CN114457325A - Method for controlling thickness of nickel layer of nickel-plated polymer microsphere - Google Patents

Abstract

The invention discloses a nickel layer thickness control method of nickel-plated polymer microspheres, which comprises the following steps: coarsening the polymer microsphere, treating the surface of the polymer microsphere after coarsening, 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 method of batch plating and continuous plating is adopted, and the chemical nickel plating layer with controllable thickness, uniformity, compactness and strong binding force is obtained by controlling the replenishing frequency of the nickel plating solution and separating the continuous plating frequency.

Description

Method for controlling thickness of nickel layer of nickel-plated polymer microsphere

Technical Field

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

Background

With the advancement of electronic packaging technology, electronic components are continuously being developed toward smaller, lighter, higher input/output number and more environmental protection, however, traditional tin-lead soldering has not been able to meet the requirements, and thus there is an increasing urgent need for new interconnection materials. Anisotropic Conductive Films (ACFs) have been developed to date as a connecting material as a substitute for tin-lead solder. Compared with tin-lead solder, the ACF has the advantages of environmental protection, narrower connectable distance, low working temperature and the like. The ACF is mainly composed of a resin binder and conductive particles, wherein the resin binder provides mechanical connection to the ACF, and the conductive properties of the ACF depend on the conductive particles therein. At present, the commonly used conductive particles are generally polymer/metal composite microspheres, that is, 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 polymer core layer is usually selected from monodisperse polystyrene microspheres, monodisperse polymethyl methacrylate microspheres and the like, and the shell layer is usually selected from metals such as gold, silver, nickel and the like.

The nickel-plated polymer microspheres are favored in ACF application due to the advantages of good conductivity, high stability, low price and the like. ACFs are often prepared as conductive fillers for the attachment of display panels to flexible circuit boards for electronic calculators, liquid crystals, plasma, and various semiconductors. 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 influenced to a great extent.

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

Chinese patent CN 103276376a discloses a method for chemically plating nickel on the surface of polymer microsphere. The polymer microsphere containing functional groups is used as a mother sphere, and under the combined action of mechanical stirring and ultrasonic waves, the composite redox nickel plating solution is adopted for chemical plating to obtain the monodisperse conductive microsphere with uniform and firm plating layer and the thickness of 1-100 nm. However, the nickel layer of the nickel-plated polymer microsphere with a low nickel layer thickness is easy to crack to cause surface defects, influence the performances such as corrosion resistance, conductivity and the like, and is not beneficial to subsequent application.

The nickel plating layer on the surface of the polymer microsphere is similar to patents CN 102176337A, CN 101415863A and CN 1936078A, but the defects of weak plating bonding force, poor uniformity, uncontrollable thickness and the like exist. Therefore, it is urgently needed 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 method for controlling the thickness of a nickel layer of a nickel-plated 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 thickness of the traditional chemical nickel plating layer, and lays a foundation for preparing the ACF with excellent performance.

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

a nickel layer thickness control method of nickel-plated polymer microspheres comprises the following steps:

step one, coarsening polymer microspheres:

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

step two, roughening the surface of the polymer microsphere:

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

step three, 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 a nickel plating solution into the activated polymer microsphere dispersion solution in batches under the action of mechanical stirring, adding a certain amount of nickel plating solution in the first batch, supplementing a certain amount of nickel plating solution after the reaction is finished, repeating the supplementing for several times, adjusting the pH value by using a pH regulator during the process, and performing centrifugal separation to obtain batch nickel plating microspheres;

step four, plating nickel on the surfaces of the batch nickel-plated microspheres by a continuous plating method:

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

Preferably, the coarsening agent in the step one is a strong oxidation substance, and the dosage is 10-50 mL; the polymer microsphere is one or a mixture of polystyrene and polymethyl methacrylate, and the dosage is 1-20 g; continuously stirring for 60-150 min; the rotating speed of the centrifuge is 1000-.

