TWI532886B - A chemical copper plating solution for ag-catalysed copper deposition process and a method of using the chemical copper plating solution for ag-catalysed copper deposition process thereof - Google Patents

Description

Electroless copper plating solution for silver catalyst copper plating reaction and chemistry for using copper catalyst for copper catalyst reaction Method for copper plating of silver catalyst by copper plating solution

The invention relates to an electroless copper plating solution, in particular to an electroless copper plating solution for copper catalyst copper plating reaction, and the invention further comprises an electroless copper plating solution using the silver catalyst copper plating reaction for silver catalyst plating. The method of copper.

The electroless copper plating reaction is widely used in the industry today due to its simple operation. The electroless copper plating reaction uses a substrate as a working electrode and is placed in an electroless copper plating solution, and copper ions in the electroless copper plating solution are deposited on the surface of the substrate by energization to form a copper plating film. The material can be a printed circuit board or plastic, and is electrolessly plated to obtain a substrate having good electrical conductivity. In the electroless copper plating reaction, the rate of the electroless copper plating reaction is often increased by a palladium catalyst. When palladium is used as a catalyst for the electroless copper plating reaction, an accelerator is often added to the electroless copper plating solution. Or a stabilizer, and a compound such as 1,10-phenanthroline or bipyridine is reported in the literature as a stabilizer in the electroless copper plating solution to effectively and accurately control the reaction rate. However, since palladium is a precious metal, the price is quite high, and the price of international precious metals often fluctuates with the international situation, causing the process cost of electroless copper plating using palladium as a catalyst to fluctuate. The medium is used in the electroless copper plating reaction. The price of silver is much lower than that of palladium. Therefore, the use of silver catalyst for electroless copper plating has become a new trend in the industry.

The electroless copper plating solution used for the silver catalyst copper plating reaction contains copper sulfate, one still The original agent and a chelating agent, and the above compound is dissolved in water. However, due to the poor reaction efficiency of the silver catalyst copper plating using the electroless copper plating solution for the silver catalyst copper plating reaction, the copper ions can be deposited on the substrate only at a slow rate, which is not only elongated to have the copper. The working time of the coated substrate is also prone to short-circuiting, which causes the reaction to be interrupted by the short circuit during the reaction, resulting in uneven thickness and poor quality of the formed copper plating film.

In view of the above, it is necessary to provide an electroless copper plating solution for the copper catalyst copper plating reaction to solve the problems of low reaction efficiency and poor coating quality of the silver plating reaction by silver catalyst.

The present invention provides an electroless copper plating solution for a copper catalyst copper plating reaction, which can increase the rate of performing an electroless copper plating reaction.

The invention provides an electroless copper plating solution for copper catalyst copper plating reaction, which can avoid the occurrence of short circuit to improve the coating quality.

An electroless copper plating solution for silver catalyst copper plating reaction, comprising: a copper ion source for providing copper ions; and a reducing agent for reducing copper ions to metal Copper; a chelating agent for chelation with copper ions; an accelerator, the accelerator having a nitrogen-containing heterocyclic ring; and a solvent for mixing the copper ion source The reducing agent, the chelating agent and the accelerator, wherein the accelerator is 1,10-phenanthroline, bipyridine, 2,9-methylene-1,10-phenanthroline, tripyridine or 4 - Hydroxypyridine, the concentration of the copper ion source is 0.01 to 0.2 M, the concentration of the reducing agent is 0.05 to 0.2 M, the concentration of the chelating agent is 0.05 to 0.2 M, and the concentration of the accelerator is 1 × 10 ^-6 ~ 1×10 ^-5 M, the copper ion source is copper sulfate, copper nitrate, copper chloride, copper carbonate, copper tartrate, copper hydroxide or copper acetate, the reducing agent is formaldehyde, polyoxymethylene, sodium hypophosphite, hydroboration Sodium, potassium borohydride, dimethylamine borane or glucose, the chelating agent is ethylenediaminetetraacetic acid, ammonia diacetic acid, ammonia triacetic acid, N-hydroxyethyl B Amine triacetate, sodium potassium tartrate, sodium gluconate, triethanolamine, glycerol, tetrahydroxypropyl ethylene diamine, hydroxy - (1,1) - ethylene diphosphate or trimethylene amino acid.

An electroless copper plating solution for a copper catalyst copper plating reaction, wherein the electroless copper plating solution for the silver catalyst copper plating reaction has a pH of 11 to 13.

