CN109576684B

CN109576684B - Method for chemical plating of polymer film surface

Info

Publication number: CN109576684B
Application number: CN201910088158.1A
Authority: CN
Inventors: 熊立双; 刘阳; 杭弢; 吴蕴雯; 高立明; 李明
Original assignee: Shanghai Jiaotong University
Current assignee: Shanghai Jiaotong University
Priority date: 2019-01-29
Filing date: 2019-01-29
Publication date: 2020-12-08
Anticipated expiration: 2039-01-29
Also published as: CN109576684A

Abstract

The invention discloses a method for chemical plating of a polymer film surface, which comprises the following steps: a1: placing a polymer film in a functional solution, and standing and grafting for 10-120 min at the temperature of 20-25 ℃ to graft a pyridine group on the surface of the polymer film; a2: placing the sample obtained in the step A1 in an activation solution, and continuously stirring for 5-30 min at the temperature of 20-25 ℃; a3: and B, placing the sample obtained in the step A2 in chemical plating solution, adjusting the temperature to a preset temperature, and continuously stirring for 15-45 min. The invention grafts the pyridine group on the surface of the polymer, the pyridine group can provide a chemical adsorption site for active ions, and the pyridine group has stronger adsorption effect on the active ions or atoms, thereby leading the polymer film to have a surface with catalytic activity after being activated and further leading the surface of the polymer film to be smoothly plated with a metal layer.

Description

Method for chemical plating of polymer film surface

Technical Field

The invention belongs to the technical field of chemical plating, and particularly relates to a method for chemical plating of a polymer film surface.

Background

Polymer films have been increasingly used in microelectronic packaging, automotive industry, and optoelectronic devices in recent years due to their good thermal stability, insulation, and optoelectronic properties. The metallization of polymer films has thus attracted a great deal of attention. However, metallization of polymer films is a problem due to their low surface energy and poor inherent adhesion. Common methods for metallizing polymer films include magnetron sputtering, physical vapor deposition, and chemical vapor deposition. However, these methods are environmentally demanding, often require vacuum conditions, and are expensive and complicated to operate, limiting their utility. Electroless plating effectively solves this problem. Electroless plating is an autocatalytic reaction in which metal ions are reduced on the active surface to obtain a metal coating. The chemical plating can be suitable for most polymers, and the plating layer is uniform and controllable in thickness. Moreover, the chemical plating can be carried out in the atmospheric environment, the operation is simple, the cost is low, and the method is a good polymer surface metallization method.

However, polymers, especially polymer films with low surface roughness, generally have low surface energy and thus have no catalytic activity on the surface, and are difficult to deposit electrolessly, and therefore, the surface needs to be pretreated before electroless plating. Common pretreatment methods are surface roughening and surface plasma treatment. However, hexavalent chromium ions are generally used for surface roughening, which causes serious environmental pollution, and the plasma treatment of the surface may cause some damage to the surface.

Disclosure of Invention

The technical problem to be solved by the invention is to provide a method for chemical plating on the surface of a polymer film, and particularly, the method provides a method for pretreating the surface of the polymer film, so that the surface of the polymer film is grafted with pyridine groups, the surface of the polymer film has catalytic activity after being activated, and subsequent chemical plating is smoothly performed.

In order to solve the problems, the technical scheme of the invention is as follows:

a method of chemical plating a surface of a polymer film, comprising:

a1: surface functionalization of polymer film: placing a polymer film in a functional solution, and standing and grafting for 10-120 min at the temperature of 20-25 ℃ to graft a pyridine group on the surface of the polymer film;

a2: polymer surface activation: placing the sample obtained in the step A1 in an activation solution, and continuously stirring for 5-30 min at the temperature of 20-25 ℃ to obtain a polymer film adsorbed with activated ions or atoms;

a3: chemical plating: and B, placing the sample obtained in the step A2 in chemical plating solution, adjusting the temperature to a preset temperature, continuously stirring for 15-45 min, and performing chemical plating operation.

Specifically, the step a1 specifically includes:

cleaning and drying the polymer film;

and (3) placing the polymer film into the prepared functional solution, standing and grafting for 10min at the temperature of 20-25 ℃, washing with deionized water, and drying.