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

Preferably, the dosage of the coarsening polymer microspheres in the second step is 0.1-0.6 g; the dosage of the ultrapure water is 10-50 mL; the pH regulator is one or a mixture of hydrochloric acid, a sodium hydroxide solution, a potassium hydroxide solution and ammonia water, and the dosage is 1-10 mL; the activator is palladium salt, tin salt or mixed salt thereof, and the dosage is 0.01-0.1 g; the reducing agent is one or a mixture of more of dimethylamine borate, hydrazine, sodium borohydride, sodium hypophosphite and sodium citrate, and the dosage is 10-100 mL; stirring for 10-60 min; the rotating speed of the centrifuge for separation and purification is 1000-.

Preferably, the buffer solution with the pH value of 7-10 in the third step comprises one or more of phosphate buffer solution, ethylene diamine tetraacetic acid buffer solution, alkaline phosphatase buffer solution and tris (hydroxymethyl) aminomethane-hydrochloric acid buffer solution, and the dosage is 1-50 mL; 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 addition amount is 5-25mL, and the repetition times are 1-3 times; the pH regulator is one or a mixture of hydrochloric acid, sodium hydroxide solution, potassium hydroxide solution and ammonia water, and the pH value is regulated to 6-12; the rotating speed of the centrifuge is 1000-.

Preferably, the buffer solution with the pH value of 7-10 in the fourth step comprises one or more of phosphate buffer solution, ethylene diamine tetraacetic acid buffer solution, alkaline phosphatase buffer solution and tris-hydrochloric acid buffer solution, and the dosage is 1-50 mL; the pH regulator is one or a mixture 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 60-300 mL; the nickel plating solution is added for 1 to 3 times.

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

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

the reducing agent is one or a mixture of 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 a method of batch plating and continuous plating, and obtains a chemical nickel plating layer with controllable thickness, uniformity, compactness and strong bonding force by controlling the replenishing times of the nickel plating solution and the separating continuous plating times; the technical means is embodied in the chemical nickel plating stage and mainly comprises the following two steps: 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 added in batches. Secondly, after the nickel plating waste liquid is supplemented in batches, the nickel plating waste liquid is separated from the microspheres, the first step is repeated according to the same conditions, and the nickel plating is continuously carried out on the surfaces of the microspheres, so that the thickness of a nickel layer is further increased. In the technical means, the purpose of controlling the thickness of the nickel layer can be achieved by controlling the replenishing times of the nickel plating solution and the continuous plating times of separation.

Drawings

In order to more particularly and intuitively illustrate an embodiment of the present invention or a prior art solution, a brief description of the drawings needed for use in the description of the embodiment or the prior art will be provided below.

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

FIG. 2 is a Scanning Electron Microscope (SEM) image of the microspheres continuously plated with nickel.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments.

Example one

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

step one, coarsening polymer microspheres:

pouring a coarsening agent into a flask, wherein the coarsening agent increases the surface micro roughness and the contact area to ensure that a plating layer has good adhesive force, adding polymer microsphere powder while stirring, after the polymer microspheres are completely soaked in the coarsening agent, stirring for a period of time, carrying out centrifugal separation on 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 10 mL; the polymer microsphere is one or a mixture of polystyrene and polymethyl methacrylate, and the using amount is 1 g; continuously stirring for 60 min; the rotating speed of the centrifuge is 1000r/min, and the time is 3 min;

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

Step two, roughening the surface of the polymer microsphere:

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

Step three, 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 a nickel plating solution into the activated polymer microsphere dispersion solution in batches under the action of mechanical stirring, adding a certain amount of nickel plating solution in the first batch, supplementing a certain amount of nickel plating solution after the reaction is finished, repeating the supplementing for several times, adjusting the pH value by using a pH regulator during the process, and performing centrifugal separation to obtain batch nickel plating microspheres;

the buffer solution has a pH value of 7, the buffer solution keeps the pH value of the system stable and comprises one or more of phosphate buffer solution, ethylene diamine tetraacetic acid buffer solution, alkaline phosphatase buffer solution and tris-hydroxymethyl aminomethane-hydrochloric acid buffer solution, and the dosage is 1 mL; 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 frequency is 1 time; the pH regulator is one or a mixture of hydrochloric acid, sodium hydroxide solution, potassium hydroxide solution and ammonia water, and the pH value is regulated to 6; the rotating speed of the centrifuge is 1000-.