A silver catalyst copper plating method comprises: providing a working electrode, the working electric level surface has a silver catalyst; and placing the working electrode into an electroless copper plating solution for a silver catalyst copper plating reaction, Performing electroless plating, wherein the electroless copper plating solution for the silver catalyst copper plating reaction comprises a copper ion source, a reducing agent, a chelating agent and an accelerator, the accelerator having a nitrogen-containing heterocyclic ring a compound, wherein the accelerator is 1,10-phenanthroline, bipyridine, 2,9-methylene-1,10-phenanthroline, tripyridine or 4-hydroxypyridine, and the concentration of the copper ion source is 0.01~0.2M, the concentration of the reducing agent is 0.05~0.2M, the concentration of the chelating agent is 0.05~0.2M, and the concentration of the accelerator is 1×10 ^-6 ~1×10 ^-5 M, the copper ion source It is copper sulfate, copper nitrate, copper chloride, copper carbonate, copper tartrate, copper hydroxide or copper acetate. The reducing agent is formaldehyde, polyoxymethylene, sodium hypophosphite, sodium borohydride, potassium borohydride, dimethylamine boron. Alkane or glucose, the chelating agent is ethylenediaminetetraacetic acid, ammonia diacetic acid, ammonia triacetic acid, N-hydroxyethyl ethylenediamine triacetic acid, sodium potassium tartrate, Grape sugar, sodium, triethanolamine, glycerol, tetrahydroxypropyl ethylene diamine, hydroxy - (1,1) - ethylene diphosphate or trimethylene amino acid.

The electroless copper plating solution for the silver catalyst copper plating reaction of the invention comprises an accelerator, thereby achieving the effect of increasing the rate of the silver catalyst copper plating reaction.

The electroless copper plating solution for the silver catalyst copper plating reaction of the invention can avoid the occurrence of short circuit, thereby improving the coating quality.

The electroless copper plating solution for the silver catalyst copper plating reaction of the invention can shorten the time of the electroless copper plating reaction by using the accelerator, and can perform the copper catalyst copper plating reaction with lower energy, thereby saving the chemical The energy required for the copper plating reaction.

The electroless copper plating solution for the silver catalyst copper plating reaction of the invention utilizes the accelerator to shorten the time of the electroless copper plating reaction, reduce the personnel and time cost of performing the silver catalyst copper plating reaction, and thereby reduce the electroless copper plating reaction. The cost of the effect.

Fig. 1 is a copper plating part A1~A4 of the electroless copper plating liquid for the silver catalyst copper plating reaction of the present invention, an electroless copper plating liquid without the accelerator, and a copper plated part of the A5 combination. XRD diagram.

Fig. 2 is a SEM image of a group A1 of a copper plating material for electroless copper plating of a silver catalyst for copper catalyst reaction.

Fig. 3 is a SEM image of the A2 group of the copper plated material for the electroless copper plating solution for the silver catalyst copper plating reaction of the present invention.

Fig. 4 is a SEM image of a group A3 of the copper plating material for electroless copper plating of the silver catalyst for copper catalyst reaction of the present invention.

Fig. 5 is a SEM image of a group A4 of the copper plating material for electroless copper plating of the silver catalyst for copper catalyst reaction of the present invention.

Fig. 6 is a SEM image of a group A5 of a copper plated material prepared by electroless copper plating without the addition of the accelerator.

Fig. 7 is a cyclic voltammogram of the group B1 to B4 of the electroless copper plating solution for the silver catalyst copper plating reaction of the present invention and the electroless copper plating liquid group B5 which is not added with the accelerator.

Fig. 8 is a graph showing changes in oscillation frequency of the electroless copper plating solution C1 to C4 for the silver catalyst copper plating reaction and the electroless copper plating liquid C5 group to which the accelerator is not added.

Fig. 9 is an open circuit potential diagram of the group C1 to C4 of the electroless copper plating solution for the silver catalyst copper plating reaction of the present invention and the electroless copper plating liquid group C5 to which the accelerator is not added.

Fig. 10 is a graph showing the oscillation frequency variation of the electroless copper plating solution of the present invention for the electroless copper plating solution of the silver catalyst in the D1 to D3 groups.

Fig. 11 is an open circuit potential diagram of the group D1 to D3 of the electroless copper plating solution for the silver catalyst copper plating reaction of the present invention.

Fig. 12 is a graph showing the graph of the Gf group of the electroless copper plating solution G1 group for the silver catalyst copper plating reaction and the electroless copper plating liquid G2 group to which the accelerator is not added.

Fig. 13 is a SEM image of a copper plating member obtained by using the electroless copper plating solution for the silver catalyst copper plating reaction in the present invention in a reaction time of 10 seconds.

Fig. 14 is a SEM image of a copper plated article obtained by using the electroless copper plating solution for the silver catalyst copper plating reaction in the present invention in a reaction time of 20 seconds.

Fig. 15 is a SEM image of a copper plating member obtained by using the electroless copper plating solution for the silver catalyst copper plating reaction in the present invention in a reaction time of 50 seconds.

Fig. 16 is a SEM image of a copper plating member obtained by using the electroless copper plating solution for the silver catalyst copper plating reaction in the present invention in a reaction time of 100 seconds.