Preferably, the chemical composition of the functionalization solution is selected from one of the following:

2vt percent of fluoboric acid, 1vt percent of hydrofluoric acid, 0.005-0.02 moL/L of 4-nitrotetrafluoroboric acid benzene poly-ether, 0.005-0.04 moL/L of surfactant and 1-4 vt percent of 4-vinylpyridine; or

2vt percent of concentrated hydrochloric acid, 1vt percent of hydrofluoric acid, 0.005-0.02 moL/L of 4-nitrotetrafluoroboric acid benzene poly-p-phenylene, 0.005-0.04 moL/L of surfactant and 1-4 vt percent of 4-vinylpyridine; or

2vt percent of dilute sulfuric acid, 1vt percent of hydrofluoric acid, 0.005-0.02 moL/L of 4-nitrotetrafluoroboric acid benzene poly-ether, 0.005-0.04 moL/L of surfactant and 1-4 vt percent of 4-vinylpyridine.

Specifically, the step a2 specifically includes:

preparing an activation solution;

and B, placing the sample obtained in the step A1 in a prepared activation solution, continuously stirring for 5-30 min at the temperature of 20-25 ℃, washing with deionized water, and drying.

Preferably, the activating solution comprises 0-0.1 moL/L of nickel chloride hexahydrate, 0.0001-0.001 moL/L of palladium chloride, 20-50 vt% of concentrated hydrochloric acid, and 0.15-0.3 vt% of hydrofluoric acid, or 0-0.1 moL/L of nickel chloride hexahydrate, 0.0001-0.001 moL/L of silver nitrate, 20-50 vt% of concentrated hydrochloric acid, and 0.15-0.3 vt% of hydrofluoric acid.

Preferably, the electroless plating solution comprises a metal salt, a reducing agent and an additive.

The invention also provides a method for chemical plating on the surface of the polymer film, which comprises the steps of grafting functional groups capable of providing chemical adsorption sites for active ions on the surface of the polymer film in a solution, activating in an activating solution, and then performing chemical plating in a chemical plating solution.

In a preferred embodiment, the functional group is a pyridine group.

Specifically, the step of grafting the functionalized group on the surface of the polymer film is to place the polymer film in a functionalized solution containing 4-vinylpyridine and stand for grafting, so that the pyridine group is grafted on the surface of the polymer film.

Specifically, the activation is to place the grafted sample in an activation solution to continuously stir for reaction, wherein the activation solution contains hydrofluoric acid.

Due to the adoption of the technical scheme, compared with the prior art, the invention has the following advantages and positive effects:

(1) the chemical plating method provided by the invention comprises the steps of functionalizing the surface of the polymer film, activating and finally soaking the treated polymer film into chemical plating solution. The surface functionalization is that the surface of the polymer film is grafted with functionalized groups, and the groups can effectively adsorb activated ions, so that the chemical plating is smoothly carried out; in a preferred mode, a pyridine group is grafted on the surface of the polymer, and the pyridine group has a strong adsorption effect on activated ions or atoms and can provide a chemical adsorption site for the activated ions, so that the polymer film has a surface with catalytic activity after being activated, and a metal layer is smoothly plated on the surface of the polymer film; the invention solves the problems that the surface energy of the polymer is low and the polymer can not become a catalytic surface by designing the surface functionalization step, and avoids the negative effects caused by surface roughening and surface plasma treatment;

(2) in the preferred scheme of the invention, hydrofluoric acid is added during the preparation of the activating solution, and reacts with the metal or semiconductor substrate to generate active hydrogen atoms, and the active hydrogen atoms directly reduce the activated ions into activated atoms, thereby enhancing the adsorption effect;

(3) in the preferred embodiment of the invention, the concentration of the palladium chloride or the silver nitrate is only 0.0001-0.001 moL/L, the consumption of the noble metal ions is less than that of the traditional activation solution, a better activation effect can be achieved by using a small amount of the noble metal ions, and the cost is effectively reduced; the operation steps of the invention can be directly carried out at room temperature and in the atmospheric environment, and the invention has the advantages of no equipment requirement, simple operation and low cost.