Step four, plating nickel on the surfaces of the batch nickel-plated microspheres by a continuous plating method:

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

the buffer solution with the pH value of 7 comprises one or more of phosphate buffer solution, ethylene diamine tetraacetic acid buffer solution, alkaline phosphatase buffer solution and tris-hydrochloric acid buffer solution, and the dosage is 1 mL; the pH regulator is one or a mixture 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 60 mL; the number of times of adding the nickel plating solution was 1.

Example two

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

step one, coarsening polymer microspheres:

pouring a coarsening agent into a flask, wherein the coarsening agent increases the surface micro roughness and the contact area to ensure that a plating layer has good adhesive force, adding polymer microsphere powder while stirring, after the polymer microspheres are completely soaked in the coarsening agent, stirring for a period of time, carrying out centrifugal separation on suspension, washing with water and ethanol in sequence, and drying for later use, wherein the coarsening agent is a strong oxidation substance and is used in an amount of 30 mL; the polymer microsphere is one or a mixture of polystyrene and polymethyl methacrylate, and the using amount is 10.5 g; continuously stirring for 105 min; the rotating speed of the centrifuge is 4500r/min, and the time is 3 min;

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

Step two, surface treatment of the coarsened polymer microspheres:

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

Step three, 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 a nickel plating solution into the activated polymer microsphere dispersion solution in batches under the action of mechanical stirring, adding a certain amount of nickel plating solution in the first batch, supplementing a certain amount of nickel plating solution after the reaction is finished, repeating the supplementing for several times, adjusting the pH value by using a pH regulator during the process, and performing centrifugal separation to obtain batch nickel plating microspheres;

the buffer solution has the pH value of 8.5, the buffer solution keeps the pH value of the system stable and comprises one or more of phosphate buffer solution, ethylene diamine tetraacetic acid buffer solution, alkaline phosphatase buffer solution and tris (hydroxymethyl) aminomethane-hydrochloric acid buffer solution, and the dosage is 25.5 mL; 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 is 2 times; the pH regulator is one or a mixture of hydrochloric acid, sodium hydroxide solution, potassium hydroxide solution and ammonia water, and the pH value is regulated to 9; the rotating speed of the centrifuge is 4500r/min, and the time is 3 min.

Step four, plating nickel on the surfaces of the batch nickel-plated microspheres by a continuous plating method:

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

the buffer solution with the pH value of 8.5 comprises one or more of phosphate buffer solution, ethylene diamine tetraacetic acid buffer solution, alkaline phosphatase buffer solution and tris-hydroxymethyl aminomethane-hydrochloric acid buffer solution, and the dosage is 25.5 mL; the pH regulator is one or a mixture 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 180 mL; the number of times of adding the nickel plating solution was 2.

EXAMPLE III

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

step one, coarsening polymer microspheres:

pouring a coarsening agent into a flask, wherein the coarsening agent increases the surface micro roughness and the contact area to ensure that a plating layer has good adhesive force, adding polymer microsphere powder while stirring, after the polymer microspheres are completely soaked in the coarsening agent, stirring for a period of time, carrying out centrifugal separation on 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 50 mL; the polymer microsphere is one or a mixture of polystyrene and polymethyl methacrylate, and the using amount is 20 g; the continuous stirring time is 150 min; the rotating speed of the centrifuge is 8000r/min, and the time is 3 min;

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

Step two, roughening the surface of the polymer microsphere:

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

Step three, 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 a nickel plating solution into the activated polymer microsphere dispersion solution in batches under the action of mechanical stirring, adding a certain amount of nickel plating solution in the first batch, supplementing a certain amount of nickel plating solution after the reaction is finished, repeating the supplementing for several times, adjusting the pH value by using a pH regulator during the process, and performing centrifugal separation to obtain batch nickel plating microspheres;

the buffer solution has a pH value of 10, the buffer solution keeps the pH value of the system stable and comprises one or more of phosphate buffer solution, ethylene diamine tetraacetic acid buffer solution, alkaline phosphatase buffer solution and tris-hydroxymethyl aminomethane-hydrochloric acid buffer solution, and the dosage is 50 mL; the heating temperature is 70 ℃; the total dosage of the nickel plating solution is 100mL, and 50mL is added in the first batch; the addition amount is 25mL, and the repetition times is 3 times; the pH regulator is one or a mixture of hydrochloric acid, sodium hydroxide solution, potassium hydroxide solution and ammonia water, and the pH value is regulated to 12; the rotation speed of the centrifuge is 8000r/min, and the time is 3 min.