Figure 17 is a SEM image of a copper plated piece obtained by adding an electroless copper plating solution of the accelerator to a reaction time of 10 seconds.

Figure 18: SEM image of a copper plated piece obtained by adding an electroless copper plating solution of the accelerator to a reaction time of 100 seconds.

The above and other objects, features and advantages of the present invention will become more <RTIgt; The electroless copper plating solution for copper plating reaction comprises a copper ion source containing copper ions; a reducing agent for reducing copper ions to metallic copper; a chelating agent, the chelating agent For chelation with copper ions; an accelerator, the compound having a nitrogen-containing heterocycle; and a solvent for mixing the copper ion source, the reducing agent, the chelating agent, and the acceleration Agent.

In particular, the copper ion source is used to provide copper ions, which are copper compounds used in general electroless copper plating reactions, in particular, copper compounds which can be dissolved in the solvent and freely form copper ions. The copper ion source may be copper sulfate, copper nitrate, copper chloride, carbon Acid copper, copper tartrate, copper hydroxide or copper acetate, etc., in this case, the type of copper ion source is not limited, and a copper ion source with higher purity is preferably used to avoid the influence of impurities on the plating property. In the examples, the copper ion source is copper sulfate, and the purity of the copper sulfate used is 97.5%.

The reducing agent is a compound capable of providing electrons, and the reducing agent is used to supply electrons to the copper ions of the copper ion source to reduce copper ions to form metal copper and deposit on a substrate. The reducing agent may be a compound such as formaldehyde, polyoxymethylene, sodium hypophosphite, sodium borohydride, potassium borohydride, dimethylamine borane or glucose. In the present embodiment, the utility model has the advantages of low price, wide application range and reduction. As a reducing agent, Lijia's formaldehyde has a purity of 24%.

The chelating agent is used for chelation with copper ions in the copper ion source, and the chelating agent may be ethylenediaminetetraacetic acid (EDTA), ammonia diacetic acid, ammonia triacetic acid, N-hydroxyethyl ethylenediamine Acetic acid, sodium potassium tartrate, sodium gluconate, triethanolamine, glycerol, tetrahydroxypropyl ethylene diamine, hydroxy-(1,1)-ethylene diphosphate (HEDP) or aminotrimethylene phosphate (ATMP), In this embodiment, the chelating agent is ethylenediaminetetraacetic acid.

The accelerator is used to accelerate the silver catalyst copper plating reaction, and the accelerator is a compound having a nitrogen-containing hetero ring, and the accelerator has a non-localized π bond, when the accelerator is adsorbed on the surface of the silver catalyst and Forming a complex with copper ions will contribute to the transfer of electrons. Preferably, the accelerator is a compound having two nitrogen-containing heterocycles, which can accelerate the progress of the silver catalyst copper plating reaction more greatly. In particular, the accelerator may be 1,10-phenanthroline, bi-2'-bipyridine, 2,9-methylene-1,10-phenanthroline. (Neocuproine), a compound having a nitrogen-containing hetero ring such as tripyridine (2,2':6',2"-Terpyridine) or 4-hydroxypyridine.

The solvent is used to mix the copper ion source, the reducing agent, the chelating agent and the accelerator, so that the above compounds can be uniformly in the solvent, and the solvent system can be water, but not limited thereto. . The solvent for the electroless copper plating solution for the silver catalyst copper plating reaction of the present embodiment is deionized water, which is manufactured by Millipore Milli-Q ultrapure water machine, and the deionized water is charged at 25 ° C. The resistance is 18.2 MΩ×cm.

The electroless copper plating solution for the silver catalyst copper plating reaction of the present invention comprises the copper ion source having a concentration of 0.01 to 0.2, the reducing agent having a concentration of 0.05 to 0.2 M, and the chelating agent having a concentration of 0.05 to 0.2 M. And the accelerator having a concentration of 1×10 ^-6 to 1×10 ⁻⁵ M, preferably, the formaldehyde has the ability to reduce copper ions at a pH of more than 11, and the pH is greater than 13 The composition of the electroless copper plating solution of the silver catalyst copper plating reaction is decomposed, resulting in poor stability. Therefore, the pH of the electroless copper plating solution for the silver catalyst copper plating reaction is adjusted by sodium hydroxide to about 11-13. The pH of the electroless copper plating solution for the silver catalyst copper plating reaction can also be adjusted by using potassium hydroxide, sulfuric acid or other organic acid. In this embodiment, the electroless copper plating solution for the silver catalyst copper plating reaction comprises the copper ion source having a concentration of 0.1 M, the reducing agent having a concentration of 0.1 M, the chelating agent having a concentration of 0.1 M, and The accelerator having a concentration of 3.2 × 10 ^-5 M has a pH of 12.3 for the electroless copper plating solution for the silver catalyst copper plating reaction.