Drawings

FIG. 1 is a flow chart of a method for chemical plating of a polymer film surface according to the present invention;

FIG. 2 is a schematic diagram of chemical plating of the surface of a polymer film according to the present invention;

FIG. 3 is XPS N1s core spectrum of sample surface after example 2 activation;

FIG. 4 is a scanning electron microscope photograph of the surface of the electroless nickel-phosphorous plating layer of example 2;

FIG. 5 is an X-ray energy spectrum of the surface of the electroless nickel-phosphorous plating layer of example 2.

Detailed Description

The method for chemical plating of a polymer film surface according to the present invention is further described in detail with reference to the accompanying drawings and specific examples. Advantages and features of the present invention will become apparent from the following description and from the claims.

Example 1

Referring to fig. 1, this embodiment provides a method for chemical plating on a surface of a polymer film, where the polymer film may be a majority of organic films such as polymethyl methacrylate (PMMA), polymethacrylic acid (PMAA), Polymethacrylimide (PMI), polyethylene terephthalate (PET), Polyamide (PA), polypropylene (PP), polyvinyl chloride (PVC), polyvinyl alcohol (PVA), and the like, and the thickness of the polymer film may be as low as several hundred nanometers, and the polymer film may be deposited on a metal or semiconductor substrate, and the polymer film may be prepared by a conventional method in the art. The method of the embodiment comprises the following steps:

a1: functionalizing the surface of the polymer film, namely placing the polymer film into a functionalized solution, and standing and grafting for 10-120 min at the temperature of 20-25 ℃ to graft a pyridine group on the surface of the polymer film;

a2: activating the surface of the polymer, namely placing the sample obtained in the step A1 in an activation solution, and continuously stirring for 5-30 min at the temperature of 20-25 ℃ to obtain a polymer film adsorbed with activated ions or atoms;

a3: and D, chemical plating, namely placing the sample obtained in the step A2 in chemical plating solution, adjusting the temperature to a preset temperature, continuously stirring for 15-45 min, and performing chemical plating operation. The chemical plating solution comprises metal salt, a reducing agent and an additive, the stirring time can be determined according to the required plating thickness, and the chemical plating temperature is adjusted according to the metal to be plated and the pH value of the chemical plating solution.

The electroless plating method provided in this embodiment first functionalizes the surface of the polymer thin film, then activates the polymer thin film, and finally soaks the treated polymer thin film into an electroless plating solution. The surface functionalization is that the surface of the polymer film is grafted with functionalized groups, and the groups can effectively adsorb activated ions, so that the chemical plating is smoothly carried out. Referring to fig. 3, in a preferred mode, a pyridine group is grafted on the surface of the polymer, and the pyridine group has a strong adsorption effect on activated ions or atoms and can provide chemisorption sites for the activated ions, so that the polymer film has a catalytically active surface after activation, and the surface of the polymer film is smoothly plated with a metal layer. The invention solves the problems that the surface energy of the polymer is low and the polymer can not become a catalytic surface by designing the surface functionalization step, and avoids the negative effects caused by surface roughening and surface plasma treatment.

Specifically, referring to fig. 2, step a1 specifically includes:

a101: ultrasonically cleaning the polymer film for 30-60 s by using deionized water, and drying;

a102: preparing a functional solution;

a103: placing the polymer film in the functional solution prepared in the step A102, standing and grafting for 10-120 min at the temperature of 20-25 ℃, washing with deionized water, and drying;

wherein, step a101 and step a102 can be performed in an alternative order or simultaneously.

Further, the chemical composition of the functionalization solution is selected from one of:

2vt percent of dilute sulfuric acid, 1vt percent of hydrofluoric acid, 0.005-0.02 moL/L of 4-nitrotetrafluoroboric acid benzene poly-ether, 0.005-0.04 moL/L of surfactant and 1-4 vt percent of 4-vinylpyridine. The pyridine group is provided by 4-vinylpyridine in the functionalized solution, and the pyridine group can be grafted on the surface of the polymer film by placing the polymer film in any one of the solutions.

Specifically, step a2 specifically includes:

a201: preparing an activation solution;

a202: and B, placing the sample obtained in the step A1 in the activation solution prepared in the step A201, continuously stirring for 5-30 min at the temperature of 20-25 ℃, washing with deionized water, and drying.