Step four, plating nickel on the surfaces of the batch nickel-plated microspheres by a continuous plating method:

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

the buffer solution with the pH value of 10 comprises one or more of phosphate buffer solution, ethylene diamine tetraacetic acid buffer solution, alkaline phosphatase buffer solution and tris (hydroxymethyl) aminomethane-hydrochloric acid buffer solution, and the dosage is 50 mL; the pH regulator is one or a mixture 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 300 mL; the number of times of adding the nickel plating solution was 3.

In the embodiment, the formula of the nickel plating solution in the third step and the fourth step is as follows: main salt, reducing agent and pH regulator; the main salt is one or a mixture of nickel acetate tetrahydrate, nickel benzenesulfonate hexahydrate, nickel chloride hexahydrate, nickel hypophosphite hexahydrate and nickel sulfate hexahydrate; the reducing agent is one or a mixture of 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 scheme, in the chemical nickel plating process, the thickness of the nickel layer is controlled by controlling the times of batch plating and continuous plating, and the metal nickel layer with the thickness of dozens of 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 steps: 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 added in batches. Secondly, after the batch nickel plating is supplemented, the nickel plating waste liquid is separated from the microspheres, the first step is repeated according to the same conditions, and the nickel plating is continuously carried out on the surfaces of the microspheres, so that the thickness of a nickel layer is further increased.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.

Claims (7)

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

step one, coarsening polymer microspheres:

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

step two, roughening the surface of the polymer microsphere:

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

step three, 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 a nickel plating solution into the activated polymer microsphere dispersion solution in batches under the action of mechanical stirring, adding a certain amount of nickel plating solution in the first batch, supplementing a certain amount of nickel plating solution after the reaction is finished, repeating the supplementing for several times, adjusting the pH value by using a pH regulator during the process, and performing centrifugal separation to obtain batch nickel plating microspheres;

step four, plating nickel on the surfaces of the batch nickel-plated microspheres by a continuous plating method:

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

2. The method for controlling the thickness of the nickel layer of the 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 10-50 mL; the polymer microsphere is one or a mixture of polystyrene and polymethyl methacrylate, and the dosage is 1-20 g; continuously stirring for 60-150 min; the rotating speed of the centrifuge is 1000-.

3. The method of claim 2, wherein the strongly oxidizing substance is one or a mixture of concentrated sulfuric acid and potassium dichromate.

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

5. The method for controlling the thickness of the nickel layer of the nickel-plated polymer microspheres 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, ethylene diamine tetraacetic acid buffer solution, alkaline phosphatase buffer solution and tris-hydrochloric acid buffer solution, and the amount of the buffer solution is 1-50 mL; 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 addition amount is 5-25mL, and the repetition times are 1-3 times; the pH regulator is one or a mixture of hydrochloric acid, sodium hydroxide solution, potassium hydroxide solution and ammonia water, and the pH value is regulated to 6-12; the rotating speed of the centrifuge is 1000-.

6. The method for controlling the thickness of the nickel layer of the nickel-plated polymer microspheres 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, ethylene diamine tetraacetic acid buffer solution, alkaline phosphatase buffer solution and tris-hydrochloric acid buffer solution, and the dosage is 1-50 mL; the pH regulator is one or a mixture 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 60-300 mL; the nickel plating solution is added for 1 to 3 times.

7. The method for controlling the thickness of the nickel layer of the nickel-plated polymer microsphere according to claim 6, wherein the formula of the nickel plating solution in the third step and the fourth step is as follows: main salt, reducing agent and pH regulator;

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

the reducing agent is one or a mixture of 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.

Images