The invention further comprises a silver catalyst copper plating reaction using the electroless copper plating solution for the silver catalyst copper plating reaction, wherein the silver catalyst copper plating reaction system comprises a substrate having a silver catalyst adsorbed on the surface of the substrate. And placing the substrate into the electroless copper plating solution for the silver catalyst copper plating reaction to perform an electroless copper plating reaction to obtain a copper plated member having a copper plating layer on the surface.

The silver catalyst copper plating reaction in this embodiment is a redox reaction composed of two semi-reactive formulas, including an oxidation reaction of an anode and a copper ion reduction reaction of a cathode, and the reaction formulas thereof are respectively listed in the following formula ( 1) and the following formula (2), the following formula (3) is the full reaction type: anode reaction formula: 2HCHO + 4OH ^- → 2HCOO ^- + H ₂ + 2H ₂ O + 2e ^- ... (1)

Cathodic reaction formula: Cu ²⁺ +2e ^- → Cu... (2)

Full reaction formula: Cu ²⁺ +2HCHO+4OH ^- → Cu+2HCOO ^- +2H ₂ O+H ₂ (3)

In the silver catalyst copper plating reaction, the silver catalyst mainly catalyzes the emission of electrons by the formaldehyde, so that the copper ions in the electroless copper plating solution for the silver catalyst copper plating reaction receive the electrons emitted by the formaldehyde and undergo a reduction reaction. The metal copper is deposited on the substrate, so the catalytic reaction of the silver catalyst to formaldehyde affects the copper plating rate and catalytic activity of the silver catalyst copper plating reaction, and the nitrogen atom of the nitrogen-containing heterocyclic ring in the accelerator forms on the surface of the silver nanoparticle. The bonding of Ag-N changes the electrostatic structure of the silver catalyst surface during the chemisorption process and accelerates the generation of CH ₂ (OH)O- and desorbs the charge transfer of HCOO-reinforced metal, affecting the silver catalyst copper plating reaction. And increase the oxidation of formaldehyde.

Taking the accelerator as 1,10-phenanthroline as an example, the process of copper plating in the silver catalyst is a process of complexing with a silver ion ligand through a lone pair of electrons contained in a nitrogen atom, and chemical adsorption by a ligand. On the surface of the silver catalyst, Ag-N stretching bands are formed with the silver catalyst, and the chemical interaction mechanism and the atomic scale (Atomic-scale) active sites are enhanced, and the metal ligands are combined with the metal ligands. The vertical angles are connected to change the electrostatic structure of the silver catalyst surface, accelerate the adsorption of free radicals (CH2(OH)O-) and the desorption of HCOO-, thereby increasing the oxidation and electroless plating kinetics of formaldehyde.

The electroless copper plating solution for the silver catalyst copper plating reaction of the present invention comprises the accelerator, the accelerator is a compound containing a nitrogen-containing heterocycle, and the accelerator has a non-localized π bond, when the accelerator adsorbs On the surface of the silver catalyst and forming a complex with the divalent copper ions, it will contribute to the electron transfer, so that the rate of the copper catalyst copper plating reaction can be effectively improved, and the short circuit condition can be avoided to improve the copper plating film. Quality, in addition, the use of the electroless copper plating solution for the silver catalyst copper plating reaction can save the energy required for the silver catalyst copper plating reaction, and achieve the effect of reducing the cost of the silver catalyst copper plating reaction; By using the copper ion source, the reducing agent, the chelating agent and the specific concentration of the accelerator, the time required for the reaction can be further saved, thereby achieving the effect of reducing the time cost of production.

In order to confirm that the electroless copper plating system for the silver catalyst copper plating reaction of the present invention can increase the reaction rate of the silver catalyst copper plating reaction, the following tests are carried out, and it should be noted that The silver catalyst used in the test is a silver nitrate particle obtained by co-reacting silver nitrate, polyvinylpyrrolidone and hydrazine. The average particle size of the silver nanoparticle is about 34±5 nm, which is before the start of the test. Depositing the silver nanoparticle on a working electrode surface, and immersing the working electrode in the electroless copper plating solution for the silver catalyst copper plating reaction of the present invention to form the surface of the working electrode Copper plating:

(A) XRD diffraction pattern and SEM image of copper plating

The electroless copper plating solution for the silver catalyst copper plating reaction of the present test comprises the copper ion source having a concentration of 0.05 M, the reducing agent having a concentration of 0.1 M, the chelating agent having a concentration of 0.1 M, and a concentration of 3.2×. 10 to ⁵ M of the accelerator, the copper ion source is copper sulfate, the reducing agent is formaldehyde, the chelating agent is EDTA, and the type of the accelerator is changed to 1,10-phenanthroline, 2,9-Asia Methyl-1,10-phenanthroline, tripyridine and 4-hydroxypyridine were used as a control group without adding any one of the accelerators for the silver catalyst copper plating reaction. Copper plated parts A1, A2, A3, A4 and A5, and the composition and lattice arrangement of the copper plating of the copper plated parts were analyzed by x-ray diffraction spectroscopy, as shown in Fig. 1. As shown, in this test, the surface morphology of the A1 to A5 groups of the copper-plated parts was further observed by an electron microscope, as shown in the second to sixth figures.