Further, the activating solution comprises 0-0.1 moL/L of nickel chloride hexahydrate, 0.0001-0.001 moL/L of palladium chloride, 20-50 vt% of concentrated hydrochloric acid, and 0.15-0.3 vt% of hydrofluoric acid, or 0-0.1 moL/L of nickel chloride hexahydrate, 0.0001-0.001 moL/L of silver nitrate, 20-50 vt% of concentrated hydrochloric acid, and 0.15-0.3 vt% of hydrofluoric acid.

The activation treatment is a key step before chemical plating, and the commonly used activation method is divided into two steps, namely, stannous chloride acid solution is adopted for sensitization and then palladium chloride solution is used for activation, but the method has poor adsorption effect on activated ions. In the embodiment, hydrofluoric acid is added into the activation solution, active hydrogen atoms are generated by reaction of the hydrofluoric acid and the substrate, and the activated ions are directly reduced into the activated atoms, so that the activation points are enhanced, and the adsorption effect is increased, therefore, the embodiment can effectively improve the activation effect. In the embodiment, the concentration of the palladium chloride or the silver nitrate is only 0.0001-0.001 moL/L, the consumption of the noble metal ions is less than that of the traditional activation solution, a good activation effect can be achieved by using a small amount of the noble metal ions, and the cost is effectively reduced. In addition, the operation steps of the embodiment can be directly carried out at room temperature and in the atmospheric environment, the equipment requirement is avoided, the operation is simple, and the cost is low. Moreover, after the surface of the polymer film is functionalized, a sensitization step is not needed, the polymer film can be directly activated, and a subsequent reduction step can be omitted, so that the traditional pretreatment process is simplified.

In the following description of the examples, the temperature is not particularly specified to be 25 ℃ at room temperature.

Example 2

The chemical plating of Ni-P alloy on the surface of polymethacrylic acid (PMAA) film includes the following steps:

1. preparing a PMAA film; acetone, alcohol and deionized water are respectively used for the pair of the sizes of 1 multiplied by 2cm²After ultrasonic cleaning, the silicon wafer is immersed into an HF solution with the volume ratio concentration of 5% for Si-H treatment for 3 minutes, the silicon wafer is placed in a prepared grafting solution, grafting reaction is carried out for 30 minutes at room temperature, and then ultrasonic cleaning and drying are carried out by deionized water. And obtaining a PMAA polymer film with the thickness of about 150nm on the surface of the silicon wafer. The preparation method of the grafting solution comprises the following steps: firstly, 50mL of deionized water is added into a beaker, then 0.1g of sodium dodecyl sulfate, 1mL of fluoroboric acid, 0.5mL of hydrofluoric acid, 2mL of methacrylic acid and 0.1g of p-nitrophenyltetrafluoroborate diazonium salt are sequentially added under magnetic stirring, and the mixture is stirred until the mixture is clear.

2. And ultrasonically cleaning the PMAA polymer film for 1min by using deionized water, and drying for later use.

3. Preparing a functional solution:

4. and (3) placing the cleaned sample in a functional solution, standing and grafting for 10min at room temperature, washing with deionized water, and drying.

5. Preparing an activation solution:

6. the sample obtained in step 4 was placed in the activating solution and stirred continuously at room temperature for 20 min.

7. And (3) placing the sample obtained in the step (6) in an acidic chemical plating solution, adjusting the temperature to 80 ℃, carrying out chemical plating for 15min under the condition of continuous stirring, washing with deionized water, and drying. Wherein, the chemical components in the chemical plating solution are nickel sulfate: 25g/l, sodium hypophosphite: 25g/L, sodium citrate: 10g/L, sodium acetate: 10g/L, thiourea: 0.1mg/L, pH: 4.3 to 4.8.

The surface of the sample after activation was analyzed by X-ray photoelectron spectroscopy, and FIG. 3 is a core spectrogram of N1s, from FIG. 3, it can be seen that pyridine group (-C) can be detected on the surface of the sample₅H₅N), indicating that the surface of the PMAA film is successfully grafted with pyridine groups.

The dried sample is observed on the surface of the sample by a scanning electron microscope, namely, a graph 4 shows that the surface of the sample has a uniform and compact film, and a graph 5 shows that the surface of the sample contains nickel and phosphorus atoms, so that a uniform and compact nickel and phosphorus layer is plated on the surface of the PMAA film.

