding a certain amount of nickel plating solution in the first batch, adding a certain amount of nickel plating solution after the reaction is completed, repeatedly adding for several times, adjusting the pH value by using a pH regulator during the period, and centrifugally separating to obtain batch nickel plating microspheres;

step four, plating nickel on the surface of the batch nickel plating microsphere by a continuous plating method:

dispersing batch nickel plating microsphere in buffer solution, heating to the same temperature as the step three, adding a certain amount of nickel plating solution into batch nickel plating microsphere dispersion solution for several times, adding each time according to batch plating step, regulating pH value with pH regulator in the whole process, separating, washing, and drying to obtain continuous nickel plating microsphere.

2. The method for controlling the thickness of a nickel layer of a nickel-plated polymer microsphere according to claim 1, wherein in the first step, the coarsening agent is a strong oxidation substance, and the dosage is 10-50mL; the polymer microsphere is one or two of polystyrene and polymethyl methacrylate, and the dosage is 1-20g; the continuous stirring time is 60-150min; the rotational speed of the centrifugal machine is 1000-8000r/min, and the time is 3min.

3. The method for controlling the thickness of a nickel layer of a nickel-plated polymer microsphere according to claim 2, wherein the strong oxidizing substance is one or a mixture of two of concentrated sulfuric acid and potassium dichromate.

4. The method for controlling the thickness of a nickel layer of a nickel-plated polymer microsphere according to claim 3, wherein the dosage of the polymer microsphere after coarsening in the second step is 0.1-0.6g; the dosage of the ultrapure water is 10-50mL; the pH regulator is one or more of hydrochloric acid, sodium hydroxide solution, potassium hydroxide solution and ammonia water, and the dosage is 1-10mL; the activator is palladium salt, tin salt or a mixed salt thereof, and the dosage is 0.01-0.1g; the reducing agent is one or more of dimethylamine borate, hydrazine, sodium borohydride, sodium hypophosphite and sodium citrate, and the dosage is 10-100mL; stirring for 10-60min; the rotational speed of the centrifugal machine for separation and purification is 1000-8000r/min, and the time is 3min.

5. The method for controlling the thickness of a nickel layer of a nickel-plated polymer microsphere according to claim 4, wherein the buffer solution with the pH of 7-10 in the third step comprises one or more of phosphate buffer solution, ethylenediamine tetraacetic acid buffer solution, alkaline phosphatase buffer solution and tris-hydroxymethyl aminomethane-hydrochloric acid buffer solution, and the dosage is 1-50mL; the heating temperature is 30-70 ℃; the total dosage of the nickel plating solution is 20-100mL, and 10-50mL is added in the first batch; the additional amount is 5-25mL, and the repetition times are 1-3 times; the pH regulator is one or more of hydrochloric acid, sodium hydroxide solution, potassium hydroxide solution and ammonia water, and the pH value is regulated to 6-12; the rotational speed of the centrifugal machine is 1000-8000r/min, and the time is 3min.

6. The method for controlling the nickel layer thickness of the nickel-plated polymer microsphere according to claim 5, wherein the buffer solution with the pH of 7-10 in the fourth step comprises one or more of phosphate buffer solution, ethylenediamine tetraacetic acid buffer solution, alkaline phosphatase buffer solution and tris-hydroxymethyl aminomethane-hydrochloric acid buffer solution, and the dosage is 1-50mL; the pH regulator is one or more of hydrochloric acid, sodium hydroxide solution, potassium hydroxide solution and ammonia water, and the pH value is regulated to 6-12; the dosage of the nickel plating solution is 60-300mL; the times of adding the nickel plating solution is 1-3 times.

7. The method for controlling the thickness of a nickel layer of a nickel-plated polymer microsphere according to claim 6, wherein the nickel plating solution in the third and fourth steps comprises the following formula: a main salt, a reducing agent, and a pH adjuster;

the main salt is one or more of nickel acetate tetrahydrate, nickel benzenesulfonate hexahydrate, nickel chloride hexahydrate, nickel hypophosphite hexahydrate and nickel sulfate hexahydrate;

the reducing agent is one or more of dimethylamine borate, hydrazine, sodium borohydride, sodium hypophosphite and sodium citrate;

the pH regulator is one or more of hydrochloric acid, sodium hydroxide solution, potassium hydroxide solution and ammonia water.