From the XRD diffraction pattern of Fig. 1, the copper plating layer synthesized by the group A1~A5 can be known, and the copper plating layer is grown in the lattice direction of (11), and the structure of the copper plating layer is face-centered cubic. Stacking (FCC), since the copper plating is grown in the (111) direction, the copper plating layer has high ductility and low electrical resistivity. Please also refer to the second to sixth figures. Compared with the A3~A5 group, the copper plating layer has larger pores and the surface morphology is uneven. The distribution of the copper plating layer formed by the combination of A1 and A2 is average. And can be uniformly coated on the surface of the working electrode, so the copper plating system synthesized by using 1,10-phenanthroline and 2,9-methylene-1,10-phenanthroline as the accelerator It has better coating properties. In addition, it can be known from the SEM images of A1 to A5 that the addition of the accelerator to the electroless copper plating solution for the copper plating reaction of the silver catalyst does cause the copper plating of the copper plating member to have an appearance. Change, which in turn changes the uniformity and coverage of the copper plating of the copper plated part Degree of coating quality.

(B) Cathodic cyclic voltammetry analysis

In this test, a three-stage electrolytic cell is used for electrochemical analysis, and the working electrode, a counter electrode and a reference electrode are disposed in the electrolytic cell, and the working electrode has a surface area of 0.159 cm ² of glassy carbon electrode, the corresponding electrode is a platinum piece, the reference electrode is a saturated calomel electrode (Hg/Hg ₂ Cl ₂ ), and the surface of the working electrode is coated with a weight density of 30 μg /cm ² of silver nanoparticles, the anolyte of the test is 0.1M of the reducing agent, 0.1M of the chelating agent and 3.2×10 ^-5 M of the accelerator, the catholyte concentration is 0.05 a copper ion source of M, 0.1 M of the reducing agent, 0.1 M of the chelating agent, and 3.2×10 ^-5 M of the accelerator, and the catholyte and the anolyte are all adjusted to a pH of 12.3 using sodium hydroxide. The copper ion source is copper sulfate, the reducing agent is formaldehyde, the chelating agent is EDTA, and the accelerator type in the anolyte is 1,10-phenanthroline, 2,9-methylene-1, 10-phenanthroline, tripyridine and 4-hydroxypyridine, and no addition of any accelerator Electrolytic solution as a control group, to sequentially obtain the copper member of Group B1, Group B2 first, the first group B3, B4 first group and second group B5, 5mVs ^-1 at a scan rate of cyclic voltammetry (cyclic voltammetry) Test, the results are shown in Figure 7. In order to remove the interference of oxygen on the test results, the test was carried out with saturated nitrogen gas into the anolyte and catholyte maintained at 30 ° C for 20 minutes, and the nitrogen gas was saturated with nitrogen gas during the test. status.

The oxidation peak appearing at a potential of -0.43 V (vs. SCE) is a characteristic peak of the formation of monovalent copper (Cu(I)), and the oxidation peak appearing at a potential of -0.21 V (vs. SCE) is a bivalent formation. Copper (Cu(II)) and oxidized to form a characteristic peak of copper oxide, while the reduction peak at a potential of -0.37V (vs. SCE) is a characteristic peak of copper oxide free, and the potential is -0.68V (vs. SCE). The reduction peak is a characteristic peak of reduction of copper (Cu(II)) to metallic copper, and the reduction peak of -0.96V (vs. SCE) is a characteristic peak produced by the mismatch of copper and chelating agent. It can be seen from the observation in Figure 7, compared to the B5 In the group, the B1~B4 group can inhibit the formation of copper oxide and accelerate the dissociation of the complex compound. Since the precipitation of copper oxide will have a negative impact on the rate of the electroless copper plating reaction, the faster the dissociation speed of the complex compound is beneficial. Cathodic reduction of the complex compound, as a result, it can be proved that the reaction rate of the B1 to B4 group as the anolyte system for the electroless copper plating reaction of the silver catalyst is helpful, especially in the case of the accelerated reaction of the B1 group. Most prominent in all groups.