Example 3

The surface of polyacrylic acid (PAA) film is chemically plated with copper, and the steps are as follows:

1. preparing PAA film by mixing 1 × 2cm²The nickel sheet is placed in a chemical grafting solution of PAA, grafting reaction is carried out for 30 minutes at room temperature, and then deionized water is used for ultrasonic cleaning and drying. A PAA polymer film with a thickness of about 150nm was obtained on the surface of the nickel plate. The preparation method of the chemical grafting solution comprises the following steps: firstly, 50mL of deionized water is added into a beaker, then 0.1g of sodium dodecyl sulfate, 1mL of fluoroboric acid, 0.5mL of hydrofluoric acid, 2mL of acrylic acid and 0.1g of p-nitrobenzene tetrafluoroborate diazonium salt are sequentially added under magnetic stirring, and the mixture is stirred until the mixture is clear.

2. Grafting the graft onto the surface of a substrate with the size of 1 multiplied by 2cm²The PAA film is ultrasonically cleaned for 1min by deionized water and is dried for standby.

3. Preparing a functional solution:

4. and (3) placing the sample obtained in the step (2) in the functionalized solution, standing and grafting for 10min at room temperature, washing with deionized water, and drying.

5. Preparing an activation solution:

6. the sample obtained in step 4 was placed in the activating solution and stirred continuously at room temperature for 30 min.

7. And (3) placing the sample obtained in the step (6) in a chemical copper plating solution, adjusting the temperature to 35 ℃, carrying out chemical plating for 30min under the condition of continuous stirring, washing with deionized water, and drying. Wherein the chemical composition of the chemical plating solution is 7.5g/L copper sulfate, 15g/L formaldehyde, 22g/L disodium ethylene diamine tetraacetate, 15g/L potassium sodium tartrate and 10g/L sodium hydroxide.

Through the steps, the surface of the PAA film is provided with a uniform metal copper plating layer.

Example 4

The chemical plating of Ni-B alloy on the surface of polymethyl methacrylate (PMMA) film includes the following steps:

1. preparing PMMA film with the size of 1 multiplied by 2cm²The copper sheet is placed in a chemical grafting solution of PMMA, and after grafting reaction is carried out for 30 minutes at room temperature, deionized water is used for ultrasonic cleaning and drying. A PMMA polymer film with the thickness of about 150nm is obtained on the surface of the copper sheet. The preparation method of the chemical grafting solution comprises the following steps: firstly, 50mL of deionized water is added into a beaker, and then 0.1g of sodium dodecyl sulfate, 1mL of fluoroboric acid, 0.5mL of hydrofluoric acid, and,2mL of methyl methacrylate and 0.1g of p-nitrophenyl tetrafluoroborate diazonium salt, and stirring until clear.

2. Grafting the graft onto the surface of a substrate with the size of 1 multiplied by 2cm²And ultrasonically cleaning the PMMA film by using deionized water for 1min, and drying for later use.

3. Preparing a functional solution:

4. and (3) placing the sample obtained in the step (2) into the solution obtained in the step (3), standing and grafting for 10min at room temperature, washing with deionized water, and drying.

5. Preparing an activation solution:

6. and (3) placing the sample obtained in the step (4) in the solution prepared in the step (5), and continuously stirring at room temperature for 30 min.

7. And (3) placing the sample obtained in the step (6) in an acidic chemical plating solution, adjusting the temperature to 80 ℃, carrying out chemical plating for 30min under the condition of continuous stirring, washing with deionized water, and drying. Wherein the chemical composition of the chemical plating solution is 50g/L of nickel sulfate, 2.5g/L of dimethylamine borane, 25g/L of sodium citrate, 25g/L of lactic acid, 1mg/L of stabilizer and 6 of PH value.

Through the steps, the uniform Ni-B alloy plating layer is obtained on the surface of the PMMA film.