(C) Oscillation frequency change and open circuit potential test of silver catalyst electroless copper plating reaction with different accelerators

This experiment is based on the kinetic analysis of the electrochemical copper crystal micro-scale to shape the silver catalyst copper plating reaction. The working electrode of this experiment is quartz crystal micro-scale, the crystal material of quartz crystal micro-scale is the gold quartz piece with the area of 0.159cm2. The reference electrode is a saturated calomel electrode of a Luggin capillary, and the surface of the working electrode is coated with silver nanoparticle having a weight density of 30 μg/cm ² , and the working electrode and the reference electrode are placed on The electroless copper plating solution for the silver catalyst copper plating reaction of the present invention is connected with an electric current, and the electroless copper plating liquid for the silver catalyst copper plating reaction comprises a 0.05 M copper ion source and a 0.1 M reducing agent. 0.1M chelating agent is 3.2×10 ^-5 M accelerator, the copper ion source is copper sulfate, the reducing agent is formaldehyde, the chelating agent is EDTA, and the type of the accelerator is adjusted to 1,10-firo Porphyrin (Group C1), 2,9-methylene-1,10-phenanthroline (Group C2), tripyridine (Group C3) and 4-hydroxypyridine (Group C4), and no addition Any anolyte of the accelerator is used as a control group (Group C5), and an electroless copper deposition reaction is performed to obtain an oscillation frequency. Changes and results of the open-circuit potential, the results sequentially as shown in FIGS. 8 and 9. In order to remove the interference of oxygen on the test results, the test was carried out with saturated nitrogen gas into the electroless copper plating solution of the silver catalyst copper plating reaction at 30 ° C for 20 minutes, and the test was continued with a trace of nitrogen gas. Make sure the nitrogen is saturated.

Please refer to Figure 8 firstly, the sedimentation dynamics of silver nanoparticles can be shown by the change of oscillation frequency, which can be divided into the incubation period with no significant change in frequency and the acceleration period with accelerated change of frequency (Acceleration). Period) two stages, by figure 9 It can be seen that the change of C1~C3 after 15 seconds of reaction is larger than that of the C4 and C5 groups, and the change of the oscillation frequency of the C1 group after 15 seconds of reaction is particularly obvious.

Continuing with reference to Fig. 9, when the electroless copper plating reaction is carried out, a steady-state mixed potential (Steady-state Mixed-potential) is first passed after a non-steady time, and deposition is started after the mixed potential is reached. The reaction, starting from an unsteady to steady state deposition reaction, is called the Induction period. Since the length of the lead time will affect the industrial time cost of the silver catalyst electroless copper plating reaction, the ideal electroless copper plating reaction should have a shorter lead time. It can be clearly seen from Fig. 9 that the lead time of the C1 group is significantly shorter than that of the other groups. In detail, the open circuit potential of the silver catalyst copper plating reaction of the C1 group is used after the start of the reaction. Move negatively to the first mixed potential (E _mp =-0.55V (vs. SCE)) and quickly reach a more negative stable mixed potential (-0.68V (vs. SCE)) after about 15 seconds from the start of the reaction. And begin the deposition reaction. More specifically, the first mixed potential is the active center, so it is slower and requires a longer reaction time. When the surface of the silver catalyst covers a certain degree of active center, it will promptly initiate the reaction to reach the steady-state mixed potential. The adsorption of the accelerator on the surface of the silver catalyst has changed the electric double layer structure and the effective area of the working electrode, and introduced a new electrostatic force on the interface between the working electrode and the electroless copper plating solution to reduce the oxidation product of formaldehyde or other oxidation. The formation of intermediate products, thereby increasing the rate of electroless copper plating reaction of silver catalyst.

(D) Oscillation frequency change and open circuit potential test of silver catalyst electroless copper plating with different concentrations of 1,10-phenanthroline as accelerator

It is known from test (C) that the incubation period and the lead time of the electroless copper plating solution using the 1,10-phenanthroline as the accelerator for the silver catalyst electroless copper plating reaction are short, which can effectively save the electrochemical reaction time. In this test, different concentrations of 1,10-phenanthroline were used as accelerators. In the electroless copper plating solution of the silver catalyst electroless copper plating, the concentration of 1,10-phenanthroline was 1.6×10 ^{- 5} M (Group D1), 3.2×10 ^-5 M (Group D2) and 6.4×10 ^-5 M (Group D3), and follow the test method described in Test (C) for silver catalyst chemistry The copper plating reaction was carried out to obtain the test results of the oscillation frequency change and the open circuit potential, and the results were as shown in Figs. 10 and 11.

From Figures 10 to 11, it can be found that the D1~D3 group has a shorter latency and lead time than the C2~C5 group in the test (C), and the concentration of 1,10-phenanthroline is 3.2. At ×10 ^-5 M, it quickly enters the acceleration phase 15 seconds after the start of the reaction, which is significantly faster than the other concentrations (Groups D1 and D3), and is found in the open circuit potential plot of Figure 11, when 1,10 When the concentration of phenanthroline is 3.2×10 ^-5 M, the steady state potential can be reached as soon as possible to continue the copper plating deposition reaction.

(E) Analysis of average mass activity and average deposition rate of different accelerators

In this analysis, the accelerator was selected from 1,10-phenanthroline (Group E1), bipyridine (Group E2), 2,9-methylene-1,10-phenanthroline (Group E3), Pyridine (Group E4), 4-hydroxypyridine (Group E5) and electroless copper plating solution of silver catalyst electroless copper plating without addition of the accelerator (Group E6), and according to the resulting oscillation frequency change results Further calculating the mass activity and the average deposition rate of the electroless copper plating solution obtained by using the silver catalyst electroless copper plating reaction of different accelerators ( ). First, the weight (mg) of copper deposition is calculated by the following formula (4). In the formula (4), Δm is the weight (g) of the deposited copper, ΔF is the change of the oscillation frequency of the quartz crystal, and A is a gold quartz piece. Area (ie 0.159cm ² ), μ is the quartz crystal shear modulus (ie 2.947×1011gcm ^-1 s ^-2 ), ρ is the quartz crystal density (ie 2.648g/cm ³ ), F0 is the quartz crystal oscillation basic Frequency, and then the weight of copper deposition is carried into m _{Cu of the} following formula (5) to calculate the mass activity. In the formula (5), m _Ag is the weight (mg) of the silver catalyst, and then further by the following formula (6) ) to obtain average mass activity ( N in the formula (6) is the total mass activity, since the deposition time in the test (C) is 110 seconds, and a value of mass activity is recorded every 0.1 second, the N in the test is 1100, and finally The average deposition rate was calculated according to the following formula (7). The time _sum in the formula (7) is the total deposition time of each mass activity, and the time _sum of the test is 60555 seconds. The average mass activity and average deposition rate obtained by the analysis are listed in Table 1 below.

The analysis results in Table 1 show that the order of the average mass activity and the average deposition rate from the largest to the smallest are the E1 group, the E2 group, the E3 group, the E4 group, the E5 group and the E6 group, which proves Reaction of 1,10-phenanthroline, bipyridine, 2,9-methylene-1,10-phenanthroline, tripyridine and 4-hydroxypyridine compared to Group E5 without any accelerator added The rate is obviously increased, thereby confirming that the electroless copper plating solution for the silver catalyst copper plating reaction of the present invention can accelerate the copper catalyst copper plating reaction due to the accelerator contained therein, wherein the accelerator is further accelerated. 1,10-phenanthroline has the highest average mass activity and average deposition rate.

(F) Different concentrations of 1,10-phenanthroline as a catalyst for the electroless copper plating of silver catalyst Analysis of average mass activity and average deposition rate of accelerator

This test and test (E) use the same analytical method, the molar concentration of the accelerator is 1.6 × 10 ^-5 M of 1,10-phenanthroline (Group F1), 3.2 × 10 ^-5 M of 1 , 10-phenanthroline (Group F2) and 6.4×10 ^-5 M 1,10-phenanthroline (Group F3) were analyzed for average mass activity and average deposition rate, and the results are shown in Table 2 below.

The results shown in Table 2 show that the average mass activity and the average deposition rate of the F1 to F3 groups are higher than those of the E6 group in which the accelerator (E) is not added, and it is confirmed that 1,10-phenanthroline is used. The accelerator can indeed accelerate the rate of the electroless copper plating reaction of the silver catalyst. Among them, the reaction rate of the 1,10-phenanthroline having a concentration of 3.2×10 ^-5 M as the accelerator is the fastest.

(G) Tarver curve analysis

This analysis is for the silver catalyst copper plating reaction of the accelerator with a molar concentration of 3.2 × 10 ^-5 M 1,10-phenanthroline (Group G1) and no accelerator (G2 group). The electroless copper plating solution is subjected to linear voltammetry to obtain a polarization curve, and the current value is obtained by dividing the current value by the real electrochemical active area, and the current density is taken as a logarithmic value and plotted against the reaction overpotential, that is, The graph of the Tarver shown in Fig. 12. It can be seen from Fig. 12 that the overpotential of the G1 group is lower than that of the G2 group, and it is confirmed that the addition of 1,10-phenanthroline as an accelerator has the ability to accelerate the catalysis of formaldehyde.

(H) SEM image of copper plating obtained by different reaction times

This analysis is based on an electroless copper plating reaction of an electroless copper plating solution for a silver catalyst for copper plating of a catalyst having a molar concentration of 3.2 × 10 ^-5 M of 1,10-phenanthroline, and adjusting The reaction time is 10 seconds, 20 seconds, 50 seconds, and 100 seconds to obtain the copper plating layer. The SEM image of the copper plating layer is sequentially shown in Figures 13 to 16, and the accelerator is also not added. The electroless copper plating solution of the silver catalyst electroless copper plating reaction is subjected to a silver catalyst electroless copper plating reaction, and the copper plating layer is obtained after the reaction for 10 seconds and 100 seconds, and the SEM image of the copper plating layer is sequentially as shown in FIGS. 17-18. Shown.