Example 5

The chemical plating of Co-Fe-P alloy on the surface of polymethyl methacrylate (PMMA) film includes the following steps:

1. preparing a PMMA film: acetone, alcohol and deionized water are respectively used for the pair of the sizes of 1 multiplied by 2cm²After ultrasonic cleaning, the silicon wafer is immersed into an HF solution with the volume ratio concentration of 5% for Si-H treatment for 3 minutes, the silicon wafer is placed in a prepared grafting solution, grafting reaction is carried out for 30 minutes at room temperature, and then ultrasonic cleaning and drying are carried out by deionized water. Obtaining a thickness of about150nm PMMA polymer film. The preparation method of the grafting solution comprises the following steps: firstly, 50mL of deionized water is added into a beaker, then 0.1g of sodium dodecyl sulfate, 1mL of fluoroboric acid, 0.5mL of hydrofluoric acid, 2mL of methyl methacrylate and 0.1g of p-nitrophenyltetrafluoroborate diazonium salt are sequentially added under magnetic stirring, and the mixture is stirred until the mixture is clear.

2. The size of the graft to the surface of the substrate is 1X 2cm²And ultrasonically cleaning the PMMA film by using deionized water for 1min, and drying for later use.

3. Preparing a functional solution:

5. Preparing an activation solution:

6. the sample obtained in the step 4 is placed in the solution obtained in the step 4, and stirring is continued for 30min at room temperature.

7. And (3) placing the sample obtained in the step (6) in a chemical plating solution, adjusting the temperature to 80 ℃, carrying out chemical plating for 35min under the condition of continuous stirring, washing with deionized water, and drying. Wherein the chemical composition of the chemical plating solution is cobalt sulfate: 20g/L, ferric sulfate: 10g/L, sodium hypophosphite: 30g/L, sodium citrate: 85g/L, ammonium chloride: 15g/L, manganese sulfate: 5 g/L.

Through the steps, the uniform Co-Fe-P alloy coating is obtained on the surface of the PMMA film.

In the above-mentioned examples, the chemical reagents used were purchased from the market, wherein the selected purchase concentration of fluoboric acid was 40%, the selected purchase concentration of hydrofluoric acid was 40%, and the selected purchase concentration of 4-vinylpyridine was 95%.

As can be seen from the above embodiments, the method for chemical plating on a surface of a polymer film according to the present invention includes grafting a functional group capable of providing a chemisorption site for an active ion onto the surface of the polymer film in a solution, activating the polymer film in an activation solution, and performing chemical plating in the chemical plating.

In a preferred embodiment, the functionalizing group is a pyridine group.

The embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the present invention is not limited to the above embodiments. Even if various changes are made to the present invention, it is still within the scope of the present invention if they fall within the scope of the claims of the present invention and their equivalents.

Claims

1. A method of chemical plating a surface of a polymer film, comprising:

a3: chemical plating: placing the sample obtained in the step A2 in a chemical plating solution, adjusting the temperature to a preset temperature, continuously stirring for 15-45 min, and performing chemical plating operation;

the step a1 specifically includes:

cleaning and drying the polymer film;

placing the polymer film in a prepared functional solution, standing and grafting for 10min at the temperature of 20-25 ℃, washing with deionized water, and drying;

the chemical composition of the functionalization solution is selected from one of the following:

2vt percent of dilute sulfuric acid, 1vt percent of hydrofluoric acid, 0.005-0.02 moL/L of 4-nitrotetrafluoroboric acid benzene poly-p-phenylene, 0.005-0.04 moL/L of surfactant and 1-4 vt percent of 4-vinylpyridine;

the step a2 specifically includes:

preparing an activation solution;

placing the sample obtained in the step A1 in a prepared activation solution, continuously stirring for 5-30 min at the temperature of 20-25 ℃, washing with deionized water, and drying;

the activating solution comprises 0-0.1 moL/L nickel chloride hexahydrate, 0.0001-0.001 moL/L palladium chloride, 20-50 vt% concentrated hydrochloric acid and 0.15-0.3 vt% hydrofluoric acid, or 0-0.1 moL/L nickel chloride hexahydrate, 0.0001-0.001 moL/L silver nitrate, 20-50 vt% concentrated hydrochloric acid and 0.15-0.3 vt% hydrofluoric acid.

2. The method of surface chemical plating of polymer films according to claim 1, wherein the electroless plating solution comprises a metal salt, a reducing agent, and an additive.