It is known from Figures 13 to 16 that copper deposition started 20 seconds after the start of the reaction, and when the reaction proceeded to 100 seconds, the copper deposition was more pronounced, and the 17th to 18th images were not observed to have obvious copper. Deposition occurs, which proves that the addition of the accelerator can cause copper deposition to be apparent within 100 seconds. The accelerator does help to increase the reaction rate of the silver catalyst electroless copper plating reaction, which will help reduce production in industrial applications. Time cost.

In summary, the electroless copper plating solution for the silver catalyst copper plating reaction of the present invention comprises the copper ion source, the reducing agent, the chelating agent and the accelerator, and the accelerator has a nitrogen-containing impurity. The compound of the ring can effectively increase the rate of copper catalyst copper plating reaction to accelerate the electroless copper plating reaction of the silver catalyst; in addition, the electroless copper plating for the silver catalyst copper plating reaction containing the accelerator The liquid can maintain the rate of the electroless copper plating reaction of the silver catalyst to avoid the short circuit in the reaction process, thereby improving the coating quality; further, the electroless copper plating for the silver catalyst copper plating reaction of the present invention The liquid system can shorten the time of the copper catalyst copper plating reaction, thereby achieving the energy and process cost of saving the silver catalyst electroless copper plating reaction. Moreover, in the present invention, the specific concentration of the copper ion source, the reducing agent, the chelating agent and the accelerator can further save the time required for the reaction, thereby achieving the effect of reducing the time cost of production.

While the invention has been described in connection with the preferred embodiments described above, it is not intended to limit the scope of the invention. The technical scope of the invention is protected, and therefore the scope of the invention is defined by the scope of the appended claims.

Claims (3)

An electroless copper plating solution for silver catalyst copper plating reaction, comprising: a copper ion source for providing copper ions, the copper ion source is copper sulfate, copper nitrate, copper chloride, carbonic acid Copper, copper tartrate, copper hydroxide or copper acetate; a reducing agent for reducing copper ions to metallic copper, the reducing agent is formaldehyde, polyoxymethylene, sodium hypophosphite, sodium borohydride, potassium borohydride , dimethylamine borane or glucose; a chelating agent for chelation with copper ions, the chelating agent is ethylenediaminetetraacetic acid, ammonia diacetic acid, ammonia triacetic acid, N-hydroxyethyl Ethylenediaminetriacetic acid, sodium potassium tartrate, sodium gluconate, triethanolamine, glycerin, tetrahydroxypropylethylenediamine, hydroxy-(1,1)-ethylenediphosphate or aminotrimethylenephosphonic acid; an accelerator The accelerator is a compound having a nitrogen-containing heterocyclic ring, and the accelerator is 1,10-phenanthroline, bipyridine, 2,9-methylene-1,10-phenanthroline, tripyridine or 4- a hydroxypyridine; and a solvent for mixing the copper ion source, the reducing agent, the chelating agent, and the accelerator, The concentration of the copper ion source is 0.01 ~ 0.2M, the concentration of the reducing agent is 0.05 ~ 0.2M, the concentration of the chelating agent and the concentration of 0.05 ~ 0.2M of accelerator is 1 × 10 ^-6 ~ 1 × 10 ^-5 M. The electroless copper plating solution for the silver catalyst copper plating reaction according to the first aspect of the invention, wherein the electroless copper plating solution for the silver catalyst copper plating reaction has a pH of 11 to 13. A silver catalyst copper plating method comprises: providing a working electrode having a silver catalyst on a surface thereof; and placing the working electrode in an electroless copper plating solution for a silver catalyst copper plating reaction Electroless plating, wherein the electroless copper plating solution for the silver catalyst copper plating reaction comprises a copper ion source, a reducing agent, a chelating agent and an accelerator, and the accelerator is a compound having a nitrogen-containing hetero ring. Wherein, the copper ion source is copper sulfate, copper nitrate, copper chloride, copper carbonate, copper tartrate, copper hydroxide or copper acetate, and the reducing agent is formaldehyde, polyoxymethylene, sodium hypophosphite, sodium borohydride, hydroboration Potassium, dimethylamine borane or glucose, the chelating agent is ethylenediaminetetraacetic acid, ammonia diacetic acid, ammonia triacetic acid, N-hydroxyethyl ethylenediamine triacetic acid, sodium potassium tartrate, sodium gluconate, triethanolamine , glycerol, tetrahydroxypropyl ethylene diamine, hydroxy-(1,1)-ethylene diphosphate or aminotrimethylene phosphate, the accelerator is 1,10-phenanthroline, bipyridine, 2,9- Methylene-1,10-phenanthroline, tripyridine or 4-hydroxypyridine, the concentration of the copper ion source is 0.01~ 0.2M, the concentration of the reducing agent is 0.05 to 0.2 M, the concentration of the chelating agent is 0.05 to 0.2 M, and the concentration of the accelerator is 1 × 10 ^-6 to 1 × 10 ^-5 M.